GALVANIZED ALUMINIUM SHEET

摘要

In a method for applying a zinc layer onto an aluminium or aluminium alloy sheet, comprising pretreating the surface and applying the layer by electrolytic galvanizing, the pretreating comprises electrochemical graining of said surface, for example in a solution having a pH less than 3 with an alternating current applied between the sheet and an electrode. In an alternative method, the pretreating includes applying a preliminary zinc layer by immersing the surface in a zinc-containing alkaline solution, applying a potential to the sheet and reversing the polarity of said potential at least once. The sheets are useful as for example building cladding sheets and automotive panels.