Study on toughening mechanisms of pyrolytic carbon interface layer in C_f/ZrB₂-SiC composites using in-situ tensile experimental and numerical methods

The toughening mechanism in continuous fiber toughened ZrB₂-SiC ceramic matrix (C_f/ZrB₂-SiC) composites was studied upon introduction of pyrolytic carbon coating at the fiber/matrix interface. The real-time deformation behavior, surface crack initiation and evolution of C_f/ZrB₂-SiC composites under tensile load were studied using in-situ scanning electron microscopy (SEM) to determine the typical damage modes and toughening mechanisms. A refined microscopic representative volume element (RVE) inserting the cohesive zone elements was established to study the PyC interface layer damage by using finite element method. It was found that PyC interface layer damage induced by thermal residual stress (TRS) was one of critical factors affecting the mechanical performance of the C_f/ZrB₂-SiC composites. The critical thickness of the interface layer was also further determined by analyzing the effect of interface layer thickness on the distribution of TRS, which can guide the design of PyC interface layer for manufacturing the C_f/ZrB₂-SiC composites.