Incorporation of graphene oxide to achieve enhanced anti-corrosion performance of epoxy powder coatings

Organic coatings are among the cost-effective and widely used anti-corrosion materials. In this study, twodimensional graphene oxide (GO) sheets with an average diameter of approximately 5 mu m and a thickness of about four layers were successfully prepared. GO/epoxy composite powder coatings (GO/EP) with varying GO concentrations were fabricated via melt extrusion and subsequently electrostatically sprayed onto carbon steel substrates. The long-term anti-corrosion performance of the GO/EP coatings was systematically investigated. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests revealed that, compared with the neat EP coating, the GO/EP composite coating containing 0.2 wt% GO exhibited a three-order-ofmagnitude increase in low-frequency impedance modulus and a three-order-of-magnitude decrease in corrosion current density. Pull-off adhesion tests conducted after neutral salt spray exposure demonstrated that the adhesion strength of the GO/EP composite coating was significantly improved. This enhancement can be attributed to the abundant oxygen-containing functional groups on GO sheets, which promote the ring-opening reaction of epoxy molecules, facilitate the curing reaction, and partially participate in cross-linking reactions with epoxy or curing agent molecules. Consequently, the structural density and impermeability of the cured coatings were significantly improved. Furthermore, the two-dimensional GO sheets exhibited excellent physical barrier properties, effectively reducing coating defects and inhibiting the penetration of corrosive media.