Aluminosilicate-based sealants for SOFCs and other electrochemical applications - A brief review

abstract

Among different designs of solid oxide fuel cells (SOFCs), planar design is the most promising due to easier fabrication, improved performance and relatively high power density. In planar SOFCs and other solid-electrolyte devices, gas-tight seals must be formed along the edges of each cell and between the stack and gas manifolds. For a sealant to work effectively in high-temperature SOFC environment, equilibrium needs to be achieved amid its mechanical properties and flow behavior so that it does not only maintain its hermeticity at high temperature but is also able to reduce mechanical stresses generated in the seal during thermal cycling. The most common sealants based on glass or glass-ceramic materials have been shown to operate in fuel cells for more than 1000 h with no significant degradation. Analysis of the current literature sources demonstrated that from thermal and chemical stability points of view, silicate based glass systems are more suitable than borate and borosilicate glass systems. In this work, different glass-ceramic (GC) compositions based on alkaline- and alkaline-earth aluminosilicate-based glass systems are reviewed with a special emphasis on their thermal, chemical, mechanical, and electrical properties. Based on these considerations, glass composition design approaches are provided that aid in search of the best seal glasses satisfying the rigid functional requirements. Among all the glass systems studied, a pyroxene based CaO-MgO-SrO-BaO-La2O3-Al2O3-SiO2 seal GC compositions have been specifically discussed because those have achieved appropriate thermal and chemical properties along with high stability. Approaches for further developments and optimization of GC sealants are briefly discussed. (C) 2013 Elsevier B.V. All rights reserved.

keywords

OXIDE FUEL-CELLS; GLASS-CERAMIC SEALANT; STRUCTURE-PROPERTY RELATIONSHIPS; SEALING GLASS; CRYSTALLIZATION KINETICS; METALLIC INTERCONNECT; PLANAR SOFCS; MECHANICAL-PROPERTIES; CHEMICAL INTERACTIONS; STRUCTURAL-PROPERTIES

subject category

Chemistry; Electrochemistry; Energy & Fuels; Materials Science

authors

Tulyaganov, DU; Reddy, AA; Kharton, VV; Ferreira, JMF

our authors

acknowledgements

Important experimental contributions, partly reviewed in this work, and helpful discussions made by A. Goel, A.A. Yaremchenko, E.V. Tsipis and M.J. Pascual are gratefully acknowledged. Also authors greatefully acknowledge CICECO, University of Aveiro, Portugal, for the experimental facilities. This work was partially supported by the FCT, Portugal (projects PTDC/CTM-CER/114209/2009 and PEst-C/CTM/LA0011/2011), the Australian Research Council - Discovery Projects (No. DP110102662), and the Ministry of Education and Science of the Russian Federation (agreement No. 8649).

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