Glass-Ceramic Sealants for Planar IT-SOFC: A Bilayered Approach for Joining Electrolyte and Metallic Interconnect

Abstract

To develop suitable sealants for planar anode-supported intermediate temperature solid oxide fuel cells (IT-SOFC) operating at around , several glass-ceramic compositions based on the system have been prepared and investigated. Thermal, chemical, and electrical properties of the glass ceramics along with crystallization behavior and bonding characteristics of parent glasses with yttria-stabilized zirconia (YSZ) electrolyte and ferritic steel-based interconnect Crofer22APU are studied. The glass transition temperatures of the developed glasses are within . By varying the alkaline-earth metal content, the coefficient of thermal expansion (CTE) values can be tailored between that of YSZ and Crofer22APU. Based on the crystallization behavior, a single glass seal having matching CTE with Crofer22APU and a bilayer glass seal having different CTE values within the range of are found to be effective for metal–metal and metal–electrolyte sealing, respectively. The electrical resistivities of the sealants are quite high , and under sandwiched condition between two metals, the developed glasses are found to maintain this high resistivity even after of operation. A low helium leak rate value has been observed for most of the developed glasses.