46. Characterization of Si3N4 Bars Extracted from Various Regions of a Billet by Resonance and Flex Testing

  1. Edgar Lara-Curzio and
  2. Michael J. Readey
  1. G. Ojard1,
  2. T. Barnett2,
  3. M. Ferber3 and
  4. K. Johnson4

Published Online: 26 MAR 2008

DOI: 10.1002/9780470291191.ch46

28th International Conference on Advanced Ceramics and Composites B: Ceramic Engineering and Science Proceedings, Volume 25, Issue 4

28th International Conference on Advanced Ceramics and Composites B: Ceramic Engineering and Science Proceedings, Volume 25, Issue 4

How to Cite

Ojard, G., Barnett, T., Ferber, M. and Johnson, K. (2004) Characterization of Si3N4 Bars Extracted from Various Regions of a Billet by Resonance and Flex Testing, in 28th International Conference on Advanced Ceramics and Composites B: Ceramic Engineering and Science Proceedings, Volume 25, Issue 4 (eds E. Lara-Curzio and M. J. Readey), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470291191.ch46

Author Information

  1. 1

    Pratt & Whitney 400 Main Street East Hartford, CT 06108

  2. 2

    Southern Research Institute 757 Torn Martin Drive Birmingham, AL 35211

  3. 3

    Oak Ridge National Labs Bethel Valley Road Oak Ridge, TN 37831

  4. 4

    Quasar International 5500 Midway Park Place NE Albuquerque, NM 87109

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2004

ISBN Information

Print ISBN: 9780470051528

Online ISBN: 9780470291191

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Keywords:

  • automated laser-scattering system;
  • nondestructive evaluation;
  • silicon-nitride engine;
  • industrial engines;
  • natural gas

Summary

Typically, ceramics are characterized in the fully machined state eliminating any as-processed surface from the material database. An effort was undertaken to understand the effect of the as-processed surface. A billet of Si3N4 was machined into 80 flex bars. Half of the flex bars were fully machined from the center of the billet. The remaining samples were machined leaving one face with the as-processed surface (the tensile surface of the flex bar). The samples were then characterized by resonant ultrasound spectroscopy; ultrasonic velocity measurement, surface roughness and mechanical flex testing. The testing showed that the material broke into two sets of data. The as-processed samples had a lower modulus and lower strength. Remachining of the half of the as-processed samples returned the strength but the modulus was still lower than the standard samples. The strength debit is due to surface flaws present in the as-processed surface that can be removed. The modulus changed due to the presence of sintering aids and as-processed surface effects. The results of this testing will be shown and conclusions drawn.