A Double Layer Thermal Barrier Concept Made of Gadolinium Zirconate and YSZ

Partially yttria stabilised zirconia (YSZ) approaches limits of performance in long-term operation at 1200°C as a thermal barrier coating (TBC). For the next generation of TBCs, higher temperature capability and longer lifetime of the coatings are essential to boost efficiency of gas turbine engines. In this work, gadolinium zirconate (Gd₂Zr₂O₇) (GZO)/YSZ double ceramic layer TBCs are presented enabling to withstand higher temperatures. Processing of the GZO layers by atmospheric plasma spraying with TriplexPro^TM spray torch, which is complicated due to the different vapour pressures of the feedstock constituents, is described. Furthermore, the influence of varied GZO microstructures in terms of porosity on lifetime and failure modes of the double layers tested at surface temperature of 1400°C is reported.