Thermal expansion matching and oxidation resistance of Fe–Ni–Cr interconnect alloys

Potential interconnect alloys of Fe–Cr and Fe–Ni–Cr were fabricated via extrusion of metal oxide pastes followed by heat treatment in hydrogen. Thermal expansion of the different alloys was measured and compared with that of yttria-stabilized zirconia (YSZ). Oxidation experiments were performed in air at 700 °C using cyclic heating and weighing, as well as thermogravimetric analysis. Additions of chromium to a Fe50Ni alloy were found to improve oxidation resistance although the performance of Fe–Ni–Cr compositions was inferior to Fe–Cr alloys of similar chromium content. The improvement in oxidation behavior with increasing chromium content of the Fe–Ni–Cr alloys was contrasted with the negative impact of the chromium addition on thermal expansion matching with YSZ. Binary Fe–Cr alloys such as Fe20Cr appear to be better suited for use as a SOFC interconnect compared with Fe42.5Ni15Cr and other similar Fe–Ni–Cr alloys.