Abstract
Titanium dioxide (TiO2) coupled with ultraviolet irradiation was selected as a coating material for corrosion mitigation of Type 304 stainless steel (SS) in high temperature water with different water chemistry conditions. Type 304 SS specimens were pre-oxidized in oxygenated pure water at 288°C for 14 days, or they were pre-oxidized in oxygenated pure water at 288°C for 7 days and then further exposed to hydrogenated pure water also at 288°C for another 7 days. The pre-oxidized specimens were deposited with TiO2 nanoparticles by hydrothermal deposition at 150°C or 280°C for 4 days in pure water with a TiO2 concentration of 10 ppm or 100 ppm. Electrochemical potentiodynamic polarization analyses were conducted to investigate the corrosion behavior of both TiO2-treated and pre-oxidized specimens in 288°C pure water with H2O2 concentration of 300 ppb or H2 concentration of 50 ppb. Ultraviolet (UV) irradiation was then imposed upon the TiO2-treated specimens to examine if there was any photoelectric effect on the corrosion behavior of the treated samples. The TiO2 loading on the specimen treated at 280°C was significantly greater than that treated at 150°C, as verified by the ICP-MS loading measurements. The results showed that UV irradiation on the TiO2 treated samples led to decreases in corrosion rate of the samples in high temperature water with the presence of hydrogen peroxide. Further examinations on the impact of UV irradiation on the corrosion behavior of TiO2 treated Type 304 SS samples in H2O2-rich or hydrogenated pure water are being conducted.