Oxidation behavior of a Ni-Fe support in SOFC anode atmosphere

In this work, we investigated the long-term oxidation behavior of a Ni-Fe (1:1 weight ratio) support for solid oxide fuel cell (SOFC) applications. Ni-Fe supports were obtained through tape casting, high temperature sintering and pre-reducing in 97% H₂/N₂ (9/91)-3% H₂O at 750 and 1000 °C, respectively. Then the Ni-Fe supports were exposed in simulated anode atmospheres of 97% H₂/N₂ (9/91)-3% H₂O and 75% H₂/N₂ (9/91)-25% H₂O for periods of up to 1000 h at 750 °C. The samples were examined for mass change, phase and chemical composition, and microstructure evolution during the annealing process. The Ni-Fe supports exposed to H₂/N₂-3% H₂O showed negligible oxidation, while those exposed to H₂/N₂-25% H₂O showed a 4–6% mass increase, due to the fact that a Fe-rich oxide scale was found on the surface of the Ni-Fe alloy particles. Room-temperature conductivity measurements showed that the supports annealed in the two atmospheres maintained sufficiently high conductivity. The results from the current work demonstrate that the porous Ni-Fe support can be well employed in SOFCs, especially metal-supported SOFCs.