Influence And Analysis Of TGO Growth On Failure Mechanism Of Thermal Barrier Coating System

Thermal barrier coatings(TBC,Thermal Barrier Coatings)are widely used on the hot-end parts of aviation power plants because of their high temperature resistance,corrosion resistance and oxidation resistance.Oxidative growth occurs to form a thermal growth oxide layer(TGO,Thermal Growth Oxide).TGO will generate growth stress in it,which is one of the main factors leading to the failure of thermal barrier coatings.Based on ABAQUS,this paper simulated the dynamic growth process of TGO,and analyzed the effects of stress and other factors on the failure of thermal barrier coatings.The main tasks are as follows:(1)It is difficult to simulate the dynamic continuous growth process of TGO with time.Based on the development of ABAQUS software,this paper establishes a UMAT subroutine.The material constitutive function is written in Fortran language to simulate the continuous growth process of TGO during high temperature.(2)Use the established TGO model to numerically simulate the dynamic growth process during thermal cycling,analyze the displacement instability of TGO growth,and compare the research results with Kalsson’s classic method.The results show that when TGO thickness is greater than 1μm,Karlsson’s method cannot converge and stop simulating TGO growth.Compared with UMAT method,it can be applied to thicker TGO growth simulation with certain advantages.(3)Study the TGO growth stress during thermal cycling.The distributions of tangential and longitudinal stresses in TGO and their changes are analyzed.In addition,the mechanical parameters of the thermal barrier coating itself have a great influence on the TGO growth process.The effects of plastic yield,temperature constant of the elastic constant,and temperature dependence of the yield strength on the growth process of TGO are analyzed.