The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 26, 1985
Filed:
Mar. 01, 1984
Applicant:
Inventors:
Koichi Yoshida, Shizuoka, JP;
Yoshio Hirayama, Shizuoka, JP;
Yasuo Oka, Shizuoka, JP;
Takashi Kajiyama, Shizuoka, JP;
Assignee:
Nippon Light Metal Company Limited, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C25D / ; C25D / ;
U.S. Cl.
CPC ...
204 58 ;
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.