Chapter 42. NMR Study of Redistribution Reactions in Blackglas™ and their Influence on Oxidative Stability

  1. John B. Wachtman Jr.
  1. M. A. B. Meador1,
  2. F. I. Hurwitz1 and
  3. S. T. Gonczy2

Published Online: 28 MAR 2008

DOI: 10.1002/9780470314876.ch42

Proceedings of the 20th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - B: Ceramic Engineering and Science Proceedings, Volume 17, Issue 4

Proceedings of the 20th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - B: Ceramic Engineering and Science Proceedings, Volume 17, Issue 4

How to Cite

Meador, M. A. B., Hurwitz, F. I. and Gonczy, S. T. (2008) NMR Study of Redistribution Reactions in Blackglas™ and their Influence on Oxidative Stability, in Proceedings of the 20th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - B: Ceramic Engineering and Science Proceedings, Volume 17, Issue 4 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470314876.ch42

Author Information

  1. 1

    NASA Lewis Research Center Cleveland, OH

  2. 2

    Allied Signal Corp. 800 °C. Des Plaines, IL

Publication History

  1. Published Online: 28 MAR 2008
  2. Published Print: 1 JAN 1996

ISBN Information

Print ISBN: 9780470375433

Online ISBN: 9780470314876

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Keywords:

  • tetrahedral bondin;
  • nuciear magnetic resonance spectroscop;
  • empirical model;
  • statistical experimental design;
  • substantial weight loss

Summary

Previous work has shown that silicon oxycarbides, including Blackglas™, undergo bond redistribution with very minimal (< 1 percent) weight loss at temperatures above 800 °C. In this paper, the influence of pyrolysis temperature and time on these redistribution reactions, and the resultant effect on oxidative stability of Blackglas™ powders was studied. Tetrahedral bonding of C and O to Si was followed using 29Si nuclear magnetic resonance spectroscopy for both as pyrolyzed samples and samples oxidized at 600 °C. A statistical experimental design approach was employed to minimize experiments and allow for derivation of an empirical model to optimize pyrolysis parameters. Si-C bonding of the oxycarbide and oxidative stability were found to increase with increasing pyrolysis temperature over the temperature range of 900 to 1100 °C. Pyrolysis time over the range of 1 to 5 hours was not found to have a significant influence on the redistribution reactions. Based on the behavior of the matrix alone, pyrolysis at 1100 °C is recommended to optimize the 600 °C oxidative stability of Blackglas™ ceramics.