Investigation on nano-grinding process of GaN using molecular dynamics simulation: Nano-grinding parameters effect

Nano-grinding is an essential step in ultra-precision machining for brittle material semiconductor workpieces in order to improve the surface quality and preserve strength prior to practical application. This study utilizes molecular dynamics (MD) method to conduct single-crystal gallium nitride (GaN) nano-grinding simulations under varying parameters. The damage mechanism of the surface/subsurface on the nanometer scale is explored through atomic displacement analysis, radial distribution function (RDF), phase transition, dislocation analysis, processing force, temperature distribution, and residual stress distribution. The machined surface quality and crystal structure distribution in the subsurface damage layer (SDL) are also examined, and a strong correlation is found between the parameters in nano-grinding. The nano-grinding speed is closely associated with the post-processing surface morphology, crystal phase transition, and temperature distribution in the GaN workpiece. Additionally, the ambient temperature has a considerable effect on the surface morphology and crystal phase transition. Moreover, the nano-grinding depth has a considerable influence on the surface morphology, phase transition, dislocation, processing force, and the temperature-dependent distribution of the residual stress in the GaN workpiece. This work reveals the relationship between the parameters and the mechanical properties of the machined surface in nano-grinding, and elucidates the damage mechanism of the subsurface, thus providing a helpful guide to the optimization of ultra-precision machining.