Effects of high-temperature annealing on the microstructures and mechanical properties of Cf/SiC composites using polycarbosilane

Three-dimensional carbon fiber reinforced silicon carbide (3D Cf/SiC) composites were fabricated by precursor infiltration and pyrolysis with polycarbosilane as the matrix precursor, and effects of high-temperature annealing on the microstructures and mechanical properties of the Cf/SiC composites were investigated. It was found that the high-temperature annealing had a great effect on the mechanical properties of Cf/SiC composites. When the annealing time was 1 h, the flexural strength of Cf/SiC composites gradually decreased with the elevation of annealing temperature, but the flexural modulus slightly changed within the range of 44.9–50.7 GPa; and the brittle fracture behavior was shown after 1700 °C annealing. When the annealing temperature was 1600 °C, the flexural strength of Cf/SiC composites decreased with the increasing annealing time, but the flexural modulus kept around 46 GPa; and the brittle fracture behavior appeared after 5 h annealing.