干冰在线喷射对稀土基热障涂层的原位优化机理研究

Thermal barrier coatings (TBCs) applied on aero-engine hot-section components could significantly increase the resistance to corrosion and oxidation as well as service lifetime at high temperature, and thus improve the engine efficiency. Their lifetime depends on the preparation process and the coating structure. Plasma-sprayed TBCs present a layered-structure and thus have low thermal conductivity, but low thermal-cycling lifetime; while TBCs prepared by EB-PVD technique exhibit a columnar structure, high strain tolerance and thus high thermal-cycling lifetime, but prone to CMAS (CaO-MgO-Al2O3-SiO2) corrosion and high thermal conductivity. In the present project, new rare-earth materials will be used to prepare TBCs by plasma spraying. Moreover, dry-ice blasting is innovatively proposed to be combined with thermal spraying in order to improve the TBCs’ properties. Based on pore-structure control theory, vertical micro-cracks could be implanted in La2Zr2O7, La2Ce2O7 and LaMgAl11O19 ceramic coatings by controlling the quenching stress of the molten droplets. In addition, the interface structure in TBCs systems would be optimized to improve the stress distribution and bonding strength. Thermal cycling and CMAS corrosion behavior of TBCs with implanted vertical-microcracks will be investigated. The failure mechanism of TBCs would be explored. The relationship between the vertical-crack structure, interface morphology, residual stress distribution and TBCs’ lifetime could be established. This project will lay the theoretical foundation for the optimization design of new TBCs with excellent performance at high temperature.

热障涂层（TBCs）应用在航空发动机热端部件上可以显著提高其抗高温氧化腐蚀能力和服役温度，提高发动机的效率。TBCs的服役寿命取决于涂层的制备工艺和组织结构。等离子喷涂制备的TBCs具有层状结构，热导率低，但热循环寿命短；电子束物理气相沉积制备的TBCs具有柱状晶结构，有很高的应变容限，热循环寿命长，但易发生玻璃态沉积物（CMAS）腐蚀且热导率较高。本项目选取新型稀土TBCs材料，基于孔隙结构控制理论，创新性地提出在热喷涂过程中原位喷射干冰微粒, 通过控制熔滴铺展的淬火应力在稀土陶瓷层中植入微观纵向裂纹，通过优化TBCs体系界面结构改善应力分布和结合强度，建立预制微观取向裂纹结构、界面形貌特征和残余应力分布状态与TBCs寿命之间的内在联系。防止CMAS腐蚀的同时，解决高应变缓和与高隔热性能的矛盾，设计苛刻服役环境下高隔热长寿命TBCs，为新一代长寿命耐高温TBCs的发展提供理论支持。

热障涂层（TBCs）应用在航空发动机热端部件上可以显著提高其抗高温氧化腐蚀能力和服役温度，提高发动机的效率。本项目提出了一种在稀土TBCs陶瓷层中植入微观纵向裂纹的新结构和热喷涂过程中原位喷射干冰微粒的耦合工艺方法。按照项目计划书的安排，项目执行和进展顺利，圆满完成了项目研究计划和任务。首先，通过等离子喷涂与干冰微粒喷射耦合方式及流量等对不同稀土陶瓷La2Zr2O7（LZ）、La2Ce2O7(LC)、LaMgAl11O19（LMA）预制微观纵向裂纹的影响规律，建立了干冰微粒喷射对稀土陶瓷隔热层植入微观纵向裂纹的调控机制及粉末敏感性理论，并基于调控理论进一步改善优化了TBCs体系界面结合状态，深入研究评估了预制微观纵向裂纹结构的稀土基TBCs的热震寿命和CMAS腐蚀性能，建立了TBCs微结构与热循环寿命以及CMAS腐蚀行为之间的内在关系理论，最终实现了在保证TBCs隔热效果和抗CMAS腐蚀前提下提高其应变容限和热循环寿命的目标。