Stability of Oxidation Resistance of Ferritic Fe-Cr Alloy for SOFC Interconnects

Abstract

Ferritic Fe-Cr alloy is suitable for an interconnect material of planar-type SOFC. A ferritic Fe-22Cr alloy with a small addition of La and Zr, ZMG232, which has good oxidation resistance and good electrical conductivity at 750-1000 degrees C, was developed as a metallic interconnect material. Recently, further long-term stability of oxidation resistance of interconnect material has been required. Therefore in order to improve the oxidation resistance of ZMG232, the effect of alloying elements on properties of ferritic Fe-Cr alloys was investigated. As a result, it was found that oxidation resistance and electrical contact resistance of ZMG232 were improved by decreasing Si and Al contents. The oxidation test was carried out in air at 750 degrees C for 5000 hours. The oxidation weight gain of ZMG232L, which was an improved alloy with low Si and Al contents, reduced by about 30% in comparison with that of ZMG232.