JPH04116101A - Magnetic powder for high-coercive-force anisotropic bond magnet and its production - Google Patents

Abstract

PURPOSE:To impart a high coercive force by forming an alloy powder consisting essentially of rare-earth elements, B, Fe, etc., added with a rare-earth oxide and having a specified particle diameter in a magnetic field, sintering and then crushing the formed body. CONSTITUTION:An alloy powder contg. 90-99wt.% of an alloy powder consisting essentially of 10-30 atomic% of a rare-earth element R (including Y), 2-28% B and 65-82% of M (>=1 kind among Fe, Co and Ni) and 1-10% of a rare-earth oxide consisting of >=1 kind among Nd2O3, Pr6O11, Dy2O3, Tb4O7 and Ho2O3 and with the average particle diameter adjusted to 0.5-50mum is formed in a magnetic field. The formed body is sintered at 900-1200 deg.C in a reducing or nonoxidizing atmosphere to obtain an anisotropic sintered magnet. The magnet is conventionally crushed into a magnetic powder having 20-500mum average particle diameter. The magnetic powder has a high coercive force, and an anisotropic bond magnet is provided with high productivity by using the powder.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is based on R (R is one of rare earth elements including yttrium), boron, M (M is Fe, Co.

The present invention relates to magnetic powder for use in anisotropic bonded magnets, which contains at least one type of Ni) as a main component and has excellent magnetic properties.

[Conventional technology]

Until now, magnetic powder for rare earth bonded magnets has been roughly divided into Sm
-Co-based and Nd-Fe-B-based magnetic powders have been proposed, but the former contains only atomic percent of the total rare earth metal insole, S
It has resource problems because it uses m and also contains a large amount of CO whose raw material supply is unstable. The latter is a permanent magnetic material that has been actively researched in recent years.
It is a permanent magnet material that does not contain expensive CO and is mainly composed of Nd, which is more abundant than Sm in terms of resources, and is attracting attention. The manufacturing method for Nd-Fe-B magnet powder that has been put into practical use so far is as typified by Japanese Patent Application Laid-Open No. 59-64739, in which molten alloy is made into an amorphous ribbon using a quenching ribbon manufacturing device, and then heat-treated. , is a method of obtaining magnetic powder by crushing. Furthermore, as disclosed in JP-A No. 60-100402, the method for manufacturing anisotropic magnetic powder by this method involves hot-pressing the above-mentioned isotropic magnetic powder into a molded body (this method involves molding the powder at a high temperature). 1. Anisotropic by deforming) ↓I, anisotropic magnetic powder for bonded magnets is obtained by pulverization.

[Invention or problem to be solved]

However, the above-mentioned quenching ribbon method (which yields highly anisotropic magnetic powder) requires hot pressing of isotropic magnetic powder and then upsetting at high temperatures, which is a complicated process. In addition, the method of obtaining magnetic powder by crushing an anisotropic sintered magnet using a powder metallurgy method has not only been pulverized, but also has the problem of large variations in quality. It has been found that the coercive force (iHc) decreases significantly, making it impractical for practical use.

[Means to solve the problem]

The present invention solves the problems of the prior art as described above,
An object of the present invention is to provide magnetic powder for anisotropic bonded magnets having high magnetic properties and a method for manufacturing the same.

That is, the first aspect of the present invention is that R (wherein R is at least one rare earth element including isotria): lO to 30 atomic %, B (boron): 2 to 28 atomic %, M (however, M is F
at least one of e, Co, and Ni): 65-8
An average particle diameter of 20 to 500, consisting of 90 to 99 weight % of an alloy mainly containing 2 atomic % and 1 to 10 weight % of a rare earth oxide.
μm high coercive force type anisotropic bonded magnet magnetic powder, and the second aspect of the present invention is R (where R is at least one rare earth element including yttrium): 1O to 30 at%, boron = 2
~28 atomic%, M (where M is at least one of Fe, Co, and Ni): 90 to 99% by weight of alloy fine powder whose main component is 65 to 82 atomic%, and Nd2O5, Pr5O
i+, 'DY*Os, Tb40t', HO20! Rare earth oxides consisting of at least one of the following: 1-1O
Average particle size 0.5-50μm with a composition including weight%
A high coercive force type alloy powder is produced, which consists of one step of compacting the alloy powder in a magnetic field and sintering it at 900 to 1200°C in a reducing or non-oxidizing atmosphere, and one step of crushing it to an average particle size of 20 to 500 μm after sintering. The content is a method of manufacturing magnetic powder for oriented bonded magnets.

The rare earth element (R) in the present invention is ythtrium (Y)
One or more rare earth elements including neodymium (Nd
), praseodymium (Pr), lanthanum (La).

Cerium (Ce), samarium (Sm), gadolinium (Gd), promedium (Pm), europium (Eu)
), lutetium (Lu), and the like. Isn't yttrium (Y) a rare earth element? In the present invention, it can be treated in the same way as other rare earth elements. If the rare earth element (R) content is less than 10 atomic %, the coercive force (iHc) will be low, and if it is 30 atomic % or more, the residual magnetic flux density (Br) will be low, making it impossible to obtain a high-performance magnet. Further, if the B content is less than 2 atomic %, the coercive force will be low, and if it is 28 atomic % or more, the residual magnetic flux density will be low.

Furthermore, the rare earth oxides in the present invention include Nd2O5, P
r5O++, llY2O3+, Tb4O7,HO'
Dy202.203 is an example, preferably Dy202. Tb4
0□ can exhibit high magnetic performance. The composition of the present invention is composed of the above-mentioned R-Fe-B alloy and rare earth oxide, or if the amount of rare earth oxide added is less than 1% by weight, high coercive force cannot be obtained; As a result, the residual magnetic flux density decreases, and it cannot be used as a high-performance magnetic material. If the average particle diameter of the magnetic powder after pulverization is smaller than 20 μm, the coercive force will be significantly reduced and the performance as a permanent magnet will not be satisfactory. If it is 500 μm or more, the dimensional accuracy will be reduced when formed into a bonded magnet. , there are problems with surface smoothness, making it impractical. Furthermore, the average particle diameter of the rare earth oxide is 0.
If it is less than 51 μm, the sintered density will decrease, and 10
If it is larger than μm, the main phase is rare earth, for example Nd2F.
It does not diffuse uniformly into the e+J+ phase.

In the present invention, a generally known powder metallurgy method can be used for manufacturing the anisotropic sintered magnet before pulverization. That is, after pulverizing a melted and cast alloy of a predetermined composition, a molded body is produced using a magnetic field press, and the molded body is sintered at a temperature of 900 to 1200°C in a vacuum state of 102 Torr or more or in Ar gas to perform anisotropic sintering. Can you get a magnet? Furthermore, the sintered magnet can be pulverized by a normal mechanical pulverization method or a hydrogen occlusion method in which the sintered magnet absorbs hydrogen and disintegrates. In the mechanical pulverization method, it is preferable to pulverize in an inert gas or an organic solvent in order to prevent rapid oxidation of the magnetic powder during pulverization. Furthermore, in order to obtain magnetic powder with higher performance, the magnetic powder after pulverization must be heated at 500 to 1000 in an inert gas or under a high vacuum of 10-2 Torr or higher.
By performing heat treatment at a temperature of °C, it is possible to particularly improve the coercive force.

The mechanism by which the pound magnet according to the present invention exhibits excellent performance will be explained by taking as an example the case where an alloy powder containing an alloy mainly composed of Nd, Fe, and B and an alloy powder containing Dy2Q3, which is a rare earth oxide, is used. That is, when an anisotropic sintered magnet is produced by mixing rare earth oxides, especially heavy rare earth oxides, as in the present invention, during sintering, reduction is caused by the rare earth oxides or Nd appearing as a liquid phase. The main phase is Nd2F.
The Nd site of the e l 4 B + phase is replaced, and the anisotropy field value is greatly improved.

Instead, oxidized Nd is unevenly distributed in the grain boundaries around the main phase, or because this oxidized Nd phase is a mechanically fragile phase, it is preferentially and easily destroyed during pulverization, minimizing the destruction of the main phase. It becomes possible to crush the powder. Due to the above-described mechanism, the magnetic powder after pulverization has a high coercive force, and it is thought that it can be used as a high-performance magnetic powder for bonded magnets.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained with reference to examples, but the present invention is not limited to these in any way.

Examples 1-3 As starting materials, Nd: 15 at%, Fe nia: 7 at%.

B: An alloy whose composition was adjusted to 8 atomic % was produced by arc melting. 50 ~ by the obtained alloy stamp mill
Dy20 coarsely ground to 500 μm and with an average particle size of 1 μm
s were mixed at the mixing ratio shown in Table 1, and pulverized together with ethanol in a ball mill. The obtained finely pulverized powder was press-molded in a magnetic field of 20 kOe, and then molded in Ar gas at a temperature of 1080'C for 1 hour in a vacuum.
Sintering was performed for several hours, and after sintering, it was rapidly cooled to room temperature. Thereafter, heat treatment was performed at 700° C. for 12 hours in Ar to obtain an anisotropic sintered magnet.

The obtained anisotropic sintered magnet is stamped by a stamp mill for 50~
The powder was pulverized to a particle size range of 300 μm, and then an epoxy resin was mixed so that the magnetic powder content was 97% by weight to obtain a bonded magnet mixture. Subsequently, these mixtures were press-molded in a magnetic field of 20 kOe to obtain an anisotropic bonded magnet according to the present invention.

The magnetic properties of the obtained pound magnet are shown in Table 1.

Example 4 A rare earth oxide is Tb4O7 with an average particle size of 1 μm,
An anisotropic bonded magnet was obtained in the same manner as in Example 1 except that the mixing ratio was 5% by weight. The results are shown in Table 1.

Example 5 Anisotropic magnetic powder produced using the same composition and manufacturing method as Example 2 was heat-treated in Ar gas at 700°C for 1 hour, and then rapidly cooled to room temperature to obtain heat-treated magnetic powder.

An anisotropic bonded magnet was produced using this magnetic powder in the same manner as in Example 2. The results are shown in Table 1.

Comparative Example 1 An anisotropic bonded magnet was produced in the same manner as in Example except that the rare earth oxide was not added.

The results are shown in Table 1.

Comparative Example 2 In Example 1, the alloy composition was changed to Nd: 12 atomic %, Dy:
Adjusted to 3 at%, Fe 7 at%, B: 8 at%,
An anisotropic bonded magnet was produced in the same manner as in Example 1 except that the composition did not include the addition of rare earth oxides. Results first
Shown in the table.

As shown in the data of Examples 1 to 3 shown in Table 1, the coercive force improves as the amount of Dy20a added increases, and that of Comparative Example 1. It was found that a bonded magnet having extremely superior magnetic properties compared to No. 2 could be obtained. It was also found that a bonded magnet having a high coercive force could be obtained even in Example 4 using Tb40□ as the rare earth oxide. Furthermore, as shown in the data of Example 5, it can be seen that further improvement in coercive force can be expected by applying heat treatment.

Compared to these, Comparative Example 1 in which no rare earth oxide was added. 2, the coercive force was only at an extremely low level.

〔Effect of the invention〕

As detailed above, according to the present invention, it is possible to produce magnetic powder for anisotropic bonded magnets having a high coercive force, and it is possible to provide anisotropic bonded magnets using such magnetic powder with good productivity. can do.

Table 1

Claims (5)

[Claims] (1) R (where R is at least one rare earth element including yttrium): 10 to 30 atomic%, boron: 2 to 2
Alloy 9 whose main component is 8 atomic %, M (where M is at least one of Fe, Co, and Ni): 65 to 82 atomic %
Magnetic powder for a high coercive force type anisotropic bonded magnet having an average particle diameter of 20 to 500 μm and consisting of 0 to 99% by weight and 1 to 10% by weight of rare earth oxide. (2) Rare earth oxides are Nd_2O_3, Pr_6O_1
_1, Dy_2O_3, Tb_4O_7, Ho_2O_
The magnetic powder for a high coercive force type anisotropic bonded magnet according to claim 1, characterized in that the magnetic powder contains at least one kind of the following. (3) R (where R is at least one rare earth element including yttrium): 10 to 30 atomic%, boron: 2 to 2
8 atomic%, M (where M is at least one of Fe, Co, and Ni): 90 to 99% by weight of alloy fine powder whose main component is 65 to 82 atomic%, and Nd_2O_3, Pr_6O_
1_1, Dy_2O_3, Tb_4O_7, Ho_2O
Rare earth oxide 1 consisting of at least one of _3
Average particle size 0.5-5 with a composition containing ~10% by weight
A high coercive force type anisotropic process consisting of a step of compacting 0 μm alloy powder in a magnetic field, sintering it at 900 to 1200°C in a reducing or non-oxidizing atmosphere, and pulverizing it to an average particle size of 20 to 500 μm after sintering. A method for producing magnetic powder for bonded magnets. (4) The method for producing magnetic powder for a high coercivity type anisotropic bonded magnet according to claim 3, wherein the average particle diameter of the rare earth oxide is 0.5 to 10 μm. (5) The anisotropic magnetic powder obtained by pulverization is heated to 500 to 500 m
The method for producing magnetic powder for a high coercive force type anisotropic bonded magnet according to claim 3, wherein the magnetic powder is heat-treated at a temperature of 1000°C.