JPH04224608A - Manufacture of alloy powder containing rare earth metal using reduction diffusing method - Google Patents

Abstract

PURPOSE:To offer a method for obtaining magnetic alloy powder contg. rare earth metals excellent in magnetic properties by using a reduction diffusing method. CONSTITUTION:A mixture of metallic Ca powder, rare earth oxide powder and metallic raw material powder is applied with stress and is molded, and this mixture molded body is subjected to heating treatment in the atmosphere of an inert gas or vacuum. CaO by-produced at this time and Ca remaining in a reaction product are removed to obtain metallic grains, which are pulverized to manufacture alloy powder contg. rare earth metals.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for producing alloy powder containing rare earth metals using a reduction-diffusion method under stress conditions.

0002

BACKGROUND OF THE INVENTION Due to their excellent magnetic properties, alloy magnets containing rare earth metals are used in a wide range of fields, from home appliances to communications, audio equipment, medical equipment, and general industrial equipment.

[0003] A method for producing such alloy powder containing rare earth metals by a reduction diffusion method is known.

That is, in this method, first, a mixture consisting of a metal Ca powder, a rare earth oxide powder, and a metal raw material powder is heated in an inert gas or vacuum atmosphere to convert the rare earth oxide into a rare earth metal. At the same time, the generated rare earth metal is diffused into other metal particles forming a part of the alloy components to obtain an alloy powder with a desired composition.

[0005] In this case, unnecessary substances such as oxides of the residual metal contained in the reaction product obtained by heating the mixture or produced as a by-product by the reaction with the residual metal Ca are removed from the reaction product. It is removed from the reaction product by carrying out a wet process in which the product is poured into water after cooling and, if necessary, the product is washed with acid.

[0006] This method allows the use of relatively inexpensive oxides as raw materials for rare earth metals, eliminates the need for a melting and casting process, and provides highly disintegrable lumpy reaction products, making it easy to produce alloy powder with the desired particle size. It is considered to be an excellent method from various aspects, such as the fact that it can be obtained easily.

[0007]

[Problems to be Solved by the Invention] Although the reduction diffusion method is considered to be an excellent method from various aspects as described above, it is necessary to use raw materials that are not in powder form as iron raw materials, such as foils, needles, etc. When using raw materials such as shaped bodies, thin bodies, plate bodies, etc., the degree of contact between these iron raw materials and other raw material powders deteriorates, and the diffusion of alloying elements deteriorates, resulting in However, the problem arises that it is difficult to obtain an alloy with a desired composition, and the crystal grains of the obtained alloy rarely grow in a fixed direction, resulting in a problem with the magnetic orientation of the manufactured magnet. It was difficult to strengthen the

In view of the above circumstances, the present invention improves the degree of contact between the iron raw material and other raw material powders in the use of the reduction diffusion method, and also allows the crystal grains of the obtained alloy to grow in a fixed direction. The purpose is to improve the magnetic properties of products by manipulating them in such a way as to direct the magnetic properties of the product.

[0009]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides Ca metal powder, rare earth oxide powder,
1t/cm2 for a mixture consisting of metal raw material powder
After molding with the above stress applied, this mixture molded body is heat-treated in an inert gas or vacuum atmosphere, and the reaction products generated at this time are wet-treated, and the by-produced C
This paper presents a method for producing alloy powder containing rare earth metals using a reduction diffusion method by removing aO and Ca remaining in the reaction product.

0010

[Operation] In the present invention, 1 t/cm2 for the mixture
After molding with the above stress applied, the mixture molded body is subjected to heat treatment in an inert gas or vacuum atmosphere. Later, by applying heat treatment to this mixture molded body, the growth direction of the crystals constituting the heat-treated body grows preferentially in the direction perpendicular to the direction that is easily magnetized, and the magnetic properties are particularly improved in a certain direction. This is to make it easier to obtain stronger alloy powder, and to also improve the diffusion reaction of alloying elements after heating the raw material mixture.

[0011]

EXAMPLES Example 1 The present invention will be explained in detail in the following examples. That is, 65.6 g of electrolytic iron powder with a purity of 99.9% by weight and an average particle size of 200 mesh (according to Tyler standards), and 42.3 g of neodymium oxide powder with a purity of 99.9% by weight and an average particle size of 325 mesh (according to Tyler standards). and purity 99.9% by weight,
1.3 g of pure boron powder with an average particle size of 325 mesh (according to Tyler standard) and granular metal Ca2 with a purity of 99% by weight
3 g using a V-blender.

[0012] The mixture obtained here was placed in a stainless steel container and molded under a pressure of 2.0 t/cm2, and then the molded mixture was heated for 100 min in an argon gas atmosphere.
Heat treatment was performed at 0°C for 4 hours, after which the reaction product was cooled and disintegrated by being thrown into pure water, followed by repeated stirring and decantation until the hydrogen ion concentration became 8 or less. When the moisture is finally removed and dried,
Approximately 95g of alloy powder was recovered.

The composition of this alloy powder is 32.6% by weight of Nd, 65.8% by weight of Fe, 1.4% by weight of B, and 0.2% by weight of O. It was observed that all the crystals constituting this alloy powder were oriented in a certain direction.

This alloy powder was pulverized using a vibrating disk mill, and 0.3 g of epoxy resin and 0.1 g of a hardening agent were mixed with 20 g of the obtained raw material powder with an average particle size of less than 325 mesh. , 4.1t/cm in a magnetic field of 15kOe
A bonded magnet was manufactured by molding while applying a pressure of 2.

In this case, the residual magnetic flux density of the obtained magnet was 11.9 KG, and the degree of magnetic orientation was 49%.

Example 2 When the process was carried out in the same manner as in Example 1 except that the applied stress during pressure molding of the mixture was 4.0 t/cm2, the residual magnetic flux density of the obtained magnet was 12.1 KG. The degree of magnetic orientation was 55%.

[0017] The composition of the obtained raw material powder is as follows: Nd is 33
．． 0% by weight, Fe was 65.5% by weight, B was 1.3% by weight, and O was 0.2% by weight.

Example 3 When the process was carried out in the same manner as in Example 1 except that the applied stress during pressure molding of the mixture was 6.0 t/cm2, the residual magnetic flux density of the obtained magnet was 12.2 KG. The degree of magnetic orientation was 58%.

[0019] The composition of the obtained raw material powder is as follows: Nd is 33
．． 2% by weight, Fe was 65.3% by weight, B was 1.3% by weight, and O was 0.2% by weight.

Comparative Example 1 When the process was carried out in the same manner as in Example 1 except that the applied stress during pressure molding of the mixture was 0.5 t/cm2, the residual magnetic flux density of the obtained magnet was 10.2 KG. However, the degree of magnetic orientation was only 3%.

[0021] The composition of the obtained raw material powder is as follows: Nd is 33
．． 3% by weight, Fe was 65.3% by weight, B was 1.2% by weight, and O was 0.2% by weight.

Comparative Example 2 When all treatments were carried out in the same manner as in Example 1 except that the applied stress during pressure molding of the mixture was 0 t/cm2, the residual magnetic flux density of the obtained magnet was 10.1 KG, The degree of magnetic orientation was only 1%.

[0023] The composition of the obtained raw material powder is as follows: Nd is 33
．． 0% by weight, Fe was 65.5% by weight, B was 1.3% by weight, and O was 0.2% by weight.

Table 1 shows the magnetic properties and alloy powder compositions of Examples 1 to 3 and Comparative Examples 1 and 2.

As shown in Table 1, according to the present invention, since all of the crystals constituting the raw material powder are grown in the same direction when producing a magnet alloy, the degree of orientation of the magnetic properties is improved when producing a magnet. It has become possible to significantly improve the

In measuring the degree of orientation of the product of the present invention, a lens with a magnification of 10 times is used for both the eyepiece lens and the objective lens of the polarizing microscope, and after taking a photograph, the field of view of the photograph is Select 100 crystal grains from among them,
For each crystal grain, calculate the product of the cosine value of the angle with the specific direction and the occupied area, divide the total product value by the total area of the crystal grains targeted for measurement, and then multiply this value by 100. The obtained result was expressed as the degree of orientation.

[0027]

[Table 1]

[0028]

[Effects of the Invention] According to the present invention, since all of the crystals constituting the raw material powder are grown in the same direction when manufacturing a magnet alloy, the degree of orientation of magnetic properties can be greatly improved when manufacturing a magnet. Since it has become possible to improve the quality of materials, it has become possible to supply highly accurate materials economically and in a stable manner, and this will greatly contribute to the industry, which has been hoping for such a situation to emerge. There is something.

Claims (1)

[Claims] Claim 1: A mixture consisting of metallic Ca powder, rare earth oxide powder, and metal raw material powder is molded by applying a stress of 1 t/cm2 or more, and then the molded mixture is heated in an inert gas or vacuum. Heat treatment is performed in an atmosphere, and the reaction products generated at this time are wet-treated to remove CaO as a by-product.
A method for producing an alloy powder containing a rare earth metal using a reduction diffusion method, characterized in that an alloy containing a rare earth metal is produced by removing Ca remaining in the reaction product.