X-ray photoelectron spectroscopy investigations of zinc–magnesium alloy coated steel

The coating layer composition depth profiles and element chemical states of zinc–magnesium alloy coated steel were investigated by X-ray photoelectron spectroscopy depth profiling. Through the analysis of photoelectron signals and Auger signals of different elements on different depth planes of the coating layer, it can be found that the surface of the coating layer contains MgCO3, MgO, Mg(OH)2, metallic Mg, metallic Zn and some complex zinc compounds. Under the surface, there is a Zn2Mg alloy layer with the thickness of about 300 nm accompanied with MgO and Mg(OH)2 in the layer. There is a transitional layer with the thickness of about 200 nm between the Zn2Mg alloy layer and the pure Zn layer, whose components consist of zinc–magnesium alloy without fixed stoichiometry, a little MgO and a little Mg(OH)2.