Simultaneously improved corrosion/wear resistances of epoxy coating on Mg alloy via the coupled hybridization of GO and nano-SiO2

The extensive application of Mg alloys is restricted by their poor corrosion, wear resistances and long-term service performance. Although the low-cost epoxy (EP) coating has excellent corrosion resistance , many pores and cracks are easily formed during the curing process, leading to the deterioration of barrier capacity. This study reports an epoxy-based nanocomposite coating, fabricated through the hybridization of γ-(2, 3-epoxypropoxy) propytrimethoxy silane modified silica nanoparticles and graphene oxide (mSiO 2 /GO). The insulating SiO 2 particles can isolate the direct contact between Mg alloy substrate and GO sheets, avoiding the formation of micro-cells and preventing the galvanic corrosion . The SiO 2 /GO in EP coating with “crack pinning and bridge” structure has reduced porosity and enhanced consistency, which effectively prevents crack propagation and electrolyte penetration. The corrosion rate of SiO 2 /GO/EP coating is 374 and 10 times lower than that of pure EP coating and individual GO/EP coating, respectively. The wear rate of GO/EP and SiO 2 /GO/EP coating specimens is 81.2 % and 70.4 % less than that of the pure EP coating, which is related to the favorable lubricating performance and high hardness of GO nanosheets . The results show that the embedding of well-distributed mSiO 2 -GO hybrids can remarkably improve the barrier effect and anti-corrosion of EP coating.