%0 Journal Article
%T Investigation on the Interface Characteristics of the Thermal Barrier Coating System through Flat Cylindrical Indenters
%A Shifeng Wen
%A Xiaohu Zeng
%A Gongnan Xie
%J Advances in Mechanical Engineering
%D 2014
%I SAGE Publications
%R 10.1155/2014/654096
%X Thermal barrier coating (TBC) systems are highly advanced material systems and usually applied to insulate components from large and prolonged heat loads by utilizing thermally insulating materials. In this study, the characteristics of the interface of thermal barrier coating systems have been simulated by the finite-element method (FEM). The emphasis was put on the stress distribution at the interface which is beneath the indenter. The effect of the interface roughness, the thermally grown oxide (TGO) layer＊s thickness, and the modulus ratio ( ) of the thin film with the substrate has been considered. Finite-element results showed that the influences of the interface roughness and the TGO layer＊s thickness on stress distribution were important. At the same time, the residual stress distribution has been investigated in detail. 1. Introduction Thermal barrier coating (TBC) systems are widely used in modern gas turbines and jet engines. They protect materials and allow hot gas temperatures to increase the efficiency of the engine [1每4]. Their local failure in hot spots with severe impacts on the structural integrity of the engine has been prevented during operation. Therefore, the failure of TBC systems should be sufficiently understood. Experimental observations showed that the failure of TBC system is very complex and mostly affected by a superposition of different mechanisms. For instance, the initiation of cracks very close to the interface between the TBC and the bond coat (BC) seemed to be explained well by the residual stress calculations made by Chang et al. [5] and others [6每9], but their propagation was not similar with the result observed through experiment. Meanwhile, numerous models based upon different conceptions have been proposed, which might qualitatively explain how cracks propagated [6, 10每12]. All models considered oxidation at the rough interface between TBC and BC and the phenomena resulting from the redistribution of residual stresses induced by volume increasing or morphological instability of the thermally grown oxide (TGO) layer [12每17] as the driving force of crack propagation. However, all models lacked quantitative verification. It is very interesting to apply the indentation technology to thin film/substrate (especially TBC) systems. Now many models to determine the adhesion strength have been presented [18每20]. It is important to analyze the stress characteristics of thin film/substrate systems. For example, the stress distribution of the layers has been studied by Njiwa and von Stebut [21] and Diao [22] with the boundary
%U http://www.hindawi.com/journals/ame/2014/654096/