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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:

Y4Al2O9, X-ray diffraction (XRD) pattern, mechanical properties, thermal expansion, damage tolerance
Received: 26 January 2015 Accepted: 02 February 2015 Published: 30 May 2015 Issue date: June 2015
References(23)
[1]
Zhan X, Li Z, Liu B, et al. Theoretical prediction of elastic stiffness and minimum lattice thermal conductivity of Y3Al5O12, YAlO3 and Y4Al2O9. J Am Ceram Soc 2012, 95:1429-1434.
[2]
Zhou Y, Xiang H, Lu X, et al. Theoretical prediction on mechanical and thermal properties of a promising thermal barrier material: Y4Al2O9. J Adv Ceram 2015, .
[3]
Li Z, Liu B, Wang JM, et al. First-principle study of point defects in stoichiometric and nonstoichiometric Y4Al2O9. J Mater Sci Technol 2013, 29:1161-1165.
[4]
Mah T-I, Petry MD. Eutectic composition in the pseudobinary of Y4Al2O9 and Y2O3. J Am Ceram Soc 1992, 75:2006-2009.
[5]
Zhou X, Xu Z, Fan X, et al. Y4Al2O9 ceramics as a novel thermal barrier coating material for high temperature applications. Mater Lett 2014, 134:146-148.
[6]
Rietveld HM. Line profiles of neutron powder-diffraction peaks for structure refinement. Acta Cryst 1967, 22:151-152.
[7]
Rietveld HM. A profile refinement method for nuclear and magnetic structures. J Appl Cryst 1969, 2:65-71.
[8]
ASTM International. ASTM E1876-97 Standard test method for dynamic Young’s modulus, shear modulus, and Poisson’s ratio by impulse excitation of vibration. West Conshohocken, PA, 1998.
[9]
Roebben G, Bollen B, Brebels A, et al. Impulse excitation apparatus to measure resonant frequencies, elastic moduli, and internal friction at room and high temperature. Rev Sci Instrum 1997, 68:4511.
[10]
He L-F, Bao Y-W, Wang J-Y, et al. Mechanical and thermophysical properties of Zr–Al–Si–C ceramics. J Am Ceram Soc 2009, 92:445-451.
[11]
Yamane H, Shimada M, Hunter BA. High temperature neutron diffraction study of Y4Al2O9. J Solid State Chem 1998, 141:466-474.
[12]
Chen X-Q, Niu H, Li D, et al. Modeling hardness of polycrystalline materials and bulk metallic glasses. Intermetallics 2011, 19:1275-1281.
[13]
Bao YW, Hu CF, Zhou YC. Damage tolerance of nanolayer grained ceramic and quantitative estimation. Mater Sci Tech 2006, 22:227-230.
[14]
Zhou Y-C, Zhao C, Wang F, et al. Theoretical prediction and experimental investigation on the thermal and mechanical properties of bulk β-Yb2Si2O7. J Am Ceram Soc 2013, 96:3891-3900.
[15]
Sun Z, Zhou YC, Wang JY, et al. γ-Y2Si2O7, a machinable silicate ceramic: Mechanical properties and machinability. J Am Ceram Soc 2007, 90:2535-2541.
[16]
Zhou Y, Sun Z. Microstructure and mechanism of damage tolerance for Ti3SiC2 bulk ceramics. Mater Res Innov 1999, 2:360-363.
[17]
Barsoum MW, El-Raghy T, Ali M. Processing and characterization of Ti2AlC, Ti2AlN, and Ti2AlC0.5N0.5. Metall Mater Trans A 2000, 31:1857-1865.
[18]
Li F, Liu B, Wang J, et al. Hf3AlN: A novel layered ternary ceramic with excellent damage tolerance. J Am Ceram Soc 2010, 93:228-234.
[19]
Lin ZJ, Zhuo MJ, Li MS, et al. Synthesis and microstructure of layered-ternary Ti2AlN ceramic. Scripta Mater 2007, 56:1115-1118.
[20]
Wang XH, Zhou YC. Layered machinable and electrically conductive Ti2AlC and Ti3AlC2 ceramics: A review. J Mater Sci Technol 2010, 26:385-416.
[21]
Donnay JDH, Haker D. A new law of crystal morphology extending the law of Bravais. Am Mineral 1937, 22:446-447.
[22]
Wells AF. Crystal habit and internal structure. Phil Mag 1946, 37:184-199.
[23]
Berkovitch-Yellin Z. Toward an ab initio derivation of crystal morphology. J Am Chem Soc 1985, 107:8239-8253.
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Publication history

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

Copyright

© 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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