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Thermal barrier coatings failure mechanism during the interfacial oxidation process under the interaction between interface by cohesive zone model and brittle fracture by phase-field
International Journal of Solids and Structures ( IF 3.6 ) Pub Date : 2020-12-31 , DOI: 10.1016/j.ijsolstr.2020.12.020
Q.Q. Zhou , L. Yang , C. Luo , F.W. Chen , Y.C. Zhou , Y.G. Wei

Failure of Thermal barrier coatings (TBCs) caused by interface oxidation directly determines the ultimate durability of TBCs. The interfacial delamination and brittle fracture will co-occur during the interface oxidation of the TBCs. To study the interaction between the two failure modes, we develop a thermodynamically-consistent coupling framework combining the phase-field model of the brittle fracture in the bulk material and the cohesive zone model of the pre-existing adhesive interface for TBCs. We divide the critical energy release into two parts to distinguish interface and bulk material failure. According to the variational principle, the phase-field crack evolution equation is obtained. Moreover, the other variables’ coupled constitutive and evolving equations are obtained through the dissipation inequality and balance equations. Models and experiments show interface oxidation of APS (air plasma spraying)-TBCs is tending to cracks in the valley of the TC (top coating)/TGO (thermally grown oxide) interface and the peak of the TGO/BC (bond coating) interface. The newly generated TGO will turn the crack at the TGO/BC interface peak into TGO inner crack and eventually lead to equidistant cracks in the TGO peak. Besides, by studying the interaction between cracks at two locations, we find that the TGO/BC interface cracks promote the TC/TGO interface crack initiation and inhibit its propagation. The TC/TGO interface crack very weakly promoted the TGO/BC interface cracks initiation and propagation. The framework present here provides excellent potential for modeling the oxidation failure process in TBCs.



中文翻译:

粘结区模型界面与相场脆性断裂相互作用下界面氧化过程中的热障涂层破坏机理

界面氧化导致的隔热涂层(TBC)失效直接决定了TBC的最终耐久性。在TBC的界面氧化过程中会同时发生界面分层和脆性断裂。为了研究两种失效模式之间的相互作用,我们开发了一种热力学一致的耦合框架,该框架结合了散装材料中脆性断裂的相场模型和TBCs先前存在的粘合剂界面的内聚区模型。我们将临界能量释放分为两部分,以区分界面和散装材料故障。根据变分原理,得到了相场裂纹发展方程。此外,通过耗散不等式和平衡方程可得到其他变量的耦合本构和演化方程。模型和实验表明,APS(空气等离子喷涂)-TBCs的界面氧化趋于在TC(顶部涂层)/ TGO(热生长氧化物)界面的谷和TGO / BC(粘结涂层)界面的峰部开裂。新生成的TGO将把TGO / BC界面峰处的裂纹转变为TGO内部裂纹,并最终导致TGO峰中的等距裂纹。此外,通过研究两个位置的裂纹之间的相互作用,我们发现TGO / BC界面裂纹促进了TC / TGO界面裂纹的萌生并抑制了裂纹的扩展。TC / TGO界面裂纹非常弱地促进了TGO / BC界面裂纹的萌生和扩展。此处介绍的框架为在TBC中模拟氧化失效过程提供了极好的潜力。

更新日期:2021-01-28
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