Characterization of Graphitization in Coal Tar and Petroleum Pitches.
Abstract
This study investigated the effects of heat-treatment temperature and residence time on graphitization of coal-tar pitch and petroleum pitch used in carbon/carbon composites. Samples were heat-treated at various temperatures (550 C-2550 C) and two different residence times of 15 minutes and 30 minutes. They were examined using x-ray diffraction (XRD), scanning electron microscopy(SEM), laser Raman microprobe analysis (LRMA), and electron energy loss spectroscopy (EELS). In addition, a unidirectional carbon/carbon composite was examined using LRMA. A graphitization index was established using XRD, and degree of graphitization was determined using LRMA. All four techniques showed changes in the pitch materials as a result of processing parameters. With increasing heat-treatment temperature (HTT) XRD showed a decrease in d-spacing indicative of tighter planar packing, a narrowing of peak breadth indicative of an increase in crystalline size, and an increase in peak intensity. This corresponds to an increase in degree of graphitization with increasing HTT. SEM showed establishment of morphologies representative of two- and then three-dimensional ordering in the pitch samples with increasing HRR indicating the progression of graphitization. LRMA showed an increase in the 1575/cm peak intensity and a narrowing of the peak while the 1355/cm peak decreased with increasing temperature and residence time, indicating increasing degree of graphitization. EELS showed a change in spectra from one characteristic of graphitized carbon as heat-treatment increased.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1985
- Accession Number
- ADA166942
Entities
People
- Janet C. Karika
Organizations
- Air Force Institute of Technology