Thermal and mechanical properties of sintered bodies and EB-PVD layers of Y2O3 added Gd2Zr2O7 ceramics for thermal barrier coatings

Abstract

In this study, the sintered bodies and EB-PVD coatings of gadolinium zirconate (Gd2Zr2O2) ceramics with thermal and elastic resistance are prepared by the addition of yttrium oxide (Y2O3) to the composition of Gd2Zr2O2 for thermal barrier coatings. XRD analysis reveals that the Y2O3-doped Gd2Zr2O2 thermal barrier material has a thermally stable pyrochlore structure. The Y2O3-doped Gd2Zr2O2 shows lower thermal conductivity than Y2O3-doped stabilized zirconia (YSZ), from 2.12 W/m K to 0.82-1.32 W/m K, and greater hardness than pure Gd2Zr2O2, 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 Y2O3 to the pure Gd2Zr2. The results suggest that Y2O3-doped Gd2Zr2O2 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.