Conductivity and Oxidation Behavior of Fe-16Cr Alloy as Solid Oxide Fuel Cell Interconnect Under Long-Stability and Thermal Cycles

Abstract

Conductivity and oxidation behavior of Fe-16Cr alloy were investigated under long-term stability operation at 750 °C and thermal cycles from room temperature to 750 °C. The results showed that the area specific resistance (ASR) of Fe-16Cr alloy increased over time and reached about 56.29 mΩ cm2 after 40,000 h of long-term stability operation at 750 °C by theoretical calculation. The ASR of Fe-16Cr remained about 11 mΩ cm2 after 52 thermal cycles from room temperature to 750 °C. The analysis of structure showed that the oxidized phase on the surface of Fe-16Cr was mainly composed of Cr2O3 and FeCr2O4 spinel phase under long-term stability operation at 750 °C. While the Cr2O3 phase was mainly observed on the surface of Fe-16Cr alloy after 52 thermal cycles, the oxidation rates of Fe-16Cr alloy were 0.0142 μm h−1 and 0.06 μm cycle−1 under long-term stability operation and under thermal cycle, respectively. The property of Fe-16Cr alloy with 2.6 mm thickness met the lifespan requirement of interconnect for solid oxide fuel cell (SOFC) stacks. The Cr element all diffused onto oxidation surface, indicating that it was necessary to spray a coating on the surface to avoid poisoning cell cathode of SOFCs. Two 2-cell stacks were assembled and tested to verify the properties of Fe-16Cr alloy as SOFC interconnect under long-term stability operation and thermal cycle condition.