Characterization of rupture and fatigue resistance of TBC superalloy for combustion liners

High-temperature, high-cycle fatigue and accelerated creep properties of thermal barrier coated (TBC) Superni C263 alloy used as a candidate material in combustor liners of aero engines are highlighted in this paper. An acoustic emission technique has been utilised to detect the ductile-brittle transition temperature of the bond coat. Results revealed that the ductile-to-brittle transition temperature (DBTT) of this bond coat is around 650 °C, which is in close proximity to the value reported for CoCrAlY type of bond coat. The endurance limit in fatigue and the life of TBC coated composite under accelerated creep conditions are substantially higher than those of the substrate material. Fractographic features at high stresses under fatigue was intergranular cleavage whereas those at low stresses were transgranular and ductile in nature. Delamination of the bond coat and spallation of the TBC at high stresses during fatigue was evident. It is recommended that these TBCs should not be put into use above 800 °C for more than 1000 h of continuous operation as the strength of the TBC superalloy drops to negligible levels.