The planar design of solid oxide fuel cell (SOFC) is the most promising one dueto its easier fabrication, improved performance and relatively high powerdensity. In planar SOFCs and other solid-electrolyte devices, gas-tight sealsmust be formed along the edges of each cell and between the stack and gasmanifolds. Glass and glass-ceramic (GC), in particular alkaline-earth aluminosilicate based glasses and GCs, are becoming the most promising materials forgas-tight sealing applications in SOFCs. Besides the development of newglass-based materials, new additional concepts are required to overcome thechallenges being faced by the currently existing sealant technology. Thepresent work deals with the development of glasses- and GCs-based materialsto be used as a sealants for SOFCs and other electrochemical functionalapplications. In this pursuit, various glasses and GCs in the field of diopsidecrystalline materials have been synthesized and characterized by a wide arrayof techniques. All the glasses were prepared by melt-quenching techniquewhile GCs were produced by sintering of glass powder compacts at thetemperature ranges from 800−900 ºC for 1−1000 h. Furthermore, the influenceof various ionic substitutions, especially SrO for CaO, and Ln2O3 (Ln=La, Nd,Gd, and Yb), for MgO + SiO2 in Al-containing diopside on the structure,sintering and crystallization behaviour of glasses and properties of resultantGCs has been investigated, in relevance with final application as sealants inSOFC. From the results obtained in the study of diopside-based glasses, a bilayeredconcept of GC sealant is proposed to overcome the challenges beingfaced by (SOFCs). The systems designated as Gd−0.3 (in mol%:20.62MgO−18.05CaO−7.74SrO−46.40SiO2−1.29Al2O3 − 2.04 B2O3−3.87Gd2O3)and Sr−0.3 (in mol%: 24.54 MgO−14.73 CaO−7.36 SrO−0.55 BaO−47.73SiO2−1.23 Al2O3−1.23 La2O3−1.79 B2O3−0.84 NiO) have been utilized to realizethe bi-layer concept. Both GCs exhibit similar thermal properties, while differingin their amorphous fractions, revealed excellent thermal stability along a periodof 1,000 h. They also bonded well to the metallic interconnect (Crofer22APU)and 8 mol% yttrium stabilized zirconium (8YSZ) ceramic electrolyte withoutforming undesirable interfacial layers at the joints of SOFC components andGC. Two separated layers composed of glasses (Gd−0.3 and Sr−0.3) wereprepared and deposited onto interconnect materials using a tape castingapproach. The bi-layered GC showed good wetting and bonding ability toCrofer22APU plate, suitable thermal expansion coefficient (9.7–11.1 × 10–6K−1), mechanical reliability, high electrical resistivity, and strong adhesion to theSOFC componets. All these features confirm the good suitability of theinvestigated bi-layered sealant system for SOFC applications.
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