Tool wear mechanism in diamond tools of single-crystal silicon machining: a molecular dynamics study.

CONTEXT: Single-crystal silicon is a critical material in optical and semiconductor manufacturing; however, its inherent brittleness poses persistent challenges in ultra-precision machining. This study employs classical molecular dynamics (MD) simulations to investigate the atomic-scale wear mechanisms of diamond tools during the nanomachining of single-crystal silicon. The investigation focuses on high-pressure phase transformation (HPPT) of silicon, interfacial chemical interactions consistent with SiC-like local bonding at the tool-workpiece interface, progressive sp3-to-sp2-like structural transitions and amorphization in the diamond tool, and the tribological consequences of rake-face defects-specifically voids and protrusions-on friction, temperature, material removal rate (MRR), machined surface quality, and tool structural integrity. METHODS: Classical MD simulations were performed using LAMMPS software, employing the Tersoff potential for Si-Si and C-C interactions and the Morse potential for Si-C interactions. Three tool conditions were systematically compared: a defect-free (ideal) tool, a void-containing tool, and a protrusion-bearing tool. Key simulation parameters included a cutting speed of 80 m/s, uncut chip thickness of 10 Å, tool edge radius of 20 Å, and rake angle of - 25°. Analyses encompassed stress tensor evaluation, silicon coordination number tracking, radial distribution function (RDF) analysis, temperature evolution, friction force statistics, MRR, atomic surface roughness (Ra), and two-scale fractal dimension characterization of surface defects.