PRODUCTION OF MAGNETIC METALLIC POWDER

摘要

PURPOSE:To form a geothite layer having high corrosion resistance by oxidizing iron powder in gaseous nitrogen flow contg. steam to form an oxidized film on the surface then oxidizing the same in an aq. soln. contg. ferous salt and alkali by an oxidative gas. CONSTITUTION:Iron powder is packed in a reaction tube and gaseous nitrogen contg. specified steam is passed therein at 0.1-100l/min rate to form an oxidized film on the surface of the iron powder. The above-mentioned iron powder is dispersed in an aq. soln. contg. ferrous salt such as ferrous sulfate and alkalis such as caustic soda. Air is blown into the aq. soln. to form goethite (alpha-FeOOH) film further on the surface of the iron powder. The magnetic iron powder having excellent corrosion resistance of the iron powder and dispersibility in binders is obtained by said goethite film.