Fatigue and creep damage resistance of a thermal barrier coated superalloy for combustor liners in aero turbines

Fatigue testing of thermal barrier coated (TBC), bond coated only and bare Superni C263 superalloy was conducted at 800ºC in air. Fatigue results reveal that the endurance limits for the TBC and bond coated substrate was substantially higher than that of the base alloy, while the
opposite was found for high stress, low cyclic life times. It appears that the increase in endurance limit for the TBC and bond coated superalloy
is due to load shifting to the bond coat, and the premature failure for these two materials is possibly due to high stress crack imitation/growth
in the TBC/bond coat layers. In addition to fatigue, accelerated creep properties of thermal barrier coated (TBC) Superni C263 were evaluated.
Creep results reveal that the life of the TBC composite under accelerated creep condition is substantially high compared to that of the bare
substrate. The mode of fracture in the substrate at very high stresses was transgranular whereas that at low stresses was intergranular.
Delamination of bond coat, oxidation of the substrate and spallation of the ceramic layer were evident at very high stress. It was evident
that the substrate has negligible estimated rupture strength after 10,000 hours of service exposure.