CERAMIC-POLYMER COMPOSITE-MATERIALS FOR UNDERWATER DISTANCE SENSOR

The piezoelectric composite materials were made with PZT ceramics and epoxy polymer. The processing technique of the composite materials was the extrusin method, and the connectivity pattern of the two phase was the 1-3 type. Then PZT rods were extruded, dried on the vacuum chamber. For sintering, the PZT rods were cut into 4 cm length, PZT rods were sintered at 1270 degrees C. The PZT rods were aligned in the two racks, and it was under vacuum condition while the epoxy was poured into the plastic tube. The composites was cured at 70 degrees C for 8 hours, it was sliced by the diamond saw. The air-dried sliver paste was adhered and the materials were poled in a 80 degrees C oil bath with a DC electric field of 2 KV/mm for 10 minutes. As a experimental result, the electromechanical coupling coefficient (k(t)) of the materials was more than 0.65, and the resonance frequency of thickness vibration mode was 0.6 to 1.4 [MHz]. Acoustic impedance of the materials was 5.8-7.2 x 10(6) [kg/m(2)s]. The ultrasonic transducer using the PZT ceramics-epoxy polymer composites was manufactured, and it was known that the experimental result of measuring the underwater distance using the ultrasonic transducer was in good agreement with the actual measurement value. Therefore, the results demonstrate that the PZT-epoxy piezoelectric composite materials be possibility for underwater distance sensor.