X-ray photoemission investigation of the corrosion ®lm formed on a polished Cu±13Sn alloy in aerated NaCl solution

When a polished Cu±13Sn alloy is soaked in a stagnant aerated 0.5 M NaCl solution, a corrosion process occurs. X-ray photoelectron spectroscopy (XPS) shows that the initial surface is covered with a thin SnO2 layer and that after immersion Cu2O and SnO2 are the main components of the corrosion layer. The ratio between these two oxides varies with the immersion time. At the beginning of the immersion, the thickness of the initial SnO2 layer increases due to selective copper dissolution. Then the tin oxide ®lm gets progressively buried beneath a Cu2O ®lm. This study allows us to conclude that as for pure copper, the corrosion process of a polished Cu±13Sn alloy in NaCl solution occurs by diffusion of Cu(I) species through the oxide layer. # 2001 Elsevier Science B.V. All rights reserved