Mechanical behaviour and microstructure of Cf/ZrC, Cf/SiC and Cf/ZrC – SiC composites

Cf/ZrC, Cf/SiC and Cf/ZrC–SiC composites were successfully prepared by polymer infiltration and pyrolysis (PIP) using polycarbosilane and a liquid ZrC precursor. The densification process, mechanical properties and microstructures were studied in a view of comparison. After the same total 20 PIP cycles, the Cf/ZrC, Cf/SiC and Cf/ZrC–SiC composites had flexural strengths of 50.1±5.3, 285.7±22.6, 141.5±13.1 MPa respectively; elastic moduli of 7.8±0.9, 57.1±3.2 and 45.1±2.6 GPa respectively; and fracture toughness of 2.5±0.2, 10.4±0.9 and 10.9±1.1 MPa m1/2 respectively. With the introduction of high modulus SiC phase into the ZrC matrix, the densification and modulus of the matrix were improved; as a result, the Cf/ZrC–SiC composite showed higher mechanical properties compared to Cf/ZrC.