An atomistic removal model based on transition state theory to predict the chemical wear of monocrystalline diamond

Abstract

The chemical wear of monocrystalline diamond by metal has been verified as a thermally activated process by wear experiments and sliding tests. However, there still lack convincing explanations on the diverse wear-diamond ability of different metal species. An atomistic wear model based on the concepts of transition state theory has been built to depict the chemical wear mechanism of diamond. The model defines the unit reaction of the wear process, making it possible to calculate the removal rate of single carbon atom using energy barrier value. The barrier mainly depends on metal specie and interfacial distance, and lower barrier generates higher reaction rate. Besides, for each metal-diamond pair, there exists a minimum energy barrier corresponding to a critical interfacial distance, under which an optimal wear rate of diamond can be obtained. This has been extended to the macroscopic wear process by a contact model. Finally, predictions based on ab-initio calculations are compared with experimental wear results in references, and consistency in the trend of wear-diamond ability for Al, Cu and Fe has been achieved.