EFFECT OF INTERFACIAL LAYER ON THE FRACTURE-BEHAVIOR OF THE SIC FIBERBOROSILICATE GLASS COMPOSITES

The effect of structure and chemistry of interphase on the fracture be haviour of the SiC fibre/pyrex composites has been examined using TEM and PEELS. For all Nicalon/pyrex samples investigated, interfacial lay ers of similar to 30-35 nm thickness were observed, regardless of vari ations in the interfacial stress and difference in fracture mode. The sample of Tyranno fibre-reinforced pyrex which fractured in a brittle manner, and showed extensive diffusion of matrix elements into the fib res had a much thicker interfacial layer of similar to 100 nn thicknes s. SAD pattern and PEELS data confirmed that the interfacial layer in Tyranno/pyrex was carbon-rich. This indicates that the presence of a c arbon-rich interfacial layer does not necessarily lead to damage-toler ant composites.