Optimization of the rheology and sintering behavior of electrolyte and anode pastes to be used in co-extrusion of solid oxide fuel cells

Typical electrolyte paste including Yittria Stabilized Zirconia (YSZ) and anode paste containing YSZ, NiO, starch/activated carbon (pore former) were prepared. In order to perform co-extrusion process the pastes must have nearly same rheological properties. So, the prepared pastes unified in order to have same rheological characteristics using the Benbow–Bridgwater model. The unification results showed a linear relationship between the required liquid content for paste preparation and weight percentage of NiO powder in unified pastes. Such a linear relationship can be used to predict the required liquid content of the intermediate anode pastes. The unified pastes were extruded as single layer tubes and sintered at various experimental conditions. Micro-structural features of the sintered tubes were investigated using Scanning Electron Microscope (SEM) and optimum sintering temperature and time were found as 1450 °C and 2 h, respectively for full electrolyte densification. Moreover, 30 wt% of carbon may be regarded as the optimum carbon content for creating enough porosity in the anode layers.