Evolution of Nano-notches on the Surface of SiC with Different Crystal Forms during Cutting in the Water Environment

Different crystal forms of SiC exhibit different machining characteristics, and the evolution of notches on the surface of SiC has a significant impact on the machining process. In order to investigate the effect of notch evolution on SiC machining in a more realistic environment, the nano-cutting processes of 3C-SiC, 4H-SiC, and 6H-SiC in the water environment are investigated by molecular dynamics (MD) simulation. It is found that the shape of damaged area in 3C-SiC is significantly different from that in 4H-SiC and 6H-SiC because of the different slip planes. Besides, the evolution of notches is also related to the slip planes. For 4H-SiC and 6H-SiC, the basal slip can easily start from the tip of the notch, which will lead to differences in material removal methods. The basal slip in 4H- and 6H-SiC can reduce the average tangential force and damage depth. In addition, the concentration of Von Mises stress in different crystal forms of SiC exhibits significant anisotropy. However, the stress concentration can effectively alleviate by the notches because they can provide additional deformation space for SiC. Those findings reveal the evolution mechanism of notches and can provide some theoretical guidance for the control of machining damage in SiC.