Effect of CaO/Y2O3 on the crystallization and properties of Li2O-Al2O3-SiO2 glass-ceramics

Glass-ceramics with excellent mechanical properties often come at the expense of reduced transmittance. In this sthdy, we prepare Li₂O-Al₂O₃-SiO₂ (LAS) system glass-ceramics that exhibit high transmittance, outstanding mechanical properties and relatively low coefficient of thermal expansion. Utilizing techniques such as differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and microhardness testing, we investigate the effects of CaO/Y₂O₃ on the crystallization, microstructure, transparency and mechanical properties of LAS glass and microcrystalline glass. The results indicate that heat treatment at 610 °C for 2 h followed by 800 °C for 2 h yields β-quartz solid solution (Li₂Al₂Si₃O₁₀) as the main crystal phase. As the CaO/Y₂O₃ ratio decreases, the grain size and thermal expansion coefficient of the glass-ceramics decrease, while the flexural strength and microhardness initially increase before subsequently declining. At a CaO/Y₂O₃ ratio of 1, the glass-ceramics demonstrate optimal performance, achieving a transmittance of up to 80 %, a microhardness of 8.74 GPa, a flexural strength of 319.44 MPa, and a coefficient of thermal expansion of 2.91 × 10⁻⁶/°C.