Pretreatment before painting of composite metal structures containing aluminum portions

US6720032B1 · kind B1 · utility

Assignee

• Henkel Kommanditgesellschaft auf Aktien · DE

Inventors

• Peter Kuhm · Hilden, DE
• Michael L. Sienkowski · Warren, US
• Gerald J. Cormier · Troy, US
• Matthias Hamacher · Frechen, DE
• Jurgen Geke · Düsseldorf, DE
• Volkhard Enke · Leverkusen, DE
• Jan-Willem Brouwer · Willich, DE
• Hubert Venschott · Pforzheim, DE

Key dates

• Filing date: Mar 10, 2000
• Grant date: Apr 13, 2004
• Expiry date: Mar 10, 2020

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C23C22/83
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

In a process for the chemical pretreatment before painting of composite metal structures that contain aluminum or aluminum alloy portions together with steel, galvanized steel and/or alloy-galvanized steel portions, in a first step the metal structure is treated with a zinc phosphating solution that forms a surface-covering crystalline zinc phosphate layer on steel and on galvanized or alloy-galvanized steel, but without forming a zinc phosphate layer on the aluminum portions, and then in a second step the metal structure is brought into contact with a treatment solution that does not excessively dissolve the crystalline zinc phosphate layer on steel, galvanized and/or alloy-galvanized steel, but forms a conversion layer on the aluminum portions.