Evolution of ring structures and method for inhibition in polishing of fused silica

Abstract

Fused silica is widely used in many fields due to its unique properties, which are linked strongly to its nanoscale ring structures. Although an ultra-smooth surface could be achieved by polishing, it still introduces complex changes in the nanoscale ring structures, leading to a degradation of properties. Thus, understanding the polishing-induced evolution of ring structures is of great importance. In this paper, experiments and molecular dynamics simulations were performed to analyze the evolution mechanism, distribution and influencing factors of ring structures during polishing. Finally, an evolution-free surface was obtained. The results demonstrated that the evolution towards small rings occurred at the expense of large rings during polishing. The evolution was driven by the generation and breakage of siloxane bonds due to the coupling action of the load and hydroxylation. A rise of load on a single particle facilitated the evolution and increased the critical evolution depth by generating overcoordinated (OC) atoms. In contrast, the hydroxylation broke rings directly and reduced the load-induced generation of OC atoms, causing the inhibition of the evolution without altering the critical evolution depth. The results provide valuable insights into the evolution of rings and guide the precision machining of fused silica.