Role of fiber–matrix adhesion at CFRP stage on microstructure and mechanical properties of C/C–SiC composite

Abstract In order to understand the role of fiber–matrix adhesion (FMA) at carbon fiber‐reinforced polymer (CFRP) stage on the microstructure and mechanical properties of C/C–SiC composite via liquid silicon infiltration (LSI) process, the FMA was adjusted by thermal treatment of carbon fibers at different temperatures and evaluated by means of single fiber push‐out technique. The microstructure was characterized by optical microscopy and scanning electron microscopy. The mechanical properties were measured by the double‐notched shear test, three‐point flexural test, and single edge‐notched beam test, respectively. Results indicated that the microstructure and mechanical properties of C/C–SiC composite via LSI were closely associated with the FMA at CFRP stage. The microstructure of C/C–SiC composite fabricated by using the CFRP with high FMA presented nonhomogeneous distribution and concentration of SiC matrix. In contrast, the C/C–SiC composite fabricated by using the CFRP with low FMA, the high content of SiC distributed homogeneously and surrounded the fiber, which resulted in a strong bonded C–SiC interface. The strong C–SiC interface is detrimental to the fracture toughness, but it is beneficial to the improvement of oxidation resistance. To obtain desired mechanical properties of C/C–SiC composite, the control of interface bonding is important, which can be realized by modifying the FMA at CFRP stage.