Disclination Structures in Carbon and Graphite.
AEROSPACE CORP EL SEGUNDO CA MATERIALS SCIENCES LAB
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Carbon materials are structurally unique, owing to their relationship to liquid crystals. Pyrolysis of precursors that pass through a liquid crystalline mesophase state is the process by which most carbons form. The lamelliform morphologies that are locked in as the carbonaceous mesophase hardens lack grain boundaries but possess disclinations as their most prominent structural feature. Practical materials, ranging in value from petroleum coke to mesophase carbon fiber, form while the mesophase undergoes deformation, and the disclinations can react extensively before they are entrapped by hardening. Thus, most carbons and graphites may be regarded as mesophase fossils with disclination-dominated microstructures that vary with the nature and extent of deformation and with the time allowed for the disclinations to react and relax before hardening. Keywords Mesophase, Disclination, Liquid crystal, Coke, Graphite, Pitch, Carbon fiber, Carbonization, Pyrolysis, Oxidation, Stabilization.
- Refractory Fibers