Erosion morphology test method of thermal barrier coating based on terahertz technology

Abstract

The invention provides an erosion morphology test method of a thermal barrier coating based on a terahertz technology. The method comprises the following steps of vertically emitting terahertz pulsesby using a reflective terahertz time-domain spectroscopy system to the thermal barrier coating; obtaining a time domain spectrogram; extracting the moment value of the front three times of reflectionpeaks in the spectrogram; obtaining the time delay of the two adjacent peaks; performing Fourier transform on the front three times of reflection peaks to obtain a frequency domain spectrogram; calculating the refractive index and the thickness of the ceramic layer of the thermal barrier coating; performing erosion on the thermal barrier coating; performing scanning; using the time-domain spectroscopy system for measurement so as to obtain a plurality of time-domain spectrograms; extracting the moment value of the first time reflection peak in the spectrogram; calculating the difference from the moment value of the first time reflection peak; calculating the thinning thickness value of the thermal barrier coating according to the difference value; obtaining the erosion morphology of the thermal barrier coating. The test method has the advantages that the step of measuring the refractive index of the thermal barrier coating is omitted; the thinning thickness of the thermal barrier coating after the erosion is calculated, so that the calculation by using the refractive index of the thermal barrier coating is not needed; therefore the error is reduced.

Description

technical field [0001] The present invention relates to an erosion test method, in particular to a test method for the erosion appearance of a thermal barrier coating based on terahertz technology. Background technique [0002] Aeroengines are known as the "crown jewel" in the high-end manufacturing industry. With the rapid development of aeroengine technology, in order to improve the performance and efficiency of the engine, the thrust-to-weight ratio of the engine has been continuously improved. Take the development history of the engine as an example: the thrust-to-weight ratio of the engine has grown from less than 2 to more than 10. At present, the inlet temperature of the gas turbine has exceeded 1973K, and the temperature of the service parts is getting higher and higher. In order to protect the parts from being oxidized and corroded, the above In the 1950s, NASA first proposed the concept of thermal barrier coating, that is, depositing a layer of thermal barrier coat...

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Problems solved by technology

However, it is necessary to obtain the optical refractive index parameters of the tested material by other means in advance, that is, the refractive index of the tested material needs to be re-prepared and tested, and the re-prepared sample cannot guarantee the same refractive index as the tested sample. They are exactly the same, but there are errors, and if additional new experiments are required to obtain the refractive index of the measured material in actual engineering use, the convenience will be greatly reduced; in addition, the content of these two patent documents does not involve the impact of thermal barrier coatings. In the application of erosion measurement, after the thermal barrier coating is eroded, new cracks and pores will be added inside the remaining coating, which will lead to changes in the refractive index of the ceramic layer. If the erosion is performed based on the original thickness calculation model and refractive index The calculation of the thickness after erosion will inevitably introduce a large error. If you continue to use this method to measure the thickness of the coating after erosion, the actual measurement error will continue to increase with the erosion

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