无冷却喷涂工艺对其制备的热障涂层的裂纹系统和寿命的影响

无冷却喷涂形成的热障涂层裂纹体系，可提高陶瓷顶层应变容限.但目前缺乏对裂纹体系的系统研究，特别是横向分叉裂纹.因此，文中研究送粉率和基体预热温度对陶瓷顶层裂纹系统的定量影响，并比较不同裂纹系统的热循环寿命.结果表明，增加送粉率，垂直裂纹密度和横向分叉裂纹长度均呈现先大后小的趋势.预热温度的提高可增加涂层中垂直裂纹数量，但横向分叉裂纹长度呈现先增后降的趋势.热循环试验表明，维持一定垂直裂纹的同时，降低横向分叉裂纹可提高涂层热循环寿命.

Effect of thermal spraying parameters on cracking and thermal cycling life of thermal barrier coatings

Segmentation cracks can be formed in the top ceramic coatings of thermal barrier coating system by the thermal spraying process without any cooling. The crack system can strengthen the strain tolerance of ceramic coatings. Up to now, there are almost no systemic studies on the cracking, especially on the branch cracks. The quantitative effects of feeding rate and substrate preheating temperature were studied on the cracking in this paper. And the thermal cycling lifetimes of coatings with different cracking systems were compared. It was found that with the increase of feeding rate, the density of vertical cracks and length of branch cracks increase firstly and then decrease. The density of vertical cracks shows an increment tendency with the increase of substrate preheating temperature. However, the length of branch cracks increases firstly, and then shows a decreasing trend. It shows that the lifetime of the top ceramic coatings can be improved effectively through restraining the total length and number of branch cracks in coating and maintaining the density of segmentation cracks at a certain level.