Thermophysical properties and devitrification of SrO-La2O3-Al2O3-B2O3-SiO2-based glass sealant for solid oxide fuel/electrolyzer cells

Thermal behaviors and stability of glass/glass-ceramic-based sealant materials are critical issues for high temperature solid oxide fuel/electrolyzer cells. To understand the thermophysical properties and devitrification behavior of SrO-La2O3-Al2O3-B2O3-SiO2 system, glasses were synthesized by quenching (25 - X)SrO-20La(2)O(3)-(7+X)Al2O3-40B(2)O(3)-8SiO(2) oxides, where X was varied from 0.0 mol% to 10.0 mol% at 2.5 mol% interval. Thermal properties were characterized by dilatometry and differential scanning calorimetry (DSC). Microstructural studies were performed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). All the compositions have a glass transition temperature greater than 620 degrees C and a crystallization temperature greater than 826 degrees C. Also, all the glasses have a coefficient of thermal expansion (CTE) between 9.0 x 10(-6) K-1 and 14.5 x 10(6) K-1 after the first thermal cycle. La2O3 and B2O3 contribute to glass devitrification by forming crystalline LaBO3. Al2O3 stabilizes the glasses by suppressing devitrification. Significant improvement in devitrification resistance is observed as X increases from 0.0 mol% to 10.0 mol%. (c) 2008 Elsevier B.V. All rights reserved.