Enhancing mechanical properties of heat-treated C/C composites via a simple additional ICVI treatment: Structural and performance optimization

Although high-temperature heat treatment improves the thermal stability and ablation resistance of carbon/carbon (C/C) composites, the generation of microcracks and the weakening of interfacial bonding strength severely reduce their mechanical properties. Herein, this work proposes a novel approach involving additional Isothermal Chemical Vapor Infiltration (ICVI) for heat-treated C/C composites (HT-C/C) to form re-carburizing composites (rHT-C/C), repairing defects generated during the heat treatment process and enhancing interfacial bonding. After additional ICVI, the flexural strength and interlaminar shear strength of rHT-C/C reaches 223.7 MPa and 14.9 MPa, respectively, representing increases of 45.8 % and 106.9 % compared to HT-C/C. The superior mechanical properties of rHT-C/C can be attributed to enhanced interface bonding combined with stepped crack propagation and a complex multi-directional crack network. This work provides a theoretical foundation and process optimization strategy for enhancing the mechanical performance of C/C composites, facilitating their application as high-temperature structural components.