Enhanced performance of Zn-modified (MnCo)_1.5O₄ spinel coatings: Investigating critical properties for SOFC interconnect materials

Zn_xMn_1.5-0.5xCo_1.5-0.5xO₄ (ZMCO) powders were synthesized using a solid-state method and applied to 460 FC stainless-steel interconnects via electrophoretic deposition for solid oxide fuel cell (SOFC) applications. A reduction-oxidation heat treatment at 800 °C was used to densify the coating while maintaining compatibility with SOFC operating temperatures. X-ray diffraction analysis confirmed the reversible phase transformation of ZMCO spinel into MnO and Co metal during reduction, followed by spinel reformation upon oxidation. EPMA results demonstrated the coating's effectiveness as a Cr diffusion barrier. The composition with x = 0.2 exhibited optimal electrical conductivity through enhanced small polaron hopping mechanism. Thermal expansion coefficient (TEC) measurements revealed excellent compatibility between the ZMCO coatings and conventional SOFC interconnect materials. These findings indicate that ZMCO coatings, particularly at x = 0.2, are promising candidates as protective layers for SOFC interconnects.