A diffusion–reaction-deformation cohesive interface for oxidization and self-healing of PyC/SiC interfacial coating

This paper presents a fully coupled thermodynamically consistent diffusion–reaction-deformation cohesive model for pyrolytic carbon (PyC)/SiC interfacial coating in fiber-reinforced composites. Arrhenius function is used to capture the chemical kinetics and the Kuhn-Tucker conditions is exploited to describe the damage evolution of interfacial coating. A strong connection between the diffusion–reaction process and interfacial mechanical deformation is established by the cohesive model, and the rules of the model parameters are discussed in detail. Implementation of the cohesive zone model is conducted in ABAQUS finite element software through the use of UEL subroutines. A mesh convergence for the model is tested and the model is validated by the comparison with the experimental results. A Representative Volume Element (RVE) model for fiber-reinforced composites at different temperatures, equipped with custom cohesive elements, is constructed to investigate the impact of PyC/SiC coating during oxidation. Two-step simulation is adopted to solve the chemo-mechanical behaviors of interfacial coating. The impact of the interfacial coating on stress transfer between the matrix and fibers is highlighted by numerical results that demonstrate an initial decline in mechanical properties followed by an upward trend with increasing temperature. The model also captures the coupling mechanisms between the diffusion–reaction process and the interfacial deformation in the interfacial coating. Theoretical insights for fiber-reinforced composites in chemical environments are provided, guiding the design of interfacial coatings for potential engineering applications.