Understanding the High Scan Rate PDP Curves Obtained By Seccm

Abstract

Scanning electrochemical cell microscopy (SECCM) is progressively employed for investigating corrosion behaviors at localized sites on metal surfaces. Normally, hundreds of potentiodynamic polarization (PDP) measurements are conducted on the sample using a high potential scan rate to reduce the experimental duration. However, polarization curves obtained under such conditions would yield inaccurate Tafel kinetics. In this research, we performed PDP measurements on Al sample at various scan rates using SECCM and obtained reproducible results. The experimental polarization curves were successfully simulated by a high field model that accounted for the cathodic contribution from oxygen reduction reaction and the anodic contribution from Al oxide film growth. By utilizing this model, we were able to extract the true corrosion kinetic properties from the high scan rate polarization curves, which has not been reported previously. This study represents a significant contribution towards enhancing SECCM-based micro-polarization as a robust quantitative technique for corrosion study.