VERIFICATION OF THE VALIDITY OF PEAK BARE SURFACE CURRENT DENSITIES OBTAINED FROM THE SCRATCHED ELECTRODE

Current densities measured from a small scratch generated in a relatively large rotating disk electrode have been measured and quantified in relation to the relative areas of the scratch and the surrounding passive surface. The data show that the peak bare surface current density measured using the scratched rotating disk electrode does not depend on the ratio of the area of the passive filmed surface to that of the scratch surface. Peak bare surface current densities measured from fracture surfaces of large specimens of circular cross section are subject to a far larger ohmic potential drop than that experienced by a small scratch. The data explain the recent observations of Wei, Gao, and Xu(1).