JPH10270225A - Rare-earth bond magnet and manufacture therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rare-earth-Fe-Co bond magnet, having a magnetic property which is higher than that of the conventional magnet. SOLUTION: A rare-earth-Fe-Co bond magnet is manufactured by bonding the powder of a magnet alloy, having the composition of RaFebCocMd (where R and M respectively represents at least one kind of rare-earth element, including Y and at least one kind of element selected from among Al, Si, Ti, V, Cr, Ni, Zn, Cu, Ga, Zr, Nb, Mo, Hf, Ta, and W and a, b, c, and d represent wt.% respectively set at 12<=a<=40, the remaining wt.%, c<=50, and d<=10) and containing a total of 1-60 vol.% of α-Fe and α'-Fe-Co phases with a high molecular copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bonded magnet using a rare earth-iron-cobalt magnet alloy and a method for producing the same.

[0002]

2. Description of the Related Art Sm ₂ Co ₁₇ anisotropic bonded magnets have been put to practical use as bonded rare earth magnets.
R-Fe-B based isotropic bonded magnet by ultra-quenching method, HD
There is an R-Fe-B based anisotropic bonded magnet by the DR method. These are magnetic properties that are anisotropic and have an energy product of 20 MGOe or less and isotropic and 12 MGOe or less, but the production volume increases due to the characteristics of bonded magnets, such as complicated shapes and easy manufacturing into small articles. For example, it is frequently used in rotating machines such as spindle motors.

[0003]

The rare-earth bonded magnet has a lower magnetic property than the rare-earth sintered magnet, so that a further improvement is desired. There are magnet materials. The feature of this magnet material is an attempt to realize a magnet material having a high saturation magnetization and a high coercive force by combining a soft phase having a high saturation magnetization and a hard phase having a large anisotropic magnetic field. However, at present, Fe ₃ B—Nd ₂ Fe ₁₄ B system, α-Fe—Nd ₂ Fe
₁₄ B-based alloy system such α-Fe-SmFe ₇ Nx systems have been studied, but did not come to surpass the magnetic properties of the conventional rare earth bonded magnets. Accordingly, an object of the present invention is to provide a rare earth-iron-cobalt based bonded magnet having higher magnetic properties than the conventional one.

[0004]

As a measure for improving the magnetic characteristics of the exchange-coupled magnet material, the present inventor has studied as a soft magnetic phase a Fe-Co-based compound having the highest saturation magnetization other than nitride as a soft magnetic phase. The present inventors have conceived of using a combination with an Sm-Co compound having a high anisotropic magnetic field as a hard magnetic phase. The following production method was found as a means for producing a magnet material in which the Fe-Co-based and Sm-Co-based compounds were combined. First, in order to prepare an Fe—Co compound, for example, acicular Fe ₂ O ₃ or FeOOH having a particle diameter of 1 μm or less is used.
Alternatively, using Fe ₃ O ₄ as a raw material, CoO is epitaxially grown on the surface, and then this is grown in a stream of hydrogen.
By heating at 0 to 800 ° C., Fe and Co were reduced, and a Co film was formed on the surfaces of the α-Fe particles. Subsequently, the Sm metal is occluded with hydrogen and then pulverized to 10 μm or less, mixed at a predetermined ratio, and heated in a vacuum to cause Sm and Co to react to form an Sm-Co compound. At the same time, Co also reacts with Fe inside to form an Fe—Co compound having high saturation magnetization. This powder is molded in a magnetic field, and then 600-1000 in vacuum.
By heating at a temperature of ° C., the surface of the Fe—Co particles is completely covered with the Sm—Co-based compound. Subsequently, this powder is crushed to 1 mm or less to obtain the magnetic powder for an anisotropic bonded magnet of the present invention.

Namely, the present invention provides a composition formula R _a Fe _b C
o _c M _d (where, R represents at least one of rare earth elements including Y.) is represented by, 12 ≦ a ≦ 40wt%, b: balance, c ≦ 50wt%, d ≦ 10wt%, M is Al, S
i, Ti, V, Cr, Ni, Zn, Cu, Ga, Zr,
A magnetic alloy powder containing at least one of Nb, Mo, Hf, Ta, and W and having a total of 1 to 60 vol% of α-Fe phase and α'-Fe-Co phase in the structure is used. A rare earth bonded magnet characterized by being bound by a molecular polymer.

In the present invention, the rare earth element R is 12 wt%
As described above, the content is in the range of 40 wt% or less. As the rare earth element R, at least one of rare earth elements including Y can be used, but in order to increase the coercive force, Sm, Ce,
It is preferable to use at least one of Pr and Nd, and Sm is particularly preferable.

[0007] Co is necessary for the production of R-Co compounds,
It is an element that contributes to the improvement of corrosion resistance and thermal stability.
A range of t% or less is practical. In order to obtain a high residual magnetic flux density, the content is preferably set to 40 wt% or less.

The element M is an element effective for improving the coercive force, generating an R—Co-based compound, and suppressing the growth of crystal grains of the magnet alloy, and includes Al, Si, Ti, V, Cr, Ni, Zn,
It is at least one of Cu, Ga, Zr, Nb, Mo, Hf, Ta, and W. In particular, Cr is effective for improving the coercive force. Α-Fe phase and α'-Fe in the magnet alloy structure
It is easy to secure higher magnetic characteristics than in the past when the -Co phase is present at 1 to 60 vol% in total.

Next, the manufacturing method of the present invention will be described.
The Fe raw material is made of Fe ₂ O ₃ , FeOOH, or Fe ₃ O ₄ with CrO, MnO, CoO, NiO, ZnO, CuO
Use the one covered with etc. Of these, Co forms an R-Co-based compound, so the addition amount in the above range is necessary. The particles of FeOOH, Fe ₃ O ₄ , and Fe ₂ O ₃ are acicular and have a major axis diameter of 1 μm or less, preferably 0.5 μm or less. By heating such a Fe raw material in a hydrogen stream at 300 to 800 ° C., α-Fe is present at the center, and Cr, Mn, Co, Ni,
A powder covered with Zn, Cu, etc. is obtained. Co is R-Co
Cr, Mn, Ni, Z are essential to form a phase.
n, Cu, etc. are effective in improving the coercive force of the R-Co phase. On the other hand, metals such as Ce and Sm are used as rare earth materials, and Y, Pr, Nd, Gd, Tb, Dy, Ho, and Er are used as main materials.
And the like. A rare earth metal or a rare earth alloy containing them is placed in a hydrogen stream at 100
After heating to ８００800 ° C. to occlude hydrogen, the product is pulverized with a ball mill or a jet mill, etc.
m or less. Next, the Fe raw material and the rare earth raw material powder manufactured as described above are uniformly mixed at a predetermined ratio. At this time, Al, Si, Ti, V,
Cr, Ni, Zn, Cu, Ga, Zr, Nb, Mo, H
Add at least one powder of f, Ta and W.
Subsequently, this product is heated in a vacuum at 600 to 900 ° C.
-Generate a Co phase and diffuse a part of the Co into the α-Fe phase. In this state, the R-Co phase is α-Fe-Co
Since the phase is not completely covered, after further disintegration, the transverse magnetic field is formed, for example, with an applied magnetic field of 10 kOe or more. In the anisotropy imparting step, the so-called wet molding is performed by immersing the magnet alloy particles present in the powder or the molded body in a mineral oil having a high oxidation resistance imparting ability capable of suppressing an increase in the oxygen content, a synthetic oil, or the like. Is obtained. The obtained molded body is further placed in a vacuum at 600 to 100.
By heating at 0 ° C., a distinctive magnetic structure in which the major axis direction of the acicular α-Fe—Co phase is the magnetization direction, and the R—Co phase surrounds the periphery is obtained. This material is subsequently pulverized to a particle size of 0.5 mm or less and used as a raw material for a bonded magnet of the present invention.

When the bonded magnet of the present invention is manufactured by a compression molding method, for example, an epoxy resin is added as a thermosetting resin at 2 to 5% by weight as a thermosetting resin to the above bonded magnet raw material, and after homogenizing and mixing, a magnetic field is applied. Molding is performed in a medium or no magnetic field, and then a curing treatment is performed at a temperature of 100 to 200 ° C. to obtain a bonded magnet. In the case of injection molding, a bonded magnet can be obtained by molding in a magnetic field or without a magnetic field using an injection molding machine using a thermoplastic resin.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to examples. (Example 1) Needle-like particles in which CoO was formed on the surface of FeOOH particles were produced. The weight ratio of Co / (Fe + Co) was 0.3. The major axis diameter of the acicular particles was 0.1 μm. This was subjected to a reduction reaction in a hydrogen stream at 700 ° C. for 3 hours to obtain an Fe raw material. As a rare earth material, hydrogen was absorbed in a mixture of Ce metal (20 wt%) and Sm metal (80 wt%). Hydrogen storage was performed at 500 ° C. for 4 hours. Dissolve the hydrogen-absorbed material with a bantam mill,
It was pulverized with a jet mill. Samples 1 to 5 were prepared by mixing these Fe raw materials, rare earth raw materials, and additive powders at the ratios shown in Table 1. Next, each sample was placed in a vacuum at 800 ° C ×
The mixture was heated under the condition of 2 hours, crushed to 0.1 mm or less after cooling. This crushing is performed in a nitrogen atmosphere, and the crushed material is immersed in mineral oil (manufactured by Idemitsu Kosan Co., Ltd., trade name MC, OIL, P-02) to form a slurry, and then the slurry is applied to a predetermined mold while applying a magnetic field. Filling wet transverse magnetic field (applied magnetic field 1
The pressure was 2 kOe and the molding pressure was 2 t / cm ² ). Next, the obtained molded body was heated in vacuum at 200 ° C. for 8 hours to remove mineral oil, and further heated in vacuum for 870 × 2 hours. After cooling, the obtained product was crushed to 0.2 mm or less to obtain a raw material powder for a bonded magnet. A bond magnet was prepared by adding a solid epoxy resin (2 wt%) and acetone (2 wt%) to the raw material powder and thoroughly mixing with a Henschel mixer using an applied magnetic field of 18 kOe and a molding pressure of 6 t / cm ^2.
To form a transverse magnetic field. Subsequently, the obtained molded body is heated at 120 ° C. ×
The composition was cured for 1 hour at 180 ° C. × 1 hour to obtain a bonded magnet of the present invention having higher magnetic properties than the conventional one as shown in Table 1.

[0012]

[Table 1]

(Example 2) As shown in Table 2, on the surface of Fe ₂ O ₃ particles, CrO, MnO, NiO, Zn in addition to CoO
Samples 6 to 10 on which films of O and CuO were respectively formed were prepared. In each sample, the major axis diameter of the needle-like Fe ₂ O ₃ particles was 0.3.
1 μm and the weight ratio of Co / (Fe + Co) is 0.35. Each Fe raw material is heated at 760 ° C. for 3 hours in a hydrogen stream. Next, in each sample, Sm metal as a rare earth material was heated in a hydrogen stream at 500 ° C. for 4 hours to absorb hydrogen, and then ground to a particle size of about 5 μm using a ball mill. Next, the Fe raw material and the rare earth raw material were mixed at a ratio shown in Table 2, and immersed in toluene to form a slurry. These slurries were applied with an applied magnetic field of 12 kOe and a molding pressure of 1 t / c.
molded in a wet magnetic field under the conditions of m ^2, 200 ° C. The resulting molded body
The toluene was removed by heating in vacuum for 5 hours, and further heated in vacuum at 780 ° C for 2 hours to obtain the magnet alloy. Subsequently, this product was crushed to 0.05 mm or less, and further subjected to transverse magnetic field molding under the same conditions as in Example 1, and subsequently, the compact was heated in a vacuum at 850 ° C. for 2 hours. Next, it was pulverized with a bantam mill to 0.2 mm or less to obtain a raw material for a bonded magnet of the present invention. Thereafter, in the same manner as in Example 1, an anisotropic bonded magnet having higher magnetic properties than the conventional one shown in Table 2 was obtained.

[0014]

[Table 2]

(Example 3) The surface of Fe ₂ O ₃ particles was coated with CoO
Was formed. The major axis diameter of the obtained needle-like Fe ₂ O ₃ particles was 0.15 μm, and the weight ratio of Co / (Fe + Co) was 0.2. This was heated in a hydrogen stream at 760 ° C. for 3 hours. Rare earth material is Sm metal in hydrogen stream at 500 ℃
Heating was performed under conditions of × 4 hours to occlude hydrogen. After cooling,
It was pulverized with a ball mill to a particle size of about 5 μm. Thus, as shown in Table 3, samples 11 to 17 in which the above-mentioned Fe raw material, rare earth raw material and additives were mixed were prepared. Next, each sample was prepared using a synthetic oil (manufactured by Idemitsu Kosan, trade name DN, raw oil,
AL-35) to form a slurry. Each of the slurry raw materials was subjected to transverse magnetic field molding under an applied magnetic field of 12 kOe and a molding pressure of 1 t / cm ² , and heated in vacuum at 200 ° C. for 5 hours to remove synthetic oil, and further in vacuum at 800 ° C. for 2 hours. And heated. After cooling, the obtained one is 0.05 mm
It is crushed below, further molded in the transverse magnetic field in the same manner as in Example 1, and then heated in a vacuum at 870 ° C. × 2 hours and cooled, and then crushed into a 0.15 mm or less using a bantam mill to bond. It was used as a magnet material for magnets. (Α-Fe phase + α'-Fe-Co phase) in the obtained magnet powder for a bonded magnet,
Table 3 shows the measurement results of the amounts of SmCo ₅ phase, SmCo ₇ phase, and Sm ₂ Co ₁₇ phase generated. In Table 3, Fe
Co amount = (α-Fe phase + α′-Fe-Co phase) generation amount,
1/5 amount = SmCo ₅ phase generation amount, 1/7 amount = SmCo ₇
Phase generation amount, 2/17 amount = Sm ₂ Co ₁₇ phase generation amount.

[0016]

[Table 3]

(Α-Fe phase + α'-Fe-Co phase) is formed at the center of the magnet powder particles of each sample in Table 3.
It was found that the SmCo ₅ phase, the SmCo ₇ phase, the Sm ₂ Co ₁₇ phase, and the like surrounded the periphery. In addition, samples 11 to
The anisotropic bonded magnet manufactured in the same manner as in Example 1 using the 17 bonded magnet raw materials had higher magnetic properties than the conventional one.

[0018]

As described above, in the magnet material constituting the bonded magnet of the present invention, an R-Co compound is formed on the surface of needle-like Fe-Co particles, and the magnetization direction of the Fe-Co particles is aligned in the long axis direction. Thus, a useful bonded magnet having high saturation magnetization and high coercive force can be obtained.

Claims (8)

[Claims] 1. A composition formula in _{R a Fe b Co c M d} ( wherein, R
Is at least one of rare earth elements including Y. ), 12 ≦ a ≦ 40 wt%, b: balance, c ≦ 50 wt
%, D ≦ 10 wt%, M is Al, Si, Ti, V, C
r, Ni, Zn, Cu, Ga, Zr, Nb, Mo, H
f, Ta, W, and at least one of α-Fe phase and α'-Fe-Co phase in the structure.
A rare-earth bonded magnet, wherein a magnetic alloy powder having a vol% content is bound with a polymer. 2. The phase according to claim 1, wherein the α-Fe phase and / or α′-Fe—Co phase formed in the structure is acicular, and the major axis direction thereof substantially coincides with the magnetization direction. A rare-earth bonded magnet characterized by the following. 3. The magnet alloy powder particle according to claim 1, wherein an Fe—Co compound is formed on the inner center side of the magnetic alloy powder particles, and an R—Co compound is formed around the Fe—Co compound. Rare earth bonded magnets. 4. A composition formula _{R a Fe b Co c M d} ( where, R
Is at least one of rare earth elements including Y. ), 12 ≦ a ≦ 40 wt%, b: balance, c ≦ 50 wt
%, D ≦ 10 wt%, M is Al, Si, Ti, V, C
r, Ni, Zn, Cu, Ga, Zr, Nb, Mo, H
A method for manufacturing a rare earth bonded magnet in which a magnet alloy powder of at least one of f, Ta, and W is bound with a high molecular weight polymer, wherein a part of Fe is Cr, M
By reducing Fe ₂ O _{3 ,} FeOOH or Fe ₃ O ₄ substituted with at least one of n, Co, Ni, Zn and Cu at 300 to 800 ° C. in a hydrogen stream, fine α-F
e-particles, and the rare earth metal or rare earth alloy powder comprising R is reacted with the α-Fe particles to form a Fe—Co-based compound at the center of the magnet alloy powder particles. -A method for producing a rare earth bonded magnet, wherein the co-based compound has a structure morphology surrounded by the compound. 5. The method according to claim 4, wherein part of Fe is Cr,
The surface of Fe ₂ O ₃ , FeOOH or Fe ₃ O ₄ substituted with at least one of Mn, Co, Ni, Zn, and Cu is treated with at least one of CrO, MnO, CoO, NiO, ZnO, and CuO. A method for producing a rare earth bonded magnet, wherein the magnet is covered. 6. The method according to claim 4, wherein at least one of Al, Zn, Cu, and Ga oxides is added to a rare earth oxide and / or fluoride as a rare earth raw material of the magnet alloy. A method for producing a rare-earth bonded magnet, comprising using a rare-earth hydride formed by absorbing hydrogen after salt electrolysis. 7. The method according to claim 4, wherein the Fe raw material Fe ₂ O ₃ , FeOOH or Fe ₃ O ₄ has a major axis particle size of 1%.
A method for producing a rare-earth bonded magnet, wherein the magnet is needle-shaped having a diameter of not more than μm. 8. The composition formula _{R a Fe b Co c M d} ( where, R
Is at least one of rare earth elements including Y. ), 12 ≦ a ≦ 40 wt%, b: balance, c ≦ 50 wt
%, D ≦ 10 wt%, M is Al, Si, Ti, V, C
r, Ni, Zn, Cu, Ga, Zr, Nb, Mo, H
A method for manufacturing a rare earth bonded magnet in which a magnet alloy powder of at least one of f, Ta, and W is bound with a high molecular weight polymer, wherein a part of Fe is Cr, M
α- obtained by reducing Fe ₂ O _{3 ,} FeOOH or Fe ₃ O ₄ substituted with at least one of n, Co, Ni, Zn and Cu in a hydrogen stream at 300 to 800 ° C.
A small amount of at least one of Al, Zn, Cu, and Ga is added to a rare earth oxide and / or a fluoride as a rare earth raw material of the magnet alloy, and after electrolysis of molten salt, hydrogen is further absorbed. After reacting with the rare earth hydride thus formed to obtain the magnet alloy, the alloy powder is sintered in an organic solvent, mineral oil, or synthetic oil while imparting anisotropy in a retained state. And a method for producing a rare-earth bonded magnet.