Simultaneous generation of longitudinal and shear ultrasonic waves: knowledge summary, PZT piezoelements manufacturing and experiments

Known ultrasonic transducers for simultaneous generation of longitudinal and shear waves are reviewed: quartz and lithium niobate crystals tilted CdS and ZnO films. A special attention is devoted to the rotated cuts of PZT piezoceramics, literature data theoretical background conclusions are analysed. Manufacturing technology of dual mode PZT transducers with different cut angles and thickness was developed. Reliable electrodes suitable for soldering are made chemically in electroless nickel (EN) plating bath. Nickel electrodes are additionally dectroplated with silver. Various types of PZT ceramics were successfully used. From impedance measurements longitudinal and shear resonances were determined for typical thicknesses 45-100 μm. The cut angle 36o for equal efficiency of both waves was experimentally determined. Operation of transducers soldered to the steel rods and measurement bodies of the certain geometry was investigated. Measurements were provided in a temperature range 20–160 oC. Axial load experiments up to 234 MPa were provided and corresponding linear dependencies were determined. Experiments showed good performance of developed dual mode PZT ultrasonic transducers.