Thermal and Mechanical Properties of ZrB₂-SiC Ceramics Fabricated by Hot Pressing with Change in Ratio of Submicron to Nano Size of SiC

Abstract

ZrB 2 -SiC ceramics are fabricated via hot pressing with different ratios of submicron or nano-sized SiC in a ZrB 2 -20 vol%SiC system, in order to examine the effect of the SiC size ratio on the microstructures and physical properties, such as thermal conductivity, hardness, and flexural strength, of ZrB 2 -SiC ceramics. Five different ZrB 2 -SiC ceramics (ZrB 2 -20 vol%[(1-x)SiC + xnanoSiC] where x = 0.0, 0.2, 0.5, 0.8, 1.0) are prepared in this study. The mean SiC particle sizes in the sintered bodies are highly dependent on the ratio of nano-sized SiC. The thermal conductivities of the ZrB 2 -SiC ceramics increase with the ratio of nano-sized SiC, which is consistent with the percolation behavior. In addition, the ZrB 2 -SiC ceramics with smaller mean SiC particle sizes exhibit enhanced mechanical properties, such as hardness and flexural strength, which can be explained using the Hall-Petch relation.