04 New matching layers to strengthen the metrological characteristics of some ultrasonic transducers

Proper matching layer can increase the energy transmitted efficiency from the transducer’s front and it can reduce energy loss due to reflection, so it can improve the transducer’s sensitivity. Therefore, the right choice of matching layer is very important. Single and double matching layers - made of copper, silver and silver-nickel - were added on normal transducers’ front. The choice of these materials was according to the calculation of their acoustic impedances. The used transducers had frequencies of 2, 4 and 6MHz. The aim was to enhance these transducers, which are the most used in our lab (Ultrasonic measurements lab, NIS, Egypt) for calibration and testing work. Ultrasonic measured different metrological transducers’ characteristics such as near field (N), beam diameter (BD), beam directivity (D), transducer sensitivity (S), transducers waves’ reflections (R) and transmission (T), signal to noise ratio (SNR) and bandwidth (BW). From the analysis of the obtained results, the effect of matching layers was deduced. Finally, using the modified transducers flaw detection was recorded to know the effect of adding matching layer on the detection of different flat bottom holes in steel specimens.