Infiltration Behavior and Pore Evolution of C f /SiC Composites Prepared by SI–RMI: Influence of Slurry Solid Loading

ABSTRACT C f /SiC composites were fabricated via a combined slurry impregnation and reactive melt infiltration (SI–RMI) route to reduce residual silicon and improve mechanical properties. The influence of slurry solid loading on pore structure evolution, infiltration behavior, and composite properties was systematically investigated. Slurry solid loading strongly affected rheological and sedimentation behaviors, thereby governing pore filling. The 20 vol.% slurry exhibited the most favorable infiltration behavior, producing a refined pore structure (423.6 µm), whereas the 40 vol.% slurry caused heterogeneous infiltration and pore coarsening (1194.0 µm) because of its high viscosity and filtration/bridging effects. The synergistic effect of slurry impregnation and compound carbon design established a volumetrically distributed reactive carbon network within the pore space and promoted balanced infiltration–reaction coupling, enabling continuous silicon consumption and suppressing silicon accumulation. Consequently, the 20 vol.% sample achieved the lowest residual Si content (1.2 vol.%), the highest bulk density (2.44 g·cm −3 ), and the highest flexural strength (349.3 MPa).