Galliosilicate glasses for viscous sealants in solid oxide fuel cell stacks: Part I: Compositional design

Galliosilicate glasses were developed for sealing intermediate temperature planar solid oxide fuel cell (SOFC) stacks. Candidate sealing glasses were identified for use at operating temperatures of 750 °C and at 850 °C after assessing flow behavior, thermal expansion properties, and crystallization behavior. A series of non-alkali glasses was identified for use at 750 °C within a strontium boro-galliosilicate compositional region that exhibited glass transition temperatures (Tg) between 658 and 675 °C and coefficients of thermal expansion (CTE) between 8 and 9.4 × 10−6 K−1. Glass frits and powders flowed below 850 °C and did not crystallize dramatically after 500 h at 750 °C. Several glasses containing 5 mol% mixed alkali were identified in a strontium boro-galliosilicate compositional region for use at 850 °C. The glasses exhibited Tg between 615 and 620 °C with CTE from 7.8 to 9.7 × 10−6 K−1. Glass frits flowed well below 850 °C and retained remnant glass phase after partial crystallization at 850 °C. The galliosilicate glasses developed in this work enable viscous sealing of SOFC stacks.