Metal-Polymer Composite as an Acoustic Attenuating Material for Ultrasonic Transducers

Abstract

This work reports the acoustic evaluation of a tungsten-epoxy composite which is functioned as a backing material of an ultrasonic transducer. The composite is prepared by mixing tungsten powder in epoxy at a weight ratio of 4:1 using a shaker milling and curing the mixture under a vacuum condition. The sound velocity and acoustic attenuation in the prepared composite is measured by propagating a 200-kHz ultrasonic wave with a through transmission mode. The prepared composite is subsequently assembled with a 1-MHz piezoelectric disk (PZT-8) and an epoxy layer as the active element and the matching layer, respectively, into a fabricated ultrasonic transducer. A square-wave burst pulse is used as an excitation signal for the evaluation of the fabricated transducer. The generated ultrasonic wave shows a higher damping in the presence the backing layer. In addition, the measured sound velocity and acoustic attenuation of prepared composite showed that the ratio of 4:1 is sufficient composition in order to apply as a backing material. In conclusion, control the transducer characteristics is determined by the acoustic properties of tungsten-epoxy composite.