In-Situ Raman Characterization of Initial Corrosion Behavior of Copper in Neutral 3.5% (wt.) NaCl Solution

In order to investigate the role of chloride ion in the corrosion film formation of copper and its evolution over time, the initial corrosion behavior of copper in neutral 3.5% (wt.) NaCl solution was characterized by in-situ Raman spectroscopy along with electrochemical tests. The results demonstrated that the cuprous chloride complexes, such as CuCl and CuCl2- were produced through electrode processes, while the cuprite, Cu2O seemed to be formed via the chemical precipitation reaction instead of a direct electrochemical transformation from the metal matrix or CuCl and it occurred rather slowly. At the open circuit potential, the chlorides were generated first in the initial 2 h and then they transformed to the oxides with the CuCl2-content in the interface increasing. The in-situ Raman haracterization directly evidenced the previously reported mechanism of growth of oxide layers on copper surfaces in neutral Cl- media and clearly showed the formation of a corrosion product film and its evolution over time. The electrochemical tests corresponded to the results of in-situ Raman characterization well.