Electrochemical evaluation of zinc and magnesium alloy coatings deposited on electrogalvanized steel by PVD

Zinc alloy coating attracted much attention due to its high anti-corrosive properties. Particularly, zinc alloy coatings containing magnesium was considered a promising metallic alloy due to a remarkable improvement of corrosion resistance. The proper magnesium content for Zn–Mg alloy coatings was studied. The samples were prepared using thermal evaporation method. The influence of Zn–Mg alloy coating on corrosion resistance was evaluated using immersion test, potentiodynamic test, and galvanic test in 3% NaCl solution at room temperature. The results show that the corrosion resistance of Zn–Mg alloy coatings is strongly dependent on magnesium content. Corrosion potential decreases with increasing magnesium content, whereas current density increases up to 15% magnesium content, and passivity region was found only in Zn–Mg coatings.