Chapter 81. Coating of Bn Interfaces on Ceramic Yarns from Boric Acid and Ammonia

  1. John B. Wachtman Jr.
  1. Lu Shen,
  2. William S. Willis,
  3. Francis S. Galasso and
  4. Steven L. Suib

Published Online: 28 MAR 2008

DOI: 10.1002/9780470314180.ch81

Proceedings of the 17th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 14, Issue 7/8

Proceedings of the 17th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 14, Issue 7/8

How to Cite

Shen, L., Willis, W. S., Galasso, F. S. and Suib, S. L. (1993) Coating of Bn Interfaces on Ceramic Yarns from Boric Acid and Ammonia, in Proceedings of the 17th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 14, Issue 7/8 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470314180.ch81

Author Information

  1. U-60, Dept. of Chemistry and Institute of Material Science, University of Connecticut, Storrs, CT 06269-3060.

Publication History

  1. Published Online: 28 MAR 2008
  2. Published Print: 1 JAN 1993

ISBN Information

Print ISBN: 9780470375266

Online ISBN: 9780470314180

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Keywords:

  • crystallization;
  • degradation;
  • ceramic fibers;
  • nitridation process;
  • methyltrichlorosilane

Summary

BN coatings have been formed on individual fibers in several different ceramic yarns via dip or wick coating in boric acid solution followed by reaction with NH3 gas. The control of the crystallization of H3BO3 on the fibers plays an important role in the coating evenness and in the prevention of bridging between fibers. The coated fibers have been characterized by SEM, AES and tested using an Instron tensile strength tester. The BN-coated Tyranno fibers were only slightly degraded, while Nextel, Nicalon and Sumitoma fibers were severely degraded by the coating process. However, smooth BN coatings without much fiber bridging or fiber degradation, have been made on pre-carbon-coated Nicalon (C-Nicalon) yarns. Chemical vapor infiltrated SiC matrices were introduced into BN-coated C-Nicalon fiber bundles, and the SiC/BN/SiC single strand composites had a tensile strength of 207 MPa (30 ksi), and the fracture surfaces exhibited good fiber pull-out.