New types of zirconia/nickel and carbon/nickel composites are being developed by using sol-gel processes. These offer the opportunity to create nano-sized and well distributed nickel particles embedded in the inorganic functional matrices. The desired amount, size and distribution of the metal particles can be controlled by the reaction parameters, also offering the possibility to grade and functionalize the materials. The mechanical properties (strength, fatigue, also under elevated temperatures) as well as the conductive properties (conductivity, polarization and charge transfer) are being investigated. The results of the single investigations will give a feedback to the material developer. At the same time the interface characteristics are being investigated in order to support the results of mechanical and conductive testing.
Nanostructured metal/ceramic composites in the systems c-ZrO2/Ni and c-ZrO2/N1/W have been developed but the application research is still underway. The achieveable metal load in the zirconia matrix is decisive for the application case. Resulting metal particle size is a function of the chelating agent, the degree of complexation and the final thermal treatment. Powder preparation was scaled up to 3.5 kg per attempt without any adverse effect on the final product. Stable sols consisting of nickel and zirconia precursors are useful for depositing thin films. Microstructure of Ni/c-ZrO2 and the mechanical properties are a function of composition and preparation parameters. Nanostructured dense Ni/c-ZrO2 is made electronically conductive by exceeding the percolation limit.