Assessment of the Characteristic of Thermal Barrier Coating Applied to Gas Turbine Blade by Thermo-Gradient Mechanical Fatigue Test

A gas turbine blade is under centrifugal force owing to high speed rotation and is under thermal fatigue owing to hot gas during the DSS (Daily Start and Stop) operation. Also, thermal barrier coating (TBC) is applied to protect a blade of gas turbine system from high temperature gas and to lower the surface temperature of the blade. The failure of TBC is directly connected with the failure of the blade because of excessive local degradation at the location of TBC failure. In this study, thermo-gradient mechanical fatigue (TGMF) tests by a furnace which can control heat flux directly have been performed to evaluate the thermal fatigue characteristics between a coated specimen and an uncoated specimen. Also, the failure mechanism of the TBC under TGMF condition has been estimated by micro-structure analysis at the cross-section of fractured specimen.