US 12,087,481 B2
Auxiliary alloy casting piece, high-remanence and high-coercive force NdFeB permanent magnet, and preparation methods thereof
Feng Xia, Inner Mongolia (CN); Yulong Fu, Inner Mongolia (CN); Chen Chen, Inner Mongolia (CN); Hailong Zheng, Inner Mongolia (CN); Zichao Wang, Inner Mongolia (CN); Yonghong Liu, Inner Mongolia (CN); Caina Sun, Inner Mongolia (CN); and Yu Wang, Inner Mongolia (CN)
Assigned to Baotou Jinshan Magnetic Material Co., Ltd., Inner Mongolia (CN)
Filed by Baotou Jinshan Magnetic Material Co., Ltd., Inner Mongolia (CN)
Filed on Dec. 30, 2022, as Appl. No. 18/091,899.
Claims priority of application No. 202211255156.5 (CN), filed on Oct. 13, 2022.
Prior Publication US 2024/0127993 A1, Apr. 18, 2024
Int. Cl. B22F 9/02 (2006.01); B22F 1/05 (2022.01); B22F 3/16 (2006.01); C22C 33/04 (2006.01); C22C 38/00 (2006.01); C22C 38/06 (2006.01); C22C 38/10 (2006.01); C22C 38/12 (2006.01); C22C 38/14 (2006.01); H01F 1/057 (2006.01); H01F 41/02 (2006.01); B22F 9/04 (2006.01)
CPC H01F 1/057 (2013.01) [B22F 1/05 (2022.01); B22F 3/16 (2013.01); B22F 9/023 (2013.01); C22C 33/04 (2013.01); C22C 38/002 (2013.01); C22C 38/005 (2013.01); C22C 38/06 (2013.01); C22C 38/10 (2013.01); C22C 38/12 (2013.01); C22C 38/14 (2013.01); H01F 41/0253 (2013.01); B22F 2009/044 (2013.01); B22F 2201/20 (2013.01); B22F 2202/05 (2013.01); B22F 2301/355 (2013.01); B22F 2304/10 (2013.01); B22F 2998/10 (2013.01); C22C 2202/02 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A method for preparing an NdFeB permanent magnet, comprising the following steps:
providing a main alloy casting piece comprising, by mass percentage, 28.5% to 29% of M, 1% to 2% of Co, 0.2% to 0.5% of Ga, 0.05% to 0.15% of Al, 0.9% to 0.92% of B, 0.05% to 0.15% of Ti, and a balance of Fe, wherein the M comprises Pr and Nd; and
subjecting the main alloy casting piece and an auxiliary alloy casting piece to a double-alloy hydrogen decrepitation, a jet milling, an orientation molding, a sintering, and a tempering in sequence, to obtain the NdFeB permanent magnet;
wherein the auxiliary alloy casting piece is prepared by a process comprising the following steps:
providing an auxiliary alloy material comprising, by mass percentage, 40% to 45% of Pr, 1% to 2% of Co, 0.5% to 1% of Ga, 0.6% to 0.8% of B, 0.1% to 0.2% of V, 0.3% to 0.7% of Ti, and a balance of Fe;
smelting the auxiliary alloy material to obtain a smelted material; and
subjecting the smelted material to a rapid-setting casting to obtain the auxiliary alloy casting piece;
wherein the rapid-setting casting comprises a refining, a casting and a cooling in sequence; the casting is conducted at a casting temperature of 1,330° C. to 1,380° C. at a copper roller rotational speed of 60 rpm to 80 rpm; and the cooling is conducted by argon-filled air cooling at a cooling rate of 7° C./min to 15° C./min; and
the auxiliary alloy casting piece has a microstructure with spherical features having a diameter of 3 μm to 15 μm,
wherein the orientation molding is conducted at a magnetic induction intensity of 1.8 T to 2.3 T and a molding pressure of 3 MPa to 6 MPa to obtain a green body; and the green body obtained by the orientation molding has a density of 4.1 g/cm3 to 4.3 g/cm3.