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

Abstract

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 °C for 5 h, and the green compact samples were then heat-treated at 1100 °C for 3.5 h. The presence of zinc oxide (ZnO) in the compositions did not change the major crystal phase of β-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/cm3), low porosity (0.85%), high flexural strength (125.23 MPa), and low coefficient of thermal expansion (25–800 °C) (CTE(25–800 °C)) value of 1.73 × 10−6 °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 °C, 500 °C, and 800 °C. The critical temperature of the LAS specimens with 1.45 wt% ZnO demonstrated the ability to withstand a thermal shock at 800 °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.