Corrosion protection of 316 L stainless steel by a TiO2 nanoparticle coating prepared by sol-gel method

A uniform and TiO2 nanoparticle coating on steels has been prepared using sol-gel method and hydrothermal post-treatments. The morphology and structure of the coatings were analysed using atomic force microscopy and X-ray diffraction. The anticorrosion performances of the coatings in dark and under ultraviolet illumination have been evaluated by using electrochemical techniques. The influences of coating thickness, pH and NaCl concentration on corrosion protection have been examined as well. The results indicate that the TiO2 nanoparticle coatings on steels exhibit an excellent corrosion resistance due to a ceramic protective barrier on metal surface in dark, and a photo-generated cathodic protection current under UV illumination. The electrochemical impedance spectroscopy measurements provide an explanation to the increased resistance of nano TiO2 particles coated 316 L stainless steel against corrosion.