Atomic-scale insights into the material removal mechanism of cerium oxide polished fused silica based on ReaxFF-MD

Abstract

Reactive force field molecular dynamics simulation (ReaxFF-MD) was utilized to investigate the atomic-level material removal mechanism of fused silica polished by cerium oxide (111) abrasives during the computer-controlled optical surface (CCOS) process. The study reveals that interactions between the cerium oxide abrasives and fused silica surface in the presence of water molecules result in the formation of structures such as Ce/Si-OH. During polishing, Ce-O-Si bridge bonds are formed, which transmit mechanical forces to the surface of the fused silica glass, leading to atomic removal through stretching. The CCOS process is characterized by a synergistic interaction of both mechanical and chemical mechanisms. The study also explored the chemical and mechanical effects on the surfaces of cerium oxide abrasives and fused silica under varying pH, pressure, and slip velocity conditions. Experimental validation demonstrated that at pH 11, the surface roughness reached 0.126 nm, and the material removal rate (MRR) peaked at 593.56 nm/min under a high polishing speed of 375 RPM. Additionally, higher polishing pressure (0.2 MPa) further enhanced removal efficiency, with an MRR of 214.63 nm/min. These findings provide valuable insights for optimizing process parameters in practical applications and offer crucial theoretical guidance for achieving picometer-level ultra-smooth surface processing.