Synthesis and Characterization of Nanocrystalline MnCo2O4-δ Spinel for Protective Coating Application in SOFC

Abstract

Nanocrystalline (40-50 nm) powders of MnCo2O4-δ spinel have been synthesized through combustion technique at a relatively low temperature. The fuel to oxidant ratio has been optimized by carrying out the combustion reaction under various redox conditions (i.e. varying fuel : nitrate ratio) using different fuels viz., citric acid and glycine. A controlled combustion of the complex gel is achieved under a fuel lean condition using a mixed fuel of glycine and citric acid. Phase pure materials are obtained upon calcination of the ash at a temperature as low as 650degC and the powder can be consolidated to more than 95% of theoretical density at a temperature of only 1100degC. The bulk samples show a linear thermal expansion behaviour (CTE: 13.1 x 10-6 K-1) and a high electrical conductivity (>100 S/cm at 800degC). Crofer22APU interconnect plates are deposited with the synthesized powder using electrophoretic deposition (EPD) technique for protective coating application.