An electrochemical method for evaluating the resistance to cathodic disbondment of anti-corrosion coatings on buried pipelines

Methods for evaluating the resistance to cathodic disbondment (RCD) of anti-corrosion coatings on buried pipelines were reviewed. It is obvious that these traditional cathodic disbondment tests (CDT) have some disadvantages and the evaluated results are only simple figures and always rely on the subjective experience of the operator. A new electrochemical method for evaluating the RCD of coatings, that is, the potentiostatic evaluation method (PEM), was developed and studied. During potentiostatic anodic polarization testing, the changes of stable polarization current of specimens before and after cathodic disbonding (CD) were measured, and the degree of cathodic disbondment of the coating was quantitatively evaluated, among which the equivalent cathodic disbonded distance ΔD was suggested as a parameter for evaluating the RCD. A series of testing parameters of the PEM were determined in these experiments.