Effect of TiO {sub 2} on thermal, structural and sealing properties of BaO-Al {sub 2} O {sub 3}-B {sub 2} O {sub 3}-SiO {sub 2}-La {sub 2} O {sub 3} glass and glass ceramics

摘要: BaO-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3} -SiO{sub 2} glass compositions with different additives like CaO, MgO, La{sub 2}O{sub 3} have been reported as potential materials for high temperature sealants in solid oxide fuel cells (SOFC). While they exhibit overall good thermo-physical properties, their thermal expansion coefficient (TEC), crystallization behavior need to be optimized to ensure phase stability and chemical bonding at high operating temperature (800 deg C). In the present work, we have investigated the effect of TiO{sub 2} on TEC, activation energy of crystallization (E{sub a}), evolution of crystalline phases and bonding with Crofer 22APU alloy which is normally used as interconnect in planar SOFC. The glasses with nominal compositions (in mol%) 34BaO-10AI{sub 2}O{sub 3} -17B{sub 2}O{sub 3}-34SiO{sub 2}-(5-x)La{sub 2}O{sub 3}-(x)TiO{sub 2}, where x=0,1,2,3,4 were prepared by melt quenching process. Calcined charge was melted in a Pt crucible at about 1550 deg C and then poured in suitable graphite mould followed by annealing at 550 deg C to remove the thermal stresses induced by rapid quenching.