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

摘要

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 2.12W/mK to 0.82–1.32W/mK, 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.