Viscosity and Liquidus Temperature of Ternary Glasses Close to the Eutectic Composition in the CaO–Al2O3–SiO2 System

Thermal properties of ternary glass‐forming systems within the known CaO–Al 2 O 3 –SiO 2 system were evaluated. Different glass compositions near the lowest eutectic composition (around a liquidus temperature of 1170°C) within the CaO–Al 2 O 3 –SiO 2 system were melted from pure raw materials. The investigated target range of compositions in wt% was between 60.5 and 63.5 SiO 2 , 13.1 and 16.1 Al 2 O 3 , and 21.4 and 25.4 CaO. The chemical compositions, the glass transition temperatures, and the temperatures attributed to viscosities of 10³ dP a*s were determined experimentally. It was of special interest to obtain information of all these properties of the glasses and the effect of small composition changes hereon. The liquidus temperature changed less than expected for a composition close to the eutectic composition. Temperatures at a viscosity of 10³ dP a*s varied between 1263 and 1363 °C ± 6°C. A liquidus temperature of 1157°C ± 7°C (with a confidence interval of 95%) of the eutectic composition was found. The results reported here may be useful for understanding and improvement of the modeling within the CaO–Al 2 O 3 –SiO 2 glass system.