Fine scale 2-2 connectivity PZT/epoxy piezoelectric fiber composite for high frequency ultrasonic application

Abstract

High frequency piezoelectric fiber composites have extensive application in fields of biomedical imaging, ultrasonic inspection, underwater acoustic imaging and so forth. In this paper, fine scale 2-2 connectivity PZT/epoxy piezoelectric fiber composites were tailored by using the dicing-filling-pressing method with poled ferroelectric ceramic (PZT) and epoxy resin, respectively. The effects of thickness and volume fraction of PZT ceramic on piezoelectric, dielectric, and acoustic properties of the composites were discussed. The results showed that the piezoelectric strain constant, relative permittivity (ε33T), thickness electromechanical coupling coefficient (kt), mechanical quality factor (Qm) and acoustic impedance of the composites exhibit an increasing trend with the increase of the volume fraction of the PZT ceramics, while the piezoelectric voltage constant (g33) showed a decreasing trend. In the low frequency range of 60−90 kHz, the planar resonance peaks can be observed in the impedance-frequency spectra, while in the high frequency range of 2−6 MHz, there only exist clear thickness resonance peaks. With increasing the PZT volume fraction, the bandwidth of the thickness vibration mode of the piezoelectric fiber composites under the same thickness increases gradually. When the PZT volume fraction keep unchanged, the thickness resonance frequency of the composites increases with decreasing the thickness as well as the bandwidth of the thickness vibration mode, which is conducive for improving the frequency response range of the ultrasonic transducer made of the proposed piezoelectric fiber composites.