Stainless steel has been used in a wide variety of industries due to its mechanical, anticorrosion and biocompatibility properties. However, its passive layer can be compromised under aggressive environments leading to corrosion. There are several chemical conversion treatments that are applied on the steel’s surface to improve its corrosion resistance. The most commonly used conversion coatings are based on hexavalent chromium, a compound that is carcinogenic and very hazardous pollutant. The new researches are looking for alternatives that achieve the same or better corrosion inhibition. As an alternative less toxic method, this work presents the use of the sol-gel as a chemical conversion treatment to obtain TiO₂ thin films on a stainless steel 316L..

The sol-gel was prepared with titanium butoxide as a precursor; adding niobium and vanadium salts as corrosion inhibitors. Once prepared, the sol-gel was aged for 24 hours. The substrate (stainless steel 316L) was cut in 5x2cm pieces to be ground and polished. Each piece was rinsed with water and finally with acetone. The method dip-coating was used to apply the sol-gel on the surface of the substrate. The dipping was done at three different speeds using a device previously designed and built in the laboratory. After the sol-gel is applied, the pieces are heat treated at different temperatures: 300°C, 500°C and 700°C. The films were characterized by X- Ray Fluorescence and Raman Spectroscopy. These techniques showed the presence of TiO₂, with different structures depending on the thermal treatment temperature: amorphous, anatase and rutile. The corrosion behavior was studied in a 3% NaCl solution by Potentiodynamic Polarization Curves and Electrochemical Impedance Spectroscopy. The effect of the dipping speed and the actual TiO₂ structures on the anticorrosive properties were reported.