Cobalt plating of high temperature stainless steel interconnects

To limit oxidation and protect against loss of conductivity in stainless steel for applications such as high temperature fuel cell interconnects, a layer of cobalt was electroplated on the surface. When heated in air at 800 °C, the cobalt was converted into spinel phases containing cobalt, chromium and iron. The oxide layer was characterized by X-ray diffraction and energy dispersive spectrometry. The area specific resistance (ASR) of the samples was measured by a new technique. After 1900 h oxidation at 800 °C in air, the cobalt-coated UNS430 stainless steel had a clean surface and a stable ASR of 0.026 Ω cm2 compared to uncoated UNS430 which showed a thick, porous oxide growth and an ASR more than 10-fold higher.