Evaluation and Application of a Novel BaO-CaO-SiO2-CoO-B2O3 Based Glass-Ceramic Sealing Material for Solid Oxide Fuel Cells

Sealant is used in a solid oxide fuel cell (SOFC) stack to separate fuel and oxygen from burning with each other throughout the stack's lifetime cycle. Various sealing materials have been developed and the glass sealant shows quite a potential for its low leaking rate. However, glass sealants usually suffer from fractures during thermal cycle because of their low-temperature brittleness and mismatched coefficient of thermal expansion. Recently, we have developed a novel glass-based sealant consisting of BaOCaO-SiO2-CoO and a small amount of Al2O3 powder which is used to adjust the coefficient of thermal expansion (CTE) and reinforce its mechanical performance. The sealant exhibited a good performance with the leaking rates less than 0.04 sccm cm(-1) under compressive load of 0.17 MPa at 750 degrees C and showed stable leak rates over several thermal cycles. The well bonded interfaces and chemical compatibility have been identified by microstructure analysis of the seals. The sealant also demonstrated its applicability in a one-cell stack test.