JPH0776709A - Production of alloy powder containing rare earth metal - Google Patents

Abstract

PURPOSE:To produce alloy powder having extremely fine grain size by mixing the powder of rare earth metal oxides and the powder of alloy elements excluding rare earth metals with alkali metals and alkali metal chlorides and subjecting the same to direct reduction diffusing under specified conditions. CONSTITUTION:The powder of rare earth metal oxides, the powder of at least one kind of alloy element selected from Ni, Mn, Co, Al, Fe, Cu, Si, Mo, Cr, Zr, B, Nb, Ta, Ti, V, W, Sn and Ga, at least one kind selected from alkali metals, alkaline earth metals and their hydrates and at least one kind selected from alkali metal chlorides and alkaline earth metal chlorides are mixed. This mixture is heated to 900 to 1300 deg.C in an atmosphere of an inert gas or in a vacuum while being applied with 0.1kg/cm<2> compressing force and is thereafter cooled, and the obtd. reaction product is subjected to wet treatment.

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 an alloy powder containing a rare earth metal, and more specifically, a method for producing the alloy powder while suppressing the increase in grain size thereof as much as possible. Regarding

[0002]

2. Description of the Related Art An alloy containing a rare earth metal is known to be useful as a permanent magnet material, a hydrogen storage alloy material, a magneto-optical recording material, a magnetostrictive material, a magnetic refrigeration substance, a magnetic sensor and the like. Alloys containing such rare earth metals are often used in the form of alloy powder.

As a method of producing an alloy powder containing a rare earth metal, at least one selected from powders of rare earth metal oxides, powders of alloying elements other than rare earth metals, alkali metals, alkaline earth metals and hydrides thereof. The seed and at least one selected from alkali metal chlorides and alkaline earth metal chlorides are mixed, and the mixture is heated to 900 to 1300 ° C. in an inert gas atmosphere or under vacuum, and then cooled to obtain A so-called direct reduction diffusion method has been proposed in which the obtained reaction product mixture is wet-processed. This method has the advantage that the steps are relatively simple and low cost, and one of the reasons is that the coarse crushing step after the wet treatment step is unnecessary and the fine crushing step is also relatively small. Is.

[0004]

However, for the above method, it is further desired to reduce the load of the fine pulverization process.

In view of the above circumstances, an object of the present invention is to suppress the increase in particle size of the alloy powder containing a rare earth metal produced as much as possible in order to reduce the load of the fine pulverization process as much as possible. It is to provide a direct reduction diffusion method capable of

[0006]

In order to achieve the above object, the present invention provides a rare earth metal oxide powder, Ni,
Mn, Co, Al, Fe, Cu, Si, Mo, Cr, Z
at least one powder of M selected from r, B, Nb, Ta, Ti, V, W, Sn and Ga, and an alkali metal,
At least one selected from alkaline earth metals and hydrides thereof and at least one selected from alkali metal chlorides and alkaline earth metal chlorides are mixed, and the mixture is mixed in an inert gas atmosphere or under vacuum. 0.1 kg
900 ~ / cm ² while applying a compressive force of 900 ~
It is a method for producing an alloy powder containing a rare earth metal, which comprises heating to 1300 ° C., then cooling, and subjecting the obtained reaction product mixture to wet treatment.

[0007]

In the present invention, examples of rare earth metals include Gd, Tb, Ho, Er, Tm, Yb, La and C.
e, Pr, Nd, Sm, Eu, Lu, Pm, Y, Sc and the like can be mentioned, and these oxides can be used alone or in combination of two or more. The rare earth metal oxide powder preferably has an average particle size of 1 to 50 μm according to the Fisher subsieve sizer method (hereinafter, the average particle size means that according to this method).

As the alloying element other than the rare earth metal, at least one kind of the powder of M is used. The particle size of this powder is preferably 100 mesh or less.

At least one selected from alkali metals, alkaline earth metals and their hydrides, which is blended in the mixture, is used as a reducing agent, for example, Li,
Examples thereof include Na, K, Ca, Mg, and hydrides thereof. These are used in the form of particles or powder, and metallic calcium having a particle size of 4 mesh or less is preferable. Also,
At least one selected from an alkali metal chloride and an alkaline earth metal chloride suppresses fusion of the M powder and alloy powder particles generated by the direct reduction diffusion reaction with each other in the heating step, and suppresses grain growth. Has an effect. Therefore, in the wet treatment process, the reaction product mixture is easily disintegrated. Examples of these chlorides include chlorides such as Li, Na, K, Ca, and Mg, and anhydrides containing no hydrate are preferable. Further, anhydrous CaCl ₂ is particularly preferable because it exhibits almost no volatility when heated and is advantageous in terms of cost. The amount of these chlorides used is preferably 1 to 20% by weight with respect to the amount of rare earth metal oxide.

The above-mentioned raw materials are mixed, and the mixture is heated to 900 to 900 in an atmosphere of an inert gas such as argon or under vacuum.
A direct reduction diffusion reaction is performed by heating to 1300 ° C. If this is done under vacuum, the degree of vacuum is 10 ^-2.
More than torr is preferred.

In the present invention, it is extremely important to perform the above heating while applying a compressive force of 0.1 kg / cm ² or more to the mixture. By doing so, the above-mentioned action of suppressing the alloy powder particles from being fused and the particle growth of the alkali metal chloride and the alkaline earth metal chloride is significantly increased. It is considered that this is because the chloride melted by the above heating receives a compressive force and permeates and disperses a wider range between the particles in the mixture. In order to effectively exert such an action, the compressive force is 0.1 kg / c.
It is required to be m ² or more. However, if the compressive force is too high, the chloride tends to exude from the mixture and be wasted, and the amount of chloride contributing to the above action is rather decreased.

The mixture after heating is cooled, and the obtained reaction product mixture is subjected to wet treatment.

By the above, as compared with the alloy powder produced without applying compressive force during heating,
It is possible to produce alloy powders with significantly suppressed grain growth, that is to say with extremely fine grain sizes.

[0014]

【Example】

Example 1 72.6 g of Nd ₂ O ₃ powder having an average particle size of 3.3 μm (purity 99.9% by weight or more; hereinafter, wt% is referred to as%) and Dy ₂ O ₃ powder having an average particle size of 3.0 μm (purity 99. 9% or more)
Fe-B alloy (B: 1, 4.6 g, average particle size 5.2 μm)
9.1%) powder 17.3 g, average particle size 5.3 μm Fe
124.3 g of powder (purity of 99.5% or more), 40.8 g of metallic Ca having a particle size of 4 mesh or less (purity of 99% or more), and 7.7 g of anhydrous CaCl ₂ having a particle size of 100 mesh or less were sufficiently mixed. This mixture has an inner diameter of 8 cm and a height of 3
It is charged in a 0 cm cylindrical stainless steel reaction vessel, a stainless steel plate having a diameter of 7.8 cm and a thickness of 5 mm is placed on the mixture, and further 6.5 kg of stainless steel balls (diameter 4 to 50 mm). ) Was placed on a stainless steel container having a diameter of 7.5 cm and a height of 40 cm (compressed force applied was 0.15 kg / cm ² ). The inside of the reaction vessel was set to a high-purity Ar gas atmosphere, the temperature was raised to 980 ° C. in 70 minutes, the temperature was maintained for 3 hours, and then cooled to room temperature.

The resulting reaction product mixture was roughly crushed into a lump having a size of about 1 cm and then poured into 10 l of pure water, stirred for about 60 minutes and disintegrated in water to form a slurry. The white suspension of the upper layer containing Ca (OH) ₂ as the main component was separated from this slurry by decantation, and then water was poured again, and the slurry was stirred for 5 minutes and decanted.
This operation of water injection-stirring-decantation is repeated C
After sufficiently removing the component a, it was filtered. The obtained alloy powder is washed with ethanol, then at 40 ° C., 1 × 10 ⁻² t
Vacuum-dried at orr for 8 hours to obtain 192.1 g of alloy powder.

The composition of this alloy powder is Nd: 28.4.
%, Dy: 18.0%, B: 1.39%, Ca: 0.0
6%, oxygen: 0.18%, C: 0.022%, and the average particle size was 18.0 μm.

Comparative Example 1 A test was conducted in the same manner as in Example 1 except that the stainless steel weight was not placed on the mixture charged in the reaction vessel. The results are shown in Table 1.

Comparative Example 2 A test was conducted in the same manner as in Comparative Example 1 except that the amount of anhydrous CaCl ₂ blended was 16.0 g. The results are shown in Table 1.

Comparative Example 3 A stainless steel container having 3.0 kg of stainless steel balls (4 to 50 mm in diameter) placed on a stainless steel plate was placed (compressed force of 0.07 kg / cm ² ), except that The same test as in Example 1 was carried out. The results are shown in Table 1.

[0020]

[Table 1]

[0021]

According to the present invention, it is possible to produce an alloy powder containing a rare earth metal in which the increase in particle size is significantly suppressed by the direct reduction diffusion method.

Claims (1)

[Claims] 1. A rare earth metal oxide powder, and Ni, M
n, Co, Al, Fe, Cu, Si, Mo, Cr, Z
at least one powder of M selected from r, B, Nb, Ta, Ti, V, W, Sn and Ga, and an alkali metal,
At least one selected from alkaline earth metals and hydrides thereof and at least one selected from alkali metal chlorides and alkaline earth metal chlorides are mixed, and the mixture is mixed in an inert gas atmosphere or under vacuum. 0.1 kg
900 ~ / cm ² while applying a compressive force of 900 ~
A method for producing an alloy powder containing a rare earth metal, which comprises heating to 1300 ° C., then cooling, and subjecting the obtained reaction product mixture to wet treatment.