FABRICATION OF ULTRASONIC TRANSDUCERS WITH PZT

We mixed PbO, ZrO2, TiO2, Nb2O5 and MnCO3 to make Pb[(Zr0.54Ti0.46)Nb- 0.005]O-3 + 4%MnCO3. The electroded PZT ceramics were poled by 3 kV/mm field at 110 degrees C for 600 s. We assembled the 0.4 mm thick PZT s lices into ultrasonic transducers. Central frequency of the probe is 5 MHz, which is proper to the thickness gauge for steel pipes and for f law detector. The probe can detect a disk shape defect of 1 mm diamete r at 15 cm deep in steel block. The new probe's Fresnel zone that the ultrasonic beam does not broaden is 13 mm. Over the Fresnel zone, the ultrasonic beam spreads. Half of the beam spread angle of the probe is 4.3 degrees - 4.6 degrees. This probe is adequate to the thickness ga uge for steel pipes and the flaw detector for welded steel plates.