JPH04221005A - Production of rare-earth metal-containing alloy powder by reductive diffusion - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 vibration load 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

[0008] In addition, the conventional reduction-diffusion method only yields products with an average crystal grain size of 10 μm or more, making it difficult to use it as a raw material powder for resin-bonded magnets that are expected to have high performance. Ta.

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.

0010

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventors have developed a method for solving the above-mentioned problems by using a mixture of Ca metal powder, rare earth oxide powder, and metal raw material powder.
Heat treatment is performed under an inert gas or vacuum atmosphere while applying vibrations of ,000 Hz, and the reaction product generated at this time is wet-processed to remove by-produced CaO and Ca remaining in the reaction product. When producing alloy powder containing rare earth metals using the reduction diffusion method by removing
The inventors have discovered that raw material powder suitable for use as raw material powder for resin-bonded magnets can be obtained, leading to the present invention.

[0011]

[Operation] In the present invention, 50 to 25
The reason why heat treatment is performed in an inert gas or vacuum atmosphere while applying vibrations of 50 to 25,000 Hz is to construct a heated body by applying heat treatment to a metal raw material while applying vibrations of 50 to 25,000 Hz. In addition to making it possible to easily obtain raw material powder that suppresses crystal growth and is composed of ultrafine crystal grains that are suitable for use as raw material powder for resin-bonded magnets, the alloying element after heating the raw material mixture can be easily obtained. This is to also improve the diffusion reaction ability of the molecule.

0012

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.

The mixture obtained here was placed in a stainless steel container and subjected to heat treatment at 1000° C. for 4 hours under an argon gas atmosphere while applying vibration at 50 Hz.
After that, the reaction product is cooled and disintegrated by throwing it into pure water, followed by repeated stirring and decantation until the hydrogen ion concentration becomes 8 or less, and finally, when the water is removed and dried, Approximately 95g of alloy powder was recovered.

The composition of this alloy powder is 33.0% by weight of Nd, 65.5% by weight of Fe, 1.3% by weight of B, and 0.2% by weight of O. It was observed that the crystals constituting this alloy powder had an average grain size of 1.3 μm.

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
When a bonded magnet was produced by molding while applying a pressure of 2.0 mL, the coercive force of the obtained magnet was 5.8 KOe.

Example 2 When the same procedure as in Example 1 was carried out except that the load vibration during heating of the mixture was 70 Hz, the coercive force of the obtained magnet was 5.9 KOe.

[0017] The composition of the obtained raw material powder is as follows: Nd is 33
．． 2% by weight, Fe is 65.3% by weight, B is 1.3% by weight, O is 0.2% by weight, and the crystals constituting this alloy powder have an average diameter of 1.2 μm. It was observed that the grain size was shown.

Example 3 When the same procedure as in Example 1 was carried out except that the load vibration during heating of the mixture was 100 Hz, the coercive force of the obtained magnet was 6.0 KOe.

[0019] The composition of the obtained raw material powder is such that Nd is 32
．． 8% by weight, Fe is 65.7% by weight, B is 1.3% by weight, O is 0.2% by weight, and the crystals constituting this alloy powder have an average diameter of 1.2 μm. It was observed that the grain size was shown.

Example 4 When the same procedure as in Example 1 was carried out except that the load vibration during heating of the mixture was 20,000 Hz, the coercive force of the obtained magnet was 5.8 KOe.

[0021] The composition of the obtained raw material powder is as follows: Nd is 33
．． 0% by weight, Fe is 65.5% by weight, B is 1.3% by weight, O is 0.2% by weight, and the crystals constituting this alloy powder have an average diameter of 1.4 μm. It was observed that the grain size was shown.

Example 5 When the same procedure as in Example 1 was carried out except that the load vibration during heating of the mixture was 22,000 Hz, the coercive force of the obtained magnet was 6.0 KOe.

[0023] The composition of the obtained raw material powder is such that Nd is 32
．． 9% by weight, Fe is 65.6% by weight, B is 1.3% by weight, O is 0.2% by weight, and the crystals constituting this alloy powder have an average diameter of 1.3 μm. It was observed that the grain size was shown.

Example 6 When the same procedure as in Example 1 was carried out except that the load vibration during heating of the mixture was 25,000 Hz, the coercive force of the obtained magnet was 5.9 KOe.

[0025] The composition of the obtained raw material powder is such that Nd is 32
．． 9% by weight, Fe is 65.7% by weight, B is 1.2% by weight, O is 0.2% by weight, and the crystals constituting this alloy powder have an average diameter of 1.6 μm. It was observed that the grain size was shown.

Comparative Example 1 Except that no special load vibration was applied when heating the mixture,
When all treatments were carried out in the same manner as in Example 1, the coercive force of the obtained magnet was only 0.5 KOe.

[0027] The composition of the obtained raw material powder is as follows: Nd is 33
．． 1% by weight, Fe is 65.4% by weight, B is 1.3% by weight, O is 0.2% by weight, and the crystals constituting this alloy powder have an average diameter of 8.5 μm. It was observed that the grain size was shown.

As described above, according to the present invention, all of the crystals constituting the raw material powder for producing the magnet alloy exhibit an average crystal grain size of 5.0 μm or less, which is necessary to improve the performance of the resin magnet. This has been recognized, and it has become possible to significantly improve the coercive force of resin magnets manufactured using this raw material powder.

[0029] When applying vibration to the mixture when carrying out the present invention, in the case of applying vibration of 20,000 Hz or more, use SONIFIER Model manufactured by BRANSON.
-450, and vibrations of 50 to 100 Hz were applied using a vibration generator including a 120 W AC motor equipped with a speed reducer and a vibrator.

The crystal grain size of the product of the present invention was measured using an image analysis analyzer (model CIS-1) manufactured by GALAI.

The above measurement results are shown in Table 1 below.

[0032]

[Table 1]

[0033]

Effects of the Invention According to the present invention, it has been found that all of the crystals constituting the raw material powder used in the production of magnet alloys exhibit a fine average crystal grain size of 5.0 μm or less. It has become possible to significantly improve the degree of orientation of magnetic properties when manufacturing materials with high precision.
It has become possible to supply the product economically and in a stable manner, and this will greatly contribute to the industry, which has been hoping for such a situation.

Claims (1)

[Claims] Claim 1: A mixture consisting of metallic Ca powder, rare earth oxide powder, and metal raw material powder is subjected to heat treatment in an inert gas or vacuum atmosphere while applying vibration, and the reaction generated at this time is By wet-processing the product, CaO produced as a by-product and Ca remaining in the reaction product are removed, and then the above reaction product is pulverized to produce alloy powder containing rare earth metals. A method for producing alloy powder containing rare earth metals using a reduction diffusion method, characterized by: