Effect of CaF2 on viscosity, structure and properties of CaO-Al2O3-MgO-SiO2 slag glass ceramics

Bayan Obo tailings (BOTs), fly ash (FAS), and stainless-steel slag (SSS) are industrial wastes that require reasonable, clean, and effective utilization for environment protection. The paper focuses on the structure and properties of glass-ceramics that were prepared by melting BOT, FAS, and SSS raw materials. The effect of CaF2 on the viscosity, structure, and performance of CaO-Al2O3-MgO-SiO2 (CAMS) slag glass-ceramics is determined by viscometer, differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and physicochemical properties measurements. The results show that moderate amounts of CaF2 facilitates depolymerization of the silicate networks, which leads to a decrease in the melting temperature, viscosity and viscous activation energy of glass. However, the content of more than 3% CaF2 results in a dramatic decreases in the chemical stability of the glass-ceramics because of the transformations of the main crystalline phase from diopside to anorthite, which is accompanied by fluorite precipitation.