The capacitances of passivated electrodes were investigated to aid in explaining the effect of capacitive discharging during scribing of rotating cylindrical electrodes. In scribing experiments, a capacitive current is associated with the transient current response which results from removing the passive film. The effective capacitance of the electrodes were acquired by using triangular sweep voltammetry (TSV), galvanostatic double pulse technique (GDP), and electrochemical impedance spectroscopy (EIS) conducted on Fe -16 wt%Ni -16 wt%Cr and Fe -25 wt%Ni -25 wt%Cr alloys immersed in 0.1 M H2SO4 -0.01 M
KCI. The TSV technique involved the electrical perturbation of an electrode/solution interface with a triangular wave potential while in the passive condition (i.e., +350 mV SCE). The TSV and GDP experiments determined that the effective capacitance of the electrode/solution interface ranged from 0.1 mF/cm2 to 0.735 mF/cm2 depending on the technique...
Keywords: scratched electrode, ohmic potential, capacitance, impedance spectroscopy, transient current