Characterization of SiO2-TiO2 Coatings on 316l Stainless Steel Substrates

This paper reports nano-structured sio2-tio2 coatings using the sol-gel technique on 316l steel substrates. nanoindentation, surface analysis and corrosion resistance tests were performed on different samples. the nanomechanical tests allowed to compare the uncoated steel samples (eavg = 193.24gpa and the mean hardness of 2.63gpa and coated steel samples (eavg = 287.38gpa and mean hardness of 5.74gpa), resulting in an improvement of the resistance and modulus of elasticity of the coated steel substrates. from a surface analysis an average thickness of 1.12μm was obtained in the coated samples, presenting a dense and consolidated coating. polarization resistance (pr) and electrochemical impedance spectroscopy (eis) tests were performed. the pr tests showed a resistance of 2.11 × 10^5 (ω cm^2) for the uncoated steel, while the coated steel showed a resistance of 3.46 × 10^5 (ω cm^2), indicating an increase in resistance compared to the bare steel. the eis tests showed greater resistance by the coated steel (5.8× 10^5 (ω cm^2)) compared with the bare steel (2.8× 10^5 (ω cm^2)). the effects of the electrolyte in both conditions were observed by sem after immersion for 24 h, showing pitting by the bare steel and good protection by the coated steel.