In-situ reduction enhanced waterborne graphene-based biomimetic coating based on a glutaraldehyde covalent bonding fixation strategy

Graphene-based materials have great application potential in Mg alloy surface protection, while traditional graphene-based waterborne coating has poor water-resistance stability. In this work, a reduced graphene oxide (RGO)/polyvinyl alcohol (PVA)/glutaraldehyde (GA) coating (RPG) with a “brick-and-mortar” structure was prepared on the surface of Mg alloys to achieve integrated protection against corrosion and wear. The synergistic effect of covalent bonding fixation and thermal reduction coupling enhanced the hydrophobicity and interface bonding of waterborne graphene-based coatings, thus improving the barrier effect and corrosion resistance of samples. Significantly, the incorporation of GA in the bionic structure improved the thermal stability and gap-filling effect of the coating through its covalent bonding fixation effect on RGO sheets, which decreased the micro-gaps and defects between layers caused by thermal expansion during in-situ thermal reduction. Furthermore, RPG coating has enhanced anti-wear ability after 170 °C heat treatment. The thermal removal of oxygen-containing functional groups contributed to improving surface lubricity, although the covalent bonding fixation effect constrained the low shear relative slip between RGO sheets. This study would provide guidance for the bionic construction of waterborne graphene-based coatings with integrated corrosion and wear resistance.