Corrosion resistance of hot dip galvanized steel pretreated with bis-functional silanes modified with nanoalumina

The corrosion behavior of hot dip galvanized steel pretreated with bis-[triethoxy-silylpropyl] tetrasulfide (BTESPT) modified with alumina particles was studied. The corrosion resistance of the passiving films was evaluated by Tafel polarization curve and electrochemical impedance spectroscopy. The films formed on the galvanized steel substrate were characterized by Fourier transform infrared spectroscopy and energy dispersive X-ray spectrometry. The surface morphology of the treated hot dip galvanized steel samples was observed by Field Emission Scanning Electron Microscope. The results show that the pretreatments on the basis of silane films modified with nanoalumina particles have reduced both anodic and cathodic current densities, and increased total impedance in the measured frequency, consequently, improving corrosion protection for hot dip galvanized steel during immersion in NaCl solutions compared to chromate films and silane films.