Network structure evolution and properties of CaO-MgO-Al2O3-SiO2 glass-ceramics from BaO-bearing blast furnace slag

In this study, the influence of BaO content on the network structure evolution and properties of glass-ceramics prepared from blast furnace (BF) slag was investigated based on Raman and 27Al magic angles spinning nuclear magnetic resonance (27Al MAS NMR) spectra. The crystalline phases and microstructure changes were identified through X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). The results showed that a moderate addition of BaO enhanced the relative concentrations of Q0 and Q1 in Si-based structure, with a descent in [AlO4] unit in Al-based structure, decreasing the viscosity and the migration resistance of ions. The diopside and augite were generated and the related peak intensity was greater when BaO concentration was about 3 wt %. The tiny crystal number increased and grain size reduced significantly as BaO content raised to 3 wt %, generating the densified structure with uniform distribution of crystals. However, an excessive BaO content presented the negative effects on the structure densification. When BaO content was about 3 wt %, the glass-ceramics presented the better comprehensive performances with the density of 3.115 g/cm3, flexural strength of 153.56 MPa, Vickers hardness of 7.69 GPa, and the corrosion resistance more than 96%.

Automated summary

The influence of BaO content on the network structure evolution and properties of glass-ceramics prepared from blast furnace (BF) slag was investigated. The results showed that a moderate addition of BaO enhanced the Si-based structure, decreased the Al-based structure, and improved the migration resistance of ions. The addition of BaO also resulted in the generation of diopside and augite, as well as densified structure with uniform distribution of crystals at 3 wt % BaO content.