Abstract
Manufacturing of MnCo2O4 spinel coatings by solution precursor plasma spraying (SPPS) was studied in order to produce thin ceramic coating on a ferritic stainless steel interconnect for SOFC’s. The main purpose to use MnCo2O4 coating in SOFC devices is to prevent the migration of harmful CrO3 and Cr2(OH)2 compounds to the triple phase barriers (TPB) of the cathode. In this study Mn(NO3)2•4H2O and Co(NO3)2•6H2O were diluted to deionized water and mixture of deionized water and ethanol at 3 M mixture rate. The solutions were sprayed on 0.5 mm thick Crofer 22 APU substrate by Sulzer Metco F4-MB plasma gun with a modified solution feeder. Microstructural characterizations for the as-sprayed coatings were done by using a field-emission scanning electron microscopy (FESEM) with SE-mode. Elemental analyses were done with energy dispersive spectroscopy (EDS) and an X-ray diffraction (XRD) was used for crystallographic studies. The coating with full equivalence of the crystallographic structure of MnCo2O4 spinel was sprayed using argon-helium plasma and water based solution. Plasma gas with hydrogen as a secondary or ternary gas and ethanol based solutions caused the formation of the mixed phases of CoO and MnCo2O4. Although the microstructures of sprayed coatings were still quite porous, the influence of relevant gun and solution parameters were found in order to improve coating denseness in further studies.
