The abrasive wear of alumina: correlation with electron triboemission

This study reports the measurements of wear volume and the cumulative triboemission of electrons that are a consequence of multi-pass abrasion of alumina by a diamond indenter in vacuum. The interpretation of these measurements is facilitated by an analysis of the wear scar surface morphology. Wear volume measurements and the examination of the wear scar surface by SEM are necessarily post hoc and, therefore, provide limited insight into the time dependence of wear processes. In this study, the feasibility of using triboemission as a real-time probe (on the order of seconds) of the abrasive wear of ceramics is discussed. A severe-to-mild wear transition is observed after approximately 20 passes with 10 N load. No wear transitions are observed with 30 N load up to 18 passes. A transition in the fraction of plastic debris coated on the wear scar appears to occur concurrently with the wear transition at 10 N load. The wear volume and the fraction of plastic debris film are measured at discrete pass numbers (the ends of the abrasion period) and, therefore, the temporal evolution of the wear process transition is not known. The triboemission, on the other hand, is measured quasi-continuously (separation between measurements is 1 s) and displays an abrupt change in the slope of the cumulative triboemission with respect to the number of passes, at a pass number that is consonant with the transitions in wear rate and fraction of plastic debris film. Evidence is provided that in fact the transitions in wear rate, plastic debris fraction, and cumulative triboemission slope are concurrent. An interpretation of these results is discussed.