MANUFACTURE OF MAGNETIC RECORDING MEDIUM

摘要

PURPOSE:To prevent the production of any cracks in a substrate and the roughing of the surace of a magnetic recording medium, by a method wherein when a ferrite film formed on a substrate is oxidized to manufacture a gamma-Fe2O3 medium, the temperature of the heat treatment for forming the gamma-Fe2O3 is lowered. CONSTITUTION:An Fe3O4 film having a thickness of 0.065mum is formed on a substrate. The film is placed in a oxidizing furnace in the atmospheric air to effect a heat treatment for transforming the film into a gamma-Fe2O3 thereby to form a gamma-Fe2O3 medium. Making the heat treatment temperature lower than the maximum endurable temperature of the substrate prevents the production of any cracks. A second Fe3O4 film is formed on the gamma-Fe2O3 medium formed on the substrate. This is subsequently placed in the oxidizing furnace in the atmospheric air and heat-treated at about 250 deg.C to form another gamma-Fe2O3 medium. In a similar manner, an Fe3O4 film having a thickness of about 0.066mum is laminated on the second gamma-Fe2O3 film and heat-treated to form still another gamma-Fe2O3 medium, thereby to finally form a gamma-Fe2O3 medium having a total film thickness of about 0.2mum.