Sealing glass of barium-calcium-aluminosilicate system for solid oxide fuel cells

Glass-ceramic materials were developed as a sealant in the solid oxide fuel cell (SOFC) in the temperature range of 800 similar to 850 degrees C. The glass materials were based on the glass and glass-ceramic in the BaO-CaO-Al2O3-SiO2-La2O3-B2O3 system. The thermal expansion coefficient (TEC) decreased with lower Ba2+ content and higher Ca2+ content, but the glass transition temperature and crystallization temperature increased greatly with an increase in Ca2+ content and a decrease in Ba2+ content, when the other components in the sealant were invariable. The TEC of the sealant with Ba2+ content of 25.4% was 10.8 x 10(-6) K-1 (temperature range from 25 to 850 degrees C), and its softening temperature was 950 degrees C. The TEC of the sealant accorded well with that of La0.9Sr0.1Ga0.8Mg02O3-6(LSGM) with a mismatch of only 3%. The sealant had superior stability and compatibility with the LSGM electrolyte during the process of operation in SOFC. The weight loss of the sealant with Ba2+ content of 25.4% was approximately zero after heat-treated at 800 degrees C for 500 h in H-2 and O-2 atmosphere, respectively.