Long-term effects of soft-chromising Ni-electroplated AISI 441 commodity steel for SOC stack interconnects

Abstract

Using commodity steel AISI 441 with Ni-based oxide coatings can facilitate large-scale interconnect manufacturing for solid oxide cell stacks, but adverse Ni-diffusion limits the high-temperature suitability. As a remedy, chromium is here added to the steel by a soft-chromising treatment. The (cyclic) oxidation resistance of virgin and soft-chromised AISI 441 is evaluated up to 8300 h at 780 °C, and further benchmarked against more commonly used Crofer 22 APU, with a Co(Mn)-spinel coating. Results revealed lowest isothermal oxidation kinetics for the soft-chromised, Ni-coated AISI 441, further preventing oxide spallation otherwise observed during thermal cycling of the virgin AISI 441 counterpart.