PURPOSE: To form a magnetic γ-Fe2O3 film at a low temp. and to easily form the magnetic recording medium by utilizing this film even to a base material which is weak to high temp. by forming an Fe3O4 film on the base material of the magnetic recording medium and oxidizing the Fe3O4 film in an oxygen atmosphere of ≥0.5atm oxygen pressure, thereby forming the γ-Fe2O3 film.
CONSTITUTION: Ni-P is chemically plated on the magnetic disk substrate made of an aluminum alloy and after the surface thereof is polished, the thin Fe3O4 film is deposited by about 0.2μm on the Ni-P layer by a sputtering method. This disk substrate is heat treated in an oven into which about 1atm gaseous oxygen is introduced and which is kept at about 280°C to oxidize the Fe3O4 film to the γ-Fe2O3 film. The substrate is heat treated in the oven into which about 1atm gaseous oxygen is introduced to obtain the γ-Fe2O3 film at the temp. lower than in the air. The sufficient oxidation at about 280°C is possible and the γ-Fe2O3 film is applied to base materials weak to high temp., such as base material having the Ni-P plating layer and base material made of plastic, by which the magnetic recording medium is obtd.
SHIBATA HIROSHI
UMEZAKI MITSUMASA
