Indentation-induced densification of soda-lime silicate glass

Abstract

Abstract Glass is densified under a sharp diamond indenter. The densification is not a volume conservative process, and does not contribute to the volume strain around the indentation. This means that densification affects residual stresses around the indentation impression. In order to estimate the densification volume, three-dimensional images of Vickers indentations on soda-lime silicate glasses were obtained before and after annealing. Only the densified volume can be recovered by annealing. After annealing at around glass transition temperature, large volume recovery (55 – 80 %) of Vickers indentation was observed for soda-lime silicate glass. The volume recovery is much larger than the recoveries of indentation diagonal and depth. It is found that the densification of glass under the sharp indenter cannot be ignored for evaluating crack initiation and brittleness of glass. In addition, the residual stresses around the indentation impression were also estimated from the plastically deformed volume and the size of plastic zone around the indentation.