Ni‐Containing Conducting Ceramic as an Oxidation Protective Coating on Metallic Interconnects by Aerosol Deposition

Abstract

Thick (∼5 μm) conducting perovskite LaNiO3 films were deposited on ferritic stainless steel (SS) by aerosol deposition (AD) for use as an oxidation resistance coating layer in the metallic interconnector of a solid oxide fuel cell (SOFC). The microstructural evolution and electrical resistivity of the LaNiO3‐coated SS at the SOFC operating temperature (800°C) were examined. The coated oxide layers were fairly dense without pores or cracks, and good adhesion was maintained, even after oxidation at 800°C for 1000 h. The interface oxides formed between LaNiO3 and SS consisted of Ni and Mn‐containing spinel and a Cr‐rich oxide layer. The initial area specific resistance (ASR) of the LaNiO3‐coated SS was 2.68 mΩ·cm2, which was increased to 7.34 mΩ·cm2 after post heat treatment at 800°C for 1000 h. The ASR of the LaNiO3‐coated SS was ∼30% lower than that of the (La0.8Sr0.2)MnO3‐coated SS post heat treated for the same time. Ni2+ substitution for Mn3+ in the octahedral sites of the spinel structures appears to decrease the resistivity of the interface oxide layer, and increase the long‐term stability of the ASR at high temperatures.