DEVELOPMENT OF A BROAD-BAND ULTRASONIC TRANSDUCER FOR HIGH-TEMPERATURE APPLICATIONS

The construction and test of a broad-band transducer designed to work in the temperature range from 20 degrees C to 250 degrees C are reported. The variation of acoustic and piezoelectric properties of different active and passive materials were measured in order to select the appropriate materials and to simulate the transducer behaviour at different temperatures by using a numerical model based on the KLM equivalent circuit. The comparison between theoretical and experimental results shows that the characteristics of the transducer such as centre frequency and bandwidth remain stable in the operating temperature range, and that the variations of echo amplitude with temperature are mainly due to the modification of the couplant acoustic properties.