| Résumé | Flexible ultrasonic transducers (UTs) consisting of a metal foil, a piezoelectric ceramic film and a top electrode have been developed. The flexibility is realized owing to the porosity of piezoelectric film and the thinness of metal foil. In this paper, the stainless steel, lead-zirconate-titanate (PZT)/PZT composite and silver paste were chosen as metal foil, piezoelectric film and top electrode materials, respectively. The stainless steel foil serves as both substrate and bottom electrode. The PZT/PZT piezoelectric composite film is made by the sol-gel spray technique. PZT/PZT films of thicknesses from 40 to 70 µm were fabricated onto SS foils. The capability of these flexible sensors operated in the pulse/echo mode for non-destructive testing on flat and curved surfaces of different materials at room temperature and 160°C has been demonstrated. Simulations of the effects of the metal foil thickness on the ultrasonic performance of flexible UTs were also carried out, and the results are in resonable agreement with experimental data. In addition, the PZT/PZT piezoelectric film UTs deposited onto a long steel buffer rod delay line showed a signal strength comparable with that obtained by commercial room temperature narrow bandwidth UTs. |
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