Strength and Microstructure in Lithium Disilicate Glass‐Ceramics

Abstract

The effect of heat treatment on the microstructure of Li,OAl2O3-SiO2 glass-ceramics which contain crystals of either Li2Si03, Li2Si,05, or both was investigated quantitatively. Strength determinations for abraded rods were correlated with heat treatment on the basis of both size and distribution of crystals and the type and amount of crystal phases present. The presence of Li2Si205 crystals enhanced the strength, whereas the presence of Li2Si03 crystals did not change the strength of the abraded parent glass. The interrelation between strength and microstructure is discussed.

Microstructural evolution and physical behavior of a lithium disilicate glass–ceramic

“…The one-stage heating schedule only involved a single heating rate and holding time. The two-stage heating schedule typically entailed first and second heat treatments for nucleation then crystallization respectively [29,33]. The initial heat-treatment stage was important to establish a kinetically favorable setting for stabilizing lithium metasilicates [33].…”

“…The two-stage heating schedule typically entailed first and second heat treatments for nucleation then crystallization respectively [29,33]. The initial heat-treatment stage was important to establish a kinetically favorable setting for stabilizing lithium metasilicates [33]. The second heat-treatment stage, usually at a higher temperature range than the initial, supplied the thermal energy to induce growth of lithium disilicates and to thermodynamically destabilize the lithium metasilicates [33].…”

“…The initial heat-treatment stage was important to establish a kinetically favorable setting for stabilizing lithium metasilicates [33]. The second heat-treatment stage, usually at a higher temperature range than the initial, supplied the thermal energy to induce growth of lithium disilicates and to thermodynamically destabilize the lithium metasilicates [33]. According to Borom et al (1975), the growth of lithium disilicate crystals was not dependent on the crystalline nuclei of lithium metasilicates [33].…”

“…The second heat-treatment stage, usually at a higher temperature range than the initial, supplied the thermal energy to induce growth of lithium disilicates and to thermodynamically destabilize the lithium metasilicates [33]. According to Borom et al (1975), the growth of lithium disilicate crystals was not dependent on the crystalline nuclei of lithium metasilicates [33]. Rather, lithium metasilicates kinetically competed with lithium disilicates but slowly diminished since it was thermodynamically less stable than lithium disilicates at high temperatures [33].…”

“…According to Borom et al (1975), the growth of lithium disilicate crystals was not dependent on the crystalline nuclei of lithium metasilicates [33]. Rather, lithium metasilicates kinetically competed with lithium disilicates but slowly diminished since it was thermodynamically less stable than lithium disilicates at high temperatures [33]. In contrast, Zheng et al (2008) suggested an interdependence between lithium metasilicates and lithium disilicates, where lithium disilicates could be epitaxially grown on lithium metasilicates [29].…”