Low-temperature induced enhancement of corrosion/wear resistance in inverse nacre-like graphene-based waterborne coatings

The poor corrosion resistance of Mg alloys severely limits their industrial application. In this work, an inverse nacre-like waterborne coating composed of polyvinyl alcohol/glutaraldehyde (PVA/GA) and graphene oxide/glutaraldehyde (GO/GA) was prepared on Mg alloys. The in-situ heat treatment was applied to reduce hydrophilic transport channels within the bonding network and multilayer GO. The hydrophobicity of RGO sheets was increased owing to the thermal removal of oxygen-containing functional groups. Meanwhile, the heat-treated PVA/GA enriched with acetal linkage network performs “interlock effect” between the reduced graphene oxide/glutaraldehyde (RGO/GA) layers, inhibiting the interface delamination. Therefore, the thermally reduced graphene-based waterborne coating exhibited stable maze effect with extended hydrophobic barrier path. Besides, the low shear coordination of PVA/GA and RGO/GA weakened the contradictory relationship between the relative slipping and bonding strength of GO/RGO sheets, which effectively decreased the wear rate of samples, forming mechanical durability protection for the substrate. Therefore, the coating exhibits integrated corrosion/wear protection performance.