Controlled oxidation of mild steel by potassium permanganate solution to enhance protective functioning of silane coatings

The influence of potassium permanganate in the surface treatment solution on the protection of subsequent silane film was assessed using surface analysis and electrochemical methods. In order to formulate the treatment solutions, several concentrations of KMnO4 up to 200 ppm were added to a diluted sulfuric acid solution. The scanning electron microscopy (SEM/EDS), atomic force microscopy (AFM), water contact angle, grazing X-ray diffractometry (GXRD), electrochemical impedance spectroscopy (EIS) and polarization measurements were employed to obtain the optimal content of KMnO4 in sulfuric acid solution. It was shown that controlled surface oxidation of mild steel at the optimal concentration of KMnO4, 100 ppm, increased the subsequent organosilane layer protective functioning against corrosion attacks.