Preparation of Aligned Porous Ni-GDC Nano Composite by Freeze-Casting Process

This study reports preparation of nickel-gadolinium doped ceria (ni-gdc) composite via controlled unidirectional freeze casting of aqueous-based gdc slurry completed with nickel infiltration into the porous gdc samples. gadolinium doped ceria powder was prepared by gel-combustion synthesis method. the oxide powder was confirmed by x-ray diffraction to be the fluorite-structured of ce_0.8gd_0.2o_1.9 solid solution. the synthesized powder was used with dolapix as a dispersant, ammonia solution as an agent ph, poly vinyl alcohol (pva) as a binder and water as a solvent to prepare stable gdc slurries. freeze casting process was done in different solid loadings of gdc at 35, 45 and 55 wt. %, and two different cooling 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 range of 60-70% , and depended on solid content and freeze casting rate. finally, nickel solution was infiltrated into the hierarchically porous gdc samples, after reduction at 800 ̊c, ni-gdc composite was attained.