JP2002118009A - Sintered rare-earth magnet and its manufacturing method - Google Patents

Abstract

(57) Abstract: 20 to 30% by weight of R (where R is Sm or two or more rare earth elements containing 50% by weight or more of Sm);
Fe10 to 45% by weight, Cu1 to 10% by weight, Zr0.
In a rare earth sintered magnet composed of 5 to 5% by weight, the balance being Co and inevitable impurities, the surface of the rare earth sintered magnet has C
A rare earth sintered magnet comprising a composite structure layer in which Sm ₂ O ₃ and / or CoFe ₂ O ₄ is present in o and / or Co and Fe. The present invention makes it possible to obtain a rare-earth sintered magnet that can be used for a motor or the like that does not cause hydrogen embrittlement for a long time even in a hydrogen atmosphere by the Sm ₂ Co ₁₇ based sintered magnet and the method for producing the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to Sm ₂ Co ₁₇ type magnets and a manufacturing method thereof used for a long time exposed such as a motor to a hydrogen atmosphere.

[0002]

2. Description of the Related Art A metal compound of a rare earth element and a transition metal has a property that hydrogen penetrates between crystal lattices, that is, absorbs and releases hydrogen in an alloy, and the property is used in various fields. Have been. For example, La
A hydrogen battery using a hydrogen storage alloy typified by Ni ₅ can be cited, and a rare earth sintered magnet can also be made of R ₂ Fe ₁₄ B
As a method for pulverizing a system alloy, it is further used as a method for manufacturing an R ₂ Fe ₁₄ B-based bonded magnet (HDDR, Japanese Patent Application Laid-Open No. 3-129702).

However, when hydrogen is absorbed and released in an alloy or a magnet, hydrogen embrittlement is caused. Therefore, when a motor or the like using a rare earth sintered magnet is used in a hydrogen atmosphere, the magnet material becomes There have been problems such as decomposition into powder, cracks and cracks.

At present, rare earth sintered magnets include R ₂ Fe ₁₄ B
System, SmCo ₃ system, Sm ₂ Co ₁₇ system and the like. In general, for hydrogen, 1 to 1
The structure of the 2-7 type crystal has a lower plateau pressure than the structure of the -5 type crystal and the structure of the 1-5 type crystal, that is, a rare earth-rich (hereinafter referred to as R-rich) alloy is more likely to absorb hydrogen. Tends to be embrittled with hydrogen.

In general, R ₂ Fe ₁₄ B-based magnets are subjected to surface treatment such as plating and resin coating for improving corrosion resistance, but they are not a means for preventing hydrogen embrittlement. To solve this problem, R ₂ Fe ₁₄
A method of incorporating a hydrogen storage alloy into a surface treatment film of a B-based magnet has been proposed (Japanese Patent Application Laid-Open No. H11-87119).
Since the R ₂ Fe ₁₄ B-based magnet produced by this method has an R-rich phase, it does not cause hydrogen embrittlement in a hydrogen atmosphere at a pressure of 0.1 MPa or less, but does not cause hydrogen embrittlement in a hydrogen atmosphere at a pressure exceeding that. Causes hydrogen embrittlement, and the magnet material is decomposed into powder, cracks, and cracks occur.

[0006] Like the R ₂ Fe ₁₄ B-based magnet, the SmCo ₅ -based magnet also has an R-rich phase and the main phase of SmCo ₅ -based magnet.
The plateau pressure of the _five phases is about 0.3 MPa. From this, in a hydrogen atmosphere at a pressure exceeding 0.3 MPa, hydrogen embrittlement is caused, and the magnet material is decomposed into powder, cracks and cracks occur.

The Sm ₂ Co ₁₇ based magnet has a main phase of 2-17 phase, is not R-rich compared to R ₂ Fe ₁₄ B-based and SmCo ₅ -based magnets, and does not contain an R-rich phase. Hard to cause. However, it has been known that, in a hydrogen atmosphere at a pressure exceeding 1 MPa, hydrogen embrittlement is caused, and the magnet material is decomposed into powder, cracks and cracks are formed as in other rare earth sintered magnets.

[0008]

SUMMARY OF THE INVENTION The present invention provides an Sm ₂ Co ₁₇ based sintered magnet which has solved the above-mentioned problems and a method for manufacturing the same. In other words, like conventional rare earth sintered magnets, Sm ₂ Co ₁₇ based sintered magnets which caused hydrogen embrittlement in a hydrogen atmosphere and decomposed the magnet material into powder, cracks, and cracks were solved. It is an object of the present invention to provide a manufacturing method thereof.

[0009]

Means for Solving the Problems and Embodiments of the Invention As a result of intensive studies to achieve the above object, the present inventor has found that Co and / or Co is present on the surface of a Sm ₂ Co ₁₇ based sintered magnet. And Sm ₂ O ₃ and / or CoFe ₂ O _{4 in} Fe
By forming a composite structure layer in which is present, hydrogen embrittlement does not occur even in a hydrogen atmosphere, and therefore, Sm ₂ which is preferably used for a motor or the like exposed to a hydrogen atmosphere for a long time
It has been found that a Co ₁₇ based sintered magnet can be obtained. Also, in this case, in producing the Sm ₂ Co ₁₇ based sintered magnet, the sintered magnet after sintering and aging is subjected to an optimal heat treatment after grinding, so that the surface of the magnet body has hydrogen resistance. It has been found that an excellent layer can be formed without deterioration of magnetic properties.

Furthermore, since the Sm ₂ Co ₁₇ based sintered magnet and the surface layer are easily chipped, it is difficult to handle it during assembling a product, and may cause chipping or chipping. Rare earth sintered magnets that have chipped, chipped, etc., do not affect magnetic properties, but have reduced hydrogen embrittlement resistance and may be equivalent to those without a surface layer. In other words, in a hydrogen atmosphere at a pressure exceeding 1 MPa, hydrogen embrittlement is caused, and the magnet material is powdered into powder,
Cracks and cracks may occur, but the above Sm ₂ C
o It has been found that applying a resin coating to the surface of the composite structure layer formed on the surface of the _17- based sintered magnet has an effect of preventing chipping and chipping. For these reasons, Sm suitable for use in motors and the like that are exposed to a hydrogen atmosphere for a long time
The inventors have found that a ₂ Co ₁₇ based sintered magnet can be obtained, and have accomplished the present invention.

That is, the present invention relates to R (where R is Sm or
Two or more rare earth elements containing 50% by weight or more of Sm) 20
-30% by weight, Fe 10-45% by weight, Cu 1-10 weight
%, Zr 0.5 to 5% by weight, balance Co and unavoidable
In a rare earth sintered magnet made of a pure material, the rare earth sintered magnet
Sm in Co and / or Co and Fe on stone surface _Two
O_ThreeAnd / or CoFe_TwoO_FourHas a composite tissue layer in which
The present invention provides a rare earth sintered magnet characterized in that: Change
A rare earth sintering with a resin coating formed on the surface of the composite structure layer
Provide magnets.

Further, the present invention relates to a method for producing R (where R is Sm or two or more rare earth elements containing 50% by weight or more of Sm) 20
-30% by weight, Fe 10-45% by weight, Cu 1-10% by weight, Zr 0.5-5% by weight, alloy consisting of Co and unavoidable impurities is cast, pulverized, finely pulverized, compacted in a magnetic field, and sintered. After successive aging to obtain a sintered magnet, and further cutting and / or polishing the surface of the sintered magnet to finish the surface, an oxygen partial pressure of 10 ^{−6 to} 152 torr is applied for 10 minutes to 20 minutes. The present invention provides a method for producing a rare earth sintered magnet, which is characterized by performing a heat treatment for a long time. In this case, after the heat treatment, the surface of the sintered magnet is preferably subjected to resin coating, in particular, spray coating, electrodeposition coating, powder coating or dipping coating.

Hereinafter, the present invention will be described in more detail.
The main components of the Sm ₂ Co ₁₇ permanent magnet alloy composition in the present invention are Sm or two or more rare earth elements containing 50% by weight or more of Sm, 20 to 30% by weight, Fe 10 to 45% by weight, C
u1 to 10% by weight, Zr 0.5 to 5% by weight, balance Co and inevitable impurities. The rare earth metal other than Sm is not particularly limited, and Nd, Ce,
Pr, Gd and the like can be mentioned. When the content of Sm in the rare earth element is less than 50% by weight, or when the amount of the rare earth element is less than 20% by weight or more than 30% by weight, it is impossible to have effective magnetic properties.

The Sm ₂ Co ₁₇ based sintered magnet of the present invention has a surface of a sintered magnet having the above-mentioned composition, on which Co and / or C
It has a composite structure layer in which Sm ₂ O ₃ and / or CoFe ₂ O ₄ is present in o and Fe, thereby effectively preventing hydrogen embrittlement from occurring.

In this case, the thickness of this layer is 0.1 μm or more and 3 mm or less, more preferably 1 to 500 μm, further preferably 1 to 50 μm, and particularly 0.01 to 2% with respect to the thickness of the magnet. Preferably, there is. When the thickness is less than 0.1 μm, effective hydrogen embrittlement resistance may not be obtained. Further, when the thickness exceeds 3 mm, although hydrogen embrittlement of the magnet body is prevented, the magnetic properties may be deteriorated by the layer itself.

The presence of Sm ₂ O ₃ and / or CoFe ₂ O ₄ usually means that Sm ₂ O ₃ or CoFe ₂ O ₄ is 1 to 10
It is in a state of being dispersed in the form of 0 nm particles.

On the surface as described above, Sm ₂ O ₃ and / or C
The method for producing a sintered magnet having a composite structure layer containing oFe ₂ O ₄ is not particularly limited, but an alloy having the above composition is cast and pulverized, more preferably pulverized,
Then, molding in a magnetic field, sintering, aging are sequentially performed to obtain a sintered magnet, and after further processing and finishing the surface, a method of manufacturing by performing a heat treatment or performing the aging treatment after the surface processing is preferably adopted. You.

Further, a preferred method of manufacturing the Sm ₂ Co ₁₇ based magnet according to the present invention will be described.
The m ₂ Co _17- based magnet alloy is obtained by melting and casting a raw material having the above composition range in a non-oxidizing atmosphere, for example, by high frequency melting.

Cast Sm_TwoCo₁₇Coarse magnetic powder
And then preferably with an average particle size of 1 to 10 μm, more preferably
Preferably, it is pulverized to about 5 μm. This coarse grinding
If N _TwoIn an inert gas atmosphere such as Ar, Ar, etc.
With a shear, brown mill, pin mill, hydrogen storage, etc.
Can be performed. Further, the pulverization may be performed by alcohol
Ball mill using water, hexane, etc. as solvent, N_Two,
Dry ball mill in an atmosphere of inert gas such as Ar, N
_TwoBy an inert gas stream such as Ar or Ar
Can be performed.

Next, the finely pulverized powder is preferably
With a press in a magnetic field capable of applying a magnetic field of Oe or more, preferably 500 kg / cm ² or more and 2000
Compression molding with a pressure of less than kg / cm ² . continue,
The obtained compression-molded body is subjected to a heat treatment furnace in a non-oxidizing atmosphere gas such as argon, preferably 1100 to 13
Sintering and solution treatment are performed at 00 ° C, more preferably 1150 to 1250 ° C, preferably for 0.5 to 5 hours.

Subsequently, preferably in an argon atmosphere,
It is kept at a temperature of 00 to 900 ° C, more preferably 750 to 850 ° C, preferably for 5 to 40 hours.
An aging treatment is performed in which the temperature is gradually cooled to 400 ° C. or lower at a temperature lowering rate of 400 ° C./min, and the surface is finished by cutting and / or polishing.

In the present invention, after the surface finishing, the oxygen partial pressure is from 10 ^{-6 to} 152 torr, preferably from 10 ^-3 to Torr.
152 torr, more preferably 1 to 152 torr, under an inert gas such as argon or nitrogen, air, or a vacuum atmosphere for 10 minutes to 20 hours, preferably 80 to 150 torr.
Heat treatment is performed at 850 ° C. In particular, when exposing under high hydrogen gas conditions, it is preferable to perform heat treatment at 400 to 600 ° C.
The oxygen partial pressure is preferably 1 to 152 to which the amount of oxygen is large.
The treatment is preferably performed in an atmosphere of rr. If the heat treatment time is less than 10 minutes, the dispersion varies depending on the heat treatment, and the heat treatment time is not appropriate, and the heat treatment for more than 20 hours is not efficient and may cause deterioration of magnetic properties. When the heat treatment temperature is less than 80 ° C., it takes a long time to obtain a rare earth magnet having a composite structure layer excellent in hydrogen embrittlement resistance, so that it is not efficient.
If the temperature is higher than ° C., the magnet undergoes phase transformation, and the magnetic properties may be deteriorated.

The heat treatment time is preferably 10 minutes to 10 hours, more preferably 1 to 5 hours. By such heat treatment, the surface of the composite structure layer, preferably the thickness, is formed as a hydrogen embrittlement preventing layer on the surface. A composite tissue layer of 0.1 to 3 μm is formed. As described above, this composite structure layer is mainly formed of fine Sm ₂ O ₃ and / or CoFe ₂ O _{4 in} Co and / or Co, Fe. In addition, the composite structure layer cannot prevent hydrogen embrittlement without the Co layer, and the layer itself may deteriorate magnetic properties.

In the present invention, Sm ₂ O ₃ and / or CoFe ₂ O ₄ are contained in the above-mentioned Co and / or Co and Fe.
A resin coating (resin coating by spray coating, electrodeposition coating, powder coating, dipping coating, etc.) is applied to the surface of the rare earth sintered magnet having the composite structure layer in which is present, and a resin coating is formed on the composite structure layer. Form.

The resin used for the resin coating is not particularly limited, and may be any of acrylic resin, epoxy resin, phenol resin, silicone resin, polyester resin, polyimide, polyamide, polyurethane resin and the like. A thermosetting resin or a thermoplastic resin can be used, but it is preferable to use a thermosetting resin from the viewpoint of heat resistance. The molecular weight (Mw) of the resin used is about 200 to several hundred thousand, preferably 200 to 10,000, and it is preferable to use an oil type resin.

The resin coating is selected from coating methods such as spray coating, electrodeposition coating, powder coating, and dipping coating. The thickness of the resin coating depends on the size of the magnet, but is 1 μm.
Not less than 3 mm and preferably not less than 10 μm and not more than 1 m
m or less, more preferably 10 μm or more and 50 μm or less. If the thickness is less than 1 μm, it is difficult to apply the coating uniformly, and therefore, it is difficult to obtain the effect of preventing chipping and chipping of the magnet. In addition, resin coating with a thickness exceeding 3 mm takes both time and cost, and efficient production may not be possible.

The thus obtained rare earth sintered magnet of the present invention is used for a motor or the like as a magnet which does not deteriorate due to cracking even in hydrogenation at 1 to 5 MPa (25 ° C.).

[0028]

Next, the present invention will be described specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1 A Sm ₂ Co ₁₇ based magnetic alloy was
Sm: 25.5% by weight, Fe: 14.0% by weight, Cu:
4.5% by weight, Zr: 3.0% by weight, the balance being Co, blended, melted in a high frequency melting furnace using an alumina crucible in an argon gas atmosphere, and cast by casting. did.

Next, the Sm ₂ Co _17- based magnet alloy was roughly pulverized to about 500 μm or less with a jaw crusher and a brown mill, and then finely pulverized to an average particle diameter of 5 μm by a jet mill using a nitrogen stream. The obtained finely pulverized powder was 1.5 t / cm in a magnetic field of 15 kOe by a press machine in a magnetic field.
Molded at a pressure of ² . After sintering the obtained molded body in an argon atmosphere at 1200 ° C. for 2 hours using a heat treatment furnace, a solution treatment was performed at 1185 ° C. for 1 hour in an argon atmosphere. After completion of the solution treatment, the mixture was rapidly cooled, and each of the obtained sintered bodies was maintained at 800 ° C. for 10 hours in an argon atmosphere, and gradually cooled to 400 ° C. at a temperature lowering rate of −1.0 ° C./min. A sintered magnet was produced. From the obtained sintered magnet,
Cut out the magnet to 5 × 5 × 5mm and vibrating
Sample Magnemeter (VSM)
Was used to measure the magnetic properties.

Next, the magnet was heated at 400 ° C. for 2 hours.
Heat treatment was performed in a vacuum (oxygen partial pressure: 10 ⁻³ torr), and then the temperature was gradually cooled to room temperature. For the hydrogen gas test sample obtained here, measurement of magnetic properties by VSM, XRD
And the structure was observed with a scanning electron microscope.

The hydrogen gas test sample was subjected to a hydrogen gas test in which the sample was sealed in a pressure vessel with hydrogen at 3 MPa and 25 ° C. and left for 24 hours, and then taken out. The magnetic properties of the removed magnet were measured by VSM.

Example 2 A sintered magnet was manufactured in the same composition and method as in Example 1. Next, the obtained sintered magnet was cut into 5 × 5 × 5 mm in the same manner as in Example 1, and VS
M was used to measure the magnetic properties.

Next, the magnet was heated at 500 ° C. for 2 hours.
Heat treatment was performed in a vacuum (oxygen partial pressure: 10 ⁻³ torr), and then the temperature was gradually cooled to room temperature. The magnetic properties of the obtained hydrogen gas test sample were measured by VSM, and the structure was observed by a scanning electron microscope.

Example 1 was applied to the hydrogen gas test sample.
A hydrogen gas test was performed under the same conditions as described above, and then the sample was taken out. The magnetic properties of the removed magnet were measured by VSM.

Comparative Example 1 A magnet was manufactured in the same composition and method as in Example 1. Next, the obtained sintered magnet was cut out into a size of 5 × 5 × 5 mm in the same manner as in Example 1, and the magnetic properties were measured by VSM. The hydrogen gas test sample obtained here was observed for its structure by a scanning electron microscope in the same manner as in Example 1, and the phase was identified by XRD.

Example 1 was applied to the hydrogen gas test sample.
A hydrogen gas test was performed under the same conditions as described above, and then the sample was taken out.

FIGS. 1 to 3 show backscattered electron images of Examples 1 and 2 and Comparative Example 1 by a scanning electron microscope. Table 1 shows heat treatment conditions, hydrogen gas test conditions, states after the hydrogen gas test, and Sm ₂ O _{3 in} Co and / or Co, Fe.
Indicates the thickness of the composite tissue layer in which is formed. Examples 1 and 2 showed no change in the hydrogen gas test, whereas Comparative Example 1 was pulverized to pieces. From this, it is clear that Examples 1 and 2 did not cause hydrogen embrittlement. Table 2 shows the magnetic properties of the magnet before and after the heat treatment and after the hydrogen gas test. After the heat treatment and the hydrogen gas test, Examples 1 and 2 showed almost no change in magnetic properties. This indicates that in Examples 1 and 2, there was no deterioration in magnetic properties due to heat treatment and no hydrogen embrittlement. In Comparative Example 1, the magnetic properties after the hydrogen treatment were not measurable because they were pulverized by the hydrogen treatment.

[0039]

[Table 1]

[0040]

[Table 2]

FIGS. 4 and 5 show X and Y of Example 1 and Comparative Example 1, respectively.
3 shows an RD image. The XRD image of Example 1 includes Sm ₂ Co ₁₇
Peaks of Co (bcc & fcc) and Sm ₂ O ₃ are observed in addition to the peak of Sm ₂ O _{3. In} the XRD image of Comparative Example 1, although the peak of Sm ₂ O ₃ is observed, the peaks of Co (bcc & fcc) and Sm ₂ O ₃ are observed. No peak is seen.

Example 3 A Sm ₂ Co _17- based magnet alloy was
Sm: 25.5% by weight, Fe: 20.0% by weight, Cu:
4.5% by weight, Zr: 3.0% by weight, the balance being Co, blended, melted in a high frequency melting furnace using an alumina crucible in an argon gas atmosphere, and cast by casting. did.

Next, the Sm ₂ Co _17- based magnet alloy was roughly pulverized to about 500 μm or less by a jaw crusher or a brown mill, and then finely pulverized to a mean particle size of 5 μm by a jet mill using a nitrogen stream. The obtained finely pulverized powder was 1.5 t / cm ^{2 in} a magnetic field of 15 kOe by a press machine in a magnetic field.
At a pressure of The obtained compact was sintered in an argon atmosphere at 1200 ° C. for 2 hours using a heat treatment furnace, and then subjected to a solution treatment at 1185 ° C. for 1 hour in an argon atmosphere. After completion of the solution treatment, the mixture was rapidly cooled, and each of the obtained sintered bodies was kept at 800 ° C. for 10 hours in an argon atmosphere, and gradually cooled to 400 ° C. at a temperature decreasing rate of −1.0 ° C./min. A sintered magnet was produced. From the obtained sintered magnet, a magnet was cut out to a size of 5 × 5 × 5 mm, and the magnetic properties were measured by VSM.

Next, the magnet was subjected to a heat treatment in the air (oxygen partial pressure: 152 torr) at 400 ° C. for 2 hours, and then gradually cooled to room temperature.

The hydrogen gas test sample was sealed in a pressure vessel under hydrogen, 3 MPa, and 25 ° C., subjected to a hydrogen gas test in which the sample was allowed to stand for 24 hours, and then taken out. The magnetic properties of the removed magnet were measured by VSM.

[Examples 4 and 5] The same composition as in Example 3,
A sintered magnet was produced by the method. Next, the obtained sintered magnet was cut out into a magnet of 5 × 5 × 5 mm in the same manner as in Example 3 and
Magnetic properties were measured by SM.

Next, the magnet was heated at 500 ° C. for 2 hours in a vacuum (oxygen partial pressure: 10 ⁻³ torr) [Example 4] at 600 ° C.
2 hours in a vacuum (oxygen partial pressure 10 ^-6 torr) [Example 5]
, And then gradually cooled to room temperature.
The hydrogen gas test sample obtained here was measured for magnetic properties using a VSM and observed for its structure using a scanning electron microscope.

For the hydrogen gas test sample, Example 3
A hydrogen gas test was performed under the same conditions as described above, and then the sample was taken out. The magnetic properties of the removed magnet were measured by VSM.

Comparative Example 2 A magnet was manufactured in the same composition and method as in Example 3. Next, the obtained sintered magnet was used in Example 3
A magnet was cut out to a size of 5 × 5 × 5 mm in the same manner as described above, and the magnetic properties were measured by VSM. Example 3 for the magnet
A hydrogen gas test was performed under the same conditions as described above, and then the sample was taken out.

Table 3 shows heat treatment conditions, hydrogen gas test conditions,
The state after the hydrogen gas test is shown. Examples 3, 4 and 5
Did not change in the hydrogen gas test, whereas Comparative Example 2 was crushed to pieces. From this, it is clear that Examples 3, 4 and 5 did not cause hydrogen embrittlement.

Table 4 shows the magnetic properties of the magnet before and after the heat treatment and after the hydrogen gas test. After the heat treatment and the hydrogen gas test, Examples 3, 4 and 5 showed almost no change in magnetic properties. This is shown in Examples 3, 4 and 5
This indicates that there was no deterioration in magnetic properties due to heat treatment and no hydrogen embrittlement. In Comparative Example 2, the magnetic properties after the hydrogen treatment could not be measured because the powder was pulverized by the hydrogen treatment.

[0052]

[Table 3]

[0053]

[Table 4]

Example 6 A sintered magnet was manufactured in the same composition and method as in Example 3. Next, the obtained sintered magnet was cut out to a size of 5 × 5 × 5 mm in the same manner as in Example 3.

Next, each of the magnets was heat-treated in the same manner as in Example 3 under the conditions shown in Table 5, and then gradually cooled to room temperature to obtain a hydrogen gas test sample.

The hydrogen gas test sample was placed in a pressure vessel with hydrogen, 3 MPa, 24 hours, 80 ° C., 120 ° C., 16
A hydrogen gas test was performed under the conditions shown in Table 5 at 0 ° C.
I took it out. Table 5 shows the results.

[0057]

[Table 5]

[Example 7] The Sm ₂ Co ₁₇ based magnet alloy was
Sm: 25.5% by weight, Fe: 16.0% by weight, Cu:
4.5% by weight, Zr: 3.0% by weight, the balance being Co, blended, melted in a high frequency melting furnace using an alumina crucible in an argon gas atmosphere, and cast by casting. did.

Next, the Sm ₂ Co _17- based magnetic alloy was roughly pulverized to about 500 μm or less with a jaw crusher and a brown mill, and then finely pulverized to a mean particle size of 5 μm by a jet mill using a nitrogen stream. The obtained finely pulverized powder was 1.5 t / cm in a magnetic field of 15 kOe by a press machine in a magnetic field.
Molded at a pressure of ² . The obtained compact was sintered in an argon atmosphere at 1195 ° C. for 2 hours using a heat treatment furnace, and then subjected to a solution treatment at 1180 ° C. for 1 hour in an argon atmosphere. After completion of the solution treatment, the mixture was rapidly cooled, and each of the obtained sintered bodies was kept at 800 ° C. for 10 hours in an argon atmosphere, and gradually cooled to 400 ° C. at a temperature decreasing rate of −1.0 ° C./min. A sintered magnet was produced. From the obtained sintered magnet, a magnet was cut out to a size of 5 × 5 × 5 mm, and the magnetic properties were measured by VSM.

Next, the magnet was heat-treated in air at 500 ° C. for 2 hours, and then gradually cooled to room temperature. The magnet obtained here was subjected to phase identification by XRD and observation of its structure by a scanning electron microscope.

FIG. 6 shows a backscattered electron image photograph of a magnet heat-treated at 500 ° C. for 2 hours in air by a scanning electron microscope. FIG. 9 shows an XRD image.

Subsequently, the magnets subjected to the heat treatment were coated with an epoxy resin by spraying. The hydrogen gas test sample obtained here was measured for magnetic properties by VSM.

The hydrogen gas test sample was sealed in a pressure vessel with hydrogen at 3 MPa and 25 ° C., subjected to a hydrogen gas test in which the sample was allowed to stand for 24 hours, and then taken out. The magnetic properties of the removed magnet were measured by VSM.

Example 8 A sintered magnet was manufactured in the same composition and method as in Example 7. Next, the obtained sintered magnet was cut into a magnet of 5 × 5 × 5 mm in the same manner as in Example 7, and the VSM was cut out.
Was used to measure the magnetic properties.

Next, the magnet was subjected to a heat treatment in air at 400 ° C. for 2 hours, and then gradually cooled to room temperature. The structure of the magnet obtained here was observed with a scanning electron microscope.

FIG. 7 shows a backscattered electron image photograph of a magnet subjected to heat treatment in air at 400 ° C. for 2 hours using a scanning electron microscope.

Subsequently, the magnets subjected to the above heat treatment were applied by spraying an epoxy resin in the same manner as in Example 7. The hydrogen gas test sample obtained here was measured for magnetic properties by VSM.

The hydrogen gas test sample was subjected to a hydrogen gas test under the same conditions as in Example 7 and then taken out.
The magnetic properties of the removed magnet were measured by VSM.

Example 9 A sintered magnet was manufactured in the same composition and method as in Example 7. Next, the obtained sintered magnet was cut out into a size of 5 × 5 × 5 mm in the same manner as in Example 7.

Next, the magnet was replaced by 500
The mixture was subjected to a heat treatment in the air at 2 ° C. for 2 hours, and then gradually cooled to room temperature.

Subsequently, as in Example 7, an epoxy resin was applied by spraying. Thereafter, the coated magnet was dropped on a steel plate from a height of 10 cm to obtain a hydrogen gas test sample.

Example 7 was applied to the hydrogen gas test sample.
A hydrogen gas test was performed under the same conditions as described above, and then the sample was taken out.

Comparative Example 3 A sintered magnet was manufactured in the same composition and method as in Example 7. Next, the obtained sintered magnet was cut into a magnet of 5 × 5 × 5 mm in the same manner as in Example 7, and the VSM was cut out.
Was used to measure the magnetic properties. The hydrogen gas test sample thus obtained was observed for its structure by a scanning electron microscope and identified its phase by XRD in the same manner as in Example 7.

FIG. 8 shows a backscattered electron image photograph by a scanning electron microscope. FIG. 10 shows an XRD image.
As can be seen from the comparison between FIG. 10 and FIG.
In the RD image, the peaks of Co (bcc & fcc), CoFe ₂ O ₄ and Sm ₂ O ₃ are seen. In the XRD image of Comparative Example 3, the peak of Sm ₂ Co ₁₇ is seen, but the peak of Co (b
cc & fcc), CoFe ₂ O ₄ and Sm ₂ O ₃ peaks are not observed.

Further, the hydrogen gas test sample was subjected to a hydrogen gas test under the same conditions as in Example 7 and then taken out.

Table 6 shows heat treatment conditions, presence or absence of resin coating, hydrogen gas test conditions, conditions after the hydrogen gas test, and Co and / or
Alternatively, the thickness of a layer (composite tissue layer) in which CoFe ₂ O ₄ and / or Sm ₂ O ₃ are finely present in Co or Fe is shown.
Examples 7 and 8 showed no change in the hydrogen gas test, whereas Comparative Example 3 was pulverized. From this, it is clear that Examples 7 and 8 did not cause hydrogen embrittlement.

[0077]

[Table 6]

Table 7 shows the magnetic properties of the magnet before and after the heat treatment and after the hydrogen gas test. After heat treatment and hydrogen gas test,
In Examples 7 and 8, there was almost no change in the magnetic characteristics. This indicates that in Examples 7 and 8, there was no deterioration in magnetic properties due to heat treatment and no hydrogen embrittlement. Comparative Example 3 was pulverized by the hydrogen treatment, so that the magnetic properties after the hydrogen treatment could not be measured.

[0079]

[Table 7]

Table 8 shows the heat treatment conditions, the presence or absence of resin coating, the hydrogen gas test conditions, and the state after the hydrogen gas test. Example 9 showed no change in the hydrogen gas test. From this, it is clear that Example 9 did not cause hydrogen embrittlement, indicating that the chipping was further prevented by resin coating and chipping was prevented.

[0081]

[Table 8]

[0082]

According to the present invention, it is possible to obtain a rare-earth sintered magnet which can be used for a motor or the like which does not cause hydrogen embrittlement for a long time even in a hydrogen atmosphere by the Sm ₂ Co ₁₇ based sintered magnet and the method for producing the same. Become.

[Brief description of the drawings]

FIG. 1 is a reflection electron image photograph of a magnet subjected to a heat treatment in a vacuum (oxygen partial pressure: 10 ⁻³ torr) at 400 ° C. for 2 hours in Example 1 using a scanning electron microscope.

FIG. 2 is a reflection electron image photograph of a magnet subjected to a heat treatment in vacuum (oxygen partial pressure: 10 ⁻³ torr) at 500 ° C. for 2 hours in Example 2 using a scanning electron microscope.

FIG. 3 is a backscattered electron image photograph of a magnet in Comparative Example 1 taken by a scanning electron microscope.

FIG. 4 is an XRD image of Example 1.

FIG. 5 is an XRD image of Example 2.

FIG. 6 is a backscattered electron image photograph of a magnet subjected to heat treatment in air at 500 ° C. for 2 hours in Example 7 using a scanning electron microscope.

FIG. 7 is a backscattered electron image photograph by a scanning electron microscope of a magnet subjected to heat treatment in air at 400 ° C. for 2 hours in Example 8.

FIG. 8 is a backscattered electron image photograph of a magnet in Comparative Example 3 taken by a scanning electron microscope.

FIG. 9 is an XRD image of Example 7.

FIG. 10 is an XRD image of Comparative Example 3.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Gen Nakamura, Inventor 2-1-5 Kitafu, Takefu-shi, Fukui Prefecture Shin-Etsu Chemical Co., Ltd. Magnetic Materials Research Laboratories (72) Takehisa Minowa 2-1 Kitafu, Takefu-shi, Fukui Prefecture 5 Shin-Etsu Chemical Co., Ltd. Magnetic Materials Research Laboratory F term (reference) 4K018 AA11 CA04 FA06 FA09 FA24 FA25 KA45 5E040 AA08 BD01 CA01 HB03 HB06 HB14 HB19 NN01 NN18 5E062 CD04 CF00

Claims (8)

[Claims] 1. R (where R is Sm or 50% by weight of Sm)
% Or more rare earth elements containing at least 20% by weight)
Fe10 to 45% by weight, Cu1 to 10% by weight, Zr0.
5 to 5% by weight, the balance consisting of Co and inevitable impurities
In a sintered earth magnet, the surface of the rare earth sintered magnet has C
o and / or Sm in Co and Fe _TwoO_ThreeAnd / or
CoFe_TwoO_FourCharacterized by having a composite tissue layer in which
Rare earth sintered magnet. 2. The rare earth sintered magnet according to claim 1, wherein the thickness of the composite structure layer on the surface of the rare earth sintered magnet is 0.1 μm or more and 3 mm or less. 3. The rare earth sintered magnet according to claim 1, wherein a resin coating film is formed on the composite structure layer. 4. The rare earth sintered magnet according to claim 3, wherein the thickness of the resin coating is 1 μm or more and 3 mm or less. 5. The rare earth sintered magnet according to claim 1, which has hydrogen resistance. 6. 20 to 30% by weight of R (where R is Sm or two or more rare earth elements containing 50% by weight or more of Sm)
Fe10 to 45% by weight, Cu1 to 10% by weight, Zr0.
An alloy consisting of 5 to 5% by weight, the balance being Co and unavoidable impurities, is cast, pulverized, then finely pulverized, molded in a magnetic field, sintered, and aged to form a sintered magnet, and the sintered magnet is further cut. And / or after polishing to finish the surface, under an atmosphere with an oxygen partial pressure of 10 ^{-6 to} 152 torr, for 10 minutes to
A method for producing a rare earth sintered magnet, which is heat-treated for 20 hours. 7. The method for producing a rare earth sintered magnet according to claim 6, wherein a resin coating is applied to the surface of the sintered magnet after the heat treatment. 8. The method for producing a rare earth sintered magnet according to claim 7, wherein the resin coating is spray coating, electrodeposition coating, powder coating or dipping coating.