Oxidation kinetics and phase evolution of a Fe-16Cr alloy in simulated SOFC cathode atmosphere

摘要

The oxidation behavior of a Fe-16Cr alloy containing a small amount of Mn oxidized in air for up to 500 h within the temperature range of 650-850 deg C was examined. Two consecutive oxidation stages were found and these obeyed the parabolic rate law with various rate constants. Formation and growth of Cr_2O_3, MnCr_2O_4, surface nodules and oxide spallation were found to be responsible in the oxidation stages accordingly to various situations. The thin film X-ray diffraction, SEM and EDX confirmed the duplex oxide microstructure with MnCr_2O_4 on top of Cr_2O_3, Cr and Mn diffusion in Cr_2O_3 is considered to be responsible for the formation of each layer, respectively. The estimated area specific resistance (ASR) suggests the possibility of using this alloy as the interconnect material in reduced temperature SOFCs, however, surface modification to enhance its oxidation and spallation resistances is desired.