Thermal properties of sodium borosilicate glasses as a function of sulfur content
Sulfur trioxide (SO3) additions, up to 3.0 mass%, were systematically investigated for effects on the physical properties of sodium borosilicate glass melted in air, with a sulfur–free composition of 50SiO2–10Al2O3–12B2O3–21Na2O–7CaO (mass%). Solubility measurements, using electron microscopy chemic...
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Published in | Journal of the American Ceramic Society Vol. 103; no. 6 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Ceramic Society
08.02.2020
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Subjects | |
Online Access | Get full text |
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Summary: | Sulfur trioxide (SO3) additions, up to 3.0 mass%, were systematically investigated for effects on the physical properties of sodium borosilicate glass melted in air, with a sulfur–free composition of 50SiO2–10Al2O3–12B2O3–21Na2O–7CaO (mass%). Solubility measurements, using electron microscopy chemical analysis, determined the maximum loading to be ~1.2 mass% SO3. It was found that measured sulfur (here as sulfate) additions up to 1.18 mass% increased the glass transition temperature by 3%, thermal diffusivity by 11%, heat capacity by 10%, and thermal conductivity by 20%, and decreased the mass density by 1%. Structural analysis, performed with Raman spectroscopy, indicated that the borosilicate network polymerized with sulfur additions up to 3.0 mass%, presumably due to Na2O being required to charge compensate the ionic $SO$ $^{2–}_{4}$ additions, thus becoming unavailable to form non–bridging oxygen in the silicate network. It is postulated that this increased cross–linking of the borosilicate backbone led to a structure with higher dimensionality and average bond energy. This increased the mean free paths and vibration frequency of the phonons, which resulted in the observed increase in thermal properties. |
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Bibliography: | NE0008597 USDOE Office of Environmental Management (EM) USDOE Office of Nuclear Energy (NE), Nuclear Energy University Program (NEUP) |
ISSN: | 0002-7820 1551-2916 |
DOI: | 10.1111/jace.17057 |