Effect of BaO on thermal and mechanical properties of alkaline earth borosilicate glasses with and without Al2O3

• Published in: Physica. B, Condensed matter Condensed matter, 2019-10, Vol.571, p.76-86
• Main Authors: Bhattacharya, Soumalya, Shashikala, H.D.
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Barium oxides; Boron oxides; Borosilicate glass; Calcium oxide; Compacts; Dilatometry; Endurance; Glass; High temperature; Indentation; Mechanical properties; Micro-hardness; Modulus of elasticity; Pellets; Sealants; Shrinkage; Silicon dioxide; Sintering; Temperature; Thermal expansion; Thermodynamic properties; Young's modulus
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2019.06.065

BaO-CaO-Al2O3-SiO2 (BCAS) glass and their derivatives have gained extreme importance for their high endurance to elevated temperatures and suitability for various electrochemical applications. Two glass systems, one being 50 mol%[SiO2-B2O3]-xBaO-(45-x)CaO-5Al2O3 with x = 0, 10, 20, 25, 30, 35 and 40 mol%, represented as BCBSA and another without Al2O3 termed as BCBS, synthesized using melt quenching technique are considered here. The authors focus on the thermal and mechanical properties of these glasses. Reducing BaO concentrations improve the coefficient of thermal expansion (CTE/α) and other characteristic temperatures of glasses. Compacted glass pellets made of the water quenched frits show maximum shrinkage at 700 °C. Dilatometric analysis were conducted on compacts showing maximum shrinkage. CTE of these pellets are more than the bulk glasses. Glasses with low BaO concentrations exhibit high hardness and Young's modulus. Glasses bearing 20 mol% BaO, or even lesser, meet the thermal and mechanical properties required for high temperature sealants. •Effect of varying BaO from 0 mol% to 40 mol%, in BCAS glasses, with and without Al2O3, on thermal and mechanical properties, were investigated.•Compacted glass pellets were produced and sintered at 650 °C, 700 °C, 800 °C and 900 °C, to observe their shrinkage behaviour.•Coefficient of Thermal Expansion (CTE) was determined for all bulk glasses as well as the glass compacts that showed maximum shrinkage, on sintering.•Microhardness (HV) of the glasses were determined using Vicker’s Indentation technique.•Young’s Modulus (E), Fracture toughness (KIC) and Brittleness (B) were calculated using Makishima-Mackenzie method.•Glasses bearing Thermal and Mechanical properties suitable for high temperature sealant applications were obtained.