Investigation of the Glass-Ceramic Sealants in SOFC Stacks

The stack sealing is one of the most important factors in planar solid oxide fuel cell (pSOFC) applications. In this study, the barium-silicate glass with addition of Al2O3 were analyzed by ICP, DSC, and SEM. Differential thermal analysis was utilized to design the heat-treatment of the glass to obtain a glass-ceramic for sealing. The glass material and sealing process were verified on the 114×114 mm SOFC stack. A tight stack was obtained with a leak rate much better than the desired 0.004 SCCM/cm, which is equivalent to 0.001 MPa/s. A good electric performance was also found for a 6-layer sealed stack. Post-characterization was conducted for the seal dismounted from the stack via the methods of leakage inspection, SEM-EDS, and XRD. A good interaction was found between the glass-ceramic seal and the steel interconnect, due to the diffusion of aluminum from the glass component.