Effects of alloyed Si on the oxidation behaviour of Co–29Cr–6Mo alloy for solid-oxide fuel cell interconnects

• Oxide scale (Cr2O3, SiO2, CoCr2O4) produced on Co–29Cr–6Mo at 700–1000 °C.
• SiO2 and CoCr2O4 particles inhibit inward O diffusion and outward Cr diffusion.
• Alloyed Si in Co–29Cr–6Mo promotes formation of continuous Cr2O3 film.
• Oxide-scale adhesion enhanced by Si addition.
• Less oxide-scale growth and spallation at higher Si concentration.

To evaluate the suitability of the Co–29Cr–6Mo alloy as an interconnect in solid-oxide fuel cells (SOFCs), the oxidation behaviour of Co–29Cr–6Mo alloys with various Si concentrations was investigated in air at 700–1000 °C. The presence of alloyed Si improved the oxide-scale adhesion by promoting the formation of a continuous Cr2O3 film. The SiO2 particles in the inner layer and the grain boundaries of alloy matrix beneath the inner layer inhibited the inward oxygen diffusion and outward chromium diffusion. The results indicate that the Co–29Cr–6Mo alloy with added Si is appropriate for SOFC applications.

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