New technology for the equalization of magnet powder size at a sub-micrometer level

In order to increase the coercivity of a samarium-iron-nitrogen magnet powder, it is necessary to make the reduction-diffusion reaction system uniform. The researchers have therefore developed a rotary heat treatment technology enabling simultaneous multiphase agitation and heat treatment in an airtight space. In addition, the technology for the reduction of particle size developed to date has made it possible to realize an unprecedentedly high level of coercivity for a heavy rare earth-free rare earth-iron magnet powder (approximately 32 kOe at room temperature, equating to approximately 11 kOe at 200 ºC, which represents a yardstick for application in automotive drive motors). Due to the superior heat resistance of the developed magnet powder, it is expected to be employed in the future in magnets that exceed the performance of neodymium magnets under high-temperature conditions.