Effects of mechanical interactions on friction-induced subsurface densification of borosilicate glass

Abstract During the wear process of glass materials, not only surface mechanochemical wear, the friction-induced subsurface densification of glass can also occur. In this study, the effect of mechanical interactions, such as contact pressure, sliding speed, and sliding time on subsurface densification of borosilicate glass was studied by rubbing with stainless steel ball in DI water. The subsurface densification of glass upon mechanochemical wear is validated by the volume recovery of mechanochemical wear track upon sub-glass transition temperature (sub-Tg) annealing treatment as well as the increased nanomechanical properties inside the mechanochemical wear track. In addition, it is found that the contact pressure shows the strongest effect on subsurface densification of borosilicate glass, compared to the sliding speed and sliding time. Further analyses indicate that the highest contribution of contact pressure is accompanied with higher influence of dissipated energy during friction process, facilitating the transfer of mechanical energy into subsurface region, resulting in more subsurface deformation of the glass network. The obtained results can provide deeper insights into surface wear and subsurface densification of silicate glass materials during manufacturing and serving process.