The Correlation Of Residual Stress In TGO With Interface Failure Of Thermal Barrier Coatings

Thermal barrier coatings (TBCs) have been widely used in the field of hightemperature thermal protection, especially aircraft turbine engine internal hightemperature parts due to the excellent heat insulation performance and oxidationresistance. TBCs has become a key technology to increase the temperature of theturbine engine. however in the actual service environment, because of intricatestructure of TBCs system and harsh operation conditions, and resulting in failure atlas, it is a serious security hidden danger in the process of flying aircraft engine，which greatly restrict the use of thermal barrier coating. The application of advancedNDT technology to monitor interface failure process and quantitative assessment ofthe thermal barrier coating interface damage has gradually become an importantmeans of the nondestructive evaluation and life prediction. This article, we have runout of fluorescence piezoelectric spectrum (PLPS) method to measure the differentstages of thermal oxidation in the process of high temperature thermal cycling ofthermal barrier coating TGO layer, residual stress and thermal barrier coatinginterface failure is studied and the relationship between stress evolution in oxidation(TGO) layer, the main research content is as follows:First, the PLPS method in the process of high temperature thermal cyclemeasurement TGO layer stress evolution law, found that the residual stress increased,stability, at the inflection point, again slowly decrease sharply four stages, stressPLPS method can be a very good measure the residual stress in the TGO.Second, Residual stress according to the experiment TGO involvement with theoxide layer interface damage evolution, the results show that through the stressvariation in the TGO can estimate the damage in the oxide layer, the early stage of theoxidation, residual stress is zero defect in the oxide layer; The shift to rapid decreasein stress, began to form the interface crack in TGO sample; When under stress reduceto1GPa, occur within the sample of interface crack; Stress less close to zero, oxidehas been completely destroyed, ceramic layer peeling. PLPS method is used tomeasure the TGO layer stress evolution law that can predict a good interface crackinitiation and propagation process, to assess the thermal barrier coating nondestructiveevaluation and prediction of its service life.Third, through statistical TBCs oxide stress appeared inflection point samplescorresponding to the thermal cycles, the interface of TBCs spalling failure when the critical thermal cycles, the Weibull distribution analysis, the results show that thedispersion eiko m=4.12, shows that the critical thermal cycling times of dispersion isbigger. Characteristics of cycle number N0=145, corresponding to the cumulativeprobability, said cycles of oxide layer damage standard, get thermal barrier coatings inthermal cycle interface damage under the condition of reliability assessment, thedispersion is bigger, show the poor reliability.