Chapter 39. Cvd Process for Si-N-O Fiber Growth Controlled by In-Situ Ftir Spectroscopic Monitoring

  1. Todd Jessen and
  2. Ersan Ustundag
  1. U. Vogt1,
  2. A. Vital1,
  3. T. Graule1,
  4. W. Graehlert2,
  5. M. Leparoux2,
  6. V. Hopfe2,
  7. H. C. Ewing3,
  8. R. Daum4 and
  9. A. Beil4

Published Online: 28 MAR 2008

DOI: 10.1002/9780470294635.ch39

24th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: B: Ceramic Engineering and Science Proceedings, Volume 21, Issue 4

24th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: B: Ceramic Engineering and Science Proceedings, Volume 21, Issue 4

How to Cite

Vogt, U., Vital, A., Graule, T., Graehlert, W., Leparoux, M., Hopfe, V., Ewing, H. C., Daum, R. and Beil, A. (2000) Cvd Process for Si-N-O Fiber Growth Controlled by In-Situ Ftir Spectroscopic Monitoring, in 24th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: B: Ceramic Engineering and Science Proceedings, Volume 21, Issue 4 (eds T. Jessen and E. Ustundag), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470294635.ch39

Author Information

  1. 1

    Swiss Federal Laboratories for Materials Testing and Research (EMPA), Section High Performance Ceramics, CH — 8600 Duebendorf

  2. 2

    Fraunhofer Institute of Material and Beam Technology, Winterbergstrasse 28, D-01277 Dresden, Germany

  3. 3

    University of Strathclyde, Mechanical Eng., Glasgow G1 IXN, UK

  4. 4

    Bruker Saxonia Analytik GmbH, Permoserstraße 15, D-04318 Leipzig, Germany

Publication History

  1. Published Online: 28 MAR 2008
  2. Published Print: 1 JAN 2000

ISBN Information

Print ISBN: 9780470375693

Online ISBN: 9780470294635

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Keywords:

  • stoichiometric precursor powder;
  • nucleation occurs;
  • fourier transformed infrared;
  • silicon oxynitride fibers;
  • thermodynamic studies

Summary

High-performance amorphous Si-N-O fibers are grown by a high temperature chemical vapor deposition (CVD) process. The fibers are grown at 1450°C by exposing a stoichiometric precursor powder mixture of SiO2 + SiC to flowing NH3. The reaction has been found to occur by a two stage reaction mechanism, the first involving the production of SiO(g) by the reduction of SiO2 by SiC, and the second the ammonolysis of SiO(g) by NH3 or related radicals NH·2 or NH·. Nucleation occurs on the surface of the SiO2 precursor by the reaction between adsorbed NHx molecules and SiO(g). The fibers grow initially as thin filaments from the fiber tip and continue to grow in the longitudinal direction, provided the supply of reactants is sufficient. Simultaneous deposition of material on the surface occurs, resulting in radial growth. The overall volume growth rate was found to be controlled by a surface adsorption reaction.

Measurements of the reaction gases have been carried out by mass spectrometry and gas chromatography. In order to improve CVD process control, an in-situ Fourier Transformed Infrared (FTIR) monitoring system has been developed. The set-up allows the measurement of the hot gas atmosphere directly above the precursor powder mixture. In addition to the decomposition of NH3, different reaction products have been identified, such as CO, HCN and CH4. Gaseous SiO species could be detected which are proposed to be responsible for the silicon transport in the gas phase from the solid SiO2 precursor powder to the fiber growth location. The interpretation of the high temperature spectra has been supported by spectra calculations.