Finite Element Analysis Of The Thermal Residual Stress In EB-PVD Thermal Barrier Coatings

Thermal barrier coatings are used universally in many industry areas, for the following purpose: protecting the metal substrates, enhancing the efficiency of system, reducing the exhaust of fuel, this is of much importance in present when the lack of fuel and energe expands widely around the world.But the gas turbine components were often damaged due to the premature spallation of the thermal barrier coatings, naturally the widely use of thermal barrier coatings was limited in the aerospace industry. So deep comprehension of the damage mechanism of thermal barrier coatings, enhance the working life and reliability of thermal barrier coatings, lengthening the interval of engine repair, reducing the cost of engine repair, are of serious importance.There are many kinds of thermal barrier coatings. This paper focused on the EB-PVD thermal barrier coatings. The emphases were placed on the instant response of EB-PVD thermal barrier coatings under the thermal cycling loading.Under the thermal cycling loading, EB-PVD thermal barrier coatings have several damage mechanisms, of them the major mechanism is as following: the imperfections or the undulation of the interface between the bond coat, the thermal grown oxides (TGO) and the top layer (TBC), result in the emerge of stresses (which are perpendicular to the interface of TBC/TGO) in the area of thermal barrier coat (TBC) and bond coat (BC) which is near to the TGO. These stresses driven the delamination in this area to expand along the interface, until the final spallation occurs.By the using of ANSYS commercial software, the analyses of EB-PVD TBC system were carried on in this paper. The system includes the substrate, NiCoCrAlY bond coat, TGO and EB-PVD TBC. Firstly the transient responses (including the temperature, stress and strain field) with time of the coating system with TGO isolated islands were calculated; then the effects of different distributions (including distance from TGO layer, Number and different radius) of TGO isolated islands in the coating system on the stresses distribution and reliability of the thermal barrier coating system were calculated and analyzed in detail. The analysis results can give some reference to the quality controlling of thermal barrier coating system.Basing on the long cylindrical sample of burner-rig test (BRT),by the using of parametric modeling, the effect of different interface morphology on the residual stress and the reliability of the TBCs were studied. After analyses of the results of these calculations, conclusions on the optimization of interface morphology emerged. These conclusions can benefit the manufacture of TBCs with more reliability.