Investigation on the mechanism of wear of single crystal diamond tool in nanometric cutting of iron using molecular dynamics (MD) and the development of generalized potential energy surfaces (GPES) base on ab initio calculations

Abstract

Scope and Method of Study: Diamond, the hardest of all materials known, undergoes severe wear in the machining of iron. This is because of the strong chemical affinity of iron towards carbon. However, the micro-mechanisms of wear are not well understood. A review of literature indicates graphitization of diamond as the leading cause of wear. Lack of direct evidence led us to investigate the wear mechanism of diamond in the machining of pure iron by MD simulations.

Findings and Conclusions: In this investigation, the role of iron in the wear of diamond was established. MD simulations of nanometric cutting were conducted at 100 m s^-1. It has been shown that diamond initially graphitizes and subsequently reacts with iron to form iron carbide, thus confirming the plausible mechanism proposed some 30 years ago.

Central to atomistic simulations is the potential energy surfaces (PES). In this investigation, we have advanced two methods for the development of PES. The first involves modification of the parameters in the existing analytical functional forms, such as Tersoff potential, and the second method involves the development of generalized PES independent of any specific functional form using ab initio calculations, many body expansion, and neural networks. These methods were developed so that PES for different materials can be obtained.