Atomistic study of nano-cutting bicrystal cubic silicon carbide

Abstract

To solve problems of low machining efficiency and surface/subsurface damage of silicon carbide (SiC), mechanisms of material dislodging and subsurface destruction of bicrystal SiC under nano-cutting were studied by using three-dimensional molecular dynamics (MD) simulation method. Effects of grain boundary (GB) tilt angle and cutting speed on stress, hydrostatic pressure, cutting force, temperature, and subsurface damage depth were analyzed. Results show that GB slope angle has important influence on the spread of strain, hydrostatic stress, and temperature, especially on subsurface damage depth. Specifically, with the increase in GB slope angle, subsurface damage layer decreases, and machined surface morphology improves. The machinability of small GB angle is better than the large GB angle, and the model with grain boundary angle of 4.24° has the best machinability. It is also found that with the increase in cutting velocity, the temperature increases, whereas cutting force and friction coefficient are reduced, which indicates that the increase in cutting velocity can effectively improve surface machined morphology. The research results provide a theoretical reference for future experimental research.