热障涂层界面脱粘缺陷的脉冲红外热成像检测

针对热障涂层界面脱粘缺陷的无损检测问题，首先制备了一种导热过程更加接近真实缺陷，且尺寸可控的人工模拟脱粘缺陷试样；在此基础上，采用脉冲红外热成像检测技术对人工脱粘缺陷进行检测，分析了涂层界面脱粘区和非脱粘区的表面温度瞬态响应过程；以图像标准差（SD）和归一化对比度（NC）作为评价标准，定量对比了脉冲相位法、主成分分析和表面热信号重构3种典型的热图重构方法在脱粘缺陷识别中的作用。结果表明，对400 μm厚的YSZ热障涂层，原始热图中可识别最小直径为4 mm的脱粘缺陷，而3种重构热图中均可识别最小直径为2 mm的界面脱粘缺陷，3种重构算法均显著提高了界面脱粘缺陷的识别能力，其中以表面热信号重构算法对图像的噪声抑制能力最强。

Inspection of interface debonding in thermal barrier coatings using pulsed thermography

This paper aims at soloving the nondestructive testing problem of interface debonding defect of thermal barrier coatings. Firstly, a preparing method for specimen with artificial debonding defects is proposed, providing more realistic thermal conduction process and controllable defect size. On this basis, pulsed thermography is employed to detect the coating specimen with artificial debonding defect, and the transient response process of the surface temperatures in debonding region and sound region of coating interface is analyzed. Standard Deviation (SD) and Normalized Contrast (NC) are used as evaluation criteria to quantitatively compare the effects of three typical thermal image reconstruction methods, which are PPT, PCA, and TSR, in the identification of debonding defects. The results indicate that, for YSZ thermal barrier coatings with a thickness of 400 μm, the debonding defects with a minimum diameter of 4 mm can be identified in raw thermal image sequency, while the debonding defects with a minimum diameter of 2 mm can be identified in all three reconstructed image sequences. The identificating ability of debonding defects have significantly improved by three reconstruction algorithms, among which the TSR reconstruction algorithm provided the best noise suppression ability for thermal image sequence.