Microstructure, properties and damage characteristics of designed PyC interphase in C_f/SiC mini-composites

Pyrolytic carbon (PyC) interphase plays a crucial role in improving the mechanical properties of fiber-reinforced ceramic-matrix composites (FRCMCs). In this paper, three groups of PyC interphase were prepared: the first group (G1) with a mid-high texture PyC (MT-HT-PyC) interphase, the second group (G2) with a low/high texture combination PyC (LT/HT-PyC), and the third group (G3) with a low texture PyC (LT-PyC). The microstructure, intrinsic properties and interfacial properties of these three groups PyC interphase were characterized by SEM, TEM, Raman spectroscopy, nanoindentation tests, and fiber push-in tests. The result showed the LT-PyC with more amorphous PyC lattice and lattice defects is able to reduce the indentation modulus and interfacial properties of PyC interphase. The uniaxial tensile tests revealed that the C_f/SiC mini-composites containing a LT-PyC interphase could significantly improve their tensile strength, exhibiting a 34 % enhancement in tensile strength compared to those counterparts without LT-PyC interphase. The experimental result of scanning ion beam etching (SIBN) also showed that the interfacial crack propagates primarily within the LT-PyC interphase, rather than along the interface between the fiber and the interphase.