Chapter 37. Variations in the Structure and Morphology of Pyrolytic Boron Nitride

  1. John B. Wachtman Jr.
  1. A. W. Moore1 and
  2. S. L. Strong2

Published Online: 26 MAR 2008

DOI: 10.1002/9780470310557.ch37

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

Moore, A. W. and Strong, S. L. (1989) Variations in the Structure and Morphology of Pyrolytic Boron Nitride, 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.ch37

Author Information

  1. 1

    Union Carbide Coatings Service Corporation 12900 Snow Road Parma, OH

  2. 2

    UCAR Carbon Company Inc., A Union Carbide Company' 12900 Snow Road Parma, 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 infiltration;
  • pyrolytic boron nitride;
  • graphite furnace;
  • ceramics;
  • x-ray diffraction

Summary

Three types of structure/morphology have been observed in pyrolytic boron nitride (PBN) made from mixtures of boron trichloride and ammonia. One of the structures is purely turbostratic (co/2 > 3.40Å) like that of pyrolytic carbon. A second structure is more crystalline (co/2 = 3.34-3.35Å) and is found in PBN of high density (>2.20 g/cc). A third type of PBN shows two or three peaks in the X-ray preferred orientation (rocking) curves, in which the outer peaks are separated by 70–75°. These peaks are due to a columnar microcrystalline component in the PBN, probably caused by twinning. Attempts to dope with certain impurities caused a strong enhancement of the crystallinity and orientation of PBN with this morphology. The effects of the structure/morphology variations on PBN properties, such as thermal expansion, are discussed.