Manufacturing method of sintered magnet

Patent metadata

Field	Value
Publication number	US-12020835-B2
Application number	US-202017289973-A
Country	US
Kind code	B2
Filing date	Oct 7, 2020
Priority date	Oct 16, 2019
Publication date	Jun 25, 2024
Grant date	Jun 25, 2024

Abstract

A method for manufacturing a sintered magnet according to one embodiment of the present disclosure is provided. The method includes producing an R-T-B-based magnetic powder through a reduction-diffusion method, and sintering the R-T-B-based magnetic powder, wherein R is a rare earth element, and T is a transition metal, and wherein the producing the magnetic powder includes adding a refractory metal sulfide powder to a R-T-B-based raw material.

First claim

The invention claimed is:

1. A method for manufacturing a sintered magnet, comprising:
producing an R-T-B-based magnetic powder through a reduction-diffusion method;
sintering the R-T-B-based magnetic powder to form a sintered R-T-B-based magnet;
producing an eutectic alloy containing Pr, Al, Cu, and Ga; and
infiltrating the eutectic alloy to the sintered R-T-B-based magnet,
wherein R is a rare earth element, and T is a transition metal,
wherein the producing the R-T-B-based magnetic powder includes:

adding a refractory metal sulfide powder to a R-T-B-based raw material,
wherein the infiltration includes:

applying the eutectic alloy to the sintered R-T-B-based magnet, and heat-treating the sintered R-T-B-based magnet to which the eutectic alloy is applied, and
wherein producing the eutectic alloy includes:

mixing PrH 2 , Al, Cu and Ga to prepare an eutectic alloy mixture, pressing the eutectic alloy mixture by a cold isostatic pressing method, and heating the pressed eutectic alloy mixture.

2. The method according to claim 1 ,
wherein R is Nd, Pr, Dy or Tb, and T is Fe.

3. The method according to claim 1 ,
wherein the refractory metal sulfide powder includes at least one of MoS 2 or WS 2 .

4. The method according to claim 1 ,
wherein in the producing the R-T-B-based magnetic powder, the refractory metal sulfide powder is reduced to form a metal precipitate.

5. The method according to claim 4 ,
wherein in the sintering the R-T-B-based magnetic powder, the R-T-B-based magnetic powder is sintered in the presence of the metal precipitate.

6. The method according to claim 1 ,
wherein the sintering the R-T-B-based magnetic powder includes adding a rare earth hydride powder to the R-T-B-based magnet powder.

7. The method according to claim 6 ,
wherein the rare earth hydride powder includes at least one of NdH 2 , PrH 2 , DyH 2 or TbH 2 .

8. The method according to claim 1 ,
wherein the producing the R-T-B-based magnetic powder includes mixing a rare earth oxide, iron, boron, and a reducing agent, followed by heating.

9. The method according to claim 8 ,
wherein the reducing agent includes at least one of Ca, CaH 2 or Mg.

Assignees

• Lg Chemical Ltd

Inventors

• Kim Tae Hoon
• Kwon Soon Jae
• Choi Ikjin
• Kim Ingyu
• Shin Eunjeong
• Moon Seung Ho
• Chun Jakyu

Classifications

• 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

• B22F2301/355

  Rare Earth - Fe intermetallic alloys · CPC title

• H01F1/0573

  obtained by reduction or by hydrogen decrepitation or embrittlement · CPC title

• C21D1/26

  Methods of annealing · CPC title