Method for nickel-free phosphating metal surfaces
AssigneeChemetall GmbH
InventorsOlaf Dahlenburg, Thomas Kolberg, Lisa Seider
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Abstract
The present invention relates to a method for substantially nickel-free phosphating of a metallic surface, wherein a metallic surface is treated one after the other with the following compositions: i) with an alkaline, aqueous cleaner composition which comprises at least one water-soluble silicate, and ii) with an acidic, aqueous, substantially nickel-free phosphating composition which comprises zinc ions, manganese ions and phosphate ions. The invention also relates to the above cleaner composition itself and also to a metallic surface phosphate-coated by the above method, and to the use of said surface.
Claims16
A method for substantially nickel-free phosphating of a metallic surface, which comprises treating a metallic surface one after the other with the following compositions:
- i) with an alkaline, aqueous cleaner composition which comprises at least one water-soluble silicate, the at least one water-soluble silicate comprising at least one waterglass and/or at least one metasilicate, the at least one water-soluble silicate being present in a total concentration in the range from 0.01 to 15 g/l, the at least one water-soluble silicate having a water-solubility of at least 1 mg/l in deionized water at 25° C., the pH of the cleaner composition being in the range from 10.7 to 12.0, and then
- ii) with an acidic, aqueous, substantially nickel-free phosphating composition which comprises zinc ions, manganese ions and phosphate ions and less than 0.01 g/l nickel ions;
- and
- iii) with an aqueous after-rinse composition after treating the metallic surface with the phosphating composition, the after-rinse composition comprising molybdenum ions and zirconium ions.
Dependencies are inferred from the claim text.