Performance investigation of Li2O–Al2O3–4SiO2 based glass–ceramics with B2O3, Na3AlF6 and Na2O fluxes

Abstract

Influence of single fluxes (10wt.% B2O3), bi-component fluxes (4wt.% B2O3+6wt.% Na3AlF6), and complex fluxes (4wt.% B2O3+4wt.% Na3AlF6+2wt.% Na2O) on the thermal kinetic parameters, microstructure, flexural strength and coefficient of thermal expansion (CTE) of Li2O–Al2O3–4SiO2 (LAS) glass–ceramics was investigated through differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The results showed that complex fluxes could efficiently decrease transition temperature (Tg) and crystallization temperature (Tp), and accelerate the formation of needle-like β-spodumene crystals which benefit high flexural strength. The homogeneous LAS glass–ceramic (sample C3) which has a high strength of 132.4MPa and low CTE (100–650°C) of 2.74×10−6/°C is obtained by doping of the initial LAS glass by complex fluxes of 4wt.% B2O3, 4wt.% Na3AlF6, and 2wt.% Na2O, nucleating at 630°C/120min and then crystallized at 780°C/120min. It is worthy of further investigation as a bonder of diamond composite material due to its outstanding prosperities.