| Abstract: | Thermal barrier coatings (TBCs) are being widely used in the high temperature components of gas turbine to protect the metal from high temperature damage and prolong the service life of gas turbine. The preparation process of TBCs is complex, and many control parameters will affect the microstructure of TBCs. Inhomogeneous microstructure changes caused by defects (such as cracks, erosion and corrosion pits) will occur under tough service conditions. In order to study the effect of the microstructure change on the thermal insulation and failure mechanism, it is necessary to construct the microstructure of TBCs under various working conditions. In this work, a new numerical pore-crack-particle microstructure reconstruction method (PCPMR) for porous media is proposed and used to reconstruct the three-dimensional (3D) microstructure of TBCs. In this method, characteristic parameters were extracted from the scanning electron microscope (SEM) images and the shape constraint factors of defects and the crack deformation rate as well as the particle deformation rate are introduced to control the morphologies of defects in porous TBCs. Then coatings with pores after preparation and coatings with defects during long-term services were reconstructed respectively. The features of coating microstructures reconstructed by this method are in good agreement with the real model obtained by SEM images. At the same time, the effective thermal conductivity of the coating with different porosities and segmentation cracks as well as the temperature distribution of the coating surface under different crack scales were analyzed in the reconstructed 3D TBCs samples. The calculated results are in good agreement with the measured data in the published literatures, which justify the reliability of the proposed PCPMR method. |
