具有“桩钉结构”增强体的热障涂层抗热震行为与机理研究

The project aims at the fatigue spallation problems of thermal barrier coatings which service in the thermal cycling conditions. Based on the coating structure innovation and the composite technology of preparation, the sprayed thermal barrier coatings are laser modified to create a peg-nail structure. In this project, the holistic design and the guiding fabricating of thermal barrier coatings with peg-nail structured strengthen units are studied. After that, some important characteristics are investigated systematically including the microstructure, the interface and bonding strength, especially the thermal shock resistance, the heat insulation performance and their control methods. Furthermore, the thermal service behaviors and evolution of thermal barrier coatings with peg-nail structured strengthen units are mainly studied. In addition, the thermal shock resisting mechanism is revealed. A new concept of peg-nail structured strengthen unit is put forward in this project, so as to provide a new way for modifying the thermal barrier coatings. Thus, the fatigue spallation problems of thermal barrier coatings are expected to be solved by coupling multiple features such as shapes, structures, organizations and etc., which is benefit for enriching the theory researching system of thermal barrier coating modification. The achievement of this project will establish theoretical foundation for further application of thermal barrier coatings.

本项目针对等离子喷涂热障涂层在热循环服役条件下的疲劳剥落问题，以涂层结构创新和制备技术复合为双切入点，对喷涂态热障涂层进行基于“桩钉结构”的激光改性。本项目针对性地研究具有“桩钉结构”增强体的热障涂层整体设计和理想化构筑方法，系统研究具有“桩钉结构”增强体的热障涂层组织、界面与结合强度，特别是其抗热震性能和隔热性能的指标及调控方法，在此基础上重点研究具有“桩钉结构”增强体的热障涂层在热循环条件下的服役行为和演变，揭示其抗热震机理。本项目提出了“桩钉结构”增强体新概念，为热障涂层改性研究提供了新途径，通过形态、结构、组织等多元特征的相互耦合解决热障涂层在热循环条件下的疲劳剥落问题，有利于丰富热障涂层改性研究理论体系，为热障涂层技术的进一步工程化应用奠定基础。

热障涂层（TBCs）技术是航空发动机发展的关键技术之一，随着航空发动机推重比、进口温度不断提高，对TBCs涂层技术提出了更加苛刻的要求，TBCs涂层技术的核心难题是涂层的热疲劳剥落失效，针对这个问题，本研究提出了“桩钉结构”的激光表面改性新技术，进一步提高热障涂层的抗热疲劳性能。.项目重点研究了“桩钉结构”激光改性热障涂层的组织与特性、界面与结合以及热循环服役行为和演变过程，改善了热障涂层抗热疲劳性能并揭示了作用机理，为提高热障涂层使用寿命，拓展应用空间奠定理论与实践基础。.项目研究结果表明：“桩钉结构”激光改性可以显著提高等离子喷涂热障涂层的抗热震性能，脉宽4 ms、单元体表面积比8%的双陶瓷层“桩钉结构”LYSZ/LCO涂层在抗热震性能较好，是喷涂态YSZ涂层的1.9倍，且“桩钉结构”激光改性比传统的激光重熔和激光上釉方法对于提高热障涂层抗热震性能更为有效；其中脉宽4 ms、单元体表面积比为8%的双陶瓷层“桩钉结构”LYSZ/LCO涂层具有最佳综合性能；通过双陶瓷层设计可以改善“桩钉结构”激光改性热障涂层的隔热性能，特别双陶瓷层“桩钉结构”激光改性LYSZ/LCO涂层的隔热性能相对喷涂态YSZ涂层最高提高了77%；.“桩钉结构”激光改性热障涂层的热震失效的主要原因是热循环过程中产生的热应力作用的结果；与喷涂态组织相比，激光改性“桩钉结构”单元体自身具有优异的抗热疲劳裂纹萌生能力，独特的“桩钉结构”组合可以对热震裂纹的扩展形成有效的阻滞作用，“桩钉结构”激光改性方法在充分发挥其“钉扎效应”和“双相混合强化效应”的基础上产生了优异的抗热震性能。