The mechanism of inhibition by zinc phosphate in an epoxy coating

Epoxy coatings containing different volume fractions of zinc phosphate have been successfully prepared and their inhibitive properties have been studied by electrochemical impedance spectroscopy (EIS) and immersion tests. The results show that zinc phosphate can improve the protection ability of epoxy coatings and its best volume fraction is 30%. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) results indicate that the presence of zinc phosphate can form an inhibiting film which is composed of the phosphating film of FePO4, Fe2O3, and FeO, as well as the shielding film of zinc phosphate on the steel surface.

► Zinc phosphate has a corrosion inhibitive effect.
► The best concentration of zinc phosphate is 30 vol.%.
► Epoxy coating with zinc phosphate has self-healing function.