Nickel-free phosphating process
AssigneeHenkel Kommanditgesellschaft auf Aktien
InventorsWolf-Achim Roland, Karl-Heinz Gottwald, Matthias Hamacher, Jan-Willem Brouwer
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Abstract
The invention is a process for applying a nickel-free, copper-containing phosphate coating to a metal surface by contacting the metal surface with a phosphate solution containing 0.2 to 2.0 g/l zinc ions, 0.5 to 25 mg/l copper ions, and 5-30 g/l phosphate ions.
Claims18
A process for the production of copper-containing nickel-free phosphate coatings with a copper content of 0.1 to 5% by weight and an edge length of the phosphate crystals of 0.5 to 10 μm on a metal surface selected from the group consisting of galvanized steel and alloy-galvanized steel which comprises contacting the surface with a phosphating solution containing:
- a) zinc ions 0.2 to 2 g/l;
- b) copper ions 0.5 to 25 mg/l;
- c) phosphate ions 5 to 30 g/l (expressed as P2O5);
- d) at least one member selected from the group consisting of hydroxylamine salts, hydroxylamine complexes and hydroxylamine in a quantity of 500 to 5,000 ppm of hydroxylamine, based on the phosphating solution;
- and
- e) manganese ions 0.1 to 5 g/l;
- said phosphating solution being substantially free of nitrite ions.
Dependencies are inferred from the claim text.