Chapter 56. Sintering and Cyclic Failure Mechanisms of Thermal and Environmental Barrier Coating Systems Under Thermal Gradient Test Conditions

  1. Hau-Tay Lin and
  2. Mrityunjay Singh
  1. Dongming Zhu,
  2. Kang N. Lee and
  3. Robert A. Miller

Published Online: 26 MAR 2008

DOI: 10.1002/9780470294758.ch56

26th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: B: Ceramic Engineering and Science Proceedings, Volume 23, Issue 4

26th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: B: Ceramic Engineering and Science Proceedings, Volume 23, Issue 4

How to Cite

Zhu, D., Lee, K. N. and Miller, R. A. (2002) Sintering and Cyclic Failure Mechanisms of Thermal and Environmental Barrier Coating Systems Under Thermal Gradient Test Conditions, in 26th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: B: Ceramic Engineering and Science Proceedings, Volume 23, Issue 4 (eds H.-T. Lin and M. Singh), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470294758.ch56

Author Information

  1. NASA John H. Glenn Research Center, Cleveland, Ohio 44135, USA

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2002

ISBN Information

Print ISBN: 9780470375792

Online ISBN: 9780470294758

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Keywords:

  • sintering;
  • thermal barrier coatings;
  • environmental barrier coatings;
  • ceramic matrix composite;
  • substrate heating

Summary

Plasma-sprayed ZrO2–8wt%Y2O3 and mullite+BSAS/Si multilayer thermal and environmental barrier coating (TBC–EBC) systems on SiC/SiC ceramic matrix composite (CMC) substrates were thermally cyclic tested under high thermal gradients using a laser high-heat-flux rig in conjunction with furnace exposure in water-vapor environments. Coating sintering and interface damage were assessed by monitoring the real-time thermal conductivity changes during the laser heat-flux tests and by examining the microstructural changes after exposure. Sintering kinetics of the coating systems were also independently characterized using a dilatometer. It was found that the coating failure involved both the time-temperature dependent sintering and the cycle frequency dependent cyclic fatigue processes. The water vapor environment not only facilitated the initial coating conductivity increases due to enhanced sintering and interface reaction, but also promoted later conductivity reductions due to the accelerated coating cracking and delamination. The failure mechanisms of the coating systems are also discussed based on the cyclic test results and are correlated to the sintering and thermal stress behavior under the thermal gradient test conditions.