About coatings and cathodic protection: Properties of the coatings influencing delamination and cathodic protection criteria

Two aspects related to the deterioration process of organic coated structures under cathodic protection, detected in a previous work, are analysed: (i) why the size of failures exposing the metallic substrate can influence the level of delamination and (ii) if there is a failure exposing the metallic substrate, why the appearance of blisters is fostered even away far from the original failure, The results show that an improvement of laboratory procedures for coatings selection can contribute to the development of coating/cathodic protection technology. Finally, the limitations of usual cathodic protection criteria are discussed considering the impedance measurements of samples with electrodes placed at the coating/metal interface. (C) 1998 Elsevier Science Ltd. All rights reserved.