High temperature oxidation resistance improvement of carbon-carbon composite

✍ Scribed by T. Li; Z. Yang; S. Qiao; X. Zheng

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 245 KB
• Volume: 31
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(93)90102-g

✦ Synopsis

Letters to the Editor 1361 structure of ACF is very sensitive to the surrounding atmosphere according to our preceding examination [4-61. The in situ X-ray diffraction can provide real structures of activated carbons in vacua. This work tried to determine the correct structural changes of ACF with high temperature treatment. Fig. 2 shows the growth of the graphitic crystahites during heat-treatment. Although these were the arbitrary rates we selected (after 1 hour) to express the growth rates of the crystallites, these data may be analyzed by an Arrhenius plot of the kinetics, as shown in Fig. 3. Both Arrhenius plots for the L, and L, changes bend upwards above 2073K. The Arrhenius plot for the higher temperature region should be associated with the growth of the micrographites for each direction.

The activation energies of stacking and widening of the micrographites are 114 and 57kJ molt, respectively.

The activation energy for the stacking of micrographites is twice as great as that for the widening.

1

We have shown that the computer-aided analysis of X-ray diffraction in vacua for activated carbon structures is now a possibility. In future the comparison of this approach with Raman spectroscopy will be important for the determination of the structure of lessgraphitized carbons.