Processing and properties of nanostructured Ni-ZrO2 functional cermets

Nanostructured metal - ceramic powders in the system NI -Y2O3/ZrO2 with 5-80 vol.-% of the metallic phase were produced by wet - chemical methods. These powders with a primary metal crystallite size of 10-20 nm were fully densified by uniaxial hot pressing at 880-1000 deg C using pressures of 30-60 MPa. The microstructure development during sintering was mainly gowernded by the interfacial energies between the nickel- and the ZrO2 - grains. Depending on the composition and the microstructure a bending strength up to 490 MPa and a fracture toughness up to 6.8 MPa*m 1/2 were reached. Furthermore, the enhanced diffusivity and sinterability of nanostructured powders could be used profitably to join Cr - steel- and YSZ - plates by means of Ni-ZrO2 interlays.