High-rate electrochemical dissolution of Ni-Cu alloys in nitrate electrolyte

High-rate anodic dissolution of nickel, copper, and two alloys Ni30Cu7O and Ni65Cu32 in NaNO sub 3 solution was studied, using a flow-channel electrochemical cell. In all experiments, the initial interelectrode distance was 208 mu m and the electrolyte velocity was 15 m s exp -1 . The dependence of the current efficiency and surface brightening on the current density was determined. Voltage transients at various current densities were measured and voltammograms were constructed. Compared to nickel and copper, the alloys showed intermediate behaviour, especially at j > j sub 1 . The shape of the voltage transients and the occurrence of surface brightening were more suitable to detect the existence of a limiting current region than voltammograms, especially for Ni. Using the voltammograms and literature data, anodic and cathodic potentials and the voltage drop in the interelectrode gap at a given current density were estimated for j < j sub 1 .