Preparation of 3D-Cf/SiC composites at low temperatures

The conversion process of the polycarbosilane (PCS) into silicon carbide (SiC) was investigated by TG–DTA, IR, XRD, etc., which indicated the feasibility of transition from PCS to SiC ceramics at low temperatures under 1000 °C. The results show that the inorganic transition of PCS appears at about 750 °C, and the crystal emerges at 880 °C approximately. The carbon fiber reinforced silicon carbide composites (Cf/SiC) were hereby prepared at low temperatures as 700 °C, 800 °C, 900 °C, 1000 °C, respectively through precursor infiltration and pyrolysis (PIP). The mechanical properties of Cf/SiC composites prepared at low temperatures were almost all outstanding, with the flexural strength of 600.3 MPa for Cf/SiC composites prepared at 1000 °C, the shear strength of 64.2 MPa and the fracture toughness of 22.5 MPa m1/2. And the flexural strength of composites at 1600 °C in vacuum was 411.2 MPa, which was prepared at 900 °C, while the flexural strength at room temperatures was 527.4 MPa.