US 12,191,059 B2
Rare earth magnet and production method thereof
Masaaki Ito, Anjo (JP); Motoki Hiraoka, Toyota (JP); Reimi Tabuchi, Nisshin (JP); Hisashi Maehara, Itano-gun (JP); and Michiya Kume, Anan (JP)
Assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA, Toyota (JP); and NICHIA CORPORATION, Anan (JP)
Filed by TOYOTA JIDOSHA KABUSHIKI KAISHA, Toyota (JP); and NICHIA CORPORATION, Anan (JP)
Filed on Nov. 14, 2022, as Appl. No. 17/986,366.
Claims priority of application No. 2021-190510 (JP), filed on Nov. 24, 2021.
Prior Publication US 2023/0162898 A1, May 25, 2023
Int. Cl. H01F 1/059 (2006.01); B22F 1/05 (2022.01); B22F 1/142 (2022.01); B22F 1/17 (2022.01); B22F 3/14 (2006.01)
CPC H01F 1/0596 (2013.01) [B22F 1/05 (2022.01); B22F 1/142 (2022.01); B22F 1/17 (2022.01); B22F 3/14 (2013.01); B22F 2203/11 (2013.01); B22F 2301/30 (2013.01); B22F 2301/35 (2013.01); B22F 2302/20 (2013.01); B22F 2303/01 (2013.01); B22F 2303/30 (2013.01); B22F 2304/10 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A production method of a rare earth magnet, comprising:
forming a zinc-containing coating on a particle surface of a magnetic powder having a magnetic phase which contains Sm, Fe and N and at least partially has a crystal structure of either Th2Zn17 type or Th2Ni17 type, to obtain a coated magnetic powder,
compression-molding a mixture of a plurality of the coated magnetic powders in a magnetic field to obtain a magnetic-field molded body,
pressure-sintering the magnetic-field molded body to obtain a sintered body, and
heat-treating the sintered body, wherein
D50 of the magnetic powder is 2.00 μm or more and 3.00 μm or less, the content ratio of the zinc component in the coated magnetic powder is 3 mass % or more and 15 mass % or less relative to the coated magnetic powder, and
the heat treatment is performed at 350° C. or more and 410° C. or less.