Scratching Test of Hard-Brittle Materials Under High Hydrostatic Pressure

This paper proposes machining under high hydrostatic pressure as a new damage-free machining method for hard-brittle materials. Experiments for this study utilized a specially designed scratching test device, and the pin-on-disc scratching tests were conducted with three (3) hard-brittle materials (i.e., silicon, glass, and quartz) under pressure of 400 MPa and zero MPa. Traces of scratches on these specimens were examined with microscopes to evaluate the effects of hydrostatic pressure on machining defects. The results of the experiments show that hydrostatic pressure is efficient in minimizing machining defects and optimizing the productivity of the hard-brittle materials used in these experiments. Based on these findings, the paper concludes that the origin of a machining crack must exist in the subsurface of the workmaterial.