Modified Silane Films for Corrosion Protection of Mild Steel

Chromium pre-treatments of metal have been replaced by silane pre-treatments as more environmental friendly option. Corrosion inhibitors and nanoparticles can be added in the silane sol-gel network have been reported to improve corrosion resistance. The present work investigates the effect of cerium nitrate activated nanoparticles additions into a sol-gel hybrid silane matrix coated on low carbon steel substrates. Two different types of nanoparticles and its mixture (silica, alumina and their equimolar mixtures) at the concentration of 250 ppm were used. Hybrid sol-gel films have been synthesized from mixture of 3-glycidoxy-propyl-trimethoxy-silane (3-GPTMS) and tetraethyl orthosilicate (TEOS). The electrochemical behavior was studied using DC polarization tests after 24 hours of exposure in aerated 0.1 M NaCl. The scanning electron microscopy (SEM) confirmed crack-free surface morpohology for the as-prepared substrates after different pre-treatments. The experimental results have shown that addition of cerium nitrate at 250 ppm and nanoparticles at 250 ppm did not efficiently inhibit the corrosion of low carbon steel, unlike inhibiting properties shown by blank silane film.