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Rare-earth tantalates and niobates (RE3TaO7 and RE3NbO7) have been considered as promising candidate thermal barrier coating (TBC) materials in next generation gas-turbine engines due to their ultra-low thermal conductivity and better thermal stability than yttria-stabilized zirconia (YSZ). However, the low Vickers hardness and toughness are the main shortcomings of RE3TaO7 and RE3NbO7 that limit their applications as TBC materials. To increase the hardness, high entropy (Y1/3Yb1/3Er1/3)3TaO7, (Y1/3Yb1/3Er1/3)3NbO7, and (Sm1/6Eu1/6Y1/6Yb1/6Lu1/6Er1/6)3(Nb1/2Ta1/2)O7 are designed and synthesized in this study. These high entropy ceramics exhibit high Vickers hardness (10.9-12.0 GPa), close thermal expansion coefficients to that of single-principal-component RE3TaO7 and RE3NbO7 (7.9×10-6-10.8×10-6-1 at room temperature), good phase stability, and good chemical compatibility with thermally grown Al2O3, which make them promising for applications as candidate TBC materials.


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High entropy defective fluorite structured rare-earth niobates and tantalates for thermal barrier applications

Show Author's information Zifan ZHAOa,bHeng CHENaHuimin XIANGaFu-Zhi DAIaXiaohui WANGcWei XUdKuang SUNdZhijian PENGb( )Yanchun ZHOUa( )
Science and Technology on Advanced Functional Composite Laboratory, Aerospace Research Institute of Materials & Processing Technology, Beijing 100076, China
School of Engineering and Technology, China University of Geosciences, Beijing 100083, China
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
Shanghai Chenhua Science and Technology Corporation Ltd., Shanghai 201804, China

Abstract

Rare-earth tantalates and niobates (RE3TaO7 and RE3NbO7) have been considered as promising candidate thermal barrier coating (TBC) materials in next generation gas-turbine engines due to their ultra-low thermal conductivity and better thermal stability than yttria-stabilized zirconia (YSZ). However, the low Vickers hardness and toughness are the main shortcomings of RE3TaO7 and RE3NbO7 that limit their applications as TBC materials. To increase the hardness, high entropy (Y1/3Yb1/3Er1/3)3TaO7, (Y1/3Yb1/3Er1/3)3NbO7, and (Sm1/6Eu1/6Y1/6Yb1/6Lu1/6Er1/6)3(Nb1/2Ta1/2)O7 are designed and synthesized in this study. These high entropy ceramics exhibit high Vickers hardness (10.9-12.0 GPa), close thermal expansion coefficients to that of single-principal-component RE3TaO7 and RE3NbO7 (7.9×10-6-10.8×10-6-1 at room temperature), good phase stability, and good chemical compatibility with thermally grown Al2O3, which make them promising for applications as candidate TBC materials.

Keywords:

high entropy ceramics, defective fluorite structure, rare-earth niobates/tantalates, thermal barrier coating material
Received: 22 January 2020 Revised: 14 February 2020 Accepted: 15 February 2020 Published: 05 June 2020 Issue date: June 2020
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Publication history
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Publication history

Received: 22 January 2020
Revised: 14 February 2020
Accepted: 15 February 2020
Published: 05 June 2020
Issue date: June 2020

Copyright

© The Author(s) 2020

Acknowledgements

This study was financially supported by the National Natural Science Foundation of China (Nos. 51672064 and 51972089).

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