Some experiments on the scratching of silicon:: In situ scratching inside an SEM and scratching under high external hydrostatic pressures

To elucidate the mechanisms of material removal in ultra precision machining of silicon involving deformation and fracture, in situ scratching of silicon with a diamond stylus inside a scanning electron microscope (SEM) using a specially designed tribometer and scratching under zero and high (400 MPa) external hydrostatic pressures using a specially designed high-pressure machining apparatus were conducted. The resulting scratches were examined in an SEM to evaluate the influence of depth of cut and hydrostatic pressure on the nature of scratches produced (smooth versus fractured surfaces) and the possible brittle–ductile transition. Experimental results indicate that hydrostatic pressure plays an important role in minimizing fracture and producing smooth surfaces. Reasonable agreement of the experimental results with the meso-plasticity FEM simulation of indentation was obtained.