Journal of Thermal Spray Technology

, Volume 9, Issue 2, pp 175–180 | Cite as

Thermal conductivity and elastic modulus evolution of thermal barrier coatings under high heat flux conditions

  • Dongming Zhu
  • Robert A. Miller


Laser high heat flux test approaches have been established to obtain critical properties of ceramic thermal barrier coatings (TBCs) under near-realistic temperature and thermal gradients that may be encountered in advanced engine systems. Thermal conductivity change kinetics of a thin ceramic coating were continuously monitored in real time at various test temperatures. A significant thermal conductivity increase was observed during the laser-simulated engine heat flux tests. For a 0.25 mm thick ZrO2-8% Y2O3 coating system, the overall thermal conductivity increased from the initial value of 1.0 W/m K to 1.15, 1.19, and 1.5 W/m K after 30 h of testing at surface temperatures of 990, 1100, and 1320 °C, respectively, Hardness and elastic modulus gradients across a 1.5 mm thick TBC system were also determined as a function of laser testing time using the laser sintering/creep and microindentation techniques. The coating Knoop hardness values increased from the initial hardness value of 4 GPa to 5 GPa near the ceramic/bond coat interface and to 7.5 GPa at the ceramic coating surface after 120 h of testing. The ceramic surface modulus increased from an initial value of about 70 GPa to a final value of 125 GPa. The increase in thermal conductivity and the evolution of significant hardness and modulus gradients in the TBC systems are attributed to sintering-induced microporosity gradients under the laser-imposed high thermal gradient conditions. The test techniques provide a viable means for obtaining coating data for use in design, development, stress modeling, and life prediction for various TBC applications.


thermal barrier coating laser sintering and creep thermal conductivity change kinetics elastic modulus 


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  1. 1.
    “CMSX Property Data,” Cannon-Muskegon Corporation, Muskegon, MI, 1994.Google Scholar
  2. 2.
    J.T. DeMasi, K.D. Sheffler, and M. Ortiz: “Thermal Barrier Coating Life Prediction Model Development: Phase I-Final Report,” NASA CR-182230, NASA, Washington, DC, Dec. 1989.Google Scholar
  3. 3.
    R.A. Miller and G.W. Leissler: “Characterization and Durability Testing of Plasma-Sprayed Zirconia-Yttria and Hafnia-Yttria Thermal Barrier Coatings,” NASA Technical Paper 3296, NASA, Washington, DC, Mar. 1993.Google Scholar
  4. 4.
    D. Zhu and R.A. Miller: “Determination of Thermal Conductivity Change Kinetics under Steady-State Laser Heat Flux Conditions,” NASA Technical Memorandum, 209069, NASA, Washington, DC, 1999.Google Scholar
  5. 5.
    C.H. Liebert: “Emittance and Absorptance of NASA Ceramic Thermal Barrier Coating System,” NASA Technical Paper TP-1190, NASA, Washington, DC, 1978.Google Scholar
  6. 6.
    C.H. Liebert: “Emittance and Absorptance of the National Aeronautics and Space Administration Ceramic Thermal Barrier Coating,” Thin Solid Films, 1978, vol. 53, pp. 235–40.CrossRefGoogle Scholar
  7. 7.
    D. Zhu and R.A. Miller: “Determination of Creep Behavior of Thermal Barrier Coatings under Laser Imposed Temperature and Stress Gradients,” NASA Technical Memorandum 113169, Army Research Laboratory Report ARL-TR-1565, Nov. 1997; also in J. Mater. Res., 1999, vol. 14, pp 146–61.Google Scholar
  8. 8.
    D.B. Marshall, T. Noma, and A.G. Evans: J. Am. Ceram. Soc., 1982, vol. 65, pp. C175-C176.CrossRefGoogle Scholar
  9. 9.
    S.-H. Leigh, C.-K. Lin, and C.C. Berndt: J. Am. Ceram. Soc., 1997, vol. 80, pp. 2093–99.CrossRefGoogle Scholar
  10. 10.
    J.P. Singh, M. Sutaria, and M. Ferber: Ceram. Eng. Sci. Proc., 1997, vol. 18, pp. 191–200.CrossRefGoogle Scholar
  11. 11.
    H.E. Eaton, J.R. Linsey, and R.B. Dinwiddie: “The Effect of Thermal Aging on the Thermal Conductivity of Plasma Sprayed Fully Stabilized Zirconia,” Thermal Conductivity, vol. 22, T.W. Tong, Ed.: Technomic Publishing Co., Inc., Lancaster, Pennsylvania, 1994, pp. 289–300.Google Scholar
  12. 12.
    R.B. Dinwiddie, S.C. Beecher, W.D. Porter, and B.A. Nagaraj: “The Effect of Thermal Aging on the Thermal Conductivity of Plasma Sprayed and EB-PVD Thermal Barrier Coatings,” presented at The International Gas Turbine and Aeroengine Congress and Exhibition, Birmingham, UK, ASME Paper 96-GT-282, 1996.Google Scholar

Copyright information

© ASM International 2000

Authors and Affiliations

  • Dongming Zhu
    • 1
  • Robert A. Miller
    • 2
  1. 1.Ohio Aerospace Institute, National Aeronautics and Space AdministrationGlenn Research CenterUSA
  2. 2.National Aeronautics and Space Administration, Glenn Research CenterCleveland

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