超音速等离子喷涂制备梯度功能热障涂层的特点

在国内最新研制成功的超音速等离子喷涂系统基础上,开发了国内外独创的“双通道、双温区”超音速等离子喷涂工艺,将高熔点陶瓷粉末和低熔点合金粉末分别送入等离子焰流的不同温度区,保证两种粉末分别达到各自的熔点,再均匀混合后以超音速喷射到基体形成涂层,克服了传统的“金属/陶瓷混合法”制备梯度热障涂层时,低熔点金属相过熔而引起的氧化、脆化问题。制备出的Ce-YSZ/NiCoCrAlY梯度功能热障涂层(FG-TBCs)组织结构均匀致密,陶瓷与金属组份呈连续梯度分布,显示出良好的韧性。在自行开发的多功能旋转式热震试验机上对约1 mm厚的涂层经1 200℃加热、淬水,200周次热震试验后,涂层表面仅出现了细微网状裂纹,裂纹垂直向下扩展最深350μm,止于梯度层中塑性金属区,未发现任何涂层剥落现象。

Characteristics of Functionally Graded Thermal Barrier Coatings Deposited By Supersonic Plasma Sprayed

The functionally graded Ce-YSZ/NiCoCrAlY thermal barrier coatings(FGTBCs) were prepared using a recently developed Supersonic Plasma Spraying(S-PS) system with dual powder feed ports in which the alloy powders were fed into the lower temperature regions of the plasma plume to prevent it over oxidation,and the ceramic powders was fed into high temperature regions for fully melted.The FG-TBCs structure exhibited a finely lamellate microstructure mixed by alloy and ceramic with gradient along the thickness direction by SEM,and thermal shock behavior of the totally 1 mm thick FG-TBCs system were investigated after 200 cycles by a oxygen-acetylene flam to 1 200℃ and then quenching into ambient water using a multi-functional rotational thermal shock tester that developed ourself.It was showed that FG-TBCs exhibit only a finely network state surface cracks and them propagated vertically only about 350 μm deep and stopped to the NiCoCrAlY-rich areas with higher toughness without any spallation.