Evaluation of Haynes 242 alloy as SOFC interconnect material

Ni-based alloy Haynes 242 with low coefficient of thermal expansion (CTE) was evaluated as a candidate material for solid oxide fuel cell (SOFC) interconnect application in this paper. Short-term isothermal oxidation tests at 700, 800 and 900 °C in air indicated that the oxidation kinetics of Haynes 242 obeyed the parabolic law and the weight gain of the alloy increased with the increase in oxidation temperature. The oxides formed on it consisted of an outer layer of NiO and an inner layer of Cr2O3 with (Mn,Cr)3O4 spinel; however, the top NiO layer did not uniformly cover the surface of the sample. The long-term isothermal and cyclic oxidation resistance of this alloy at 800 °C in air was similar to that of current interconnect alloys Ebrite and Haynes 230, and better than that of Crofer. The area specific resistance (ASR) of the surface oxides formed on Haynes 242 was comparable to that of Haynes 230, and lower than that of Ebrite and Crofer after similar thermal exposures. Based on the experimental results, the potential of Haynes 242 as interconnect material of intermediate temperature SOFC was discussed.