Co-Electrodeposition of Ni/Co–W and Cu/Co–W Alloys on Type 445 Stainless Steel for Application in SOFC Interconnects

Abstract

The objective of this study was to investigate the oxidation resistance and area specific resistance at high temperature of Ni/Co–W and Cu/Co–W electroplated type 445 stainless steels using co-electrodeposition. Coated samples were exposed to oxidation at a high temperatures 800 °C in air containing 3 vol.% water vapour for 96 h. X-ray diffraction analysis revealed that the oxidation process resulted in the formation of CoWO₄ and Co₃O₄ on the Ni/Co–W sample, and CoWO₄, Co₃O₄, CuWO₄ and CoCr₂O₄ on the Cu/Co–W sample. The Ni/Co–W coated sample effectively suppressed the outward diffusion of chromium. The Cu/Co–W coated sample exhibited a higher oxidation rate than the Ni/Co–W coated sample. The oxidation kinetics of the coated samples obeyed the parabolic rate law. The Cu/Co–W coated sample exhibited a lower area specific resistance compared to the Ni/Co–W coated sample.