Carbon nanostructure-reinforced SiC_w/Si₃N₄ 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_w/Si₃N₄ composites. The SiC_w/Si₃N₄ composites containing various types of CNS e.g. 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-Si₃N₄ to β-Si₃N₄ 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_w/Si₃N₄ composites increased with the addition of CNS. Maximum values of fracture toughness (9.70 ± 0.8 MPa m^1/2) and flexural strength (765 ± 58 MPa) have been achieved for the MWCNT-containing SiC_w/Si₃N₄ 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_w/Si₃N₄ composite. Moreover, thermal conductivity also improved with the addition of CNS and reached a maximum value of 110.6 W m^-1 K^-1 for the CNF-containing SiC_w/Si₃N₄ composite. This work provides a useful approach for the fabrication of high-performance multifunctional composites for emerging engineering applications.