Wear mechanism in nano polishing of SiCp/Al composite materials using molecular dynamics

SiC particle-reinforced Al metal matrix composites (SiCp/Al) are typical difficult-to-machine materials due to the heterogeneous constituent. In order to explore the material removal mechanism in fixed abrasive polishing (FAP), polishing experiments were performed on SiCp/Al at 15 rpm and 35 rpm respectively, and surface integrity, including surface damage and material removal forms, was evaluated to explore the effects of different polishing speeds on it. The results indicate that high-speed polishing at 35 rpm may result in better surface quality. The polished SiC surface changes from a concave cavity to a fish scale shape, and the removal form of SiC particles changes from whole extraction and brittle fracture to ductile removal. A removal model for SiCp/Al in consolidated abrasive polishing was established, and the material removal mechanism was revealed. Simulate the removal of SiC particles at different depths using molecular dynamics simulation. We find dislocations will generate not only at the polishing region but also at the SiC-Al interface. Moreover, the motion of dislocations is obstructed by the nanoparticles, resulting in accumulation of dislocations between the tool and particles. Furthermore, it was found that the removed silicon carbide particles exhibited three-body wear during low-speed polishing, while they turned into two-body wear during high-speed polishing. Material removal rate (MRR) data showed that the standard deviation was reduced by 80% when switching from low-speed to high-speed polishing. This significant decrease underscores that high-speed polishing helps to improve SiCp/Al surface quality. Our researches benefit to understand the mechanical removal mechanism of SiCp/Al substrates and give theoretical guide for improving the machining technology of FAP.