钪钇共稳二氧化锆热障涂层结构设计与热冲击失效行为研究

Structural Design and Thermal Shock Failure Behavior of Scandium and Yttrium Co-stabilized Zirconia Thermal Barrier Coatings

热障涂层的微观结构是影响其使役性能的关键因素。研究了亚微米及纳米“双模式”结构钪钇共稳二氧化锆(Sc YSZ)热障涂层的微观结构与高温热冲击行为。结果表明,亚微米结构Sc YSZ涂层在1300℃的火焰热冲击寿命为286次,而纳米未熔颗粒/层状组织“双模式”结构可以显著提高涂层的热冲击寿命,其热冲击寿命达到376次。亚微米结构涂层致密性较高,热冲击过程中容易发生高温烧结导致贯穿涂层厚度方向的纵向裂纹产生,而纳米“双模式”结构涂层中的纵向裂纹遇到疏松的纳米未熔颗粒因应力释放而终止,其失效模式主要表现为未熔颗粒的点状剥落。

Microstructure of the thermal barrier coatings is a key factor affecting its service performance. The microstructure and thermal shock behavior of scandium yttrium co-stabilized zirconia(ScYSZ) thermal barrier coatings with sub-micron and nano-sized bimodal structures were investigated. The results show that the thermal shock life of the ScYSZ coating with sub-micron structure is 286 times at 1300 ℃. While the bimodal-structured coating with nano-sized unmelted particles/layered structure can significantly improve the thermal shock life of the coating, which reaches 376 times. The microstructure of sub-micron coating is relatively dense, and the vertical cracks through the coating thickness are easily to generate during the high-temperature thermal shock test. However, the propagation of vertical cracks in the nano-coating are terminated by the stress release encountering the loose nano-unmelted particles. The main failure mode of the nano-coating is the spot spallation.