Performance evaluation of several commercial alloys in a reducing environment

Several commercial alloys including Ebrite, Crofer 22 APU, Haynes 230 and Haynes 242, which are candidates for intermediate-temperature solid oxide fuel cell (SOFC) interconnect materials, were isothermally and cyclically oxidized at 900 °C in the reducing atmosphere of Ar + 5 vol.% H2 + 3 vol.% H2O corresponding to the SOFC anode environment. Results indicate that these alloys exhibited good scale spallation resistance with the Ni-base alloys possessing better oxidation resistance over the Fe-base alloys. Both Mn–Cr spinel and Cr2O3 were formed in the oxide scales of these alloys. For Crofer 22 APU and Haynes 242, a continuous protective MnO and Mn–Cr spinel layer formed outside on the inner layer of Cr2O3. The increase in scale ASR after longer-term thermal exposure in the reducing environment was relatively slower for the Ni-base alloys than for the Fe-base alloys.