US 12,462,958 B2
Method of producing phosphate-coated SmFeN-based anisotropic magnetic powder and phosphate-coated SmFeN-based anisotropic magnetic powder
Masahiro Abe, Tokushima (JP); Satoshi Yamanaka, Tokushima (JP); Shuichi Tada, Komatsushima (JP); and Kenta Iwai, Anan (JP)
Assigned to NICHIA CORPORATION, Anan (JP)
Filed by NICHIA CORPORATION, Anan (JP)
Filed on Dec. 27, 2022, as Appl. No. 18/146,752.
Claims priority of application No. 2021-212678 (JP), filed on Dec. 27, 2021.
Prior Publication US 2023/0207166 A1, Jun. 29, 2023
Int. Cl. H01F 1/059 (2006.01); B22F 1/142 (2022.01); B22F 1/145 (2022.01); B22F 1/16 (2022.01); H01F 41/02 (2006.01)
CPC H01F 1/059 (2013.01) [B22F 1/142 (2022.01); B22F 1/145 (2022.01); B22F 1/16 (2022.01); H01F 41/026 (2013.01); B22F 2201/03 (2013.01); B22F 2301/45 (2013.01); B22F 2302/45 (2013.01); B22F 2998/10 (2013.01)] 17 Claims
 
1. A method of producing a phosphate-coated SmFeN-based anisotropic magnetic powder, the method comprising
performing a phosphate treatment comprising adding an inorganic acid to a slurry containing a SmFeN-based anisotropic magnetic powder, water, a phosphate compound, and a rare earth compound containing a rare earth element so that the slurry is adjusted to have a pH of at least 1 and not higher than 4.5 to obtain a phosphate-coated SmFeN-based anisotropic magnetic powder having a surface coated with a phosphate, and
after the phosphate treatment, heat-treating the phosphate-coated SmFeN-based anisotropic magnetic powder at a temperature of at least 150° C. but not higher than 330° C. in an oxygen-containing atmosphere,
wherein the rare earth compound is at least one compound selected from the group consisting of a rare earth hydroxide, a rare earth chloride, a rare earth sulfate, a rare earth nitrate, a rare earth acetate, and a combination thereof, and
wherein the solvent of the slurry is water.