Semiconducting properties of passive films formed on electroplated Ni and Ni–Co alloys

The semiconducting properties of the passive films on electroplated Ni and Ni–Co alloys were investigated using Mott–Schottky analysis. The cyclic voltammetry (CV) behaviors of Ni indicate that the film thickness will not increase unless the applied potential is higher than 0.504 V (vs. HgO/Hg). The passivity samples treated with CV reveal their behaviors are that of a p-type semiconductor. The three semiconductive parameters, the acceptor density (NA), the flatband potential (Efb) and the thickness of the space charge layer (Lsc) were calculated from the Mott–Schottky plots, respectively. The relationship between the parameters and the protective characters against corrosion was analyzed.