WO2000016347A1 - Corrosion-resistant permanent magnet and method for producing the same - Google Patents

Abstract

A permanent magnet, characterized in that it is a Fe-B-R permanent magnet which has, on the surface thereof and with an intervening aluminum film, a chemically formed film comprising at least one selected from between zirconium and titanium, phosphorus, oxygen and fluorine as constituent elements; and a method for producing the same. The permanent magnet has excellent corrosion resistance due to the chemically formed film closely adhered to the surface of the magnet via the aluminum film and thus, even after the magnet is allowed to stand under a high temperature and high humidity condition of 80 °C (temperature) x 90 % (relative humidity) for a long period of time, it maintains its original magnetic characteristics with no deterioration and exhibits stable and excellent magnetic characteristics. The magnet also has an advantage that it contains no hexavalent chromium in the film.

Description

TECHNICAL FIELD The present invention relates to a corrosion-resistant permanent magnet and a method for manufacturing the same.

 The present invention relates to a Fe—B—R-based permanent magnet having an excellent corrosion-resistant film and a method for producing the same. More specifically, it has excellent adhesion to magnets and stable magnetic properties without deterioration in magnetic properties even when left for a long time under high temperature and humidity conditions of 80 ° C and 90% relative humidity. The present invention relates to a Fe—BR—R permanent magnet having a corrosion-resistant coating on the magnet surface that does not contain hexavalent chromium in the coating and a method for producing the same. Background art

 Fe-B-R permanent magnets typified by Fe-B-Nd permanent magnets use resources that are more abundant and inexpensive than Sm-Co permanent magnets, and Because of its high magnetic properties, it has been put to practical use in various applications.

 However, since Fe-B-R permanent magnets contain highly reactive R and Fe, they are susceptible to oxidative corrosion in the air, and if used without any surface treatment, they will be slightly Corrosion progresses from the surface due to the presence of kana acid or moisture, and water is generated, resulting in deterioration and variation in magnet properties. Furthermore, if the magnets generated by 鲭 are incorporated into a device such as a magnetic circuit, the mackerel may scatter and contaminate peripheral components.

In view of the above, in order to improve the corrosion resistance of Fe-B-R permanent magnets, the magnet surface has corrosion resistance by a wet plating method such as electroless plating, electric plating, and plating. A magnet formed with a metal plating film has already been proposed (see Japanese Patent Publication No. 3-74012). However, in this method, the acidic solution or the alkaline solution used in the pretreatment of the plating treatment remains in the magnet hole, and the magnet may corrode with time. Further, since the magnet has poor chemical resistance, the surface of the magnet may be corroded during plating. Furthermore, as described above, a metal plating film is formed on the magnet surface However, when a corrosion resistance test is performed under the conditions of a temperature of 60 ° C and a relative humidity of 90%, the magnetic properties may be degraded by more than 10% from the initial value after 100 hours.

 In addition, a method of forming an oxidation-resistant chemical conversion film such as a phosphate film or a chromate film on the surface of a Fe—B—R permanent magnet has been proposed (Japanese Patent Publication No. 4-22008). Although the coating obtained by this method is excellent in terms of adhesion to magnets, the corrosion resistance test at a temperature of 60 ° C and a relative humidity of 90% shows that after 300 hours, Its magnetic properties may degrade by more than 10% from its initial value.

 In addition, a method proposed to improve the corrosion resistance of Fe—B—R permanent magnets is to form an aluminum film by vapor phase growth and then to treat it with chromate, a so-called aluminum mate treatment. (Refer to Japanese Patent Publication No. 6-66 1773) significantly improves the corrosion resistance of magnets. However, the chromate treatment used in this method uses hexavalent chromium, which is environmentally undesirable, so that the waste liquid treatment method is complicated. In addition, since the film obtained by this method contains a small amount of hexavalent chromium, there is a concern that it may affect the human body when handling the magnet.

 Therefore, in the present invention, the magnetic properties are not deteriorated even when left for a long time under a high temperature and high humidity condition of 80 ° C. and 90% relative humidity, and the magnetic properties are stable and high. An object of the present invention is to provide a Fe—B—R-based permanent magnet that can exhibit magnetic properties and that has a corrosion-resistant coating on the magnet surface that does not contain hexavalent chromium in the coating and a method for producing the same. Disclosure of the invention

 The present inventors conducted various studies in view of the above points, and as a result, formed an aluminum film on the surface of the Fe—B—R permanent magnet, and further formed titanium and nickel as constituent elements on the aluminum film. Alternatively, it has been found that when a chemical conversion film containing zirconium is formed, the chemical conversion film firmly adheres to the magnet via the aluminum film, and exhibits excellent corrosion resistance.

The present invention has been made based on this finding. As described in claim 1, the permanent magnet of the present invention has a structure in which an Fe—B—R-based permanent magnet is formed on the surface of the permanent magnet via an aluminum film. At least one element selected from titanium and zirconium as an element, It has a chemical conversion film containing phosphorus, oxygen and fluorine.

 The permanent magnet according to claim 2 is characterized in that, in the permanent magnet according to claim 1, the aluminum film has a thickness of 0.01 m to 50 m.

A permanent magnet according to claim 3 is characterized in that, in the permanent magnet according to claim 1, the chemical conversion film has a thickness of 0.01 ^ m-1. Further, the permanent magnet according to claim 4 is the permanent magnet according to claim 1, wherein the content of titanium and / or zirconium in the chemical conversion film is equal to a film formed on the magnet surface lm ^2. 0.1 mg to 100 mg.

The permanent magnet according Claim 5, the Ri in the permanent magnet in the range first claim of claim, per film content of phosphorus in the chemical conversion film is formed on the magnet surface lm ² 0. lmg to l0 Omg.

The permanent magnet according to claim 6 is the permanent magnet according to claim 1, wherein the oxygen content in the chemical conversion coating is 0% per film formed on the magnet surface 1 m ^2. 2 mg to 30 Omg.

The permanent magnet according Claim 7, in the permanent magnet in the range first claim of claim, or film Oh content of fluorine in the chemical conversion film is formed on the magnet surface 1 m ² 0. It is characterized by being in the range of 05 mg to 10 Omg.

 The permanent magnet according to claim 8 is the permanent magnet according to claim 1, wherein the ratio of the number of moles of phosphorus to the number of moles of titanium and Z or zirconium in the vicinity of the surface of the chemical conversion film is formed. It is characterized by being larger than the ratio in the whole film.

The permanent magnet according to claim 9 is the permanent magnet according to claim 1, wherein the ratio of the number of moles of phosphorus to the number of moles of titanium and Z or zirconium in the vicinity of the surface of the chemical conversion film is 1%. It is characterized by the above. Further, the method for producing a permanent magnet according to the present invention includes, as described in claim 10, after forming an aluminum film on the surface of the Fe-B-R permanent magnet, forming a titanium compound on the aluminum film. At least one selected from zirconium compounds A treatment liquid containing at least one selected from a seed, phosphoric acid, condensed phosphoric acid, phytic acid, a hydrolyzate of phytic acid and a salt thereof and a fluorine compound is applied, and dried to obtain titanium as a constituent element. And a chemical conversion film containing at least one selected from zirconium and phosphorus, oxygen and fluorine.

 A manufacturing method according to claim 11 is characterized in that, in the manufacturing method according to claim 10, the aluminum film is formed by a vapor phase growth method.

 Further, the manufacturing method according to claim 12 is the manufacturing method according to claim 11, wherein an aluminum film having a thickness of 0.01 zm to 50 x rn is formed. Features.

 The manufacturing method according to claim 13, wherein, in the manufacturing method according to claim 10, the Fe—B—R-based permanent magnet and the aluminum piece are placed in a processing container, and the processing container It is characterized in that an aluminum film is formed by applying vibration to both of them and agitating Z or both.

 Further, a manufacturing method according to claim 14 is characterized in that, in the manufacturing method according to claim 13, an aluminum film having a thickness of 0.01 x m-1 is formed.

 Further, the production method according to claim 15 is the production method according to claim 10, wherein at least one kind of mole number (in terms of metal) selected from a titanium compound and a zirconium compound in the treatment liquid is contained. ), The ratio of at least one mole (in terms of phosphorus) of at least one selected from a phosphoric acid, a condensed phosphoric acid, a phytic acid, a phytic acid hydrolyzate and a salt thereof is 1 or more. BEST MODE FOR CARRYING OUT THE INVENTION

 The permanent magnet of the present invention comprises, on an Fe—B—R permanent magnet surface, a conversion coating containing at least one selected from titanium and zirconium as a constituent element, phosphorus, oxygen and fluorine, via an aluminum coating. It is characterized by having.

The method for forming an aluminum film on the surface of F e— B— R permanent magnets is particularly limited It is not something to be done. However, considering that the magnet and the aluminum film are easily oxidized and corroded, the following method using a vapor phase growth method, the Fe—B—R-based permanent magnet and an aluminum piece are placed in a processing vessel, and Among them, a method of applying vibration to both and / or stirring both is mentioned as a desirable method.

 (1) Vapor growth method

 Known methods such as a vacuum deposition method, an ion sputtering method, and an ion plating method can be used as a vapor phase growth method that can be employed to form the aluminum film. The aluminum film may be formed under the general conditions of each method.However, from the viewpoint of the denseness of the formed film, the uniformity of the film thickness, the film formation speed, etc., the vacuum evaporation method or the ion plating method is used. It is desirable to adopt it. It is needless to say that the magnet surface may be subjected to a known cleaning treatment such as cleaning, degreasing, or sputtering before forming the skin.

 It is desirable that the temperature of the magnet during film formation be set to 200 ° (: up to 500 ° C. If the temperature is less than 200 ° C, a film having excellent adhesion to the magnet surface is formed. If the temperature exceeds 500 ° C, the film may crack during the cooling process after the film is formed, and the film may peel off from the magnet.

 If the thickness of the aluminum film is less than 0.01 m, excellent corrosion resistance may not be exhibited, and if it exceeds 50 / im, not only may the production cost be increased, but also the magnet may be effective. 0.01 zm to 50 m is desirable, but 0.05 / im to 25 m is more desirable because the volume may be small.

 (2) A method in which a Fe—B—R-based permanent magnet and an aluminum piece are placed in a processing container, and both are vibrated and Z or both are stirred in the processing container. The pieces can be of various shapes such as needle-like (wire-like), columnar, lump, etc. In order to efficiently generate aluminum fine powder which is a constituent source of aluminum film From the viewpoint of such reasons, it is desirable to use a needle-shaped or column-shaped one with a sharp end.

The size (major axis) of the aluminum piece is preferably 0.05 mm to 10 mm, more preferably 0.3 mm to 5 mm, and still more preferably 0.5 mm, from the viewpoint of efficiently producing aluminum fine powder. ~ 3mm. Aluminum two The rubber pieces having the same shape and the same dimensions may be used, or the pieces having different shapes and different dimensions may be mixed and used.

 Vibration and Z or agitation of the magnet and the aluminum piece are desirably performed dry in consideration of the fact that both are easily oxidized and corroded, and can be performed in an air atmosphere at room temperature. The processing vessel that can be used in the present invention does not require a complicated apparatus, and may be, for example, a processing chamber of a barrel apparatus. As the barrel device, a known device such as a rotary type, a vibration type, and a centrifugal type can be used. In the case of a rotary type, it is desirable that the number of rotations be 20 rpm to 50 rpm. In the case of the vibration type, it is desirable that the frequency be 50 Hz to 100 Hz and the vibration amplitude be 0.3 mm to 10 mm. In the case of the centrifugal type, it is desirable that the rotation speed is set to 70 rpm to 200 rpm.

 The amount of the magnet and the aluminum pieces to be put in the processing container is preferably 20% to 90% of the volume of the processing container. If it is less than 20 Vo 1%, the treatment amount is too small to be practical, and if it exceeds 90 Vo 1%, a film may not be formed efficiently. Also, the ratio of magnets and aluminum pieces to be placed in the processing vessel is desirably 3 or less in terms of volume ratio (magnet / aluminum pieces). If the volume ratio exceeds 3, it takes a long time to form a film, which may not be practical. Although the processing time depends on the processing amount, it is usually 1 hour to 10 hours.

 According to the above method, aluminum fine powder generated from aluminum pieces is applied to the magnet surface to form an aluminum film. The phenomenon in which aluminum fines adhere to the magnet surface is considered to be a kind of mechanochemical reaction. Aluminum fines adhere firmly to the magnet surface, and the resulting aluminum film shows excellent corrosion resistance. From the viewpoint of ensuring sufficient corrosion resistance, as described above, it is desirable that the film thickness be 0.01 m or more. Although the upper limit of the film thickness is not particularly limited, since it takes time to form an aluminum film having a film thickness of more than 1 m, this method is used as a method for forming an aluminum film having a film thickness of 1 m or less. Are suitable.

After forming an aluminum film on the magnet surface, heat treatment can be performed to increase the adhesion between the magnet surface and the aluminum film. If the temperature of the heat treatment is less than 200 ° C, the interfacial reaction between the magnet and the aluminum film does not proceed sufficiently and If the temperature exceeds 500 ° C., the magnetic properties of the magnet may be deteriorated, and the aluminum film may be dissolved. Therefore, the heat treatment is desirably performed at 200 ° C to 500 ° C, but from 200 ° C to 250 ° C from the viewpoint of productivity and manufacturing cost. More desirable.

 Next, a method of forming a chemical conversion film containing at least one selected from the group consisting of titanium and zirconium, phosphorus, oxygen and fluorine on the aluminum film will be described. The method includes, for example, at least one selected from a titanium compound and a zirconium compound, at least one selected from phosphoric acid, condensed phosphoric acid, phytic acid, a hydrolyzate of phytic acid and a salt thereof, and fluorine. A method of applying a treatment liquid containing a compound and performing a drying treatment may be mentioned.

 The treatment solution dissolves in water at least one selected from a titanium compound and a zirconium compound, at least one selected from phosphoric acid, condensed phosphoric acid, phytic acid, a hydrolyzate of phytic acid and salts thereof, and a fluorine compound. Adjusted. Examples of the titanium compound contained in the treatment liquid include fluorotitanic acid, an alkali metal salt or an alkaline earth metal salt of a fluorothiocyanic acid, a ammonium salt, and a sulfate or a nitrate of titanium. Examples of the zirconium compound include fluorodisilconic acid, alkali metal salts and alkaline earth metal salts of fluorodisilconic acid, ammonium salts, and zirconium sulfates and nitrates. The content in at least one treatment liquid selected from a titanium compound and a zirconium compound is desirably 1 ppm to 2000 ppm in terms of metal, and more desirably 10 ppm to 100 ppm in terms of metal. If the content is less than 1 ppm, it may not be possible to form an artificial skin, and if it is more than 2000 ppm, the cost may increase.

As the condensed phosphoric acid contained in the treatment liquid, pyrophosphoric acid, tripolyphosphoric acid, phosphoric acid, ultraphosphoric acid and the like can be used. Examples of the phytic acid hydrolyzate include myo-inositol diphosphate, triphosphate, tetraphosphate, and pentaphosphate. As the salts of phosphoric acid, condensed phosphoric acid, phytic acid and phytic acid hydrolyzate, respective ammonium salts, alkali metal salts and alkaline earth metal salts can be used. Rin When an acid, condensed phosphoric acid, or a salt thereof is used, the content in the treatment solution is preferably 1 ppm to 200 ppm, more preferably 5 ppm to 100 ppm in terms of phosphoric acid. . If the content is less than 1 ppm, a conversion coating may not be formed, and if the content is more than 2000 ppm, the adhesion of the conversion coating to a magnet may be affected. For the same reason, when phytic acid, hydrolyzate of phytic acid and their salts are used, their content in the treated solution is 50 ppn! In terms of phytic acid. 1100000 ppm is desirable, and 100 ppm〜500 ppm is more desirable.

 Examples of the fluorine compound contained in the treatment liquid include the above-mentioned fluorotitanic acid and salts thereof, fluorodiconic acid and salts thereof, hydrofluoric acid, ammonium fluoride, ammonium hydrogenfluoride, sodium fluoride, hydrofluoric acid and the like. Sodium hydride or the like can be used. The content of the fluorine compound in the treatment solution is desirably from lOppm to 100ppm, more desirably from 50ppm to 500ppm in terms of the fluorine concentration. If the content is less than 10 ppm, the aluminum film surface may not be efficiently etched.If the content is more than 100 ppm, the etching rate is faster than the film forming rate, and it is difficult to form a uniform film. This is because there is a possibility of becoming. It is desirable that the pH of the treatment liquid is adjusted to 1 to 6. If the pH is less than 1, excessive etching of the aluminum film surface may occur, and if the pH exceeds 6, the stability of the processing solution may be affected.

 In addition to the above components, the treatment solution improves the reactivity of the chemical conversion treatment, improves the stability of the treatment solution, improves the adhesion of the chemical conversion film to the magnet, and adheres when the magnet is incorporated into the component. Organic acids such as tannic acid, oxidizing agents for the purpose of improving adhesiveness with

(Hydrogen peroxide, chloric acid and its salts, nitrous acid and its salts, nitric acid and its salts, tungstic acid and its salts, molybdate acid and its salts), and water-soluble resins such as water-soluble polyamides Is also good.

When the processing solution itself lacks storage stability, it may be adjusted as needed. Examples of the treatment liquid that can be used in the present invention include a treatment liquid prepared from PARCOAT 375 3 (product name · manufactured by Nippon Paricalizing Co., Ltd.), PARCOAT 3 756 NA, and PARCOTE 3 756 NB (both product names · manufactured by Nippon Pharmaceuticals Co., Ltd.) And a treatment liquid adjusted from the above.

 As a method for applying the treatment liquid to the surface of the aluminum film, an immersion method, a spray method, a spin coating method, or the like can be used. When applying, the temperature of the processing solution is preferably 20 to 80 ° C. If the temperature is lower than 20 ° C, the reaction may not proceed, and if it is higher than 80 ° C, the stability of the processing solution may be affected. Processing time is typically 10 seconds to 10 minutes.

 After applying the treatment liquid to the aluminum film surface, perform the drying treatment. If the drying temperature is lower than 50 ° C, it cannot be dried sufficiently, which may cause deterioration of the appearance and affect the adhesiveness with the adhesive used when incorporating the magnet into the part. If the temperature exceeds 250 ° C, the formed chemical conversion film may decompose. Therefore, the temperature is desirably 50 ° C to 250 ° C, but is more desirably 50 ° C to 150 ° C from the viewpoint of productivity and manufacturing cost. Usually, the drying time is 5 seconds to 1 hour.

 The chemical conversion film formed by the above method and containing at least one selected from titanium and zirconium, phosphorus, oxygen and fluorine as the constituent elements is firmly adhered to the magnet through the aluminum film. If the film thickness is 0.01 urn or more, sufficient corrosion resistance can be obtained. Also, during the chemical conversion treatment, the phosphoric acid and complex phosphoric acid in the treatment solution react with Nd and Fe, which are magnet materials on the magnet surface, to form a passivation film. It is considered that even if there is a part that is not, the corrosion resistance of this part is supplemented. Although the upper limit of the thickness of the chemical conversion film is not limited, it is preferably 1 xm or less, more preferably 0.3 m or less, from the viewpoint of the demand for miniaturization of the magnet itself and the manufacturing cost.

The content of titanium and Roh or zirconium in the chemical conversion coating, the coating per 0. lmg~l 0 Omg formed on the magnet surface lm ² is desirable, Lmg～50m g is more preferable. If the content is less than 0.1 mg, sufficient corrosion resistance may not be obtained, and if it is more than 10 mg, the cost may be increased.

The content of phosphorus in the chemical conversion coating per film is formed on the magnet surface lm ² 0. lmg~: 10 Omg desirably, 1 mg to 5 Omg is more desirable. Content is 0. If the amount is less than 1 mg, sufficient corrosion resistance may not be obtained, and if the amount is more than 100 mg, the adhesiveness to an adhesive used when a magnet is incorporated into a component may be affected.

Oxygen in the chemical conversion film is combined with titanium, zirconium and phosphorus, and organic acids added to the processing solution to improve the adhesion with the adhesive used when assembling the magnet into components. Is present in the chemical conversion film as a constituent element of Chemical oxygen content in the coating, per film is formed on the magnet surface lm ² 0. ² mg ~ 30 Omg is desirable. If the content is less than 0.2 mg, sufficient corrosion resistance may not be obtained, and if it is more than 30 Omg, the adhesion to the adhesive used when assembling magnets into parts may be affected. Because.

Fluorine in the chemical conversion coating is due like those bound to Z r such as free fluorine ions and Z r F ₄ HP_〇 ₄ present in the processing solution to etch the Aruminiumu film surface, chemical It is taken into the film when the film is formed. The content of fluorine in the chemical conversion coating, the coating per 0. 05mg~ 10 Omg formed on the magnet surface lm ² is desirable, 0. 1 mg to 5 Omg is more desirable. If the content is less than 0.05 mg, sufficient corrosion resistance may not be obtained, and if it is more than 10 Omg, it may affect the adhesiveness with the adhesive used when incorporating magnets into parts Because.

Among the chemical conversion films formed by the above method and containing at least one selected from the group consisting of titanium and zirconium, phosphorus, oxygen and fluorine, also near the surface of the film (for example, from the surface of the film to the surface of the film). (Thickness area of 002), the ratio of the mole number of phosphorus to the mole number of titanium and Z or zirconium is greater than the ratio of the total mole number of the coating, and the content of titanium, Z or zirconium near the coating surface It is desirable that the ratio of the number of moles of phosphorus to the number of moles is 1 or more, preferably 2 or more, and more preferably 3 or more. Phosphoric acid or complex phosphoric acid captures moisture and can more effectively prevent the water that causes corrosion from reaching the magnet surface This is because it is considered to be something. In order to form such a film, a small amount selected from a titanium compound and a zirconium compound in the treatment liquid is required. The ratio of at least one kind of mole number (in terms of phosphorus) selected from phosphoric acid, condensed phosphoric acid, acid, hydrolyzate of phytic acid and salts thereof to at least one kind of mole number (in terms of metal) is at least one. It is desirable to use one or more processing solutions. As a pre-process for forming the chemical conversion film on the aluminum film, shot beaning (a method of modifying the surface by colliding hard particles) may be performed. By performing shot pinning, the aluminum film can be smoothed and a thin chemical film having excellent corrosion resistance can be easily formed.

 The powder used for shot peening preferably has a hardness equal to or higher than the hardness of the formed aluminum film, and includes, for example, spherical hard powder having a Mohs hardness of 3 or more, such as steel pole or glass beads. If the average particle size of the powder is less than 30 zm, the pressing force against the aluminum film is small, and it takes time to process. On the other hand, if it exceeds 3000 m, the surface roughness may be too rough and the finished surface may be uneven. Therefore, the average particle size of the powder is preferably 30 to 3000 xm, more preferably 40 to 2000 m.

The injection pressure in shot peening is desirably 1.0 kgZcm ^{2 to} 5.0 kg / cm ² . Injection pressure takes time for small pressing force process for metal coating is less than ^{1. 0 kg / cm 2, 5.} 0 kg / cm 2 to greater than the pressing force against the metal coating is unevenly This is because the surface roughness may be deteriorated. The injection time in shot peening is preferably 1 minute to 1 hour. If the injection time is less than 1 minute, uniform treatment may not be performed on the entire surface, and if it exceeds 1 hour, the surface roughness may be deteriorated.

 The rare earth element (R) in the Fe—B—R permanent magnet used in the present invention is at least one of Nd, Pr, Dy, Ho, Tb, and Sm, and further, La, Ce, Gd , Er, Eu, Tm, Yb, Lu, and Y are desirable.

 Normally, one kind of R is sufficient, but in practice, a mixture of two or more kinds (such as mischid metal dizyme) can be used for convenience and other reasons.

If the content of R in the Fe-B-R permanent magnet is less than 10 atomic%, Since the structure has the same cubic structure as Fe, high magnetic properties, especially high coercive force (iHe) cannot be obtained. On the other hand, if it exceeds 30 atomic%, R-rich nonmagnetic phase increases. However, since the residual magnetic flux density (Br) is lowered and a permanent magnet having excellent characteristics cannot be obtained, the R content is desirably 10 to 30 atomic% of the composition.

 If the Fe content is less than 65 at%, Br decreases, and if it exceeds 80 at%, high iHe cannot be obtained. Therefore, the content of 65 to 80 at% is desirable.

 In addition, by replacing a part of Fe with Co, the temperature characteristics can be improved without impairing the magnetic characteristics of the obtained magnet, but when the Co substitution amount exceeds 20% of Fe, However, it is not desirable because the magnetic characteristics deteriorate. When the amount of Co substitution is 5 atomic% to 15 atomic%, Br increases as compared with the case where no substitution is made, so that it is desirable to obtain a high magnetic flux density.

 If the B content is less than 2 atomic%, the rhombohedral structure becomes the main phase, and a high iHc cannot be obtained. If the B content exceeds 28 atomic%, the B-rich non-magnetic phase increases, and the Br decreases, resulting in excellent. Since a permanent magnet having the above characteristics cannot be obtained, the content of 2 to 28 atomic% is desirable.

 In addition, to improve magnet manufacturability and reduce prices, 2.0% or less? , 2.0 wt% or less of S, at least one kind of S may be contained in a total amount of 2.0 wt% or less. Further, by substituting a part of B with C of 30 wt% or less, the corrosion resistance of the magnet can be improved.

 Further, at least one of Al, Ti, V, Cr, Mn, Bi, Nb, Ta, Mo, W, Sb, Ge, Sn, Zr, Ni, Si, Zn, Hf, Ga The addition of one kind is effective in improving the coercivity / demagnetization curve squareness, improving the manufacturability, and reducing the price. In order to make the maximum energy product (BH) max equal to or more than 2 OMGOe, Br must be at least 9 kG or more. .

 In addition, the Fe—B—R permanent magnets may contain impurities inevitable in industrial production in addition to R, Fe, and B.

Further, among the Fe—B—R-based permanent magnets used in the present invention, a compound having a tetragonal crystal structure with an average crystal grain size in the range of 1 ^ 111 to 80 / m is defined as a main phase. It is characterized by containing 1% to 50% by volume of non-magnetic phase (excluding oxide phase), i He ≥ 1 kOe, Br> 4 kG, (BH) max ≥ 10 Indicates MGO e, and the maximum value of (BH) max reaches 25 MGOe or more.

 In addition, another film may be laminated on the chemical conversion film of the present invention. By adopting such a configuration, it is possible to enhance and supplement the characteristics of the chemical conversion film, or to impart further functionality.

Example

 For example, as described in U.S. Pat. No. 4,770,723, 17Nd-lP obtained by pulverizing a publicly known forged ingot, finely pulverizing it, and performing molding, sintering, heat treatment and surface processing. The following experiment was conducted using a sintered magnet of 23mm x 10mm x 6mm (hereinafter referred to as "magnet test piece") with r-75Fe-7B composition. In the following experiments, the film thickness of the aluminum film was measured using a fluorescent X-ray film thickness meter (apparatus: SFT-7000: manufactured by Seiko Electronics Co., Ltd.). The thickness of the artificial skin was determined by X-ray photoelectron spectroscopy (XPS) in the depth direction of the film (ESCA-850: manufactured by Shimadzu Corporation). The content of each component in the coating was measured by X-ray fluorescence intensity (RIX-3000: manufactured by Rigaku Corporation). The present invention is not limited to application to Fe—B—R based sintered magnets, but is also applicable to Fe—B—R based magnets.

Experimental example 1:

To magnet test piece, the vacuum vessel was evacuated to less than 1 X 10- ⁴ P a, Ar gas pressure 1 0 P a, under conditions of a bias voltage one 400V, 35 minutes, subjected to sputtering, magnet surface Was cleaned.

 8 1 "gas pressure 0.2 Pa, bias voltage 1 50 V, magnet temperature 250 ° C, using metal aluminum as target, perform arc ion plating for 15 minutes, aluminum film on magnet surface The aluminum film thus obtained had a thickness of 0.5 m.

35 g of PARCORT 3753 (product name, manufactured by Nippon Pachiriki Rising Co., Ltd.) was dissolved in 1 liter of water to obtain a treatment solution (pH 3.8). In this treatment liquid, a magnet having an aluminum coating on the magnet surface was immersed for 1 minute at a bath temperature of 40 ° C. to form a chemical conversion coating. Thereafter, a titanium-containing chemical conversion film having a thickness of 0.1 m was formed on the aluminum film by performing a drying treatment at 100 ° C for 20 minutes. The titanium content in the conversion coating was 10 mg (per lm ^{2 of the} magnet surface), the phosphorus content was 7 mg (same), the oxygen content was 21 mg (same), and the fluorine content was 2 mg (same).

 A magnet having a titanium-containing chemical conversion coating on the magnet surface via an aluminum coating, obtained by the above method, was allowed to stand at a temperature of 80 ° C and a relative humidity of 90% at high temperature and high humidity for 300 hours. An accelerated test was performed. Table 1 shows the magnetic properties before and after the test and the appearance changes after the test. As a result, it was found that the magnet obtained did not substantially deteriorate in magnetic properties and appearance even when left for a long time under high-temperature and high-humidity conditions, and sufficiently satisfied the required corrosion resistance.

Experimental example 2:

 After cleaning the magnet test piece under the same conditions as in Experimental Example 1, the aluminum wire was heated as the coating material under the conditions of Ar gas pressure of 1 Pa and a voltage of 1.5 kV. The magnet was evaporated and ionized, and an aluminum film was formed on the magnet surface by the ion plating method for 1 minute, and then allowed to cool. The film thickness of the obtained aluminum film was 0.1 μμπι.

Then, together with the pressurized gas consisting of N ₂ gas, spherical glass bead powder with an average particle size of 120; m and Mohs hardness of 6 was sprayed onto the aluminum film surface at an injection pressure of 1.5 kgZcm ^{2 for} 5 minutes. Sprayed and shot peened.

PARCO 3756 NA and PARCO 3756 NB (both are product names; manufactured by Nippon Parkerizing Co., Ltd.) 10 g each was dissolved in 1 liter of water to obtain a treatment solution. The ratio is 6.2 / pH 3.2). The magnet having an aluminum film on the magnet surface was immersed in this treatment solution at a bath temperature of 50 ° C for 1 minute and 30 seconds to form a chemical conversion film, followed by drying at 120 ° C for 20 minutes. A zirconium-containing conversion coating having a thickness of 0.07 m was formed on the aluminum coating. The zirconium content in the said chemical conversion coating is 16 mg (per above magnet surface 1 m ^2), with phosphorus content l lmg (same), oxygen content 50 mg (same), fluorine content 3 mg (same) there were.

A zirconium layer is formed on the magnet surface obtained through the above method, An accelerated corrosion resistance test under the same conditions as in Experimental Example 1 was performed on a magnet having a chemical conversion film containing a rubber. The results are shown in Table 1. As a result, the obtained magnet was found to sufficiently satisfy the required corrosion resistance.

Experimental example 3:

 1 50 magnet specimens (apparent capacity 0.5 liters, weight 1.6 kg) and a short cylindrical aluminum piece 0.8 mm in diameter and 1 mm long (apparent capacity 20 liters, weight 100 kg) It is charged into the processing chamber of a 50-liter vibration barrel unit (total input is 40 V o 1% of the processing chamber volume), and the processing is performed dry under the conditions of a vibration frequency of 60 Hz and a vibration amplitude of 1.8 mm. After 5 hours, an aluminum film was formed on the magnet surface. The thickness of the obtained aluminum film was 0.05 zm.

The above-mentioned magnet with an aluminum film on the magnet surface was immersed in the treatment solution described in Experimental Example 2 at a bath temperature of 50 ° C for 1 minute and 30 seconds to form a chemical conversion film, and then dried at 120 ° C for 20 minutes. Thus, a zirconia-containing chemical conversion film having a thickness of 0.008111 was formed on the aluminum film. The zirconium content in the said chemical conversion coating is 16 mg (per above magnet surface lm ^2), the phosphorus content is 12 mg (the), the oxygen content is 3 8 mg (same), fluorine content met 3 mg (same) Was.

 The magnet having a zirconium-containing chemical conversion coating on the magnet surface via an aluminum coating obtained by the above method was subjected to an accelerated corrosion resistance test under the same conditions as in Experimental Example 1. The results are shown in Table 1. As a result, it was found that the obtained magnet sufficiently satisfied the required corrosion resistance.

Experimental example 4:

 After cleaning the magnet test piece under the same conditions as in Experimental Example 1, arc plating was performed for 2.5 hours, an aluminum film was formed on the magnet surface, and the magnet was allowed to cool. The thickness of the obtained aluminum film was 5 m.

The magnet with an aluminum film on the magnet surface was immersed in the treatment solution described in Experimental Example 1 at a bath temperature of 40 ° C for 1 minute to form a chemical conversion film, and then dried at 100 ° C for 20 minutes. As a result, a titanium-containing chemical conversion film having a thickness of 0.09 m was formed on the aluminum film. Said chemical titanium content in the formed coating 9m g (per above magnet surface lm ^2), the phosphorus content is 6 mg (same), oxygen content 20 mg (same), fluorine-containing The dose was 2 mg (same as above).

 The magnet with the titanium-containing chemical conversion coating on the magnet surface via the aluminum coating obtained by the above method is left under the conditions of high temperature and high humidity of 80 ° C and 90% relative humidity for 1 000 hours, corrosion resistance An accelerated test was performed. Table 2 shows the magnetic properties before and after the test and the appearance changes after the test. As a result, it was found that the magnets obtained sufficiently satisfied the required corrosion resistance even when left under high-temperature and high-humidity conditions for a long time with little deterioration in magnetic properties and appearance.

Experimental example 5:

 An aluminum coating was formed on the magnet surface by the ion plating method for 10 minutes under the same conditions as in Experimental Example 2, and the magnet was allowed to cool. The thickness of the obtained aluminum film is 10 m / cm.

Then, along with the pressurized gas consisting of N ₂ gas, spherical glass beads having an average particle size of 120 ^ m and Mohs hardness of 6 were sprayed onto the aluminum film surface at an injection pressure of 1.5 kgZcm ^{2 for} 5 minutes. Sprayed and shot peened.

A magnet with an aluminum film on the magnet surface was immersed in the treatment solution described in Experimental Example 2 at a bath temperature of 50 ° C for 1 minute and 30 seconds to form a chemical conversion film, and then dried at 120 ° C for 20 minutes. Thus, a zirconia-containing chemical conversion film having a thickness of 0.0 was formed on the aluminum film. The zirconium content in the said chemical conversion coating is 15 mg (per above magnet surface lm ^2), the phosphorus content is 12 mg (the) Meet oxygen content 4 7 mg (same), fluorine content 2 mg (same) Was.

 The accelerated corrosion resistance test under the same conditions as in Experimental Example 4 was performed on the magnet having a zirconium-containing chemical conversion film via an aluminum film on the magnet surface obtained by the above method. The results are shown in Table 2. As a result, the obtained magnet was found to sufficiently satisfy the required corrosion resistance.

The ratio of the number of moles of phosphorus to the number of moles of zirconium in the thickness area of 0.002 m from the surface of the zirconium-containing chemical conversion coating was measured by X-ray photoelectron spectroscopy (XPS). ESCA-850: Shimadzu Corporation). On the other hand, based on the moles of zirconium and phosphorus measured by the fluorescent X-ray intensity, the titanium When the ratio of the number of moles of phosphorus to the number of moles of zirconium was calculated, it was 2.

Example 6:

After the magnet test piece was cleaned in Experimental Example 1 under the same conditions, conditions of A r gas pressure 1 X 10- ² P a, using an ingot of metallic aluminum as a coating material, and evaporated by heating Re this An aluminum film was formed on the surface of the magnet by a vacuum evaporation method for 50 minutes, and then allowed to cool. The thickness of the obtained aluminum film was 8.

A magnet having an aluminum coating on the magnet surface was immersed in the treatment solution described in Experimental Example 2 at a bath temperature of 50 ° C for 1 minute and 30 seconds to form a chemical conversion film, and then dried at 120 ° C for 20 minutes. As a result, a zirconium-containing chemical conversion film having a thickness of 0.06 ^ m was formed on the aluminum film. The zirconium content in the said chemical conversion coating is 15 mg (per above magnet surface lm ^2), the phosphorus content is 13 mg (the) Meet oxygen content 3 5 mg (same), fluorine content 2 mg (same) Was.

 The accelerated corrosion resistance test under the same conditions as in Experimental Example 4 was performed on the magnet having a zirconium-containing chemical conversion film via an aluminum film on the magnet surface obtained by the above method. The results are shown in Table 2. As a result, it was found that the obtained magnet sufficiently satisfied the required corrosion resistance.

Corrosion resistance 前 Before t test Corrosion resistance After t test Appearance after test

B kG) iHc (kOe) (BH) max (MGOe) BKkG) iHc (kOe) (BH) max (MGOe)

Experimental example 1 11.3 16.7 30.6 11.2 16.5 29.8 No change Experimental example 2 11.3 16.6 30.5 11.3 16.4 29.8 No change Experimental example 3 11.4 16.7 30.6 11.1 16.4 29.7 No change Comparative example 1 11.3 16.7 30.5 10.6 15.8 27.3 Head part Comparative example 2 11.4 16.6 30.5 10.1 15.3 26.5 Departures Table 2

Comparative Example 1:

 After degreased and pickled the magnet specimen, dipped in a treatment solution consisting of zinc 4.6 gZ and phosphate 17.8 gZl at a bath temperature of 70 ° C, and phosphoric acid with a film thickness of 1 m was applied to the magnet surface. A salt film was formed. The obtained magnet was subjected to a corrosion resistance acceleration test under the same conditions as in Experimental Example 1. The results are shown in Table 1. As a result, the obtained magnets deteriorated and caused magnetic properties.

Comparative Example 2:

 An accelerated corrosion resistance test was performed on the magnet specimen under the same conditions as in Experimental Example 1. The results are shown in Table 1. As a result, the magnet test piece caused deterioration of magnetic properties and sales.

Comparative Example 3:

 The accelerated corrosion resistance test under the same conditions as in Experimental Example 4 was performed on the magnet having an aluminum film on the surface of the magnet subjected to shot peening in Experimental Example 5. The results are shown in Table 2. As a result, the obtained magnet deteriorated and caused magnetic properties.

Comparative Example 4:

After cleaning the magnet with the aluminum film on the surface of the shot-been magnet in Experimental Example 5, 300 gZ of sodium hydroxide and 40 g of zinc oxide / 1 gZ of ferric chloride, 30 g / K of rossel salt The aluminum film was immersed in a treatment solution at a bath temperature of 23 ° C, and the surface of the aluminum film was replaced with zinc. In addition, nickel sulfate 240 g / chloride Nickel 48 gZ 1, nickel carbonate appropriate amount (pH adjustment), boric acid 30 g / 1 consists of a bath temperature 55 ° C, pH 4. Using the second plated liquid, an electrical plated Te to a current density of 1. 8AZdm ² A nickel film having a thickness of 0.9 xm was formed on the aluminum film whose surface was replaced with zinc. The obtained magnet was subjected to an accelerated corrosion resistance test under the same conditions as in Experimental Example 4. The results are shown in Table 2. As a result, the resulting magnet deteriorated in magnetic properties and a part of the nickel film was peeled off.

Industrial applicability

 The permanent magnet according to the present invention, which has a conversion coating containing at least one selected from zirconium and titanium as a constituent element, phosphorus, oxygen and fluorine, on the surface of the Fe—B—R-based permanent magnet through an aluminum coating. Since the chemical conversion film is firmly adhered to the magnet via the aluminum film, it has excellent corrosion resistance, and its magnetic properties are maintained even when left for a long time under high temperature and humidity conditions of 80 ° C and 90% relative humidity. Demonstrate stable and high magnetic properties without deterioration. Further, hexavalent chromium is not contained in the film.

Claims

The scope of the claims 1. It is necessary to have a conversion coating containing at least one selected from titanium and zirconium, phosphorus, oxygen and fluorine as constituent elements on the surface of the Fe—B—R permanent magnet through an aluminum coating. Features permanent magnet.  2. The permanent magnet according to claim 1, wherein the thickness of the aluminum film is 0.01 m to 50 im.  3. The permanent magnet according to claim 1, wherein the chemical conversion film has a thickness of 0.01 ^ m to lxm. 4. Permanent range described first of claims, wherein the amount of titanium and Z or zirconium in the chemical conversion coating is a 0. lmg~l 0 Omg per film formed on the magnet surface 1 m ² magnet. 5. Chemical scope first term permanent magnet according to claim, wherein the amount of phosphorus in the coating is a film per 0. lmg~l 0 Omg formed on the magnet surface lm ^2. 6. The permanent magnet according to claim 1, wherein the oxygen content in the chemical conversion film is 0.2 mg to 30 Omg per film formed on 1 m ^{2 of the} magnet surface. 7. Chemical scope first term permanent magnet according to claim, wherein the content of fluorine in the film is the film per 0. 05mg~l 0 Omg formed on the magnet surface lm ^2. 8. The permanent magnet according to claim 1, wherein the ratio of the number of moles of phosphorus to the number of moles of titanium and Z or zirconium near the surface of the chemical conversion film is greater than the ratio in the entire chemical conversion film.  9. The permanent magnet according to claim 1, wherein the ratio of the number of moles of phosphorus to the number of moles of titanium and Z or zirconium near the surface of the chemical conversion film is 1 or more. 10. After an aluminum film is formed on the surface of the Fe—B—R permanent magnet, at least one selected from a titanium compound and a zirconium compound, phosphoric acid, and condensed phosphorus are formed on the aluminum film. A treatment liquid containing at least one selected from an acid, phytic acid, a hydrolyzate of phytic acid and a salt thereof, and a fluorine compound is applied and dried to obtain titanium and zirconia as constituent elements. A method for producing a permanent magnet, comprising forming a chemical conversion film containing at least one selected from the group consisting of phosphorus, oxygen and fluorine.  11. The manufacturing method according to claim 10, wherein the aluminum film is formed by a vapor growth method.  12. The method according to claim 11, wherein an aluminum film having a thickness of 0.01 m to 50 im is formed.  13. Put the Fe—B—R-based permanent magnet and the aluminum piece in a processing vessel, apply vibration to both, and / or stir both in the processing vessel to form an aluminum film. 11. The production method according to claim 10, wherein:  14. The production method according to claim 13, wherein an aluminum film having a thickness of 0.01 // m to l μιη is formed.  15. Hydrolysis products of phosphoric acid, condensed phosphoric acid, phytic acid, phytic acid and salts thereof based on at least one mole (metal conversion) selected from titanium compounds and zirconium compounds in the treatment solution 11. The production method according to claim 10, wherein a ratio of at least one selected mole content (in terms of phosphorus) is 1 or more.