Corrosion resistance and electrical conductivity of V/Ce conversion coating on magnesium alloy AZ31B

A conversion coating with both corrosion resistance and electrical conductivity on magnesium alloy AZ31B was prepared by V/Ce conversion solution containing transition metal salt and formed compact coating with hemispherical particles. The application of potentiostatic polarization test and electrochemical impedance spectroscopy (EIS) is for the evaluation of the corrosion resistance of coatings. Compared with AZ31B magnesium alloy, the corrosion current density of the conversion coating is decreased by two orders of magnitude. The total impedance of the V/Ce conversion coating rose to 1.6 × 10³ Ω·cm² in contrast with 2.2 × 10² Ω·cm² of the bare AZ31B. In addition, the electrical conductivity of the coating was assessed by conductivity meter and Mott-Schottky measurement. The results reveal a high dependence of the conductivity of the coating and the semiconducting properties of the coating compositions.