Effect of Temperature and Applied Potential on Cathodic Disbonding Performance of Epoxy Coating with Second Generation of Phosphate-based Anticorrosion Pigment

The incorporation of anticorrosion pigments into the coating formulation is one of the most effective approaches to enhance the resistance against cathodic disbonding. Accordingly، new generations of phosphate-based anticorrosion pigments could be used to improve inhibition efficiency of zinc phosphate pigment as a conventional alternative to toxic chromates. In addition to studying the role of zinc aluminum phosphate، which represents the second generation of phosphate-based anticorrosion pigments in the protective performance of an epoxy-polyamide coating through electrochemical noise method، this paper intends to investigate the effect of the modification of zinc phosphate pigment on the resistance to cathodic disbonding. In the presence of the modified pigment، the improved adhesion strength and decreased disbonding rate were connected to local pH control in the disbonding front and the precipitation of a protective layer، confirmed by electrochemical impedance spectroscopy parameters. Although elevated temperature and more cathodic potential accelerated coating disbondment، zinc aluminum phosphate still revealed superior performance in strengthening the adhesion between the anticorrosive coating and steel substrate and enhancing the resistance against cathodic disbonding.