Effect of Ni–Mo addition on cyclic and isothermal oxidation resistance and electrical behavior of ferritic stainless steel for SOFCs interconnect

• Presence of Mo formed Laves- phase in the oxide/metal interface.
• Presence of 2 wt% Ni was effective to the position of the Laves-phase formation.
• Inward diffusion of oxygen was reduced by Ni and Mo addition.
• Ni and Mo addition were effective to enhance the oxidation resistance.
• Presence of Ni and Mo reduced the electric resistance and the Cr evaporation rate.

Ni and Mo were added to ferritic stainless steel to improve the properties of the oxidation, electrical conductivity and Cr evaporation rate. The purpose of making this alloy was for application in solid oxide fuel cells (SOFCs) interconnect. Therefore, the cyclic and isothermal oxidation tests were performed and the area-specific resistance (ASR) and the Cr evaporation rate were investigated. The microstructure was discussed by scanning electron microscope (SEM). Glow discharge spectrometry (GDS) and X-ray were used for elemental and phase analysis, respectively. The addition of 3 wt% Mo reduced the oxidation rate and the Cr evaporation resistance by the formation of Laves-phase in oxide/metal interface. By reducing the activity of Fe in the steel, Mo was prevented outward diffusion of cations and anion diffusivity. Furthermore, Mo improved the electrical conductivity by filling the gaps and voids in the oxide/metal interface. The addition of 2 wt% Ni reduced the distribution of Laves-phase particles in substrate and the particles were moved to side oxide/metal interface and neighboring areas to it. Ni also improved the oxidation resistance and electrical conductivity in the steel.