Method of producing SmFeN-based rare earth magnet

Patent metadata

Field	Value
Publication number	US-12027306-B2
Application number	US-202217806300-A
Country	US
Kind code	B2
Filing date	Jun 10, 2022
Priority date	Jun 10, 2021
Publication date	Jul 2, 2024
Grant date	Jul 2, 2024

Abstract

A method of producing a SmFeN-based rare earth magnet, the method including: dispersing a SmFeN-based anisotropic magnetic powder comprising Sm, Fe, and N using a resin-coated metal media or a resin-coated ceramic media to obtain a dispersed SmFeN-based anisotropic magnetic powder; mixing the dispersed SmFeN-based anisotropic magnetic powder with a modifier powder to obtain a powder mixture; compacting the powder mixture in a magnetic field to obtain a magnetic field compact; pressure-sintering the magnetic field compact to obtain a sintered compact; and heat treating the sintered compact.

First claim

What is claimed is:

1. A method of producing a SmFeN-based rare earth magnet, the method comprising:
dispersing a SmFeN-based anisotropic magnetic powder comprising Sm, Fe, and N using a resin-coated metal media or a resin-coated ceramic media in a vibration mill or a ball mill to obtain a dispersed SmFeN-based anisotropic magnetic powder by removing the resin-coated metal media or the resin-coated ceramic media;
mixing the dispersed SmFeN-based anisotropic magnetic powder with a modifier powder to obtain a powder mixture;
compacting the powder mixture in a magnetic field to obtain a magnetic field compact;
pressure-sintering the magnetic field compact to obtain a sintered compact; and
heat treating the sintered compact,
wherein a diameter of the resin-coated metal media or the resin-coated ceramic media is at least 2 mm but not more than 100 mm.

2. The method of producing a SmFeN-based rare earth magnet according to claim 1 ,
wherein the dispersed SmFeN-based anisotropic magnetic powder has an average particle size of at least 2.5 μm but not more than 5 μm, a residual magnetization σr of not less than 150 emu/g, and an oxygen content of not higher than 0.4% by mass.

3. The method of producing a SmFeN-based rare earth magnet according to claim 1 ,
wherein the dispersed SmFeN-based anisotropic magnetic powder has a particle size D50 corresponding to 50th percentile of the cumulative particle size distribution by volume of the SmFeN-based anisotropic magnetic powder of at least 2 μm but not more than 5 μm, a residual magnetization σr of not less than 150 emu/g, and an oxygen content of not higher than 0.4% by mass.

4. The method of producing a SmFeN-based rare earth magnet according to claim 1 ,
wherein the resin-coated metal media is a nylon resin-coated iron core media.

5. The method of producing a SmFeN-based rare earth magnet according to claim 1 ,
wherein the modifier powder is a metallic zinc powder.

6. The method of producing a SmFeN-based rare earth magnet according to claim 1 ,
wherein, in the mixing the dispersed SmFeN-based anisotropic magnetic powder with the modifier powder, an amount of the modifier powder relative to an amount of the dispersed SmFeN-based anisotropic magnetic powder is not more than 15% by mass.

7. The method of producing a SmFeN-based rare earth magnet according to claim 1 ,
wherein, in the mixing the dispersed SmFeN-based anisotropic magnetic powder with the modifier powder, an amount of the modifier powder relative to an amount of the dispersed SmFeN-based anisotropic magnetic powder is not less than 1% by mass.

8. The method of producing a SmFeN-based rare earth magnet according to claim 1 ,
wherein, in the pressure-sintering the magnetic field compact to obtain the sintered compact, the magnetic field compact is pressure-sintered at a temperature not lower than 310° C.

9. The method of producing a SmFeN-based rare earth magnet according to claim 1 ,
wherein, in the pressure-sintering the magnetic field compact to obtain the sintered compact, the magnetic field compact is pressure-sintered at a temperature not higher than 400° C.

10. The method of producing a SmFeN-based rare earth magnet according to claim 1 ,
wherein the modifier powder comprises zinc, a zinc alloy, or a combination thereof.

Assignees

• Nichia Corp
• Toyota Motor Co Ltd

Inventors

• Maehara Hisashi
• Kume Michiya
• Ito Masaaki

Classifications

• H01F1/059

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

• H01F1/0558

  bonded together · CPC title

• B22F2999/00

  Aspects linked to processes or compositions used in powder metallurgy · CPC title

• B22F2998/10

  Processes characterised by the sequence of their steps · CPC title

• B22F1/102

  Metallic powder coated with organic material · CPC title