Effect of ZnO on the structural, physio-mechanical properties and thermal shock resistance of Li2O-Al2O3-SiO2 glass-ceramics

The composition of lithium aluminosilicate (LAS) with different zinc oxide-magnesium oxide (ZnO-MgO) contents that ranged from 0 to 1.45 wt percent (wt%) was investigated to determine the thermal shock resistance properties of the glass-ceramics. The LAS glasses were melted in an alumina crucible at 1550 degrees C for 5 h, and the green compact samples were then heat-treated at 1100 degrees C for 3.5 h. The presence of zinc oxide (ZnO) in the compositions did not change the major crystal phase of beta-spodumene. However, the addition of ZnO shifted the pronounced peak to a lower angle and increased the percentage of crystallinity from 55% to 59%. Additionally, the function of ZnO in LAS glass-ceramics as the network modifier was confirmed through Fourier Transform Infrared Spectroscopy (FTIR) analysis. The physio-mechanical properties were improved when 1.45 wt% ZnO was added to the LAS glass-ceramics. The results showed increased density (2.42 g/cm(3)), low porosity (0.85%), high flexural strength (125.23 MPa), and low coefficient of thermal expansion (25-800 degrees C) (CTE(25-800 degrees C)) value of 1.73 x 10(-6) degrees C-1. Meanwhile, the thermal shock resistance properties evaluation of the LAS glass-ceramics at different ZnO contents were conducted at different thermal shock temperatures of 200 degrees C, 500 degrees C, and 800 degrees C. The critical temperature of the LAS specimens with 1.45 wt% ZnO demonstrated the ability to withstand a thermal shock at 800 degrees C while preserving 87% of their initial strength of 108.40 MPa, exemplifying the best LAS glass-ceramics properties for rapid high-temperature change applications.