Barium Borosilicate Sealing Glasses Synthesized by a Sol-Gel Process: Chemical Interactions with a Stainless Steel and Gas-Tightness of a SOFC

摘要

Several glasses synthesized by sol-gel route and based on the BaO-B2O3-X-Al2O3-SiO2 (X = CaO, MgO) glass system have been investigated to evaluate their applicability as sealant for solid oxide fuel cell (SOFC). Chemical interactions with K41X stainless steel and hydrogen-tightness of these materials were evaluated after operations at high temperatures over 1,000 h in air atmosphere. Formation of a new phase at the steel-glass interface and formation of porosity in the glass were observed and determined as critical problems over mid-term operations. The role of MgO is important to obtain a gas-tight sealing. Application of the glass paste without binder addition was performed in order to avoid possible residual porosity related problems. The best glass was finally used as sealant between anodic and cathodic compartments in complete SOFCs operated at 760 and at 800 degrees C. Open circuit voltages and power densities of the cells were recorded during the first hours of operation.