Microstructural Evolution and Mechanical Behaviors of Cf/Cm-SiC-(ZrxHf1−x)C Composites with Different Carbon Matrices

In this study, two types of porous Cf/Cm composites were obtained by introducing pyrolytic carbon (PyC) and pyrolytic carbon/furan resin carbon (PyC/FRC). Subsequently, Cf/Cm-SiC-(ZrxHf1−x)C composites with different carbon matrices were prepared by introducing SiC and (ZrxHf1−x)C matrices into the porous Cf/Cm composites via the reactive melt infiltration method, specifically termed as Cf/PyC-SiC-(ZrxHf1−x)C and Cf/PyC/FRC-SiC-(ZrxHf1−x)C composites. The microstructures of the porous Cf/Cm and Cf/Cm-SiC-(ZrxHf1−x)C composites with different carbon matrices were examined, and a comprehensive analysis was conducted on microstructural evolution and mechanical behaviors of the Cf/Cm-SiC-(ZrxHf1−x)C composites. The results indicate that both Cf/Cm-SiC-(ZrxHf1−x)C composites underwent similar microstructural evolution processes, differing only in terms of evolution kinetics and final microstructure. Differences in the pore structures of porous Cf/Cm composites, as well as in the reactivities of carbon matrices, were identified as primary influencing factors. Additionally, both Cf/Cm-SiC-(ZrxHf1−x)C composites exhibited “pseudo-ductile” fracture characteristics, with flexural strengths of 214.1 ± 8.8 MPa and 149.6 ± 12.2 MPa, respectively. In the Cf/PyC-SiC-(ZrxHf1−x)C composite, crack initiation during loading primarily originated from the ceramic matrix, while in the Cf/PyC/FRC-SiC-(ZrxHf1−x)C composite, failure initially arose from the residual FRC matrix. Excessive fiber corrosion and the presence of residual low-modulus FRC matrix resulted in lower mechanical performance.