STUDY OF THE ANODIC CURRENT-VOLTAGE CURVE OF AN IRON-NICKEL ALLOY IN NORMAL SULFURIC-ACID

The anodic steady-state polarization curve of an Fe-31% Ni rotating disk electrode in normal sulfuric acid was studied. As in the case of iron in similar conditions, a Z-shaped curve was found and, in a part of the curve, called the transition region, several electrochemical processes (homogeneous dissolution, intergranular dissolution, passivation) coexist on different areas of the electrode surface. The experimental study of the current density distributions and dissolution morphologies on the electrode surface, in the different regions of the curve, allowed us to test the validity of a theoretical model developed to explain the curves of iron electrodes. In this way, we could point out significant differences between the processes occurring at iron and iron-nickel electrodes, and we obtained the current density-potential relationship describing the kinetic laws of the processes.