On the Choice of Equivalent Electrical Circuits for the Aluminum Alloys Oxide Coatings Studies by Electrochemical Impedance Spectroscopy

This paper reviews research on the application of equivalent electrical circuits (EEC) for extracting electrochemical parameters of the aluminum alloys oxide coatings. Based on the published research and experimental data gathered by authors we conclude that the most common EEC, applicable to nonsealed coatings and coatings with different sealing, is dual-circuit, consisting of two parallel connected resistors and constant phase elements (CPE). When corrosion damage is introduced the circuit can still be applied except for sufficient degradation of the surface, in which the total impedance is dominated by the double capacitance layer and the impedance can be modeled by the Randles circuit.