The microstructure, electrical resistivity, and thermal diffusivity of
nickel-zirconia cermets have been studied. Scanning electron microsco
py of the fracture surfaces of samples shows that there are some small
isolated nickel granules adhering to the surface of the zirconia part
icles. Considering such a microstructural feature of samples and the l
aw of mixtures, an improved model for electrical and thermal conductiv
ity is established. With this model, the experimental results-that ele
ctrical conductivity and thermal diffusivity increase with increasing
nickel content-are interpreted. Moreover, the thermal diffusivity is o
bserved to be almost linearly related to temperature.