Atomic understanding of the evolutionary mechanism of fused glass densification generation during single particle scratching

The densification of fused glass during processing has a significant impact on the performance and application of fused glass components. However, the precise atomic mechanisms underlying densification remain elusive. In this study, we explore the atomic mechanisms responsible for densification in fused glass during single particle scratching, with a focus on the scratching depths and environmental humidity. We employ reactive force field molecular dynamics (ReaxFF MD) simulations for our investigation. We subjected models to scratching under various humidity conditions using a spherical virtual indenter with a 20 Å radius. The scratching depths were set at 10 Å and 15 Å, respectively, with a constant scraping speed of 40 m/s. Our findings indicate that water molecules impede lateral atom movement on the fused glass surface while enhancing vertical flow. Furthermore, water molecules facilitate the volume recovery of fused glass following scratching. The transfer of hydrogen (H) atoms within the fused glass, facilitated by Si–O–H⋯O–Si structures, plays a crucial role in promoting volume recovery. The ultimate density distribution of fused glass results from a combination of atomic displacement during scratching and subsequent volume recovery. This study enhances our atomic-level understanding of densification generation in fused glass.