MODELLING OF CHROMIUM CONTAMINATION OF SOFC CATHODES FROM METALLIC INTERCONNECTS

A Zwetanova, M Machkova, M Christov, A Zwetanova, M Machkova, M Christov
2007 Journal of the University of Chemical Technology and Metallurgy   unpublished
Solid oxide fuel cells, SOFCs, offer excellent environmental performance compared to power generation technologies that rely on combustion. Intermediate temperature solid oxide fuel cells stacks operating at 600-800 o C may enable the use of inexpensive metallic alloys as interconnect material. In the last decade for this purpose ferritic steels with high contents of chromium are designed and investigated. Against their implementation however is the evaporation of chromia, formed on the
more » ... rmed on the interconnect surface at high temperature and preventing it from corrosion. The volatile Cr-species penetrate into the ceramic cathode form solid phase and block the active sites where oxygen is reduced, thus worsening the stack performance. The aim of this study is a modeling of the transport process in gas phase from the IC to the cathode surfaces. In first approximation it is divided into diffusion and flow drift. The diffusion coefficient of the prevailing species are estimated according to the kinetic gas theory. Calculation of the amount of Cr reaching the cathode is done for interconnect channels with square cross section in a planar SOFC stack, on the basis of thermodynamically treated evaporation process.
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