Preparation and Properties of Porous Zirconia/Nickel Composites

Porous zirconia/nickel composites were prepared from yttria-stabilized zirconia, nickel and corn-starch powder as starting materials in reduced condition. In expectation of the application to the anode of the solid oxide fuel cell, mechanical and thermal properties of composites with different porosity levels were measured. With increasing additive corn-starch as the pore-former, the porosity of the composites with continuous and constant-sized pores increased. Larger nickel particles were observed in the zirconia network structure. The fracture strength and toughness decreased with increaseing porosity. Especially, the connected pores and cracks at the interface between nickel and zirconia particles have a large effect on the strength of the composites. The specific heat of the porous composites was constant almost. The thermal conductivity increased with nickel content but decreased with the porosity. The latter phenomenon was discussed by assuming a minimum matrix area model or a network model.