Disclinations in Carbon-Carbon Composites.
Annual rept. no. 2, Jul 82-Jul 83,
ACUREX CORP/AEROTHERM MOUNTAIN VIEW CA
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Disclinations are prominent in the matrix microstructure of carbon-carbon composites and are introduced via the formation of the carbonaceous mesophase, a discotic nematic liquid crystal. The structure-sensitive physical properties of these composites are expected to be related to their microstructure and the disclination structures in the microstructure. The objectives of this research are to identify and classify the disclination structures in the matrix of carbon-carbon composites and to determine the relationship of the disclinations to the fracture behavior of the composite matrix. The three-dimensional structure of disclination arrays in the carbonaceous mesophase has been delineated by optical micrography on successive parallel planes of section. The disclinations intersected each plane of section, denoting a line character to the central core of the disclinations. This analysis showed that the disclinations lines cores are generally curved and can interact by two disclinations joining to form a single disclination or by one disclination separating to form two disclinations. Disclination theory requires that for such disclination interactions, the total strength or rotation of the disclinations must be conserved. The evidence obtained in this study supports this requirement. This mapping of the three-dimensional structure of the disclination arrays provides a better insight into the complex microstructure of carbon-carbon composites.
- Laminates and Composite Materials