Silane modification of titanium dioxide-decorated graphene oxide nanocomposite for enhancing anticorrosion performance of epoxy coatings on AA-2024

Titanium dioxide-decorated graphene oxide nanocomposite (TiO2-GO) was synthesized with the help of 3-aminopropyltriethoxysilane (APS) and characterized by Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results revealed that TiO2 was decorated to GO by chemical bonds. Then TiO2-GO nanocomposite was modified with γ- (2,3-epoxypropoxy) propyltrimethoxysilane (GPTMS) before introducing into epoxy resin to form an epoxy coating (TiO2-GO-f-EP) on AA-2024 aluminum alloy for good anticorrosion properties. The scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, salty spray and UV aging measurements were carried out to confirm that the TiO2-GO-f-EP coating exhibited good anti-corrosion performance. The corrosion current density of TiO2-GO-f-EP coating was nearly two orders of magnitude lower than that of pure epoxy coating and the adhesion loss after UV aging test changed 86%–57%, compared with pure epoxy coating. The superiority of TiO2-GO-f-EP coating is related to the TiO2-GO addition which can enhance anti-UV aging performance of the epoxy coating and the GPTMS modification that may ensure TiO2-GO nanocomposite's good dispersion into epoxy resin and improve the cross-linking density and adhesion strength of the epoxy coating.