Perpendicular magnetic flexible disc by anodic oxidation

Flexible alumite discs were prepared and their recording characteristics and wear resistance is reported. To study the surface roughness of alumite film, single-crystal Al platelets with different crystallographic orientations were prepared and anodic oxidized. The surface smoothness of these anodized films was better in the order [111]>[110]>[100]. For a flexible-disc substrate, >99.999%-pure Al was sputtered onto 50- mu m-thick PET film at a substrate temperature of 80 degrees C. The sputtered film was oriented favorably with [111]. After Fe was electrodeposited in the pores of 2- mu m-thick anodized Al film, it was polished to a thickness of 1 mu m. To test wear durability, the surface of the alumite layer was slightly etched and applied with liquid lubricant. A recording density D₅₀ of 60 kB/in. was obtained, together with a wear resistance of five million head passes.