Abstract
Fundamentals of an electrochemical impedance measurement were reviewed. The impedance characteristics under charge transfer control and under diffusion control, and their equivalent circuits are described. Analytical method using the Nyquist plot and the Bode plot for typical impedance spectra was explained. In addition, a change in impedance behavior for CPE (constant phase element) parameter, which is often used in equivalent circuit modeling and data fitting of electrochemical impedance data, was represented. In the latter of this paper, research reports for degradation estimation of steel materials used for infrastructure using an electrochemical impedance measurement were provided. The degradation of organic coated steels, the structure of thermally sprayed coating exposed to outdoors for a long term, and the corrosion performance of reinforcing steel bars in concrete were estimated by electrochemical impedance method.
