Elastic properties and indentation cracking behavior of Na2O-TiO2-SiO2 glasses

Abstract

The effects of composition on indentation deformation and cracking behavior of Na2O-TiO2-SiO2 glasses were studied in the light of structural considerations and parameters such as the atomic packing density (Cg) and the network energy, using a combination of elastic measurements and micro-hardness indentation experiments. Na2O-TiO2-SiO2 glasses with titania contents of 4–10mol% and sodium oxide contents of 10–25mol% were prepared through a traditional melt-quench process. Indentation experiments were conducted using a Vickers indenter with loads ranging from 10 mN to 49N. Critical loads for crack initiation and cracking patterns were systematically investigated and correlated with the elastic properties of glass. In this ternary system concerning a relatively large range of Poisson's ratio (ν), a minimum in critical crack initiation load was observed at a ν of 0.21–0.22. This study brings to light the unusual role of titanium in the glass network, which gives birth to peculiar trends in the structural and mechanical properties.