Oxide film formation and diffusion processes in near-surface layers of current collectors in solid oxide fuel cells

A method is developed for modifying the surface of current collectors in solid-oxide fuel cells (SOFC) prepared from ferrite stainless steel (Crofer22APU). Diffusion of the protective coating material into the Crofer22APU bulk and reverse diffusion of steel components into the coating are studied. The cross-sectional microstructure and composition are studied by the electron-microscopic technique. The elemental composition of the junction between the current collector and the lanthanum-strontium manganite cathode is studied depending on the time of service-life tests in the SOFC working mode (50–6000 h). The formation of the Cr₂O₃ oxide islet structure on the current collector surface at the steel/coating interface is observed. It is shown that the mutual diffusion of coating components (Ni) and Crofer22APU steel together with the redox reaction at the interface prevent the chromium diffusion to the surface and protect the steel current collector from oxidation.