YZrHf热障涂层的制备及热震性能分析

目的 研究喷涂态YZrHf热障涂层的微观组织及其抵抗高温热冲击的性能，探讨高温条件下热生长氧化物(TGO)对陶瓷层的影响。方法 采用大气等离子喷涂(APS)技术制备厚度约为300μm的YZrHf热障涂层，并将涂层在950℃下保温15 min后进行水冷循环热震实验，直至涂层剥落失效，使用SEM、EDS、X射线衍射仪对制备态及热震实验后的热障涂层微观组织进行分析。结果 涂层表面粗糙不平且分布有十几到几十微米长度的网状裂纹，这些相互贯通的裂纹为氧气的进入提供了通道。经过101次循环热震实验后，涂层部分区域剥落失效，SEM结果显示，在陶瓷层/黏结层界面处、黏结层内部均出现了热生长氧化物，且在陶瓷层中分布有横向、纵向的贯通性裂纹，而在TGO生长区域，也出现了一些小裂纹，但涂层并未剥落。经测定分析可知，TGO的主要成分为Al₂O₃、Cr₂O₃、NiO以及尖晶石氧化物组成的混合物(CSN)。结论 热震实验后TGO层中Al元素贫化，Ni、Cr等元素向界面处迁移参与反应，同时尖晶石氧化物以α-Al₂

Preparation and Thermal Shock Performance Analysis of YZrHf Thermal Barrier Coatings

The work aims to study the microstructure of the YZrHf thermal barrier coating and its resistance to high temperature thermal shock, and to investigate the effect of the growth of thermal growth oxide (TGO) on the ceramic layer at high temperature.A YZrHf thermal barrier coating with a thickness of about 300 μm was prepared by atmospheric plasma spraying (APS) technology, and the coating was keep at 950 ℃ for 15 min and then subject to a water cooling cycle thermal shock test until the coating failed. SEM, EDS and X-ray diffraction were used to analyze the preparation state and the microstructure of the thermal barrier coating after thermal shock. It was found that the surface of the coating was rough and uneven, and there were mesh cracks with lengths of ten to dozens of microns. These interconnected cracks provided a channel for oxygen to enter. After 101 high temperature thermal shock experiments, some areas of the coating were spalling and failing. Through SEM observation, thermal growth oxides appeared at the interface of ceramic layer/bonding layer and inside the bonding layer, and transverse and longitudinal penetrating cracks were distributed in the ceramic layer. In the TGO growing area, some small cracks appeared, but the coating did not peel off. The determination analysis showed that the main components of were Al2O3, Cr2O3, NiO and other mixtures composed of spinel oxide (CSN). After the thermal shock experiment, Al elements in the TGO layer is depleted, Ni, Cr and other elements migrate to the interface to participate in the reaction, and spinel oxides are formed on the basis of α-Al2O3. The existence of these oxides will produce compressive stress on the ceramic layer and accelerate the cracking failure of the coating. The doped HfO2 in the coating can prevent the external diffusion of Al and reduce the growth rate of the oxide layer.