MECHANICAL-PROPERTIES OF C/SIC COMPOSITES AS EXPLAINED FROM THEIR INTERFACIAL FEATURES

Carbon fibre reinforced ceramic matrix composites with pyrolytic carbon interphases prepared following various conditions are compared, together with interphase-free composites. Four composite grades are thus defined, considering similarities in the ultimate tensile strength and strain values. Textural then structural investigations of the interfacial zones are performed from a centimetric to nanometric scale in an attempt to explain the specific mechanical features of the composites for each grade. Results show that the carbon interphase texture obviously controls the macroscopic behavior of the composites. Composite toughnesses are directly related to the relative strengths of the various interfaces, which depend on the covalent/Van der Waals bond ratio.