Carbon Vaporization/Condensation Effects
Final rept. Jun 1979-Sep 1983
AEROSPACE CORP EL SEGUNDO CA AEROPHYSICS LAB
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The energy dissipating efficiency of carbon materials were studied. Equilibrium thermochemical properties and kinetic vaporization rate information have been obtained for temperatures approaching 4500 deg K. A nonequilibrium ablation model and carbon laser vaporization experiments were used to determine the total vapor pressure, melt temperature limits, and the temperature dependence of carbon vaporization rate coefficients for different types of graphite. In addition, rough surface emissivities for these graphites were measured, and a preliminary study of the effects of carbon particles on infrared radiation transport in a laser-vaporized carbon plume was carried out. This information makes possible the reliable prediction of the performance of the carbon material thermal protection systems in extreme heat transfer environments. The measured vapor pressures are two to three times higher than those given by the current JANAF tables, and the melt temperature limits are 300 to 600 deg K higher than current literature values. To our knowledge, our data represent the first reported temperature dependence of carbon vaporization coefficients.
- Radiation and Nuclear Chemistry
- Atomic and Molecular Physics and Spectroscopy