Voestalpine Stahl Gmbh

Gerald Luckeneder

Karl-Heinz Stellnberger

Christian Karl Riener

Edmund Holzer

Josef Hagler

Daniel Roman Fritz

Harald Haslinger

Franz Priewasser

Siegfried Wiesinger

A method for surface-treating a metallic substrate, in particular steel plate, using a protective coating on a Zn basis, according to which a chloride-containing solution is applied to the protective coating and as a result an anti-corrosion layer comprising hydrozincite and simonkolleite is formed at least in parts. To increase the corrosion resistance of the protective coating and to improve the process sequence and reproducibility of the method, the invention proposes reacting the protectively coated substrate with the solution which, using an acid, is adjusted to a pH of 4 to 6 and contains 1.8 to 18.5% by weight chloride, so as to increase the proportion of simonkolleite in relation to the proportion of hydrozincite in the anti-corrosion layer.

Method for surface-treating a metallic substrate

A method for improving the adhesive capacity of a protectively coated steel sheet is proposed, in which, in a continuous process, a protective coating based on Zn&#x2014;Al&#x2014;Mg is applied to the steel sheet and, in a further step, the protective coating undergoes a surface treatment in which an aqueous composition is applied in order to modify the natural oxide layer, which contains AlOand MgO, without pickling this natural oxide layer as a result. In order to significantly increase adhesive capacity of the protectively coated steel sheet, the invention proposes skin-pass rolling the protectively coated steel sheet and then reacting the natural oxide layer with an aqueous fluoride-containing composition, reducing its MgO content in order to thus modify the natural oxide layer.

Method for improving adherence

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Pinsdorf, Austria

Gerald Luckeneder