Property tailorability for advanced CVI silicon carbide composites for fusion

Chemically vapor infiltrated (CVI) silicon carbide (SiQ matrix composites with uni-directional and various two- and three-dimensional reinforcements by the near-stoichiometric SiC fibers or SiC/graphite hybrid fabrics were produced and evaluated for tensile, thermal and electrical properties. The parallel-serial approach models of these properties reasonably explained the experimental results. The experimental data and the model-based analysis suggested that, for the composite systems studied: (1) the strength properties are determined primarily by the volume fraction of longitudinal fibers, approximately following the theory that assumes the global load sharing; (2) presence of the axial fiber tows is the key factor in providing high thermal conductivity; (3) the maximum and minimum post-irradiation through-thickness conductivity of 10-15 W/m K at 800-1000 degrees C for 3D architecture and < 5 W/m K at < 800 degrees C for 2D architecture, respectively, and (4) the orthogonal 3D configurations of x:y:z = 1:1:0.2 to 1:1:0.5 will provide the highest post-irradiation resistance to thermal stress due to a through-thickness heat flow. (c) 2005 Elsevier B.V. All rights reserved.