| 摘要 |
PURPOSE:To obtain ferromagnetic iron powder having excellent dispersibility, orientational property, corrosion resistance and stability in magnetic coating by treating the ferromagnetic iron powder with gas containing coupling agent after surface- oxidizing while using gas containing oxygen. CONSTITUTION:Dewater and burning are executed to alpha-oxy iron hydroxide, etc., to make ferric oxide and successively, reduction under drying is executed by using hydrogen gas, to obtain the ferromagnetic iron powder having iron as main component. The surface of ferromagnetic iron powder is oxidized under atmosphere of mixed gas containing oxygen at <= about 200 deg.C. By this method, the corrosion resistance and weather resistance are given to the ferromagnetic iron powder. After that, if necessary after executing steam-treatment, the ferromagnetic iron powder is treated with the gas containing the coupling agent. It is desirable to use material of silane series of methyl trimethoxysilane, etc., as this coupling agent, and the treating temp. is desirable to execute at <= about 200 deg.C particularly about 0-100 deg.C. By this method, the ferromagnetic iron powder having good magnetic characteristic and also excellent dispersibility, orientational property, corrosion resistance, weather resistance in the magnetic coating for magnetic recording medium is obtd. |
