Chromium-zinc anti-tarnish coating for copper foil having a dark color
US5250363A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 26, 1992 |
| Grant date | Oct 5, 1993 |
| Priority date | — |
| Expiry date | Oct 26, 2012 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/12903
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A technique for improving the tarnish and oxidation resistance of metallic substrate is disclosed. The substrate is immersed in an aqueous solution containing sodium hydroxide, zinc ions and chromium (VI) ions. Either the temperature of the aqueous solution or the current density is selected so that at least one surface of the substrate is coated with a nontransparent layer. A chromium-zinc coating is electrolytically applied. The coating provides tarnish resistance at temperatures in excess of 230.degree. C. The coating is removable by immersion in sulfuric acid. Improved results are obtained by rinsing deionized water containing a small amount of an alkaline or alkaline earth hydroxide.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.