PREPARATION OF 3D-Cf/SiC COMPOSITE WITH LOW-MOLECULAR POLYCARBOSILANE

3D-Cf/SiC composites were prepared with low-molecular polycarbosilane (PCS) using a precursor infiltration pyrolysis (PIP) process. The average molecular weight of active PCS is 400 (Mn). The ceramic yield is approximately 70%, and PCS was translated into β-SiC crystal at 1200°C. The samples of 3D-Cf/SiC composites were prepared at three different heating rates. Bending strengthes were respectively 745.2 MPa, 686.7 MPa, and 762.5 MPa. SEM photographs of sample fracture surfaces indicate that in the micro-structures there are long fibers pulled out, and the fracture toughness is high. The matrix is close-grained. The research indicates that 3D-Cf/SiC composites with low-molecular polycarbosilane have good mechanical performance, and the low-molecular PCS fits the preparation of 3D-Cf/SiC composites by PIP process.