Chapter 26. Stability of a Sapphire/Yttrium Aluminum Garnet Composite System

  1. John B. Wachtman Jr.
  1. L. E. Matson1,
  2. R. S. Hay1 and
  3. T. Mah2

Published Online: 26 MAR 2008

DOI: 10.1002/9780470310557.ch26

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

Matson, L. E., Hay, R. S. and Mah, T. (1989) Stability of a Sapphire/Yttrium Aluminum Garnet Composite System, 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.ch26

Author Information

  1. 1

    Air Force Wright Aeronautical Materials Laboratory WPAFB, OH

  2. 2

    Universal Energy Systems, Inc. Dayton, OH

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 deposition;
  • fiber-reinforced ceramic composites;
  • chemical vapor infiltration;
  • high fracture toughness;
  • carbon-carbon composites

Summary

Sapphire filaments were vacuum hot-pressed at 1500°–1650°C in a yttrium aluminum garnet (YAG) powder matrix. The YAG powders were derived from alkoxide precursors. A fully dense composite with a YAG grain size of 1-5 pun was obtained. Some samples were heat-treated further for 75 h at 1400°C in air. No evidence of second-phases along interfaces, or of chemical reaction between the sapphire and YAG, was observed by optical microscopy, electron microprobe, or analytical TEM. However, triple junction equilibrium between YAG grain boundaries and YAG/sapphire interphase boundaries resulted in a cusped YAG/sapphire interface. Triple junction angles indicate that YAG grain boundaries and YAG/alumina interphase boundaries have nearly equal interface energies. Lack of a smooth YAG/sapphire interface is anticipated to cause poor pull-out properties.