Effect of plasma treatment of copper on its corrosion behaviour in 3.5 % NaCl solution

The influence of plasma preoxidation treatment on the corrosion behaviour of copper in a 3.5 % NaCl solution was evaluated. The electrochemical techniques used included potentiodynamic polarization curves, electro-chemical impedance spectroscopy and linear polarization resistance at 20, 40 and 60 degrees C. The results showed that the preformed oxides included both cupric (CuO) and cuprous oxides (Cu2O). Potentiodynamic polarization curves showed a reduction in the corrosion current density value by one order of magnitude in the plasma -oxidized specimens. However, for longer exposure times, the corrosion rates were higher for the plasma-oxidized specimens. Corrosion rates increased with an increase in the testing temperature. The corrosion mechanism was changed by the plasma treatment since it was under charge control for the as-received specimens, whereas a diffusion-controlled mechanism was active for the plasma-oxidized specimens at temperatures of at least 20 degrees C.