| 摘要 |
PURPOSE:To produce ferromagnetic metallic powder having an oxide film which is good in oxidation resistant stability by subjecting the ferromagnetic metallic powder essentially consisting of iron having an oxidized surface layer part to heating and annealing in an inert gaseous atmosphere then allowing the powder to contact an oxygen-contg. gas. CONSTITUTION:The ferromagnetic metallic powder essentially consisting of iron is allowed to contact the oxygen-contg. gas in an org. solvent or gaseous phase to oxidize the surface layer part. The above-mentioned powder is then heated and annealed in a gaseous phase and inert gaseous atmosphere. The powder is thereafter allowed to contact the oxygen-contg. gas again in the org. solvent or gaseous phase to form the uniform and dense oxide film. The above-mentioned heating and annealing are adequately executed for 0.5-24hr, more particularly 1-5hr at 80-600 deg.C, more particularly 90-200 deg.C. An org. solvent such as benzene which is inert to the above-mentioned powder is preferably used for the above-mentioned org. solvent at >=2 times the pts.wt. of the above-mentioned powder. The gas prepd. by diluting air or O2 with N2, He, Ar, Ne, etc., is suitable as the above-mentioned oxygen-contg. gas and N2, He, Ar, Ne, etc. are adequate for the inert gaseous atmosphere. |
