Electrolyte for producing conversion coatings

US5094727A · kind A · utility

Assignee

• Jenoptik Jena GmbH · DE

Inventors

• Thomas Schwarz · Plaisir, FR
• Ullrich Bayer · Bad Doberan, DE
• Kerstin Haupt · Jena, DE
• Juergen Schmidt · Goldkronach, DE
• Thomas Furche · Jena, DE

Key dates

• Filing date: Apr 25, 1991
• Grant date: Mar 10, 1992
• Expiry date: Apr 25, 2011

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C25D11/14
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

By means of an electrolyte free of ammonia, cyanide, and fluoride, hence low in harmful substances and inoffensive to the environment, optically black coatings having a thickness of less than 10 microns and substantially equal optical absorption and thermal emission capability can be produced on light metals or alloys thereof by spark discharge anodizing. In comparison with prior art conversion coatings obtained by spark discharge anodizing, the coatings produced with this electrolyte have a substantially lower roughness of this electrolyte in spark discharge anodizing provides an alternative mode of coating particularly for structural components or subassemblies of complicated shapes having greater requirements for accuracy to gauge.