Fundamental understanding of the ductile machinability of fused silica under in-situ laser assisted diamond cutting

Fused silica's ductile machinability was investigated through theoretical molecular dynamics simulation and systematic experiments. Nano-indentation experiments demonstrate that fused silica exhibits a decrease in hardness and an increase in elastic modulus at elevated temperature. Further analysis of the indentations scanned by atomic force microscopy and the density calculated through the established model reveal that high temperature leads to more shear flow and less densification of fused silica. The densification observed during nanoindentation can be attributed to a decrease in the average Si-O-Si angle, as revealed through the investigation of Raman spectroscopy. The decrease in densification, combined with an increase in shear flow at elevated temperature, gives rise to an improvement in the ductile deformability of fused silica. As a result, the surface quality Sa is significantly improved, decreasing from 87.77 nm during conventional diamond cutting to 11.43 nm during in-situ laser assisted diamond cutting and ultimately prolonging the tool life.