Investigation of electrical properties of pressureless sintered ZrB2-based ceramics

ZrB2-based ceramics with different microstructures were prepared through different processes. Electrical resistivity of all samples was measured under vacuum environment by four-probe method over temperature range from 50 to 1000 degrees C. It was found that electrical resistivity and internal interface electrical resistivity of all samples increased linearly with environmental temperature. All samples showed nearly equal values of alpha, which was calculated using the formula: rho(T-1) = rho(T-0) + alpha.rho(T-0)center dot(T-1-T-0). This might be due to the fact that ZrB2 acted as electrical conductive phase in all samples. The relationship between electrical properties and microstructure of ZrB2-based ceramics was investigated. Increase in volume fraction of insulating phase and increase in internal interface electrical resistance can both cause effective electrical resistivity of ZrB2-based ceramics to increase. Internal interface electrical resistance was influenced by oxide impurities on the surface of ZrB2 particles and average particle size of ZrB2 particles.