Method of manufacturing rare-earth magnet powder, and method of manufacturing rare-earth bond magnet

Abstract

A method of manufacturing rare-earth magnet powder having excellent magnetic properties, and a method of manufacturing a rare-earth bond magnet are provided. A nitriding step is performed, in which when nitrided rare-earth magnet powder is produced, rare-earth-element / transition metal-based alloy powder is irradiated with a microwave at an atmosphere containing nitrogen atoms, so that the nitrogen atoms are allowed to enter into a crystal lattice.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a method of manufacturing rare-earth magnet powder, and a method of manufacturing a rare-earth bond magnet.[0003]2. Description of the Related Art[0004]Recently, much attention has been paid on a rare-earth magnet as a magnet having excellent magnetic properties. Among various magnet materials for the rare-earth magnet, a magnet produced by nitriding SmFe alloy or the like (hereinafter, called nitride compound magnet) is particularly focused with attention as a magnet material having high Curie point and excellent magnetic anisotropy.[0005]Method of manufacturing a nitride compound magnet having a rare earth element as a main component typically has steps of alloy melting, crushing, nitriding, press forming, sintering, machining, magnetization and the like. Typically, in nitriding, alloy powder is subjected to heating under a gas atmosphere of N2, NH3 or the like, or a mixed gas atmosphe...

AI Technical Summary

Benefits of technology

The invention relates to a method for manufacturing rare-earth magnet powder with improved magnetic properties. The method involves irradiating rare-earth-element / transition metal-based alloy powder with microwaves to allow nitrogen atoms to enter the crystal lattice. After nitriding, the powder is heated in an inert gas to form a homogenized structure. The microwave irradiation has a frequency of 1 GHz to -30 GHz to allow for uniform nitriding and prevent excessive nitriding. The grain diameter of the alloy powder is controlled to prevent oxidation and excessive nitriding. The atmosphere pressure during nitriding is controlled to prevent the formation of an amorphous state. The rare-earth magnet powder can be mixed with a resin binder or a metal binder for molding. The technical effects of the invention include reduced processing time, uniform nitriding, and improved magnetic properties of the rare-earth magnet powder.

Problems solved by technology

However, in a method of performing heating at high pressure as the method described in JP-A-5-109518 or JP-A-5-135978, there is a problem that nitriding is inadequate, so that a region being not nitrided is formed in a rare-earth-element / transition metal-based magnet material, consequently the magnetic material is nonuniformly nitrided.

As a result, nitriding easily proceeds only in a particular portion of the rare-earth-element / transition metal-based magnet material, resulting in nonuniform nitriding.

Moreover, when hydrogen is remained in a magnet, the magnet becomes gradually significantly brittle in a long-term use condition, which is not preferable.

However, in this case, processing time is increased and thus production efficiency is reduced, in addition, cost is extremely increased.

Moreover, even if the nitrogen gas is substituted or evacuated, oxygen is hard to be perfectly removed from the inside of the alloy powder.

In this way, each of the methods has various problems, and each value of magnetic properties of the rare-earth-element / transition metal-based magnet nitrided by each method is still considerably low compared with a theoretical value at present.

Images