Influence of Redox Cycling on the Physicomechanical Properties of Ceramics of the ZrO2 –Y2O3 –CeO2 –Al2O3 –NiO–CuO System

We study the influence of one-time reduction and redox cycling at 600°С in different hydrogencontaining media in the absence and in the presence of carbon dioxide on the strength and electric conductivity of ceramics of the ZrO2 –Y2O3 –CeO2–Al2O3–NiO–CuO system with lowered Y2O3 content and various ratios of the amounts of the ceramic and metallic phases. It is shown that cermets with different mass fractions of the nickel phase after reduction in pure hydrogen have high electric conductivity, which meets the requirements imposed on the anode materials. However, even in the absence of bulk microcracking, their strength after reduction becomes twice lower. The investigated ceramics in the initial state and cermets subjected to reduction at 600°С in different working media are characterized by the quasibrittle micromechanism of fracture. The redox treatment of cermets causes an insignificant increase in their electric conductivity but guarantees the level of strength close to the strength of the original ceramics, i.e., proves to be an efficient technology for improving the physicomechanical properties of Ni-containing anodes of solid-oxide fuel cells, including the case where CO2 impurities are present in the working medium.