Effect of Al2O3 additions on the crystallization behaviour and bending strength of a Li2O–ZnO–SiO2 glass-ceramic

In this study, the effect of partial replacement of ZnO by Al2O3 on the crystallization behaviour and bending strength of a Li2O–ZnO–SiO2 glass-ceramic was investigated using differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and mechanical property. The crystallization sequence of the glasses was determined by XRD analysis of the samples subjected to isothermal and nonisothermal heat treatments. All compositions showed volume crystallization with rather fine microstructures. The maximum bending strength was obtained for composition containing 4 wt.% Al2O3, above which a marked decrease was determined. The changes in phase assemblage and microstructures depended on the alumina content and applied heat treatments; these were correlated to the strength of the glass-ceramics.