| 摘要 |
PURPOSE:To improve productivity and to obviate deterioration in the quality of a magnetic disk by adopting an oxalic acid film in place of a sulfuric acid film as an anodically oxidized film to be formed on the surface of an aluminum substrate material. CONSTITUTION:After the surface of the aluminum substrate material is roughly ground, the surface is subjected to the anodic oxidation treatment by an oxalic acid method to coat and form the oxalic acid film on the surface of the substrate material surface in the roughly ground state. The film surface is then polished to desired surface roughness. The oxalic acid film has not only the heat resistance and hardness superior to the sulfuric acid film but also the excellent surface smoothness of the film itself. The oxalic acid film is coated and formed on the substrate surface and is finished by polishing without executing diamond turning, etc., after the rough grinding. The productivity of the aluminum substrate is thereby improved and eventually the production cost is reduced. The performance of the magnetic disk is thus maintained stable and satisfactory over a long period of time.
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