Nanoscale removal mechanisms in abrasive machining of brittle solids

Brittle solids with dominant covalent-ionic bonding, including single crystals, polycrystals, and optical glass, are core materials for modern microelectronic and optoelectronic devices that are widely used in energy, communication, transportation, and medicine sectors. In high performance device applications, those brittle materials must be machined into parts that often have an extremely smooth surface and a damage-free subsurface with sub-micron precision. Optimisation of an abrasive machining process for the brittle solids can significantly enhance production efficiency and reduce manufacturing cost, as well as prolong device life. The development of high efficiency and low damage ultraprecision shaping technologies for this class of solids requires an in-depth understanding of their deformation and removal mechanisms at nanoscale. In this work, the fundamental mechanisms of deformation and removal of brittle materials involved in individual or cumulative contacts with blunt and sharp grits are analysed, using the scratch-related micromechanics as the theoretical basis. Essentials of brittle-to-ductile transitions in abrasive machining are outlined. Influence of the diversity in material microstructures in determining local deformation and subsequent removal is highlighted. Practical requirements are suggested for further advancing ultraprecision abrasive machining of those brittle solids.