Physical properties of alumina/yttria-stabilized zirconia composites with improved microstructure

Abstract

Cubic stabilized zirconia is the preferred material for application as solid electrolyte in solid oxide fuel cells. However, this material has low fracture toughness, which can lead to formation of cracks during long-term operation. Moreover, increase of mechanical as well as electrical properties would be useful for cost-effectiveness of this type of device. In this context, addition of alumina to zirconia-based solid electrolyte can be an interesting option to accomplish that purpose. In this work, ceramic composites containing various amounts of alumina in a 9 mol% yttria-stabilized zirconia matrix were synthesized by the coprecipitation route using a low-silica zirconium precursor. Characterization techniques included scanning electron microscopy, X-ray diffraction, Vickers hardness and impedance spectroscopy. As a consequence of optimization of the synthesis route a homogeneous dispersion of the additive along with good densification was obtained. Although alumina addition to stabilized zirconia exerts a deleterious effect on the electrical conductivity, it improves the Vickers hardness and fracture toughness of the composite materials.