THE ANODIC-DISSOLUTION OF 90-PERCENT COPPER-10-PERCENT NICKEL-ALLOY IN HYDROCHLORIC-ACID SOLUTIONS

The anodic dissolution of the 90% copper-10% nickel alloy in hydrochloric acid solutions at the rotating disk was found to be controlled by both mass transfer and reaction in the apparent Tafel region. The kinetics of dissolution are similar to those of pure copper for the partial currents due to the dissolution of both the copper and nickel components from the alloy. A mechanism for the dissolution of the alloy is proposed. This mechanism describes the dissolution as being controlled by the dissolution of the copper from the alloy. In the limiting-current region a film of CuCl precipitates on the surface of the electrode. The reaction in the limiting-current region is controlled by mass transfer. A mechanism which describes the precipitation and dissolution of this film, and which describes the diffusion of the chloride to the surface of the electrode is proposed.