US 12,462,976 B2
Method for manufacturing rare earth magnet
Hyun Seok Lim, Seoul (KR); Goon Seung Gong, Daegu (KR); Hyun Min Nah, Seoul (KR); Dong Hwan Kim, Daegu (KR); Won Kyu Park, Daegu (KR); and Seok Bae, Seoul (KR)
Assigned to LG INNOTEK CO., LTD., Seoul (KR)
Appl. No. 17/297,600
Filed by LG INNOTEK CO., LTD., Seoul (KR)
PCT Filed Nov. 27, 2019, PCT No. PCT/KR2019/016464
§ 371(c)(1), (2) Date May 27, 2021,
PCT Pub. No. WO2020/111772, PCT Pub. Date Jun. 4, 2020.
Claims priority of application No. 10-2018-0148750 (KR), filed on Nov. 27, 2018.
Prior Publication US 2022/0028609 A1, Jan. 27, 2022
Int. Cl. H01F 41/02 (2006.01); H01F 1/057 (2006.01)
CPC H01F 41/0293 (2013.01) [H01F 1/0577 (2013.01); C22C 2202/02 (2013.01)] 7 Claims
OG exemplary drawing
 
1. A method of manufacturing a rare-earth magnet, the method comprising:
preparing a magnetic sintered body including RE, Fe, and B as compositional components, wherein RE is selected from one or two or more selected from among rare earth elements;
applying a first solution containing a first grain boundary diffusion material to the magnetic sintered body;
performing a first grain boundary diffusion by heat-treating the magnetic sintered body;
applying a second solution containing a second grain boundary diffusion material to the magnetic sintered body; and
performing a second grain boundary diffusion by heat-treating the magnetic sintered body,
wherein the second grain boundary diffusion is performed after the first grain boundary diffusion is performed,
wherein the first grain boundary diffusion material comprises a heavy rare earth element (HREE) hydride,
wherein the second grain boundary diffusion material comprises a light rare earth element (LREE) hydride,
wherein the heavy rare earth element (HREE) hydride comprises at least one of Dy hydride, Tb hydride, or Ho hydride,
wherein the light rare earth element (LREE) hydride comprises Nd hydride,
wherein a coating amount of the first grain boundary diffusion material is different from a coating amount of the second grain boundary diffusion material,
wherein the first grain boundary diffusion material is a heavy rare earth element (HREE) hydride, and an amount of the first grain boundary diffusion material is 0.1 parts by weight to 1.0 part by weight based on the total weight of 100 parts by weight of the rare-earth magnet,
wherein the second grain boundary diffusion material is a light rare earth element (LREE) hydride, and an amount of the second grain boundary diffusion material is 0.1 parts by weight to 0.5 parts by weight based on the total weight of 100 parts by weight of the rare-earth magnet, and
wherein after performing the second grain boundary diffusion by heat-treating the magnetic sintered body, the light rare earth element (LREE) and the heavy rare earth element (HREE) remain in the magnetic sintered body.