JPS60106905A - Production of permanent magnet alloy powder - Google Patents

Abstract

PURPOSE:To obtain a product contg. remaining Ca and C in a smaller amt. and having an excellent magnetic characteristic and stability with a direct reduction diffusion method for the permanent magnet alloy powder consisting of a Cu substd. type multi-element rare earth intermetallic compd. by using an acid for cleaning the resultant product of reduction diffusion reaction. CONSTITUTION:The permanent magnet alloy powder of the compsn. expressed by the formula (R is >=1 kind among rare earth metals including mainly Sm, Ce and Pr, M is >=1 kind among Si, Ti, Zr, Mn, V, Nb, Cr, Mo, Hf, 0.01<=x<=0.40, 0.02<=y<=0.25, 0.001<=z<=0.15, 5.0<=A<=8.0) is produced by a reduction diffusion method with rare earth oxide as a raw material. The resultant product of the reduction diffusion reaction is cleaned in an acidic aq. soln. having 2-5pH and is then neutralized by washing and dried. The dried product is subjected to wet pulverizing to form the powder which has 2-5mu average grain size and of which the contents of Ca and C as impurities during pulverization are maintained respectively at <=0.2wt%.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a Cu@ exchange type multi-component rare earth intermetallic compound permanent magnet alloy.

Conventionally, 5i1Ti was added to the alloy system R-Go -Fe-Cu.
It is known that excellent magnetic properties can be obtained by adding transition metal elements such as , Zr, Mn, Cr, and H (such as It has been reported that characteristics with an energy product of 30 MGQe or more can be obtained.

(For example, see Japanese Patent Publication No. 55-50100.) In order to obtain such high characteristics, a part of the CO)"e SCu
.

M(Si, -ri, Zr, Mn, V,, NiMo.

It is a well-known fact that substitution with (1-1r, etc.) is an essential condition.

The method for producing such a multi-component rare earth intermetallic compound permanent magnetic alloy is to use rare earth metals, cobalt, iron, and other alloy constituents as pure metals (#1. Close to pure metals) as raw materials. The most common method is to crush the cast ingot after frequency melting. However, rare earth metals are generally expensive, and the melting method requires high raw material costs, which increases manufacturing costs.

On the other hand, as a method to improve the above-mentioned drawbacks of the dissolution method, a reducing agent (Ca 2 ) is used using an inexpensive rare earth oxide as a raw material.

A direct reduction-diffusion method is known in which CaH2, M (+, etc.) is used to reduce the material and alloy it with cobalt, iron, and other alloy components through a diffusion reaction. (For example, Tokuko Sho 49-729
6, No. 53-16798, No. 55-30575, and No. 55-27602) However, the problem with the direct reduction diffusion method is that the magnetic properties are inferior to those using the conventional high-frequency dissolution method. There was a point. The reason is as follows.

In the conventional direct reduction diffusion method, rare earth oxides and metal powders or oxides of other constituent elements are converted into Ca SCa H
2. From the reaction product obtained by reduction and diffusion with MO etc., impurities CaO, 1vloO are converted to Ca(OH)2
, tVlg (OH)2, Ca(OH)2,
A common method is to discharge Mll (Ol-1)2 by repeatedly washing it with water (decantation).

However, Ca(OH)2, M(J(Of-1)2
Both are poorly soluble compounds, and their separation requires a large amount of water and labor, resulting in loss of production. Moreover,
The magnet alloy powder separated and collected in this way usually contains 0.2 wt% or more of Ca and C as impurities, so permanent magnets made by powder metallurgy using this magnet alloy powder as materials are , the residual magnetic flux density (Br) decreases due to residual CaO, and the residual C decreases M (Si, Ichikawa, Zr, ,Nb
Since carbides are formed with 1Cr, MO, Hf, etc. or Sl), the substantially effective weight ratio in the magnet alloy decreases, resulting in a decrease in coercive force. On the other hand, in order to prevent this decrease in coercive force, the coercive force can be restored to the desired value by adding an excessive amount of M element to the target composition in advance or by adding an excessive amount of Qu. It is possible. However, even with such means, a slight decrease in 3r due to carbides and oxides cannot be avoided, so although magnetic properties close to those obtained by the melting method can be obtained, residual ca, cai
Due to the variations in magnetic properties, the magnetic properties have a disadvantage that they vary more than those produced by the melting method.

The present invention improves the above-mentioned drawbacks of the conventional direct reduction-diffusion method, and provides carbon fiber with excellent magnetic properties, stability, and production efficiency.
It is an object of the present invention to provide a manufacturing method capable of obtaining LI-substituted multi-component rare earth intermetallic compound permanent magnet alloy powder.

The method for producing the permanent magnet alloy powder of the present invention is to mix a rare earth oxide with a metal powder such as Fe or Go SM, or a part or all of the oxide, at a temperature range of Iooo to 1300'C, preferably under argon gas. After carrying out a reduction-diffusion reaction in a reducing atmosphere containing hydrogen gas, the reaction product is pickled in an acidic aqueous solution with a pH of 2 to 5, neutralized by washing with water, and the resulting alloy powder is dry-pulverized. The present invention will be explained in more detail below.

Reduction by-product CaO produced by direct reduction diffusion method
Ca Co 3 has a solubility in water of 0.13 g each.
CaO/ 100111 (20℃), 1.4i g
Ca C.

According to conventional decantation by washing with water, the reduction reaction by-products ca o, ca cO
In step 3, decantation, CaO, which is sparingly soluble in water, is pickled in an acidic aqueous solution with a pH of 2 to 5 in advance.
Ca Co 3 to Ca cl 2, Ca (cto13C
oo) Convert to a calcium salt with high solubility in water such as 2. After that, by decantation by washing with water and adjusting the pH to 6 to 8, the amount of impurities Ca and C in the dried permanent magnet alloy powder can be easily reduced to 0.
．． It becomes possible to control the weight to 2% or less.

Furthermore, when turning the alloy powder thus obtained into a permanent magnet by powder metallurgy as a raw material, it is necessary to pulverize the alloy powder by a wet or dry method, but in the present invention, this pulverization step is The process is characterized by dry pulverization, preferably jet mill pulverization, in an inert gas atmosphere. The reason why dry pulverization is an essential component of the present invention is as follows.

When finely pulverizing the alloy powder according to the present invention using a wet ball mill, vibration mill, attritor, etc., toluene, acetone, etc. Grinding is typically carried out in grinding media.

However, when wet pulverization is performed in a medium such as toluene or acetone, the medium and rare earth metal powder react through mechanochemical reaction during pulverization, and C in the medium adsorbs and reacts with the surface of the alloy powder. If the amount of C is increased, or in extreme cases, carbides such as Ss C + Ti C and Zr C are formed during pulverization, which deteriorates the magnetic properties after sintering. However, in the case of alloy powder produced by the melting method, the amount of C before the powder is usually 0.
．． Since it is less than 1wt%, even if the C content increases slightly due to wet pulverization, the amount of C after pulverization will not exceed 0.2WL%, and therefore the effect on magnetic properties is small, and wet pulverization is possible. On the other hand, in alloy powder produced by the reduction diffusion method, 0.2% by weight is usually added to the powder after pulverization.
As mentioned above, even if the cleaning method according to the present invention is used, normally 0
．． Since C is contained in an amount of 0.8 to 0.2% by weight or more, an increase in the amount of C due to a mechanochemical reaction during pulverization has a non-negligible effect on the final magnetic properties.

Therefore, the present invention is characterized in that the impurity CI after pulverization is controlled to 0.2% or less by using a dry ball mill, dry attritor, jet mill, etc. for fine pulverization. Among dry pulverization methods, jet mill pulverization using Ar, N2, etc. is particularly effective.By performing jet mill pulverization, it is possible to reduce the Ca content and C content compared to before fine pulverization, and Caff1 can be reduced. 0.15 weight.

m% or less, and it is also possible to make the C content 0.1% by weight or less. The reason for this is that when the rare earth metal permanent magnet alloy powder containing CaO1CaCO3 is pulverized by a jet mill, it is separated in a cyclone due to the difference in specific gravity, resulting in impurities with small specific gravity such as ca o and ca c.

3 is because it is concentrated to the filter side.

The present invention will be explained in detail below.

Example 1 Final target composition: 311125.4 wt%, Co 49.
8wt%, Cu7.5wt%, Fe15.0wt%,
5ill 203,C so that Hf2.3wt%
a 1Fe% Cos Cu SHf powder was weighed and mixed for 30 minutes in a V-type mixer, and the resulting raw material powder was
In an iron reaction vessel, a reduction-diffusion reaction was carried out in H2 gas at 1200°C for 3 hours to obtain a reaction cake of about 20 kg.
After mixing with a stirrer for one hour, washing with water was repeated for 5 hours, and after confirming that the pH of the water was 10 or less, it was dried and the impurity amount of Ca was poured into a washing bucket filled with water. and the amount of C was analyzed.

The other sample (Sample B) was poured into a washing bucket filled with approximately 30α water, the acidic aqueous solution was discharged, and the sample was washed several times with water and then dried.

When CI was analyzed, as shown in Table 1, in sample B, the amount of 'ca and c was less than 0.2% by weight, whereas in sample B, it was 0.2% by weight or less. Residual Ca and Cff1 of more than % by weight were observed.

Example 2 A portion of the magnetic alloy powder obtained in Example 1 was pulverized for 4 hours in a dry ball mill in an N2 atmosphere while the jacket was being heated with water. The average particle size after pulverization was approximately 4 μ for both samples A and B.

The finely pulverized powder thus obtained was placed in a magnetic field with 2FON/
It was molded at a molding pressure of am2. The obtained molded body was heated to 119
After performing post-sintering heat treatment in vacuum at 0°C for 2 hours, the magnetic properties were measured. As shown in Table 2, sample B had a lower residual magnetic flux density and coercive force than sample A. New characteristics were obtained.

Table 2 Example 3 1 ko of the sample 1 pAB obtained in Example 1 was pulverized in toluene for 3 hours using a wet vibration mill, and the average particle size was 3.3 μm.
I tried it as nc. On the other hand, another 1 kill of sample B, N
The powder was finely pulverized using a jet mill in two gases to obtain a sample with an average particle size of 3.1 μm.

When analyzing the impurities ca and cm in sample final and D, as shown in Table 3, in sample C and J3, Cm increased compared to before pulverization, but in sample C, Ca, cm increased.
-C also decreased in Cff1 compared to before pulverization.

These finely pulverized powders were molded, sintered, and
After applying heat treatment and measuring and comparing the magnetic properties, it was found that the fourth
As shown in the table, a higher coercive force was obtained in the C sample than in the C sample.

As described above, according to the present invention, a multi-component rare earth magnet alloy powder containing few impurities can be easily manufactured in a timely manner.

In this example, 8l-CO-Fe-Cu-
Although the Hr system has been described, the present invention is not limited to the scope of this example.

Claims (1)

[Claims] 1, R(GO+ -X-y-ZFeXCLIyMZ
) A (Here, R is one type or a combination of two or more rare earth metals centered on 5IIIl and Ce1Pr, and M is 5i1T+ SZ+' 1M1l , V, Nb
, a combination of one or more of Cr, Mo, Hf, 0.01≦X≦0.40. , 0,02≦y≦0
．． 25, o, ooi≦l≦0.15.5.0≦A≦8.
In the method of producing a permanent magnet alloy powder having the composition shown in 0) by a reduction diffusion method using a rare earth oxide as a starting material, the reduction diffusion reaction product is washed in an acidic aqueous solution with a pH of 2 to 5, and then washed with water and dried. It is characterized by dry pulverization to give an average particle size of 2 to 5μ, and the amount of impurity Ca during pulverization being 0.2% by weight or less and impurity C being 0.2% by weight or less. A method for producing magnet alloy powder. 2. Cam during pulverization is 0.15% by weight or less and CI
2. A method for producing a permanent magnet alloy powder according to claim 1, wherein: 0.2% or less.