METHOD FOR PRODUCING RARE EARTH-IRON-NITROGEN-BASED MAGNET POWDER

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PROBLEM TO BE SOLVED : To provide a method for producing a rare earth-iron-nitrogen-based magnet powder, capable of preventing a main phase from being dissolved during acid cleaning, thereby enhancing a yield of an obtained magnet powder. SOLUTION : A method for producing rare earth-iron-nitrogen-based magnet powder by a reduction diffusion method includes the steps of : mixing rare earth oxide powder, iron powder, and at least one reducing agent powder selected from an alkali metal, an alkaline earth metal, or a hydride thereof at a specific ratio; heating the mixture in an inert gas atmosphere so that the mixture is reduced and diffused; providing the obtained reaction product with a nitrogen-containing gas comprising nitrogen and/or ammonia, or a mixture gas comprising the nitrogen-containing gas and hydrogen, and then raising the temperature of the reaction product in the gas current to subject the reaction product to nitriding treatment; and putting the reaction product obtained in the reducing and diffusing step, or the nitrided product obtained in the nitriding step into water to disintegrate it, and then subjecting the obtained slurry to wet processing through acid cleaning and water cleaning. In the acid cleaning, a sufficient amount of alcohol is added to a medium, to allow an unusual phase of a magnet to be dissolved but prevent a main phase thereof from being dissolved. SELECTED DRAWING : None COPYRIGHT : (C)2019, JPO&INPIT