tagungsband - Deutsche Bunsengesellschaft für Physikalische ...

Sa 19. 5. 2007, 12.30–12.50 A
Kurzvortrag - Hauptthema 19
Numerical prediction and measurement of
2D density distribution of C/C composites
synthesized by chemical vapor infiltration
Aijun Li, Günter Schoch, and Olaf Deutschmann
Institut für Technische Chemie und Polymerchemie,
Universität Karlsruhe
2D transient simulations of chemical vapor infiltration
from methane to carbon/carbon composites
were performed as well as predictions of bulk density
distribution, taking into account the interaction
between mass transport, homogeneous and heterogeneous
reactions. Corresponding CVI experiments
of carbon fiber felts with an initial fiber volume fraction
of 7.1% were also carried out at a temperature
of 1100 ◦ C, a pressure of 20 kPa and an average residence
time of 0.1 second. Total densification time is
up to 120 hours and measurements were conducted
at densification time of 39h, 90h and 120h, respectively.
Local distribution of bulk density of the carbon
fiber felts was measured by an X-ray, the intensity
of which is weakening after passing through
the sample. Based on the Lambert-Beer law, the
extinction was calibrated and subsequently the axial
and the radial distribution of the bulk density of
the sample were determined. Using a mathematic
method, the discrete measured data of bulk density
were mapped into 2D consecutive distribution images.
A comparison of calculated and experimental
results was performed to give deep insight into the
reaction mechanism and to optimize the 2D mode.
Key words: Carbon/carbon composites; CVI; bulk
density; X-ray; simulation; measurement.