SrO-Containing Diopside Glass-Ceramic Sealants for Solid Oxide Fuel Cells: Mechanical Reliability and Thermal Shock Resistance

Abstract

A series of glasses and glass-ceramics (GCs) aiming at applications as sealants for solid oxide fuel cells (SOFCs) were synthesized by partial substitution of Ca for Sr in the diopside-Ba disilicate composition. X-ray diffraction in conjunction with the Rietveld-RIR technique were employed to quantify the crystalline (diopside and Sr-diopside) and amorphous phases in the glasses sintered/heat treated at 850 degrees C in humidified 10%H-2-90%N-2 gas mixture for 250h. Weibull modulus varied in the range 11.6-34.4 implying toward good mechanical reliability of synthesized GCs. Thermal shock resistance of model electrochemical cells made of yttria-stabilized zirconia, gadolinia-doped ceria, and lanthanum gallate based solid electrolytes, hermetically sealed by one diopside-based composition, was evaluated employing quenching from 800 degrees C in air and water. Suitable thermal expansion coefficient, mechanical reliability, and strong adhesion to stabilized zirconia and metallic interconnects, are all suggesting a good suitability of the sealants for SOFC applications.