YSZ 颗粒在电弧等离子射流边界层的自组装团聚行为及其对热障涂层显微结构的影响

This project wants to study the relationship between the microstructure evolution and thermal cycling reliability of plasma sprayed YSZ coatings, which widely used on the surface of the blade of aircraft engines. The columnar or quasi-columnar structures of YSZ coatings are all obtained by using SPS, SPPS or PS-PVD methods at different conditions, which is a research front for manufacturing of Thermal Barrier Coatings. Moreover, authors find that the quasi-columnar YSZ coatings can also be deposited by using the novel long laminar plasma spraying methods at atmospheric environment. However, it remains unclear how the columnar or quasi-columnar YSZ coatings formed during different plasma spraying processes whatever in atmospheric environment or low – pressure condition. The formation and mechanism of microstructures of YSZ coatings still had not a consensus for researchers. Therefore, authors want to focus on the heat and mass transfer processing at the boundary layer of plasma spraying jet when the jet impinging on the substrate, especially for the self - assembly agglomeration mechanism at this area by using the novel atmospheric laminar plasma spraying method. The reproduction and controlling methods of columnar or quasi- columnar YSZ coatings in plasma spraying processing are studied. The deeply understanding and fundamental mechanism should be provided in this study. These should all service for the improvement of performances of YSZ coatingse columnar structure and provide basic theoretical support for the development of new plasma spray technology on YSZ coating and deepen the understanding of the new generation of high temperature thermal barrier coating preparation technology from the mechanism of the fundamental issues, providing solutions to improve the service performance of YSZ coating.

本项目着力解决航空发动机多级叶片上的高温功能涂层在制备和服役条件下的显微结构演化与使役稳定性之间的关系。针对目前热障涂层的研究前沿，悬浮液等离子喷涂技术和超低压等离子物理气相沉积技术均可以制备柱状或准柱状YSZ涂层。而申请人最新的研究成果表明，采用新型大气长层流等离子喷涂YSZ涂层技术中也可以获得纳米团簇准柱状结构。目前对于柱状结构YSZ涂层的显微结构演变和产生共性尚无统一的解释模型。本项目以新型大气长层流等离子喷涂为研究对象，通过研究高速高温纳米YSZ流体在通过电弧等离子射流边界层和其撞击母材时的强化传热和传质过程，特别关注纳米YSZ颗粒在该过程中的自组装团聚行为，掌握柱状YSZ涂层结构在电弧等离子喷涂技术中的重复性产生条件和控制方法，为发展新型电弧等离子喷涂YSZ涂层提供基础理论支撑。从关键基础问题的机理上深化对新一代高温热障涂层制备技术的认识，为提升YSZ涂层的服役性能提供解决方案。

通过研究一种新型大气等离子喷涂方法，该方法采用特殊内通道结构的直流非转移电弧等离子发生器，可以直 接在大气条件下获得长度 100~1000 mm 之间变化的等离子射流。在大气条件下，等离子射流的流动特性具有“长、 直、准”的层流或类层流状态，工作时噪音小于 80 dB。在工作参数范围内，等离子射流的长度在固定总气流量条件下 可以随输出功率的增加而增长；射流的长度在固定输出功率的条件下随总气流量的增加而减小。当使用在大气等离 子喷涂技术中时，会为飞行粉末颗粒带来超长的加热和加速过程。本项目研究了大气层流等离子喷涂技术的研究历史和研究现状，以及研究团队利用该新型技术制备的 6 种涂层的显微结构、颗粒的飞行和加热特点，并对比了目前 其他大气等离子喷涂技术的结果。结果表明，文中介绍的方法在最低的输出功率和气流量条件下，为金属和陶瓷颗 粒提供了超长的飞行和加热条件，表现为较低的颗粒飞行速度和超高的颗粒表面温度。可以在不同的射流长度或喷 涂距离下，获得不同的颗粒熔化状态或涂层结构，并发现可以直接在大气条件下获得大规模气液共沉积的涂层。