Influence of elastic properties of substrate and coating on the residual stress distribution of FGM coatings

摘要

The major problem in thermal barrier coatings (TBC) applied to gas turbine components is the spallation of ceramic coating under thermal cycling processes. In order to prevent spallation and improve the thermo-mechanical behaviour of the TBC. graded ceramic coatings can be fabricated. Therefore. a detailed study of the optimization of the gradient profile is necessary in respect to thermal stress relief. In this paper a numerical model of elastic thermal stress distribution within a multilayered system which consists of a Functionally Gradient Material (FGM), is presented. The structure of the graded coating system is made of a ceramic layer and a metallic layer, where between them there is an interlayer which is a graded composite made of the metal (NiCr-alloy) and the ceramic (ZrO{sub}2Y{sub}2O{sub}3). The effects of elastic modulus of the alloy substrate, the graded interlayer thickness and ceramic layer porosity on residual stress distribution were studied for the ease of a graded TBC using a linear compositional profile for the FGM.