Influence of processing conditions on the microstructure of NiO-YSZ supporting anode for solid oxide fuel cells

In the present work, the control of a ceramic colloidal process is aimed to fabricate NiO-YSZ composite with specific microstructure and porosity for anode-supported solid oxide fuel cell applications. The optimization of dispersant and solid concentration in anode slurries provides a reduction in their viscosity, shear stress and yield stress; concurrently, solvent evaporation and hysteresis in flow behaviour are minimized, thus improving the suspension stability. The corresponding sintered compacts produced from the optimized slurry demonstrated uniform microstructure with specific porosity distribution. It is shown that the residual porosity can be tailored in the range of 12–23% exclusively by controlling the conditions of drying, burn-out and sintering process; the lower limit allows effective gas permeation during anode reduction owing to an interconnected pore structure obtained already at 12–14% porosity. This indicates a stable pore structure derived from the burn-out of pore former even for sintering temperature as high as 1400 °C.