Influence of Bi₂O₃ on Crystalline Phase Content and Thermal Properties of Åkermanite and Diopside Based Glass-Ceramic Sealant for SOFCs

Abstract:

Solid oxide fuel cell (SOFC) is an electrochemical energy conversion device which is considered as clean energy source generator with reliability and relatively inexpensive production cost. One of the most important components for planar design SOFC is the hermetic seal that prevents fuel from leaking out of between the stack of fuel cells. Glass-ceramics are attractive materials as sealing materials for this device. The expected coefficient of thermal expansion (CTE) of the glass-ceramic sealants should be between 9 and 12 x 10⁻⁶ K⁻¹. Glass – ceramics based on åkermanite (Ca₂MgSi₂O₇) crystalline phase were reported their high CTE value from about 10 to 11.3 x 10⁻⁶ K⁻¹. In this study, glass compositions in the CaO-MgO-B₂O₃-Al₂O₃-SiO₂ system with varying amounts of Bi₂O₃ from 0 to 10 wt. % were prepared by conventional melting and investigated their properties. The selected compositions were derived from ternary åkermanite–forsterite–anorthite phase diagram. Phase composition and quantitative phase analysis of glass–ceramics were examined by X-ray diffractometer. The onset of crystallization (T_x) and crystallization temperature (T_c) were measured by DTA. The thermal properties of bulk glass samples and heat treated samples at 900 oC for 2 h which were glass transition temperature (T_g), dilatometric softening temperature (T_s), and coefficient of thermal expansion (CTE) were determined by dilatometer. Furthermore, the long-term stability of their CTE was investigated. The samples were continued to soak at 800 °C for 100 h and observed their change in CTE value. The results found that the åkermanite phase tended to increase with increasing amount of Bi₂O₃ content.

• Periodical: Key Engineering Materials (Volume 751)
• Pages: 483-488
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.751.483
• Online since: August 2017
• Authors: Pornchanok Lawita, Apirat Theerapapvisetpong, Sirithan Jiemsirilers*
• Keywords: Barium-Free, Glass-Ceramics, Sealant, SOFC

References

[1] J.W. Fergus, Sealants for solid oxide fuel cells, J. Power. sources. 147 (2005) 46-57.

DOI: 10.1016/j.jpowsour.2005.05.002

[2] V. Kumar, A. Arora, O. Pandey, K. Singh, Studies on thermal and structural properties of glasses as sealants for solid oxide fuel cells, Int. J. Hydrogen. Energ. 33 (2008) 434-438.

DOI: 10.1016/j.ijhydene.2007.07.049

[3] N. Lahl, K. Singh, L. Singheiser, K. Hilpert, D. Bahadur, Crystallisation kinetics in AO-Al2O3-SiO2-B2O3 glasses (A = Ba, Ca, Mg), J. Mater. Sci. 35 (2000) 3089-3096.

DOI: 10.1023/a:1004851418274

[4] S.B. Sohn, S.Y. Choi, G.H. Kim, H.S. Song, G.D. Kim, Suitable Glass-Ceramic Sealant for Planar Solid-Oxide Fuel Cells, J. Am. Ceram. Soc. 87 (2004) 254-260.

DOI: 10.1111/j.1551-2916.2004.00254.x

[5] Z. Yang, Chemical interactions of barium–calcium–aluminosilicate-based sealing glasses with oxidation resistant alloys. Solid. State. Ionics. 160 (2003) 213-225.

DOI: 10.1016/s0167-2738(03)00160-7

[6] F. Smeacetto, M. Salvo, M. Ferraris, J. Cho, A.R. Boccaccini, Glass–ceramic seal to join Crofer 22 APU alloy to YSZ ceramic in planar SOFCs, J. Eur. Ceram. Soc. 28 (2008) 61–68.

DOI: 10.1016/j.jeurceramsoc.2007.05.006

[7] A. Goel, D.U. Tulyaganov, V.V. Kharton, A.A. Yaremchenko, J.M.F. Ferreira, The effect of Cr2O3 addition on crystallization and properties of La2O3-containing diopside glass-ceramics, Acta. Mater. 56 (2008) 3065-3076.

DOI: 10.1016/j.actamat.2008.02.036

[8] A. Theerapapvisetpong, S. Jiemsirilers, P. Thavorniti, R. Conradt, Barium-Free Glass-Ceramic Sealants from the System CaO-MgO-B2O3-Al2O3-SiO2 for Application in the SOFC, Mater. Sci. Forum. 695 (2011) 1-4.

DOI: 10.4028/www.scientific.net/msf.695.1

[9] O.V. Mazurin, Problems of Compatibility of the Values of Glass Transition Temperatures Published in the World Literature, Glass Phys. Chem. 33 (2007) 22–36.

DOI: 10.1134/s108765960701004x