Fabrication of Functionally Graded SOFC by APS
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JTTEE5 16:768–775 DOI: 10.1007/s11666-007-9132-6 1059-9630/$19.00 ASM International 2007
Fabrication of Functionally Graded SOFC by APS Y.Z. Yang, H.O. Zhang, G.L. Wang, and W.S. Xia (Submitted March 3, 2007; in revised form June 6, 2007) Atmospheric plasma spray (APS) was used to prepare the planar positive/electrolyte/negative (PEN) and mono-block layer built (MOLB) type PEN solid oxide fuel cells (SOFCs). On the basis of the spraying conditions optimized previously and the self-developed functionally graded powder feeder system, two types of PEN cells were fabricated. Then the microstructure and material composition of the PEN cells were analyzed. The results show that graded layers formed between the electrodes and electrolyte. Moreover, the material composition and the porosity of the graded layers vary gradually. In particular, the porosities of the resultant anode and cathode reach 32.74 and 32.24%, respectively. Using the AC complex impedance technique, the conductivity of the MOLB type composite electrode is tested. The electrical conductivity of the MOLB type composite electrode with the graded layers is larger than that without the graded layers.
Keywords
atmospheric plasma spray, electrical conductivity, functionally graded layers, PEN, SOFC
1. Introduction The solid oxide fuel cell (SOFC) has drawn keen attention because of its high energy efficiency, low environmental hazards, high power density, and excellent integration with a simple reformer. Thus, SOFC is expected to realize commercialization within a few years and be a promising candidate for future energy conversion systems in the 21st century (Ref 1-3). However, the status of the development is still at a moderate level, and some key technical issues have not been resolved yet. Generally, intermediate-temperature SOFCs operate under high-temperature conditions (600 to 1000 C). The strict bonding among each cell component results in mechanical constraints; thus a slight mismatch in the coefficient of thermal expansion (CTE) of cell components causes large thermal stress (Ref 4). As a conseThis article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 1416, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain Montavon, Ed., ASM International, Materials Park, OH, 2007. Y.Z. Yang, G.L. Wang, and W.S. Xia, State Key Laboratory of Material Processing and Die & Mould Technology, Huazhong University of Science & Technology, Wuhan 430074, P.R. China; and H.O. Zhang, State Key Laboratory of Digital Equipment and Manufacturing Technology, Huazhong University of Science & Technology, Wuhan 430074, P.R. China. Contact e-mail: [email protected].
768—Volume 16(5-6) Mid-December 2007
quence, CTE matching among the cell components is indispensable to reduc
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