Nano-CeO2 and -LaCrO3 dispersed ferritic stainless steels as potential interconnect materials for solid oxide fuel cells

Novel nano-oxide dispersed ferritic stainless steel alloys have been developed as potential interconnect materials for solid oxide fuel cells. Nanopowders of CeO2 and LaCrO3 were mixed with ferritic stainless steel powder (SUS430) using conventional ball milling. Rectangular pellets were prepared and sintered at 1400 °C in pure H2. The microstructural analysis of the sintered pellets showed a uniform distribution of oxide particles. Long-term area specific resistance (ASR) of the pellets was monitored using the four-probe DC method at 800 °C for 1000 h in air, revealing that an increase in the CeO2 amount from 0.5 to 3 and 5 wt % increased the oxidation resistance of the steel. ASR values as low 32.2 and 5.5 mΩ cm2 were observed, respectively, for 3 and 5 wt % nano-CeO2 dispersed SUS430 steel. However, in the case of LaCrO3 addition, no such relationship between the oxidation resistance and LaCrO3 concentration was found. This study showed that the dispersed nano-CeO2 particles effectively reduced the Cr2O3 scale growth, likely by retarding the inward diffusion of oxygen, hence resulting in a high oxidation resistance at the SOFC operating conditions.