Method of producing rare earth magnetic powder and rare earth magnetic powder

Patent metadata

Field	Value
Publication number	US-2024062936-A1
Application number	US-202318448689-A
Country	US
Kind code	A1
Filing date	Aug 11, 2023
Priority date	Aug 17, 2022
Publication date	Feb 22, 2024
Grant date	—

Abstract

A method of producing a rare earth magnetic powder, the method including: heat-treating a mixture containing a SmFeN-based magnetic powder containing Sm, Fe, and N and a modifier powder containing Zn; and dispersing the heat-treated SmFeN-based magnetic powder using a resin-coated metal media or a resin-coated ceramic media.

First claim

What is claimed is:

1 . A method of producing a rare earth magnetic powder, the method comprising:
heat-treating a mixture comprising a SmFeN-based magnetic powder containing Sm, Fe, and N and a modifier powder containing Zn; and dispersing the heat-treated SmFeN-based magnetic powder using a resin-coated metal media or a resin-coated ceramic media.

2 . The method of producing a rare earth magnetic powder according to claim 1 ,
wherein the dispersing is performed in the absence of a solvent.

3 . The method of producing a rare earth magnetic powder according to claim 1 ,
wherein a specific gravity of the resin-coated metal media or the resin-coated ceramic media is not less than 4.

4 . The method of producing a rare earth magnetic powder according to claim 1 ,
wherein in the heat-treating, the mixture comprising the SmFeN-based magnetic powder and the modifier powder is heat-treated at a first temperature and then at a second temperature lower than the first temperature.

5 . The method of producing a rare earth magnetic powder according to claim 1 ,
wherein in the heat-treating, the SmFeN-based magnetic powder further contains La, W, and R, wherein R is at least one selected from the group consisting of Ti, Ba, and Sr.

6 . The method of producing a rare earth magnetic powder according to claim 5 , further comprising:
Pretreating by heat-treatment in a reducing-gas-containing atmosphere 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, to obtain a partial oxide; heat-treating the partial oxide 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 magnetic powder to be used in the heat-treating of the mixture comprising the SmFeN-based magnetic powder and the modifier powder containing Zn.

7 . A SmFeN-based rare earth magnetic powder, comprising Sm, Fe, and N,
wherein the SmFeN-based rare earth magnetic powder comprises at least 6% by mass but not more than 10% by mass of Zn based on a total amount of the rare earth magnetic powder, and wherein the SmFeN-based rare earth magnetic powder has a particle size D50 corresponding to a 50th percentile of a cumulative particle size distribution by volume of the SmFeN-based rare earth magnetic powder that is at least 1 μm but not more than 4 μm, a residual magnetization σr that is not less than 120 emu/g, and a squareness ratio Hk that is not less than 13000 Oe.

8 . The SmFeN-based rare earth magnetic powder according to claim 7 , having the squareness ratio Hk that is not less than 15000 Oe.

9 . The SmFeN-based rare earth magnetic powder according to claim 7 , further comprising La, W, and R, wherein R is at least one selected from the group consisting of Ti, Ba, and Sr.

10 . The SmFeN-based rare earth magnetic powder according to claim 7 , comprising:
a main phase containing Sm, Fe, and N; and a coating layer coating the main phase, wherein the coating layer contains Zn localized on a main phase side, and wherein the coating layer comprises a Zn-containing region and a P-containing region located outwardly from the Zn-containing region.

Assignees

• Nichia Corp
• Toyota Motor Co Ltd

Inventors

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

Classifications

• H01F1/059 Primary

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

• H01F1/0552

  with a protective layer · CPC title

• H01F1/0558

  bonded together · CPC title

• H01F41/0266

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

• H01F41/026

  protecting methods against environmental influences, e.g. oxygen, by surface treatment (magnetic particles with skin H01F1/061, H01F1/09, H01F1/24, H01F1/33 and G11B5/706) · CPC title