US 11,948,734 B2
Method about increasing the coercivity of a sintered type NdFeB permanent magnet
Chuanshen Wang, Shandong (CN); Kunkun Yang, Shandong (CN); Zhongjie Peng, Shandong (CN); and Kaihong Ding, Shandong (CN)
Assigned to Yantai Shougang Magnetic Materials Inc, Shandong (CN)
Filed by Yantai Shougang Magnetic Materials Inc, Shandong (CN)
Filed on Nov. 26, 2020, as Appl. No. 17/105,533.
Claims priority of application No. 201911198033.0 (CN), filed on Nov. 29, 2019.
Prior Publication US 2021/0166872 A1, Jun. 3, 2021
Int. Cl. H01F 41/02 (2006.01); H01F 1/057 (2006.01)
CPC H01F 41/0293 (2013.01) [H01F 1/0577 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method for increasing the coercivity of a sintered type NdFeB permanent magnet (2), the method comprising the following steps:
a) preparing of an organic film (3) with a predetermined thickness on a surface of the sintered type NdFeB permanent magnet (2);
b) creating holes (4) in the organic film (3) according to a given pattern with the holes (4) extending to the surface of the sintered type NdFeB permanent magnet (2);
c) filling the holes (4) with a metal powder (1), the metal powder (1) including or consisting of at least one of Dy and Tb; and
d) performing a thermally induced grain boundary diffusion process.