Effect of increasing the Al2O3 content on the phase formation and mechanical properties of lithium disilicate glass-ceramics

Abstract

Lithium disilicate glass ceramics with improved properties were prepared via a thermal treatment method by varying its composition. This study aims to investigate the influence of the concentration of Al2O3 additive oxides on the phase formation and mechanical properties of lithium disilicate glass ceramics prepared by conventional method. The Al2O3 concentration used are 3.0, 4.5, and 6.0 mol% for LCA1, LCA2, and LCA 3, respectively. As the content of Al2O3 increased the glass transition temperature (Tg), the crystallization temperature (Tc), phase formation, and mechanical properties of lithium disilicate glass ceramics varied considerably, demonstrating the substantial effect of Al2O3. After heat treatment at 600 °C and 800 °C for 1 h, the x-ray diffraction results showed that the major phase in all the glass-ceramic samples was Li2Si2O5 and the minor phases were CeO2, LiAlSi3O8, quartz, and Li2SiO3. For the lowest content of Al2O3, the highest flexural strength and Vickers hardness were obtained as 188.34 MPa and 776 HV, respectively. These results were attributed to the interlocking microstructure of rod-like Li2Si2O5 in the LCA1 sample.