10. Formation of Needle-Like Grains in Al2O3

  1. John B. Wachtman Jr.
  1. D. E. García,
  2. J. Wendorff,
  3. R. Janssen and
  4. N. Claussen

Published Online: 28 MAR 2008

DOI: 10.1002/9780470314555.ch10

Proceedings of the 18th Annual Conference on Composites and Advanced Ceramic Materials - B: Ceramic Engineering and Science Proceedings, Volume 15, Issue 5

Proceedings of the 18th Annual Conference on Composites and Advanced Ceramic Materials - B: Ceramic Engineering and Science Proceedings, Volume 15, Issue 5

How to Cite

García, D. E., Wendorff, J., Janssen, R. and Claussen, N. (1994) Formation of Needle-Like Grains in Al2O3 , in Proceedings of the 18th Annual Conference on Composites and Advanced Ceramic Materials - B: Ceramic Engineering and Science Proceedings, Volume 15, Issue 5 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470314555.ch10

Author Information

  1. Advanced Ceramics Group Technische Universität Hamburg-Harburg D-21071 Hamburg, Germany

Publication History

  1. Published Online: 28 MAR 2008
  2. Published Print: 1 JAN 1994

ISBN Information

Print ISBN: 9780470375334

Online ISBN: 9780470314555

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Keywords:

  • alumina-based ceramics;
  • duplex microstructure;
  • formation of needles;
  • zirconium niobium aluminate phase;
  • high-aspect ratio grains

Summary

Alumina-based ceramics with duplex microstructure were manufactured by reaction bonding Al/Al2O3 precursor mixtures. Nb, ZrO2, and CaNO3 additions were used to initiate the formation of “needles” during synthesis as well as thermal treatment. It was found that simultaneous addition of Nb and ZrO2 leads to the development of a yet unknown zirconium niobium aluminate phase that can grow to high aspect ratios. The formation of these needles seems to be triggered by the presence of a liquid phase. Qualitative crack propagation determinations were used to demonstrate the benefit of these in-situ formed high-aspect ratio grains.