CoFe_2O_4 spinel protection coating thermally converted from the electroplated Co-Fe alloy for solid oxide fuel cell interconnect application

摘要

CoFe_2O_4 has been demonstrated as a potential spinel coating for protecting the Cr-containing ferritic interconnects. This spinel had an electrical conductivity of 0.85 S cm~(-1) at 800℃ in air and an average coefficient of thermal expansion (CTE) of 11.80 × 10~(-6) K~(-1) from room temperature to 800℃. A series of Co-Fe alloys were co-deposited onto the Crofer 22 APU ferritic steel via electroplating with an acidic chloride solution. After thermal oxidation in air at 800℃, a CoFe_2O_4 spinel layer was attained from the plated Co_(0.40)Fe_(0.60) film. Furthermore, a channeled Crofer 22 APU interconnect electrodeposited with a 40-μm Co_(0.40)Fe_(0.60) alloy film as a protective coating was evaluated in a single-cell configuration. The presence of the dense, Cr-free CoFe_2O_4 spinel layer was effective in blocking the Cr migration/transport and thus contributed to the improvement in cell performance stability.