PURPOSE: To greatly improve magnetic characteristics by a method wherein magnetic iron oxide particles containing P are previously treated with an aqueous solvent under the atmospheric pressure, and then any Co compound or any compound of Co and other metals is coated thereon.
CONSTITUTION: Magnetic iron oxide powder containing P is treated with an aqueous solvent such as HCl in order of 0.01W1mol/l or NaOH in order of 0.01W2mol/l under the atmospheric pressure at 10W95°C. This treatment activates the powder surface and allows a Co compound to be coated uniformly and rigidly with ease. Next, powder of a treatment agent is dispersed into an aqueous solution of CoSO4 (Co 0.5W10%) and FeSO4 (Fe 1W20%) and alkali aqueous solution is added thereto. Thereafter, it is treated under non-acidic atmosphere at temperatures below the boiling point to coat the reaction product on the powder surface. The coated magnetic iron oxide slurry is wet-heated at 100W250°C. By so doing, it becomes possible to obtain magnetic iron oxide film powder superior in the coercive force without impairing thermal and mechanical stability.
| JPS61289522 | MAGNETIC RECORDING MEDIUM |
| JPS61248225 | VERTICAL MAGNETIC RECORDING MEDIUM |
| JPS62200520 | THIN METALLIC FILM TYPE MAGNETIC RECORDING MEDIUM |
NAKADA KAZUO
ISHIKAWA TSUNEO
HONMA ICHIROU
HIRAI MASAHARU
OGASAWARA MAKOTO
KAWAMURA TOSHIHIKO
