Performance evaluation of mercapto functional hybrid silica sol–gel coating and its synergistic effect with f-GNs for corrosion protection of copper surface

A nanocomposite coating comprising mercapto functional hybrid silica sol–gel coating and functionalized graphene nanoplates nanocomposite coatings with advanced anticorrosive properties was prepared by a sol–gel method. In this study, graphene oxide (GO) nanoplates were silanized using 3-aminopropyltriethoxysilane (APTES) to obtain functional graphene nanoplates (f-GNs). The f-GNs were characterized by FTIR, XRD, XPS, TEM, AFM and TGA techniques. The functionalized graphene nanoplates were chemically bonded to a sol–gel matrix and showed good dispersion in the sol. Then, silica hybrid sol–gel nanocomposites with raw GO and different amounts of f-GNs were applied on the copper surface. Uniform, defect-free and adherent sol–gel films were obtained. Various corresponding methods were used to investigate the nanocomposite coating's properties. The corrosion resistance of copper significantly improved after being coated with mercapto functional hybrid silica sol–gel. The addition of f-GNs to the mercapto functional silica sol–gel coatings further improved the corrosion resistance due to a synergistic effect. Moreover, with an increase in the amount of f-GNs in the nanocomposite coating, the nanocomposite showed improved corrosion resistance. The nanocomposite containing 0.1 wt% f-GNs can efficiently protect the copper substrate from corrosion. This improvement was primarily attributed to the homogeneous dispersion of the f-GNs in the silica gel matrix and their effective barrier against corrosive molecules and ions. However, adding raw GO or excess f-GNs to the silica hybrid sol–gel coating had a negative effect on the corrosion resistance.