THE VAPORIZATION OF PYROLYTIC GRAPHITE
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GENERAL ELECTRIC CO PHILADELPHIA PA MISSILE AND SPACE DIV
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The vaporization of pyrolytic graphite was studied by the Knudsen effusion and Langmuir free vaporization techniques using a microbalance and a time-of-flight mass spectrometer. Vapor pressures were obtained in the temperature range 2417K - 2700K for C, C sub 2, and C sub 3 respective heats of vaporization were calculated by the third-law method. Langmuir vaporization measurements were carried out in the temperature range 2250K - 2760K. The ratios of vaporization coefficients obtained from mass spectroscopic measurements are alpha sub 2alpha sub 1 2.1, alpha sub 1alpha sub 3 10.6. Use of vapor pressure data and vaporization rates was made to arrive at an overall vaporization coefficient equal to 0.095 and individual values of alpha sub 1 0.24, alpha sub 2 0.50 and alpha sub 3 0.023.
- Ceramics, Refractories and Glass