Optimizing reactive melt infiltration using compound carbon sources for SiC matrix with low-residual silicon content

Carbon fibers-reinforced silicon carbide matrix (C_f/SiC) composites are widely used in aerospace for their high strength, ablation resistance, and oxidation resistance; however, residual Si in the SiC matrix significantly affects their performance. This study explores reactive melt infiltration using compound carbon sources to improve carbon density in the green bodies, with the objective of optimizing the phase composition, microstructure, and properties of SiC matrix. Results demonstrate that increasing carbon density leads to significant reduction in residual Si content while improving density, mechanical strength, and thermal conductivity of the SiC matrix. At an optimal carbon density of 0.86 g·cm⁻³, the SiC matrix achieved a residual Si content of 13.3 vol%, bulk density of 3.05 g·cm⁻³, flexural strength of 348.0 MPa, hardness of 25.86 GPa, and room-temperature thermal conductivity of 101 W·(m·K)⁻¹. This research presents a simple and cost-effective approach for producing high-performance C_f/SiC composites.