Direct Ceramic Inkjet Printing and Infiltration of Functional Coatings for Metal Supported SOFC

Direct Ceramic Inkjet Printing (DCIJP) was applied as a technology for the fabrication of anodes, electrolytes and cathodes coatings for metal-supported SOFCs. Drop-on demand electromagnetic nozzles with orifice diameter of 100 microns were utilized in dispensing nanoliter drops of suspension and sol inks with high frequency and high lateral resolution. An optimization procedure of the ink formulations and the major printing parameters was performed allowing routine production of coatings with thicknesses below 20 µm with an additional benefit of surface defects planarization. The drop-on-demand printing was also employed as a precision instrument for infiltration of the supports and the cathode scaffoldings with functional inks. Porous metal supports for SOFC applications were produced via conventional powder metallurgy routes. Commercially accessible low-cost stainless steel 430L and mixtures of NiO-Fe₂O₃ powders were chosen as source materials. The support sintering procedures was performed either in vacuum or air depending on the source material. The density and open porosity distribution of as-sintered supports were determined by Archimedes' method, optical image analysis and Hg-porosimetry. The relation between the vacuum/air sintering conditions and the micro-structural characteristics (porosity, Cr evolution, ink penetration) of the metal supports and the coatings were studied. The influence of the porosity parameters on the droplets penetration behaviour and coatings characteristics was explored. The microstructure and elemental distribution were investigated by Scanning Electron Microscope and energy dispersive X-ray spectrometry system. The analyses confirmed that DCIJP can be successfully applied for the production and modification of metal supported SOFCs.