Corrosion protection of AA2024-T3 by sol-gel film modified with graphene oxide

Graphene oxide (GO) was introduced into sol-gel systems to enhance the corrosion protective properties of the obtained film on AA2024-T3 aluminum alloy. The characterization of morphology, microstructure and component of the films indicated that GO covalently reacted with silanol groups from hydrolyzed 3-glycidoxypropyl-trimethoxysilane (GPTMS) monomer, forming silane functionalized GO (SGO) by COSi covalent bonds. Corrosion protective properties of the films were evaluated through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and immersion tests studies. The results showed that the addition of GO improved the corrosion protective properties of sol-gel film distinctly by providing the good barrier property of layered GO and enhancing the cross-linking density of the film. The significant improvement of GO on sol-gel film mainly focused on the resistance and capacitance of film itself. The optimal concentration of GO addition was 0.5 mg mL−1, at which the film was uniform and showed good corrosion protective properties in 0.05 M NaCl aqueous solution. The corrosion current density of the sol-gel film with 0.5 mg mL−1 GO was one order magnitude smaller than that of sol-gel film without GO. The protection efficiency of the film was up to 99.45%.