Effect of SiO2/MgO ratio on the crystallization behavior, structure, and properties of wollastonite-augite glass-ceramics derived from stainless steel slag

Wollastonite-augite glass-ceramics of the CaO–SiO2–Al2O3–MgO system were prepared from stainless steel slag as the main raw material. The effects of SiO2/MgO mass ratio on the crystallization behavior, crystalline phases, structure, and properties of the as-prepared stainless steel slag glass-ceramics were investigated by differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, and physicochemical property measurements. The results showed that with decreasing SiO2/MgO ratio, the crystallization activation energies of the samples decreased from 436.48 kJ/mol to 383.84 kJ/mol, and their crystallization indexes increased from 1.67 to 3.21; in addition, the augite crystals were gradually refined and their content increased. On the other hand, the amount of elongated wollastonite crystals decreased and the crystals gradually dispersed in the augite crystals. Furthermore, among all the prepared glass-ceramics, the one with a density of 3.08 g/cm3 exhibited the best mechanical properties with a bending strength of 176.21 MPa and microhardness of 8.81 GPa. [Display omitted] •Wollastonite-augite glass-ceramics were derived from stainless steel slag.•Augite crystals were refined and their content increased with decreasing SiO2/MgO.•Two-dimensional volumetric crystallization was major crystallization mode in samples.