Corrosion resistance of galvanized steel post-treated with silane precursors tmspma and teos: Effect of immersion time in solution

Chromate layers present a excellent performance against the corrosion however, the process to obtain these kind of films have been abandoned due to the use of hexavalent chromium which is highly toxic and carcinogenic. An environmentally friendly alternative is the use of hybrid organic-inorganic layers. In this study, the galvanized steel was coated with a hybrid film obtained from a sol consisting of silane precursor 3 - (trimetoxisililpropil) methacrylate (TMSPMA) and tetraethoxysilane (TEOS) with cerium addition. Different immersion times (2, 10 and 15 minutes) were used. The characterization of the films were carried out by SEM and the film wettability was determined. The electrochemical behavior of the coatings obtained was evaluated by open circuit potential, potentiodynamic polarization and electrochemical impedance. The results showed the effect of immersion time in the sol on the film uniformity and consequently on the corrosion resistance of the these films.