ROTATING-RING-DISK ELECTRODE STUDIES OF CU-ZN ALLOY ELECTRODISSOLUTION IN 1M HCL - EFFECT OF BENZOTRIAZOLE

The electrodissolution behavior of Cu and Cu-rich Cu-Zn alloys in 1M HCl containing benzotriazole (BTA) was studied using rotating ring-disk electrodes. Cu(I) was the main product of Cu-Zn alloy dissolution with Cu(II) detected only at higher potentials. EIectrodissolution of the Cu component was similar to that of copper with an apparent Tafel slope of 60 mV/dec. Cu component dissolution rates exhibited strong mass-transfer effects in the entire potential range studied. A CuCl film formed on the alloy surfaces in the current peak region. In the limiting current region the rates of Cu(I) dissolution from both alloys and copper were esentially equivalent and indicate CuCl2- as the principal diffusing species. Significant selective electrodissolution of Zn was observed in the apparent Tafel region. The formation of a duplex film was indicated in the presence of BTA with a nonporous Cu(I) BTA inner layer and a porous CuCl outer layer.