Fabrication of (Mn,Co)3O4 Coating on AISI-430 Ferritic Stainless Steel by Pulse Plating and Post Oxidation

Excessive growth of surface oxide scale with high electrical resistance accompanied by spallation and chromium poisoning of the cathode are the main disadvantages of using metallic interconnects in SOFCs. The mentioned limitations reduce the interconnect lifetime and the efficiency of SOFC. Deposition of a protective coating onto interconnect is the best method to overcome the problems. Chromium-free spinels are promising materials among which Co-Mn spinel has been given a great deal of attention due to good electrical conductivity and suitable diffusion barrier against chromium. In this research، a duplex layer of Co and Mn were deposited on AISI-430 ferritic stainless steel to produce a protective/conductive coating by pulse electroplating. Post heat treatment in air at 800°C lead to inter-diffusion of Co and Mn as well as oxidation. Consequently، Co-Mn spinel coating formed on the surface. After 100 hours of oxidation، negligible Cr content (less than 0. 5%at.) was detected in the coating. Hence، applying this coating can properly control the Cr-evaporation phenomenon by preventing chromium diffusion towards the surface. Moreover، According to the XRD results، FeCrCoO4 and Mn (CrCo) O4 spinels with higher electrical conductivity than chromia are formed at the coating/substrate interface.