Cellular Nickel-Yttria/Zirconia (Ni-YSZ) Cermet Foams: Manufacturing, Microstructure and Properties

Open-celled ceramic composite foams were prepared from NiO and yttria-stabilized zirconia (YSZ) powders by the polymer sponge replication (Schwartzwalder) technique using the respective aqueous dispersions. Mechanically stable NiO-YSZ foams with an average porosity of 93 vol.% were obtained. After chemical reduction of the NiO phase with hydrogen, cellular Ni-YSZ cermet structures were obtained. They are characterized by an electric conductivity up to 19∙10³ S∙m^-1 which can be adjusted by both, the Ni volume fraction, and the sintering/reduction procedure. The NiO-YSZ ceramic foams, as well as the cellular Ni-YSZ cermets prepared therefrom, were characterized with respect to their microstructure by scanning electron microscopy, confocal Raman microscopy and X-ray diffraction with Rietveld analysis. In addition, the compressive strength, the electric conductivity and the thermal conductivity were determined. The collected data were then correlated to the sample microstructure and porosity and were also applied for modelling of the mechanical and electric properties of the bulk Ni-YSZ strut material.