METHOD OF PRODUCING SmFeN-BASED RARE EARTH MAGNET

Patent metadata

Field	Value
Publication number	US-2024312704-A1
Application number	US-202418600937-A
Country	US
Kind code	A1
Filing date	Mar 11, 2024
Priority date	Mar 14, 2023
Publication date	Sep 19, 2024
Grant date	—

Abstract

A method of producing a SmFeN-based rare earth magnet having excellent magnetic properties is provided.The present disclosure relates to a method of producing a SmFeN-based rare earth magnet in which a powder having a large particle size and a powder having a small particle size are used as SmFeN-based anisotropic magnetic powders, and the powders are separately dry treated at temperatures appropriate for the respective particle sizes when the powders are surface treated using phosphoric acid source to perform phosphoric acid coating.

First claim

What is claimed is:

1 . A method of producing a SmFeN-based rare earth magnet, comprising:
(i) a raw material preparing step of preparing a first SmFeN-based anisotropic magnetic powder having a 50% particle size in a cumulative particle size distribution on a volumetric basis (D 50 ) of 3.0±0.3 μm, and a second SmFeN-based anisotropic magnetic powder having D 50 of 1.6±0.3 μm; (ii) a drying step of subjecting to a phosphoric acid source treatment and drying at a temperature of 80° C. or more and less than 150° C. with respect to the first SmFeN-based anisotropic magnetic powder to obtain a first phosphoric acid-coated SmFeN-based anisotropic magnetic powder; (iii) a drying step of subjecting to a phosphoric acid source treatment and drying at a temperature of 150° C. or more and 250° C. or less with respect to the second SmFeN-based anisotropic magnetic powder to obtain a second phosphoric acid-coated SmFeN-based anisotropic magnetic powder; (iv) a mixing step of mixing the first phosphoric acid-coated SmFeN-based anisotropic magnetic powder obtained in the step (ii), the second phosphoric acid-coated SmFeN-based anisotropic magnetic powder obtained in the step (iii), and a modifier powder containing Zn to prepare a powder mixture; (v) a compression molding step of compression molding the powder mixture obtained in the step (iv) in a magnetic field to obtain a magnetic field molded body; and (vi) a sintering step of pressure sintering the magnetic field molded body obtained in the step (v) to obtain a sintered body.

2 . The method according to claim 1 ,
wherein, in the step (iv), a mass ratio between the first phosphoric acid-coated SmFeN-based anisotropic magnetic powder and the second phosphoric acid-coated SmFeN-based anisotropic magnetic powder (first phosphoric acid-coated SmFeN-based anisotropic magnetic powder:second phosphoric acid-coated SmFeN-based anisotropic magnetic powder) is 8:2 to 9:1.

3 . The method according to claim 1 ,
wherein, in the step (ii), the temperature of drying is 80° C. or more and 140° C. or less.

4 . The method according to claim 1 ,
wherein, in the step (iii), the temperature of drying is 160° C. or more and 220° C. or less.

Assignees

• Toyota Motor Co Ltd
• Nichia Corp

Inventors

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

Classifications

• H01F1/0596

  of rhombic or rhombohedral Th2Zn17 structure or hexagonal Th2Ni17 structure · 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

• H01F41/0266 Primary

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

• B22F2003/1051

  by electric discharge · CPC title

• C22C2202/02

  Magnetic · CPC title