Initial formation of corrosion products on pure zinc and MgZn2 examinated by XPS

A corrosion behaviour study of pure phases of zinc and zinc-magnesium (MgZn2) exposed to humid air at 35 degrees C for 4 days is presented. For zinc, hydroxide formation at the surface and zinc oxide in the first inner-layers is observed. The corrosion of the MgZn2 leads to the segregation of magnesium at the surface to mainly form magnesium hydroxycarbonate: the presence of magnesium modifies the corrosion products. At larger depths, metallic zinc coexists with magnesium oxide and hydrozincite. The higher reactivity of MgZn2 alloy can be attributed to the interaction with carbonate ions. (C) 2013 Elsevier Ltd. All rights reserved.