纳米ZrO_2热障涂层烧蚀及失效行为研究

STUDY ON ABLATION AND FAILURE BEHAVIOR OF NANO-ZrO2THERMAL BARRIER COATING

对纳米ZrO2表面涂层试样进行了冷却和无冷却两类等离子风洞烧蚀实验考核,并对实验后的试样表面进行了扫描电镜(SEM)分析,实验发现纳米ZrO2表面涂层存在两种破坏模式,即表面剥落和裂纹.通过对实验过程进行热应力耦合瞬态有限元模拟计算,分析了两类实验中试样的温度场和应力应变场分布,通过分析可知:试样表面纳米ZrO2热障涂层抗烧蚀的温度为1900K以上;无冷却试样的受热破坏模式主要为压剪破坏;背部有冷却试样的破坏包含两种机制,即压剪和屈曲失稳,且屈曲失稳破坏是由于停止加热后基体的快速降温所致.该研究结果可为表面纳米ZrO2热障涂层的设计分析提供依据,所采用实验和分析方法也可用于进一步探讨复杂环境下高温构件表面热障涂层的烧蚀及失效行为.

The ablation experiment for two types of specimens of Nano-ZrO2thermal barrier coating with and without back cooling is carried out in plasma wind tunnel.Specimen surfaces are checked with SEM after testing.It is found that there are two failure modes for Nano-ZrO2surface coating in the experiments,i.e.,surface spalling and cracking.The distribution and evolution of temperature field and thermal stress/strain field of the two specimens during the experiment processes are numerical simulated by the coupled transient finite element method.The results reveal that the anti-erosion temperature of the specimen with Nano-ZrO2thermal barrier coating is up to 1900K.The failure of the Nano-ZrO2thermal barrier coating on the specimen without back cooling is mainly caused by compression and shear.On the other hand,two failure mechanisms exist for the Nano-ZrO2thermal barrier coating on the specimen with back cooling,i.e.,compression-shear and buckling.Buckling failure is due to rapid cooling of the matrix after heating.The results can provide the basis for analysis and design of Nano-ZrO2thermal barrier coating.The experimental and analytical methods can also be used for further discussion on ablation and failure behavior of thermal barrier coating for the high temperature components in complicated thermal environment.