Thermal barrier coatings (TBCs) have been widely used in hot end components of engines, such as blades and combustors, due to their high temperature corrosion resistance, heat insulation and oxidation resistance. The thermal conductivity, constant pressure heat capacity and coating thickness are important indexes in the design process of TBCs. A reasonable coating thickness is an important criterion for its quality evaluation. In this paper, pulsed thermal imaging multilayer analysis method is used to measure the coating thickness of thermal barrier coating samples. Firstly, a two-layer model is constructed by finite element simulation to obtain the measurement results under ideal conditions, and the method is evaluated. Then, the accuracy of the method is further verified by experiments with five TBC samples with different coating thickness.
In order to measure the thickness of the rusted bronze layer quickly and accurately, an active infrared thermal imaging technique is developed. Pulse flash lamp was used to excite the surface of the specimen, and infrared thermal imager was used to record the temperature decay of the specimen surface before and after flash. This paper presents a pulse thermal imaging multi-layer analysis method (PTI-MLA) which consists of a pulsed thermal imaging (PTI) system to acquire experimental data and a multilayer analysis (MLA) data-processing algorithm to derive parameters of the corroded bronze. This paper studies a bronze pot fragment from the China’s Spring and Autumn period excavated in Sujialong site, Hubei province. The corrosion thickness map of the fragment is calculated and analyzed by PTI-MLA method. Comparing the measured values with the CT scanning results, the error is less than 10%. The final result indicates that the PTI-MLA method can be used to measure the thickness of rust layer on the surface of bronze ware and obtain high-precision thickness images.
Pulse phase thermography (PPT), principal component thermography (PCT) method and Thermal signal reconstruction (TSR) analysis including Logarithmic First-Derivative (LFD) and Logarithmic Second-Derivative (LSD) method have been widely used to improve detection sensitivity and quantitative measurement accuracy in infrared thermal imaging. In this paper, the difference of pulsed thermography results of aluminum specimens with flat bottom holes (FBHs) under PPT method, PCT method and LFD and LSD method was compared. With the result of the above methods, the multi-image average method is proposed to further improve the signal-to-noise ratio at the defect of images. Finally, the difference between the original result and the improved result are compared.
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