The Effects of Yttrium on the Tensile and Creep Behavior of Thermally Grown Oxide at High Temperature

2006 ◽  
Author(s):  
G. D. Ko ◽  
S. K. Sun ◽  
K. J. Kang
Keyword(s):  
High Temperature ◽  
Mechanical Behavior ◽  
Thermal Barrier Coating ◽  
Creep Behavior ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
Different Levels ◽  
Thermally Grown

Recently, It has been revealed that TGO(thermally grown oxide) plays important roles on durability of TBC(thermal barrier coating) systems. In this work, Fecralloy foils were chosen as the substrates which form TGO on the surface at high temperature and the tensile and creep experiments were performed with the thick foils 100 μm at 1200°C. During the experiments the load, displacement and the TGO thickness were monitored in-situ. The effect of Yttrium on the mechanical behavior was investigated using the specimens with two different levels of the concentration. As the results, it was found that Yttrium enhances the strength of TGO as well as that of the substrate at the high temperature.

Modeling Thermally Grown Oxides in Thermal Barrier Coatings Using Koch Fractal

2019 ◽  
Author(s):  
Peter Warren ◽  
Sandip Haldar ◽  
Seetha Raghavan ◽  
Ranajay Ghosh
Keyword(s):  
Thermal Barrier Coating ◽  
Critical Role ◽  
Thermally Grown Oxide ◽  
Stress Generation ◽  
Interfacial Region ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Barrier Coating ◽  
Koch Fractal ◽  
Thermally Grown

Abstract Growth of the Thermally Grown Oxide (TGO) between the bond coat and thermal barrier coating (TBC) during service is one of the most common causes of failure within thermal barrier coating (TBC) systems. Initially this oxide will provide protection from oxidation for the substrate, but stress build up will contribute to delamination of the topcoat. Research has been carried out over the stresses caused by this TGO growth, and how to best mitigate these induced stresses. The interface topography plays a critical role for air plasma sprayed (APS) TBCs in development of stress profiles across the TGO/TBC interface [1, 2]. The APS TBCs fail by cracking in the TBC close to the TGO-TBC interface. Most models treat TGO as a sinusoidal wavelength interface. However, most TGO surfaces have been experimentally observed to have fractal like patterns at the interfacial region of the bondcoat and topcoat. Fractals provide us a better understanding of interactions at rough interfaces between two materials adhered to one another. In this work, we model the topography of the TGO using a Koch fractal. We find the geometry selected to model the TGO layer has a direct effect on the stress generation and creep strain during simulation.

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