PRODUCTION METHOD FOR RARE EARTH-IRON-NITROGEN SYSTEM MAGNET POWDER

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PROBLEM TO BE SOLVED : To provide a production method for rare earth-iron-nitrogen magnet powder in which a main phase ratio and uniformity of particles are enhanced by adjusting a heat treatment pattern during reduction diffusion and which has excellent magnetic properties. SOLUTION : A production method for rare earth-iron-nitrogen system magnet powder that includes : a first step of performing reduction diffusion treatment in inert gas by adding a predetermined amount of metal calcium, with a mixture of rare earth oxide powder and iron powder or a mixture further containing at least one of rare earth iron composite oxide or iron oxide therein as a starting material; a second step of nitriding an obtained reduction diffusion reaction product; and a third step of decomposing by wet treating by charging a block of the obtained nitriding treatment product into water and by further charging the obtained magnet coarse powder in a crusher so as to pulverize and micronize the magnet coarse powder. In the reduction diffusion treatment of the first step, first, the starting material and the metal calcium are mixed, the mixture is held at a temperature of 800 to 900°C for 4 to 20 hours, thereafter the temperature is further raised, and the mixture is held at a temperature of 950°C to 1200°C for a predetermined time. SELECTED DRAWING : Figure 2 COPYRIGHT : (C)2018, JPO&INPIT