Influence of Ultraviolet Irradiation on the Corrosion Behavior of ZrO_2-treated Type 304 Stainless Steels in High Temperature Water with the Presence of Hydrogen Peroxide

摘要

Zirconium dioxide (ZrO_2) was selected as a coating material for corrosion inhibition of Type 304 stainless steel (SS) in high temperature water with hydrogen peroxide (H_2O_2). A number of Type 304 SS samples in the shape of a square disk were prepared. They were pre-oxidized in oxygenated pure water at 288°C for 7 days. The samples were then coated with ZrO_2 nanoparticles by hydrothermal deposition at 90°C for 7 days in pure water with ZrO_2 concentrations of 10 ppm and 100 ppm. Electrochemical polarization analyses were conducted to investigate the corrosion behavior of both ZrO_2-treated and untreated samples in 288°C pure water with H_2O_2 concentrations of 50 ppb, 150 ppb, and 300 ppb. Ultraviolet (UV) irradiation was then imposed upon the ZrO_2-treated samples to examine if there was any photoelectric effect on the corrosion behavior of the treated samples. According to the experimental results, the ECPs of the treated samples became slightly higher than those of the untreated ones, but the corrosion rates of the treated samples were actually lower, as expected. The ECPs of all samples (treated or untreated) did not show significant differences when the H_2O_2 concentration was increased from 50 ppb to 300 ppb. However, the corrosion rates did increase with increasing H_2O_2 concentration. Preliminary results showed that UV irradiation on the ZrO_2-treated samples led to decreases in corrosion rates of the samples in H_2O_2-containing pure water, though not to a great extent.