Abstract
Ferritic stainless steels are promising candidates for interconnect applications in low- and mid-temperature solid oxide fuel cells (SOFCs). A couple of issues however remain for this particular application, including chromium poisoning due to chromia evaporation, and long-term surface and electrical stability of the scale grown on these steels. Application of a manganese colbaltite spinel protection layer on the steels appears to be an effective approach to solve the issues. For an optimized performance, properties of Mn 1+x Co 2-x O 4 (-0.5≤x≤1.5) spinels relevant to the protective coating application were investigated. It was found that the spinels with x around 0.5 demonstrated a good CTE match to ceramic cell components, high electrical conductivity, and thermal stability up to 1,250°C. The material suitability was confirmed by a long-term test on a Mn 1.5 Co 1.5 O 4 protection layer that was thermally grown on Crofer22 APU, indicating the spinel protection layer not only significantly decreased the contact resistance between a LSF cathode and a stainless steel interconnect, but also inhibited the sub-scale growth on the stainless steel.
Published Version
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