Structure - Property Relationships of Ni/YSZ and Ni/(YSZ+TiO2) Cermets

Cermets composed of nickel metal and Y2O3-ZrO2-TiO2 ternary ceramics were investigated by X-ray diffraction, dilatometry, electrical and microstructural measurements and are regarded as improved anode materials with respect to long-term stability. With increasing titania content it was possible to minimise the electrical and microstructural changes during long-term annealing at 1000 °C in reducing atmosphere. Under these conditions a cermet containing a ceramic with 10 mol% TiO2 showed a reduction in electrical conductivity of only 8% after 1000 h and a change in Ni particle size from only 1.6 to 1.8 μm. The results are explained in terms of an improved bonding strength at the interface between the ceramics and the metal due to a reduction of interfacial energy and are compared with results obtained with SOFC anode substrate materials.