Indentation-Induced Densification of Sodium Borate Glasses

Abstract

Glass is densified under a high compressive stress. Densification of glass also occurs under a sharp diamond indenter. Although indentation-induced densification of some silicate glasses has been reported, there is less information on the densification of other types of glasses. In this study, indentation-induced densification of binary sodium borate glasses was investigated. The volume change in Vickers indent by annealing attributes to the relaxation of densified volume under the indenter. For all binary sodium borate glasses, large shrinkage of Vickers indentation was observed after annealing, and the densification of sodium borate glasses was evidenced. The volume change in Vickers indent on sodium borate glass is more than 70 %. The ratio of densified volume to total indentation volume depends a little on the glass composition.