| 摘要 |
PURPOSE:To produce ferromagnetic metallic powder having excellent characteristics as magnetic recording bodies by reducing the acicular iron oxide powder obtd. from acicular iron oxyhydroxide under specific conditions. CONSTITUTION:The acicular iron oxyhydroxide obtd. by neutralizing an aq. soln. of ferrous salt or a mixture of ferrous salt and ferric salt with an alkali agent then subjecting the same to oxidation reaction with an oxidative gas is heated to 300-1,000 deg.C in air, whereby the acicular iron oxide powder is obtd. This powder is washed with distilled water and is washed until the electric conductivity of the filtrate does not change any longer. The powder is dried and is then heated to 380 deg.C in steam flow, whereby the powder is reduced to metallic iron powder. Or the acicular iron oxide powder is heated to 150-500 deg.C in a reducing gas and after such heat treatment, the powder is washed thoroughly in the same manner as mentioned above, whereby the powder is reduced to iron powder. The ferromagnetic metallic powder as magnetic recording media having excellent stability for oxidation, corrosion resistance and distribution property and having high saturation magnetization and coersive force is obtained. |
