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Effect of the Starting Microstructure on the Thermal Properties of As-Sprayed and Thermally Exposed Plasma-Sprayed YSZ Coatings

Authors

  • Yang Tan,

    Corresponding author
    1. Center for Thermal Spray Research, State University of New York at Stony Brook, Stony Brook, New York 11794-2275
      †Author to whom correspondence should be addressed. e-mail: yangtan@gmail.com
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    • *Member, the American Ceramic Society.

  • Jon P. Longtin,

    1. Center for Thermal Spray Research, State University of New York at Stony Brook, Stony Brook, New York 11794-2275
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  • Sanjay Sampath,

    1. Center for Thermal Spray Research, State University of New York at Stony Brook, Stony Brook, New York 11794-2275
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    • *Member, the American Ceramic Society.

  • Hsin Wang

    1. High Temperature Materials Laboratory, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6064
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    • *Member, the American Ceramic Society.


  • N. Padture—contributing editor

  • This work was financially supported by the GOALI-FRG program sponsored by National Science Foundation under award CMMI 0605704. The high-temperature thermal conductivity measurement conducted at Oak Ridge is supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies, as part of the High Temperature Materials Laboratory User Program at Oak Ridge National Laboratory managed by the UT-Battelle LLC for the Department of Energy under contract DE-AC05000OR22725.

†Author to whom correspondence should be addressed. e-mail: yangtan@gmail.com

Abstract

Thermal barrier coatings (TBCs) experience thermal gradients, excessive temperature, and high heat flux from hot gases in turbines during service. These extended thermal effects induce sintering and significant microstructure changes, which alter the resulting thermal conductivity of the TBCs. To study the effects of different starting microstructures on the sintering behavior, plasma-sprayed yttria-stabilized zirconia (YSZ) TBCs produced from different starting powders and process parameters were subjected to thermal aging at several temperatures and time intervals, after which their thermal conductivity was measured at room temperature. The thermal conductivity results were analyzed by introducing the Larson–Miller parameter, that describes the creep-like behavior of thermal conductivity increase with annealing temperature and time. One set of coatings was also annealed under the same conditions and the thermal conductivities were measured at elevated temperatures. The temperature-dependent thermal conductivity data were analyzed and used to predict the long-term thermal property behavior for a general YSZ coating design.

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