Effect of SiC content on the mechanical behaviour of a three-dimensional needled C/SiC composite

In this study, the effect of the silicon carbide (SiC) matrix content on the mechanical behaviour of a three-dimensional needled carbon fibre-reinforced SiC matrix composite (C/SiC) was investigated. The SiC matrix content was controlled by the infiltration time, and it can be divided into two stages for the evolution of matrix densification, leading to different mechanical responses. In the first stage, with an increase in the SiC matrix content from 12 to 39 vol%, the matrix was filled into a non-woven cloth, leading to an improvement in the loading efficiency of the fibre bundles. Thus, flexural strength and fracture toughness increased sharply from 54 to 218 MPa and 1.3–13.0 MPa m^1/2, respectively. As the SiC matrix content increases to 59 vol% in the second stage, the flexural strength and fracture toughness increased to 256 MPa and 15.4 MPa m^1/2, respectively. The infiltration ability of the SiC matrix into the non-woven cloth reached the threshold in this stage, and the SiC matrix filled the short-cut web layer, resulting in a slightly increasing tendency of strength and toughness.