High temperature cycling behavior of novel thermal barrier coatings deposited by high enthalpy plasma torch

Hybrid water/argon-stabilized plasma (WSP-H) torch may be used for efficient deposition of coatings from various types of feedstocks, i.e. coarse dry powders, suspensions, and solutions. This study will present results of recent thermal cycling experiments of several novel thermal barrier coatings (TBCs) deposited by WSP-H torch on nickel-based superalloy. Coatings with different designs of microstructures deposited from suspensions, solutions or powders were successfully prepared and tested by conventional isothermal annealing and thermal cycling fatigue (TCF) tests. Coating with layered top-coat consisting of three sublayers: i) yttria stabilized zirconia (YSZ) deposited from solution, ii) gadolinium zirconate (GZO) deposited from suspension, and iii) optional yttrium aluminum garnet (YAG) overlayer deposited from suspension was tested also with advanced laser-rig setup exposing the TBC layer to very high temperature (>1500 °C) combined with considerable thermal gradient. Obtained results clearly show potential of WSP-H technology for novel TBC applications, where protection of large components or deposition of thick coatings is desirable.