JPH06158122A - Production of rare-earth magnet fine powder - Google Patents

Abstract

PURPOSE:To produce a rare-earth magnet fine powder of specified composition excellent in magnetic characteristic at low cost by allowing a precipitant to act on a soln. contg. rare-earth elements, Fe, Co, Ni and B and reducing the precipitated fine powder. CONSTITUTION:A soln. contg. the salts or organmetallic compds. of Re (rare- earth elements including Y), the salts or organometallic compds. of Fe, Co and Ni and the org. compd. of B, as required. A precipitant is allowed to act on the soln. to precipitate the fine powder. The fine powder is mixed with Ca powder, and the mixture is heat-treated in a nonoxidizing atmosphere and reduced. Consequently, a rare-earth magnet fine powder shown by Re3Ti100-a-bBb (5<=a<=30mol% and 0<=b<=15%) and having 0.01-10mum particle diameter is obtained. The magnet fine powder is obtained with no need for crushing, the generation of a magnetic impurity phase based on crystal distortion is suppressed, and the magnetic characteristic is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing fine powders of rare earth magnets suitable as materials for sintered magnets and bonded magnets.

[0002]

2. Description of the Related Art In recent years, fine powders of rare earth magnets have greatly expanded in response to the tendency of electronic devices to become thinner, thinner and smaller. The rare earth magnet material powders that have been developed so far are roughly classified into two types, Sm-Co system and Nd-Fe-B system.

A conventional method for producing a rare earth magnet fine powder will be described below. First of all, the Sm-Co system was carried out by a method in which an ingot having a desired composition was produced in a high-frequency melting furnace or the like, and then the ingot was crushed, molded and sintered, and then crushed again.

Next is the Nd-Fe-B system, which contains S
As in the case of the m-Co system, a method of crushing a sintered body and a method of making a molten alloy into an amorphous ribbon by a quenching ribbon manufacturing apparatus, followed by heat treatment and crushing have been performed.
In particular, regarding the method using an amorphous ribbon, a method has also been used in which after the magnetic powder is formed into a compact by hot pressing, an anisotropic bulk magnet is obtained by plastically deforming at high temperature and crushing this.

[0005]

However, in each of the above-mentioned prior arts, the step of pulverization is indispensable, so that the obtained magnet fine powder has a lot of crystal strain due to pulverization, and these act as magnetic impurities. Therefore, there is a problem that desired magnetic characteristics cannot be obtained.

The present invention solves the above-mentioned conventional problems. Fine powder is taken out as a precipitate from a solution system containing necessary elements, and further reduced and alloyed, so that magnetic impurities due to crystal strain are almost found. An object of the present invention is to provide a method for producing a rare earth magnet fine powder that cannot be used.

[0007]

In order to achieve this object, the method for producing the rare earth magnet fine powder of the present invention comprises the following three items. At least one salt or organometallic compound of a rare earth element containing Y and at least one salt or organometallic compound of Fe, Co, Ni, or Y
A solution system comprising at least one salt of a rare earth element or an organometallic compound containing, a salt of Fe, Co, Ni or at least one organometallic compound, and an organic compound of B is prepared, A method for producing a rare earth magnet fine powder, in which a fine precipitation powder is precipitated by causing a precipitation agent to act on, and the fine precipitation powder is reduced to obtain a magnet fine powder having a composition represented by the following general formula. General formula Re _a T _100-ab B _{b where} Re is at least one of rare earth elements including Y
Seed, T is at least one or more of Fe, Co, and Ni, and a and b are mol percentages of 5 ≦ a ≦ 30 and 0 ≦ b ≦ 1.
5 The method for producing the rare earth magnet fine powder as described above, wherein the particle diameter of the rare earth magnet fine powder is 0.01 to 10 μm. The method for producing a rare earth magnet fine powder as described above or the above, wherein the precipitated fine powder is mixed with Ca powder and heat-treated in a non-oxidizing atmosphere to reduce the fine powder.

[0008]

With this structure, it is possible to provide a method for producing a rare earth magnet fine powder having a small amount of magnetic impurity phase due to crystal strain.

[0009]

EXAMPLES The details of the present invention will be described below based on examples. The technique of producing magnet fine powder as a precipitate from a solution system containing necessary elements, which is an essential item in the present invention, has been a conventional problem because it is possible to omit the pulverizing step because the magnet fine powder is directly produced. The magnetic impurity phase due to crystal strain can be reduced to a level at which it is hardly seen.

Next, an example of producing rare earth magnet fine powder by using the production method of this embodiment will be described. (Example 1) Sm (O-iso- C 3 H 7) 3, Co
(O-iso-C ₃ H ₇ ) ₂ was added to Sm _17.1 Co, respectively.
_A uniform solution was prepared by dissolving the solute in an amount corresponding to the fine powder composition shown by _82.9 in dry iso-C ₃ H ₇ OH so that the total amount of the solutes was 2 mol / l (liter). Next, while taking out 500 ml of each solution and maintaining each at 80 ° C., a solution prepared by diluting distilled water 10 times with iso-C ₃ H ₇ OH was added in an amount of 1.5 equivalents necessary for hydrolysis of each system, and the mixture was left as it was The mixture was stirred at 80 ° C for 12 hours. The precipitate formed was taken out by centrifugation, mixed with Ca powder, and kept at 700 ° C. for 4 hours in an Ar atmosphere to reduce the alloy powder. Then, after removing the CaO powder, an appropriate heat treatment was performed to obtain a rare earth magnet fine powder having a particle diameter of about 500 nm.

As a comparative example, fine powder having a composition represented by Sm _17.1 Co _82.9 was prepared by a conventional method including a pulverizing step. That is, an amount of Sm and Co corresponding to the fine powder composition was melted and alloyed in a high frequency melting furnace. The obtained alloy was crushed with a hammer mill to obtain a green compact, which was sintered, further subjected to an appropriate heat treatment and then pulverized again to be classified to 53 to 106 μm to obtain a rare earth magnet fine powder.

The magnetic powder content of the obtained magnetic powder, a binder resin obtained by diluting a mixture of bisphenol A type epoxy resin and phenol novolac with methyl ethyl ketone was 97.
The mixture was mixed at a weight percentage, and methyl ethyl ketone was evaporated while stirring the mixture to obtain a blend before molding. The characteristics of the isotropic bonded magnet obtained by press-molding such a blend at a molding pressure of 5 t / cm ² are shown in (Table 1).

Example 2 SmCl ₃ .6H ₂ O, Co
Cl ₂ .6H ₂ O was dissolved in distilled water in an amount corresponding to the fine powder composition represented by Sm _17.1 Co _82.9 in distilled water so that the total amount of solutes was 2 mol / l, to prepare a uniform solution. Next, take out 500 ml of each solution and each at 80 ℃.
While maintaining at 0.1 mol / l, an aqueous NaOH solution of 0.1 mol / l was added in an amount of 1.5 equivalents necessary for the hydrolysis of each system, and 8
The mixture was stirred at 0 ° C for 12 hours. After removing the generated precipitate by centrifugation, it is mixed with Ca powder and 700
The alloy powder was reduced by holding it at 4 ° C for 4 hours. Then, after removing the CaO powder, an appropriate heat treatment was performed to obtain a rare earth magnet fine powder having a particle diameter of about 500 nm.

The magnetic powder content of the obtained magnetic powder, a binder resin obtained by diluting a mixture of bisphenol A type epoxy resin and phenol novolac with methyl ethyl ketone was 97.
The mixture was mixed at a weight percentage, and methyl ethyl ketone was evaporated while stirring the mixture to obtain a blend before molding. The characteristics of the isotropic bonded magnet obtained by press-molding such a blend at a molding pressure of 5 t / cm ² are shown in "Table 1".

[0015]

[Table 1]

As is apparent from "Table 1", according to the method for producing the rare earth magnet fine powder of this embodiment, a magnetic impurity phase due to crystal strain caused by pulverization is hardly seen as desired. It is possible to obtain excellent magnetic specific rare earth magnet fine powder and bonded magnet, which can be reduced to a level.

In the above examples, salts or organic metal compounds such as rare earth elements are chlorides and isopropoxides, but other inorganic salts such as sulfates can be used, and industrially inexpensive raw materials can be selected and used. can do. As the organic metal compound, other alkoxides and β-diketonate salts such as acetylacetonate salts can be used. In addition, it is preferable to use an alkoxide as a raw material in that impurities such as by-products are unlikely to be mixed.

The usual solvent can be freely selected. Distilled water is used when the raw material is salt, alcohol, ether, tetrahydroxyfuran,
Dimethylformamide and dimethylsulfoxide are preferred. When an alkoxide is used as a raw material, the corresponding alcohol is more preferable from the viewpoint of solubility. Since the concentration of the solution is a factor that affects the particle size of the fine powder to be precipitated, it is possible to select a concentration that gives a desired size. Higher concentrations are preferred to obtain finer particle sizes.

As the precipitant, any substance capable of depositing fine powder can be used. In addition to precipitation by nucleophilic substitution of alkoxide with water as in this Example, or precipitation by reacting metal ion with hydroxide ion, oxalate ion, phosphate ion, borate ion For example, it may be precipitated as a sparingly soluble salt by adding such a compound, or may be precipitated as a hydroxide or sulfide by blowing in ammonia or hydrogen sulfide. Further, it is within the scope of the present invention to use a plurality of the precipitants used in the present invention at the same time. Furthermore, when two or more types of precipitants are used, a plurality of types can be added at the same time, or can be added sequentially with a time interval. By selecting the charging method in this way, particles with a layered structure of multiple metal species can be prepared,
It can be said that particles having a uniform phase can be prepared, and the advantage of using a plurality of types of precipitants.
However, although the layer structure may be suitable in some cases in terms of magnetic properties, it may not be suitable in some cases. In that case, it is necessary to perform mutual diffusion treatment between a plurality of metal species by heating or the like.

Although it is a reduction of fine powder, a conventional Ca reduction can be used. As the atmosphere during the reduction, in addition to Ar, an inert atmosphere such as vacuum or nitrogen, or a reducing atmosphere such as hydrogen, ammonia, ammonia + hydrogen, or ammonia + carbon monoxide can be used. It is preferable to perform the treatment in a reducing atmosphere in order to increase the reduction efficiency.

The rare earth element Re in the present invention is at least one kind of rare earth element containing Y, and is Nd, Pr, La or C.
e, Sm, Gd, Pm, Eu, Lu, Dy, Tb, Ho
Can be exemplified. Although Y is not a rare earth element, it can be treated in the same manner as other rare earth elements in the present invention. The preferred rare earth element Re in the present invention is mainly composed of Nd or Sm, but may contain misch metal, didymium, or other rare earth elements which are complex rare earth elements.

In the present invention, additional elements may be added to improve the magnetic properties. As the additive element, Al, Si, Ti, V, Cr, Mn, Cu, Zn,
Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, H
Examples thereof include f, Ta, W, Pb, Bi and C, which can be added to the solution as a salt or an organometallic compound. One or more of these additive elements may be added for the purpose of improving various characteristics such as Br, iHc, and prismatic columns.

The particle size of the magnet fine powder obtained in the present invention is preferably 0.01 to 10 μm. In a conventional method including pulverization, if it is attempted to pulverize up to this level, it becomes over-pulverized and becomes impractical as a magnet, but it is known that the magnetic properties are improved as the production method according to the present invention approaches this level. Considering handling, it is more preferably 0.1 to 1 μm.

The magnet powder obtained in the present invention can be used as a bonded magnet hardened with a binder or a sintered magnet obtained by sintering. In the above embodiment, the binder was synthetic resin, but Z
It may be a low melting point alloy such as n or Bi. Needless to say, when used as a magnetic powder for a bonded magnet, the surface of the magnetic powder may be treated with a silane-based or titanate-based coupling agent.

Further, after producing a sintered magnet, a bonded magnet, etc., resin coating, metal plating, etc. can be applied.

[0026]

As described above in detail, according to the present invention,
In rare earth magnet fine powder, it is possible to improve the magnetic properties, and since the raw material is lower in price and the number of steps is smaller than the conventional method, the manufacturing cost can be suppressed, so it can be said that the industrial value is extremely high. .

Claims (3)

[Claims] 1. A rare earth element containing at least one of a salt or an organometallic compound of a rare earth element containing Y and at least one of a salt or an organometallic compound of Fe, Co, Ni, or a rare earth element containing Y. A solution system comprising at least one of a salt or an organometallic compound, at least one of a salt of Fe, Co, Ni or an organometallic compound, and an organic compound of B is prepared, and a precipitating agent acts on the solution. A method for producing a rare earth magnet fine powder, in which the fine precipitate powder is deposited to reduce the precipitate fine powder to obtain a magnet fine powder having a composition represented by the following general formula. General formula Re _a T _100-ab B _{b where} Re is at least one of rare earth elements including Y
Seed, T is at least one or more of Fe, Co, and Ni, and a and b are mol percentages of 5 ≦ a ≦ 30 and 0 ≦ b ≦ 1.
5 2. The particle diameter of the rare earth magnet fine powder is 0.01
The method for producing a fine powder of rare earth magnet according to claim 1, wherein the fine powder has a diameter of 10 μm. 3. The reduction method according to claim 1, wherein the precipitated fine powder is mixed with Ca powder and heat-treated in a non-oxidizing atmosphere.
A method for producing the rare earth magnet fine powder described.