Cathodic disbonding of self-healing composite coatings: effect of ethyl cellulose micro/nanocapsules

Abstract

ABSTRACT The effect of ethyl cellulose (EC) micro/nanocapsules containing linseed oil (LO) on the cathodic disbonding of self-healing composite coatings is investigated by cathodic disbonding test and electrochemical impedance spectroscopy (EIS). Results reveal that the presence of EC nanocapsules significantly improves the cathodic disbonding resistance of the coatings so that the rates of disbonded area under the simulated condition of cathodic protection decrease from 3.882 mm2 h for the blank coating to 0.025 mm2 h for the nanocapsules containing coating. It may be ascribed to the releasing LO and filling the defects at the coating/substrate interface by oxidative polymerisation mechanism. EIS test results indicate that the corrosion resistance of the coatings is improved in the presence of EC nanocapsules. In addition, the coating resistance to cathodic disbonding and corrosion increase by decreasing capsule sizes. Finally, a proposed mechanism of ion diffusion through the self-healing coating’s defect is schematically illustrated.