Influence of Texture and Thickness of Pyrocarbon Coatings as Interphase on the Mechanical Behavior of Specific 2.5D SiC/SiC Composites Reinforced with Hi-Nicalon S Fibers
Résumé
In the framework of nuclear applications of SiC/SiC composites, the influence of pyrocarbon interphase texture and thickness on the mechanical behavior both on as processed materials and on irradiated materials is a major concern. Thus, the PyC interphase influence has to be clearly addressed to define its optimal chemical vapor infiltration processing parameters. For this pur-pose, specific 2.5D SiC/SiC composites reinforced with Hi-Nicalon S fibers and with two kind of PyC texture and thickness were produced. Transmission electronic microscopy allowed PyC thickness and microstructure/texture characterizations, whereas push-out and tensile tests were employed as experimental mechanical procedures. Original result is that PyC nature directly in-fluences the Interfacial shear stress and failure mode of the weakest interface, regardless of PyC thickness. Adhesive failure or cohesive failure are highlighted depending on the PyC CVI deposition mechanisms. Similar post irradiation characterizations will be required to assess the role of irradiation on the PyC microstructure/texture evolution and mechanical behaviors of these materials.
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