Nanoscale characterization of interfacial mechanical properties in SiC/SiC composites fabricated by CVI + PIP method

The application of SiC/SiC composites is crucial for increasing the service temperature of aero-engine turbines. Among all densification processes for SiC/SiC composites, the chemical vapor infiltration (CVI) + polymer infiltration and pyrolysis (PIP) hybrid process combines the advantages of low porosity and high efficiency, making it one of the primary manufacturing processes for such materials today. In order to investigate the nanoscale mechanical properties of the SiC/PyC interface in SiC/SiC composites fabricated by CVI + PIP hybrid process, atomic-scale molecular dynamics simulations are performed based on high-resolution transmission electron microscopy observations and energy dispersive spectrometer analysis. Then, the corresponding cohesive zone model is developed to describe the damage law of the interface based on the obtained traction separation law. Finally, the interfacial shear strength (IFSS) is acquired based on the fiber pull-out simulation at the microscale, the effects of oxidation and residual stress on the interfacial fracture energy, cohesive strength and IFSS are discussed. This work provides a detailed analysis of the damage mechanism at the SiC/PyC interface in SiC/SiC composites from the nanoscale, which supports its application toward a better functional design.