面向热障涂层内部界面缺陷的快速检测装置

Rapid detection instrument for interface defects of thermal barrier coating

热障涂层(TBC)对燃气轮机涡轮叶片的保护起着至关重要的作用,但是其内部陶瓷层与黏结层界面易产生热氧化层和局部应力集中而诱发界面分层缺陷,严重危害TBC的服役安全,因此,实现TBC内部尤其是界面缺陷的无损快速检测对于叶片服役寿命评估具有重要工程意义。然而,现有的检测装置均不能满足无损、快速、精准以及便携的测量需求,为此本文开展了基于荧光成像的热障涂层内部界面缺陷的装置研究。本文基于荧光反射增强效应,设计搭建了采用同轴带通光路的检测装置。同时,探索了在荧光子层下方预制内部界面缺陷的实验方法,制备了用于验证方法与标定测量的预制界面缺陷TBC试样。最后,将所研制的检测装置应用于识别所制备样品的内部缺陷,通过对不同横向尺寸、形状与厚度预制缺陷的准确识别检测,验证了装置的有效性与适用性。

Thermal barrier coating(TBC)plays an important role in the protection of turbine blade.The delamination defect at the interface between the top coating and the bonding coating could seriously endanger the service safety of TBC,caused by the thermally grown oxide and the local stress concentration.Thus,for the evaluation of blade service life,it is of great engineering significance to realize the nondestructive and rapid detection of TBC interface defect.While,the existing detection technology cannot meet the requirements of nondestructive,rapid,accurate and portable measurement.This work carried out an investigation on the detection method and equipment based on fluorescence imaging.According to the principle of reflectance-enhanced fluorescence,a self-built instrument was designed and established based on bandpass coaxial optical path.Meanwhile,this work explored the method and procedure of prefabricated interface defect under the fluorescent sublayer,subsequently prepared TBC samples with kinds of prefabricated defects.Finally,the developed instrument was applied to identify the interface defects of the prepared samples.The accurate identification of prefabricated defects with different transverse sizes,shapes and thicknesses verified the effectiveness and applicability of the proposed method and device in this work.