激光-电火花沉积复合制备热障涂层界面耦合与TGO演化机制研究

Thermal barrier coatings (TBCs) have been widely utilized in aviation, aerospace and energy industries. However, uncontrollable micro-structure and poor resistance to high temperature oxidation and thermal shock are seriously restricting the development of TBCs. By studying the interaction of laser, Electrical Discharge Deposition (EDD) and TBCs materials, a new model for laser melting and EDD melting heat and mass transferring will be established. The sedimentary thickness, organization structure and the regularity of element diffusion which are resulted from different material mix proportion, will be studied. The YSZ powder coated by MCrAlY and the YSZ conductive pole mixed with MCrAlY will be designed and developed. Then the experiments that laser-EDD compositely fabricates gradient TBCs will be carried out. The relationship between the formation, growth and defects of the thermal growth oxide layer (TGO) and TBCs failures will be discussed. It is also needed to analyze how the interface, morphology and thickness of coating and TGO influence thermal cycling residual stress, cracks and delamination. SHPB experiments will be implemented, the coating material stress-strain curve will be plotted, the dynamic constitutive relation will be built and the coating stress and strain and deformation mechanism under the condition of heat will be discussed. It is expected to make a breakthrough in the theoretical and experimental aspects of materials thermodynamics constitutive properties and TBCs new process. Coated YSZ material and MCrAlY-YSZ electrode will be developed and the coating material constitutive test and analysis method based on the SHPB experiment will be designed. And the new phenomena and mechanisms of coating interface coupling, stress-strain and coating failure will be explored.

热障涂层广泛应用于航空、航天、能源等领域，但涂层微观结构不可控，抗高温氧化和热震性差，成为制约其发展瓶颈。通过研究激光、电火花与热障涂层材料的相互作用，建立激光熔池和电火花熔化传热传质模型；研究不同材料混合比例沉积厚度、组织及元素扩散规律；研制MCrAlY包覆YSZ粉末与MCrAlY混YSZ导电极，开展激光-电火花沉积复合制备梯度热障涂层实验；研究热生长氧化层（TGO）的形成、生长与缺陷产生及失效间关系，分析涂层与TGO界面、形貌、厚度等对残余应力及裂纹、脱层影响。进行SHPB实验，建立涂层材料应力应变曲线，构建其动态本构关系；研究涂层受热状态下应力应变及变形机制。有望在材料热力耦合本构关系及热障涂层新工艺方面取得理论和实验突破，研制出包覆型YSZ材料与MCrAlY-YSZ电极，设计出基于SHPB实验的涂层材料本构测试与分析方法，探索涂层界面耦合、应力应变与涂层破坏的新现象和新机理。

热障涂层是采用耐高温和低导热的陶瓷材料以涂层的方式与金属相复合，降低高温环境下金属表面温度的一种热防护技术。热障涂层广泛应用于航空、航天、能源等领域，可显著降低涡轮叶片表面温度，大幅度延长叶片工作寿命，提高发动机或燃气轮机的推力和效率。本项目主要针对激光-电火花沉积复合制备热障涂层的界面耦合与TGO演化机制进行研究。构建了激光熔覆MCrAlY/YSZ复合涂层的工艺数据库，在MCrAlY包覆YSZ粉末、MCrAlY混YSZ导电极及其涂层设计和制备上，取得了一定的理论、方法和技术创新。利用有限元、实验与CCD视觉检测相结合的方法，研究了CoNiCrAlY激光熔池的传热传质行为和有限元模型，得到了不同工艺参数下，熔池的温度场分布、几何尺寸、寿命和残余应力数值仿真模型，实现了CoNiCrAlY熔池行为的有限元预测，表面温度场、几何尺寸和流动速度的视觉检测。采用双送粉方式，实现了CoCrAlSiY和YSZ不同混合比例的单道、多层和梯度CoCrAlSiY/YSZ复合涂层的制备，涂层与基体、各梯度层间界面结合良好，没有明显的界面和缺陷，沿梯度方向，各元素比例和涂层硬度连续变化。研制了NiCoCrAlY包覆YSZ粉末，并利用激光熔覆NiCoCrAlY包覆YSZ粉制备了NiCoCrAlY/YSZ梯度涂层；高温氧化过程中，Al元素由涂层内部向表面聚集，与氧元素在涂层表面形成了一层均匀的TGO层，阻止了氧元素向涂层内部的进一步扩散和涂层内部氧化失效。采用SPS方法制备了不同比例NiCoCrAlY-YSZ电极，进行了电火花沉积实验，获得了小稀释率和均匀致密的NiCoCrAlY/YSZ复合涂层。开展了SHPB实验，建立了高应变率下激光熔覆NiCoCrAlY应力应变曲线，研究了激光熔覆NiCoCrAlY材料高应变率下的变形机制，并建立了激光熔覆NiCoCrAlY本构模型。研究了叶片基体或涂层修复的自适应定位问题，提出了一种基于散斑视觉测量的叶片修复自适应定位方法，搭建了自适应定位系统的软硬件平台，实现了叶片类复杂零部件的自适应定位。