Enhancing high-temperature suitability of Ni-electroplated AISI 441 steel by soft-chromising

Commodity ferritic steel AISI 441, electroplated with nickel, can improve large-scale interconnect manufacturing for solid oxide cell stacks, but nickel-diffusion-induced chromium depletion in the steel surface adversely affects the oxidation behaviour. The present study explores soft-chromising to limit oxidation in Ni-coated AISI 441 during a simulated stack sealing exposure. Complementary in-situ X-ray diffraction and ex-situ electron microscopy revealed that soft-chromising favours the formation of protective external Cr(Mn)-rich oxide and lowers detrimental internal oxidation. Soft-chromising seems promising for the development of new low-cost commodity steels that allow nickel in protective coatings, thereby facilitating an interconnect design appropriate for large-scale production.