US 11,987,868 B2
Preparation method of a rare earth anisotropic bonded magnetic powder
Yang Luo, Beijing (CN); Zilong Wang, Beijing (CN); Yuanfei Yang, Beijing (CN); Zhou Hu, Beijing (CN); Dunbo Yu, Beijing (CN); Jiajun Xie, Beijing (CN); Yifan Liao, Beijing (CN); and Zhongkai Wang, Beijing (CN)
Assigned to GRIREM ADVANCED MATERIALS CO., LTD., Beijing (CN); and GRIREM HI-TECH CO., LTD., Langfang (CN)
Filed by GRIREM ADVANCED MATERIALS CO., LTD., Beijing (CN); and GRIREM HI-TECH CO., LTD., Langfang (CN)
Filed on Nov. 5, 2020, as Appl. No. 17/090,703.
Claims priority of application No. 201911076252.1 (CN), filed on Nov. 6, 2019.
Prior Publication US 2021/0129217 A1, May 6, 2021
Int. Cl. B22F 1/142 (2022.01); B22F 9/04 (2006.01); C22C 1/10 (2023.01); C22C 38/00 (2006.01); H01F 1/057 (2006.01)
CPC C22C 38/005 (2013.01) [B22F 1/142 (2022.01); B22F 9/04 (2013.01); C22C 1/1084 (2013.01); H01F 1/0576 (2013.01); B22F 2009/041 (2013.01); B22F 2201/013 (2013.01); B22F 2201/20 (2013.01); B22F 2301/355 (2013.01); C22C 2202/02 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A preparation method of a rare earth anisotropic bonded magnetic powder, wherein the method comprises:
(1) Preparing a raw powder with RTBH as a main component; wherein R is Nd or Pr/Nd, and T is any combination of transition metals and at least containing Fe;
(2) Adding La hydride or Ce hydride and copper powder to the raw powder to make a mixture; wherein the La hydride or Ce hydride is added at a ratio of higher than 3.5 wt % and lower than 5.0 wt %, based on a weight of the raw powder; and the copper powder is added at a ratio of 25-100 wt %, based on a weight of the La hydride or Ce hydride;
(3) Subjecting the mixture to atmosphere diffusion heat treatment to obtain the rare earth anisotropic bonded magnetic powder,
the raw powder with RTBH as the main component is prepared by a HDDR method, which include the following steps:
a. Hydrogen absorption and disproportionation stage: putting an RTBH alloy in a rotating gas-solid reaction furnace, heating up to 760-860° C. under a hydrogen pressure of 0-0.1 MPa, and then maintaining the hydrogen pressure at 20-100 kPa for 1 h-4 h to complete the hydrogen absorption and disproportionation stage;
b. Slow dehydrogenation and repolymerization stage: after the completion of the hydrogen absorption and disproportionation stage, keeping the temperature in the furnace at 800-900° C., adjusting the hydrogen pressure in the furnace to 1-10 kPa, and maintaining the hydrogen pressure for 10-60 minutes to complete the slow dehydrogenation and repolymerization stage;
c. Complete dehydrogenation stage: after the completion of the slow dehydrogenation and repolymerization stage, vacuum-pumping to a hydrogen pressure below 1 Pa to complete the complete dehydrogenation stage;
d. Cooling stage: after the completion of the complete dehydrogenation stage, cooling down to room temperature to give the raw powder with RTBH as a main component.