MATERIAL CHARACTERIZATION IN SUPPORT OF THE DEVELOPMENT OF AN ANODE SUBSTRATE FOR SOLID OXIDE FUEL-CELLS

A new design for solid oxide fuel cells (SOFC's) was developed aiming at the reduction of the total electrical resistance of the cell. The t hickness of the electrolyte was decreased, while the anode took on the role of the substrate. The pore structure with respect to gas permeab ility of this component has to be optimized for the proper operation o f this design, Anode substrates, consisting of a cermet (yttrium-stabi lized ZrO2 and metallic Ni) and produced by two different processes, c oat mix and tape casting, were characterized with respect to pore stru cture (shape and mean radius), porosity (total, open and permeable), p ore size distribution and air permeability. The following methods were used: (i) optical and electron scanning microscopy in combination wit h image analysis, (ii) mercury porosity, and (iii) air permeability. C orrelations between air permeability and porosity and also the percent age of permeable pores in anodes show the superiority of coat mix samp les to tape-cast ones. It has been observed that the coat mix process can produce anode substrates with interconnecting porosity, while tape casting, as used in this study, needs some modifications in order to be appropriate for this purpose.