Anti-corrosion treatment for conversion layers

US8435360B2 · kind B2 · utility

Assignee

• Atotech Deutschland GmbH & Co. KG · DE

Inventors

• Björn Dingwerth · Berlin, DE
• Andreas Noack · Friedrichstadt, DE

Key dates

• Filing date: Jun 13, 2008
• Grant date: May 7, 2013
• Expiry date: Jul 15, 2029

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C23C2222/10
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

The invention relates to a method for producing a coating layer protecting against corrosion wherein a surface which is to be treated is brought into contact with an aqueous treatment solution containing chromium(III) ions and at least one phosphate compound, wherein the ratio of the molar concentration of the chromium(III) ions to the molar concentration of the at least one phosphate compound (calculated as orthophosphate) lies between 1:1.5 and 1:3. The method improves the corrosion protection of metallic, in particular, zinc-containing, surfaces provided with conversion layers. The decorative and functional properties of the surface are maintained or improved. Furthermore, the known problems resulting from the use of chromium(VI)-containing compounds or from post-treatments with polymer dispersions are avoided.