Investigation on Coating Uniformity of High-Temperature Alloy with SiC Thermal Barrier Coating Using Pulsed Infrared Thermographic Technique

The SiC thermal barrier coating thickness uniformity of a high-temperature alloy was investigated using a pulsed infrared thermographic image. A thermal quadrupole method is used to solve a one-dimensional thermal conduction model. The temperature of the high-temperature alloy with SiC coating is directly affected by the pulse intensity of optical excitation; furthermore, the relation between the SiC thermal barrier coating thickness and temperature difference is obtained. Pulsed phase thermography and principal component analysis are applied to extract the characteristic information from thermal image sequences, and the signal-to-noise ratio of the thermal wave signal is clearly improved. The thermal contrast of the SiC thermal barrier coating thickness is related to the optical pulse intensity and infrared camera frame rate. Furthermore, a relatively simple quantitative method is developed to estimate the SiC thermal barrier coating thickness uniformity of the high-temperature alloy, and the coating thickness measurement using pulsed thermographic imaging is in very good agreement with the actual coating thickness value.