Analysis of the non-ideal capacitive behaviour for high impedance organic coatings

In this work, we propose a model to represent high impedance thick organic coatings constituted with a dry part of the coating, in contact with the substrate and a humid part in contact with the electrolytic solution. Water is assumed to be uniformly distributed in the humid part of the coating while a resistivity decrease is considered in the dry part. Finally, a Young impedance in series with a humid film (RC) constant is obtained and compared to experimental results.