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In our previous work, anisotropic chemical bonding, low shear deformation resistance, damage tolerance ability, low thermal conductivity, and moderate thermal expansion coefficient of Y4Al2O9 (YAM) were predicted. In this work, phase-pure YAM powders were synthesized by solid-state reaction between Y2O3 and Al2O3 and bulk YAM ceramics were prepared by hot-pressing method. Lattice parameters and a new set of X-ray powder diffraction data were obtained by Rietveld refinement. The mechanical and thermal properties of dense YAM ceramics were investigated. The measured elastic moduli are close to the theoretical predicted values and the stiffness can be maintained up to 1400 ℃. The flexural strength and fracture toughness are 252.1±7.3 MPa and 3.36±0.20 MPa·m1/2, respectively. Damage tolerance of YAM was also experimentally proved. The measured average linear thermal expansion coefficient (TEC) of YAM is 7.37×10-6 K-1, which is very close to the theoretical predicted value. Using high-temperature X-ray diffraction (XRD) analysis, volumetric TEC is determined (23.37±1.61)×10-6 K-1 and the anisotropic TEC are αa = 7.34×10-6 K-1, αb = 7.54×10-6 K-1, and αc = 7.61×10-6 K-1.


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Preparation, mechanical, and thermal properties of a promising thermal barrier material: Y4Al2O9

Show Author's information Yanchun ZHOU( )Xinpo LUHuimin XIANGZhihai FENG
Science and Technology of Advanced Functional Composite Laboratory, Aerospace Research Institute of Materials and Processing Technology, No. 1 South Dahongmen Road, Beijing 100076, China

Abstract

In our previous work, anisotropic chemical bonding, low shear deformation resistance, damage tolerance ability, low thermal conductivity, and moderate thermal expansion coefficient of Y4Al2O9 (YAM) were predicted. In this work, phase-pure YAM powders were synthesized by solid-state reaction between Y2O3 and Al2O3 and bulk YAM ceramics were prepared by hot-pressing method. Lattice parameters and a new set of X-ray powder diffraction data were obtained by Rietveld refinement. The mechanical and thermal properties of dense YAM ceramics were investigated. The measured elastic moduli are close to the theoretical predicted values and the stiffness can be maintained up to 1400 ℃. The flexural strength and fracture toughness are 252.1±7.3 MPa and 3.36±0.20 MPa·m1/2, respectively. Damage tolerance of YAM was also experimentally proved. The measured average linear thermal expansion coefficient (TEC) of YAM is 7.37×10-6 K-1, which is very close to the theoretical predicted value. Using high-temperature X-ray diffraction (XRD) analysis, volumetric TEC is determined (23.37±1.61)×10-6 K-1 and the anisotropic TEC are αa = 7.34×10-6 K-1, αb = 7.54×10-6 K-1, and αc = 7.61×10-6 K-1.

Keywords: mechanical properties, thermal expansion, damage tolerance, Y4Al2O9, X-ray diffraction (XRD) pattern

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Publication history

Received: 26 January 2015
Accepted: 02 February 2015
Published: 30 May 2015
Issue date: June 2015

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© The author(s) 2015

Acknowledgements

This work was supported by the National Outstanding Young Scientist Foundation for Y. C. Zhou under Grant No. 59925208, and the National Natural Science Foundation of China under Grant Nos. 50832008 and U1435206.

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Open Access: This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.

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