JP2008141851A - Self-starting permanent magnet synchronous motor - Google Patents

Abstract

【Task】
The magnet which adhere | attaches a magnet material with an epoxy resin has the subject that the ratio of the epoxy resin material with respect to a magnet material increases, the ratio of the magnet material which makes a magnet fall, and a magnetic characteristic worsens. Therefore, an object is to provide a self-starting permanent magnet synchronous motor having good characteristics using a permanent magnet having good characteristics.
[Solution]
In the self-starting permanent magnet synchronous motor having a permanent magnet and a bar on a rotor, the permanent magnet is composed of a magnetic powder and a binder having SiO ₂ that binds the magnetic powder. And
[Selection] Figure 1

Description

  The present invention relates to a technology of a self-starting permanent magnet synchronous motor.

  In recent years, the properties of permanent magnets have improved significantly. A typical high-performance permanent magnet is a sintered magnet manufactured by sintering a rare earth magnet material. Although this sintered magnet has excellent magnetic properties, it requires a manufacturing process for sintering at a high temperature, which is a factor of deterioration in productivity.

  In addition, so-called bonded magnets that harden magnet materials with resin have been studied. This magnet is a magnet in which a thermosetting epoxy resin and a magnet material are mixed, and the mixture is molded and manufactured. The magnet material is bonded with an epoxy resin.

  Magnets using an epoxy resin are disclosed in the following Patent Documents 1 to 3. In these Patent Documents, techniques relating to improvement of magnetic characteristics and the like are disclosed.

Japanese Patent Laid-Open No. 11-238640 Japanese Patent Laid-Open No. 11-067514 Japanese Patent Laid-Open No. 10-208919

  In a magnet using a conventional epoxy resin as a binder, a magnet is manufactured by compression molding a mixture of a magnet material and an epoxy resin. The magnet which adheres a magnet material with an epoxy resin has a problem that the ratio of the epoxy resin material to the magnet material is increased, the ratio of the magnet material used for the magnet is decreased, and the magnetic properties are deteriorated. For this reason, the self-starting permanent magnet synchronous motor using the magnet has a problem that the characteristics of the self-starting permanent magnet synchronous motor are remarkably deteriorated.

  An object of the present invention is to provide a self-starting permanent magnet synchronous motor having good characteristics using a permanent magnet having good characteristics.

A feature of the present invention is that in a self-starting permanent magnet synchronous motor, a stator having a stator core and a stator winding, and a rotor rotatably disposed via a gap between the stator and the stator The rotor includes a rotor core, a number of slots provided in the circumferential direction in the vicinity of the outer periphery of the rotor core, a conductive bar embedded in the slots, and the bars in the axial direction. A conductive end ring that is short-circuited at the end face, and a plurality of permanent magnets embedded in a magnet insertion hole arranged on the inner peripheral side of the bar, the permanent magnets constitute field poles, the permanent magnets The magnetic powder is composed of a magnetic powder and a binder having SiO ₂ for binding the magnetic powder.

  A self-starting permanent magnet synchronous motor with good characteristics using a permanent magnet with good characteristics can be provided.

  In the embodiment described below, a permanent magnet provided in a self-starting permanent magnet synchronous motor is manufactured as follows. First, the magnetic material is compression-molded, and the compression-molded magnetic material is impregnated with this material and a binder precursor having excellent wettability to obtain a magnet in which the magnetic material is bound with the binder. By using such a magnet in a self-starting permanent magnet synchronous motor, higher performance self-starting permanent magnet synchronization than a self-starting permanent magnet synchronous motor that uses a magnet using epoxy resin as a binder. An electric motor can be obtained.

  In addition, in the manufacture of the permanent magnet, in addition to the step of binding the magnetic material with a binder, a step of further magnetizing is necessary. This magnetizing step may be performed after a magnet material formed by binding a magnetic material with a binder (described as a magnet) is incorporated into a self-starting permanent magnet synchronous motor component. Rather, it is often easy to manufacture a self-starting permanent magnet synchronous motor by fixing it to a component such as a rotor of a self-starting permanent magnet synchronous motor in a non-magnetized state and then magnetizing it. The magnet functions as a permanent magnet by being magnetized in the magnetizing step.

  In the following examples, there are further excellent effects as follows.

  In the rare earth sintered magnet, it is necessary to heat the rare earth magnet material to a high temperature in order to sinter, and the production cost including the equipment cost becomes high.

  Moreover, the shape and dimension after a sintering process will change with respect to the shape and dimension before a sintering process by the sintering process which heats a magnet material to high temperature. Therefore, in the molding process after the sintering process, a molding operation including significant cutting is required to obtain dimensional accuracy. In the method of the embodiment of the present invention described below, since the magnet can be manufactured at a relatively low temperature, the magnet material can be bound while maintaining the shape and dimensions of the magnet material by press molding with high accuracy. it can. As a result, it becomes easy to produce magnets with high accuracy. For this reason, the magnet after being hardened by the binder is much easier to form than the sintered magnet, and may be unnecessary in some cases.

  In many cases, it is difficult to form a magnet into a curved shape by cutting. Simple curves such as circles can still be cut, but complex curves are often difficult to cut. For curve processing, press working is more suitable than cutting. A sintered magnet needs to be heated to a high temperature for sintering as described above, and requires a large amount of cutting after the sintering process.

  In the embodiment of the present invention described below, since it is not heated to a high temperature after pressing, the shape and dimensional relationship of the pressing are maintained with high accuracy even after the magnet material binding step. For this reason, the final shape of the magnet is often obtained by a slight cutting process, and in some cases, the magnet can be completed without a cutting operation.

  According to the present invention, it is possible to easily produce a curved magnet that has been difficult to manufacture. This makes it possible to manufacture a self-starting permanent magnet synchronous motor with better characteristics.

In the embodiment described below, the magnet material processed after pressing the magnet material is attached to the motor part, for example, inserted into the magnet insertion hole of the rotor, and then the binding work for infiltrating the binder is performed. Is possible. According to this method, it is possible to combine not only the magnet material but also the magnet material and the self-starting permanent magnet synchronous motor component in the vicinity of the magnet in the magnet material binding step. For example, the inner surface of the magnet insertion hole and the inserted magnet can be bonded simultaneously. This improves workability. Further, the durability of the magnet or the parts of the self-starting permanent magnet synchronous motor including the magnet is improved. For this reason, the durability of the self-starting permanent magnet synchronous motor is improved.
<Description of self-starting permanent magnet synchronous motor>
FIG. 1 is a radial sectional view showing an embodiment of a permanent magnet type synchronous motor according to the present invention.

  In FIG. 1, a self-starting permanent magnet synchronous motor 24 includes a stator 8 and a rotor 1.

  The stator 8 includes a stator core 9, a large number (24 in the drawing) of slots 10, and teeth 11 divided by these slots 10. An armature winding 12 composed of a U-phase winding 12A, a V-phase winding 12B, and a W-phase winding 12C is wound with distributed windings in which the same phase is distributed in a number of slots 10.

  In such a configuration, if an AC voltage having a constant frequency is supplied to the armature winding 12, the rotor 1 can be activated and accelerated as an induction motor, and thereafter can be operated at a constant speed as a synchronous motor.

  FIG. 2 is a radial sectional view of a rotor of a synchronous motor according to an embodiment of the present invention.

  In FIG. 2, the rotor 1 is a permanent magnet mainly composed of a rare earth embedded in a large number of squirrel cage windings 3 and magnet insertion holes 7 in a rotor core 2 provided on a shaft 6. 4 are arranged so that the number of magnetic poles is two. In addition, air holes 5 are provided between the magnetic poles so as to prevent leakage magnetic flux generated between the magnetic poles.

  The width opening θ of the permanent magnet 4 is set such that 0.54 <θ / α <0.91 or less with respect to the magnetic pole pitch angle α.

  Although the width opening of the permanent magnet 4 and the circumferential pitch angle of the magnetic flux distribution of the permanent magnet 4 may be different depending on the magnetization, in this embodiment, the circumference of the magnetic flux distribution of the permanent magnet 4 is considered. The direction pitch angle is assumed to be equal to the width opening of the permanent magnet 4.

  FIG. 3 is a graph showing measured data of induced electromotive force waveform distortion and motor efficiency. The horizontal axis represents the ratio θ / α of the magnetic flux pitch angle θ and the magnetic pole pitch angle α, and the vertical axis represents the induced electromotive force waveform. The distortion rate (%) and motor efficiency (%) are shown.

According to Japanese Industrial Standard JIS-C4212, the efficiency of a high-efficiency low-pressure three-phase squirrel-cage induction motor is, for example, fully closed, with an output of 3.7 kW, 2-pole, 200 V, and 50 Hz operating at a refrigerant temperature of 40 ° C. or less. It is necessary to satisfy 87.0% or more. From this, the efficiency of the permanent magnet type synchronous motor is driven in a compressor that becomes an environment having a refrigerant temperature of 100 ° C. or higher.
If it is 87% or more, it can be said that it is a favorable characteristic compared with the induction motor of a comparable physique.

  In FIG. 3, when the ratio θ / α between the width opening θ and the magnetic pole pitch α is 0.62 or more and 0.91 or less, an efficiency of 87% or more can be secured, but the ratio of θ / α is It has a peak in a range exceeding 0.67, and it was found that the most excellent characteristics were obtained when the ratio θ / α was 0.72. Therefore, it can be said that it is desirable to set the ratio of θ / α as 0.67 or more and 0.91 or less as motor characteristics.

  The reason for this is that if the circumferential pitch angle θ of the permanent magnet is excessively increased, the magnetic flux of the permanent magnet increases and the iron loss generated in the stator increases. Further, the induced electromotive force increases with respect to the applied voltage, and field weakening driving is performed, so that the input current increases. On the other hand, if the circumferential pitch angle θ of the permanent magnet is extremely small, the amount of magnetic flux of the permanent magnet is reduced, and the induced electromotive force is minimized with respect to the applied voltage, resulting in a magnetizing action, which also increases the input current. is there.

On the other hand, paying attention to the distortion factor of the induced electromotive force waveform in the graph, it can be seen that the θ / α ratio can be minimized when the ratio is 0.54 to 0.67. Although it is not an effective dimension from the viewpoint of motor efficiency, it is considered to have a sufficiently valuable aspect from the viewpoint of motor vibration and noise. Based on this result, the circumferential pitch angle θ of the permanent magnet 4 or the circumferential pitch angle θ of the magnetic flux distribution created by the permanent magnet 4 is configured to be 0.54 to 0.91 of the magnetic pole pitch angle α.
<Description of the permanent magnet 4>
Here, the permanent magnet 4 has a structure in which a neodymium (Nd) powder of a rare earth material, which is a magnet material, is bound with a binder having a property that the neodymium (Nd) and the precursor have good affinity. Here, the precursor having excellent affinity is, for example, alkoxysiloxane or alkoxysilane which is a precursor of SiO ₂ .

The neodymium (Nd) powder has a plate-like shape, and the thickness in the X-axis and Y-axis directions is several times larger than the value in the Z-axis direction, which is the height direction. I am doing. The size of neodymium (Nd) powder in the X-axis or Y-axis direction should be large. For example, it is better to use powder whose size in the X-axis or Y-axis direction is 45 μm or more. Residual properties are improved. Neodymium (Nd) powder breaks down during molding, and it is inevitable that small-sized powder is mixed, but it is desirable that more than half of the powder is a powder having a size of 45 μm or more, Furthermore, more preferable results can be obtained when 70% or more is a powder having a size of 45 μm or more. Even more preferable results can be obtained when 90% or more is a powder having a size of 45 μm or more. If neodymium (Nd) further contains dysprosium (Dy), the characteristics are improved. By including this dysprosium (Dy), good magnetic characteristics are maintained even if the temperature of the self-starting permanent magnet synchronous motor rises. The content of dysprosium (Dy) is about several percent, and at most 10%. A magnet having a structure in which a rare earth magnet material powder is bound with a binder will be described in detail later.
<Manufacturing method of permanent magnet 4>
An example of the manufacturing process of the permanent magnet 4 according to the present embodiment is shown in FIG. In step 10, a powdered magnet material is generated. For example, rare earth magnet magnetic powders can be produced by quenching a mother alloy with an adjusted composition.

  In the present embodiment, non-oxide magnetic powder is used, and in particular, rare earth magnet, for example, magnetic powder such as NdFeB is used. In the present invention, a permanent magnet can be manufactured in a relatively low temperature step by using the method described in detail below. Thereby, even if it is a case where a non-oxide magnetic powder is used, the oxidation of a magnetic powder can be suppressed and a magnet with a high magnetic characteristic can be obtained.

  In step 15, the powdery magnet material is compression molded. For example, when manufacturing a permanent magnet for use in a self-starting permanent magnet synchronous motor, in this step 15, the final magnet shape mold of the permanent magnet used in the self-starting permanent magnet synchronous motor is used, and the mold is powdery. The magnet material is supplied and compression molded. The compression-molded magnet material is in a porous state whose shape is determined by a mold, has a low mechanical strength, and is broken when subjected to a strong impact. Moreover, since it is not magnetized, it does not have the characteristics as a permanent magnet. Even if magnetized in this compression-molded state, it is difficult to use as a component of a self-starting permanent magnet synchronous motor in terms of mechanical strength.

  The compression-molded magnet uses the manufacturing method described in detail below, so that the dimensional relationship of the magnet shape does not change much in the subsequent steps. That is, the shape compression-molded in step 15 can be maintained with high accuracy. For example, when the following manufacturing process is used, it may be necessary to cut and mold a part such as a burr of the binder that binds the magnet material, but many parts of the shape maintain high accuracy and self-start There is a high possibility that the required magnet accuracy can be achieved in the permanent magnet synchronous motor.

  In sintered magnets, it is necessary to heat the compression-molded magnet material to a high temperature in the manufacturing process, and there is a problem that the shape of the magnet is deformed from the shape of the compression-molding by cooling after heating to a high temperature. . For this reason, in the conventional sintered magnet, in order to maintain the precision of a final shape, cutting was essential. As a result, there is a problem that productivity is deteriorated. In addition, it is difficult to process a curved shape by cutting, and a magnet having a curved shape cannot be easily produced.

In step 20, the compression-molded magnet molded body is impregnated with a SiO ₂ precursor solution. The compression-molded magnet compact is in a porous state, impregnated with a binder precursor having a low viscosity and good wettability with respect to the magnet material. Since the precursor has good wettability and low viscosity with respect to the compression-molded magnet molded body, it is impregnated so that the precursor is sucked into the porous compression molded body. Specific precursors are described in detail below.

  By impregnating a precursor solution of a binder having good wettability with respect to the magnet compact, the surface of each magnetic powder constituting the magnet compact is covered with the binder, resulting in a large number of powders. It works to join together. Further, since the precursor solution of the binder enters into the details of the magnet molded body due to the action of good wettability, a good binding effect can be obtained with a small amount of binder. In addition, the use of good wettability makes the equipment relatively simple and inexpensive compared to the use of epoxy resin. Further, since the precursor described in detail below is cured at a relatively low temperature, the step 20 can be performed in a temperature range of 120 degrees to 200 degrees, particularly about 150 degrees. Thereby, the final magnet can be obtained while maintaining the size and shape of the compression molded body with high accuracy. Moreover, it can suppress that the magnetic powder for magnets, such as NdFeB, oxidizes, and can prevent the fall of a magnetic characteristic. Of course, burr of the binder can be made in the step of impregnating the precursor, but since the size and shape of the compacted compact of the powder magnet do not change, the magnet is manufactured by cutting the binder. The

Step 25 is a step of binding the magnet material with the binder by heat-treating the impregnated compression molded body. As described in detail below, a good magnet can be obtained by binding a magnet material using SiO ₂ as a binder. As will be described in detail below, the processing temperature in step 25 is a relatively low temperature, and the shape and dimensions of the magnet compact are hardly changed by this heat treatment, and the relationship between the shape and dimensions of the manufactured magnets. High accuracy is maintained for the compression-molded shape and dimensions.
<Binder of permanent magnet 4>
The binder precursor solution used in the step 20 has an alkoxysiloxane and an alkoxysilane, which are SiO ₂ precursors, and has terminal groups and side chains as shown in Chemical Formula 2 and Chemical Formula 3. It has a compound having an alkoxy group.

  Further, the alcohol of the solvent is preferably a compound having the same skeleton as the alkoxy group in alkoxysiloxane or alkoxysilane, but is not limited thereto. Specific examples include methanol, ethanol, propanol, isopropanol and the like. The catalyst for hydrolysis and dehydration condensation may be any of an acid catalyst, a base catalyst, and a neutral catalyst, but the neutral catalyst is most preferable because corrosion of the metal can be minimized. As the neutral catalyst, an organotin catalyst is effective. Specifically, bis (2-ethylhexanoate) tin, n-butyltris (2-ethylhexanoate) tin, di-n-butylbis (2-ethyl) Hexanoate) tin, di-n-butylbis (2,4-pentanedionate) tin, di-n-butyl dilauryl tin, dimethyl dineodecanoate tin, dioctyl dilarylate tin, dioctyl dineodecano Examples include, but are not limited to, ate tin. Examples of the acid catalyst include dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, formic acid, acetic acid, and the like, and examples of the base catalyst include sodium hydroxide, potassium hydroxide, aqueous ammonia, and the like, but are not limited thereto.

The total content of alkoxysiloxane, alkoxysilane, hydrolysis product thereof, and dehydration condensate thereof, which is a precursor of SiO _{2 in} the binder solution, is preferably 5 vol% or more and 96 vol% or less. When the total content of alkoxysiloxane, alkoxysilane, its hydrolysis product, and its dehydration condensate is less than 5 vol%, the binder content in the magnet is low. The strength of is slightly reduced. On the other hand, alkoxysiloxane, alkoxysilane, hydrolysis product thereof, and when the content of dehydrated condensates total is more than 96 vol%, alkoxysiloxane that is a precursor of SiO _2, the fast reaction of the molecular weight of the alkoxysilane Therefore, the thickening speed of the binder solution is also increased. This means that it is more difficult to control the proper viscosity of the binder solution, and it becomes more difficult to use this binder solution for the impregnation method than the materials described above.

Hydroxylation shown in the following chemical formula 4 and chemical formula 5 occurs with the alkoxysiloxane or alkoxysilane which is the precursor of SiO _{2 in} the binder solution and water. Here, the chemical reaction formula is a reaction formula when hydrolysis partially occurs.

At this time, the amount of water added is one of the factors governing the progress of the hydrolysis reaction of alkoxysiloxane or alkoxysilane. This hydrolysis reaction is important for increasing the mechanical strength of the binder after curing. This is because if the hydrolysis reaction of alkoxysiloxane or alkoxysilane does not occur, the dehydration condensation reaction between the alkoxysiloxane or alkoxysilane hydrolysis reaction products that occurs next does not proceed. This is because the dehydration condensation reaction product is SiO ₂ , and this SiO ₂ has high adhesiveness with magnetic powder and becomes an important material for increasing the mechanical strength of the binder. Furthermore, the OH group of silanol has a strong interaction with the O atom or OH group on the surface of the magnetic powder and contributes to high adhesion. However, when the hydrolysis reaction proceeds and the concentration of silanol groups increases, dehydration condensation reaction between organosilicon compounds containing silanol groups (alkoxysiloxane or alkoxysilane hydrolysis products) proceeds, and the molecular weight of the organosilicon compounds increases. The viscosity of the binder solution increases. This is a characteristic that an appropriate state of the binder solution used in the impregnation method is not suitable. Accordingly, it is necessary to add an appropriate amount of water to the alkoxysiloxane or alkoxysilane that is the precursor of SiO _{2 in} the binder solution. Here, the addition amount of water in the insulating layer forming treatment liquid is preferably 1/10 to 1 of the reaction equivalent in the hydrolysis reaction shown in the chemical reaction formulas 1 and 2. When the amount of water added is 1/10 or less of the reaction equivalent in the hydrolysis reaction shown in Chemical Reaction Formulas 1 and 2, since the concentration of silanol groups in the organosilicon compound is low, the organosilicon compound containing silanol groups and the magnetic powder surface low interaction, but also because the alkoxy group in the product for dehydration condensation reaction is hard to occur to produce SiO ₂ is that a large amount of remaining defect is generated number in SiO _2, the strength of the SiO ₂ is low Become. On the other hand, if the amount of water added is greater than 1 of the reaction equivalent in the hydrolysis reaction shown in Chemical Reaction Formulas 1 and 2, the organosilicon compound containing silanol groups is likely to undergo dehydration condensation and the binder solution increases. Since it is viscous, the binder solution cannot penetrate into the gap between the magnetic powder and the magnetic powder, and the binder solution used in the impregnation method has a characteristic of moving away from an appropriate state. Alcohol is usually used as the solvent in the binder solution. This is because the alkoxy group in the alkoxysiloxane has a fast dissociation reaction in the solvent used for the binder solution, and is in equilibrium with the solvent alcohol. Therefore, methanol, ethanol, n-propanol, and iso-propanol having a boiling point lower than that of water and low viscosity are preferable as the solvent alcohol. However, although the stability of the solution is slightly decreased chemically, the viscosity of the binder solution does not increase in a few hours and the solvent of the present invention has a lower boiling point than water. Any water-soluble solvent such as ketones such as acetone can be used.

  The following matters can be confirmed about the one aspect | mode of the binder of this invention demonstrated above.

First, the precursor of SiO ₂ is not a solution using an aqueous solution as a solvent, but a solution using an alcohol as a solvent. Water is only added to adjust the hydrolysis reaction. By impregnating with an alcohol-based solution instead of an aqueous solution, almost no water remains after thermosetting. Since the remaining water in the permanent magnet is suppressed, the magnetic characteristics are not deteriorated over time due to oxidation or the like. On the other hand, since hydrolysis is performed using alkoxysiloxane, alkoxysilane or the like as a precursor of SiO ₂ , methoxy may remain. Therefore, it is conceivable that the manufactured permanent magnet contains magnetic powder and methoxy in addition to the binder for binding the magnetic powder.

Next, the magnet produced | generated by the said process becomes a structure which bound the rare earth magnet magnetic powders, such as NdFeB, with the SiO-type binder. This binder takes an amorphous (non-crystalline) continuous film structure. As described above, the binder is basically composed of SiO ₂ , but since it is amorphous, a composition such as SiO may partially exist. If a continuous film mainly composed of Si and O, that is, a binder composed of a SiO-based continuous film is formed, it is considered that the magnet according to the present embodiment is configured.

Next, a configuration using an oxide glass material other than SiO-based as a binder will be examined. As described above, various requirements are imposed on the precursor as the impregnation solution in order to perform the manufacturing process of the present invention. It has a low viscosity, high permeability, high stability, and curing at a relatively low temperature. It has been confirmed that the SiO-based binder is the best for satisfying these requirements, but other oxide glassy materials can be used as binders if the requirements suitable for this production process are satisfied. However, a certain degree of effect can be expected.
<Other Embodiments of Manufacturing Method of Permanent Magnet 4>
Another embodiment of the magnet manufacturing process according to the present invention is shown in FIGS. The embodiment of FIG. 5 is different from the process of FIG. 4 described above in that a step of applying an insulating film to the powdered magnet material after generation and before compression molding is added. Further, FIG. 6 is different in that the compression-molded magnet is attached to the rotor, and thereafter the treatment of impregnating the binder is performed.

  In FIG. 5, the same process numbers as those in FIG. 4 indicate substantially the same processing contents. In step 10, a powdered magnet material is generated, and an electrical insulating film is formed on the surface of each powder of the magnet material generated in step 12. It is desirable to make an electrical insulating layer as uniform as possible on the entire surface of the magnetic powder as much as possible, and a specific treatment method will be described later. When the manufactured magnet is used in a self-starting permanent magnet synchronous motor, it is used in an alternating magnetic field as described above. The magnetic flux passing through the magnet changes periodically, and an eddy current is generated in the magnet due to the change of the magnetic flux. This eddy current has a problem of reducing the efficiency of the self-starting permanent magnet synchronous motor, and there is a risk that the eddy current may increase heat generation in the magnet. By covering the surface of each magnetic material powder with an insulating layer, this eddy current can be suppressed and reduction in efficiency of the rotating machine can be suppressed, and the heat generated by the magnet can be generated by the self-starting permanent magnet synchronous motor. Can be suppressed. In particular, in the magnet built in the rotor, the rotor is mechanically connected to the housing of the self-starting permanent magnet synchronous motor through a bearing, and the heat conductivity is not good. For this reason, it is important to suppress the heat generation of the magnet.

When magnets are used under the condition that AC magnetic flux including harmonics is applied to the magnets, rare earth magnet materials have a low electrical resistance, and on the surface of rare earth magnet powders from the viewpoint of suppressing eddy currents and suppressing heat generation. An inorganic insulating film is preferably formed. In order to form an inorganic insulating film on the surface of the rare earth magnet powder, a phosphate chemical conversion film is preferably applied as the inorganic insulating film. When phosphoric acid, magnesium, or boric acid is used for the phosphating solution, the following composition is good. Phosphorus acid content is desirably 1~163g / dm ^3, cause a decrease in 163 g / dm ³ larger than the magnetic flux density, smaller and insulating 1 g / dm ³ is deteriorated. The amount of boric acid is preferably 0.05 to 0.4 g per 1 g of phosphoric acid, and if it exceeds this range, the stability of the insulating layer is deteriorated. In order to form the insulating layer as uniformly as possible on the entire surface of the magnetic powder, it is effective to improve the wettability of the insulating layer forming treatment liquid to the magnetic powder. For this, addition of a surfactant is desirable. Examples of such surfactants include perfluoroalkyl-based, alkylbenzenesulfonic acid-based, zwitterionic-based, or polyether-based surfactants, and the amount added is 0.01 in the insulating layer forming treatment liquid. If it is less than 0.01% by weight, the effect of lowering the surface tension and wetting the surface of the magnetic powder is insufficient, and if it exceeds 1% by weight, no further effect can be expected and it is uneconomical. It is.

Further, it is desirable to add a rust preventive agent from the viewpoint of preventing deterioration of the characteristics of the magnet. The amount of rust inhibitor is desirably 0.01~0.5mol / dm ^3, 0.01mol / dm difficult suppression of rust surface of the magnetic powder is less than ^3, 0.5 mol / dm more than ³ more than the effect Is not economical because it cannot be expected.

  The addition amount of the phosphating solution depends on the average particle size of the rare earth magnet magnetic powder. When the average particle size of the rare earth magnet magnetic powder is 0.1 to 500 μm, 300 to 25 ml is desirable for 1 kg of the rare earth magnet magnetic powder. If the amount exceeds 300 ml, the insulating film on the surface of the magnetic powder becomes too thick, and rust is likely to occur, leading to a decrease in magnetic flux density at the time of magnet production. As a result, the amount of rust generated increases, which may cause deterioration of the magnet characteristics.

  The rare earth fluoride or alkaline earth metal fluoride in the coating film forming treatment liquid swells in a solvent mainly composed of alcohol. The rare earth fluoride or alkaline earth metal fluoride gel has a gelatinous flexible structure. This is because alcohol has excellent wettability with respect to rare earth magnet magnetic powder. Also, the average particle size of the rare earth fluoride or alkaline earth metal fluoride in the gel state must be pulverized to a level of 10 μm or less because the coating film formed on the surface of the rare earth magnet magnetic powder has a uniform thickness. It is easy. Furthermore, by using a solvent containing alcohol as a main component, it is possible to suppress the oxidation of rare earth magnet magnetic powder that is very easily oxidized.

Furthermore, a fluoride coat film is desirable as the inorganic insulating film for the purpose of improving the insulating properties and magnetic characteristics of the magnetic powder. For this reason, when a fluoride coating film is formed on the surface of rare earth magnet powder, the concentration of rare earth fluoride or alkaline earth metal fluoride in the fluoride coating film forming solution is formed on the surface of the magnetic powder for rare earth magnets. Depending on the film thickness, the rare earth fluoride or alkaline earth metal fluoride is swollen in a solvent mainly composed of alcohol, and the average particle diameter of the rare earth fluoride or alkaline earth metal fluoride in a gel state Is preferably pulverized to a level of 10 μm or less and dispersed in a solvent containing alcohol as a main component. The concentration of rare earth fluoride or alkaline earth metal fluoride is 200 g / dm ³ to 1 g / dm. ³

  The addition amount of the rare earth fluoride coating film forming treatment liquid depends on the average particle diameter of the rare earth magnet magnetic powder. When the average particle diameter of the rare earth magnet magnetic powder is 0.1 to 500 μm, 300 to 10 ml is desirable for 1 kg of the rare earth magnet magnetic powder. This is because if the amount of the treatment liquid is large, not only it takes time to remove the solvent, but also the magnetic powder for rare earth magnets is easily corroded. On the other hand, when the amount of the processing liquid is small, a portion where the processing liquid does not get wet occurs on the surface of the rare earth magnet magnetic powder. Regarding the above matters, Table 1 summarizes the effective concentrations and the like of the treatment liquid for rare earth fluoride and alkaline earth metal fluoride coating films.

  In the process of FIG. 5, an insulating film is formed on the surface of each powder of rare earth magnet material in step 12, and then the magnet material is compression molded in step 15 to form a porous magnet. Thereafter, the precursor of the binder is impregnated in step 20 as in FIG. 4, and the precursor is cured in step 25 to bind the magnet material with the binder.

The example of the magnet manufacturing process according to the present invention has been described above with reference to FIGS. 4 and 5. FIG. 6 shows a method in which a porous magnet compression-molded before the binder impregnation step is inserted into the magnet insertion hole of the rotor, and then the binder precursor is poured into the magnet insertion hole and impregnated. The processes up to step 15 are the same as those already described. In step 17, a porous compressed magnet is inserted into the magnet insertion hole provided in the rotor core, and the SiO ₂ precursor solution is poured into the rotor magnet insertion hole in step magnet 22.
Next, when the temperature of the rotor itself is raised in step 27, the precursor is cured, the strength of the compression-molded magnet is increased, and the magnet is fixed in the magnet insertion hole of the rotor core.

In this example, magnetic powder obtained by pulverizing a NdFeB-based ribbon produced by rapidly cooling a mother alloy having an adjusted composition was used as the rare earth magnet magnetic powder. NdFeB master alloy is iron,
Nd is mixed with an Fe-B alloy (ferroboron) and dissolved in a vacuum, an inert gas, or a reducing gas atmosphere to make the composition uniform. If necessary, the master alloy cut by a single roll or twin roll method is used, and the master alloy dissolved on the surface of the rotating roll is injected and quenched in an inert or reducing gas atmosphere such as argon gas. After forming the ribbon, heat treatment is performed in an inert gas or a reducing gas atmosphere. The heat treatment temperature is 200 ° C. or more and 700 ° C. or less, and Nd ₂ Fe ₁₄ B microcrystals grow by this heat treatment. The ribbon has a thickness of 10 to 100 μm, and the crystallite size of Nd ₂ Fe ₁₄ B is 10 to 100 nm.

When the Nd ₂ Fe ₁₄ B microcrystals have an average size of 30 nm, the grain boundary layer has a composition close to that of Nd ₇₀ Fe ₃₀ and is thinner than the single-domain critical grain size, so that the inside of the Nd ₂ Fe ₁₄ B microcrystals It is difficult to form a domain wall. The magnetizations of Nd ₂ Fe ₁₄ B microcrystals are magnetically coupled in the respective microcrystals, and it is presumed that the magnetization reversal is caused by propagation of the domain wall. One technique for suppressing magnetization reversal is to facilitate magnetic coupling between magnetic powders obtained by pulverizing a ribbon. For this purpose, it is effective to make the nonmagnetic part between magnetic powders as thin as possible. The pulverized powder is inserted into a WC carbide mold to which Co is added and then compression molded with a top and bottom punch at a press pressure of 5t-20t / cm ^2. There are few nonmagnetic parts between magnetic particles in the direction perpendicular to the pressing direction. Since the magnetic powder is a flat powder obtained by pulverizing a ribbon, anisotropy occurs in the arrangement of the flat powder in a compression molded product, and the long axis of the flat powder (thickness of the ribbon) is perpendicular to the pressing direction. (Parallel to the direction perpendicular to the direction). As a result of the long axis direction of the flat powder being easily oriented in the direction perpendicular to the press direction, the magnetization direction is reversed in the vertical direction of the formed body because the magnetization is continuous in the vertical direction and the permeance is greater in each powder. It becomes difficult to do. For this reason, a difference occurs in the demagnetization curve between the pressing direction of the compact and the direction perpendicular to the pressing direction. When a 10 × 10 × 10 mm compact is magnetized at 20 kOe in the direction perpendicular to the press direction and the demagnetization curve is measured, the residual magnetic flux density (Br) is 0.64 T and the coercive force (iHc) is 12.1 kOe. On the other hand, when magnetized with a magnetic field of 20 kOe in the direction parallel to the press direction, the demagnetization curve was measured in the magnetization direction to be Br 0.60 T and iHc 11.8 kOe. This difference in demagnetization curve is considered to be caused by the fact that flat powder is used for the magnetic powder used in the molded body, and the orientation of the flat powder has anisotropy in the molded body. It is done.

This difference in demagnetization curve is considered to be caused by the fact that flat powder is used for the magnetic powder used in the molded body, and the orientation of the flat powder has anisotropy in the molded body. It is done. The crystal grains of each flat powder are as small as 10-100 nm and the crystal orientation is small, but the shape of the flat powder has anisotropy. Is magnetically anisotropic. The test piece of such a molded body was impregnated with the following SiO ₂ precursor solutions 1) to 3) and heat-treated. The implemented process is demonstrated below.

The following three solutions were used for the SiO ₂ precursor as a binder.

1) 5 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, average is 4), 0.96 ml of water, 95 ml of dehydrated methyl alcohol, dibutyltin dilaurate 0 0.05 ml was mixed and left at a temperature of 25 ° C. for 2 days and nights.

2) 25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, average is 4), water 4.8 ml, dehydrated methyl alcohol 75 ml, dibutyltin dilaurate 0 0.05 ml was mixed and left at a temperature of 25 ° C. for 2 days and nights.

_{3) CH 3 O- (Si (} CH 3 O) 2 -O) m -CH 3 (m is 3-5, average 4) 100 ml, water 3.84 ml, dibutyltin dilaurate 0.05ml were mixed It was left at a temperature of 25 ° C. for 4 hours.

The viscosities of the SiO ₂ precursor solutions 1) to 3) were measured at a temperature of 30 ° C. using an Ostwald viscometer.

(1) The above Nd ₂ Fe ₁₄ B magnetic powder is filled into a mold, and a test piece of 10 mm in length, 10 mm in width and 5 mm in thickness is used for measuring magnetic properties at a pressure of 16 t / cm ² , and for measuring strength. A compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared.

(2) The compression molded test piece prepared in (1) is placed in the bat so that the pressing direction is horizontal, and the SiO ₂ precursor solution of 1) to 3) as the binder is placed in the bat. Injection was performed so that the liquid level was 1 mm / min in the vertical direction. The SiO ₂ precursor solution was poured into the vat until it was finally 5 mm above the upper surface of the compression molded specimen.

(3) The compression-molded test piece used in (2) was placed, and the bat filled with the SiO ₂ precursor solution was set in a vacuum vessel and gradually exhausted to about 80 Pa. The sample was left until the generation of bubbles from the surface of the compression molded test piece was reduced.

(4) The compression molded test piece was placed, the internal pressure of the vacuum vessel in which the bat filled with the SiO ₂ precursor solution was set was gradually returned to atmospheric pressure, and the compression molded test piece was taken out from the SiO ₂ precursor solution. .

(5) The compression molding test piece impregnated with the SiO ₂ precursor solution prepared in (4) is set in a vacuum drying furnace, and vacuum is applied to the compression molding test piece under the conditions of 1 to 3 Pa and 150 ° C. Heat treatment was applied.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece of 10 mm length, 10 mm width, and 5 mm thickness produced in (5).

  (7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was carried out using the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (5). For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

FIG. 7 shows an example of SEM observation results of the cross-section of a compression molded test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm produced in (5). 7A is a secondary electron image, FIG. 7B is an oxygen surface analysis image, and FIG. 7C is a silicon surface analysis image. As shown to (a), the flat powder has accumulated with anisotropy and the crack has generate | occur | produced partially. Further, oxygen and silicon are detected along the surface of the flat powder and the cracks inside the flat powder. This crack is generated at the time of compression molding and is a cavity before the impregnation treatment. From this, it was found that the SiO ₂ precursor solution was impregnated into the cracks in the magnetic powder.

Regarding the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (5), the residual magnetic flux density can be improved by 20-30% compared to the resin-containing bond magnet (Comparative Example 1). , and the demagnetization curve was measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. Further, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere is 3.0% for the SiO ₂ impregnated bonded magnet, which is smaller than the thermal demagnetization factor (5%) without SiO ₂ impregnation. Further, the irreversible thermal demagnetization rate after returning to room temperature after 1 hour at 200 ° C. and re-magnetization is less than 1% when the impregnation treatment is performed, whereas the value is close to 3% in the case of the epoxy bond magnet (Comparative Example 1). Met. This is because the surface of the powder containing cracks is protected by SiO ₂ by the impregnation treatment, thereby preventing corrosion such as oxidation and reducing the irreversible thermal demagnetization rate. That is, since the surface of the powder including cracks is protected by the impregnation treatment with the SiO ₂ precursor, corrosion such as oxidation is suppressed, and the irreversible thermal demagnetization rate is reduced. In addition to suppressing irreversible thermal demagnetization, the impregnated magnet has obtained less demagnetization results in the PCT test and the salt spray test.

  Further, the compression molded test piece having a length of 10 mm, a width of 10 mm and a thickness of 5 mm produced in (5) was kept at 225 ° C. for 1 hour in the atmosphere, and after cooling, the demagnetization curve was measured at 20 ° C. The magnetic field application direction was 10 mm. First, after magnetization with a magnetic field of +20 kOe, a demagnetization curve was measured by alternately applying a magnetic field between ± 1 kOe and ± 10 kOe.

The result is shown in FIG. Here, the demagnetization curves of a magnet impregnated under the above condition 2) and a compression-molded bonded magnet containing 15 vol% of an epoxy resin as a binder, which will be described later, are compared. In FIG. 8, the horizontal axis represents the applied magnetic field, and the vertical axis represents the residual magnetic flux density. In the magnet subjected to the impregnation treatment, when a magnetic field larger than −8 kOe is applied to the negative side, the magnetic flux rapidly decreases. The compression-molded bonded magnet has a magnetic field whose value is smaller than that of the impregnated magnet, and the magnetic flux rapidly decreases. The magnetic field on the negative side of −5 kOe is significantly decreased. The residual magnetic flux density after applying a magnetic field of −10 kOe is 0.44 for the impregnated magnet, and 0.11 T for the compression-molded bonded magnet, and the residual magnetic flux density of the impregnated magnet is four times the value of the compression-molded bonded magnet. ing. This is because the magnetic anisotropy of the NdFeB crystals constituting each NdFeB powder is reduced by oxidizing the surface of each NdFeB powder and the crack surface of the NdFeB powder while the compression molded bonded magnet is heated at 225 ° C. This is considered to be because the coercive force decreased and the magnetization was easily reversed by applying a negative magnetic field. On the other hand, in the impregnated magnet, the NdFeB powder and the crack surface are covered with the SiO ₂ film, so that it is considered that the reduction in coercive force is small as a result of preventing oxidation during heating in the atmosphere.

The bending strength of the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (7) is ₂ MPa or less before the SiO ₂ impregnation, but 30 MPa or more after the SiO ₂ impregnation heat treatment, ₂ in this example. ), 3) When the SiO ₂ precursor solution was used, it was possible to produce a magnet molded body having a bending strength of 100 MPa or more.

  The specific resistance of the magnet was about 10 times that of the sintered rare earth magnet, but about 1/10 that of the compressed rare earth bonded magnet. became. However, when used as a self-starting permanent magnet synchronous motor, the occurrence of eddy current loss is small and there is no problem. In particular, in a self-starting permanent magnet synchronous motor with a built-in magnet, the harmonic magnetic flux does not penetrate deeply into the interior of the rotor cage winding 3, so there is little eddy current in the magnet and this is not a big problem.

From the results of this example, the rare earth bonded magnet impregnated in the rare earth magnet molded body produced by the cold forming method without using the low-viscosity SiO ₂ precursor of the present invention is compared with a normal resin-containing rare earth bonded magnet. Thus, it was found that the magnetic characteristics were improved by 20 to 30%, the bending strength was equivalent to 3 times, the irreversible thermal demagnetization rate was reduced to half or less, and the magnet was highly reliable.

  Table 2 summarizes the magnet characteristics when binders 1) to 3) are used for this example and (Example 2) to (Example 5) described later.

In this example, magnetic powder obtained by pulverizing a NdFeB-based ribbon similar to [Example 1] was used for the rare earth magnet magnetic powder. In addition, the following three solutions were used as precursors for the SiO ₂ binder.

_{1) CH 3 O- (Si (} CH 3 O) 2 -O) m -CH 3 (m is 3-5, average 4) 25 ml, water 0.96 ml, dehydrated methanol 75 ml, dibutyltin dilaurate 0 0.05 ml was mixed and left at a temperature of 25 ° C. for 2 days and nights.

2) 25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, average is 4), water 4.8 ml, dehydrated methyl alcohol 75 ml, dibutyltin dilaurate 0 0.05 ml was mixed and left at a temperature of 25 ° C. for 2 days and nights.

_{3) CH 3 O- (Si (} CH 3 O) 2 -O) m -CH 3 (m is 3-5, average 4) 100 ml, water 9.6 ml, dehydrated methanol 75 ml, dibutyltin dilaurate 0 0.05 ml was mixed and left at a temperature of 25 ° C. for 2 days and nights.

The viscosities of the SiO ₂ precursor solutions 1) to 3) were measured at a temperature of 30 ° C. using an Ostwald viscometer.

(1) The above Nd ₂ Fe ₁₄ B magnetic powder is filled in a mold, and a test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm is used for measuring magnetic properties at a pressure of 16 t / cm ² . A compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared.

(2) The compression molded test piece prepared in (1) is placed in the bat so that the pressing direction is horizontal, and the SiO ₂ precursor solution of 1) to 3) as the binder is placed in the bat. Injection was performed so that the liquid level was 1 mm / min in the vertical direction. The SiO ₂ precursor solution was poured into the vat until it was finally 5 mm above the upper surface of the compression molded specimen.

(3) The compression-molded test piece used in (2) was placed, and the bat filled with the SiO ₂ precursor solution was set in a vacuum vessel and gradually exhausted to about 80 Pa. The sample was left until the generation of bubbles from the surface of the compression molded test piece was reduced.

(4) The compression molded test piece was placed, the internal pressure of the vacuum vessel in which the bat filled with the SiO ₂ precursor solution was set was gradually returned to atmospheric pressure, and the compression molded test piece was taken out from the SiO ₂ precursor solution. .

(5) The compression molding test piece impregnated with the SiO ₂ precursor solution prepared in (4) is set in a vacuum drying furnace, and vacuum is applied to the compression molding test piece under the conditions of 1 to 3 Pa and 150 ° C. Heat treatment was applied.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece of 10 mm length, 10 mm width, and 5 mm thickness produced in (5).

  (7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was carried out using the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (5). For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

Regarding the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (5), the residual magnetic flux density can be improved by 20-30% compared to the resin-containing bond magnet (Comparative Example 1). , and the demagnetization curve was measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. Further, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere is 3.0% for the SiO ₂ impregnated bonded magnet, which is smaller than the thermal demagnetization factor (5%) without SiO ₂ impregnation. Furthermore, the irreversible heat demagnetization rate is also maintained in the atmosphere at 200 ° C. for 1 hour,
It is 1% or less after the SiO ₂ impregnation heat treatment and is smaller than a value close to 3% in the case of no SiO ₂ impregnation. This is because SiO ₂ suppresses deterioration due to oxidation of magnetic powder.

The bending strength of the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (7) is ₂ MPa or less before the SiO ₂ impregnation, but 70 MPa or more after the SiO ₂ impregnation heat treatment. ), 3) When the SiO ₂ precursor solution was used, it was possible to produce a magnet molded body having a bending strength of 100 MPa or more.

  The specific resistance of the magnet was about 10 times that of the sintered rare earth magnet, but about 1/10 that of the compressed rare earth bonded magnet. became. Although eddy current loss may increase slightly, it does not interfere with use.

From the results of this example, the rare earth bonded magnet impregnated in the rare earth magnet molded body produced by the cold forming method without using the low-viscosity SiO ₂ precursor of the present invention is compared with a normal resin-containing rare earth bonded magnet. As a result, it was found that the magnetic properties are 20-30%, the bending strength is 2-3 times, the irreversible thermal demagnetization rate is reduced to less than half, and the magnet can be highly reliable.

In this example, magnetic powder obtained by pulverizing a NdFeB-based ribbon similar to [Example 1] was used for the rare earth magnet magnetic powder. The following three solutions were used for the SiO ₂ precursor as a binder.

1) Mix CH ₃ O— (Si (CH ₃ O) ₂ —O) —CH ₃ with 25 ml, 5.9 ml of water, 75 ml of dehydrated methyl alcohol, and 0.05 ml of dibutyltin dilaurate. Left alone.

2) 25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, average is 4), 4.8 ml of water, 75 ml of dehydrated methyl alcohol, dibutyltin dilaurate 0 0.05 ml was mixed and left at a temperature of 25 ° C. for 2 days and nights.

_{3) CH 3 O- (Si (} CH 3 O) 2 -O) m -CH 3 (m is 6-8, average 7) a 25 ml, water 4.6 ml, dehydrated methanol 75 ml, dibutyltin dilaurate 0 0.05 ml was mixed and left at a temperature of 25 ° C. for 2 days and nights.

The viscosities of the SiO ₂ precursor solutions 1) to 3) were measured at a temperature of 30 ° C. using an Ostwald viscometer.

(1) The above Nd ₂ Fe ₁₄ B magnetic powder is filled in a mold, and a test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm is used for measuring magnetic properties at a pressure of 16 t / cm ² . A compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared.

(2) The compression molded test piece prepared in (1) is placed in the bat so that the pressing direction is horizontal, and the SiO ₂ precursor solution of 1) to 3) as the binder is placed in the bat. Injection was performed so that the liquid level was 1 mm / min in the vertical direction. The SiO ₂ precursor solution was poured into the vat until it was finally 5 mm above the upper surface of the compression molded specimen.

(3) The compression-molded test piece used in (2) was placed, and the bat filled with the SiO ₂ precursor solution was set in a vacuum vessel and gradually exhausted to about 80 Pa. The sample was left until the generation of bubbles from the surface of the compression molded test piece was reduced.

(4) The compression molded test piece was placed, the internal pressure of the vacuum vessel in which the bat filled with the SiO ₂ precursor solution was set was gradually returned to atmospheric pressure, and the compression molded test piece was taken out from the SiO ₂ precursor solution. .

(5) The compression molding test piece impregnated with the SiO ₂ precursor solution prepared in (4) is set in a vacuum drying furnace, and vacuum is applied to the compression molding test piece under the conditions of 1 to 3 Pa and 150 ° C. Heat treatment was applied.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece of 10 mm length, 10 mm width, and 5 mm thickness produced in (5).

  (7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was carried out using the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (5). For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

Regarding the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (5), the residual magnetic flux density can be improved by 20-30% compared to the resin-containing bond magnet (Comparative Example 1). , and the demagnetization curve was measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. Further, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere is 3.0% for the SiO ₂ impregnated bonded magnet, which is smaller than the thermal demagnetization factor (5%) without SiO ₂ impregnation. Furthermore, the irreversible heat demagnetization rate is also maintained in the atmosphere at 200 ° C. for 1 hour,
It is 1% or less after the SiO ₂ impregnation heat treatment and is smaller than a value close to 3% in the case of no SiO ₂ impregnation. This is because SiO ₂ suppresses deterioration due to oxidation of magnetic powder.

The bending strength of the compression molded test piece of 15 mm in length, 10 mm in width, and 2 mm in thickness produced in (7) is ₂ MPa or less before SiO ₂ impregnation, but has a bending strength of 100 MPa or more after heat treatment with SiO ₂ impregnation. It was possible to make a body.

  The specific resistance of the magnet was about 10 times that of the sintered rare earth magnet, but about 1/10 that of the compressed rare earth bonded magnet. became. However, this decrease in resistance is not a big problem. For example, when it is used as a self-starting permanent magnet synchronous motor, the eddy current loss increases slightly, but it does not become a problem that hinders use.

From the results of this example, the rare earth bonded magnet impregnated in the rare earth magnet molded body produced by the cold forming method without using the low-viscosity SiO ₂ precursor of the present invention is compared with a normal resin-containing rare earth bonded magnet. As a result, it was found that the magnetic properties are 20-30%, the bending strength is 2-3 times, the irreversible thermal demagnetization rate is reduced to less than half, and the magnet can be highly reliable.

In this example, magnetic powder obtained by pulverizing a NdFeB-based ribbon similar to [Example 1] was used for the rare earth magnet magnetic powder. The following three solutions were used for the SiO ₂ precursor as a binder.

1) Mix CH ₃ O— (Si (CH ₃ O) ₂ —O) —CH ₃ with 25 ml, water 5.9 ml, dehydrated methyl alcohol 75 ml, dibutyltin dilaurate 0.05 ml Left alone.

2) 25 ml of C ₂ H ₅ O— (Si (C ₂ H ₅ O) ₂ —O) —CH ₃ , 4.3 ml of water, 75 ml of dehydrated ethyl alcohol, and 0.05 ml of dibutyltin dilaurate were mixed for 3 days and nights. It was left at a temperature of 25 ° C.

_{3) n-C 3 H 7} O- (Si (C 2 H 5 O) 2 -O) -n-C 3 a H ₇ 25 ml, water 3.4 ml, dried iso- propyl alcohol 75 ml, dibutyltin dilaurate 0 0.05 ml was mixed and left at a temperature of 25 ° C. for 6 days and nights.

The viscosities of the SiO ₂ precursor solutions 1) to 3) were measured at a temperature of 30 ° C. using an Ostwald viscometer.

(1) The above Nd ₂ Fe ₁₄ B magnetic powder is filled in a mold, and a test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm is used for measuring magnetic properties at a pressure of 16 t / cm ² . A compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared.

(2) The compression molded test piece prepared in (1) is placed in the bat so that the pressing direction is horizontal, and the SiO ₂ precursor solution of 1) to 3) as the binder is placed in the bat. Liquid level is 1 in the vertical direction
Injection was performed so as to be mm / min. The SiO ₂ precursor solution was poured into the vat until it was finally 5 mm above the upper surface of the compression molded specimen.

(3) The compression-molded test piece used in (2) was placed, and the bat filled with the SiO ₂ precursor solution was set in a vacuum vessel and gradually exhausted to about 80 Pa. The sample was left until the generation of bubbles from the surface of the compression molded test piece was reduced.

(4) The compression molded test piece was placed, the internal pressure of the vacuum vessel in which the bat filled with the SiO ₂ precursor solution was set was gradually returned to atmospheric pressure, and the compression molded test piece was taken out from the SiO ₂ precursor solution. .

(5) The compression molding test piece impregnated with the SiO ₂ precursor solution prepared in (4) is set in a vacuum drying furnace, and vacuum is applied to the compression molding test piece under the conditions of 1 to 3 Pa and 150 ° C. Heat treatment was applied.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece of 10 mm length, 10 mm width, and 5 mm thickness produced in (5).

(7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was carried out using the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (5). For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

Regarding the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (5), the residual magnetic flux density can be improved by 20-30% compared to the resin-containing bond magnet (Comparative Example 1). , and the demagnetization curve was measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. Further, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere is 3.0% for the SiO ₂ impregnated bonded magnet, which is smaller than the thermal demagnetization factor (5%) without SiO ₂ impregnation. Furthermore, the irreversible heat demagnetization rate is also maintained in the atmosphere at 200 ° C. for 1 hour,
It is 1% or less after the SiO ₂ impregnation heat treatment and is smaller than a value close to 3% in the case of no SiO ₂ impregnation. This is because SiO ₂ suppresses deterioration due to oxidation of magnetic powder.

The bending strength of the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (7) is ₂ MPa or less before SiO ₂ impregnation, but has a bending strength of 80 MPa or more after SiO ₂ impregnation heat treatment. It was possible to make a body.

  The specific resistance of the magnet was about 10 times that of the sintered rare earth magnet, but about 1/10 that of the compressed rare earth bonded magnet. became. Although the generation of eddy current loss is slightly increased, such a decrease in resistance value is not a problem.

From the results of this example, the rare earth bonded magnet impregnated in the rare earth magnet molded body produced by the cold forming method without using the low-viscosity SiO ₂ precursor of the present invention is compared with a normal resin-containing rare earth bonded magnet. Thus, it has been found that the magnetic properties are 20-30%, the bending strength is about twice, the irreversible thermal demagnetization rate can be reduced to less than half, and the magnet can be highly reliable.

In this example, magnetic powder obtained by pulverizing a NdFeB-based ribbon similar to [Example 1] was used for the rare earth magnet magnetic powder. The following three solutions were used for the SiO ₂ precursor as a binder.

1) 25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, average is 4), 9.6 ml of water, 75 ml of dehydrated methyl alcohol, dibutyltin dilaurate 0 0.05 ml was mixed and left at a temperature of 25 ° C. overnight.

_{2) CH 3 O- (Si (} CH 3 O) 2 -O) m -CH 3 (m is 3-5, average 4) 25 ml, water 9.6 ml, dehydrated methanol 75 ml, dibutyltin dilaurate 0 0.05 ml was mixed and left at a temperature of 25 ° C. for 2 days and nights.

_{3) CH 3 O- (Si (} CH 3 O) 2 -O) m -CH 3 (m is 3-5, average 4) 100 ml, water 9.6 ml, dehydrated methanol 75 ml, dibutyltin dilaurate 0 0.05 ml was mixed and left at a temperature of 25 ° C. for 4 days.

The viscosities of the SiO ₂ precursor solutions 1) to 3) were measured at a temperature of 30 ° C. using an Ostwald viscometer.

(1) The above Nd ₂ Fe ₁₄ B magnetic powder is filled in a mold, and a test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm is used for measuring magnetic properties at a pressure of 16 t / cm ² . A compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared.

(2) The compression molded test piece prepared in (1) is placed in the bat so that the pressing direction is horizontal, and the SiO ₂ precursor solution of 1) to 3) as the binder is placed in the bat. Liquid level is 1 in the vertical direction
Injection was performed so as to be mm / min. The SiO ₂ precursor solution was poured into the vat until it was finally 5 mm above the upper surface of the compression molded specimen.

(3) The compression-molded test piece used in (2) was placed, and the bat filled with the SiO ₂ precursor solution was set in a vacuum vessel and gradually exhausted to about 80 Pa. The sample was left until the generation of bubbles from the surface of the compression molded test piece was reduced.

(4) The compression molded test piece was placed, the internal pressure of the vacuum vessel in which the bat filled with the SiO ₂ precursor solution was set was gradually returned to atmospheric pressure, and the compression molded test piece was taken out from the SiO ₂ precursor solution. .

(5) The compression molding test piece impregnated with the SiO ₂ precursor solution prepared in (4) is set in a vacuum drying furnace, and vacuum is applied to the compression molding test piece under the conditions of 1 to 3 Pa and 150 ° C. Heat treatment was applied.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece of 10 mm length, 10 mm width, and 5 mm thickness produced in (5).

  (7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was carried out using the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (5). For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

Regarding the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (5) above, the residual magnetic flux density is improved by 20-30% compared to the resin-containing bond magnet (Comparative Example 1). are possible, the demagnetization curve was measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. Further, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere is 3.0% for the SiO ₂ impregnated bonded magnet, which is smaller than the thermal demagnetization factor (5%) without SiO ₂ impregnation. Further, the irreversible thermal demagnetization rate is 1% or less after the SiO ₂ impregnation heat treatment after being held in the atmosphere at 200 ° C. for 1 hour, and is smaller than the value close to 3% in the case of no SiO ₂ impregnation. This is because SiO ₂ suppresses deterioration due to oxidation of magnetic powder.

The bending strength of the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (7) above is ₂ MPa or less before SiO ₂ impregnation, but has a bending strength of 130 MPa or more after SiO ₂ impregnation heat treatment. It was possible to produce a molded body.

  The specific resistance of the magnet was about 10 times that of the sintered rare earth magnet, but about 1/10 that of the compressed rare earth bonded magnet. became. Although the generation of eddy current loss is slightly increased, such a decrease in resistance value is not a problem.

From the results of this example, the rare earth bonded magnet impregnated in the rare earth magnet molded body produced by the cold forming method without using the low-viscosity SiO ₂ precursor of the present invention is compared with a normal resin-containing rare earth bonded magnet. As a result, it was found that the magnetic properties are 20-30%, the bending strength is 3-4 times, the irreversible thermal demagnetization rate can be reduced to less than half and the magnet can be highly reliable.

In this example, magnetic powder obtained by pulverizing a NdFeB-based ribbon similar to [Example 1] was used for the rare earth magnet magnetic powder. A treatment liquid for forming a rare earth fluoride or alkaline earth metal fluoride coating film was prepared as follows.
(1) A salt having high solubility in water, for example, in the case of La, acetic acid La or nitric acid La 4 g was introduced into 100 ml of water, and completely dissolved using a shaker or an ultrasonic stirrer.
(2) The equivalent of the chemical reaction in which LaF ₃ produces hydrofluoric acid diluted to 10% was gradually added.
(3) The solution in which LaF ₃ of gelled precipitate was formed was stirred for 1 hour or more using an ultrasonic stirrer.
(4) After centrifugation at 4000 to 6000 rpm, the supernatant was removed and the same amount of methanol was added.
(5) A methanol solution containing gelled LaF ₃ was stirred to make a complete suspension, and then stirred for 1 hour or more using an ultrasonic stirrer.
(6) The operations of (4) and (5) were repeated 3 to 10 times until no anion such as acetate ion or nitrate ion was detected.
(7) When finally LaF _3, was the LaF ₃ almost transparent sol-like. As the treatment liquid, a methanol solution containing 1 g / 5 ml of LaF ₃ was used.

  The other rare earth fluoride or alkaline earth metal fluoride coating film forming treatment liquids are summarized in Table 3.

The process of forming the rare earth fluoride or alkaline earth metal fluoride coat film on the magnetic powder of Nd ₂ Fe ₁₄ B was carried out by the following method.

In the case of NdF ₃ coat film forming process: NdF ₃ concentration 1 g / 10 ml translucent sol solution (1) Add 15 ml of NdF ₃ coat film forming treatment liquid to 100 g of magnetic powder obtained by pulverizing NdFeB-based ribbon. The mixing was performed until it was confirmed that the entire magnetic powder for rare earth magnet was wet.
(2) The methanol powder of the rare earth magnet subjected to the NdF ₃ coat film forming treatment of (1) was subjected to methanol removal under a reduced pressure of 2 to 5 torr.
(3) The rare earth magnet magnetic powder from which the solvent of (2) was removed was transferred to a quartz boat and subjected to heat treatment at 200 ° C. for 30 minutes and 400 ° C. for 30 minutes under a reduced pressure of 1 × 10 ⁻⁵ torr. .
(4) The magnetic powder heat-treated in (3) is transferred to a Macor lidded lid (manufactured by Riken Denshi Co., Ltd.) and then heat-treated at 700 ° C. for 30 minutes under a reduced pressure of 1 × 10 ⁻⁵ torr. It was.

For the SiO ₂ precursor as a binder, 25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, the average is 4), 4.8 ml of water, dehydration A solution obtained by mixing 75 ml of methyl alcohol and 0.05 ml of dibutyltin dilaurate and leaving it at a temperature of 25 ° C. for 2 days and nights was used.

(1) Nd ₂ Fe ₁₄ B magnetic powder coated with the above rare earth fluoride or alkaline earth metal fluoride coating film is filled in a mold, and is 10 mm in length and 16 mm in width for measuring magnetic properties at a pressure of 16 t / cm ^2. A test piece having a thickness of 10 mm and a thickness of 5 mm was prepared, and a compression test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared for strength measurement.

(2) The SiO ₂ precursor solution, which is a binder, placed in a bat so that the pressing direction is in the horizontal direction and left at a temperature of 25 ° C. for two days and nights. Was injected into the vat so that the liquid level was 1 mm / min in the vertical direction. The SiO ₂ precursor solution was poured into the vat until it was finally 5 mm above the upper surface of the compression molded specimen.

(3) The compression molding test piece used in the above (2) was arranged, and a bat filled with the SiO ₂ precursor solution was set in a vacuum vessel and gradually exhausted to about 80 Pa. The sample was left until the generation of bubbles from the surface of the compression molded test piece was reduced.

(4) The compression molded test piece was placed, the internal pressure of the vacuum vessel in which the bat filled with the SiO ₂ precursor solution was set was gradually returned to atmospheric pressure, and the compression molded test piece was taken out from the SiO ₂ precursor solution. .

(5) The compression molding test piece impregnated with the SiO ₂ precursor solution prepared in the above (4) is set in a vacuum drying furnace, and the compression molding test piece is subjected to a pressure of 1 to 3 Pa at 150 ° C. Vacuum heat treatment was applied.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm produced in the above (5).

  (7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was performed using the compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm prepared in (5) above. For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

Regarding the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (5) above, the residual magnetic flux density is improved by 20-30% compared to the resin-containing bond magnet (Comparative Example 1). are possible, the demagnetization curve was measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. Further, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere is 3.0% for the SiO ₂ impregnated bonded magnet, which is smaller than the thermal demagnetization factor (5%) without SiO ₂ impregnation. Further, the irreversible thermal demagnetization rate is 1% or less after the SiO ₂ impregnation heat treatment after being held in the atmosphere at 200 ° C. for 1 hour, and is smaller than the value close to 3% in the case of no SiO ₂ impregnation. This is because SiO ₂ suppresses deterioration due to oxidation of magnetic powder.

The magnet using the rare earth magnetic powder formed with the rare earth fluoride or alkaline earth metal fluoride coating film of this embodiment not only functions as an insulating film described later, but also uses TbF ₃ and DyF ₃ , and although the effect is small, PrF It was found that when ₃ was used for coating film formation, it could contribute to the improvement of the coercive force of the magnet.

The bending strength of the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (7) above is ₂ MPa or less before SiO ₂ impregnation, but has a bending strength of 50 MPa or more after SiO ₂ impregnation heat treatment. It was possible to produce a molded body.

  Further, the specific resistance of the magnet is about 100 times or more that of the sintered type rare earth magnet, and is equivalent to that of the compressed type rare earth bonded magnet. . Therefore, the eddy current loss is small, and it has good characteristics.

From the results of this example, the rare earth bonded magnet impregnated in the rare earth magnet molded body produced by the cold forming method without using the low-viscosity SiO ₂ precursor of the present invention is compared with a normal resin-containing rare earth bonded magnet. In addition, the magnetic properties are about 20%, the bending strength is equivalent to 3 times, the irreversible thermal demagnetization rate can be reduced to less than half, and the magnet can be made more reliable, and TbF ₃ and DyF ₃ are coated. It was found that the magnetic properties can be greatly improved when used for formation.

In this example, a magnetic powder obtained by pulverizing an NdFeB-based ribbon similar to [Example 1] was used. The process of forming the rare earth fluoride or alkaline earth metal fluoride coat film on the magnetic powder of Nd ₂ Fe ₁₄ B was carried out by the following method.

In the case of the PrF ₃ coat film forming process: A PrF ₃ concentration of 0.1 g / 10 ml translucent sol solution was used.
(1) 1 to 30 ml of PrF ₃ coat film forming treatment liquid was added to 100 g of magnetic powder obtained by pulverizing NdFeB-based ribbon, and mixed until it was confirmed that the entire magnetic powder for rare earth magnets was wet.
(2) Methanol was removed from the solvent of the rare earth magnet magnetic powder subjected to the PrF ₃ coat film forming treatment of (1) above under a reduced pressure of 2 to 5 torr.
(3) The magnetic powder for rare earth magnets from which the solvent of (2) has been removed is transferred to a quartz boat and 1 ×
Heat treatment was performed at 200 ° C. for 30 minutes and 400 ° C. for 30 minutes under a reduced pressure of 10 ⁻⁵ torr.
(4) After the magnetic powder heat-treated in (3) above is transferred to a lid made by Macor (manufactured by Riken Denshi), heat treatment is performed at 700 ° C. for 30 minutes under a reduced pressure of 1 × 10 ⁻⁵ torr. went.

For the SiO ₂ precursor as a binder, 25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, the average is 4), 4.8 ml of water, dehydration A solution obtained by mixing 75 ml of methyl alcohol and 0.05 ml of dibutyltin dilaurate and leaving it at a temperature of 25 ° C. for 2 days and nights was used.

(1) Nd ₂ Fe ₁₄ B magnetic powder coated with the above PrF ₃ coating film is filled in a mold, and a test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm is used for measuring magnetic properties at a pressure of 16 t / cm ^2. Also, a compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared for strength measurement.

(2) The SiO ₂ precursor solution, which is a binder, placed in a bat so that the pressing direction is in the horizontal direction and left at a temperature of 25 ° C. for two days and nights. Was injected into the vat so that the liquid level was 1 mm / min in the vertical direction. The SiO ₂ precursor solution was poured into the vat until it was finally 5 mm above the upper surface of the compression molded specimen.

(3) The compression molding test piece used in the above (2) was arranged, and a bat filled with the SiO ₂ precursor solution was set in a vacuum vessel and gradually exhausted to about 80 Pa. The sample was left until the generation of bubbles from the surface of the compression molded test piece was reduced.

(4) The compression molded test piece was placed, the internal pressure of the vacuum vessel in which the bat filled with the SiO ₂ precursor solution was set was gradually returned to atmospheric pressure, and the compression molded test piece was taken out from the SiO ₂ precursor solution. .

(5) The compression molding test piece impregnated with the SiO ₂ precursor solution prepared in the above (4) is set in a vacuum drying furnace, and the compression molding test piece is subjected to a pressure of 1 to 3 Pa at 150 ° C. Vacuum heat treatment was applied.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm produced in the above (5).

  (7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was performed using the compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm prepared in (5) above. For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

Regarding the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (5) above, the residual magnetic flux density is improved by 20-30% compared to the resin-containing bond magnet (Comparative Example 1). are possible, the demagnetization curve was measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. Further, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere is 3.0% for the SiO ₂ impregnated bonded magnet, which is smaller than the thermal demagnetization factor (5%) without SiO ₂ impregnation. Further, the irreversible thermal demagnetization rate is 1% or less after the SiO ₂ impregnation heat treatment after being held in the atmosphere at 200 ° C. for 1 hour, and is smaller than the value close to 3% in the case of no SiO ₂ impregnation. This is because SiO ₂ suppresses deterioration due to oxidation of magnetic powder.

It was found that the magnet using the rare earth magnetic powder formed with the PrF ₃ coat film of this example not only functions as an insulating film to be described later, but can contribute to the improvement of the coercive force of the magnet although the effect is small.

The bending strength of the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (7) above is ₂ MPa or less before SiO ₂ impregnation, but has a bending strength of 100 MPa or more after SiO ₂ impregnation heat treatment. It was possible to produce a molded body.

  Further, the specific resistance of the magnet is about 100 times or more that of the sintered type rare earth magnet, and is equivalent to that of the compressed type rare earth bonded magnet. . Therefore, the occurrence of eddy current loss is small and it has good characteristics.

From the results of this example, the rare earth bonded magnet impregnated in the rare earth magnet molded body produced by the cold forming method without using the low-viscosity SiO ₂ precursor of the present invention is compared with a normal resin-containing rare earth bonded magnet. In addition, the magnetic properties are about 20%, the bending strength is 2 to 3 times, the irreversible thermal demagnetization rate can be reduced to less than half and the magnet can be highly reliable, and PrF ₃ is used for forming the coating film. It was found that magnetic characteristics can be improved at times. It was found that a magnet using rare earth magnetic powder formed with a coating film of PrF ₃ is a well-balanced magnet with improved overall magnetic properties, bending strength and reliability.

In this example, a magnetic powder obtained by pulverizing an NdFeB-based ribbon similar to [Example 1] was used. The process of forming the rare earth fluoride or alkaline earth metal fluoride coat film on the magnetic powder of Nd ₂ Fe ₁₄ B was carried out by the following method.

In the case of the DyF ₃ coat film formation process: A DyF ₃ concentration of 2 to 0.01 g / 10 ml of a translucent sol solution was used.
(1) 10 ml of DyF ₃ coat film forming solution was added to 100 g of magnetic powder obtained by pulverizing NdFeB-based ribbon, and mixed until it was confirmed that the entire magnetic powder for rare earth magnet was wetted.
(2) The methanol of the solvent was removed from the rare earth magnet magnetic powder that had been subjected to the DyF ₃ coat film forming process of (1) above under a reduced pressure of 2 to 5 torr.
(3) The magnetic powder for rare earth magnets from which the solvent of (2) has been removed is transferred to a quartz boat and 1 ×
Heat treatment was performed at 200 ° C. for 30 minutes and 400 ° C. for 30 minutes under a reduced pressure of 10 ⁻⁵ torr.
(4) After the magnetic powder heat-treated in (3) above is transferred to a lid made by Macor (manufactured by Riken Denshi), heat treatment is performed at 700 ° C. for 30 minutes under a reduced pressure of 1 × 10 ⁻⁵ torr. went.

For the SiO ₂ precursor as a binder, 25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, the average is 4), 4.8 ml of water, dehydration A solution obtained by mixing 75 ml of methyl alcohol and 0.05 ml of dibutyltin dilaurate and leaving it at a temperature of 25 ° C. for 2 days and nights was used.

(1) Nd ₂ Fe ₁₄ B magnetic powder coated with the above DyF ₃ coating film is filled in a mold, and a test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm is used for measuring magnetic properties at a pressure of 16 t / cm ^2. Also, a compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared for strength measurement.

(2) The SiO ₂ precursor solution, which is a binder, placed in a bat so that the pressing direction is in the horizontal direction and left at a temperature of 25 ° C. for two days and nights. Was injected into the vat so that the liquid level was 1 mm / min in the vertical direction. The SiO ₂ precursor solution was poured into the vat until it was finally 5 mm above the upper surface of the compression molded specimen.

(3) The compression molding test piece used in the above (2) was arranged, and a bat filled with the SiO ₂ precursor solution was set in a vacuum vessel and gradually exhausted to about 80 Pa. The sample was left until the generation of bubbles from the surface of the compression molded test piece was reduced.

(4) The compression molded test piece was placed, the internal pressure of the vacuum vessel in which the bat filled with the SiO ₂ precursor solution was set was gradually returned to atmospheric pressure, and the compression molded test piece was taken out from the SiO ₂ precursor solution. .

(5) The compression molding test piece impregnated with the SiO ₂ precursor solution prepared in the above (4) is set in a vacuum drying furnace, and the compression molding test piece is subjected to a pressure of 1 to 3 Pa at 150 ° C. Vacuum heat treatment was applied.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm produced in the above (5).

  (7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was performed using the compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm prepared in (5) above. For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

Regarding the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (5) above, the residual magnetic flux density is improved by 20-30% compared to the resin-containing bond magnet (Comparative Example 1). are possible, the demagnetization curve was measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. Further, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere is 3.0% for the SiO ₂ impregnated bonded magnet, which is smaller than the thermal demagnetization factor (5%) without SiO ₂ impregnation. Further, the irreversible thermal demagnetization rate is 1% or less after the SiO ₂ impregnation heat treatment after being held in the atmosphere at 200 ° C. for 1 hour, and is smaller than the value close to 3% in the case of no SiO ₂ impregnation. This is because SiO ₂ suppresses deterioration due to oxidation of magnetic powder.

It was found that the magnet using the rare earth magnetic powder formed with the DyF ₃ coating film of this example not only functions as an insulating film described later, but can contribute to the improvement of the coercive force of the magnet.

The bending strength of the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (7) above is ₂ MPa or less before SiO ₂ impregnation, but has a bending strength of 40 MPa or more after SiO ₂ impregnation heat treatment. It was possible to produce a molded body.

  Further, the specific resistance of the magnet is about 100 times or more that of the sintered type rare earth magnet, and the same value as that of the compression type rare earth bonded magnet. Therefore, the eddy current loss is small, and it has good characteristics.

From the results of this example, the rare earth bonded magnet impregnated in the rare earth magnet molded body produced by the cold forming method without using the low-viscosity SiO ₂ precursor of the present invention is compared with a normal resin-containing rare earth bonded magnet. In addition, the magnetic properties are about 20%, the bending strength is equivalent to 3 times, the irreversible thermal demagnetization rate can be reduced to less than half, and the magnet can be made more reliable, and TbF ₃ and DyF ₃ are coated. It was found that the magnetic properties can be greatly improved when used for formation.

  In this example, magnetic powder obtained by pulverizing a NdFeB-based ribbon similar to [Example 1] was used for the rare earth magnet magnetic powder. The treatment liquid for forming the phosphate chemical conversion film was prepared as follows.

20 g of phosphoric acid, 4 g of boric acid and 4 g of MgO, ZnO, CdO, CaO or BaO are dissolved in 1 l of water, and EF-104 (manufactured by Tochem Products), EF-122 (Tochem Products) are dissolved as surfactants. EF-132 (manufactured by Tochem Products) was added to 0.1 wt%. As rust preventives, benzotriazole (BT), imidazole (IZ), benzimidazole (BI), thiourea (TU), 2-mercaptobenzimidazole (MI), octylamine (OA), triethanolamine (TA), o-Toluidine (TL), indole (ID), and 2-methylpyrrole (MP) were added at 0.04 mol / l.

The process of forming the phosphate chemical conversion film on the magnetic powder of Nd ₂ Fe ₁₄ B was carried out by the following method. Table 4 shows the composition of the phosphating solution used.

(1) 5 ml of a phosphating solution was added to 100 g of magnetic powder obtained by pulverizing a NdFeB-based ribbon, and mixed until it was confirmed that the entire magnetic powder for rare earth magnets was wetted.
(2) The magnetic powder for a rare earth magnet subjected to the phosphating film forming treatment of (1) was heat-treated at 180 ° C. for 30 minutes under a reduced pressure of 2 to 5 torr.

The SiO ₂ precursor, which is a binder, includes 25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, average is 4), 4.8 ml of water, dehydrated A solution obtained by mixing 75 ml of methyl alcohol and 0.05 ml of dibutyltin dilaurate and leaving it at a temperature of 25 ° C. for 2 days and nights was used.

(1) Filling the mold with Nd ₂ Fe ₁₄ B magnetic powder that has been subjected to the above-mentioned phosphatization film formation treatment, and measuring the magnetic properties at a pressure of 16 t / cm ² , 10 mm long, 10 mm wide, 5 mm thick In addition, a compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared for strength measurement.

(2) The SiO ₂ precursor solution, which is a binder, placed in a bat so that the pressing direction is in the horizontal direction and left at a temperature of 25 ° C. for two days and nights. Was injected into the vat so that the liquid level was 1 mm / min in the vertical direction. The SiO ₂ precursor solution was poured into the vat until it was finally 5 mm above the upper surface of the compression molded specimen.

(3) The compression molding test piece used in the above (2) was arranged, and a bat filled with the SiO ₂ precursor solution was set in a vacuum vessel and gradually exhausted to about 80 Pa. The sample was left until the generation of bubbles from the surface of the compression molded test piece was reduced.

(4) The compression molded test piece was placed, the internal pressure of the vacuum vessel in which the bat filled with the SiO ₂ precursor solution was set was gradually returned to atmospheric pressure, and the compression molded test piece was taken out from the SiO ₂ precursor solution. .

(5) The compression molding test piece impregnated with the SiO ₂ precursor solution prepared in the above (4) is set in a vacuum drying furnace, and the compression molding test piece is subjected to a pressure of 1 to 3 Pa at 150 ° C. Vacuum heat treatment was applied.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm produced in the above (5).

  (7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was performed using the compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm prepared in (5) above. For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

Regarding the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (5), the residual magnetic flux density can be improved by 20-30% compared to the resin-containing bond magnet (Comparative Example 1). , and the demagnetization curve was measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. Further, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere is 3.0% for the SiO ₂ impregnated bonded magnet, which is smaller than the thermal demagnetization factor (5%) without SiO ₂ impregnation. Furthermore, the irreversible heat demagnetization rate is also maintained in the atmosphere at 200 ° C. for 1 hour,
It is 1% or less after the SiO ₂ impregnation heat treatment and is smaller than a value close to 3% in the case of no SiO ₂ impregnation. This is because SiO ₂ suppresses deterioration due to oxidation of magnetic powder.

The bending strength of the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (7) above is ₂ MPa or less before SiO ₂ impregnation, but has a bending strength of 100 MPa or more after SiO ₂ impregnation heat treatment. It was possible to produce a molded body.

  Further, the specific resistance of the magnet is about 100 times or more that of the sintered type rare earth magnet, and is equivalent to that of the compressed type rare earth bonded magnet. . Therefore, the eddy current loss is small, and it has good characteristics.

From the results of this example, the rare earth bonded magnet impregnated in the rare earth magnet molded body produced by the cold forming method without using the low-viscosity SiO ₂ precursor of the present invention is compared with a normal resin-containing rare earth bonded magnet. Thus, it has been found that the magnetic properties are 20-30%, the bending strength is about 3 times, the irreversible thermal demagnetization rate is reduced to less than half, and the magnet can be highly reliable.

In this example, magnetic powder obtained by pulverizing a NdFeB-based ribbon similar to [Example 1] was used for the rare earth magnet magnetic powder. The treatment liquid for forming the phosphate chemical conversion film was prepared as follows. 20 g of phosphoric acid, 4 g of boric acid and 4 g of MgO as a metal oxide were dissolved in 1 l of water, and EF-104 (manufactured by Tochem Products) was added as a surfactant to a concentration of 0.1 wt%. Benzotriazole (BT) was used as a rust preventive agent, and was added so as to have a concentration of 0.01 to 0.5 mol / l. The process of forming the phosphate chemical conversion film on the magnetic powder of Nd ₂ Fe ₁₄ B was carried out by the following method.
(1) 5 ml of a phosphating solution was added to 100 g of magnetic powder obtained by pulverizing a NdFeB-based ribbon, and mixed until it was confirmed that the entire magnetic powder for rare earth magnets was wetted.
(2) The magnetic powder for rare earth magnet subjected to the phosphatization film forming treatment of (1) above was heat-treated at 180 ° C. for 30 minutes under a reduced pressure of 2 to 5 torr.

The SiO ₂ precursor, which is a binder, contains 25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, the average is 4), 4.8 ml of water, dehydrated A solution obtained by mixing 75 ml of methyl alcohol and 0.05 ml of dibutyltin dilaurate and leaving it at a temperature of 25 ° C. for 2 days and nights was used.

(1) Filling the mold with Nd ₂ Fe ₁₄ B magnetic powder that has been subjected to the above-mentioned phosphatization film formation treatment, and measuring the magnetic properties at a pressure of 16 t / cm ² , 10 mm long, 10 mm wide, 5 mm thick In addition, a compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared for strength measurement.

(2) The SiO ₂ precursor solution, which is a binder, placed in a bat so that the pressing direction is in the horizontal direction and left at a temperature of 25 ° C. for two days and nights. Was injected into the vat so that the liquid level was 1 mm / min in the vertical direction. The SiO ₂ precursor solution was poured into the vat until it was finally 5 mm above the upper surface of the compression molded specimen.

(3) The compression molding test piece used in the above (2) was arranged, and a bat filled with the SiO ₂ precursor solution was set in a vacuum vessel and gradually exhausted to about 80 Pa. The sample was left until the generation of bubbles from the surface of the compression molded test piece was reduced.

(4) The compression molded test piece was placed, the internal pressure of the vacuum vessel in which the bat filled with the SiO ₂ precursor solution was set was gradually returned to atmospheric pressure, and the compression molded test piece was taken out from the SiO ₂ precursor solution. .

(5) The compression molding test piece impregnated with the SiO ₂ precursor solution prepared in the above (4) is set in a vacuum drying furnace, and the compression molding test piece is subjected to a pressure of 1 to 3 Pa at 150 ° C. Vacuum heat treatment was applied.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm produced in the above (5).

  (7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was performed using the compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm prepared in (5) above. For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

Regarding the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (5) above, the residual magnetic flux density is improved by 20-30% compared to the resin-containing bond magnet (Comparative Example 1). are possible, the demagnetization curve was measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. Further, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere is 3.0% for the SiO ₂ impregnated bonded magnet, which is smaller than the thermal demagnetization factor (5%) without SiO ₂ impregnation. Further, the irreversible thermal demagnetization rate is 1% or less after the SiO ₂ impregnation heat treatment after being held in the atmosphere at 200 ° C. for 1 hour, and is smaller than the value close to 3% in the case of no SiO ₂ impregnation. This is because SiO ₂ suppresses deterioration due to oxidation of magnetic powder. The bending strength of the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (7) above is ₂ MPa or less before SiO ₂ impregnation, but has a bending strength of 100 MPa or more after SiO ₂ impregnation heat treatment. It was possible to produce a molded body. Further, the specific resistance of the magnet is about 100 times or more that of the sintered type rare earth magnet, and is equivalent to that of the compressed type rare earth bonded magnet. . Therefore, the eddy current loss is small, and it has good characteristics.

From the results of this example, the rare earth bonded magnet impregnated in the rare earth magnet molded body produced by the cold forming method without using the low-viscosity SiO ₂ precursor of the present invention is compared with a normal resin-containing rare earth bonded magnet. Thus, it has been found that the magnetic properties are 20-30%, the bending strength is about 3 times, the irreversible thermal demagnetization rate is reduced to less than half, and the magnet can be highly reliable.

In this example, magnetic powder obtained by pulverizing a NdFeB-based ribbon similar to [Example 1] was used for the rare earth magnet magnetic powder. The treatment liquid for forming the phosphate chemical conversion film was prepared as follows. In 1 liter of water, 20 g of phosphoric acid, 4 g of boric acid, 4 g of MgO as a metal oxide were dissolved, and benzotriazole (BT) was added as a rust preventive to 0.04 mol / l. EF-104 (manufactured by Tochem Products) is used as a surfactant, and its concentration is 0.01 to 1.
It added so that it might become wt%. The process of forming the phosphate chemical conversion film on the magnetic powder of Nd ₂ Fe ₁₄ B was carried out by the following method.
(1) Phosphate conversion treatment solution 5 for 100 g of magnetic powder obtained by pulverizing NdFeB-based ribbon
ml was added and mixed until it was confirmed that the entire magnetic powder for rare earth magnets was wet.
(2) The magnetic powder for a rare earth magnet subjected to the phosphating film forming treatment of (1) was heat-treated at 180 ° C. for 30 minutes under a reduced pressure of 2 to 5 torr.

The SiO ₂ precursor, which is a binder, includes 25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, the average is 4), 4.8 ml of water, and dehydration. A solution obtained by mixing 75 ml of methyl alcohol and 0.05 ml of dibutyltin dilaurate and leaving it at a temperature of 25 ° C. for 2 days and nights was used.

(1) Filling the mold with Nd ₂ Fe ₁₄ B magnetic powder that has been subjected to the above-mentioned phosphatization film formation treatment, and measuring the magnetic properties at a pressure of 16 t / cm ² , the length is 10 mm, the width is 10 mm, and the thickness is 5 mm. In addition, a compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared for strength measurement.

(2) The SiO ₂ precursor solution, which is a binder, placed in a bat so that the pressing direction is in the horizontal direction and left at a temperature of 25 ° C. for two days and nights. Was injected into the vat so that the liquid level was 1 mm / min in the vertical direction. The SiO ₂ precursor solution was poured into the vat until it was finally 5 mm above the upper surface of the compression molded specimen.

(3) The compression molding test piece used in the above (2) was arranged, and a bat filled with the SiO ₂ precursor solution was set in a vacuum vessel and gradually exhausted to about 80 Pa. The sample was left until the generation of bubbles from the surface of the compression molded test piece was reduced.

(4) The compression molding test piece is arranged, and the internal pressure of the vacuum vessel in which the bat filled with the SiO ₂ precursor solution is set is gradually returned to the atmospheric pressure, and the compression molding test piece is taken out from the SiO ₂ precursor solution. did.

(5) The compression molding test piece impregnated with the SiO ₂ precursor solution prepared in the above (4) is set in a vacuum drying furnace, and the compression molding test piece is subjected to a pressure of 1 to 3 Pa at 150 ° C. Vacuum heat treatment was applied.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm produced in the above (5).

  (7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was performed using the compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm prepared in (5) above. For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

Regarding the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (5), the residual magnetic flux density can be improved by 20-30% compared to the resin-containing bond magnet (Comparative Example 1). , and the demagnetization curve was measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. Further, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere is 3.0% for the SiO ₂ impregnated bonded magnet, which is smaller than the thermal demagnetization factor (5%) without SiO ₂ impregnation. Furthermore, the irreversible heat demagnetization rate is also maintained in the atmosphere at 200 ° C. for 1 hour,
It is 1% or less after the SiO ₂ impregnation heat treatment and is smaller than a value close to 3% in the case of no SiO ₂ impregnation. This is because SiO ₂ suppresses deterioration due to oxidation of magnetic powder.

The bending strength of the compression-molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (7) above is ₂ MPa or less before SiO ₂ impregnation, but has a bending strength of 90 MPa or more after SiO ₂ impregnation heat treatment. It was possible to produce a molded body.

  Further, the specific resistance of the magnet is about 100 times or more that of the sintered type rare earth magnet, and is equivalent to that of the compressed type rare earth bonded magnet. . Therefore, the eddy current loss is small, and it has good characteristics.

From the results of this example, the rare earth bonded magnet impregnated in the rare earth magnet molded body produced by the cold forming method without using the low-viscosity SiO ₂ precursor of the present invention is compared with a normal resin-containing rare earth bonded magnet. Thus, it has been found that the magnetic properties are 20-30%, the bending strength is about 3 times, the irreversible thermal demagnetization rate is reduced to less than half, and the magnet can be highly reliable.

  In this example, magnetic powder obtained by pulverizing a NdFeB-based ribbon similar to [Example 1] was used for the rare earth magnet magnetic powder.

The treatment liquid for forming the phosphate chemical conversion film was prepared as follows. Dissolve 20 g of phosphoric acid, 4 g of boric acid, 4 g of MgO as a metal oxide in 1 l of water, and use EF- as a surfactant.
104 wt. (Made by Tochem Products), 0.1 wt%, benzotriazole as rust inhibitor
(BT) was added to 0.04 mol / l. The process of forming the phosphate chemical conversion film on the magnetic powder of Nd ₂ Fe ₁₄ B was performed by the following method.
(1) 2.5 to 30 ml of phosphating solution was added to 100 g of magnetic powder obtained by pulverizing a NdFeB-based ribbon, and mixed until it was confirmed that the entire magnetic powder for rare earth magnets was wet.
(2) The magnetic powder for a rare earth magnet subjected to the phosphating film forming treatment of (1) was heat-treated at 180 ° C. for 30 minutes under a reduced pressure of 2 to 5 torr.

The SiO ₂ precursor, which is a binder, includes 25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, the average is 4), 4.8 ml of water, and dehydration. A solution obtained by mixing 75 ml of methyl alcohol and 0.05 ml of dibutyltin dilaurate and leaving it at a temperature of 25 ° C. for 2 days and nights was used.

(1) Filling the mold with Nd ₂ Fe ₁₄ B magnetic powder that has been subjected to the above-mentioned phosphatization film formation treatment, and measuring the magnetic properties at a pressure of 16 t / cm ² , 10 mm long, 10 mm wide, 5 mm thick In addition, a compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared for strength measurement.

(2) The SiO ₂ precursor solution, which is a binder, placed in a bat so that the pressing direction is in the horizontal direction and left at a temperature of 25 ° C. for two days and nights. Was injected into the vat so that the liquid level was 1 mm / min in the vertical direction. The SiO ₂ precursor solution was poured into the vat until it was finally 5 mm above the upper surface of the compression molded specimen.

(3) The compression molding test piece used in the above (2) was arranged, and a bat filled with the SiO ₂ precursor solution was set in a vacuum vessel and gradually exhausted to about 80 Pa. The sample was left until the generation of bubbles from the surface of the compression molded test piece was reduced.

(4) The compression molded test piece was placed, the internal pressure of the vacuum vessel in which the bat filled with the SiO ₂ precursor solution was set was gradually returned to atmospheric pressure, and the compression molded test piece was taken out from the SiO ₂ precursor solution. .

(5) The compression molding test piece impregnated with the SiO ₂ precursor solution prepared in the above (4) is set in a vacuum drying furnace, and the compression molding test piece is subjected to a pressure of 1 to 3 Pa at 150 ° C. Vacuum heat treatment was applied.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm produced in the above (5).

  (7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was performed using the compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm prepared in (5) above. For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

Regarding the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (5) above, the residual magnetic flux density is improved by 20-30% compared to the resin-containing bond magnet (Comparative Example 1). are possible, the demagnetization curve was measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. Further, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere is 3.0% for the SiO ₂ impregnated bonded magnet, which is smaller than the thermal demagnetization factor (5%) without SiO ₂ impregnation. Further, the irreversible thermal demagnetization rate is 1% or less after the SiO ₂ impregnation heat treatment after being held in the atmosphere at 200 ° C. for 1 hour, and is smaller than the value close to 3% in the case of no SiO ₂ impregnation. This is because SiO ₂ suppresses deterioration due to oxidation of magnetic powder.

The bending strength of the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (7) above is ₂ MPa or less before SiO ₂ impregnation, but has a bending strength of 100 MPa or more after SiO ₂ impregnation heat treatment. It was possible to produce a molded body.

  Further, the specific resistance of the magnet is about 100 times or more that of the sintered type rare earth magnet, and is equivalent to that of the compressed type rare earth bonded magnet. . Therefore, the eddy current loss is small, and it has good characteristics.

From the results of this example, the rare earth bonded magnet impregnated in the rare earth magnet molded body produced by the cold forming method without using the low-viscosity SiO ₂ precursor of the present invention is compared with a normal resin-containing rare earth bonded magnet. Thus, it has been found that the magnetic properties are 20-30%, the bending strength is about 3 times, the irreversible thermal demagnetization rate is reduced to less than half, and the magnet can be highly reliable.
(Comparative Example 1)
In this comparative example, magnetic powder obtained by pulverizing an NdFeB-based ribbon similar to [Example 1] was used for the rare earth magnet magnetic powder.

  (1) The rare earth magnet magnetic powder and a solid epoxy resin having a size of 100 μm or less (EPX6136 manufactured by Somaru) were mixed using a V mixer so that the volume might be 0 to 20%.

(2) The rare earth magnet magnetic powder produced in (1) above and a compound of resin were loaded into a mold and subjected to heat compression molding at 80 ° C. in an inert gas atmosphere under a molding pressure of 16 t / cm ² . . The produced magnet is 10 mm long, 10 mm wide and 5 mm thick for measuring magnetic properties, and 15 mm long, 10 mm wide and 2 mm thick for measuring strength.

  (3) Resin curing of the bonded magnet produced in (2) was performed in a nitrogen gas at 170 ° C. for 1 hour.

  (4) The specific resistance was measured by the four-probe method on the compression molded test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm produced in the above (3).

  (5) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (6) A mechanical bending test was performed using the compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm produced in (3) above. For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

The magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in the above (4) were examined. As a result, the residual magnetic flux density of the magnet decreased as the epoxy resin content in the magnet increased. Compared with the bonded magnets (Examples 1 to 5) produced by impregnating the SiO ₂ binder, when compared with a magnet having a bending strength of 50 MPa or more, the epoxy resin-containing bonded magnet has a magnetic flux density of 20 to 30. % Declined. Moreover, the thermal demagnetization rate after 1 hour of holding at 200 ° C. in the air is 5% for the epoxy resin-containing bond magnet and 3.0% for the SiO ₂ impregnated bond magnet. Furthermore, the irreversible heat demagnetization rate after returning to room temperature after 1 hour at 200 ° C. and re-magnetization is less than 1% when impregnation is performed (Examples 1 to 5), whereas an epoxy resin-containing bond magnet (comparison) In the case of Example 1), the value was close to 3%. In addition to the suppression of irreversible thermal demagnetization, the epoxy resin-containing bond magnet was at a lower level than the SiO ₂ impregnated bond magnet in the PCT test and the salt spray test.

Further, the compression molded test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm produced in the above (4) was held at 225 ° C. for 1 hour in the atmosphere, and after cooling, a demagnetization curve was measured at 20 ° C. The magnetic field application direction was 10 mm. First, after magnetization with a magnetic field of +20 kOe, a magnetic field was applied alternately between ± 1 kOe and ± 10 kOe, and a demagnetization curve was measured. The result is shown in FIG. In FIG. 8, a demagnetization curve between a magnet impregnated with SiO ₂ under the condition 2) of Example 1 and a compression-bonded magnet containing 15 vol% of an epoxy resin as a binder as shown in this comparative example. Are comparing. In FIG. 8, the horizontal axis represents the applied magnetic field, and the vertical axis represents the magnetic flux density. In the magnet impregnated with the SiO ₂ binder, the magnetic flux rapidly decreases when a magnetic field greater than −8 kOe is applied to the negative side. The compression-molded bonded magnet has a magnetic field whose value is smaller than that of the impregnated magnet, and the magnetic flux rapidly decreases. The magnetic field on the negative side of −5 kOe is significantly decreased. The residual magnetic flux density after applying a magnetic field of −10 kOe is 0.44 for the impregnated magnet, and 0.11 T for the compression-molded bonded magnet, and the residual magnetic flux density of the impregnated magnet is four times the value of the compression-molded bonded magnet. ing. This is because the magnetic anisotropy of the NdFeB crystals constituting each NdFeB powder is reduced by oxidizing the surface of each NdFeB powder and the crack surface of the NdFeB powder while the compression molded bonded magnet is heated at 225 ° C. This is considered to be because the coercive force decreased and the magnetization was easily reversed by applying a negative magnetic field. On the other hand, in the impregnated magnet, the NdFeB powder and the crack surface are covered with the SiO ₂ film, so that it is considered that the reduction in coercive force is small as a result of preventing oxidation during heating in the atmosphere.

The bending strength of the compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm produced in the above (7) increases the bending strength when the epoxy resin content of the binder is increased.
With a vol%, the bending strength of the magnet is 48 MPa, which is necessary for a bonded magnet. The specific resistance of the epoxy resin-containing bonded magnet was equivalent to that of the SiO ₂ impregnated bonded magnet.

From the result of this comparative example, the epoxy resin-containing rare earth bonded magnet is compared with the rare earth bonded magnet in which the low viscosity SiO ₂ precursor of the present invention is impregnated into a rare earth magnet molded body prepared by a cold forming method without a resin. Thus, it was found that the magnetic properties were 20 to 30% lower, and the irreversible thermal demagnetization rate and the reliability of the magnet were low.

In addition, in this comparative example, the evaluation result of the epoxy resin containing bond magnet which changed the volume fraction of resin (The resin volume fraction in the magnetic powder for resin and rare earth magnets) is summarized in Table 5.

(Comparative Example 2)
In this comparative example, magnetic powder obtained by pulverizing an NdFeB-based ribbon similar to [Example 1] was used for the rare earth magnet magnetic powder.

The SiO ₂ precursor as a binder includes 1 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, average is 4), 0.19 ml of water, A solution obtained by mixing 99 ml of dehydrated methyl alcohol and 0.05 ml of dibutyltin dilaurate and leaving it at a temperature of 25 ° C. for two days and nights was used.

The viscosity of the SiO ₂ precursor solution was measured at a temperature of 30 ° C. using an Ostwald viscometer.

(1) The above Nd ₂ Fe ₁₄ B magnetic powder is filled in a mold, and a test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm is used for measuring magnetic properties at a pressure of 16 t / cm ² . A compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared.

(2) The compression-molded test piece prepared in (1) above is placed in the bat so that the pressing direction is horizontal, and the SiO ₂ precursor solution as the binder is placed vertically in the bat. 1mm / direction
Injected to reach min. The SiO ₂ precursor solution was poured into the vat until it was finally 5 mm above the upper surface of the compression molded specimen.

(3) The compression molding test piece used in the above (2) was arranged, and a bat filled with the SiO ₂ precursor solution was set in a vacuum vessel and gradually exhausted to about 80 Pa. The sample was left until the generation of bubbles from the surface of the compression molded test piece was reduced.

(4) The compression molded test piece was placed, the internal pressure of the vacuum vessel in which the bat filled with the SiO ₂ precursor solution was set was gradually returned to atmospheric pressure, and the compression molded test piece was taken out from the SiO ₂ precursor solution. .

(5) The compression molding test piece impregnated with the SiO ₂ precursor solution prepared in the above (4) is set in a vacuum drying furnace, and the compression molding test piece is subjected to a pressure of 1 to 3 Pa at 150 ° C. Vacuum heat treatment was applied.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm produced in the above (5).

  (7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was performed using the compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm prepared in (5) above. For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

Regarding the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (5) above, the residual magnetic flux density is improved by 20-30% compared to the resin-containing bond magnet (Comparative Example 1). are possible, the demagnetization curve was measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. Further, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere is 3.0% for the SiO ₂ impregnated bonded magnet, which is smaller than the thermal demagnetization factor (5%) without SiO ₂ impregnation. Furthermore, the irreversible thermal demagnetization rate after returning to room temperature after 1 hour at 200 ° C. and re-magnetization was less than 1% when the impregnation treatment was performed, whereas it was close to 3% in the case of an epoxy-based bond magnet ( Comparative Example 1).

However, the bending strength of the compression molded test piece of 15 mm in length, 10 mm in width, and 2 mm in thickness produced in the above (7) is a low level, and the SiO ₂ impregnated bond magnet of this comparative example is compared with the epoxy resin-containing bond magnet. Only a value of about 1/10 was obtained. This is because the content of the SiO ₂ precursor in the binder in this comparative example is 1 vol%, which is 1 to 2 orders of magnitude less than the content of the SiO ₂ precursor in the binder in the examples. Even if the bending strength of SiO ₂ alone is large, the content in the magnet is too small.

  In conclusion, the magnet of this comparative example has a disadvantage that the magnet strength is low, and it is necessary to consider the bending strength depending on the object of use.

  Various characteristics of this comparative example and 1), 2), and (Comparative Example 4) of (Comparative Example 3) described later are summarized in Table 6.

(Comparative Example 3)
In this comparative example, magnetic powder obtained by pulverizing an NdFeB-based ribbon similar to [Example 1] was used for the rare earth magnet magnetic powder.

The following two solutions were used for the SiO ₂ precursor as a binder.

1) 25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, average is 4), water 0.19 ml, dehydrated methyl alcohol 75 ml, dibutyltin dilaurate 0 0.05 ml was mixed and left at a temperature of 25 ° C. for 2 days and nights.

_{2) CH 3 O- (Si (} CH 3 O) 2 -O) m -CH 3 (m is 3-5, average 4) 25 ml, water 24 ml, dried ethyl alcohol 75 ml, dibutyltin dilaurate 0.05ml And left at a temperature of 25 ° C. for 2 days and nights.

The viscosities of the SiO ₂ precursor solutions 1) and 2) were measured at a temperature of 30 ° C. using an Ostwald viscometer.

(1) The above Nd ₂ Fe ₁₄ B magnetic powder is filled in a mold, and a test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm is used for measuring magnetic properties at a pressure of 16 t / cm ² . A compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared.

(2) The compression molded test piece prepared in (1) above is placed in the bat so that the pressing direction is horizontal, and the SiO ₂ precursor solution of 1) and 2) as the binder is placed in the bat. The liquid surface was injected at 1 mm / min in the vertical direction. The SiO ₂ precursor solution was poured into the vat until it was finally 5 mm above the upper surface of the compression molded specimen.

(3) The compression molding test piece used in the above (2) was arranged, and a bat filled with the SiO ₂ precursor solution was set in a vacuum vessel and gradually exhausted to about 80 Pa. The sample was left until the generation of bubbles from the surface of the compression molded test piece was reduced.

(4) The compression molded test piece was placed, the internal pressure of the vacuum vessel in which the bat filled with the SiO ₂ precursor solution was set was gradually returned to atmospheric pressure, and the compression molded test piece was taken out from the SiO ₂ precursor solution. .

(5) The compression molding test piece impregnated with the SiO ₂ precursor solution prepared in the above (4) is set in a vacuum drying furnace, and the compression molding test piece is subjected to a pressure of 1 to 3 Pa at 150 ° C. Vacuum heat treatment was applied.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm produced in the above (5).

  (7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was performed using the compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm prepared in (5) above. For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

Regarding (1) of (Comparative Example 3), the residual magnetic flux density is a resin-containing bond magnet (Comparative Example 1) with respect to the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (5) above. compared to, improved 20-30% demagnetization curve measured at 20 ° C., the matching values of residual magnetic flux density and coercivity and the molded body after the SiO ₂ before impregnated and SiO ₂ infiltration and heating almost did. Further, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere is 3.0% for the SiO ₂ impregnated bonded magnet, which is smaller than the thermal demagnetization factor (5%) without SiO ₂ impregnation. Further, the irreversible thermal demagnetization rate after returning to room temperature after 1 hour at 200 ° C. and re-magnetization is less than 1% when the impregnation treatment is performed, whereas the value is close to 3% in the case of the epoxy bond magnet (Comparative Example 1). Met.

However, the bending strength of the compression molded test piece of 15 mm in length, 10 mm in width, and 2 mm in thickness produced in the above (7) is a low level, and the SiO ₂ impregnated bond magnet of this comparative example is compared with the epoxy resin-containing bond magnet. Only a value of about 1/6 was obtained. This is because the amount of water added in the binder in this comparative example is small, so the hydrolysis of the methoxy group in the SiO ₂ precursor material shown in chemical reaction formula 1 does not proceed, so silanol groups do not form, and SiO 2 _This is because the dehydration condensation reaction between silanol groups in the thermosetting reaction of the _two precursors does not occur, so that the amount of SiO ₂ generated after thermosetting is small and the bending strength of the SiO ₂ -impregnated bonded magnet is low.

  In conclusion, since the magnet of 1) of (Comparative Example 3) has a low magnet strength, it is desirable to use it in consideration of the relationship of the magnet strength in the object of use.

Regarding (2) of (Comparative Example 3), the bending strength of the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (7) is ₂ MPa or less before the SiO ₂ impregnation, but after the SiO ₂ impregnation heat treatment Was able to produce a magnet compact having a bending strength of 170 MPa.

Regarding the magnetic characteristics of the compression molded test piece of 10mm length, 10mm width and 5mm thickness produced in (5), the residual magnetic flux density can be improved by 20% compared to the resin-containing bond magnet (Comparative Example 1). the demagnetization curve measured at 20 ° C. the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with a shaped body after SiO ₂ infiltration and heating were almost the same. However, the thermal demagnetization rate after 1 hour of holding at 200 ° C. in the atmosphere was 4.0% in this comparative example, which was a large value compared to 3.0% in the SiO ₂ impregnated bonded magnet in the example. Further, the irreversible thermal demagnetization rate after returning to room temperature after 1 hour at 200 ° C. and re-magnetization is less than 1% when the SiO ₂ impregnation treatment is performed in the example, whereas in this comparative example, the value is close to 2%. Met. This was found to be due to the fact that the SiO ₂ precursor solution penetrated into the magnet only up to about 1 mm from the magnet surface. Therefore, the magnetic powder in the central part of the magnet causes oxidative deterioration during heating in the atmosphere, which is the reason why the magnet of this comparative example has a larger irreversible heat demagnetization rate than the magnet of the example.

From this result, although the bonded magnet of this comparative example is not inferior to the conventional epoxy-based bonded magnet, the long-term reliability may be lower than that of the conventional epoxy-based bonded magnet. It is desirable to use it in consideration of oxidative deterioration in the object of use.
(Comparative Example 4)
In this comparative example, magnetic powder obtained by pulverizing an NdFeB-based ribbon similar to [Example 1] was used for the rare earth magnet magnetic powder. For the SiO ₂ precursor as a binder, 25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, the average is 4), 9.6 ml of water, dehydration A solution prepared by mixing 75 ml of methyl alcohol and 0.05 ml of dibutyltin dilaurate and leaving it at a temperature of 25 ° C. for 6 days and nights was used. The viscosity of the SiO ₂ precursor solution was measured at a temperature of 30 ° C. using an Ostwald viscometer.

(1) The above Nd ₂ Fe ₁₄ B magnetic powder is filled in a mold, and a test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm is used for measuring magnetic properties at a pressure of 16 t / cm ² . A compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared.

(2) The compression-molded test piece prepared in (1) above is placed in the bat so that the pressing direction is horizontal, and the SiO ₂ precursor solution as the binder is placed vertically in the bat. Injection was performed so as to be 1 mm / min in the direction. The SiO ₂ precursor solution was poured into the vat until it was finally 5 mm above the upper surface of the compression molded specimen.

(3) The compression molding test piece used in the above (2) was arranged, and a bat filled with the SiO ₂ precursor solution was set in a vacuum vessel and gradually exhausted to about 80 Pa. The sample was left until the generation of bubbles from the surface of the compression molded test piece was reduced.

(4) The compression molded test piece was placed, the internal pressure of the vacuum vessel in which the bat filled with the SiO ₂ precursor solution was set was gradually returned to atmospheric pressure, and the compression molded test piece was taken out from the SiO ₂ precursor solution. .

(5) The compression molding test piece impregnated with the SiO ₂ precursor solution prepared in the above (4) is set in a vacuum drying furnace, and the compression molding test piece is subjected to a pressure of 1 to 3 Pa at 150 ° C. Vacuum heat treatment was applied.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm produced in the above (5).

  (7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was performed using the compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm prepared in (5) above. For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

The bending strength of the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (7) above is ₂ MPa or less before the SiO ₂ impregnation, but the magnet forming has a bending strength of 190 MPa after the SiO ₂ impregnation heat treatment. It was possible to make a body.

Regarding the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (5) above, the residual magnetic flux density can be improved by 20% compared to the resin-containing bond magnet (Comparative Example 1). There the demagnetization curve measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. However, the thermal demagnetization rate after 1 hour of holding at 200 ° C. in the atmosphere was 3.6% in this comparative example, which was a large value compared with 3.0% in the SiO ₂ impregnated bonded magnet in the example. Furthermore, the irreversible thermal demagnetization rate after returning to room temperature after 1 hour at 200 ° C. and re-magnetization is less than 1% when the SiO ₂ impregnation treatment is performed in the example, whereas 1.6% in this comparative example. It became the value of. This was found to be due to the fact that the SiO ₂ precursor solution penetrated into the magnet only up to about 2 mm from the magnet surface. Therefore, the magnetic powder in the central part of the magnet causes oxidative deterioration during heating in the atmosphere, which is the reason why the magnet of this comparative example has a larger irreversible heat demagnetization rate than the magnet of the example.

From this result, although the bonded magnet of this comparative example is not inferior to the conventional epoxy-based bonded magnet, the long-term reliability may be lower than that of the conventional epoxy-based bonded magnet. It is desirable to use it in consideration of this point.
(Comparative Example 5)
In this comparative example, magnetic powder obtained by pulverizing an NdFeB-based ribbon similar to [Example 1] was used for the rare earth magnet magnetic powder. A treatment liquid for forming a rare earth fluoride or alkaline earth metal fluoride coat film was prepared as follows.

  (1) A salt having high solubility in water, for example, in the case of Nd, Nd acetate Nd or 4 g of nitrate Nd was introduced into 100 ml of water, and completely dissolved using a shaker or an ultrasonic stirrer.

(2) Hydrofluoric acid diluted to 10% was gradually added in an amount equivalent to the chemical reaction for producing NdF ₃ .

(3) The solution in which the gel-like precipitate NdF ₃ was produced was stirred for 1 hour or more using an ultrasonic stirrer.

  (4) After centrifugation at 4000 to 6000 rpm, the supernatant was removed and approximately the same amount of methanol was added.

(5) A methanol solution containing gel-like NdF ₃ was stirred to form a complete suspension, and then stirred for 1 hour or more using an ultrasonic stirrer.

  (6) The above operations (4) and (5) were repeated 3 to 10 times until no anion such as acetate ion or nitrate ion was detected.

(7) Finally, in the case of NdF ₃ , an almost transparent sol-like NdF ₃ was obtained. A methanol solution containing 1 g / 5 ml of NdF ₃ was used as the treatment liquid.

The process of forming the rare earth fluoride or alkaline earth metal fluoride coat film on the magnetic powder of Nd ₂ Fe ₁₄ B was carried out by the following method.

In the case of NdF ₃ coat film formation process: NdF ₃ concentration 1 g / 10 ml translucent sol solution (1) Add 15 ml of NdF ₃ coat film forming treatment liquid to 100 g of magnetic powder obtained by pulverizing NdFeB thin ribbon, The mixing was performed until it was confirmed that the entire magnetic powder for rare earth magnet was wet.

(2) Methanol removal of the solvent was performed on the magnetic powder for rare earth magnets subjected to the NdF ₃ coat film forming treatment of (1) above under a reduced pressure of 2 to 5 torr.

(3) The rare earth magnet magnetic powder from which the solvent of (2) has been removed is transferred to a quartz boat and heat-treated at 200 ° C. for 30 minutes and 400 ° C. for 30 minutes under a reduced pressure of 1 × 10 ⁻⁵ torr. It was.

(4) After the magnetic powder heat-treated in (3) above is transferred to a lid made by Macor (manufactured by Riken Denshi), heat treatment is performed at 700 ° C. for 30 minutes under a reduced pressure of 1 × 10 ⁻⁵ torr. went.

(5) Nd ₂ Fe ₁₄ B magnetic powder coated with the rare earth fluoride or alkaline earth metal fluoride coating film is filled in a mold, and is 10 mm in length and 16 mm in width for measuring magnetic properties at a pressure of 16 t / cm ^2. 10
A test piece having a thickness of 5 mm and a thickness of 5 mm was prepared, and a compression test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared for strength measurement.

  (6) The specific resistance was measured by the four-probe method for the compression molded test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm produced in the above (5).

  (7) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (8) A mechanical bending test was performed using the compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm prepared in (5) above. For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

Regarding the magnetic properties of the compression molded test piece of 10mm length, 10mm width and 5mm thickness produced in (5) above, the residual magnetic flux density can be improved by about 20% compared to the resin-containing bond magnet (Comparative Example 1). , and the demagnetization curve was measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. Further, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere was 3.0% in this comparative example, which was equivalent to 3.0% in the SiO ₂ impregnated bonded magnet in the example. Further, the irreversible thermal demagnetization rate after returning to room temperature after 1 hour at 200 ° C. and re-magnetization is less than 1% when the SiO ₂ impregnation treatment is performed in the example, whereas in this comparative example, it is less than 1%. Value. The results are shown in Table 7.

However, the bending strength of the compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm produced in (7) is 2.9 MPa because it is not impregnated with SiO _{2 in} this comparative example. The value was about 1/15 compared to the bond magnet.

From this result, the bonded magnet of this comparative example has poor mechanical strength compared to the conventional epoxy-based bonded magnet, and attention should be paid to this point in use.
(Comparative Example 6)
In this example, magnetic powder obtained by pulverizing a NdFeB-based ribbon similar to [Example 1] was used for the rare earth magnet magnetic powder. Moreover, the process liquid which forms a phosphate chemical conversion treatment film was produced as follows.

  20 g of phosphoric acid, 4 g of boric acid and 4 g of MgO as a metal oxide were dissolved in 1 liter of water, and EF-104 (manufactured by Tochem Products) as a surfactant was added to 0.1 wt%. As a rust preventive agent, benzotriazole (BT) was added to 0.04 mol / l.

The process of forming the phosphate chemical conversion film on the magnetic powder of Nd ₂ Fe ₁₄ B was carried out by the following method. Table 4 shows the composition of the phosphating solution used.

  (1) 5 ml of a phosphating solution was added to 100 g of magnetic powder obtained by pulverizing a NdFeB-based ribbon, and mixed until it was confirmed that the entire magnetic powder for rare earth magnets was wetted.

(2) The rare earth magnet magnetic powder subjected to the phosphatization film forming process of (1) above is heated at 180 ° C.
Heat treatment was performed for 30 minutes under a reduced pressure of 2 to 5 torr.

(3) A magnetic powder of Nd ₂ Fe ₁₄ B subjected to the above-mentioned phosphatization film formation treatment is filled in a mold, and is 10 mm long, 10 mm wide and 5 mm thick for measuring magnetic properties at a pressure of 16 t / cm ^2. In addition, a compression molded test piece having a length of 15 mm, a width of 10 mm, and a thickness of 2 mm was prepared for strength measurement.

  (4) The specific resistance was measured by the four-probe method on the compression molded test piece having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm produced in the above (3).

(5) Further, a pulse magnetic field of 30 kOe or more was applied to the compression molded test piece whose specific resistance was examined. The compression molded specimen was examined for magnetic properties.

  (6) A mechanical bending test was carried out using the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in (3) above. For the bending test, a compression molded body having a sample shape of 15 mm × 10 mm × 2 mm was used, and the bending strength was evaluated by a three-point bending test with a distance between supporting points of 12 mm.

Regarding the magnetic properties of the compression molded test piece of 10 mm length, 10 mm width and 5 mm thickness produced in (3), the residual magnetic flux density can be improved by about 25% compared to the resin-containing bond magnet (Comparative Example 1). There the demagnetization curve measured at 20 ° C., the value of residual magnetic flux density and coercivity and SiO ₂ before impregnated with the molded body after SiO ₂ infiltration and heating were almost the same. In addition, the thermal demagnetization factor after 1 hour of holding at 200 ° C. in the atmosphere was 3.1% in this comparative example, which was substantially equivalent to 3.0% in the SiO ₂ impregnated bonded magnet in the example. Further, the irreversible thermal demagnetization rate after returning to room temperature after 1 hour at 200 ° C. and re-magnetization is less than 1% when the SiO ₂ impregnation treatment is performed in the example, whereas in this comparative example, it is 1.2%. Although there was a slight increase in the value, there was no significant difference (Table 7). However, with respect to the bending strength of the compression molded test piece of 15 mm length, 10 mm width and 2 mm thickness produced in the above (5), since it was not impregnated with SiO _{2 in} this comparative example, a value of 2.9 MPa was obtained. The value was about 1/20 compared with the system bond magnet.

  From this result, the bonded magnet of this comparative example has poor mechanical strength compared to the conventional epoxy-based bonded magnet, and it is necessary to use this point with sufficient consideration in use.

  Although the present invention has been described with reference to the above-described embodiments, the magnet of the present invention has the following effects.

  1) Performance as a magnet is superior to conventional resin magnets.

  2) In addition to superior properties, it also has a strong strength as a magnet. It is possible to obtain a magnet that has excellent characteristics and strength that could not be obtained with a resin magnet.

  The effects 1) and 2) are achieved as described above, for example, as follows.

  It is necessary to infiltrate the binder solution into the gap between the magnetic powder of 1 μm or less and the magnetic powder, which is generated when the magnetic powder is compression molded without a resin. For this purpose, the viscosity of the binder solution must be 100 mPa · s or less, and the wettability of the magnetic powder and the binder solution must be high. Furthermore, it is important that the adhesive between the binder after curing and the magnetic powder is high, the mechanical strength of the binder is large, and the binder is continuously formed.

The viscosity of the binder solution depends on the size of the magnet, but when the thickness of the compression molded body is 5 mm or less and the gap between the magnetic powder and the magnetic powder is about 1 μm, the viscosity of the binder solution is about 100 mPa · s. It is possible to introduce the binder solution into the gap between the magnetic powders up to the center of the compression molded body. When the thickness of the compression molded body is 5 mm or more and the gap between the magnetic powder and the magnetic powder is about 1 μm, for example, in the compression molded body having a thickness of about 30 mm, the binder solution is introduced to the center of the compression molded body When the viscosity of the binder solution is about 100 mPa · s, the viscosity of the binder solution is 20 mPa · s or less, preferably 10 mPa · s or less. This is a viscosity that is one digit or more lower than that of a normal resin. For that purpose, it is necessary to control the hydrolysis amount of the alkoxy group in the alkoxysiloxane which is the precursor of SiO ₂ and to suppress the molecular weight of the alkoxysiloxane. That is, when an alkoxy group is hydrolyzed, a silanol group is generated. The silanol group easily undergoes a dehydration condensation reaction, and the dehydration condensation reaction means an increase in the molecular weight of the alkoxysiloxane. Further, since silanol groups generate hydrogen bonds with each other, the viscosity of the alkoxysiloxane solution that is the precursor of SiO ₂ increases. Specifically, the amount of water added to the hydrolysis reaction equivalent of alkoxysiloxane and the hydrolysis reaction conditions are controlled. As the solvent used for the binder solution, it is desirable to use alcohol because the alkoxy group in alkoxysiloxane has a fast dissociation reaction. As the solvent alcohol, methanol, ethanol, n-propanol, and iso-propanol having a lower boiling point than water and a low viscosity are preferable, but the viscosity of the binder solution does not increase in several hours and the boiling point is lower than that of water. If it is, it can be used for manufacture of the magnet according to the present invention.

For the adhesion between the binder and the magnetic powder after curing, SiO ₂ precursor, which is binding agent is used in the present invention because the product after the heat treatment is SiO _2, the surface of the magnetic powder in the natural oxide film If covered, the adhesion between the surface of the magnetic powder and SiO ₂ is large, and rare earth magnets using SiO ₂ as the binder have a cohesive fracture surface of the magnetic powder or SiO ₂ when the magnet is broken. On the other hand, when a resin is used as the binder, the adhesion between the resin and the magnetic powder is generally smaller than that of the magnetic powder surface and SiO ₂ . Therefore, in a bonded magnet using a resin, the surface when the magnet is broken has both an interface between the resin and magnetic powder or a cohesive failure surface of the resin. Therefore, in order to improve the magnet strength, it is more advantageous to use SiO ₂ as the binder than to use the resin as the binder.

When the content of rare earth magnetic powder in the magnet is 75 vol% or more, a compression molded type rare earth magnet is used, but the strength of the rare earth magnet after curing the binder is that of the binder after curing. Whether or not a continuum is generated has a great influence. This is because the breaking strength of the binder alone having the same area is larger than the breaking strength of the adhesive interface. When resin such as epoxy resin is used, if the resin volume fraction in the total solid content is 15 vol% or less, it cannot be said that the wettability between the resin and the rare earth magnetic powder is good. Does not become a continuum but is distributed in islands. On the other hand, as described above, the SiO ₂ precursor has good wettability with the rare earth magnetic powder. Therefore, the SiO ₂ precursor spreads continuously on the surface of the magnetic powder, and is cured by heat treatment in the continuously spread state. It becomes SiO ₂ . On the other hand, when the strength of the binder after curing is expressed in terms of bending strength, SiO ₂ is 1 to 3 orders of magnitude larger than that of the resin system. Therefore, the strength of the rare earth magnet after the binder is cured is much higher when the SiO ₂ precursor is used as the binder than when the resin is used.

Next, magnet materials more suitable for the magnet according to the present invention will be described. Rare earth magnet powder consists of a ferromagnetic main phase and other components. When the rare earth magnet is an Nd—Fe—B based magnet, the main phase is an Nd ₂ Fe ₁₄ B phase. Considering improvement in magnet characteristics, the rare earth magnet powder is preferably a magnet powder prepared by using the HDDR method or hot plastic working. Examples of the rare earth magnet powder include Sm—Co magnets in addition to Nd—Fe—B magnets. Considering the magnet characteristics of the obtained rare earth magnet and the manufacturing cost, Nd—Fe—B type magnets are preferable. However, the rare earth magnet of the present invention is not limited to Nd—Fe—B magnets. In some cases, two or more rare earth magnet powders may be mixed in the rare earth magnet. That is, two or more types of Nd—Fe—B magnets having different composition ratios may be included, and Nd—Fe—B magnets and Sm—Co magnets may be mixed.

  In the present specification, the “Nd—Fe—B magnet” is a concept including a form in which a part of Nd or Fe is substituted with another element. Nd may be substituted with other rare earth elements such as Dy and Tb. Only one of these may be used for substitution, or both may be used. The substitution can be performed by adjusting the blending amount of the raw material alloy. By such replacement, the coercive force of the Nd—Fe—B magnet can be improved. The amount of Nd to be substituted is preferably 0.01 atom% or more and 50 atom% or less with respect to Nd. If it is less than 0.01 atom%, the effect of substitution may be insufficient. If it exceeds 50 atom%, the residual magnetic flux density may not be maintained at a high level, and it is desirable to pay attention to the application in which the magnet is used.

  On the other hand, Fe may be substituted with other transition metals such as Co. By such substitution, the Curie temperature (Tc) of the Nd—Fe—B magnet can be increased and the operating temperature range can be expanded. The amount of Fe to be substituted is preferably 0.01 atom% or more and 30 atom% or less with respect to Fe. If it is less than 0.01 atom%, the effect of substitution may be insufficient. If it exceeds 30 atom%, the coercive force may decrease significantly, and it is desirable to pay attention to the application in which the magnet is used.

  The average particle diameter of the rare earth magnet powder in the rare earth magnet is preferably 1 to 500 μm. When the average particle size of the rare earth magnet powder is less than 1 μm, the specific surface area of the magnetic powder is large and the influence of oxidative degradation is great, and there is a concern that the magnet characteristics of a rare earth magnet using the rare earth magnet powder may be deteriorated. Therefore, in this case, it is desirable to pay attention to the usage state of the magnet.

On the other hand, if the average particle size of the rare earth magnet powder is larger than 500 μm, the magnet powder is crushed by the pressure at the time of manufacture, and it becomes difficult to obtain sufficient electric resistance. In addition, when an anisotropic magnet is manufactured using anisotropic rare earth magnet powder as a raw material, the main phase in rare earth magnet powder (Nd ₂ Fe _{14 in} Nd—Fe—B magnets) extends over a size exceeding 500 μm. It is difficult to align the orientation direction of the (B phase). The particle size of the rare earth magnet powder is controlled by adjusting the particle size of the rare earth magnet powder that is the raw material of the magnet. The average particle size of the rare earth magnet powder can be calculated from the SEM image.

  The present invention relates to an isotropic magnet manufactured from isotropic magnet powder, an isotropic magnet in which anisotropic magnet powder is randomly oriented, and an anisotropic magnet in which anisotropic magnet powder is oriented in a certain direction. Any of them can be applied. If a magnet having a high energy product is required, an anisotropic magnet using anisotropic magnet powder as a raw material and oriented in a magnetic field is suitable.

The rare earth magnet powder is produced by blending raw materials according to the composition of the rare earth magnet to be produced. When producing an Nd—Fe—B based magnet whose main phase is the Nd ₂ Fe ₁₄ B phase, a predetermined amount of Nd, Fe, and B is blended. As the rare earth magnet powder, one produced by a known method may be used, or a commercially available product may be used. Such rare earth magnet powder is an aggregate of a large number of crystal grains. The crystal grains constituting the rare earth magnet powder are suitable for improving the coercive force when the average particle diameter is not more than the single domain critical particle diameter. Specifically, the average grain size of the crystal grains is preferably 500 nm or less. In the HDDR method, the Nd—Fe—B alloy is hydrogenated to decompose the Nd ₂ Fe ₁₄ B compound as the main phase into three phases of NdH ₃ , α-Fe, and Fe ₂ B, Thereafter, Nd ₂ Fe ₁₄ B is again generated by forced dehydrogenation. The UPSET method is a technique in which an Nd—Fe—B alloy produced by an ultra-quenching method is subjected to plastic working hot after pulverization and temporary molding.

  As a use application of the magnet, an inorganic insulating film is preferably formed on the surface of the rare earth magnet powder under a condition where a high frequency magnetic field including harmonics is applied to the magnet. Thereby, the electrical resistance inside a magnet can be enlarged, an eddy current can be reduced, and the eddy current loss in a magnet can be reduced. As such an inorganic insulating film, a film formed by using a phosphating solution containing phosphoric acid, boric acid, and magnesium ions is preferable. In order to ensure the uniformity of the film thickness and the magnetic properties of the magnetic powder, the surface activity is required. It is desirable to use an agent and a rust inhibitor in combination. In particular, it is desirable that the surfactant is a perfluoroalkyl surfactant and the rust inhibitor is a benzotriazole rust inhibitor.

Furthermore, a fluoride coat film is desirable as the inorganic insulating film for the purpose of improving the insulating properties and magnetic characteristics of the magnetic powder. As the treatment liquid for forming the fluoride coat film, rare earth fluoride or alkaline earth metal fluoride is swollen in a solvent mainly composed of alcohol, and the rare earth fluoride or alkaline earth metal fluoride is used. Is preferably a solution in a sol state in which the average particle size is pulverized to 10 μm or less and dispersed in a solvent containing alcohol as a main component. In order to improve the magnetic properties, it is desirable to heat-treat the magnetic powder having the fluoride coat film formed on the surface in an atmosphere of 1 × 10 ⁻⁴ Pa or less and at a temperature of 600 to 700 ° C.
<Effect of self-starting permanent magnet synchronous motor with the above structure>
The magnets used in the first and second self-starting permanent magnet synchronous motors 24 shown in FIG. 1 have the structure described above, that is, a powder magnetic material and a binder precursor with good wettability. Is produced by impregnating a magnet with at least one or more of the following effects. As described above, SiO ₂ is most suitable as a binder for the powder magnetic material and the precursor having good wettability.

  Effect 1 In the above-described magnet manufacturing process, there is no sintering process heated to a high temperature, so that the magnet can be manufactured easily.

  Since it is not a magnet using an epoxy resin, which is referred to as an effect 2, and commonly referred to as a bond magnet, the magnetic characteristics of the magnet are superior to those of a bond magnet, and a self-starting permanent magnet synchronous motor having relatively good characteristics at low cost is obtained. be able to.

  Effect 3, after the magnet is molded with the magnet material, the binder can be cured at a relatively low temperature, and the shape and size of the molded magnet material are less changed. Since it can be manufactured with high accuracy with respect to the shape and dimensions of the magnet, high characteristics can be obtained as a motor or a generator. That is, the cutting work after fixing the magnet material with the binder is very little and easy. For example, it is not a substantial magnet-shaped forming process, such as cutting the protruding portion of the adhesive, so that the process is easy. Since the conventional sintered magnet is heated to a high temperature for sintering, it shrinks in the process of lowering the temperature thereafter, and the shape of the magnet material changes. Therefore, in the conventional sintered magnet, it has been necessary to spend a lot of time for cutting for adjusting the shape and dimensions of the magnet after the sintering process. In the above-described embodiment, a necessary magnet shape can be obtained with extremely few cutting processes and, in some cases, without a cutting process.

  Effect 4, as described above, since the molding shape of the magnet material hardly changes in the subsequent binder impregnation or curing process, the magnet is manufactured while maintaining the curved shape of the magnet material by pressing or the like with high accuracy. It is possible. Theoretically, a permanent magnet synchronous motor with good characteristics that can realize the curved shape of a magnet that was difficult to commercialize because there is no method that can be mass-produced even if the thickness and shape of the preferred magnet are known in theory. It is possible to obtain

Effect 5, sintered rare earth magnets have low electrical resistance and large loss and heat generation due to eddy currents. The magnet can form an insulating film on the surface of the powder magnet, and the eddy current loss and heat generation of the magnet can be greatly reduced. Self-starting permanent magnet synchronous motors, especially self-starting permanent magnet synchronous motors used in compressors, can be used in an environment exceeding 100 degrees and can suppress heat generation due to eddy currents in the magnet to a low level. is necessary. In the above-described embodiment, since the electric resistance can be increased, the heat generation of the magnet can be reduced. Further, the loss of the self-starting permanent magnet synchronous motor can be reduced correspondingly, and the efficiency is improved.
<Other Embodiments of Self-Starting Permanent Magnet Synchronous Motor>
FIG. 9 is a radial sectional view of a rotor of a synchronous motor according to another embodiment of the present invention. In FIG. 9, the same components as those in FIG. The difference from FIG. 2 is that the radius (hereinafter simply referred to as the outer diameter) r3 of the arc that forms the outer periphery of the permanent magnet 4 is shorter than the outer diameter r1 of the magnet insertion hole 7 and is non-concentric. That is, the outer diameter r1 of the magnet insertion hole 7 is an arc having a radius r1 with the origin O of the shaft 6 as the center. On the other hand, the outer diameter r3 of the permanent magnet 4 is an arc having a radius r3 centered on a point O1 that is shifted from the origin O by a distance l. Here, the inner diameter of the permanent magnet 4 is the same as the inner diameter r4 of the magnet insertion hole 7.

  If an eccentric magnet that can be manufactured by applying the present invention is used as in this embodiment, the gap length of the circumferential end of the magnet is widened, so that the magnetic flux near the end is chained to the stator winding. Intersection can be reduced and it can be made closer to a sine wave.

  Therefore, according to this embodiment, the same effect as in FIG. 2 can be obtained, and the magnetic flux distribution can be made closer to a sine wave.

1 is a radial cross-sectional view of a self-starting permanent magnet synchronous motor according to an embodiment of the present invention. 1 is a radial sectional view of a rotor of a self-starting permanent magnet synchronous motor according to an embodiment of the present invention. The graph which shows the measured data of motor efficiency and induced electromotive force waveform distortion. The figure explaining the manufacturing process of a magnet assembly. Another embodiment of the manufacturing process of a magnet assembly. Still another embodiment of the manufacturing process of the magnet assembly. Sectional drawing of the manufactured magnet. The figure which shows the experimental result of a magnet. 3 shows another embodiment of the rotor shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotor 2 Rotor core 3 Cage type | mold winding 4 Permanent magnet 5 Hole 6 Shaft 7 Magnet insertion hole 8 Stator 9 Stator core 10 Slot 11 Teeth 12 Armature winding 24 Self-starting permanent magnet synchronous motor

Claims (24)

A stator having a stator core and a stator winding;
Having a rotor rotatably arranged through a gap between the stator and
The rotor includes a rotor core, a number of slots provided in the circumferential direction in the vicinity of the outer periphery of the rotor core, a conductive bar embedded in the slots, and a short circuit between the bars at the end face in the axial direction. Conductive end ring,
A plurality of permanent magnets embedded in a magnet insertion hole arranged on the inner peripheral side of the bar,
The permanent magnet comprises a field pole, and the permanent magnet is composed of a magnetic powder and a binder having SiO ₂ that binds the magnetic powder. Electric motor. In claim 1,
A self-starting permanent magnet synchronous motor characterized in that a ratio θ / α between a circumferential pitch angle θ of the permanent magnet and a magnetic pole pitch angle α is 0.54 or more and 0.91 or less. In claim 1,
The permanent magnet synchronous motor according to claim 1, wherein the permanent magnets are magnetized so that polarities of the permanent magnets arranged on both sides in the circumferential direction are opposite to each other. In claim 1,
The permanent magnet synchronous motor according to claim 1, wherein the permanent magnet has a substantially arc shape from the center of the field pole. In claim 1,
A self-starting permanent magnet synchronous motor, wherein at least one hole is provided between adjacent magnetic poles of the rotor.   2. The self-starting permanent magnet synchronous motor according to claim 1, wherein the binder contains an alkoxy group. In claim 1,
A self-starting permanent magnet synchronous motor, wherein the magnetic powder has an inorganic insulating film having a thickness of 10 μm to 10 nm on the surface. In claim 1,
The binder contains at least one of alkoxysiloxane, alkoxysilane, a product of hydrolysis thereof, and a dehydration condensate thereof, which is a precursor of SiO ₂ , and water. Permanent magnet synchronous motor. In claim 1,
The binder contains at least one of alkoxy siloxane, alkoxy silane, a hydrolysis product thereof, a hydrolysis product thereof, and a dehydration condensation product thereof, which is a precursor of SiO ₂ , and water, and further contains an alcohol and a catalyst for hydrolysis. Includes self-starting permanent magnet synchronous motor. In claim 1,
The permanent magnet, compression molding the rare earth magnetic powder, the rare earth magnetic powder formed by compression molding is impregnated with a SiO ₂ precursor was molded by binding a rare earth magnetic powder with SiO ₂ A self-starting permanent magnet synchronous motor characterized by that. In claim 10,
The self-starting permanent magnet synchronous motor, wherein the binder contains a neutral catalyst as a catalyst for hydrolysis. In claim 11,
A self-starting permanent magnet synchronous motor, wherein the neutral catalyst is a tin catalyst. In claim 8,
A self-starting permanent magnet synchronous motor characterized in that a total volume fraction of the alkoxysiloxane, alkoxysilane, hydrolysis product thereof, and dehydration condensate thereof is 5 vol% or more and 96 vol% or less. In claim 8,
The amount of water in the binder is equivalent to the hydrolysis reaction equivalent to the total amount of alkoxysiloxane, alkoxysilane, the product of hydrolysis thereof, and the alkoxysiloxane and alkoxysilane which are precursors of the dehydration condensate. A self-starting permanent magnet synchronous motor characterized by being 1/10 to 1. In claim 7,
The self-starting permanent magnet synchronous motor, wherein the inorganic insulating film is formed of a rare earth fluoride or alkaline earth metal fluoride coating film or a phosphate chemical conversion film. In claim 15,
The coating film of rare earth fluoride or alkaline earth metal fluoride is Mg, Ca, Sr, Ba, La, Ce, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu fluoride. A self-starting permanent magnet synchronous motor comprising at least one of them. In claim 15,
The coating film of rare earth fluoride or alkaline earth metal fluoride has the rare earth fluoride or alkaline earth metal fluoride swollen in a solvent mainly composed of alcohol, and the rare earth fluoride or alkaline earth fluoride in a sol state. A self-starting permanent magnet synchronous motor, characterized in that it is formed by using a treatment liquid in which the average particle size of a metal fluoride is pulverized to 10 μm or less and mixed with a solvent mainly composed of alcohol. In claim 17,
A self-starting permanent magnet synchronous motor, wherein the alcohol is methyl alcohol, ethyl alcohol, n-propyl alcohol or isopropyl alcohol.   The phosphate chemical conversion film according to claim 15 contains phosphoric acid, boric acid, and one or more of Mg, Zn, Mn, Cd, Ca, Sr, and Ba. Type permanent magnet synchronous motor.   The phosphate chemical conversion treatment film according to claim 15 is formed of an aqueous solution containing one or more of phosphoric acid, boric acid, Mg, Zn, Mn, Cd, Ca, Sr, and Ba. A self-starting permanent magnet synchronous motor. The phosphate chemical conversion treatment film according to claim 15 contains one or more of phosphoric acid, boric acid, Mg, Zn, Mn, Cd, Ca, Sr, and Ba, and a surfactant and a rust inhibitor. Formed from an aqueous solution containing
Self-starting permanent magnet synchronous motor.   The self-starting permanent magnet synchronous motor according to claim 21, wherein the surfactant is a perfluoroalkyl-based, alkylbenzenesulfonic acid-based, zwitterionic-based, or polyether-based surfactant.   The self-starting permanent magnet synchronous motor according to claim 21, wherein the rust preventive agent is an organic compound containing at least one of nitrogen and sulfur having an isolated couple. The organic compound rust preventive agent containing at least one of nitrogen and sulfur having an isolated couple according to claim 23 is represented by chemical formula 1

(Wherein X is any one of H, CH ₃ , C ₂ H ₅ , C ₃ H ₇ , NH ₂ , OH, and COOH). Starter type permanent magnet synchronous motor.

Images