Sintering/Crystallization and Viscosity of Sealing Glass-Ceramics

Two glass-ceramics sealants for solid-oxide fuel cells (SOFC) in the system BaO/SrO-MgO-B2O3-SiO2 have been analysed according to relevant sealing parameters such as sintering and crystallization of the glass powders and dilatation and viscosity evolution with crystallization of glass-ceramic compacts. Special emphasis is given to the crystallization kinetics and mechanism, crystalline phases formed and the role of viscosity in the whole sealing process. The slower crystallization rate of the strontium-containing glass composition results in good joining with the interconnect steel before the glass starts to crystallize and increases its viscosity. This avoids and excessive sealing temperature and offers better compatibility with the start up and working temperature of an SOFC (750–850 °C).