The effects of abrasive moving speed and motion mode on the thinning mechanism of SiC in three-body contact

Three-body contact is the main contact type in polishing process and leads to a different thinning mechanism than the two-body contact. Molecular dynamics simulation is employed to investigate the thinning mechanism of 3C-SiC substrate in three-body contact. The thinning mechanisms of 3C-SiC under different moving speeds and motion modes of diamond abrasive are compared. Through the analysis of force, temperature, potential energy, stress distribution and atomic flow field, the causes of different thinning mechanisms are explained. It is found that the influence of moving speed is mainly reflected in the temperature rise of substrate when the motion mode of abrasives is the same. The changes of motion mode will significantly alter the stress distribution, which is closely related to the damage depth and atomic flow field. When the feed speed is the same, increasing the self-rotation speed of abrasives can reduce concentration zone of hydrostatic stress and then reduce the damage depth. The self-rotation of abrasives will also change the distribution of von Mises stress, resulting in the different displacement directions of 3C-SiC atoms. Dislocations are more easily generated when the displacement direction of SiC atoms is the same. The moving speed of abrasive is found to have little effect on the thinning mechanism, while the motion mode of abrasive will significantly change the thinning mechanism.