METHOD FOR MANUFACTURING RARE EARTH-TRANSITION METAL-NITROGEN BASED MAGNET POWDER OF HIGH WEATHER RE

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PROBLEM TO BE SOLVED : To provide a method for manufacturing rare earth-transition metal-nitrogen based magnet powder of high weather resistance, which enables the enhancement of rare earth-transition metal-nitrogen based magnet powder in weather resistance, and which suffers no reduction in coercive force even when such magnet powder is exposed under the condition of 80°C at a relative humidity of 90% for a long time. SOLUTION : A method for manufacturing rare earth-transition metal-nitrogen based magnet powder, comprises : a first step which includes putting rare earth-transition metal-nitrogen based magnet powder in a media mixing mill of a pulverizer together with a phosphoric acid-based compound, an organic solvent and a pulverizing medium, and adding a coupling agent to the resultant liquid solution while pulverizing, thereby forming a primary coat including the coupling agent and the phosphate on the surface of pulverized magnet powder with the aid of the coupling agent; a second step which includes further adding a hydrolyzable silane compound into the resultant liquid solution, thereby forming a silica coat on the surface of the primary coat by hydrolysis polycondensation; and a third step which includes drying the resultant slurry by heating at a temperature of 100-400°C in vacuum or inert gas atmosphere. SELECTED DRAWING : None COPYRIGHT : (C)2016, JPO&INPIT