Electrochemical impedance spectroscopy as a valuable monitoring technique for various forms of corrosion

Abstract

Even with many fundamental advantages over other electrochemical techniques, electrochemical impedance spectroscopy remains difficult to use for field corrosion monitoring. In order to bridge the gap between the crude world of field corrosion testing and carefully planned laboratory experiments involving sophisticated instrumentation and expertise, a few simplifications are required. A reduction in the instrumental complexity of this technique can be achieved by firstly optimizing the number of frequencies needed to perform valid measurements. The statistical validation of an RC model from a limited number of data points can be achieved by systematically permutating the three data points which are chosen to extrapolate the centres of semicircular impedance diagrams. Typical results obtained with various systems (Cu-Ni against sea water, carbon steel against inhibited or uninhibited electrolyte) are presented and discussed.