Chapter 2. The Evolution of Interfacial Sliding Stresses During Cyclic Push-in Testing of C- and Bn-Coated Hi-Nicalon Fiber-Reinforced CMCs

  1. Don Bray
  1. J. I. Eldridge,
  2. N. P. Bansal and
  3. R. T. Bhatt

Published Online: 26 MAR 2008

DOI: 10.1002/9780470294482.ch2

22nd Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A: Ceramic Engineering and Science Proceedings, Volume 19, Issue 3

22nd Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A: Ceramic Engineering and Science Proceedings, Volume 19, Issue 3

How to Cite

Eldridge, J. I., Bansal, N. P. and Bhatt, R. T. (2008) The Evolution of Interfacial Sliding Stresses During Cyclic Push-in Testing of C- and Bn-Coated Hi-Nicalon Fiber-Reinforced CMCs, in 22nd Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A: Ceramic Engineering and Science Proceedings, Volume 19, Issue 3 (ed D. Bray), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470294482.ch2

Author Information

  1. NASA Lewis Research Center, Cleveland, OH 44135

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 1988

ISBN Information

Print ISBN: 9780470375587

Online ISBN: 9780470294482

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Keywords:

  • environment;
  • aluminosilicate;
  • composites;
  • moisture;
  • strontium

Summary

Interfacial debond cracks and fiber/matrix sliding stresses in ceramic matrix composites (CMCs) can evolve under cyclic fatigue conditions as well as with changes in the environment, strongly affecting the crack growth behavior, and therefore, the useful service lifetime of the composite. In this study, room temperature cyclic fiber push-in testing was applied to monitor the evolution of frictional sliding stresses and fiber sliding distances with continued cycling in both C-and BN-coated Hi-Nicalon SiC fiber-reinforced CMCs. A SiC matrix composite reinforced with C-coated Hi-Nicalon fibers as well as barium strontium aluminosilicate (BSAS) matrix composites reinforced with BN-coated (four different deposition processes compared) Hi-Nicalon fibers were examined. For failure at a C interface, test results indicated progressive increases in fiber sliding distances during cycling in room air but not in nitrogen. These results suggest the presence of moisture will promote crack growth when interfacial failure occurs at a C interface. While shortterm testing environmental effects were not apparent for failure at the BN interfaces, long-term exposure of partially debonded BN-coated fibers to humid air resulted in large increases in fiber sliding distances and decreases in interfacial sliding stresses for all the BN coatings, presumably due to moisture attack. A wide variation was observed in debond and frictional sliding stresses among the different BN coatings.