XPS study of the surface chemistry of conventional hot-dip galvanised pure Zn, galvanneal and Zn–Al alloy coatings on steel

This study uses X-ray photoelectron spectroscopy (XPS) to analyse the outer surfaces of galvanised, galfan and galvanneal metallic coatings obtained by hot dipping. Considerable aluminium segregation towards the surface, principally as Al2O3, has been seen in all the studied coatings. The aluminium content on the surface was surprisingly similar to or even greater than the zinc content, which is the major element in the chemical composition of these coatings. The formation of Al2O3 seems to prevent the oxidation of the zinc in the metallic coating.