An alkali-free barium borosilicate viscous sealing glass for solid oxide fuel cells

An alkali-free, alkaline earth borosilicate glass (designated G102) has been developed as a viscous sealant for use with solid oxide fuel cells (SOFCs). The glass possesses the requisite viscosity, electrical resistivity, and thermal and chemical stability under SOFC operating conditions to act as a reliable sealant. Sandwich seals between aluminized stainless steel and a YSZ/NiO-YSZ bilayer survived 148 thermal cycles (800 °C to room temperature) in both oxidizing and reducing atmospheres at a differential pressure of ∼3.4 kPa (0.5 psi) without failure. For sandwich seals that were held at 800 °C for up to 2280 h in air, G102 resisted crystallization, there were limited interactions at the G102/YSZ interface, but BaAl2Si2O8 crystals formed at the glass/metal interface because of the reaction between the glass and the aluminized steel. Sandwich seals that were intentionally cracked by thermal shock resealed to became hermetic upon reheating to temperatures as low as 744 °C.