ANODIC AND CHEMICAL DISSOLUTION PRODUCTS OF COPPER IN AMMONIACAL SOLUTIONS NATURE OF THE PASSIVATING DEPOSITS

It was seen with different electrochemical methods and by radiography that the compounds CuCl, Cu2O, and CuCl2.3Cu(OH)2 are copper dissoluti on products in solutions containing CuCl2, NH4Cl, and NH3. Anodic diss olution was found to occur in steps; the mechanism of formation of the anodic passivating films was established. The influence of process pa rameters on individual steps of the process was determined. It was sho wn that only the loose part of the deposits is eliminated by fast rota tion; the compact passive layer remains on the electrode. Dissolution occurs through the passive film whatever the conditions.