Electrical conductivity of interconnects in presence of two manganese spinel coatings

Intermediate temperature solid oxide fuel cells(SOFCs) allow the use of ferritic stainless steel interconnect. The bare plates can not remain the electrical conductivity after long term oxidation. The purpose of this work was to investigate the electrical conductivity of AISI 430 stainless steel which was coated in a Co-base pack mixture by pack cementation method. Coated samples were characterized using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). Electrical conductivity of the coated substrates was tested as a function of temperature by annealing the samples from room temperature to 800°C. Also electrical conductivity has been investigated as a function of oxidation time during isothermal oxidation at 800°C. Results showed the increase of temperature caused to the decrease of electrical conductivity and also, X-ray diffraction pattern revealed, that the coating layer converted to Mn₃O₄ and MnFe₂O₄ spinels during isothermal oxidation. These spinels improved electrical conductivity of coated substrates (54.7 S.cm⁻¹) compared to uncoated substrates (27.7 S.cm⁻¹) after 200 h oxidation at 800°C.