Process for phosphating metal surfaces

US5268041A · kind A · utility

Assignee

• Metallgesellschaft AG · DE

Inventors

• Horst Gehmecker · Hofheim, DE
• Werner Rausch · Hopewell Junction, US
• Peter Schubach · Nidderau, DE

Key dates

• Filing date: Sep 22, 1992
• Grant date: Dec 7, 1993
• Expiry date: Sep 22, 2012

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C23C22/368
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

In a process of phosphating metal surfaces phosphating solutions are employed which are substantially free of nickel and contain ______________________________________ 0.3 to 1.7 g/l Zn 0.2 to 4.0 g/l Mn 0.001 to 0.030 (preferably 0.003 to 0.020) g/l Cu 5 to 30 g/l phosphate (calculated as P.sub.2 O.sub.5) ______________________________________ in which by oxygen and/or other equivalent oxidizers the concentration of Fe(II) is kept below 0.1 g/1 and which are adjusted to a pH value from 3.0 to 3.8. The weight ratio of Cu to P.sub.2 O.sub.5 is preferably adjusted to I: (170 to 30,000) and Cu and P.sub.2 O.sub.5 are preferably replenished in a weight ratio of 1 : (5 to 2000). The phosphating solutions should contain 0.3 to 1.0 g/1 Zn if they are applied by spraying and should contain 0.9 to 1.7 g/1 Zn if they are applied by spraying/dipping operations or by a dipping operation. The process serves particularly for the pretreatment of metal surfaces for a succeeding painting, particularly by electro-dipcoating, and for the phosphating of steel, galvanized steel, zinc alloy-plated steel, aluminum and its alloys.