Thermal conductivity of SiC ceramic fabricated by liquid infiltrating molten Si into mesocarbon microbeads-based preform

The thermal conductivity of SiC ceramics fabricated by liquid infiltrating molten Si into mesocarbon microbeads-based preform was investigated. The thermal conductivity of SiC ceramics decreased from 103 to 36 W·m− 1·K− 1 at room temperature when the volume fractions of SiC, residual Si and unreacted C varied from 76.7 to 51.2 vol.%, 11.2 to 0 vol.% and 10.0 to 45.3 vol.%, respectively. The microstructural investigation and Maxwell's model analysis revealed that the difference in thermal conductivity of the samples was mainly affected by the unreacted C and transition layer, which surrounding around the unreacted C, was composed of inhomogeneous and sparser SiC nanocrystalline. Since the volume of the transition layer was mainly determined by the outer area of the carbon particles, the unreacted C and transition layer, with relative low thermal conductivity, can make the thermal conductivity sharply decrease with the unreacted C content increasing.