The influence of Mn spinel coatings on electrical conductivity of Fe-17%Cr alloy

Chromium containing alloys are among the best candidates for solid oxide fuel cell interconnects. However, reduce of electrical conductivity during high temperature oxidation should be solved. In this study, AISI 430 ferritic stainless steel was coated in a Mn-base pack mixture by pack cementation method. As-coated specimens were characterized using scanning electron microscopy (SEM). Electrical conductivity of the coated coupons was tested as a function of temperature by oxidizing the samples from room temperature to 700°C. Also electrical conductivity has been evaluated as a function of oxidation time during isothermal oxidation at 700°C. Results showed the increase of temperature caused to the decrease of electrical conductivity and also, the coating layer transformed to manganese spinels during isothermal oxidation. Spinels ameliorated the electrical conductivity of coated coupons (69 S.cm⁻¹) compared to uncoated ones (32 S.cm⁻¹) after 200 h oxidation at 700°C.