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

Abstract

Abstract:In our previous work, anisotropic chemical bonding, low shear deformation resistance, damage tolerance ability, low thermal conductivity, and moderate thermal expansion coefficient of Y 4 Al 2 O 9 (YAM) were predicted. In this work, phase-pure YAM powders were synthesized by solid-state reaction between Y 2 O 3 and Al 2 O 3 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 ℃.

Theoretical prediction on mechanical and thermal properties of a promising thermal barrier material: Y4Al2O9

“…The Vickers hardness of Y 4 Al 2 O 9 is estimated to be 10.2 GPa, which is close to the experimental measured value of 11.02 GPa [43]. O 9 , the projection of atoms on (010) and (100) planes are shown in Fig.…”

“…Theoretical evaluation on TEC is quite a challenge for material scientists. Several approaches including quasi-harmonic approximation (QHA) [45], molecular dynamics (MD) [46], and chemical bond theory [37] [43], which is quite close to the theoretical one, demonstrating the reliability of the theoretical result. The behavior of thermal transportation at different temperature ranges is an important factor that needs to be considered when selecting an applicable TBC.…”

High-entropy (Nd0.2Sm0.2Eu0.2Y0.2Yb0.2)4Al2O9 with good high temperature stability, low thermal conductivity and anisotropic thermal expansivity

“…Moreover, the linear thermal expansion coefficients along three crystallographic directions (αa, αb, and αc) were also calculated in the same way. Table 3 shows the anisotropic thermal expansion coefficients (αa, αb, and αc) and volumetric thermal expansion coefficient (αV) of (Nd0.2Sm0.2Eu0.2Y0.2Yb0.2)4Al2O9 together with those of Y4Al2O9 [19]. Clearly, the volumetric thermal expansion coefficient (αV) of (Nd0.2Sm0.2Eu0.2Y0.2Yb0.2)4Al2O9 (24.40×10 −6 /K) is slightly higher than that of The spatial configuration of RE1-O polyhedra is shown in Fig.…”

“…There are several key requirements for selecting the top refractory oxides, including good tolerance to harsh environments, thermal expansion match with the interlayer and the substrate materials, good phase stability at high temperature, low thermal conductivity, and so on [12,15,16,17]. Particularly, cuspidine-type rare-earth aluminates RE4Al2O9 are a class of ceramics that have been considered as potential materials for EBCs of silicon-based ceramics owing to their high melting point, low Young's modulus, good damage tolerance, close thermal expansion coefficients to that of mullite, low thermal conductivity and good resistance to hot gas atmosphere [16,18,19,20,21]. However, one major weakness of RE4Al2O9 compounds for EBC application is the high-temperature phase transition with a sudden change in volume, which can lead to cracking of the coatings in thermal cycling [22,23,24,25].…”

Phase Composition, Thermal Conductivity, and Toughness of TiO2-Doped, Er2O3-Stabilized ZrO2 for Thermal Barrier Coating Applications

“…One is exploring high-temperature ceramics with excellent phase stability and low thermal conductivity. These ceramics [13][14][15][16][17][18]. However, by comprehensive investigations, these materials are found to have some undesirable properties, like poor fracture toughness and low thermal expansion coefficients, which affect their practical applications.…”