Fabrication of Highly Porous Yttria-Stabilized Zirconia by Acid Leaching Nickel from a Nickel-Yttria-Stabilized Zirconia Cermet

Porous Y₂O₃-stabilized ZrO₂ (YSZ) samples were synthesized by preparing NiO/YSZ composites by tape casting and calcining at 1800 K, reducing the NiO to nickel in H₂ at 973 K, and finally leaching the nickel out of the structure with 2.2 M HNO₃ at 353 K. Porous YSZ was prepared from NiO/YSZ composites containing 0, 20, 40, and 50 wt% NiO. Complete removal of the nickel was demonstrated by XRD, weight changes, and porosity increases. Porosities >75% could be achieved without structural collapse of the YSZ phase. Finally, the method was applied to the fabrication of a solid oxide fuel cell with a copper-based anode operating on H₂ and n -butane.