Impedance and XPS study of benzotriazole films formed on copper, copper-zinc alloys and zinc in chloride solution

The formation of protective layers on copper, zinc and copper-zinc (Cu-10Zn and Cu-40Zn) alloys at open circuit potential in aerated, near neutral 0.5 M NaCl solution containing benzotriazole was studied using electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). Benzotriazole (BTAH), generally known as an inhibitor of copper corrosion, also proved to be an efficient inhibitor for copper-zinc alloys and zinc metal. The Surface layers formed on alloys in BTAH-inhibited solution comprised both polymer and oxide components, namely Cu(I)BTA and Zn(II)BTA polymers and CU2O and ZnO oxides, as proved by the in-depth profiling of the layers formed. A tentative structural model describing the improved corrosion resistance of Cu, Cu-xZn alloys and Zn in BTAH containing chloride solution is proposed. (c) 2008 Elsevier Ltd. All rights reserved.