PRODUCTION OF MAGNETIC RECORDING MEDIUM

摘要

PURPOSE:To improve remarkably the surface roughness of an Al substrate after the anodic oxidation treatment thereof so that recording density can be improved by using a crystal which has both specific orientations as the Al substrate in producing a magnetic recording medium. CONSTITUTION:The Al substrate of which the surface has the value K defined by the equation is used in a method for producing the magnetic recording medi um by depositing a ferromagnetic material into the fine pores of the film obtd. by anodic oxidation of aluminum or aluminum alloy Al and polishing the sur face thereof. More specifically, the surface roughness is good at >=0.5 value K. Ruggedness of about 1.5% of the thickness of the oxide film is produced at <=0.5 K value and therefore this surface roughness cannot be removed by polishing and the surface roughness after the polishing is much inferior to the surface roughness of the substrate having only the (111) face. The roughness (ruggedness) within the crystal plane and between the crystal planes is small and therefore the surface roughness after polishing is good when the substrate having >=0.5 K is used.