Thermo-Mechanical Buckling Failure of Thermal Barrier Coatings with Arbitrary Delamination Location W. G. Mao 1,2 , C. Y. Dai 1,2 ,Y. C. Zhou 1,2,∗ and X. H. Yu 1,2 1 Faculty of Materials & Optoelectronics Physics, Xiangtan University, Hunan 411 105, China 2 Key Laboratory for Advanced Materials and Rheological Properties of Ministry of Education, Xiangtan University, Xiangtan, Hunan 411 105, China ∗ zhouyc@xtu.edu.cn Abstract A one-dimensional interface delamination model is introduced to analyze the thermo-mechanical buck- ling characteristic of Thermal Barrier Coatings (TBCs) system with arbitrary across-the-width delami- nation. Equilibrium equations, stability equations and characteristic equation governing buckling under external thermal and mechanical loadings are derived on the basis of the first order shear deformation theory and the State Space Method (SSM). Different types of thermal loading and temperature gradi- ent across the thickness are considered, and the thermo-mechanical buckling loadings are accurately obtained. Finally the effects of Thermal Barrier Coatings (TBCs) system aspect ratio, relative thickness, delamination location and temperature gradient on thermo-mechanical buckling failure of TBCs are all discussed. Keywords: Thermal Barrier Coatings, Thermo-Mechanical Buckling Failure, Delamination 1 Introduction Thermal Barrier Coatings (TBCs) are commonly used as protective coatings for advanced power engi- neering applications to improve performance and thermal efficiency [1–4] . It consists of a ceramic coating, a Thermally Grown Oxide (TGO) that thickens as the system cycles, bond coat that provides the oxida- tion resistance, and substrate. The function of TBC is that lowering the temperature of substrate prolongs the life of the devices. However, in its service, oxidation phenomenon occurs between the ceramic coat- ing and bond coat in an aggressive environment. The oxidation film (mainly Al 2 O 3 ) forms and thickens with respect to thermal cycling, which will result in 1 interface delamination, crack nucleation, propaga- tion and coalescence. On the other hand, due to materials mismatch and temperature gradient in TBCs, the stress in the ceramic coating is compressive on cooling to the ambient temperature. Furthermore, the residual stress accumulates with thermal cycling [5–7] . Eventually, it will result in the spalling or buck- ling failure of the ceramic coating. Gell et al. had studied that the spallation life of TBCs on a MCrAlY bond coated Ni-base superalloy substrate deposited under the optimized processing conditions. They found that the buckling spallation is the failure of TBCs occurring within the ceramic top coat under thermal cyclic test, as shown in Fig. 1 [8] . Hutchinson et al. had analyzed that the influence of prototyp- ical imperfections on the nucleation and propagation stages of delaminations of compressed thin films. Energy release rates for separations that develop from imperfections had been calculated. They found ∗ Corresponding author ADVANCES IN VIBRATION ENGINEERING, 6(2) 2007 © KRISHTEL eMAGING SOLUTIONS PRIVATE LIMITED