TG measurements of the oxidation kinetics of Fe-Cr alloy with regard to its application as a separator in SOFC

The high-temperature oxidation behavior of a ferritic alloy (SUS 430) in a SOFC environment, corresponding to the anode (H-2/H2O gas mixture) and cath ode (air) operating conditions, was determined with regard to application o f the alloy as a metallic separator material in SOFC. The oxidation kinetic s of Fe-16Cr alloy (SUS 430), was studied by thermogravimetry in H-2/H2O ga s mixtures with p(H2)/p(H2O)=94/6 and 97/3 and in air, in the temperature r ange 1023-1223 K, for 3.6 up to 1080 ks. It and was found that the protecti ve oxide scale, composed mainly of Cr2O3 with uniform thickness and excelle nt adhesion to the metal substrate, grows in accordance with the parabolic rate law. The dependence of the parabolic rate constant, k(p), of the scale on temperature obeys the Arrhenius equation: k(p)=6.8x10(-4) exp (-202.3 k J mol(-1)R(-1)T(-1)) for H-2/H2O gas mixtures with p(H2)/p(H2O)=94/6. The d etermined kp was independent of the oxygen partial pressure in the range fr om 5.2x10(-22) to 0.21 atm at 1073 K, which means that the rates of growth of the scale on Fe-16Cr alloy in the above-mentioned atmospheres are compar able. The oxidation test results on Fe-16Cr alloy in H-2/H2O gas mixtures a nd air demonstrate the applicability of SUS 430 alloys as a separator for S OFC.