Siloxane-based thin films for corrosion protection of stainless steel in chloride media

The corrosion protection of stainless steel (SS 316L) provided by layers of SiO(2) and by siloxane-anchored self-assembled monolayer (SAMs) was assessed by cyclic voltammetry (CV) and by potentiostatic current transient in sodium chloride media. The SAMs were composed of octadecyltrimethoxysilane anchored onto a thin (1-2 nm) layer of SiO(2). The initial SiO(2) layer was obtained by treatment with tetraethoxyorthosilicate. Successive layers were added by applying the alkylsiloxane and then oxidatively removed by treatment using a UV-ozone cleaner. Though SAMs have been used as corrosion barriers in other contexts, it is shown that successive cycles of SAM deposition and ablation provide an extended SiO(2) thin-covering layer that protects stainless steel against pitting and general corrosion.