Carbon nanostructure-reinforced SiC/SiN composite with enhanced thermal conductivity and mechanical properties.

Carbon nanostructures (CNS) as a kind of reinforcement material can remarkably enhance the mechanical and thermal properties of ceramics. This research presents an analysis of the influence of CNS on the thermal conductivity and mechanical properties of SiC/SiN composites. The SiC/SiN composites containing various types of CNS carbon nanofibers (CNF), multi-walled carbon nanotubes (MWCNT) and graphene nano-platelets (GNP) were fabricated by hot-press sintering. XRD analysis confirmed a complete transformation of α-SiN to β-SiN and microstructural analysis shows a uniform distribution, as well as a pullout and bridging mechanism of CNS. The results revealed that the thermal conductivity and mechanical properties of SiC/SiN composites increased with the addition of CNS. Maximum values of fracture toughness (9.70 ± 0.8 MPa m) and flexural strength (765 ± 58 MPa) have been achieved for the MWCNT-containing SiC/SiN composite, whereas the maximum values of Young's modulus (250 ± 3.8 GPa) and hardness (27.2 ± 0.9 GPa) have been achieved for the CNF-containing SiC/SiN composite. Moreover, thermal conductivity also improved with the addition of CNS and reached a maximum value of 110.6 W m K for the CNF-containing SiC/SiN composite. This work provides a useful approach for the fabrication of high-performance multifunctional composites for emerging engineering applications.