Effect of cyclic loading on interfacial shear stress in SiC-CAS glass ceramic matrix composite

Mechanical fatigue has been observed to occur in the Nicalon-CAS continuous fibre reinforced glass ceramic matrix composite under cyclic loading at room temperature, and both microcrack proliferation and propagation are induced. In situ fibre push down tests within a scanning electron microscope have then been used to assess changes in interfacial properties as a result of this mechanical cyclic loading. Both the interfacial shear stress and the interfacial fracture energy decrease when specimens are subjected to mechanical cyclic loading. It is deduced that a decrease in interfacial shear stress is the most likely mechanism driving stable and progressive microcrack propagation. (C) 1998 The Institute of Materials. (C) 1998 The Institute of Materials