The dissolution of CuNi alloys in hydrochloric acid—I. Rotating disc electrode measurements

The dissolution of pure copper, 90 Cu10 Ni and 60 Cu40 Ni in hydrochloric acid in the concentration range 1/3-3 M was studied using potentiodynamic sweeps and steady-state potential measurements on a rotating disc electrode. Some results are also reported for rotating ring-disc experiments. In the active region copper dissolves as a cuprous species from all three alloys, and in the passive region a film of cuprous chloride formed by a solid state mechanism is probably responsible for passivity. At higher anodic potential cupric species are produced. The alloy behaviour cannot be represented by a simple linear combination of the two partial currents.In the case of the $\text{60}\text{40}$ alloys, behaviour consistent with a partially blocked anode has been observed at higher current densities.