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.