Chapter 38. Room and High Temperature Fatigue Damage Evaluation of SiCySi3N4 Composites

  1. John B. Wachtman Jr
  1. H. Mahfuz,
  2. M. Maniruzzaman,
  3. U. K. Vaidya,
  4. T. Brown and
  5. S. Jeelani

Published Online: 26 MAR 2008

DOI: 10.1002/9780470314715.ch38

Proceedings of the 19th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - A: Ceramic Engineering and Science Proceedings, Volume 16, Issue 4

Proceedings of the 19th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - A: Ceramic Engineering and Science Proceedings, Volume 16, Issue 4

How to Cite

Mahfuz, H., Maniruzzaman, M., Vaidya, U. K., Brown, T. and Jeelani, S. (1995) Room and High Temperature Fatigue Damage Evaluation of SiCySi3N4 Composites, in Proceedings of the 19th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - A: Ceramic Engineering and Science Proceedings, Volume 16, Issue 4 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470314715.ch38

Author Information

  1. Materials Research Laboratory, Tuskegee University Tuskegee, AL 36088

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 1995

ISBN Information

Print ISBN: 9780470375372

Online ISBN: 9780470314715

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Keywords:

  • catastrophic;
  • shear;
  • eccentric;
  • ultrasonic;
  • prominence

Summary

Monotonic tensile and fatigue response of continuous silicon carbide fiber reinforced silicon nitride (SiCf/Si3N4) matrix composites has been investigated. The monotonic tensile tests have been performed at room and elevated temperatures. Fatigue tests have been conducted at room temperature (RT), at a stress ratio, R=0.1 and a frequency of 5 Hz. Failure mechanisms under monotonic and fatigue loading have been identified through detailed optical microscopy (OM) and scanning electron microscopy (SEM). The monotonic tests on RT tested composites, resulted in catastrophic failure with irregular fiber surfaces, while the composites tested at 800°C failed catastrophically, exhibiting clean and smooth fiber surfaces. Composites tested at 1600°C showed progressive failure through multiple delaminations and fiber pull-out. In fatigue, all composites tested at RT failed in a catastrophic manner. The composites tested at 80% and 85% of ultimate tensile strength (out) exhibited a large scatter in fatigue life with evidence of large fiber pull-out lengths and eccentric load paths. The failure of the composites tested at 90% a it resembled that of the monotonic tensile specimens, showing less scatter in fatigue life and evidence of tensile cum shear fiber fracture and matrix cracks. Ultrasonic nondestructive evaluation (NDE) under A-scan configuration has been applied to characterize the composites based on variations in ultrasonic velocity. Weibull analysis of the monotonic and fatigue test results has also been presented.