Anti-Corrosion Performance of Epoxy Coating Modified on the Surface of X80 Pipeline Steel in Dry-Wet Alternate Environment

The epoxy coating for bridge was modified by imidazoline corrosion inhibitor. The corrosion protection effect of modified coating on X80 pipeline steel in marine dry-wet alternate environment was studied by simulated corrosion test and electrochemical test. The results showed that with the increase of corrosion inhibitor content, the overall corrosion rate and maximum corrosion pit depth of X80 steel substrate decreased rapidly at first and then decreased slowly. The obvious hole phenomenon on the coating surface gradually weakend and gradually transformed into stratification characteristics. The degree of pitting corrosion of the metal substrate gradually reduced, and the corrosion position corresponded to the hole position of the coating. With the increase of corrosion inhibitor content, the corrosion potential increased, the free corrosion current density decreased, the double layer capacitance decreased, and the charge transfer resistance increased. The role of corrosion inhibitor in the coating mainly included increasing the crosslinking density of the coating and consuming the anions in the corrosive medium.