Ruddlesden–Popper nickelate as coating for chromia-forming stainless steel

• Ruddlesden–Popper nickelate, La2NiO4+δ, is used as protective coating for metallic interconnect of SOFC
• This material absorbs the Cr species to form La(Ni,Cr)O3 perovskite.
• No spalling is observed during the phase transition and the ASR of the interconnect is 2.5 mΩ cm2.

A Ruddlesden–Popper nickelate, La2NiO4+δ (LN), is examined as a coating material for metallic interconnects of a solid oxide fuel cell (SOFC) operating at intermediate temperatures. Isothermal oxidation of the coated and uncoated SS430 alloy with and without pre-annealing at 850 °C in air suggests that the coating reduces significantly the oxidation rate and impact of thermal cycle on the integrity of the scale. After an annealing in air at 850 °C for 50 h, the LN coating has turned into to La(Cr,Ni)O3 (LCN) perovskite, but no spalling is observed because of the matching thermal expansion of LN and LCN to SS430. A low area specific resistance (ASR) of 2.5 × 10−3 Ω cm2 is observed for the sample with the resultant LCN coating, indicating LN can be a good candidate as a coating for interconnects of SOFC.

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