Change in microstructures and physical properties of ZrB2–SiC ceramics hot-pressed with a variety of SiC sources

Abstract ZrB 2 –SiC ceramics were fabricated by hot pressing with a variety of SiC sources in order to examine the effect of the SiC size on the microstructures and physical properties, such as hardness and thermal conductivities, of ZrB 2 –SiC composite ceramics. Three different ZrB 2 –SiC ceramics, ZPS (ZrB 2 –20 vol% polycarbosilane), ZFS (ZrB 2 –20 vol% fine-grained SiC), and ZNS (ZrB 2 –20 vol% nano-sized SiC), were prepared for this study. PCS is effectively transformed into β-SiC after hot pressing. By using PCS as a precursor for SiC, ZrB 2 particles are surrounded by fine particles of SiC, which results in the grain-growth inhibition of ZrB 2 . The effects of the SiC size on the microstructures and the physical properties of ZrB 2 –SiC ceramics were also investigated. ZrB 2 –SiC ceramics were produced by using various SiC sources in order to investigate the grain-growth inhibition and the mechanical/thermal properties of ZrB 2 –SiC. The sizes of ZrB 2 or SiC particles in the sintered bodies highly depend on the initial size of SiC. ZrB 2 –SiC ceramics with smaller SiC show enhanced mechanical properties, consistently with the Hall–Petch relation. The thermal conductivities of ZrB 2 –SiC ceramics with nano-SiC or PCS-derived SiC are higher than that of ceramics with conventional SiC, which can be explained by the percolation theory.