Co-authors​ :

 Yucong WEI (CHINA) 

Internal stress is usually generated during the preparation of the SiCf/SiC composites and is generally considered to be uncontrollable and detrimental to SiCf/SiC composite’s mechanical properties. However, in this study, internal stress is proposed for the first time as a tool to regulate the interfacial bonding properties of the SiCf/SiC composites. And the interfacial compressive stress was successfully controlled by hybrid CVI and PIP methods. The results of Raman analysis show that the interfacial compressive stress increases with the increase of the PIP-SiC content. The interfacial shear strength (τi) and interfacial dynamic friction strength (τf) was determined by micro-shear tests. Both τi and τf increase with the increase of interfacial compressive stress. With different interfacial bonding strength, the SiCf/SiC composites show different tensile behaviors. The tensile behavior is dominated by τi before matrix cracking and high τi leads to a high tensile modulus and proportional limit stress (PLS). And the tensile behavior is dominated by τf after matrix cracking and high τf leads to the disappearance of the second linear stage and low fracture strain. Finally, the SiCf/SiC composite achieve the superhigh PLS of 729.8±9.2 MPa and modulus of 288.0±7.9 GPa when the BN thickness is 100nm and the interfacial compressive stress is 1127.7 MPa. This strategy of interfacial stress engineering may provide a new and valuable design idea for improving the mechanical properties of the SiCf/SiC composite and other composites. This strategy is also of great significance for broadening the design criteria and enriching the preparation methods of high-performance composites.