Iron doped manganese cobaltite spinel coatings produced by electrophoretic co-deposition on interconnects for solid oxide cells: Microstructural and electrical characterization

We report a systematic microstructural and electrical characterization of iron doped Mn-Co spinel coatings processed by electrophoretic co-deposition of Mr(0)(.5)Co(1.5)O(4) and Fe2O3 powders on Crofer 22 APU and AISI 441 steel substrates. Iron addition to Mn-Co spinel coating leads to a reduction of the area specific resistance on both substrates, after 3200 h at 750 degrees C. The Fe doped Mn-Co coating both leads to a thinner oxide scale and reduces the sub scale oxidation for the Crofer 22 APU substrate. Fe doped Mn-Co on AISI 441 shows both a thicker oxide scale and low area specific resistance values, likely due to a doping effect of the oxide scale by minor alloying elements. The different mechanisms by which iron doping of Mn-Co spinels can influence elemental interdiffusion at the steel-oxide scale-coating interfaces and relative contributions to the overall area specific resistance are evaluated by means of advanced electron microscopy. The promising results are further confirmed in a cell test, where the Fe doped MnCo coated interconnect does not induce any degradation of the oxygen electrode, proving its efficiency.