Preparation and Properties of C/SiC Composites via Liquid Silicon Infiltration Process

Abstract

Three-dimensional short carbon fiber felt reinforced C/SiC composites were prepared by the liquid silicon infiltration (LSI) process. The influences of different porosity ratios, carbon coating, and heat treatment of C/C substrates, on the properties of C/SiC composites were studied. The optimized porosity ratio is calculated as 40.1% when the volume percent of carbon fiber (including carbon coating) is 23%, and after screening porosity ratio from ~55% to ~20%, the optimized experimental result (39.5%) is highly in accordance with the design value. The C/SiC composite after process parameter optimization, has a flexural strength and modulus of 125 MPa and 120 GPa, respectively. The C/SiC composite without carbon coating has a flexural strength of only 77 MPa, showing carbon coating plays a key role. The heat treatment of C/C substrate at 1600°C also improves the flexural strength of C/SiC composite for nearly 50%, and porosity rearrangement and interface weakening are believed to contribute such improvement.