Chapter 57. An Investigation of the Microstructure in the Pest Oxide of a MoSi2- Based Composite

  1. Todd Jessen and
  2. Ersan Ustundag
  1. Jun Eu Tang1,
  2. Mats Halvarsson1,
  3. Anders Kvist1,
  4. Kristina Hansson2,
  5. Jan-Erik Svensson2 and
  6. Robert Pompe3

Published Online: 28 MAR 2008

DOI: 10.1002/9780470294635.ch57

24th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: B: Ceramic Engineering and Science Proceedings, Volume 21, Issue 4

24th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: B: Ceramic Engineering and Science Proceedings, Volume 21, Issue 4

How to Cite

Tang, J. E., Halvarsson, M., Kvist, A., Hansson, K., Svensson, J.-E. and Pompe, R. (2000) An Investigation of the Microstructure in the Pest Oxide of a MoSi2- Based Composite, in 24th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: B: Ceramic Engineering and Science Proceedings, Volume 21, Issue 4 (eds T. Jessen and E. Ustundag), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470294635.ch57

Author Information

  1. 1

    Dept. of Experimental Physics Chalmers/Goteborg University SE-41296 Gothenburg Sweden

  2. 2

    Dept. of Environmental Inorganic Chemistry Chalmers/Goteborg University SE-41296 Gothenburg Sweden Sweden

  3. 3

    Swedish Ceramic Institute Box 5403 SE-40229 Gothenburg Sweden

Publication History

  1. Published Online: 28 MAR 2008
  2. Published Print: 1 JAN 2000

ISBN Information

Print ISBN: 9780470375693

Online ISBN: 9780470294635

SEARCH

Keywords:

  • microanalysis;
  • pest oxide layer;
  • molybdenum;
  • catastrophic oxidation;
  • thermo gravimetric analysis

Summary

The pesting of MoSi2 was investigated by performing detailed microanalysis on the pest oxide layer. The studied material was a MoSi2-Mo5i3-clay composite which had undergone pest-oxidation for 4000 hours at 450°C. Results from detailed SEM and TEM studies, including quantitative EDX analysis, on the various features in the pest oxide are presented. It was found that MoSi2, as well as the MosSi3, transforms immediately into an oxide mixture of MoO3 nanocrystals and amorphous SiO2 with significant loss in molybdenum upon oxidation. With time, part of the oxide mixture cluster into lamellar MoO3 aggregates. These aggregates disappear from the oxide after even longer times, leaving voids in the oxide structure. This allows even quicker depletion of MoO3 from the oxide, leaving dark grey regions containing mostly SO2.