Effect of CaO/SiO_2 mass ratio on the properties of glass ceramics containing 10% Al₂O₃ from blast furnace slag,tailing and coal fly ash

Blast furnace slag, tailing and coal fly ash were used as starting materials for preparing glass-ceramics by the sintering method based on their characteristics and without adding any other nucleating and chemical agents. The effects of CaO/SiO₂ mass ratio and crystallization temperature on the crystaltransition, crystallization behavior and main mechanical properties of slag glass-ceramics with 10% Al₂O₃were systematically investigated by differential thermal analysis, X-ray diffraction and scanning electron microscopy. When the CaO/SiO₂ mass ratio increases, the crystallization activation energy decreases, the Si-O tetrahedral bonding strength decreases, the particle movement strengthens, and the crystallization onset temperature and the crystallization temperature decrease. The glass samples with a CaO/SiO₂ mass ratio of 0.4, sintered at 886℃ for 1 h as a nucleation process and at 982℃ for 1 h as a crystalli-zation process, possess the best performance with the bending strength of 103.59 MPa, the microhardness of 5.3 GPa and the acid and alkali resistances of 0.25% and 〈 0.1% (mass loss rate) respectively. Moreover, the major phase of the glass ceramics is diopside.