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Detailed Program
Paper Number : AD-I01
Time Frame : 15:00~15:25
Presentation Date : Thurseday, 27, November
Session Name : Advanced Coating for Gas Turbines
Session Chair 1# : Yoonsuk Oh
Session Chair 2# : Shunkichi Ueno
Thermal Properties of Y2O3 doped ZrO2 Thermal Barrier Coatings
Byung-Koog JANG
National Institute for Materials Science
Thermal barrier coatings (TBCs) have received a large attention because they increase the thermal efficiency of gas turbine engines by increasing the gas turbine inlet temperature and reducing the amount of cooling air required for the hot section components. Electron beam-physical vapor deposition (EB-PVD) or plasma spray coatings is a widely used technique for depositing thermal barrier coatings (TBCs) on metal substrates for high temperature applications, such as gas turbines, in order to improve the thermal efficiency. The controlled microstructure of coatings is one of the most important properties for obtaining superior TBCs. To optimize TBCs for integration into gas turbines, characterization of the relationship between microstructure and thermal properties of the coatings is important [1,2]. This work describes the thermal properties of 2~8mol%Y2O3-stabilized ZrO2 (YSZ) coatings by EB-PVD. The thermal conductivity of the coated samples was measured by the pulsed thermal imaging method and the laser flash method. The YSZ coatings consist of porous-columnar grains containing nano pores. Nanosize pores could be observed around feather-like grains as well as inside of columnar grains. The thermal conductivity and thermal diffusivity of the coatings showed decreasing tendency with increasing porosity. In addition, both the thermal conductivity and heat capacity of Y2O3-doped ZrO2 coatings tended to decrease with increasing amounts of Y2O3 as shown in Fig.1. The thermal conductivity can be usually reduced by decreasing the mean free path due to the phonon scattering at pores or defects in the coatings.














Figure 1 Thermal conductivity and heat capacity of ZrO2-Y2O3 coatings by EB-PVD.

References:

[1] B.K.Jang, J.G. Sun, S.W. Kim, Y.S. Oh and H.T. Kim, Surf. Coat. Technol.207 (2012) 177.
[2] U. Schulz, K. Fritscher, A. E. Stahl, Surf. Coat. Technol. 203 (2008) 449.
Acknowledgements :