Failure behavior of interfacial domain in SiC-matrix based composites

In this work, the microstructure, failure behavior and interfacial properties with respective to the interfacial domain in SiCf/BN/SiC and Cf/PyC/SiC composites were studied via the fiber push-in test. The differences in the mechanical response of the interfacial domain were observed. During the fiber push-in test for SiCf/BN/SiC, the interface debonding accompanied with interphase fracture occurred, resulting in an obvious sign of the onset of debonding on loading-displacement (P-u) curves. While the good continuity of P-u curves can be observed for Cf/PyC/SiC, which is due to that the failure is in the form of interface debonding along with interphase lateral slipping caused by the extension of buckled carbon fiber, without any interphase fracture. The interfacial properties calculated from the fiber push-in test show that Cf/PyC/SiC possesses a weaker interfacial domain compared with SiCf/BN/SiC. The interfacial shear stress of SiCf/BN/SiC and Cf/PyC/SiC composites amounts 94.2 and 48.1 MPa, respectively.