Corrosion behavior of organically modified silicates coatings

Purpose - The purpose of this paper is to develop hybrid organic-inorganic silica-based nanocomposite films, by sol-gel method, for corrosion protection of AA2024 alloy. Also, cerium nitrate corrosion inhibitor is introduced into the optimized coating in the next step of the investigations in order to study the improvement in the corrosion protection properties of the organically modified silicate (Ormosil) films. Design/methodology/approach - The sol-gel films have been synthesized from 3-glycidoxypropyltrimethoxysilane and tetraethylorthosilicate precursors. In order to investigate the effective factors on the properties of Ormosils films, different coatings with different organic and hydrolysis water content were developed. Then, cerium nitrate corrosion inhibitor was added to the coatings. The structure of the hybrid sol-gel films was studied by scanning electron microscopy. The corrosion protection properties of the films were studied by potentiodynamic scanning, and electrochemical impedance spectroscopy, respectively. Findings - The results indicate that the hybrid films provided exceptional barrier and corrosion protection in comparison with untreated aluminium alloy substrate. Moreover, improvement of the protection properties of the films containing cerium nitrate corrosion inhibitor occurred with immersion time. This would imply that cerium ions could reach the defects, and reduce the corrosion rate. Originality/value - This paper provides the development of Ormosils coating, which exceptionally improves the corrosion protection of 2024 aluminium alloy.