Process for phosphating metal surfaces

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 P2O5) - in which by oxygen and/or other...

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Bibliographische Detailangaben
Hauptverfasser: RAUSCH, WERNER, SCHUBACH, PETER, GEHMECKER, HORST
Format: Patent
Sprache:eng
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Zusammenfassung: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 P2O5) - 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 P2O5 is preferably adjusted to I: (170 to 30,000) and Cu and P2O5 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.