Understanding the creep behavior of a 2.5D Cf–SiC composite-I. Morphology and microstructure of the as-received material

A carbon fiber-reinforced silicon carbide matrix composite (2.5D Cf–SiC composite) is characterized from both a morphological and a microstructural point of view, as a prerequisite to an investigation of its creep behavior. Using automatic image analysis, various morphological parameters have been characterized: the texture of the woven fibrous preform, the fiber size distribution and the volume fraction of macropores. An original study of the pre-existing microcracks has also been conducted to enable a quantitative estimate of the damage in the as-received composite to be made. A microstructural investigation down to the nanometric scale, via transmission and high resolution electron microscopies, has revealed the intimate structure of each constituent. Thus, the classical structural elements of the carbon fibers (i.e. basic structural units and areas of local molecular orientation) have been identified and measured. The texture of the pyrocarbon interphase has been clearly established especially at the fiber/pyrocarbon and pyrocarbon/matrix interfaces. Finally, the matrix presents the common features of chemically vapor deposited matrices.