Application of electrochemical impedance spectroscopy to study the degradation of polymer-coated metals

The recent widespread application of electrochemical impedance spectroscopy (EIS) to study the degradation of polymer-coated metals has been reviewed. The availability of modem instrumentation to obtain impedance data as well as computer programs to interpret the results have made the technique popular. In addition, EIS is very suited to the study of polymer-coated metals. However, despite, and even because of sophisticated methods of interpretation, some of the conclusions made in EIS studies remain questionable. A proliferation of equivalent circuits has been postulated without however confirmation by other experimental techniques. The significance and the reliability of different parameters obtained from EIS and used as criteria of coating deterioration remain controversial despite the large number of studies carried out. EIS has also been used, with limited success, to monitor in situ the degradation of polymer-coated metals in atmospheric exposure.