20. Producing Surface Coatings on Silicon Nitride by Pack Cementation

  1. Dongming Zhu and
  2. Kevin Plucknett
  1. S. D. Nunn,
  2. R. A. Lowden and
  3. F. C. Montgomery

Published Online: 26 MAR 2008

DOI: 10.1002/9780470291238.ch20

Advances in Ceramic Coatings and Ceramic-Metal Systems: Ceramic Engineering and Science Proceedings, Volume 26, Number 3

Advances in Ceramic Coatings and Ceramic-Metal Systems: Ceramic Engineering and Science Proceedings, Volume 26, Number 3

How to Cite

Nunn, S. D., Lowden, R. A. and Montgomery, F. C. (2005) Producing Surface Coatings on Silicon Nitride by Pack Cementation, in Advances in Ceramic Coatings and Ceramic-Metal Systems: Ceramic Engineering and Science Proceedings, Volume 26, Number 3 (eds D. Zhu and K. Plucknett), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470291238.ch20

Author Information

  1. Oak Ridge National Laboratory P.O. Box 2008 Oak Ridge, TN 37831

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2005

ISBN Information

Print ISBN: 9781574982336

Online ISBN: 9780470291238

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Keywords:

  • atmosphere;
  • ceramic;
  • aluminosilicate;
  • microscopy;
  • crystalline

Summary

Pack cementation processing was used to chemically alter the surface of dense silicon nitride materials and form a coating layer. Test samples were examined by XRD, SEM, and optical microscopy to characterize the chemical and microstructural changes in the materials after processing. The coating that was formed depended on the composition of the reactive powder pack used in the process and on the processing conditions of temperature and furnace atmosphere. Some of the coating compounds identified by XRD, such as Yb2Si2O7, SrAl2Si2O8, and Yb3Al5O12, are promising candidate materials for protective environmental barrier coatings. Preliminary exposure testing results in water vapor at high temperature indicate that a Yb2Si2O7 coating on NT154 Si3N4 reduces the rate of attack compared to the uncoated material.