Microstructural transformations of two representative slags at high temperatures and effects on the viscosity

The transformation of the Si-Al microstructures of slags, which have similar SiO2 + Al2O3 and CaO contents but different SiO2/Al2O3 ratios, was quantified using multinuclear SS-NMR. Three kinds of Si Qn microstructures (Q2, Q3, and Q4), where n denotes the number of bridging oxygen linked to other Si atoms for each Q (SiO4) unit, and one Al structure (Al (IV)) were present in both slags. The Q3 percentage in two slags was increased as increase of temperature from 1200 to 1600 °C. The transformation of Si-Al microstructures was interpreted by a hypothetic model of cristobalite cluster based on the crystal and Qn structure.