Analysis of chemical compositions and morphology of surface films formed on 3003 aluminum alloy by immersion in different cation containing model tap waters

The effect of metal cations, Na+, K+, Ca2+, Mg2+, Zn2+, and Ni2+, on oxide film structure and morphology changes during immersion corrosion tests of 3003 aluminum alloy in model tap waters was investigated by surface analysis techniques including Auger electron spectroscopy (AES), X‐ray photoelectron spectroscopy (XPS), and scanning electron microscopy. The hardness of metal cations based on the hard and soft acids and bases (HSAB) concept was applied to explain the effect on the passive oxide film structure. Numerous nano‐sized pits were observed after 86.4 ks immersion in model tap water, and nano‐sized corrosion products were also observed especially in specimens immersed in K+ containing solutions. The AES and XPS results showed that hard metal cations like Zn2+ and Ni 2+ were included in the oxide films, while soft metal cations were not included in the oxide films. The results are in good agreement with those which could be expected from the HSAB hardness of the metal cations. Copyright © 2013 John Wiley & Sons, Ltd.