Investigation of fatigue behavior of a thermal barrier coating system

ABSTRACTPhD DissertationINVESTIGATION OF FATIGUE BEHAVIOR OF A THERMALBARRIER COATING SYSTEMSerdar DALKILIÇAnadolu UniversityGraduate School of SciencesCivil Aviation ProgramSupervisor: Asst. Prof. Dr. A. Akile TANATMIŞ2007, 149 pagesIn this dissertation, fatigue behavior of a thermal barrier coating systemapplied to the turbine blades of gas turbine aero-engines is investigated. Anexperimental study on the isothermal high temperature low cycle fatigue (HT-LCF) properties of a thermal barrier coating system and the results of thisexperimental study is presented. Investigated TBC system consists of adirectionally solidified nickel based superalloy IN 100 DS substrate, a yttriapartially stabilized zirconia (YPSZ) ceramic top coat and a NiCoCrAlY metallicbond coat. Both layers are applied by Electron Beam Physical Vapor Deposition(EB-PVD) method. Damages on test specimens are investigated in terms ofmechanical stress, number of cycles, the effect of thermal barrier coating and timeat high temperature. The macro and microstructural changes in the specimens aredescribed by means of various characterization techniques such as ScanningElectron Microscope (SEM), Energy Dispersive X-ray Analysis (EDX), X-rayDiffraction (XRD), Optical Microscope (OM) and Infrared Imaging (IR) and bycomparison of previous studies in the literature.Keywords: Gas Turbine, Thermal Barrier Coating, Zirconium Oxide,NiCoCrAlY, Low Cycle Fatigueii