Analytical Modeling of Unsteady Aluminum Depletion in Thermal Barrier Coatings

Authors: BÜLENT YEŞİLATA

Abstract: The oxidation behavior of thermal barrier coatings (TBCs) in aircraft turbines is studied. A simple, unsteady and one-dimensional, diffusion model based on aluminum depletion from a bond-coat to form an oxide layer of Al_{2}O_{3} is introduced. The model is employed for a case study with currently available experimental data. The diffusion coefficient of the depleted aluminum in the alloy, the concentration profiles at different oxidation times, and the thickness of Al-depleted region are obtained. The results suggest that potential changes in the thermo-mechanical properties of the original alloy in the Al-depleted region may be partly responsible for the mechanical failure of TBC systems.

Keywords: Thermal oxidation, Thermal barrier coating, Aluminum depletion, Alumina, Diffusion coefficient.

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