热障涂层闪光灯激励红外热像检测

Infrared Flash Thermographic Nondestructive Testing of Defects in Thermal Barrier Coating

为了跟踪和记录热障涂层缺陷产生、发展直至脱落的过程,对热障涂层试片组进行热循环实验,在实验前和不同实验阶段分别对各个试片进行闪光灯激励红外热像检测;对发现的可疑区进行了解剖分析,识别出微裂纹;利用含有自然缺陷和人工缺陷的试片对红外热像检测的检测能力进行了评价。结果表明:闪光灯激励红外热像检测技术能够检测出直径小于0.5mm的脱粘缺陷,还能够识别出微裂纹态,这种状态用肉眼从涂层表面无法识别;闪光灯激励红外热像检测技术不仅可用于热障涂层的缺陷检测,还有希望用于热障涂层的寿命评估。

To keep track of the process of generation and development of cracks and debonding defects in thermal barrier coating, a set of test pieces with thermal barrier coating deposited on both sides were made and went through hundreds of working cycles. Infrared thermographic nondestructive testing（NDT） experiments were made on those pieces before working cycles and after different number of working cycles. Abnormal areas found in the pieces were analysed by SEM observation on cross sections, and small cracks were identi- fied. The experiments on test pieces with natural defects and artificial defects were made to evaluate the ability of infrared thermographic NDT. Based on those experimental results, it is concluded that small cracks which cannot be observed the from the coating surface can be identified in infrared flash thermographic NDT, and debonding areas which are less than 0.5 mm in diameter can also be detected by using the NDT technology. Infrared flash thermography is suitable for NDT of the defects in thermal barrier coating.