发明名称 |
Method for producing R-T-B sintered magnet |
摘要 |
A method for producing a sintered R-T-B based magnet includes providing a sintered R-T-B based magnet body, of which the rare-earth-element mole fraction falls within the range of 31 mass % to 37 mass %; providing an RH diffusion source including a heavy rare-earth element RH (which is at least one of Dy and Tb) and 30 mass % to 80 mass % of Fe; loading the sintered magnet body and the RH diffusion source into a processing chamber so that the magnet body and the diffusion source are movable relative to each other and readily brought close to, or in contact with, each other; and performing an RH diffusion process by conducting a heat treatment on the sintered magnet body and the RH diffusion source at a process temperature of 700° C. to 1000° C. while moving the sintered magnet body and the RH diffusion source either continuously or discontinuously. |
申请公布号 |
US9478332(B2) |
申请公布日期 |
2016.10.25 |
申请号 |
US201314372543 |
申请日期 |
2013.01.17 |
申请人 |
HITACHI METALS, LTD. |
发明人 |
Kuniyoshi Futoshi;Ishii Rintaro;Yamagata Ryouichi |
分类号 |
H01F1/057;H01F1/053;C22C28/00;C22C38/00;C22C30/00;C22C38/06;C22C38/10;C22C38/16;B22F9/02;H01F41/02;B22F3/26;H01F7/02;B22F3/24;B22F3/00 |
主分类号 |
H01F1/057 |
代理机构 |
Keating & Bennett, LLP |
代理人 |
Keating & Bennett, LLP |
主权项 |
1. A method for producing a sintered magnet, the method comprising the steps of:
providing a sintered R-T-B based magnet body, of which the R mole fraction that is defined by the content of a rare-earth element falls within the range of 31 mass % to 37 mass %; providing an RH diffusion source including a heavy rare-earth element RH, which is at least one of Dy and Tb, and including a volume percentage of an RHFe2 compound and/or an RHFe3 compound of 90% or more; loading the sintered magnet body and the RH diffusion source into a processing chamber so that the magnet body and the diffusion source are movable relative to each other and readily brought close to, or in contact with, each other; and performing an RH diffusion process by conducting a heat treatment on the sintered magnet body and the RH diffusion source at a process temperature of 870° C. to 970° C. and at an internal processing pressure of 10−2 Pa to atmospheric pressure while rotating the processing chamber at a peripheral velocity of 0.01 m/s or more to continuously or discontinuously move the sintered magnet body and the RH diffusion source in the processing chamber; wherein the sintered magnet body has an effective rare-earth content of 28 mass % to 35 mass %, in which the effective rare-earth content is defined by the following equation:
the effective rare-earth content=the R mole fraction−(6×O mole fraction+8×C mole fraction+10×N mole fraction),where the O mole fraction is an oxygen content of the sintered magnet body, the C mole fraction is a carbon content of the sintered magnet body, and the N mole fraction is a nitrogen content of the sintered magnet body. |
地址 |
Tokyo JP |