Chapter 59. Silicon Nitride at Very High Temperatures: Bubble and Pit Formation

  1. J. P. Singh
  1. K. G. Nickel and
  2. E. Butchereit

Published Online: 26 MAR 2008

DOI: 10.1002/9780470294437.ch59

Proceedings of the 21st Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A: Ceramic Engineering and Science Proceedings, Volume 18, Issue 3

Proceedings of the 21st Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A: Ceramic Engineering and Science Proceedings, Volume 18, Issue 3

How to Cite

Nickel, K. G. and Butchereit, E. (1997) Silicon Nitride at Very High Temperatures: Bubble and Pit Formation, in Proceedings of the 21st Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A: Ceramic Engineering and Science Proceedings, Volume 18, Issue 3 (ed J. P. Singh), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470294437.ch59

Author Information

  1. Eberhard-Karls- Universität Tübingen Institut für Mineralogie, Petrologie und Geochemie D-72074 Tübingen, F.R.G.

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 1997

ISBN Information

Print ISBN: 9780470375495

Online ISBN: 9780470294437

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Keywords:

  • sintered ceramics;
  • phase equilibrium;
  • metastable amorphous solids;
  • atmospheric pressure;
  • oxidising atmospheres

Summary

From oxidation studies of sintered ceramics and pure Si3N4 and phase equilibrium studies it is concluded that the bubble formation in scales and the bloating of powder compacts have a common cause. This common cause is thought to be the formation of ”native oxides”, which are metastable amorphous solids of the type SiNxOy. As the eutectic temperature of the system is approached they recrystallise or decompose. The latter case leads to the bubbling/bloating. In pure Si3N4 this is in the vicinity of 1600°C at atmospheric pressure and defines the upper HT-limit of use. Pit formation seems to require bubble formation but not vice versa. Pits probably form at surface defects. They interact with microcracks forming during mechanical loading in oxidising atmospheres at high temperatures.