Ni–Fe alloy coatings with Nb contents of 0, 4.2 at.%, 7.0 at.% and 9.0 at.% were electrodeposited on ferritic stainless steels for intermediate-temperature solid oxide fuel cell (SOFC) interconnect application. The oxidation behavior, scale-growth mechanisms and electrical performances of the Ni–Fe- and NiFe–Nb-coated steels were then investigated in air at 800 °C corresponding to the cathode environment of SOFC. It was found that the scales formed are mainly composed of an external NiFe2O4 layer and an inner Cr2O3-rich layer after oxidation, with some Nb-rich oxides also observed for the Nb-containing coatings. Doping 4.2 at.%Nb into the coating decreased the growth rate of Cr2O3 and suppressed the formation of voids at the scale/alloy interface, whereas excess Nb impaired the oxidation resistance of the steel. The Nb addition affects the oxide growth direction by suppressing the cation transport. All the coatings decreased the area-specific resistance (ASR) of the steel, with the NiFe–4.2 at.%Nb-coated sample exhibiting the lowest ASR value. The effects of Nb on the oxidation mechanism and electrical properties of the Ni–Fe-coated steels are discussed.

中文翻译：

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Nb添加量对铁素体不锈钢NiFe2O4尖晶石涂层高温性能的影响

在铁素体不锈钢上电沉积 Nb 含量为 0、4.2 at.%、7.0 at.% 和 9.0 at.% 的 Ni-Fe 合金涂层，用于中温固体氧化物燃料电池 (SOFC) 互连应用。然后在对应于 SOFC 阴极环境的 800 °C 空气中研究了 Ni-Fe 和 NiFe-Nb 涂层钢的氧化行为、氧化皮生长机制和电性能。发现氧化后形成的氧化皮主要由外部NiFe2O4层和内部富Cr2O3层组成，在含Nb涂层中也观察到一些富Nb氧化物。在涂层中掺杂 4.2​​ at.%Nb 会降低 Cr2O3 的生长速率并抑制氧化皮/合金界面处空隙的形成，而过量的 Nb 会削弱钢的抗氧化性。添加 Nb 通过抑制阳离子传输影响氧化物生长方向。所有涂层都降低了钢的面积电阻率 (ASR)，NiFe–4.2 at.%Nb 涂层样品的 ASR 值最低。讨论了 Nb 对 Ni-Fe 涂层钢的氧化机制和电性能的影响。