Study on the removal mechanism of defective sapphire materials by molecular dynamics

Abstract Polished sapphire is widely used due to its excellent physical properties. However, the polishing mechanism of sapphire remains unclear, particularly the influence of subsurface defects on polishing quality, which requires further investigation. This study employs molecular dynamics simulation to investigate the polishing process of sapphire materials containing subsurface defects, analyzing the effects of subsurface defects, polishing depth, speed, and abrasive particle size on the material removal. The results indicate that the presence of subsurface defects reduces polishing force, decreases the generation of dislocation lines, and increases the friction coefficient and thickness of the subsurface damage layer. The increase of polishing depth will enhance the material removal rate, facilitate the removal of deep subsurface defects, but simultaneously increase the thickness of the subsurface damage layer. When polishing speed increases, polishing force changes minimally, while the material removal rate significantly improves, and the thickness of the subsurface damage layer also increases. When the abrasive particle size increases, the material removal rate significantly improves; however, the surface quality deteriorates after polishing. The study found that setting the polishing speed to 200 m s −1 , polishing depth to 10 Å, and abrasive particle radius to 25 Å can effectively remove subsurface defects while achieving a high material removal rate and subsurface quality.