US 12,080,478 B2
Gradient Nd—Fe—B magnet and a method of production
Kunkun Yang, Yantai (CN); Zhongjie Peng, Yantai (CN); and Chuanshen Wang, Yantai (CN)
Assigned to YANTAI SHOUGANG MAGNETIC MATERIALS INC., Yantai (CN)
Filed by Yantai Shougang Magnetic Materials, Inc., Yantai (CN)
Filed on Jul. 1, 2019, as Appl. No. 16/459,448.
Claims priority of application No. 201810694252.7 (CN), filed on Jun. 29, 2018.
Prior Publication US 2020/0005996 A1, Jan. 2, 2020
Int. Cl. H01F 41/02 (2006.01); B22F 3/24 (2006.01); H01F 1/055 (2006.01); H01F 1/057 (2006.01); H01F 7/02 (2006.01)
CPC H01F 41/0293 (2013.01) [H01F 1/0555 (2013.01); H01F 1/0577 (2013.01); H01F 7/0215 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A gradient Nd—Fe—B magnet comprising:
an Nd—Fe—B magnet block extending along a magnetization direction and having a plurality of surfaces perpendicular to said magnetization direction;
a first film containing at least one heavy rare earth element, disposed on one of said surfaces, attached to said Nd—Fe—B magnet block and extending along a periphery of said one of said surfaces and wherein said first film only covers an area of 10% to 65% of said one of said surfaces; and
a second film containing at least one heavy rare earth element, disposed on another one of said surfaces, opposite of said one of said surfaces, attached to said Nd—Fe—B magnet block and extending along a periphery of said another one of said surfaces and wherein said second film only covers an area of 10% to 65% of said another one of said surfaces; and
said first film and said second film being diffused into said Nd—Fe—B magnet block dividing said Nd—Fe—B magnet block into an edge region, a transition region, and a central region along a plane extending perpendicular to said magnetization direction;
wherein said edge region has a coercivity that remains constant in a direction perpendicular to said magnetization direction, and said coercivity of said edge region, along said magnetization direction, gradually decreases from said one of said surfaces and said another one of said surfaces towards a point located between said one of said surfaces and said another one of said surfaces; and
wherein said transition region extends about said center region and said edge region extends about said transition region in concentric relationship.