Influence of particle shape on erosion behavior of EB-PVD thermal barrier coatings

Abstract

In a thermal barrier coating (TBC) system with a complicated structure and a demanding service environment, erosion is a common failure mode. The influence of particle shape on erosion failure of electron beam physical vapor deposition (EB-PVD) TBCs was investigated using the finite element method in this study. There were two types of particles considered: ellipsoidal and spherical. To describe the particle shape, the geometric parameter long-to-short axis ratio λ was introduced. There were also two cases for ellipsoidal particles: long-axis erosion and short-axis erosion. The effect of particle velocity and erosion angle was taken into account. The results show that the shape of the erosion particle affects the maximum erosion depth, rebound velocity, and maximum residual stress for the same initial kinetic energy. In general, the ceramic layer erosion depth, rebound velocity, and interfacial stress S22 for ellipsoidal short-axis erosion are close to those for spherical erosion. The maximum erosion depth of the ceramic layer, rebound velocity, and interfacial residual stress S22 for ellipsoidal long-axis erosion, on the other hand, are significantly larger than those for the other two types of erosion, and these results for the long-short axis ratio of 3 are significantly larger than those for the long-short axis ratios of 2 and 3/2. The theoretical analytical model was used to validate the reliability of the finite element results. The findings indicate that the influence of erosion particle shape must be considered when studying the erosion failure mechanism of EB-PVD TBC.