Manufacturing method of sintered magnet, and sintered magnet

Patent metadata

Field	Value
Publication number	US-11657933-B2
Application number	US-201816614426-A
Country	US
Kind code	B2
Filing date	Nov 28, 2018
Priority date	Nov 28, 2017
Publication date	May 23, 2023
Grant date	May 23, 2023

Abstract

A sintered magnet and method of manufacturing the same are disclosed herein. According to an exemplary embodiment, a manufacturing method of a sintered magnet includes mixing the neodymium iron boron (NdFeB)-based powders and rare-earth hydride powders to prepare a mixture, heat-treating the mixture at a temperature of 600 to 850° C., and sintering the heat-treated mixture at a temperature of 1000 to 1100° C. to prepare the sintered magnet, wherein the rare earth hydride powders are neodymium hydride (NdH2) powders or mixed powers of NdH2 and praseodymium hydride (PrH2). In an embodiment, the NdFeB-based powders are prepared by a reduction-diffusion method.

First claim

What is claimed is:

1. A manufacturing method of a sintered magnet, the method comprising:
mixing neodymium iron boron (NdFeB)-based powders and rare-earth hydride powders to prepare a mixture;
heat-treating the mixture at a temperature of 600 to 850° C. for a time period sufficient to separate the rare-earth hydride powders into rare earth metals and hydrogen (H 2 ) gas and to remove the H 2 gas; and then
sintering the heat-treated mixture at a temperature of 1000 to 1100° C. to prepare the sintered magnet,
wherein the rare-earth hydride powders are neodymium hydride (NdH 2 ) powders or mixed powders of NdH 2 and praseodymium hydride (PrH 2 ).

2. The manufacturing method of claim 1 , wherein
the mixed powers of NdH 2 and PrH 2 have a mixing weight ratio in a range of 75:25 to 80:20.

3. The manufacturing method of claim 1 , wherein
the sintering of the heat-treated mixture at the temperature of 1000 to 1100° C. is performed for 30 min to 4 h.

4. The manufacturing method of claim 1 , wherein, prior to the heating-treating of the mixture,
the rare-earth hydride powders are present in the mixture in a range of 1 to 25 wt %.

5. The manufacturing method of claim 1 , wherein
a size of the crystal grains of the sintered magnet is 1 to 10 μm.

6. The manufacturing method of claim 1 , wherein,
the mixing of the NdFeB-based powders and the rare-earth hydride powders further comprises
mixing Cu powders with the NdFeB-based powders and the rare-earth hydride powders to prepare the mixture.

7. The manufacturing method of claim 6 , wherein, prior to heat-treating the mixture,
the rare earth hydride powders and the Cu powders are present in the mixture in a weight ratio of 7:3.

8. The manufacturing method of claim 1 , wherein, prior to mixing, the NdFeB-based powders are prepared by a reduction-diffusion method comprising:
preparing a first mixture by mixing a neodymium oxide, boron, and iron;
preparing a second mixture by adding calcium to the first mixture and mixing them; and
heating the second mixture to a temperature of 800 to 1100° C. to prepare the NdFeB-based powders.

Assignees

• Lg Chemical Ltd

Inventors

• Choi Ikjin
• Lee Jung Goo
• In Juneho
• Kwon Soon Jae
• Uh Hyounsoo
• Choe Jinhyeok
• Kim Ingyu
• Shin Eunjeong

Classifications

• B22F2301/355

  Rare Earth - Fe intermetallic alloys · CPC title

• H01F1/086

  sintered · CPC title

• H01F1/0572 Primary

  with a protective layer · CPC title

• C22C38/16

  containing copper · CPC title

• B22F3/10

  Sintering only · CPC title