SOFC Anode Fabricated by Magnetically Aligning of Ni Particles

Ni particles are aligned by magnetic field during the drying process after screen-printing Ni/8YSZ (yttria-stabilized zirconia) paste. By applying a magnetic field, Ni particles are magnetically polarized, attracted to each other, and align along the magnetic field. It is proposed, that not only tortuosity of Ni but also that of YSZ and of pores is decreased. Symmetrical half cells are fabricated with 15-μm-thick anodes and 200-μm-thick YSZ electrolytes. A current collector made of porous Ni with a thickness of approximately 5 μm was printed on top of each anode. The microstructural changes in the anodes are analyzed by scanning electron microscopy. Impedance measurements are performed at 700°C in H2/H2O atmospheres containing 10% and 60% H2O. The initial polarization resistance was decreased after applying a magnetic field of 100 mT by up to 25%. However, with higher magnetic field, the polarization resistance increases, which might be explained by a pronounced increase of the surface roughness with 30 μm peak-to-valley, causing current constriction.