Exploring the application of the Kelvin method in studying the history prior to wear and the onset of wear

The onset of wear and the history prior to measurable wear are of importance to fundamental understanding of tribological processes and have attracted increasing interest. In this study, wear of aluminum, copper, and steel at early stages under different loads was investigated using different methods, including the weight loss measurement, morphological observation and in particular the Kelvin probing (KP) technique. It was demonstrated that among the three methods, the KP method was the most sensitive to changes in surface condition and could be used to investigate the history prior to the occurrence of measurable wear that was visible under optical microscope or determined by measuring the weight loss. The KP technique could provide an effective tool to characterize tribological behavior particularly at the early stages of wear.