Abstract
A scanning electron microscope (SEM) image based direct finite element (FE) mesh reconstruction method is employed to reflect microstructure features of thermal barrier coatings (TBC). The creep-plastic assumption of thermally grown oxide (TGO) scale and metallic bond coat (BC) as well as the strength difference (SD) property of ceramic top coat (TC) are considered to simulate the mechanical behavior. A diffusion oxidation model considering oxygen consumption is proposed to characterize TGO growth. The oxidation simulation of TBC is carried out under the consideration of actual microstructure features. The results revealed that the interface defects increase the surface-area-to-volume ratio of BC exposed to oxygen anion. This leads to the non-uniform TGO growth, which has also been observed in experimental studies. The microstructures and mechanical behavior strongly affect stress evolution in TBC. The consideration of actual microstructure features and reasonable mechanical behaviors, including the creep-plastic behavior and SD property, is helpful for the accurate evaluation of interface stress.
Highlights
IntroductionThe thermal barrier coatings (TBC), consisting of the high temperature resistant ceramic top coat (TC), oxygen anion permeation resistant thermally grown oxide (TGO) scale, and metallic bond coat (BC) enable gas turbine to withstand super-high gas temperature and extreme oxidation-corrosion [1]
The thermal barrier coatings (TBC), consisting of the high temperature resistant ceramic top coat (TC), oxygen anion permeation resistant thermally grown oxide (TGO) scale, and metallic bond coat (BC) enable gas turbine to withstand super-high gas temperature and extreme oxidation-corrosion [1].It is one of the indispensable elements for hot-end components
The microstructures of TBC, including complex interface morphology and randomly distributed microdefects; The mechanical behavior, for instance, the creep and plastic deformation often occurs during service; Coatings 2018, 8, 338; doi:10.3390/coatings8100338
Summary
The thermal barrier coatings (TBC), consisting of the high temperature resistant ceramic top coat (TC), oxygen anion permeation resistant thermally grown oxide (TGO) scale, and metallic bond coat (BC) enable gas turbine to withstand super-high gas temperature and extreme oxidation-corrosion [1]. It is one of the indispensable elements for hot-end components. The microstructures of TBC, including complex interface morphology and randomly distributed microdefects; The mechanical behavior, for instance, the creep and plastic deformation often occurs during service; Coatings 2018, 8, 338; doi:10.3390/coatings8100338 www.mdpi.com/journal/coatings. The first challenge is how to represent such microstructures accurately in FE mesh
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