A model is presented that enables viscosities to be predicted reliably over the whole range of compositions and temperatures in the Al₂O₃-CaO-MgO-SiO₂ slag system above liquidus in the temperature range from 1543 K to 2643 K (1270 °C to 2370 °C). Experimental procedures and data from the studies reported in the literature have been collected and critically reviewed with particular attention to the viscometry methods and possible contamination of slag samples to select reliable data points for further model development. Relevant revised formalism to describe the complex viscosity trends including charge-compensation effect of the Ca²⁺ and Mg²⁺ cations on the formation of tetrahedrally coordinated Al³⁺ was introduced. Parameters of the quasi-chemical viscosity model have been optimized to reproduce within experimental uncertainties most of the selected experimental data in the Al₂O₃-CaO-MgO-SiO₂ system and all subsystems. This study is part of the overall development of the self-consistent viscosity model of the Al₂O₃-CaO-FeO-Fe₂O₃- MgO-Na₂O-SiO₂ multicomponent slag system.

Porous glass was prepared by the hydrothermal reaction of sodium borosilicate glass, and oxygen-ion characterization was used to identify the hydroxyl groups in its surface area. A substantial amount of “water” was introduced into the ionic structure as either OH⁻ groups or H₂O molecules through the hydrothermal reaction. When the hydrothermally treated glass was reheated at normal pressures, a porous structure was formed due to the low-temperature foaming resulting from the evaporation of H₂O molecules and softening of the glass. Although it was expected that the OH⁻ groups would remain in the porous glass, their distribution required clarification. Oxygen K-edge X-ray absorption fine structure (XAFS) spectroscopy enables the bonding states of oxygen ions in the surface area and interior to be characterized using the electron yield (EY) and fluorescence yield (FY) mode, respectively. The presence of OH⁻ groups was detected in the O K-edge XAFS spectrum of the porous glass prepared by hydrothermal reaction with a corresponding pre-edge peak energy of 533.1 eV. In addition, comparison of the XAFS spectra obtained in the EY and FY modes revealed that the OH⁻ groups were mainly distributed in the surface area (depths of several tens of nanometers).