Effect of Cu on the diffusion behavior and electrical properties of Ni-Co conversion coating for metallic interconnects in solid oxide fuel cells

Abstract The Ni-Co and Ni-Co-Cu alloy coatings, as the interconnect for solid oxide fuel cells, were fabricated on the SUS430 substrate by electroplating to reduce the oxide growth kinetics and outward diffusion of Cr. Ni-Co and Ni-Co-Cu alloy coatings were oxidized at 800 °C for 1000 h. Our experimental results indicated that the Cu addition improved the electrical behavior of Ni-Co alloy coating. Cu doping reduced the activation energy (Ea) of electrons hopping and inhibited the growth of Cr2O3 oxide layer. Furthermore, the oxidation kinetics and electrical properties of the Ni-Co and Ni-Co-Cu alloy coatings were obtained. These results showed that the Ni-Co-Cu coated steels achieved the minimum parabolic rate constant (1.82 × 10−14 g2cm−4s−1) and area specific resistance (13.44 mΩ·cm2) after the thermostatic oxidation process.