Chapter 2. Improved Processing of CVI Composites

  1. John B. Wachtman Jr.
  1. R. A. Lowden1,
  2. D. P. Stinton1 and
  3. T. S. Starr2

Published Online: 26 MAR 2008

DOI: 10.1002/9780470310557.ch2

A Collection of Papers Presented at the 13th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 10, Issue 7/8

A Collection of Papers Presented at the 13th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 10, Issue 7/8

How to Cite

Lowden, R. A., Stinton, D. P. and Starr, T. S. (1989) Improved Processing of CVI Composites, in A Collection of Papers Presented at the 13th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 10, Issue 7/8 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470310557.ch2

Author Information

  1. 1

    Oak Ridge National Laboratory Oak Ridge, TN 37831-6063

  2. 2

    Georgia Tech Research Institute Atlanta, GA

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 1989

ISBN Information

Print ISBN: 9780470374863

Online ISBN: 9780470310557

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Keywords:

  • chemical vapor infiltration;
  • ceramic matrix composites;
  • carbon-carbon properties;
  • fiber-reinforced ceramic composites;
  • thermal vapor infiltration

Summary

An analytical model has been developed for the forced-flow/thermal-gradient chemical vapor infiltration process as applied to the Nicalon/SiC system. The model utilizes various substrate properties and deposition kinetics to predict the progress of infiltration. Preforms have been modeled to determine surface area/density relationships, and it has been shown that a 'series resistance' model for thermal conductivity exhibits good fit to experimental data. Model predictions based on these parameters and first-order deposition kinetics have shown excellent agreement with experimental trends. The model predicts an increase in the cool-face temperature and the differential pressure across the substrate that are directly related to the degree of densification. These parameters can be used to monitor and modify the infiltration process. An infiltration system has been equipped with a computer-interfaced process control and data acquisition system. The system has been used to monitor and alter conditions during infiltration, thus improving deposition efficiency and uniformity.