Disclinations in Carbon-Carbon Composites.
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 this 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. For arrays of disclinations in the carbonaceous mesophase, neighboring disclinations are of opposite sign and the total strength of an array tends to zero, as shown with the use of optical micrography. The strength S of a disclination is a measure of the amount of rotational distortion (2 Pi S) associated with each disclination. Crack propagation in the carbonaceous mesophase has been studied with the use of optical micrography and a wedge-opening specimen to produce incremental crack growth. The disclinations were shown to control the crack path, and to stop and divert the crack path. This evidence indicates that the disclinations in the carbonaceous mesophase contribute to the high work of fracture of graphitic materials by crack blunting, crack diverting and energy absorption.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1982
- Accession Number
- ADA121319
Entities
People
- J. E. Zimmer
- R. L. Weitz