Method for producing magnet powder and sintered magnet produced by the same

Patent metadata

Field	Value
Publication number	US-12394546-B2
Application number	US-202017616518-A
Country	US
Kind code	B2
Filing date	Jul 6, 2020
Priority date	Aug 2, 2019
Publication date	Aug 19, 2025
Grant date	Aug 19, 2025

Abstract

A method for producing a magnet powder is provided in the present disclosure. The method includes synthesizing a R—Fe—B-based magnet powder by a reduction-diffusion process, coating an antioxidant film onto a surface of the R—Fe—B-based magnet powder, and immersing and cleaning the R—F—B-based magnet powder in an aqueous solvent or a non-aqueous solvent, wherein R is Nd, Pr, Dy or Tb, and wherein the antioxidant film includes a compound containing at least one amino group.

First claim

The invention claimed is:

1. A method for producing a magnet powder comprising:
synthesizing a R—Fe—B-based magnet powder by a reduction-diffusion process;
coating an antioxidant film onto a surface of the R—Fe—B-based magnet powder; and
immersing and cleaning the R—Fe—B-based magnet powder in an aqueous solvent or a non-aqueous solvent, and
wherein coating the antioxidant film onto the surface of the R—Fe—B-based magnet powder is performed before immersing and cleaning the R—Fe—B-based magnet powder,
wherein R is Nd, Pr, Dy or Tb,
wherein the antioxidant film includes a compound containing at least one amino group, and
wherein the compound includes at least one selected from the group consisting of ethylene diamine and 2-ethylhexyloxy propyl amine.

2. The method according to claim 1 ,
wherein the compound further includes at least one selected from the group consisting of tris(2-aminoethyl)amine and 1,2-diaminopropane.

3. The method according to claim 1 ,
wherein synthesizing the R—Fe—B-based magnet powder includes mixing rare earth oxide, boron and iron to prepare a primary mixture, adding a reducing agent to the primary mixture to prepare a secondary mixture, and heating the secondary mixture to a temperature of 800 to 1100 degrees Celsius, and
the reducing agent includes at least one selected from the group consisting of Ca, CaH 2 and Mg.

4. The method according to claim 1 ,
wherein at least one selected from the group consisting of NH 4 NO 3 , NH 4 Cl and ethylenediaminetetraacetic acid (EDTA) is dissolved in the aqueous solvent or the non-aqueous solvent.

5. The method according to claim 1 ,
wherein the aqueous solvent includes deionized water, and the non-aqueous solvent includes at least one selected from the group consisting of methanol, ethanol, acetone, acetonitrile, and tetrahydrofuran.

6. The method according to claim 1 ,
wherein the R—Fe—B-based magnet powder includes NdFeB-based magnet powder.

7. The method according to claim 1 ,
wherein cleaning the R—Fe—B-based magnet powder is repeated two or more times.

Assignees

• Lg Chemical Ltd

Inventors

• Choe Jinhyeok
• Kwon Soon Jae
• Uh Hyounsoo
• Jeon Kwang Won
• Moon Seung Ho
• Chun Jakyu

Classifications

• H01F1/0577

  sintered · CPC title

• H01F1/0572 Primary

  with a protective layer · CPC title

• C22C2202/02

  Magnetic · CPC title

• C22C38/005

  containing rare earths, i.e. Sc, Y, Lanthanides · CPC title

• H01F1/086

  sintered · CPC title