The Role Of UV Illumination On The Atmospheric Corrosion Of Q235 Carbon Steel And 09CuPCrNi Weathering Steel

The preliminary studies of the role of UV illumination on the atmospheric corrosion of Q235 carbon steel and 09 CuPCrNi weathering steel in the presence of NaCl particles have been studied, UV illumination could obviously accelerate the corrosion rate of the above two kinds of metal and promote the generation of the corrosion products β-FeOOH, α-FeOOH and Fe3O4. Under the UV illumination, the rusted specimens can obtain a positive voltage in the bulk NaCl solution, the results showed that the corrosion products with the characteristics of semiconductor coluld generate photovoltaic effect, which plays a significant role in promoting corrosion of the metal. The role of the corrosion products with the semiconductor properties in base metal corrosion was further studied. Stripping the corrosion products from the base metal, and then thin-film photo-electrodes were fabricated with the corrosion products. The direction and the quantities of the current density between the corrosion products and the base metal were tested in the light illumination, so the detailed influence mechanism of the corrosion products with semiconductor properties effecting the metal corrosion could be proposed.Based on the above, three kinds of common marine environment corrosion products γ-FeOOH, β-FeOOH and γ-Fe2O3 were laboratory synthetic. γ-FeOOH, β-FeOOH, γ-Fe2O3, mixed γ-FeOOH/β-FeOOH and mixed γ-FeOOH/γ-Fe2O3 film electrodes were fabricated, and respectively coupled with Q235 carbon steel and 09 CuPCrNi weathering steel. Under the condition of visible light, the photo-induced voltage and photo-induced current density values of the coupled system were tested. A positive voltage change and a negative photocurrent density value were obtained fron the experiments, the positive photo-induced voltage result showed that photo-induced electrons generated by the corrosion products with the semiconductor properties under visible light irradiation were not transferred to the coupled metal, however the photo-induced holes could capture electrons from the coupled metal electrodes, thus promoting the dissolution of the metal anode and further improve the corrosion of the metals. The photoinduced current density value of the system of the mixed thin film photoelectode coupled with the base metal was much higher than the system of the single thin film photoelectode coupled with the base metals, and the main reason is the existence of the heterojunction electric field in the mixted thin film photoelectrodes.