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

Abstract

AbstractThe 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 × 105 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.