Homogeneously Dispersed Graphene Nanoplatelets as Long-Term Corrosion Inhibitors for Aluminum Matrix Composites

Deformation-driven metallurgy was implemented to prepare graphene nanoplatelet (GNP)-reinforced aluminum matrix composites with a time-dependent self-enhancement in corrosion resistance. Severe plastic deformation contributed to the sufficient brokenness, thinning, enfolding, and redispersion of GNPs, as well as grain refinement. The homogeneously dispersed GNPs showed a great corrosion inhibition mechanism in a chloride-containing environment, ascribed to the formation of a carbon-doped protective film via diffusion and chemical bonding between GNPs and the surface oxide film. Electrochemical and intergranular corrosion tests were conducted to show the enhancement of long-term corrosion resistance. First-principles calculations were performed to explore the high corrosion resistance of the carbon-doped protective film. The energy barriers of vacancy formation, Cl ingress, and charge transfer were synchronously enhanced with the addition of GNPs into aluminum matrix composites as long-term corrosion inhibitors.