High cross-linked carbon Nanotube/Polycarbosilane precursor for deriving SiC ceramics with improved thermal diffusion and mechanical properties

Abstract

Based on a multi-walled carbon nanotube/polycarbosilane (MWCNT/PCS) hybrid precursor with a highly cross-linked structure, MWCNT/silicon carbide (SiC) ceramic monoliths were prepared via hot-press sintering at 1900 ℃ and 30 MPa. Owing to the precursor structure, with its high cross-linking density and chemically bonded MWCNT, the relative and absolute densities of the SiC ceramics were enhanced. We also examined the composition, microstructure, mechanical performance, and thermal properties of the monoliths. The results indicated that the introduction of 1 wt% MWCNTs to the precursor increased the Vickers hardness by 58 %, fracture toughness by 70.8 %, and thermal diffusivity coefficient by 55.5 %. A higher density of MWCNT/SiC ceramic monoliths was crucial for improving the mechanical performance and influencing the thermal diffusivity coefficient. This study provides a new approach for improving the fracture toughness and strength of SiC ceramics and expands the application prospects of composite ceramics under thermal conditions.