Improvement of the corrosion performance of 304L stainless steel by a nanostructure hybrid coating/henna extract

Purpose - The purpose of this investigation was to study the corrosion protection and structural characteristics of a hybrid organic-inorganic thin film preloaded with green corrosion inhibitor for anticorrosive protection of stainless steel 304L. Design/methodology/approach - An ethanol solution of the polymerized 3-methacryloxypropyltrimethoxysilan and tetraethylorthosilicate was mixed with henna extract to give homogeneous sols. The morphology, composition and adhesion of hybrid sol-gel coatings were examined by SEM, EDX and pull-off tests, respectively. The surface chemistry of the hybrid sol-gel coatings was investigated with polarization scans and electrochemical impedance spectroscopy (EIS) in the physiological saline solution. Findings - The polarization curves and EIS data were in agreement. Henna extract additions significantly increased the corrosion protection capability of the sol-gel thin film to greater than 85 percent in the physiological saline solution. In addition, the doped hybrid coating on stainless steel 304L was useful in 3.5 percent NaCl solution. Originality/value - There have been few reports on the hybrid organic-inorganic thin films preloaded with corrosion inhibitor, as described in the paper, and this environmentally friendly coating on stainless steel 304L was found to be highly effective for industrial applications.