Effect of pH on Corrosion Performance of Cu-Se and Cu-Se-Te Alloys in 3.5% Sodium Chloride Solution

The influence of pH (2, 7, 12) on the corrosion behavior of Cu-Se-Te and Cu-Se alloys in a 3.5% sodium chloride solution was investigated using static immersion testing and electrochemical methods. The morphologies of the alloys after corrosion were observed by scanning electron microscopy. The distribution of elements was detected by energy-dispersive spectrometry, and the phases were identified by x-ray diffraction. The results indicate that the corrosion rate decreases significantly with an increase in pH. No compact protective film forms on the alloy surface when pH is 2; meanwhile, Cu₂(OH)₃Cl and Cu₂O films form on the alloy surface when pH is 7 or 12. The corrosion rates of alloys in the NaCl solution with different pH levels vary because the cathode reaction and the protective films affect the corrosion rate synthetically. In addition, the Cu-0.5Se alloy generally exhibits satisfactory conductivity, strength, and corrosion resistance. The corrosion resistance of the Cu-0.5Se alloy is higher than that of the Cu-Se-Te alloys, particularly at low pH levels.