Article, 2022

Effects of interdiffusion in nickel coated AISI 441 steel

Materials Characterization, ISSN 1873-4189, 1044-5803, Volume 194, Page 112413, 10.1016/j.matchar.2022.112413

Contributors

Cavichiolo, Louis Sadowski (Corresponding author) [1] [2] Nørby, Tobias Holt [1] Pantleon, Karen 0000-0001-9317-324X [2] Hald, John 0000-0002-1487-0897 [2]

Affiliations

  1. [1] Topsoe A/S, Power-to-X – Technology Development, Nymøllevej 66, 2800 Kongens Lyngby/Denmark
  2. [2] Technical University of Denmark
    3. [NORA names: DTU Technical University of Denmark; University; Denmark; Europe, EU; Nordic; OECD]

Abstract

Ferritic steel AISI 441, electroplated with nickel, is explored for the use as interconnects in solid oxide cell stacks. High-temperature oxidation tests are performed in air, and samples are investigated using scanning electron microscopy, energy-dispersive x-ray spectroscopy, and electron backscatter diffraction. Results revealed in-depth diffusion of nickel that promotes austenite formation during typical solid oxide cell operating temperatures accompanied by chromium depletion, grain refinement, and an enhanced depletion of Laves phase in the surface-near region of the steel. Effects of a formed interdiffusion zone on the protective oxide scale are discussed, considering the role of diffusion along grain boundaries and across the scale/alloy interface. The interdiffusion zone alters the morphology and continuity of Si-rich oxide that forms in this steel, and an underlying mechanism is suggested. Associated implications on the expected performance of nickel coated AISI 441 as interconnects for solid oxide cell stacks are postulated: Although no corrosion or scale spallation is observed and a good contact to the simulated oxygen electrode is maintained, there are signs of limited oxidation resistance and scale adhesion, which potentially affect lifetime and robustness of solid oxide cell stacks during (cyclic) oxidation of longer exposure than tested here.

Keywords

AISI, Laves phase, Si-rich oxide, X-ray spectroscopy, adhesion, air, austenite formation, backscatter diffraction, boundaries, cell operating temperature, cell stack, chromium, chromium depletion, coated AISI, contact, continuity, corrosion, depletion, diffraction, diffusion, effect, effect of interdiffusion, electrode, electron, electron backscatter diffraction, electron microscopy, energy-dispersive X-ray spectroscopy, enhanced depletion, exposure, ferritic steel AISI, formation, grain, grain boundaries, grain refinement, high temperature oxidation test, interconnection, interdiffusion, interdiffusion zone, interface, lifetime, limited oxidation resistance, mechanism, microscopy, morphology, nickel, operating temperature, oxidation, oxidation resistance, oxidation tests, oxide scale, oxygen electrode, performance, phase, promote austenite formation, protective oxide scale, refinement, region, resistance, results, robustness, samples, scale, scale adhesion, scale spallation, scale/alloy interface, scanning electron microscopy, solid oxide cell stacks, spallation, spectroscopy, stack, steel, steel AISI, surface-near region, temperature, test, zone

Funders

  • Innovation Fund Denmark

Data Provider: Digital Science

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