Research On1-3Piezoelectric Composite And Transducer

Underwater sound transducers play a very important role in the sonar system. And theproperties of the transducers are seriously affected by the transduction materials.1-3piezoelectric composites have been widely recognized as excellent impedance matching withwater, thickness electromechanical coupling performance and design freedom. And theunderwater sound transducer made in it has some virtues such as wider working band, hig_hersensitivity and pure thickness mode. So1-3piezoelectric composites must enjoy an extendeddevelopment prospect in some areas of underwater.In this paper the1-3polymer-based piezoelectric composites were fabricated usingepoxy as matrix by the cut-filling method. The influences of the ceramic volume fraction, theunit cross-sectional area and the aspect ratio on the1-3properties of piezoelectric compositeswere studied, respectively. The results indicate that with increasing the ceramic volumefraction, both the hydrostatic piezoelectric voltage g_hand hydrostatic figures of merit d_h·g_hofthe composite decrease, while the relative dielectric constant εrincreases. The hydrostaticpiezoelectric strain d_hhas the optimum value in the volume fraction range of40%-60%.Quality factor changes little; With the increase of the unit cross-sectional area, the Q_mincreases while the d_hdecrease. Both the hydrostatic piezoelectric voltage g_hand d_h·g_hincreases and then goes down rapidly. The planar electromechanical coupling factor kpchanges little; The thickness electromechanical coupling factor kt, g_h, hydrostatic sensitivityMhand the d_h·g_hvalues are all decreased rapidly as the w/t increases, while the quality factorvalue decreases as the w/t increases. A summary of the results is show that in the volumefraction range of40%-60%, the smaller of unit cross-sectional area and thinner of thickness,the more helpful for sensitivity when it is used in transducer.Nickel films were deposited on the piezoelectric composites by the electroless Ni plating.The optimal process and formula conditions of pretreatment process, activation process andthe electroless plating solution were obtained in combination with the orthogonal test and thepractical production as follows,350g/L of mass concentration,25℃of roug_heningtemperature,25min of roug_hening time;0.4g/L of PdCl₂,30℃of activation temperature, 5min of activation time;38-43℃of plating temperature,8-10min of plating time and pHvalue of8.5-9.5; Nickel sulfate concentration of20g/L, sodium hypophosphite concentrationof23g/L, sodium citrate concentration of11.7g/L. The micro-morphology and compositionsof piezoelectric composites deposit were analyzed and compared by using SEM, EDS andXRD analysis. The deposit ad_hesion and corrosion resistance were analyzed by using thermalshock test and polarization curve. The results show that the deposit of the optimal conditionshas well uniformity, and with good ad_hesion and corrosion resistance.The underwater transducer was developed by using1-3piezoelectric composites. Theinfluence of the matching layer, backing and packaging materials on the performance oftransducer was researched. The results indicate that, the matching layer can increasedreceiving sensitivity of transducer by90kHz. With the increase of the thickness of matchinglayer, the receiving response was increased firstly and then decreased，which had best propertyat the point of2.2mm. The fastest attenuation was epoxy resin-tungsten powder. Theinfluences of packaging materials on the performance of the transducer are small. Thebandwidth of underwater transducer for the final design was53kHz, These results supply thecredible theoretics bases for the practices.