Fabrication and Mechanical Properties of C/C-SiC-ZrC Composites

ZrC nano-particles with varied mass fractions were introduced into the CFRP (carbon fiber-reinforced plastics) green body by a slurry infiltration technique. After the pyrolysis of CFRP green body, the C/C-ZrC preform with different microstructure features were obtained. By infiltrating the liquid silicon into the C/C-ZrC preform, the C/C-SiC-ZrC composites were fabricated. The morphologies of C/C-ZrC preform and C/C-SiC-ZrC were observed by scanning electron microscopy (SEM). The porosity was measured by the Archimedes method. The flexural strength and fracture toughness were evaluated by three point bending and single edge notched-beam (SENB) tests, respectively. The morphologies of C/C-ZrC preform show that the ZrC nano-particles distribute homogeneously in the fiber bundle area and have an obvious influence on the microstructure. The measurement of mechanical properties indicates that the C/C-SiC-ZrC composites with a mass fraction of 5% nano-particles present the highest value in the flexural strength and fractural toughness. While the mass fraction of nano-particles exceeds 5%, both the flexural strength and fracture toughness of composites decrease. Combining the mechanical properties with the microstructure analysis, the high mechanical properties could be attributed to the more homogeneous distribution of SiC phase and the moderate fiber/matrix interfacial bonding strength.