Effect of additives on the thermal properties and sealing characteristic of BaO-Al2O3-B2O3-SiO2 glass-ceramic for solid oxide fuel cell application

The apparent densities, coefficients of thermal expansion (CTE), and softening points of the BaO-Al₂O₃-SiO₂-B₂O₃ glasses prepared in this study range from 2.61 to 3.92 g/cm³, 4.92 to 10.98 ppm/°C, and 656 to 854 °C, respectively, depending on the glass composition. The softening point decreases with increasing BaO or B₂O₃ content in the glass. The feasibility of using MgO, KAlSi₂O₆, and KAlSiO₄ to tune the CTE of BaO-Al₂O₃-SiO₂-B₂O₃ glass is investigated. Composites containing MgO additive show little change in CTE at high temperature and report a high structural stability with the change in time. Wetting angle of the glass on the YSZ substrate depends to a great extent on the soaking temperature and the BaO content in the glass. Composites of selected BaO-Al₂O₃-SiO₂-B₂O₃ glasses and MgO additive on the YSZ substrate are evaluated for use as sealing material of solid oxide fuel cells (SOFCs). Results indicate that leakage rates for the composites of L06-20 vol% MgO, L08-30 vol% MgO, and L09-40 vol% MgO are lower than the detectable limit in this study.