The effect of Zn2+ concentrations on the formation of zinc phosphate conversion coatings
(ZPCCs) on Al-Mg-Zn alloy was investigated. The morphology of the coatings was studied by
scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion resistances of
the coated and uncoated samples were evaluated by open circuit potential and potentiodynamic
polarization techniques. The results revealed that the conversion coating consists of hopeite as a
single phase. Furthermore, the results indicated that the corrosion resistance of the coated Al-Mg-
Zn samples was found to increase with increasing Zn2+ concentration.