| 摘要 |
PURPOSE:To produce magnetic powder having high coercive force, high saturation magnetization, uniform coercive force distribution and improved dispersibility, by dispersing needle-like gamma-Fe2O3 particles into water, adding an alkali and treating. CONSTITUTION:Needle-like gamma-Fe2O3 particles as nuclei are dispersed into water. An aqueous solution containing an alkaline earth metallic salt, Co salt and ferrous salt is added to the dispersion and stirred. Successively and alkali is added to the dispersion, which is adjusted to 3.0-6.0mol/l OH<-> ion concentration. Then the dispersion is treated in a nonoxidizing atmosphere at <= the boiling point of the dispersion to form a Co-containing iron oxide layer on the surface of the needle-like gamma-Fe2O3 particles. By this method Co-containing iron oxide magnetic powder for high-quality magnetic recording can be readily produced. |
