HIGH-TEMPERATURE MASS SPECTROMETRY. VOLUME 1. FREE VAPORIZATION STUDIES OF GRAPHITES
AEROSPACE CORP EL SEGUNDO CA LAB OPERATIONS
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Some of the differences in the published data on the free vaporization of conventional ATJ, ZTA, UT-6 and pyrolytic graphites were resolved. Relative abundances, relative rates of vaporization, and activation energies of vaporization have been measured for carbon species C1 through C5, for conventional graphites in the temperature range 2800 - 3000K, and for pyrolytic graphite in the temperature range 2600 - 3000K. Differences in the free evaporation behavior of the two types of graphites are discussed. Plausible vaporization mechanisms are presented that account for the time dependency of species distribution at constant surface temperature for conventional graphites, and for the differences in activation energies of vaporization for C4 and C5 molecules vaporizing from pyrolytic and conventional graphites. The effects of the differential rates of carbon evaporation from the crystalline and binder phases on the free vaporization behavior of conventional graphites at temperatures greater than about 2950K are described.
- Ceramics, Refractories and Glass
- Atomic and Molecular Physics and Spectroscopy