Effect of heat treatment temperature on the performance of nano-TiO2 coating in protecting 316L stainless steel against corrosion under UV illumination and dark conditions

In this study, the influence of heat treatment temperature on the corrosion protection performance of nano-TiO2 coated on 316L stainless steel has been investigated in ultraviolet (UV) illumination and dark conditions. Uniform crack-free nano-TiO2 coatings were prepared on 316L stainless steel using a sol–gel process. Surface morphology, thermal behavior, crystallographic structure and molecular bonds of the TiO2 coatings were analyzed by using SEM, AFM, STA, XRD, and FTIR, respectively. Photodegradation performances of the TiO2 coatings were investigated based on the degradation of an aqueous solution of methyl orange as a model. Furthermore, the influence of heat treatment temperature of the coatings on their protective properties was evaluated in both dark and UV illumination conditions based on the obtained polarization curves. The results demonstrated that the optimum corrosion protection performances of the coatings are achieved at heat treatment temperatures of 500 °C and 450 °C for dark and illumination conditions, respectively, while the sample heat treated at 450 °C showed the best photocatalytic activity.