SmFeN BASED RARE EARTH MAGNET AND PRODUCTION METHOD THEREOF

Patent metadata

Field	Value
Publication number	US-2024161975-A1
Application number	US-202318506354-A
Country	US
Kind code	A1
Filing date	Nov 10, 2023
Priority date	Nov 10, 2022
Publication date	May 16, 2024
Grant date	—

Abstract

A method of producing a SmFeN-based rare earth magnet, the method including: heat-treating a SmFeN-based anisotropic magnetic powder having a surface coated with a phosphate at a temperature of at least 80° C. but lower than 150° C.; mixing the heat-treated SmFeN-based anisotropic magnetic powder and a Zn-containing modifier powder by dispersion using resin-coated metal media or resin-coated ceramic media to obtain a powder mixture containing the SmFeN-based anisotropic magnetic powder and the modifier powder; compacting the powder mixture in a magnetic field to obtain a magnetic field compact; and pressure-sintering the magnetic field compact to obtain a sintered compact.

First claim

What is claimed is:

1 . A method of producing a SmFeN-based rare earth magnet, the method comprising:
heat-treating a SmFeN-based anisotropic magnetic powder having a surface coated with a phosphate at a temperature of at least 80° C. but lower than 150° C.; mixing the heat-treated SmFeN-based anisotropic magnetic powder and a Zn-containing modifier powder by dispersion using resin-coated metal media or resin-coated ceramic media to obtain a powder mixture containing the SmFeN-based anisotropic magnetic powder and the modifier powder; compacting the powder mixture in a magnetic field to obtain a magnetic field compact; and pressure-sintering the magnetic field compact to obtain a sintered compact.

2 . The method of producing a SmFeN-based rare earth magnet according to claim 1 , further comprising, before the heat-treating:
acid-treating the SmFeN-based anisotropic magnetic powder to be used in the heat-treating with an acid to obtain an acid-treated SmFeN-based anisotropic magnetic powder, and phosphate-source-treating the acid-treated SmFeN-based anisotropic magnetic powder with a phosphate source to obtain the SmFeN-based anisotropic magnetic powder having the surface coated with the phosphate.

3 . The method of producing a SmFeN-based rare earth magnet according to claim 1 ,
wherein in the mixing, the dispersion is performed in a dry condition.

4 . The method of producing a SmFeN-based rare earth magnet according to claim 1 ,
wherein the resin-coated metal media or the resin-coated ceramic media have a specific gravity of at least 4.

5 . The method of producing a SmFeN-based rare earth magnet according to claim 1 ,
wherein the heat-treated SmFeN-based anisotropic magnetic powder includes a first particle group and a second particle group, and the first particle group has a particle size D 50 at 50% of a cumulative particle size distribution by volume that is larger than a particle size D 50 at 50% of a cumulative particle size distribution by volume of the second particle group.

6 . The method of producing a SmFeN-based rare earth magnet according to claim 1 ,
wherein the SmFeN-based anisotropic magnetic powder comprises La, W, and R, wherein R is at least one selected from the group consisting of Ti, Ba, and Sr.

7 . The method of producing a SmFeN-based rare earth magnet according to claim 6 , further comprising:
pretreating an oxide containing Sm, Fe, La, W, and R, wherein R is at least one selected from the group consisting of Ti, Ba, and Sr, by heat treatment in a reducing-gas-containing atmosphere to obtain a partial oxide; reducing the partial oxide by heat treatment in the presence of a reducing agent to obtain alloy particles; nitriding the alloy particles to obtain a nitride; and washing the nitride to obtain the SmFeN-based anisotropic magnetic powder to be used in the heat-treating.

8 . The method of producing a SmFeN-based rare earth magnet according to claim 1 , further comprising
heat-treating the sintered compact to obtain a SmFeN-based rare earth magnet.

9 . A SmFeN-based rare earth magnet, comprising:
a SmFeN-based anisotropic magnetic powder; and a coating portion coating the SmFeN-based anisotropic magnetic powder, the coating portion comprising an outer peripheral region in which P is localized, and an inner region located inward from the outer peripheral region, in which Zn is localized.

Assignees

• Nichia Corp
• Toyota Motor Co Ltd

Inventors

• Maehara Hisashi
• Inuzuka Tomonori
• Ito Masaaki
• Hiraoka Motoki

Classifications

• H01F1/059

  and Va elements, e.g. Sm2Fe17N2 · CPC title

• H01F41/0266 Primary

  Moulding; Pressing (H01F41/0273 takes precedence; hard magnetic particles H01F1/06, H01F1/11) · CPC title

• B22F1/052

  characterised by a mixture of particles of different sizes or by the particle size distribution · CPC title

• B22F1/142

  Thermal or thermo-mechanical treatment · CPC title

• B22F1/145

  Chemical treatment, e.g. passivation or decarburisation · CPC title