Preparation of zirconium phosphate bonded silicon nitride porous ceramics with low thermal conductivity

ZrP2O7 bonded α-silicon nitride (α-Si3N4) porous ceramics were prepared via pressureless sintering. The effect of porosity on the bending strength and thermal conductivity of the obtained samples was investigated. The results show that the thermal conductivity of the porous ceramics is in the range of 0.4-1.9 W/(m·K) when the porosity changes from 20% to 43%. The thermal conductivity of the sample is 1.9 W/(m·K) and the mechanical property does not reduce when the porosity is 20%. Also, the calculated thermal conductivity is in reasonable agreement with the experimental results when the proportional coefficients of the effective medium theory model and the Maxwell-Eucken 2 model are 0.3 and 0.7, respectively. ©, 2015, Chinese Ceramic Society. All right reserved.