Epoxy coating capable of providing multi-component passive film for long-term anti-corrosion of steel

CeO 2 -PANI conductive polymer capsules were prepared by in-situ chemical oxidation polymerization. The capsules were dispersed in F51 epoxy resin and then sprayed onto the steel surface to form novel coatings after curing. The corrosion resistance of coatings was investigated by EIS in a 3.5 wt% NaCl solution. After 30 days, the 60-μm-thin coating containing CeO 2 -PANI capsules exhibited the highest corrosion resistance, and its impedance modulus was higher than 10 9 Ω·cm 2 , which was 10 times that of conventional PANI-Epoxy coatings. This improvement was attributed to the (Fe 3 O 4  + γ-Fe 2 O 3  + CeO 2 ) passive film actively formed by the synergistic effect of PANI and Ce 3+ ions. PANI polarized the anodic reaction and Ce 3+ inhibited the cathodic reaction.