Polymer precursor-derived HfC-SiC ultrahigh-temperature ceramic nanocomposites

Due to poor mechanical properties and antioxidation properties, etc of single phase ultrahigh-temperature ceramics (UHTCs), the second phase such as SiC was usually introduced for improving those properties. Herein, a novel stratagem for synthesis of binary HfC-SiC ceramics has been presented. A Hf-O-Hf polymer as a HfO2 precursor has been synthesized for preparing soluble HfC-SiC precursors with high solid content and low viscosity solutions without additional organic solvents. The structure of PHO was characterized by FTIR and H-1-NMR, the crystalline behavior and morphologies of polymer-derived ceramics were identified by XRD, SEM-EDS, and TEM. It was shown that PHO firstly transformed into HfO2, and then reacted with in situ carbon derived from DVB and PCS thus producing cubic HfC through carbothermal reduction. In addition, the obtained HfC-SiC nanopowders exhibited spherical morphology with a diameter less than 100 nm, while the Hf, Si, and C are homogeneously distributed.