Journal of Thermal Spray Technology

, Volume 24, Issue 5, pp 848–856 | Cite as

Evaluation of Generation Mechanism of Vertical Cracks in Top Coat of TBCs During APS Deposition by Laser AE Method

Peer Reviewed
First Online:
Received:
Revised:

Abstract

Vertical cracks can be generated in the top coat of thermal barrier coatings (TBCs) deposited by atmospheric plasma spraying (APS). Since they are known to improve the durability of TBCs such as in the case of dense vertically cracked TBC, clarification of the mechanism and the criteria of cracking are very important. In this study, generation of such vertical cracks was monitored during APS process by laser acoustic emission (AE) method, which is an in situ, non-contact, and non-destructive technique. Temperature was also monitored inside and on the surface of a specimen during APS process for estimation of the temperature field in the top coat. Results of the AE and temperature monitoring were combined to evaluate the relationship between cracking and thermal stress in the top coat. Most of the AE events due to the generation of vertical cracks were detected during rapid heating of the surface of the top coat by the heat flux from the torch. It showed that the vertical cracks were induced due to the tensile stress caused by the temperature difference in the top coat from the rapid heating. Furthermore, the estimated critical thermal stress for vertical cracking from the monitoring results was consistent with a previously reported strength of YSZ coating deposited by thermal spray.

Keywords

acoustic emission atmospheric plasma spray (APS) segmented coatings thermal stress 
This is a preview of subscription content, log in to check access.

Notes

Acknowledgment

We thank Mr. Hiraoka and Mr. Komatsu for supporting fabrication of our equipment and operation of the APS system. This work was partially supported by MEXT/JSPS KAKENHI Grant Number 23246124.

References

  1. 1.
    N.P. Padture, M. Gell, and E.H. Jordan, Thermal Barrier Coatings for Gas-Turbine Engine Applications, 2002, 296, p 280-284Google Scholar
  2. 2.
    R.A. Miller, Current Status of Thermal Barrier Coatings—An Overview, Surf. Coat. Technol., 1987, 30, p 1-11CrossRefGoogle Scholar
  3. 3.
    S. Kuroda and T.W. Clyne, The Quenching Stress in Thermally Sprayed Coatings, Thin Solid Films, 1991, 200, p 49-66CrossRefGoogle Scholar
  4. 4.
    T.A. Taylor, US Patent 5073433, 1989.Google Scholar
  5. 5.
    D.M. Gray, Y.C. Lau, C.A. Johnson, M.P. Boron, and W.A. Nelson, US Patent 5830586, 1996.Google Scholar
  6. 6.
    A.G. Evans, D.R. Mumm, J.W. Hutchinson, G.H. Meier, and F.S. Pettit, Mechanisms Controlling the Durability of Thermal Barrier Coatings, Progress Mater. Sci., 2001, 46, p 505-553CrossRefGoogle Scholar
  7. 7.
    M. Karger, R. Vaßen, and D. Stöver, Atmospheric Plasma Sprayed Thermal Barrier Coatings with High Segmentation Crack Densities, Spraying Process, Microstructure and Thermal Cycling Behavior, Surf. Coat. Technol., 2011, 206, p 16-23CrossRefGoogle Scholar
  8. 8.
    K. Sfar, J. Aktaa, and D. Munz, Numerical Investigation of Residual Stress Fields and Crack Behavior in TBC Systems, Mater. Sci. Eng A, 2002, 333, p 351-360CrossRefGoogle Scholar
  9. 9.
    H.B. Guo, S. Kuroda, and H. Murakami, Segmented Thermal Barrier Coatings Produced by Atmospheric Plasma Spraying Hollow Powders, Thin Solid Films, 2006, 506–507, p 136-139CrossRefGoogle Scholar
  10. 10.
    H.B. Guo, S. Kuroda, and H. Murakami, Microstructures and Properties of Plasma-sprayed Segmented Thermal Barrier Coatings, J. Am. Ceram. Soc., 2006, 89, p 1432-1439CrossRefGoogle Scholar
  11. 11.
    M. Watanabe, M. Enoki, and T. Kishi, Fracture Behavior of Ceramic Coatings During Thermal Cycling Evaluated by Acoustic Emission Method Using Laser Interferometers, Mater. Sci. Eng. A, 2003, 359, p 368-374CrossRefGoogle Scholar
  12. 12.
    S. Nishinoiri, M. Enoki, and K. Tomita, Evaluation of Microfracture Mode in Ceramic Coating During Thermal Cycle Test Using Laser AE Technique, Mater. Trans., 2004, 45, p 92-101CrossRefGoogle Scholar
  13. 13.
    S. Nishinoiri, M. Enoki, and K. Tomita, In Situ Monitoring of Microfracture During Plasma Spray Coating by Laser AE Technique, Sci. Technol. Adv. Mater., 2003, 4, p 623-631CrossRefGoogle Scholar
  14. 14.
    K. Taniguchi, M. Enoki, M. Watanabe, S. Kuroda, and K. Ito, In-Situ Monitoring of Cracking Behaviors of Plasma Sprayed Coatings by the Laser Acoustic Emission Technique, J. Mater. Res., 2009, 24, p 3182-3189CrossRefGoogle Scholar
  15. 15.
    K. Ito, S. Ohmata, K. Kobayashi, M. Watanabe, S. Kuroda, and M. Enoki, Crack Monitoring during Plasma Spraying of Ceramic Coatings by Non-Contact Acoustic Emission Method, Mater. Trans., 2010, 51, p 1272-1276CrossRefGoogle Scholar
  16. 16.
    H.W. Ng and Z. Gan, A Finite Element Analysis Technique for Predicting as-Sprayed Residual Stresses Generated by the Plasma Spray Coating Process, Finite Elem. Anal. Design, 2005, 41, p 1235-1254CrossRefGoogle Scholar
  17. 17.
    K. Ito, H. Kuriki, M. Watanabe, S. Kuroda, and M. Enoki, Detection of AE Events Due to Cracks in TBC During Spraying Process, Mater. Trans., 2012, 53, p 671-675CrossRefGoogle Scholar
  18. 18.
    K. Ito, H. Kuriki, H. Araki, S. Kuroda, and M. Enoki, Detection of Segmentation Cracks in Top Coat of TBCs During APS by Non-Contact AE Method, Sci. Technol. Adv. Mater., 2014, 15, p 035007CrossRefGoogle Scholar
  19. 19.
    K. Ito and M. Enoki, Acquisition and Analysis of Continuous Acoustic Emission Waveform for Classification of Damage Sources in Ceramic Fiber Mat, Mater. Trans., 2007, 48, p 1221-1226CrossRefGoogle Scholar
  20. 20.
    K. Ito, M. Watanabe, S. Kuroda, and M. Enoki, Evaluation of Cracking due to Dynamic Temperature Fluctuation during Plasma Spraying Process by Laser AE Method, Strength Fract. Complex., 2011, 7, p 177-183Google Scholar
  21. 21.
    S. Rangaraj and K. Kokini, Estimating the Fracture Resistance of Functionally Graded Thermal Barrier Coatings from Thermal Shock Tests, Surf. Coat. Technol., 2003, 173, p 201-212CrossRefGoogle Scholar
  22. 22.
    K.A. Khor, Y.W. Gu, and Z.L. Dong, Mechanical Behavior of Plasma Sprayed Functionally Graded YSZ/NiCoCrAlY Composite Coatings, Surf. Coat. Technol., 2001, 139, p 200-206CrossRefGoogle Scholar

Copyright information

© ASM International 2015

Authors and Affiliations

  • K. Ito
    • 1
  • H. Kuriki
    • 1
  • H. Araki
    • 2
  • S. Kuroda
    • 2
  • M. Enoki
    • 1
  1. 1.The University of TokyoTokyoJapan
  2. 2.National Institute for Materials ScienceTsukubaJapan

Personalised recommendations