| 简介 |
PROBLEM TO BE SOLVED : To obtain rare earth magnetic powder of high quality improved in oxidation resistance, simultaneously free from deterioration in magnetic properties even in the case of the improvement of the oxidation resistance and free from being influenced by the environment of high temp.-high pressure at the time of kneading it with a resin, or the like. SOLUTION : In a method in which a silica coating thin film is formed on the surface of rare earth magnetic powder composed of an alloy or an intermetallic compd. contg. rare earth elements in the compsn., the magnetic powder is mixed with a silica sol produced from the hydrolysis of an alkyl silicate with a base as a catalyst, and this mixture is heated in an inert atmosphere. Desirably, the thickness of the silica thin film lies in the range of 0.01 to 3 μm. |
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