Review on Oxidation Behavior and Chromium Volatilization of Fe-Cr-Based Interconnects at High Operation Temperatures of Solid Oxide Fuel Cells
Keywords:SOFC, interconnect, ferritic stainless steel, oxide scale, Cr volatilization
Reduction of operating temperature to the range of 600 - 800 ?C allows metallic alloys to be considered as solid oxide fuel cells (SOFCs) interconnects. Of all SOFC components, interconnects have the most stringent criteria as they are required to work in both oxidizing and reducing conditions. To date, Fe-Cr alloys are the most promising candidates owing to their good oxidation resistance, electrical conduction, and matching thermal expansion coefficient with SOFC components. Unfortunately, the alloys are susceptible to the formation of oxide scales which are (Mn,Cr)3O4 and Cr2O3 at elevated temperatures. Moreover, thermodynamic instability in the cathode environment causes Cr volatilization from the scales, which subsequently cause cell degradation. The volatilization can be retarded with the use of protective coating or specially designed alloys with tailored compositions that enhances Laves phase precipitation. The oxidation behavior of the metallic interconnects, Cr volatilization, and their relationship with the composition of metallic alloys will be discussed.