23. The Notion of Densification Front in CVI Processing with Temperature Gradients

  1. Edgar Lara-Curzio
  1. Gerard L. Vignoles1,
  2. Nathalie Nadeau2,
  3. Claude-Michel Brauner2,
  4. Jean-François Lines3 and
  5. Jean-Rodolphe Puiggali3

Published Online: 26 MAR 2008

DOI: 10.1002/9780470291221.ch23

Mechanical Properties and Performance of Engineering Ceramics and Composites: Ceramic Engineering and Science Proceedings, Volume 26, Number 2

Mechanical Properties and Performance of Engineering Ceramics and Composites: Ceramic Engineering and Science Proceedings, Volume 26, Number 2

How to Cite

Vignoles, G. L., Nadeau, N., Brauner, C.-M., Lines, J.-F. and Puiggali, J.-R. (2005) The Notion of Densification Front in CVI Processing with Temperature Gradients, in Mechanical Properties and Performance of Engineering Ceramics and Composites: Ceramic Engineering and Science Proceedings, Volume 26, Number 2 (ed E. Lara-Curzio), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470291221.ch23

Author Information

  1. 1

    Lab. des Composites Thermo Structuraux (LCTS), Université Bordeaux 1 - 3, Allée La Boëtie, F 33600 Pessac, France

  2. 2

    Mathématiques Appliquées de Bordeaux (MAB), Université Bordeaux 1-351, Cours de la Libération, F 33405 Talence Cedex, France

  3. 3

    TRansferts Ecoulements FLuides Energetique (TREFLE), ENSAM - Esplanade des Arts et Métiers, F 33405 Talence, France

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2005

ISBN Information

Print ISBN: 9781574982329

Online ISBN: 9780470291221

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Keywords:

  • chemical vapor infiltration;
  • ceramic matrices;
  • surface tempcriitrirc;
  • thermal gradients;
  • heat conductivity

Summary

Many variants of the Chemical Vapor Infiltration (CVI) process make use of a thermal gradient, which allows to localize the densification reaction first in the parts of the preform which are most difficult to reach by precursor transport. When the process is well controlled, a densification front starts from these regions and moves towards the outside of the preform; however, the control of this front is difficult.

We propose a simple ID model of this front, based on the local energy and mass balances. The analytical and numerical study yield existence conditions and relate the front characteristics (i. e. width, velocity, residual porosity) to control parameters. The model results are validated with respect to experimental data, and process control guidelines are given.