Interfacial zone in continuous fiber-reinforced ceramic composites

A special area with certain thickness located between matrices and fibers is defined as 'interfacial zone' in this paper, which consists of a bulk phase (often called as interphase) and two interfaces, that is, the interphase/matrix interface and the interphase/fibre interface. The interactions between interfacial zone and matrix cracks are studied by transmission electron microscopy (TEM). It is found in the 3D C/SiC continuous fiber-reinforced ceramic composites (CFCC) that three kinds of interactions, i.e., the single and multiple deflection of matrix cracks, the debond or second cracks induced by the stress concentration ahead of matrix cracks tip, and the microcrack bridging mechanism at the nanometric scale, are observed at various places within and around the interfacial zone due to the evolvement of crack deflection/penetration competition. The analysis shows that these behaviors and their places are determined both by the toughness of correlative interfaces or fracture in the interfacial zone. Besides, some models are proposed for these interactions.