| 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 Fe2O3 particles into an alkali aqueous solution, adding an alkaline earth metallic salt and a Co salt to the dispersion and dividedly adding a ferrous salt. CONSTITUTION:Needle-like gamma-Fe2O3 particles as nuclei are dispersed into an aqueous solution of an alkali to have 1.6-3.0mol/l OH<-> ion concentration. Then 1/2 based on an amount to be added of an aqueous solution of a ferrous salt is added to the dispersion, further an aqueous solution of an alkaline earth metal and an aqueous solution of Co salt are added to the dispersion and stirred. Then, the rest of the aqueous solution of ferrous salt is added to the dispersion and stirred. Slurry having finished the reaction is washed with water, dehydrated and dried. By this method Co-containing iron oxide magnetic powder for high- quality recording can be readily produced by addition of a small amount of Co. |
