Improved reoxidation tolerance of Ni–Fe metal support for LaGaO3 thin film electrolyte cell

Effects of reoxidation and reduction treatment of a Ni–Fe metallic anode substrate were investigated as a function of reoxidation period and temperature. The NiFe2O4 composite anode substrate was highly dense before the reduction treatment. However, after reduction for 2 h in H2 atmosphere, the dense oxide composite substrate was changed to a porous metal substrate consisting of a Ni–Fe alloy. The metallic substrate was then reoxidized in 100% O2. When the reoxidation treatment was performed, the porous substrate regained its original density. However, XRD patterns of the reoxidized substrate still exhibited strong Ni base alloy peaks. Moreover, SEM–EDX analysis showed that a large part of the reoxidized substrate was porous and a dense iron base oxide layer formed at the surface of the substrate. In addition, after reduction for 2 h with hydrogen gas, the substrate returned to a porous metal substrate again. Therefore, in spite of slightly increased anodic IR loss and a small fuel-leakage, which was observed after the reoxidation and reduction cycles, the Ni–Fe metal supported cell showed an excellent reoxidation tolerance at 973 K.