Protective-conducting coatings based on black glasses (SiOC) for application in Solid Oxide Fuel Cells

The main aim of the presented study was to investigate the possibility of application of one of the newest group of materials - black glasses, in the form of protective-conducting coatings on metallic interconnects in Solid Oxide Fuel Cells (SOFC). Materials, obtained using the sol-gel method, with use of novel silsesquioxanes precursors, were deposited on ferritic stainless steel Crofer 22APU substrate via dip-coating and then heat-treated in protective atmosphere of argon at 800 °C. Structural studies of the resulting coatings i.e. XRD and MIR confirm formation of black glass structure while microstructural studies i.e SEM with EDS allowed to assess their compactness and homogeneity. The effectiveness of black glass coatings in the protective role was evaluated by the oxidation kinetics tests performed for 100 h in a laboratory air atmosphere at 800 °C in isothermal conditions. Additional microstructural studies (SEM with EDS and XRD) of both surfaces and cross-sections of the tested samples, after treatment in the simulated aggressive working environment of SOFC, proved protective properties of the investigated materials. The electrical properties of coatings were studied with the use of direct current (DC) two-probe four-point technique at temperatures ranging from 500 to 800 °C, showing an acceptable level of the area-specific resistance of the oxidized coatings around 0.1 [Ω·cm2]. The presented results show that the black glass-based protective-conductive coatings have a significant potential in the proposed application.