P3K-5 Passive Materials for High Frequency Ultrasound Components

This study reports the design of materials suitable for backing in piezocomposite devices specifically operating at frequencies above 30MHz. Tungsten loaded epoxy backing samples were made with varying volume fractions with l-5 mum tungsten powder and RX771/HY1300 epoxy. Higher volume fractions were achieved with high shear milling exploiting a new material fabrication technology using PVB polymer, without the need for pressing. Acoustic measurements were carried out at 36MHz to characterise the samples for use in both single element transducers and arrays. The variation in longitudinal and shear wave velocities and acoustic impedance follow the Devaney scattering model with the acoustic impedance ranging from 3-15MRayls. The results show that this material is suitable for use as backing in high frequency piezocomposite devices and acoustic properties can be tailored by adjusting the volume fraction of tungsten.