Patent ID: 9415444
Filing Date: 2016-08-16
CPC Classification: B22F,C22C,C22F,H01F

Claim Text:
1. A method for producing a sintered R-T-B based magnet, the method comprising the steps of: providing a sintered R-T-B based magnet body; providing an RH diffusion source including a metal or an alloy of a heavy rare-earth element RH, which is at least one selected from the group consisting of Dy and Tb; loading the sintered R-T-B based magnet body and the RH diffusion source into a processing chamber so that the sintered R-T-B based magnet body and the RH diffusion source are moved into contact with each other or into and out of contact with each other; performing an RH diffusion process by conducting a heat treatment on the sintered R-T-B based magnet body and the RH diffusion source at a temperature of 500° C. to 850° C. for at least 10 minutes by heating the processing chamber while moving the sintered R-T-B based magnet body and the RH diffusion source either continuously or discontinuously in the processing chamber so that the magnet body and the RH diffusion source are moved into contact with each other at least once or into and out of contact with each other at least once by rotating the processing chamber at a surface velocity of at least 0.01 m/s. and changing a point of contact between the sintered R-T-B based magnet body and the RH diffusion source and supplying the heavy rare-earth element RH from the RH diffusion source to the sintered R-T-B based magnet body via the point of contact between the sintered R-T-B based magnet body and the RH diffusion source; and introducing a stirring aid member into the processing chamber before or during the RH diffusion process, the stirring aid member being made of zirconia, silicon nitride, silicon carbide, boron nitride, or any combination thereof; wherein in the RH diffusion process, the processing chamber is heated by a heater that is arranged around an outer periphery of the processing chamber, the sintered R-T-B based magnet body and the RH diffusion source that are loaded into the processing chamber are also heated, and the temperature of the sintered R-T-B based magnet body and the RH diffusion source is maintained within a range of 500° C. to 850° C.