Bio-inspired graphene oxide/epoxy coating with ordered stacking for anticorrosion/wear protection of Mg alloy

The random arrangement of graphene oxide (GO) nanosheets within the organic coating forms a conductive network, thereby accelerating galvanic corrosion and exacerbating metal deterioration. Inspired by ordered layered structure of natural nacre, this study has successfully fabricated a biomimetic GO/epoxy coating on Mg alloy to prevent corrosion and reduce wear. By polymerizing polyaniline (PANI) and dopamine (PDA) on the GO, GO/PANI/PDA sheets with good dispersibility and impermeability are obtained. Subsequently, the bio-inspired coating (I-GO/PANI/PDA-WEP) with “nacre-like” structure is prepared via alternately spraying GO/PANI/PDA layers with epoxy layers. The anisotropic electrical conductivity of the coating is derived from the ordered distribution of GO/PANI/PDA layers to the Mg substrate, which can conduct electricity more efficiently in-plane while suppressing longitudinal electron transport. The enhanced physical barrier effect by the “nacre-like” structure and the electron suppression effect can improve anticorrosion performance. The coating reduces the corrosion rate by 6.3 × 10 5 times in comparison to Mg alloy. Moreover, this coating shows excellent wear resistance, which protects Mg alloy from friction and wear with a reduction in wear rate by approximately 96%. This bio-inspired approach offers a unique strategy for fabricating GO composite coatings with exceptional performance. Highlights The corrosion/wear resistance of I-GO/PANI/PDA has greatly improved. GO/PANI/PDA coating exhibits excellent anisotropic conductivity. Galvanic corrosion is inhibited due to the addition of GO/PANI/PDA. “Nacre-like” structure shows high labyrinth effect. The ordered orientation of GO/PANI/PDA suppresses out-plane electron transport.