| 简介 |
PROBLEM TO BE SOLVED : To provide a method for producing a rare-earth-iron-nitrogen-based magnet powder, which subjects a raw powder that has been wet-blended to reduction and diffusion treatment, prevents the generation of a nucleus having a reverse axis and the grain growth due to heat generation, and can stably produce an inexpensive magnet powder having high characteristics.
SOLUTION : This production method includes : preparing an iron oxide powder and an oxide powder of a rare-earth element which become a raw material of a magnet, at a ratio of predetermined amounts, and wet-blending them in an organic solvent; or slurrying the iron oxide powder with a water medium, adding a salt of an alkali metal or an alkaline-earth metal to the slurry when the slurry has a pH value smaller than 7.0, and then wet-blending an oxide powder of a rare-earth element; filtrating and drying the mixture to obtain a mixed powder; subjecting the obtained mixed powder to hydrogen heat-treatment so that an amount of a produced complex oxide of a rare-earth element and iron becomes 6 wt.% or less; further adding a predetermined amount of an alkaline earth metal to the mixed powder; heat-treating and cooling the powder in an inert gas atmosphere to obtain a rare earth-iron-based mother alloy; subsequently nitriding the mother alloy in a current of a mixed gas containing ammonia and hydrogen; subsequently wet-treating the obtained nitrided material; and pulverizing the obtained crude powder.
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