Mechanical properties and electromagnetic shielding performance of single-source-precursor synthesized dense monolithic SiC/HfC_{: X}N_{1- x}/C ceramic nanocomposites

For the first time, single-source-precursor synthesized dense monolithic SiC/HfC_xN_1-x/C ceramic nanocomposites with outstanding electromagnetic (EM) shielding performance at temperatures up to 600 °C are reported. The total shielding effectiveness (SE_T) of the SiC/HfC_xN_1-x/C monolith is >40 dB at 600 °C, which is superior than most of the reported EM shielding materials under the same conditions. Compared with a Hf-free SiC/C monolith, the SiC/HfC_xN_1-x/C monolith possesses superior EM shielding performance due to the presence of a highly conductive HfC_xN_1-x phase. Moreover, the HfC_xN_1-x-particles are covered by a carbon layer forming core-shell nanoparticles connected with graphite-like carbon ribbons, which result in electrically conductive networks within the semiconducting β-SiC matrix. In addition, the hardness, Young's modulus and flexural strength of the dense SiC/HfC_xN_1-x/C monolith are measured to be 29 ± 4 GPa, 381 ± 29 GPa and 320 ± 25 MPa, respectively. The outstanding EM shielding performance combined with excellent mechanical properties of the dense monolithic SiC/HfC_xN_1-x/C nanocomposites provides a novel strategy to fabricate EM shielding materials for applications in harsh environments and/or under high mechanical load.