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<p>Ceramic matrix composites (CMCs) are recognized as critical materials for next-generation aerospace engine hot-section components due to their high strength, low density, and high-temperature resistance. However, these components are typically subjected to concurrent high-temperature and oxidizing environments during service, rendering them vulnerable to oxidation-induced degradation and mechanical failure, which imposes significant constraints on their operational performance under extreme conditions. In this study, an experimental methodology to evaluate the high-temperature mechanical behavior of a representative CMCs has been established, namely silicon carbide fiber-reinforced silicon carbide (SiC<sub>f</sub>/SiC). The tensile properties of both unidirectionally reinforced and quasi-isotropic SiC<sub>f</sub>/SiC composites were systematically investigated. Fractographic analyses and microstructural characterization were conducted to elucidate the failure morphologies and internal structural evolution. The results indicate that the unidirectionally fiber-reinforced SiC<sub>f</sub>/SiC composites exhibit an average elastic modulus of 137.76&#xa0;GPa and an average tensile strength of 196.17&#xa0;MPa. In contrast, the quasi-isotropic SiC<sub>f</sub>/SiC composites demonstrate an average elastic modulus of 117.55&#xa0;GPa and an average tensile strength of 89.81&#xa0;MPa. In the unidirectionally fiber-reinforced architecture, oxidative consumption of the interphase layer between the matrix and fibers results in a smooth fiber surface morphology and the formation of distinct interfacial gaps, thereby contributing to enhanced toughness. Furthermore, elevated temperatures induce the propagation and closure of preexisting microcracks within the SiC<sub>f</sub>/SiC composite. The coefficient of thermal expansion mismatch between the fibers and the matrix modifies the residual stress field upon heating, promoting the closure of certain microcracks while concurrently generating localized tensile stresses in other regions, which provides a driving force for crack propagation.</p>

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The investigation of mechanical behavior and failure mechanisms of SiCf/SiC composites on high-temperature oxidation

  • 期刊论文

  • 发表日期：

    2026年7月24日

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  • Guohan Lin,
  • Yuanwen Hao,
  • Feng Hu,
  • Zhuochen Sui,
  • Hua Jin

摘要

Ceramic matrix composites (CMCs) are recognized as critical materials for next-generation aerospace engine hot-section components due to their high strength, low density, and high-temperature resistance. However, these components are typically subjected to concurrent high-temperature and oxidizing environments during service, rendering them vulnerable to oxidation-induced degradation and mechanical failure, which imposes significant constraints on their operational performance under extreme conditions. In this study, an experimental methodology to evaluate the high-temperature mechanical behavior of a representative CMCs has been established, namely silicon carbide fiber-reinforced silicon carbide (SiCf/SiC). The tensile properties of both unidirectionally reinforced and quasi-isotropic SiCf/SiC composites were systematically investigated. Fractographic analyses and microstructural characterization were conducted to elucidate the failure morphologies and internal structural evolution. The results indicate that the unidirectionally fiber-reinforced SiCf/SiC composites exhibit an average elastic modulus of 137.76 GPa and an average tensile strength of 196.17 MPa. In contrast, the quasi-isotropic SiCf/SiC composites demonstrate an average elastic modulus of 117.55 GPa and an average tensile strength of 89.81 MPa. In the unidirectionally fiber-reinforced architecture, oxidative consumption of the interphase layer between the matrix and fibers results in a smooth fiber surface morphology and the formation of distinct interfacial gaps, thereby contributing to enhanced toughness. Furthermore, elevated temperatures induce the propagation and closure of preexisting microcracks within the SiCf/SiC composite. The coefficient of thermal expansion mismatch between the fibers and the matrix modifies the residual stress field upon heating, promoting the closure of certain microcracks while concurrently generating localized tensile stresses in other regions, which provides a driving force for crack propagation.