Application of an Image-Based Model of the Elastic Modulus of Porous Thermal Barrier Coatings

Abstract

The elastic modulus of plasma-sprayed thermal barrier coatings (TBCs), which have been utilized for gas turbine engine components at elevated temperatures, has been investigated using a proposed model. The main purpose of this paper is to explore the alterations in porous TBC microstructure that lead to alterations in its mechanical properties, including elastic modulus. This paper investigates the effect of different types of defects, i.e., nonflat porosity, microcracks and interlamellar porosity, on the elastic modulus of porous TBC materials. The first part of this paper quantitively studies the microstructural characterization of plasma-sprayed TBCs by means of an image analysis approach. The second part of this paper predicts the elastic modulus of plasma-sprayed TBCs based on microstructural changes, i.e., defects. The volumetric fraction of different types of defects and their shapes and orientations are also taken into account. It is found that both microcracks and interlamellar porosity exhibit a crucial optimization on the elastic modulus of porous TBCs, while nonflat porosity shows a lesser effect on the elastic modulus. The predicted data of the proposed model show relatively good agreement with FEA model results and experimentally measured results. These simulation results could help to further the understanding of the impact of porous TBC microstructural alterations on elastic modulus.