“Multilayer thermal barrier coating (TBC) architectures utilizing rare earth doped YSZ and rare earth pyrochlores”

• Mutlilayer and nanolayer TBCs were fabricated using EB-PVD.
• Coatings were composed of alternating layers of t′ low-k and Gd2Zr2O7.
• Erosion and thermal conductivity results out-performed baseline materials.
• Thermal stability is strongly influenced by layer thickness.

To allow for increased gas turbine efficiencies, new insulating thermal barrier coatings (TBCs) must be developed to protect the underlying metallic components from higher operating temperatures. This work focused on using rare earth doped (Yb and Gd) yttria stabilized zirconia (t′ low-k) and Gd2Zr2O7 pyrochlores (GZO) combined with novel nanolayered and thick layered microstructures to enable operation beyond the 1200 °C stability limit of current 7 wt.% yttria stabilized zirconia (7YSZ) coatings. It was observed that the layered system can reduce the thermal conductivity by ~ 45% with respect to YSZ after 20 h of testing at 1316 °C. The erosion rate of GZO is shown to be an order to magnitude higher than YSZ and t′ low-k, but this can be reduced by almost 57% when utilizing a nanolayered structure. Lastly, the thermal instability of the layered system is investigated and thought is given to optimization of layer thickness.