Viscosity and liquidus temperature of quaternary glasses close to an eutectic composition in the CaO–MgO–Al2O3–SiO2 system

• Published in: Journal of materials science Vol. 52; no. 13; pp. 8280 - 8292
• Main Authors: Veit, Ulrike, Rüssel, Christian
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.07.2017; Springer Nature B.V
• Subjects: Aluminum oxide; Calcium oxide; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Crystallography and Scattering Methods; Eutectic composition; Exchanging; Glass; Liquidus; Magnesium oxide; Materials Science; Original Paper; Polymer Sciences; Raw materials; Silicon dioxide; Solid Mechanics; Temperature; Thermodynamic properties; Viscosity; X-ray fluorescence; Glass Composition; Network Modifier; Liquidus Temperature; Calcium Oxide; Al2O3
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-017-1044-3

The thermal properties of the quaternary glass-forming CaO–MgO–Al 2 O 3 –SiO 2 system were evaluated. Different glass compositions with an expected liquidus temperature—the lowest temperature at which both the crystal phase and the melt are thermodynamically stable—below 1300 °C were melted from pure raw materials. Each oxide concentration did not deviate by more than ±3 mol% from that of the centre glass composition of 61.2 SiO 2 , 26.3 CaO, 8.6 Al 2 O 3 and 3.8 MgO. Viscosity data and the liquidus temperatures were determined, as well as the exact compositions of the respective glasses by X-ray fluorescence. It was of special interest for this study, whether small compositional changes have a stronger influence on T Liq or T 3 . The T 3 -values, which are the temperatures attributed to a viscosity of 10 3  dPa s—showed a much larger variation and are in the range from 1263 to 1363 °C. An exchange of the network formers Al 2 O 3 or SiO 2 by network modifiers CaO and MgO resulted in a decrease in viscosity. The effect of MgO was also shown by a comparison with glasses of similar compositions but without any MgO. The exchange between Al 2 O 3 and SiO 2 did not show a significant difference in viscosity whereas the substitution of CaO by MgO increased the viscosity. The liquidus temperature varied between 1137 and 1192 °C—less than expected for a composition close to an eutectic system.