Journal of the American Ceramic Society, Vol.94, No.3, 861-866, 2011
Chemical Compatibility Investigation of Thin-Film Oxygen Transport Membranes on Metallic Substrates
Thin-film La0.58Sr0.4Co0.2Fe0.8O3-delta (LSCF58428) exhibits high oxygen permeability due to its high ionic and electronic conductivity. In order to increase the oxygen flux, a thin-film membrane on a structural substrate is beneficial. Different Ni-based alloys were studied as potential substrate materials. The chemical compositions and thermal expansion coefficients of Ni-based alloys were measured in this study. LSCF58428 layers were screen printed on Ni-based alloys and cofired at a high temperature in air. Microstructural and elemental analyses of samples were conducted using a scanning electron microscope and energy-dispersive X-ray spectroscope. X-ray diffraction was used to investigate the phase compositions. The Ni-based alloy, MCrAlY (with M=Ni, Co), with a high Al content showed better chemical compatibility with perovskite material at high temperatures than other Ni-based alloys. A reaction occurred between Sr in the perovskite and the alumina-based surface layer on MCrAlY. However, the reaction zone was found to be stable in mid-term annealing at 800 degrees C in air. Hence, it is expected that this reaction will not prevent application as an oxygen transport membrane. Three different cofiring atmospheres were investigated. Air was found to be the only possible cofiring atmosphere.