Preparation and high-temperature performance of Co10Mn and Co40Mn alloy coatings for solid oxide fuel cell metal interconnects

Co40Mn and Co10Mn alloy coatings were prepared by using high-energy micro-arc alloying process (HEMAA) and then oxidized to form oxide layers. Microstructures and compositions of CoMn coatings after preparation and oxidation were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Two sets of coating parameters were used for coating preparation and the effects of individual coating parameters and CoMn composition on coating deposition were discussed based on energy consumption and mass-transfer characteristics of different electrode materials. XRD results showed the presence of Co with dissolved Mn and Fe. Oxide scales of both coatings prepared by using set 1 parameters were composed of CoFe2O4 and hematite at 800 °C, and exhibited good adherence with the substrate and high oxidation resistance. While oxide scales of coating samples deposited by set 2 parameters were mainly (Co,Mn)3O4 and Mn3O4 for Co40Mn coating, and (Co,Mn)3O4 and CoFe2O4 for Co10Mn coating. Continuous spinel oxide layer was not found at 800 °C in air for all coatings. Oxide scales with high content of Co and Mn experienced breakaway when cooled to room temperature. All the CoMn coatings efficiently suppressed Cr outward diffusion and the values of area specific resistance (ASR) were measured to be low.