Spark plasma sintering of damage tolerant and machinable YAM ceramics

Qian Wang,Qing Huang,Chunfeng Hu,Yoshio Sakka,Shu Cai,Haibin Zhang,Salvatore Grasso

doi:10.1007/s40145-013-0061-1

Abstract

Single-phase Y4Al2O9 (YAM) powders were synthesized via solid-state reaction starting from nano-sized Al2O3 and Y2O3. Fully dense (99.5%) bulk YAM ceramics were consolidated by spark plasma sintering (SPS) at 1800 ℃. We demonstrated the excellent damage tolerance and good machinability of YAM ceramics. Such properties are attributed to the easy slipping along the weakly bonded crystallographic planes, resulting in multiple energy dissipation mechanisms such as transgranular fracture, shear slipping and localized grain crushing.

Highlights

In the Al2O3–Y2O3 phase diagram, three intermediate compounds exist: (i) Y3Al5O12 (YAG) with cubic yttrium aluminum garnet structure, (ii) YAlO3 (YAP) with orthorhombic yttrium aluminum perovskite or hexagonal structure, and (iii) Y4Al2O9 (YAM) with monoclinic structure [1]
No electron migration occurred in the reaction process; the reaction was mainly driven by the mutual diffusion of Al3+ and Y3+ ions
Single-phase Y4Al2O9 (YAM) powders were successfully synthesized by a solid-state reaction carried out at 1650 °C for 30 h starting from nano-sized Al2O3 and Y2O3 particles

Summary

Introduction

In the Al2O3–Y2O3 phase diagram, three intermediate compounds exist: (i) Y3Al5O12 (YAG) with cubic yttrium aluminum garnet structure, (ii) YAlO3 (YAP) with orthorhombic yttrium aluminum perovskite or hexagonal structure, and (iii) Y4Al2O9 (YAM) with monoclinic structure [1]. YAG has been widely investigated for a wide range of applications, including rare-earth doped phosphors [2,3,4,5,6] The luminescence properties of rare-earth doped YAM have been widely investigated. The thermal stability and phase transformation of YAM at high temperature attract considerable research attention as well [20,21,22,23,24]. YAM might have some potential applications even as high-temperature oxidation/ thermal barrier coatings [25]. Zhan et al [26] have shown that the lattice thermal conductivity of YAM is as low as 1.10 W/(m·K) on the basis of the first-principles calculation, and experimental results confirme a very low thermal conductivity of 1.56 W/(m·K) at 1000 °C

Methods

Results

Conclusion