Experimental assessments on the resistance to oxidation and Cr evaporation of several Fe-Cr based alloys

Five selected alloys, Crofer22 APU, Crofer H, ss441 and two different ZMG232 were selected for a cautious study. Our major focus is on the materials' resistance to oxidation and Cr evaporation. Both issues remain to be major concerns in many applications, particularly for interconnects in solid oxide fuel cells. For the part of oxidation, samples of five alloys are placed in an oven heating at 800 C for 250 h. The microstructures, morphologies and compositions of samples after oxidation are analyzed by SEM, XRD, EDS on surfaces and cross-sections. Electrical resistance of samples during oxidation is measured by four-point probe to obtain their variations over time. An assembly, of which two alumina plates sandwiching the samples alloys, is specifically designed to test the resistance of specimens to Cr evaporation, which is gauged by the amount of deposited Cr on the two alumina plates under long-hour oxidation. Experimental results revealed that Crofer22 APU has a better performance than others after long-hour oxidation with thinner oxidized layer, lower electrical resistance and less Cr evaporation.