HIGHLY WEATHER RESISTANT RARE EARTH-TRANSITION METAL-NITROGEN BASED MAGNET POWDER, AND MANUFACTURIN

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PROBLEM TO BE SOLVED : To provide a method for manufacturing highly weather resistant rare earth-transition metal-nitrogen based magnet powder, which enables the enhancement in the weather resistance of rare earth-transition metal-nitrogen based magnet powder while keeping a high magnetic property, and which can offer magnet powder suffering no decline in coercive force even after being exposed under a condition of a relative humidity of 90% at 80°C over a long time. SOLUTION : A method for manufacturing highly weather resistant rare earth-transition metal-nitrogen based magnet powder according to the invention comprises the steps of : putting rare earth-transition metal-nitrogen based magnet coarse powder together with an organic solvent to which a phosphoric acid-based compound is added by an amount between 0.1 and 2.0 mol per kilogram of the magnet coarse powder, and a pulverizing medium in a media mixing mill serving as a pulverizer; forming a phosphate coat on the surface of the magnet powder while pulverizing them so that the average particle diameter (D50) becomes 1.0 to less than 3.5 μm; drying a product resulting from the pulverization; and subsequently, performing a heat treatment thereon at least finally under an atmosphere of the air at a temperature between 100°C and 200°C, inclusive. SELECTED DRAWING : None COPYRIGHT : (C)2016, JPO&INPIT