Process of producing aluminum substrate for magnetic recording media
First Claim
1. A process of producing an aluminum substrate for magnetic recording media, which comprises subjecting an aluminum material to an electrolytic treatment by a constant voltage process at an electrolytic voltage higher than 60 volts using an aqueous solution of 1.5 to 15% by weight chromic acid as the electrolyte at an operating temperature of 30°
- -50°
C.
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Abstract
An aluminum substrate suitable for making high-density magnetic recording media is produced by anodizing a surface of the aluminum substrate in an aqueous chromic acid solution at an electrolytic voltage higher than 60 volts. The anodic film thus formed has no black spot defects and also exhibits no cracks when the substrate is heated at a high temperature for forming a magnetic recording layer.
The effect is further improved by adding a small amount of oxalic acid to the electrolyte.
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6 Claims
- 1. A process of producing an aluminum substrate for magnetic recording media, which comprises subjecting an aluminum material to an electrolytic treatment by a constant voltage process at an electrolytic voltage higher than 60 volts using an aqueous solution of 1.5 to 15% by weight chromic acid as the electrolyte at an operating temperature of 30°
Specification