基于小波分析的热障涂层厚度超声检测

Ultrasonic Testing for Thinkness of Thermal Barrier Coatings Based on Wavelet Analysis

基于超声信号在涂层的上、下表面产生的奇异性,通过对超声信号进行连续小波变换分析,利用模极大值法和Lipschitz指数法进行判断,找出了超声信号中的奇异点。依据热障涂层界面反射信号的时间差,利用已知涂层声速可以算出涂层厚度。通过与扫描电镜所测涂层厚度对比分析,验证了该方法的可行性。

Due to the singularity of the ultrasonic signals from the top and bottom surfaces of the coating, the ultrasonic signals can be analyzed through continuous wavelet transform. And the methods of the modulus maxima and Lipschitz exponential were exploited to determine the singularity of the ultrasonic signals. Therefore, the time difference of the reflected signals on the coating interface can be obtained and thickness of the coating can be calculated by using a known speed of sound of the coating. Finally, the results are compared with the coating thickness measured by the SEM to verify the feasibility of this method.