Mechanical Properties and Failure Behavior of 3D-SiC_f/SiC Composites with Different Interphases

Continuous silicon carbide fiber-reinforced silicon carbide ceramic matrix composites (SiC_f/SiC) are promising as thermal structural materials. In this work, the microstructure and static mechanical properties of 3D-SiC_f/SiC with PyC, SiC, and PyC/SiC and without an interface prepared via polymer infiltration and pyrolysis (PIP) were investigated systematically in this paper. The results show that the microstructure and static mechanical properties of SiC_f/SiC with an interphase layer were superior to the composites without an interlayer, and the interface debondings are existing in the composite without an interphase, resulting in a weak interface bonding. When the interphase is introduced, the interfacial shear strength is improved, the crack can be deflected, and the fracture energy can be absorbed. Meanwhile, the shear strength of the composites with PyC and PyC/SiC interfaces was 118 MPa and 124 MPa, respectively, and showing little difference in bending properties. This indicates that the sublayer SiC of the PyC/SiC multilayer interface limits the binding state and the plastic deformation of PyC interphase, and it is helpful to improve the mechanical properties of SiC_f/SiC.