Application of impedance spectroscopy during the lifetime of organic coatings

In this paper the use of Electrochemical Impedance Spectroscopy is evaluated for three situations during the lifetime of organic barrier coating. These situations are: • Defect free coatings • Delaminated, but intact coatings • Coatings with defects combined with cathodic delamination It is shown that in the first case EIS is reduced to a dielectric study of the coating polymer. This study gives information on the technical lifetime of an intact coating. In the second case only a qualitative indication of the onset of delamination can be obtained. In the last case contributions of the pore and the corrosion product within the pore are measured. It is not possible to measure a delaminated area