碳化硅纳米抛光亚表面损伤机理的分子动力学模拟

The lack of study on the damage mechanism of silicon carbide (SiC) during surface micro/nano-machining limits the machined surface quality of SiC and application. Therefore, it is important to understand the damage mechanism of SiC under different polishing parameters for improving the nano-machined surface quality of SiC. The mechanism of subsurface damage of single crystal SiC during nano-polishing is studied by molecular dynamics simulation, and the effects of polishing speed and depth are considered. The result shows that the removal mechanism of SiC gradually changes from adhesion and ploughing mechanisms to cutting mechanisms with the increase of polishing depth. The microcracks are formed at the tip of the slip band through the fracture of the interlayer Si-Si bond on the slip surface. In addition, the greater polishing depth causes the higher efficiency of the workpiece in absorbing kinetic energy, resulting in the more significant impact of polishing speed on the workpiece temperature and mechanical properties. Therefore, better machined surface quality can be got by smaller polishing depth and larger polishing speed. These results provide new insights into the mechanism of deformation and damage for SiC in nano-polishing experiments, and can guide the design of nano-polishing processes to achieve better SiC surface quality.