Different approaches in evaluating organic paint coatings with electrochemical impedance spectroscopy

This work presents the effectiveness of different approaches in evaluating two coatings with intermediate and poor qualities using electrochemical impedance spectroscopy (EIS) measurements. Different approaches with no errors in calculations, i.e. the breakpoint frequency, changing rate of impedance, impedance at low frequency, phase angle at high frequency, and the areas under Bode plots were used in evaluating coated samples with EIS measurements. Results from these approaches were compared with each other and with the results extracted from the equivalent electrical circuit (EEC) models. The results are in good agreement with EEC models in coating ranking point of view. It is found that the results of impedance at low frequencies, breakpoint frequency, and Bode area measurements were useful in evaluating coating performance during immersion period.