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In this work, a novel evaluation strategy for the X-ray photoelectron spectroscopy (XPS) chemical assessment is proposed to identify the corrosion products formed on the surface of hot-dip galvanized ZnMgAl coatings after exposure to standardized salt spray tests. The experiments demonstrate that the investigated system exhibits a problematic differential charging behavior between the different compounds, an effect which cannot be fully compensated for by the flood gun of the XPS system, making a reliable evaluation of the individual spectra impossible by using standard evaluation and fitting methods. For that reason, a new effective approach--taking the different charge shifts into account--was implemented and its reliability experimentally verified on model mixtures of assumed corrosion products with known composition. With this new approach, the chemical surface composition of an industrial sample of a corroded ZnMgAl coating was revealed and discussed in order to clearly demonstrate the potential of the proposed method for future corrosion studies.

In this work, three different hot-dip galvanizing alloys ZnAl0.2, ZnAl5, and ZnAl2Mg2 were tested in non-standardized salt spray tests. In those nonstandardized salt spray tests, samples were exposed to different pH values, calcium and magnesium ions. The corrosion products formed on the alloys in different conditions were analyzed with XRD and Raman spectroscopy. Additionally, the corrosion behavior of the samples was investigated by studying cross-section cuts with SEM. By analyzing the corrosion products formed on different samples a theory about the beneficial effect of magnesium in terms of corrosion behavior was developed.