| 摘要 |
PURPOSE:To prepare magnetic powder for magnetic recording use, having stable coercive force and high stability under heat and pressure, by carrying out the reaction of a Co salt with an alkali in a hot slurry of gamma-Fe2O3 dispersion, and if necessary, carrying out the addition of an aqueous solution of ferrous salt also under heating. CONSTITUTION:gamma-Fe2O3 powder is dispersed homogeneously in water to obtain a slurry, mixed with a solution of a Co salt, e.g. solution of cobalt sulfate, heated at room temp. to 100 deg.C, added with an alkaline aqueous solution, e.g. solution of caustic soda to precipitate cobalt hydroxide, and then added with an aqueous solution of FeSO4 after cooling or under heating. The process promotes the penetration of Co ions into the gamma-Fe2O3 core, facilitates the precipitation of coarser cobalt hydroxide particles, increases the mutual interaction of the Co ions with ferrous ions, and improves the coecive force of the product. Furthermore, the stability against heat and pressure can be improved because of the closer contact of the cobalt hydroxide to the surface of the gamma-Fe2O3 particle. |
