Effects of CaO/SiO2 ratio and CaCl2 content on the densification, microstructure, and properties of sintered CaO-MgO-Al2O3-SiO2-CaCl2 glass-ceramic

The effects of CaO/SiO2 ratio (basicity) and CaCl2 addition amount on the properties of CaO-MgO-Al2O3-SiO2-CaCl2 glass-ceramics (GC) were investigated. When sintered at 825 °C, the increase in basicity from 0.35 to 0.75 reduced the porosity of GCs from 1.1 to 0.8 vol%, but the increase of CaCl2 addition amount from 5 to 10 wt% increased the porosity from 0.8 to 7.0 vol%. The main crystalline phase of GC changed from augite (Ca(Mg0.7Al0.3)(Si1.7Al0.3)O6) to Ca10Al12Cl2Si5O37 by increasing the CaCl2 addition amount to 7.5 wt%. The increase in CaCl2 addition had adverse effects on the bending strength and Vickers hardness, while the rise in basicity deteriorated the bending strength but had little impact on the Vickers hardness. This study may have a guiding significance for preparing slag-based GCs and treating CaCl2-containing wastes.