Improvement of the mechanical and thermophysical properties of C/SiC composites fabricated by liquid silicon infiltration

Two different matrices (silicon and Ti₃SiC₂) were introduced into two-dimensional woven C/SiC reinforced with T-300™ carbon fiber (40vol.%) by liquid silicon infiltration, and their mechanical and thermophysical properties were studied compared with those of C/SiC fabricated by chemical vapor infiltration. C/SiC-Si shows higher tensile strength than C/SiC and C/SiC-Ti₃SiC₂ due to the existence of low thermal residual stress (TRS), while the low interlaminar shear strength and three-point bending strength of C/SiC-Si can be attributed to the brittleness of dense Si-SiC matrix. The introduction of Ti₃SiC₂ in a dense matrix can cause toughening mechanisms and inhibit the crack propagation by various micro-deformations of Ti₃SiC₂ grains. Therefore, C/SiC-Ti₃SiC₂ shows higher Young's modulus, interlaminar shear strength and thermal conductivity than C/SiC and C/SiC-Si. The low tensile strength is due to the existence of high TRS in C/SiC-Ti₃SiC₂.