Effect of calcium fluoride on sintering behaviour of SiO2-CaO-Na2O-MgO glass-ceramic system

The crystallization characteristics of glasses based on the SiO2-CaO-Na2O-MgO (SCNM) system containing calcium fluoride (CaF2) have been investigated by differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The partial replacement of CaO by CaF2 in the studied glass-ceramics led to the development of different crystalline phase assemblages, including wollastonite and diopside using various heat-treatment processes. With the increase of CaF2 content, the crystallization temperature of the glass and the strength of the crystallization peak temperature decreases. Addition of CaF2 up to 6.0 mol%, as expected, improved the sinterability. This sample reached to maximum density by sintering at 950 °C.