Corrosion protection evaluation of silica/epoxy hybrid nanocomposite coatings to AA2024

Silica-based organic–inorganic hybrid nanocomposite films have been developed by sol–gel method for corrosion protection of AA2024 alloy. The sol–gel films have been synthesized from 3-glycidoxypropyltrimethoxysilane (GPTMS) and tetraethylorthosilicate (TEOS) precursors. Interlinked organic–inorganic networks can be formed because of the presence of both epoxy and silicon alkoxide functionalities in the precursor molecules. In order to investigate the effective factors on the properties of organically modified silicates films (Ormosils), different coatings with different organic and hydrolysis water content were developed. The films were prepared by dip-coating technique. The chemical composition and the structure of the hybrid sol–gel films were studied by energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM), respectively. The corrosion protection properties of the films were studied by potentiodynamic scanning (PDS) and salt spray tests. The results indicate that the hybrid films provided exceptional barrier and corrosion protection in comparison with untreated aluminium alloy substrate.