LEIS study of the protection of zinc phosphate/epoxy coatings under cathodic protection

Abstract

The anti-corrosion properties of the defective zinc phosphate/epoxy coatings under cathodic protection (CP) in a 3.5% NaCl solution were evaluated by localized electrochemical impedance spectroscopy (LEIS), scanning electrochemical microscopy and X-ray diffraction. The results revealed that the application of CP inhibited the formation of the phosphate film, compared with exposure at open circuit potential (OCP). Moreover, a CP/OCP cycle was beneficial to form a phosphate film on the defective coatings, particularly under a −0.65 V/OCP cycle. The mechanism of zinc phosphate modifying the corrosion process of the defective coatings under different cathodic potentials was also considered.