Effects of High Temperature Treatment on Thermal Cyclic Behavior of Thermal Barrier Coatings

Abstract

Ni3Al based alloy IC10 has been developed for turbine blades and vanes of advanced aero-engines and other high temperature structural components. Conventional two-layered structure thermal barrier coatings (TBCs) were produced by EB-PVD onto Ni-based superalloy. The thickness of bond coat and top coat was approximately 60μm and 120μm, respectively. After thermal barrier coatings were produced, it was heated at 1523K for 2hs, 6hs, 14hs and 20hs under 1×10-2Pa, respectively. After heat treatment was done, the thermal cyclic test was carried out by exposure to air at 1373K for 0.5h, and then cooled to room temperature within 5 minutes by forced air cooling. Scanning electron microscopy (SEM) was employed to study the microstructure of the coatings. After thermal cycled in air at 1373K for TBCs without heat treatment at 1523K, its lifetime is about 810 hours. After 760hs thermal cycles, the spallation occurred on the TBCs that the heat treatment was treated at 1523K for 2hs. The lifetime of TBCs, which the heat treatment was treated at 1523K for 6hs, was 710hs. The lifetime of TBCs, which the heat treatment was treated at 1523K for 14hs and 20hs, was 600hs and 560hs, respectively. The results showed that, with the increasing of the time of heat treatment, the weight gain increased evidently during thermal cycled. The results showed that heat treatment at 1523K affect the lifetime of TBCs during thermal cyclic evidently.