Thermal and mechanical properties of sintered bodies and EB-PVD layers of Y 2O 3 added Gd 2Zr 2O 7 ceramics for thermal barrier coatings

Abstract

In this study, the sintered bodies and EB-PVD coatings of gadolinium zirconate (Gd 2Zr 2O 7) ceramics with thermal and elastic resistance are prepared by the addition of yttrium oxide (Y 2O 3) to the composition of Gd 2Zr 2O 7 for thermal barrier coatings. XRD analysis reveals that the Y 2O 3-doped Gd 2Zr 2O 7 thermal barrier material has a thermally stable pyrochlore structure. The Y 2O 3-doped Gd 2Zr 2O 7 shows lower thermal conductivity than Y 2O 3-doped stabilized zirconia (YSZ), from 2.12 W/m K to 0.82–1.32 W/m K, and greater hardness than pure Gd 2Zr 2O 7, from 6 GPa to 10 GPa as measured by Vickers indentation and more than 20 GPa by nano-indentation, mainly owing to changes in the microstructure. The indentation stress–strain curves and load–penetration depth curves obtained by Hertzian and nano-indentation measurements indicate that the behavior of the curve is crucially influenced by the addition of Y 2O 3 to the pure Gd 2Zr 2O 7. The results suggest that Y 2O 3-doped Gd 2Zr 2O 7 may be expected to yield hardness and thermal insulation properties superior to those of commercial YSZ coatings for thermal barrier coatings on high temperature alloys.