Local high temperature phenomena near the complex interfaces of thermal barrier coatings based on non-Fourier model

Abstract

Thermal barrier coatings (TBCs) consist of a metal substrate (Sub), a bond coat (BC), and a ceramic top coat (TC). The ceramic coating is a porous dielectric layer with a significant relaxation time that cannot be ignored. In high-temperature environments, an irregularly shaped thermally grown oxide layer (TGO) forms between the BC and the TC. Therefore, using non-Fourier model to describe the thermal contact process of TBCs with complex interface can get more accurate results. However, it is difficult to obtain the analytical solution of this model. This paper introduces a finite volume method based on unstructured meshes to address the non-Fourier heat transfer process in the complex interfaces of multilayer TBCs. The gradient reconstruction technique is employed to calculate the cell derivatives on the surface. The method's reliability is confirmed through a comparison with a two-dimensional analytical solution. The results indicate that the thermal wave travels at a limited speed within the TC layer. After passing through the interface, the thermal wave travels very fast within the BC and Sub layers, due to the influence of thermal wave reflection and superposition, obvious local high temperature will be formed near the interface. In addition, the effects of thermal conductivity, relaxation time and interface shapes on the non-Fourier heat conduction process of TBCs are also discussed. The results of this paper are useful for the structural design and failure mechanism research in TBCs.