Impedance monitoring of corrosion degradation of plasma electrolytic oxidation coatings (PEO) on magnesium alloy

Impedance technique based on continuous multisinusoidal current perturbation was used to explain degradation process of plasma electrolytic oxidation coatings (PEO) on magnesium alloy. An obtained impedance spectrum was fitted by electrical equivalent circuit to describe properties of conversion layer on magnesium alloy. Additionally, galvanostatic mode maintained during experiment, with DC current equal to zero, allowed to achieve corrosion potential in degradation process. This methodology has advantage over more conventional methods. It allows observing parameters change in function of time and explanation of the degradation process of PEO on magnesium alloy.