Accession Number : ADA135248

Title :   Disclinations in Carbon-Carbon Composites.

Descriptive Note : Annual rept. no. 2, Jul 82-Jul 83,


Personal Author(s) : Zimmer,J E ; Weitz,R L

PDF Url : ADA135248

Report Date : Sep 1983

Pagination or Media Count : 83

Abstract : 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.

Descriptors :   *Carbon carbon composites, *Liquid crystals, *Mechanical properties, Microstructure, Cores, Matrix materials, Fracture(Mechanics), Structural analysis, Crack propagation, Fiber reinforced composites

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE