Increase in corrosion resistance of Zn–22Al–2Cu alloy by depositing an Y2O3 film studied by Auger electron spectroscopy

Thin films of Y2O3 were deposited on the surface of a zinalco alloy (Zn–22Al–2Cu) in order to modify the surface and increase the corrosion resistance. By means of ion sputtering and surface analysis using Auger electron spectroscopy, in-depth relative elemental intensity profiles were obtained. The growth mechanism of the surface oxides layer is modified by the deposited yttrium oxide film. On samples without film, corrosion progresses mainly at the surface as indicated by the zinc excess, while on samples with film, the growth of the oxides layer occurs at inner points of the film where migrating anions and cations are allowed to find each other. The growth of the corrosion products layer is about nine times smaller in samples with a film of 1600 Å of Y2O3 with respect to samples without a film. Migration of aluminum particles is higher than that of zinc particles, producing a surface highly enriched in aluminum.