The role of UV illumination on the initial atmospheric corrosion of 09CuPCrNi weathering steel in the presence of NaCl particles

• UV strongly affects the NaCl-induced atmospheric corrosion of 09CuPCrNi WS.
• Positive photo-voltages were obtained on rusted 09CuPCrNi WS.
• UV significantly increases the charge carrier density of the corrosion products.
• UV affects the processes of the corrosion product formation during exposure.
• UV influences the atmospheric corrosion reactions due to the photovoltaic effect.

Effect of UV illumination on the NaCl-induced atmospheric corrosion of 09CuPCrNi weathering steel (WS) was qualitatively and quantitatively studied in this work. UV illumination strongly affects the NaCl-induced atmospheric corrosion process of 09CuPCrNi WS mainly through the photovoltaic effect of the corrosion products with semiconductor properties. The photogenerated electrons and holes can directly participate in the cathodic and anodic reactions and thus directly affect the atmospheric corrosion rate of 09CuPCrNi WS. Meanwhile, the photogenerated electrons and holes can directly involve in the corrosion product formation process and therefore affect the performance of the corrosion product layer formed under UV illumination.