Effect of mechanical properties on sintered lithium aluminosilicate glass ceramic and its thermal shock resistance properties

Abstract

Lithium aluminosilicates (LAS) glass-ceramic is well known for its excellent low thermal expansion coefficient (CTE). Low CTE signifies the better of thermal shock resistance properties of LAS glass ceramic and that properties can be inferred by flexural strength via three-point bending test. Beforehand, in order to study the effect of soaking time on mechanical properties of LAS glass-ceramic, LAS glass ceramic was prepared by the melt-quenching method and sintered at 950°C for various soaking time (30 minutes, 1 hour and 2 hours). The effect of soaking time on LAS glass ceramics properties was investigated via X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), density and hardness test. The results showed that LAS glass-ceramic sintered at 1 hour exhibits highest Vickers hardness, density and low porosity value of 929 MPa, 2.427 g/cm3 and 39.4%, respectively. XRD analysis was also conducted to identify phase changes upon the prolong soaking time and the microstructure of LAS glass-ceramic was observed as well via FE-SEM. The complete transition of crystalline phases from β-eucryptite (LiAlSiO4) to β-spodumene (LiAlSi2O6) was observed and progressing of particle growth was noticed at 1 hour of soaking. Effect of thermal shock resistance on sintered LAS glass ceramic was investigated through flexural strength test. The LAS glass ceramics were heat treated at varying temperatures of thermal shock (500, 600 and 700 ° C) before the flexural strength test was implemented The LAS glass ceramics were heat treated at varies of thermal shock temperature (500, 600 and 700°C) before the flexural strength was carried out. The results showed an increase of 30% of the sintered LAS glass-ceramic flexural strength at 600°C for 6 cycles of repetition.