What is the suitable segmentation crack density for atmospheric plasma sprayed thick thermal barrier coatings with the improved thermal shock resistance?
What is the suitable segmentation crack density for atmospheric plasma sprayed thick thermal barrier coatings with the improved thermal shock resistance?
复制标题
对于具有改进的抗热震性能的大气等离子喷涂厚热障涂层，合适的分段裂纹密度是多少？
DOI：
10.1016/j.apsusc.2017.05.030
复制
发表时间：
2018
影响因子：
6.7
通讯作者：
Wang Y
中科院分区：
文献类型：
--
作者：
Wang L;Zhong X H;Shao F;Ni J X;Yang J S;Tao S Y;Wang Y
通过有限元模型对提高热震性能的厚热障涂层分段裂纹密度进行了优化和控制。基于大气等离子喷涂（APS）制备的ttbc各层电流性能参数的模拟结果与热冲击试验结果吻合较好。研究结果表明，过大或过小均不利于ttbc抗热震性能的提高。本文定量地揭示了这一客观规律。根据模拟和实验结果，适宜的分段裂纹密度为2.38 ~ 4.76条/mm，有利于提高材料的抗热震能力。结果表明，当分节裂纹密度约为4 mm−1时，喷射态ttbc具有较好的抗热震性能。应力强度因子（KI）和能量释放率（Jintegration）随分段裂纹长度的增加而增加。分段裂纹的存在会提高ttbc的应变容限。用分节裂纹长度定量表征了试样的应变容限。aps - ttbc的破坏机制可归结为ttbc顶涂层的分段裂纹扩展，顶涂层/TGO（热生长氧化物）界面水平裂纹的形成和扩展。计算了主分段裂纹的扩展速率，建立了ttbc在热循环过程中的寿命预测模型。提出了延长ttbc使用寿命的可能方法。
The optimization and control of the segmentation crack density (Ds) for the thick thermal barrier coatings (TTBCs) with the improved thermal shock resistance has been performed via finite element modeling. The simulation results based on the current property parameters of each layer of the TTBCs fabricated by atmospheric plasma spraying (APS) are well consistent with the experimental results of thermal shock test. The investigation results indicate that too large or too lowDswill be not beneficial to the improvement of the thermal shock resistance of the TTBCs. TheDsmust be located at a suitable range, and this paper has revealed the objective law quantitatively. Based on our simulation and experimental results, the appropriate segmentation crack density is in the range of 2.38–4.76 cracks/mm which will be beneficial to improve the thermal shock resistance ability. It has been found that the as-sprayed TTBCs exhibited superior thermal shock resistance when the segmentation crack density is about 4 mm−1. The stress intensity factor (KI) and energy release rate (Jintegration) will increase with the increasing of segmentation crack length. The existence of segmentation crack will improve the strain tolerance of TTBCs. The strain tolerance has been characterized byDsand segmentation crack length quantitatively. The failure mechanism of APS-TTBCs can be attributed to the propagation of segmentation crack at the top-coat of the TTBCs, formation and propagation of the horizontal crack at the top-coat/TGO (thermally grown oxide) interface. The propagation rate of the main segmentation crack has been calculated and the life prediction model of the TTBCs during thermal cycle has been established. The possible methods which can prolong the service life of the TTBCs have also been proposed.