Chapter 15. Interfacial Chemistry-Structure and Fracture of Ceramic Composites

  1. John B. Wachtman Jr.
  1. R. H. Jones1,
  2. C. H. Henager Jr.1,
  3. C. H. Schilling1,
  4. L. H. Schoenlein1,
  5. W. J. Weber1 and
  6. F. Gac2

Published Online: 28 MAR 2008

DOI: 10.1002/9780470310496.ch15

Proceedings of the 12th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 9, Issue 7/8

Proceedings of the 12th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 9, Issue 7/8

How to Cite

Jones, R. H., Henager, C. H., Schilling, C. H., Schoenlein, L. H., Weber, W. J. and Gac, F. (1988) Interfacial Chemistry-Structure and Fracture of Ceramic Composites, in Proceedings of the 12th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 9, Issue 7/8 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470310496.ch15

Author Information

  1. 1

    Pacific Northwest Laboratory Richland, WA 99352

  2. 2

    Los Alamos National Laboratory Los Alamos, NM 87545

Publication History

  1. Published Online: 28 MAR 2008
  2. Published Print: 1 JAN 1988

ISBN Information

Print ISBN: 9780470374801

Online ISBN: 9780470310496

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Keywords:

  • monolithic;
  • ceramics;
  • delamination;
  • processing methods;
  • matrix material

Summary

The interfacial chemistry and structure of SiC/Si3N4 composites has been evaluated using TEM/STEM and AES. Nicalon™ Sic fiber reinforced hot-pressed Si3N4 and VLS single crystal Sic reinforced reaction-bonded silicon nitride (RBSN) have been evaluated. An amorphous carbon-graphite interface structure was observed in the Nicalon SiC fiber-reinforced material resulting from sizing used to assist fiber handling. Fiber pullout occurred upon fracture of the composite material with the fracture apparently occurring between the amorphous and graphitic carbon layers. The flexure strength of the composite was about one-third that of the matrix with the degradation apparently resulting from the development of a glass phase in the grain boundaries of the Nicalon during hot pressing. The interfaces of Si3N4 matrix composites with C, BN, SiO2 coated and untreated VLS whiskers were found to vary markedly. In the RBSN composites, the C was present in the form of a fibrous graphitic structure, the BN coating was nonexistent but large facets had formed on the whiskers while the SiO2 coating was present as a discontinuous glass phase. The composite with the SiO2 coated whiskers exhibited the highest fracture strength and toughness while the material made the BN-coated whiskers exhibited the lowest values.