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Fatigue Lifetime Approximation Based On Quantitative Microstructural Analysis For Air Plasma Sprayed Thermal Barrier Coatings, Carmen Bargraser
Fatigue Lifetime Approximation Based On Quantitative Microstructural Analysis For Air Plasma Sprayed Thermal Barrier Coatings, Carmen Bargraser
Electronic Theses and Dissertations
The durability of thermal barrier coatings (TBCs) affects the life of the hot section engine components on which they are applied. Fatigue is the general failure mechanism for such components and is responsible for most unexpected failures; therefore it is desirable to develop lifetime approximation models to ensure reliability and durability. In this study, we first examined the microstructural degradation of air plasma sprayed ZrO2-8wt.%Y2O3 TBCs with a low-pressure plasma sprayed CoNiCrAlY bond coat on an IN 738LC superalloy substrate. The durability of TBCs were assessed through furnace thermal cyclic tests carried out in air at 1100°C with a 1-, …
Effects Of Thermo-Mechanical Loading From In-Situ Studies Of Eb-Pvd Thermal Barrier Coatings, Melan N. Jansz
Effects Of Thermo-Mechanical Loading From In-Situ Studies Of Eb-Pvd Thermal Barrier Coatings, Melan N. Jansz
Electronic Theses and Dissertations
The thermo-mechanical effects on the strain evolution within an EB-PVD thermal barrier coating (TBC) is presented in this work using in-situ characterization. Synchrotron X-ray diffraction at sector 1-ID at the Argonne National Laboratory provided both qualitative and quantitative in-situ data on the strain evolution under a thermal cycle with mechanical loading. The results show that at a critical combination of temperature and load, the stress in the thermally grown oxide (TGO) layer in the TBC reaches a tensile region. These significant findings enhance existing literature showing purely compressive strains within the TGO where mechanical loads have been neglected. The results …
Correlating Microstructural Development And Failure Mechanisms To Photo Stimulated Luminescence Spectroscopy And Electrochemical Impedance Spectroscopy In Thermal Barrier Coatings, Balaji Jayaraj
Electronic Theses and Dissertations
Thermal barrier coatings (TBCs) are widely used for thermal protection of hot section components in turbines for propulsion and power generation. Applications of TBCs based on a clearer understanding of failure mechanisms can help increase the performance and life-cycle cost of advanced gas turbine engines. Development and refinement of robust nondestructive evaluation techniques can also enhance the reliability, availability and maintainability of hot section components in gas turbines engines. In this work, degradation of TBCs was non-destructively examined by photostimulated luminescence spectroscopy (PSLS) and electrochemical impedance spectroscopy (EIS) as a function of furnace thermal cycling carried out in air with …
Evolution Of Microstructure And Residual Stress In Disc-Shape Eb-Pvd Thermal Barrier Coatings And Temperature Profile Of High Pressure Turbine Blade, Sriparna Mukherjee
Evolution Of Microstructure And Residual Stress In Disc-Shape Eb-Pvd Thermal Barrier Coatings And Temperature Profile Of High Pressure Turbine Blade, Sriparna Mukherjee
Electronic Theses and Dissertations
A detailed understanding of failure mechanisms in thermal barrier coatings (TBCs) can help develop reliable and durable TBCs for advanced gas turbine engines. One of the characteristics of failure in electron beam physical vapor deposited (EB-PVD) TBCs is the development of instability, named rumpling, at the interface between (Ni, Pt)Al bond coat and thermally grown oxide (TGO). In this study, thermal cycling at 1100°C with 1 hr dwell time was carried out on 25.4mm disc specimens of TBCs that consisted of EB-PVD coated ZrO2-7wt. %Y2O3, (Pt,Ni)Al bond coat, and CMSX-4 Ni-based superalloy. At specific fraction of lifetime, TBCs were examined …