Load dependence of densification in glass during Vickers indentation test

The load dependence of densification during a Vickers indentation test was investigated for three commercial glass compositions, soda-lime silicate glass, aluminoborosilicate glass, and lead borosilicate glass, each of which exhibits markedly different susceptibility to crack initiation. The contribution of densification to the total deformation due to indentation was evaluated as the ratio of the depths of indentation before and after heat treatment measured with an atomic force microscope (AFM). For the soda-lime silicate and aluminoborosilicate glasses, the contribution of densification decreases with increasing applied load, but the rate of the decrease is less for the alumonoborosilicate glass than for the soda-lime silicate glass. For the lead borosilicate glass, the contribution of densification is low throughout the range of loads investigated. The residual stress can be estimated from the contribution of densification, and the variation of load dependence of the residual stress is considered to result in a large difference in the crack initiation load among the glasses. (C)2011 The Ceramic Society of Japan. All rights reserved