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

Carbon fibre reinforced ceramic matrix composites with pyrolytic carbo n interphases prepared following various conditions are compared, toge ther with interphase-free composites. Four composite grades are thus d efined, considering similarities in the ultimate tensile strength and strain values. Textural then structural investigations of the interfac ial zones are performed from a centimetric to nanometric scale in an a ttempt to explain the specific mechanical features of the composites f or each grade. Results show that the carbon interphase texture obvious ly controls the macroscopic behavior of the composites. Composite toug hnesses are directly related to the relative strengths of the various interfaces, which depend on the covalent/Van der Waals bond ratio.