Method for the production of a metal strip coated with a coating of chromium and chromium oxide using an electrolyte solution with a trivalent chromium compound

US11274373B2 · kind B2 · utility

Assignees

• thyssenkrupp Rasselstein GmbH · DE
• thyssenkrupp AG · DE

Inventors

• Andrea Marmann · Piesport, DE
• Christoph Molls · Bonn, DE
• Rainer Görtz · Bad Breisig, DE
• Thomas Lenz · Laatzen, DE

Key dates

• Filing date: Dec 12, 2019
• Grant date: Mar 15, 2022
• Expiry date: Jan 14, 2040

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C25D17/28
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

A method for producing a metal strip coated with a coating that contains chromium metal and chromium oxide and is electrolytically deposited from an electrolyte solution that contains a trivalent chromium compound onto the metal strip by bringing the metal strip, which is connected as the cathode, into contact with the electrolyte solution. An efficient deposition of coating with a high proportion of chromium oxide is obtained by successively passing the metal strip through a plurality of electrolysis tanks. The electrolyte solution in at least the last electrolysis tank, as viewed in the strip travel direction, or in a rear group of electrolysis tanks has an average temperature of at most 40° C., and the electrolysis time, during which the metal strip is in electrolytically effective contact with the electrolyte solution in the last electrolysis tank or in the rear group of electrolysis tanks is less than 2.0 seconds.