Effect of Heat Treatment on Mechanical and Thermal Properties of SiC/SiC Composites With Three-Dimensional Carbon Network

Abstract

\n SiC/SiC composites with high thermal conductivity shows promising application in field of fusion reactors. In this work, CNTs papers were fabricated by a vacuum filtration strategy while using pitch-based carbon fibers to build a network structure into SiC/SiC composite (SiC-CNTs-C/SiC, SCCS). The thermal conductivity and related mechanical properties before and after heat treatment at different temperature were investigated. The bonding between CNTs paper layers and SiC matrix were mainly mechanical. Compared to the composite without transfer channels, the bending strength of SCCS (434.54MPa) increased by 19% due to the reinforcement of transfer channels from the network structure. However, the damage to SiC fibers resulting from high temperature treatment adversely affected the mechanical properties. The disorder degree of SiC matrix and SiC fibers decreased after heat treatment while mean free path of phonons increased, which are conducive to heat transfer. Contracted to room temperature, the measured thermal conductivity at 1600℃ was 53.83 W/(m·K) in vertical direction and 29.85 W/(m·K) in plane. In summary, heat treatment apparently enhanced thermal conductivity of SCCS composites while partly sacrificed the mechanical properties.