复合陶瓷涂层中连续过渡区的等离子喷涂构筑及其界面阻裂机制研究

利用热喷涂技术制备表面陶瓷涂层是机械关键部件的迫切需求，而陶瓷涂层中传统双层（陶瓷层加粘结层）结构导致其断裂脱落已经成为其应用瓶颈，形成高断裂韧性的界面结构是提高涂层寿命的关键。利用等离子喷涂构筑高断裂韧性的陶瓷涂层连续过渡区，揭示其界面阻裂机理，是设计并制备长寿命陶瓷涂层急需解决的科学问题。本项目利用微裂纹和残余压应力增韧效应，构筑合金和陶瓷的颗粒连续过渡区，形成热膨胀系数连续变化，从而提高涂层的粘结性能，同时揭示其界面阻碍微裂纹生长的机制。具体利用模拟计算和实验，确定等离子喷涂参数与飞行颗粒的相互影响关系，获得涂层构筑参数对过渡区特征的影响机制和规律；然后利用显微压痕法揭示连续过渡区特征对其阻裂能力的影响和映射关系；最后进一步的优化和制备不同厚度和特征的过渡区，明确其对整体陶瓷涂层断裂韧性的影响。本项目可为陶瓷涂层提供一种新的理论设计及制备方法，为制备高温长寿命陶瓷涂层奠定基础。

Postponing the failure of mechanical surface ceramic coatings is an urgent requirement for advanced high performance key components. The traditional design about double-layer (ceramic with bond-layer) within the ceramic coatings, which could result the failure at the ceramic/bond-layer interface, has become a bottleneck in its application. The formation of a new interface structure with high fracture toughness is the key to improving the life of the coating. Constructing continuous transition zone of ceramic coatings by plasma spraying, and revealing the mechanism of interfacial crack resistance is a scientific problem to be solved urgently for the design and preparation of new long-life ceramic coatings. In this project the microcrack and residual compressive stress toughening effect was adopted to construct a continuous transition zone using by alloy particles and ceramic particles, forming a continuous transition of thermal expansion coefficient, thereby improving the bond performance of the coating and revealing its mechanism of hindering the growth of microcracks. Firstly, the interaction between plasma spraying parameters and flying particles is determined by simulation and experiment. The mechanism and influence of coating construction parameters on the characteristics are obtained within continuous transition zone. Then, the influence of the characteristics of continuous transition zone on its crack resistance and mapping relationship are revealed by micro-indentation method. Finally, the thickness and characteristics of the transition zone were further optimized to clarify its effect on the fracture toughness of the ceramic coating system. This project can provide a new theoretical design and preparation method for ceramic coatings, and make a contribution for the application of long life ceramic coatings at high temperature.