Preparation of aliened porous Ni-GDC nano composite by freeze-casting process

This current study reports preparation of Nickel-Gadolinium doped Ceria (Ni-GDC) composite via controlled unidirectional freeze casting of aqueous-based GDC slurry completed with nickel infiltrated into the porous GDC samples. Gadolinium doped ceria powder prepared by gel-combustion synthesis method. The oxide powder was confirmed to be the fluorite-structured of Ce0.8Gd0.2O1.9 solid solution by X-ray diffraction. The synthesized powder with dolapix as a dispersant, ammoniac as an agent pH, poly vinyl alcohol (PVA) as a binder and water as a solvent were used to prepare stable GDC slurries.  Freeze casting process was done in different solid loading of GDC at 35, 45 and 44 wt. %, and two different rates of 1 and 3 ̊C/min to obtain desirable pore structure. After removing the frozen ice at -58 ̊C the green samples were sintered for 2 h in air at 1300 °C. The pore structure and final microstructure were studied by scanning electron microscopy. The porosity of the sintered samples was in a range of 60-70% , and were depended on solid content and freeze casting rate.  Finally nickel solution was infiltrated into hierarchically porous GDC samples, after reduction at 800 ̊C, Ni-GDC composite was attained.