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Thermal properties of sodium borosilicate glasses as a function of sulfur content
Author(s) -
Lonergan Jason M.,
Lonergan Charmayne,
Silverstein Joshua,
Cholsaipant Pornsinee,
McCloy John
Publication year - 2020
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.17057
Subject(s) - borosilicate glass , raman spectroscopy , analytical chemistry (journal) , thermal diffusivity , glass transition , sulfur , chemistry , sulfur trioxide , thermal analysis , materials science , inorganic chemistry , thermal , thermodynamics , organic chemistry , polymer , sulfur dioxide , physics , optics
Sulfur trioxide (SO 3 ) 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 50SiO 2 –10Al 2 O 3 –12B 2 O 3 –21Na 2 O–7CaO (mass%). Solubility measurements, using electron microscopy chemical analysis, determined the maximum loading to be ~1.2 mass% SO 3 . 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 Na 2 O being required to charge compensate the ionic SO 4 2 -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.