Research On The Technology Of Thermal Barrier Coating Structure Defects Detection Using Pulsed Infrared Thermal Wave Non-destructive Testing Method

Thermal barrier coating which is one of the best performance of high-temperature protective coating, with heat insulation, corrosion resistance, abrasion resistance, erosion resistance and heat insulation. In recent years, it has a broad application prospect and widely used in power machinery, aerospace and other high temperature and high heat flux environment. In the thermal barrier coating structure of service process, prone to coating cracking and debonding and peeling defects, influence the hot end parts running safety and reliability, even catastrophic consequences. Therefore, it is very necessary to detect and evaluate in real time by using non destructive testing technology.Infrared thermal wave nondestructive detection technology with high detection efficiency, simple and safe operation, non-contact, etc., with removal of bonding defects in thermal barrier coating component detection provides a new method. Therefore, this paper on Microstructure of thermal barrier coating off stick defects pulse infrared thermal wave nondestructive detection theory analysis and finite element simulation and test system to build and test, image sequence processing algorithm, edge defect detection and recognition technology to carry out a systematic in-depth study.Based on the theory of heat transfer and material science, Laplace transform is applied for pulse excitation containing defects in semi infinite flat plate component heat conduction differential equation of one-dimensional analytical solution, the defect area and defect area of surface temperature changes in the expression; To the structure of the thermal barrier coating off stick defects as the research object, through the finite element simulation analysis of the removal of bonding defects in diameter size, output power of light source and sampling frequency characteristic of surface temperature signal effect of and for the subsequent detection system to build and test research provides a theoretical basis.Built the pulse infrared thermal wave nondestructive detection system for experiment and realized on YSZ(6%~8%Y2O3 stable Zr O2) thermal barrier coating structure off the reliable detection of defects in bonding. Studied preparation of thermal barrier coating structure simulation of debonding specimens of the new method, discusses the heating and cooling process, the output power of light source and sampling frequency on the detection effect of, and the main reason for the difference between simulation and experimental results are analyzed.Study the pulse infrared image sequence processing algorithm(logarithm polynomial quasi legal, SVD singular value decomposition method), and the reconstruction of the imagesequence is performed, realizes the component surface temperature signal feature information extraction, compared with the original thermal image, image processing improves the contrast and signal-to-noise ratio; The classical edge detection operator, Canny and Log of the infrared image of edge detection, and on the analysis of the testing results based on the Retinex-Watershed-Canny operator of the hybrid algorithm for image edge detection based on, the realization of the thermal barrier coating structure identification of stick defect edge removal, to lay a certain foundation for the defect quantitative detection.