The use of pre-treatments based on doped silane solutions for improved corrosion resistance of galvanised steel substrates

The present work aims at evaluating the corrosion resistance of galvanised steel substrates pre-treated with bis-[triethoxysilylpropyl] tetrasulfide silane doped with cerium nitrate or zirconium nitrate. The corrosion resistance of the pre-treated substrates was evaluated by electrochemical impedance spectroscopy, during immersion in NaCl solutions. The chemical composition of the surface was assessed by X-ray photoelectron spectroscopy and the surface morphology was studied by atomic force microscopy. The electrochemical results show that pre-treatments based on doped silane solutions provide good corrosion protection of the galvanised steel substrates. The work also aims at discussing the role of the dopants on the protective properties of the silane coatings formed on galvanised steel substrates.