Greatly enhanced corrosion/wear resistances of epoxy coating for Mg alloy through a synergistic effect between functionalized graphene and insulated blocking layer

The poor corrosion and wear resistances of Mg alloys seriously limit their potential applications in various industries. The conventional epoxy coating easily forms many intrinsic defects during the solidification process, which cannot provide sufficient protection. In the current study, we design a double-layer epoxy composite coating on Mg alloy with enhanced anti-corrosion/wear properties, via the spin-assisted assembly technique. The outer layer is functionalized graphene (FG) in waterborne epoxy resin (WEP) and the inner layer is Ce-based conversion (Ce) film. The FG sheets can be homogeneously dispersed within the epoxy matrix to fill the intrinsic defects and improve the barrier capability. The Ce film connects the outer layer with the substrate, showing the transition effect. The corrosion rate of Ce/WEP/FG composite coating is 2131 times lower than that of bare Mg alloy, and the wear rate is decreased by ∼90%. The improved corrosion resistance is attributed to the labyrinth effect (hindering the penetration of corrosive medium) and the obstruction of galvanic coupling behavior. The synergistic effect derived from the FG sheet and blocking layer exhibits great potential in realizing the improvement of multi-functional integration, which will open up a new avenue for the development of novel composite protection coatings of Mg alloys.