Effect of graphene on the microstructure and corrosion resistance of PEO coating formed on D16T aluminum alloy

Incorporated graphene coating was successfully prepared on D16T aluminum alloy by plasma electrolytic oxidation (PEO) technology, and the effect of graphene on the microstructure, corrosion resistance, and wettability of the coating was investigated. Microstructure, composition, and morphology were studied by transmission electron microscope, confirming that graphene was successfully incorporated into the coating with pancake-like and embedded mode. The thickness and microhardness of the coating with graphene (G2) increased, whereas roughness and porosity reduced due to the incorporation of graphene, compared to the coating without graphene (G0). The resistive arc radius of G2 is obviously increased. The real impedance value of G2 is four times than that of G0. The resistance (R-1) of G0 and G2 are 3708 and 7533 omega cm(2), respectively. The resistance (R-2) of G0 and G2 are 2.508E5 and 7.752E5 omega cm(2), respectively. The contact angle of G2 under three liquid droplets was maximum, showing minimal surface-free energy (36.8 mJ/m(2)). Formation water showed the most obvious effect on the wettability of the coating compared to the distilled water and sodium chloride solution. Results verified that graphene in PEO coating significantly improved the microstructure of the coating and enhanced the hydrophobic performance and corrosion resistance of the coating.