Process of producing aluminum substrate for magnetic recording media
CA 1237694 A · Owner: Nippon Light Metal Company Limited · Inventors: Oka, Yasuo; Hirayama, Yoshio; Kajiyama, Takashi
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An aluminum substrate suitable for making high-density magnetic recording media is produced by anodising a surface of the aluminum material in an aqueous chromic acid solution at an electrolytic voltage higher than 60 volts. The anodic film thus formed has no black spot defects as 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. - 16 -
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Granted June 7, 1988. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended June 7, 2005.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.