A study on synergistic effect of chloride and sulfate ions on copper corrosion by using electrochemical noise in asymmetric cells.

The current study includes a systematic examination of copper corrosion initially in each of NaCl and Na2 SO4 solutions separately and then in the mixture solution of Cl- and SO4 2- ions as aggressive ions. Electrochemical current noise (ECN) signals resulting from asymmetric (Asy) as well as symmetric (Sym) cells have been interpreted using wavelet transform (WT) along with statistical procedures. The signals have been detrended and the decomposition of every signal has been carried out into 8 crystals. Then the standard deviation of every crystal has been illustrated with the standard deviation of partial signal (SDPS) plots. The Asy electrodes increased the pitting detection on copper compared with the Sym ones, indicating higher efficiency of the Asy electrodes. Asymmetric-copper electrodes have been studied using SDPS plots at different temperatures (40, 60, as well as 80 °C). Finally, in order to partly understand the effect of Cl- and SO4 2- ions on the corrosion of copper, the stabilization of Cu2+ cations by Cl- and SO4 2- ions in aqueous solutions have been modeled by DFT calculations. The derived results are in accordance with the experimental data.