Tailoring Periodic Vertical Cracks in Thermal Barrier Coatings Enabling High Strain Tolerance
Tailoring Periodic Vertical Cracks in Thermal Barrier Coatings Enabling High Strain Tolerance
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在热障涂层中定制周期性垂直裂纹，实现高应变容限
DOI：
10.3390/coatings11060720
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发表时间：
2021-06
期刊：
影响因子：
3.4
通讯作者：
Ghazanfar Mehboob;Tong Xu;Guang Li;Guanjun Yang;Adnan Tahir;M. Ragab;S. Hussain
中科院分区：
文献类型：
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作者：
Ghazanfar Mehboob;Tong Xu;Guang Li;Guanjun Yang;Adnan Tahir;M. Ragab;S. Hussain
寿命是热障涂层隔热功能的基本支撑。因此，延长寿命是开发下一代热障涂层的关键。对于这个目标，由垂直裂纹形成的柱状结构似乎是有意义的。然而，其内在机制尚不清楚。本工作详细研究了周期性垂直裂纹对开裂行为的影响，以定制高应变耐受热障涂层。建立了一个有限元模型，研究了基体与涂层之间的热失配应变对裂纹行为的影响。采用虚拟裂纹闭合技术描述裂纹在载荷作用下的扩展过程。研究发现，两条垂直裂纹（SVC）沿面内方向的沿着对热障涂层的应变容限有显著影响。结果表明，应变能释放率（SERR）和预裂纹尖端的应力不断增加的SVC的增加，这表明裂纹的驱动力增加。当SVC很小时，裂纹不扩展，而随着SVC的增加，裂纹继续扩展。可以通过减少SVC来防止裂纹的生长。找到了SVC的一个临界值，当SVC小于临界值时，SERR可以显著降低。因此，周期性裂纹的SVC可以被定制以获得具有高应变容限的热障涂层。
Lifetime is a basic support for the thermal insulation function of thermal barrier coatings (TBCs). Therefore, extending the life span is essential to develop next-generation TBCs. For this objective, the columnar structure formed by vertical cracks appears to make sense. However, the underlying mechanism is still unclear. This work scrutinizes the influence of periodic vertical cracks on cracking behavior in order to tailor high strain tolerant TBCs. A finite element model was evolved to explore the crack behavior influenced by thermal mismatch strain between substrate and coating. The virtual crack closure technique (VCCT) was used to describe the propagation of crack under load. It is found clearly that the space between two vertical cracks (short for SVC) along the in-plane direction has a noteworthy influence on the strain tolerance of TBCs. Results indicate that the strain energy release rate (SERR) and stresses at the pre-crack tip increase continuously with the increase of the SVC, suggesting that the driving force for cracks is increasing. The crack is not propagated when the SVC is very small, whereas the crack grows continuously with the increase of the SVC. The growth of a crack can be prevented by reducing the SVC. A critical value for the SVC was found. When the SVC is less than the critical value, the SERR can be dramatically reduced. Thus, the SVC of periodic cracks can be tailored to obtain TBCs with high strain tolerance.