Preparation And Properties Of Piezoelectric Ceramic Interfacial Bond

Spherical transducers are widely used in underwater acoustic field because of their advantages such as simple mechanical structure,easy array shape and full directivity.As the core functional element of spherical transducer,piezoelectric ceramic spheres are bonded by epoxy resin.The physical and chemical properties of epoxy resin are very different from those of piezoelectric ceramic,which leads to the problems of brittle,poor heat resistance,poor mechanical properties and not consistent with the electrical properties of piezoelectric ceramic spheres.Due to the poor thermal and mechanical stability of epoxy resin bonding interface,the piezoelectric ceramic hemisphere is debonded at the interface,which leads to the failure of spherical transducer.In order to solve the above problems,the composition system of inorganic interface binder was designed,the low temperature sintering process suitable for piezoelectric ceramics was discussed,and the mechanical and electrical properties of the bonded interface were systematically studied.The main research contents are as follows:The influence of glass powder size on softening temperature was studied systematically,the influence of different dispersants and content on bonding effect of interfacial bond was clarified,and a system of interfacial bond was established.The results showed that the softening temperatures of three kinds of glass powders showed a decreasing trend with the particle size decreasing from 6.0μm to 2.5μm and below,and the decreasing amplitude was more than 126℃.When terpinol was used as dispersant,the viscosity of interfacial bond and the bonding strength of piezoelectric ceramics were better than that when anhydrous ethanol and PVA aqueous solution were used as dispersant.The viscosity of interfacial binder increases gradually with the increase of solid-liquid ratio m _PZT+glasspowder/m_terpineolWhen the solid-liquid ratio is 2:1,PZT particles and glass powder can form uniform dispersion in terpineol,and the viscosity of interfacial binder reaches the optimal value of 520 m Pa·s.The effects of interfacial bond and sintering system on the bonding properties of piezoelectric ceramics were studied,and the electrical and mechanical properties of the bonded piezoelectric ceramics were systematically analyzed.The results show that:When the sintering temperature is 750℃and the PZT particle content is 10 wt%,the interface binder forms a uniform and dense interface layer between the piezoelectric ceramics.At this time,the piezoelectric coefficient of the piezoelectric ceramics is 223 p C/N,and the bending strength is 74.89 MPa.Compared with epoxy resin bonded piezoelectric ceramics,46.13%and 1.04 times higher,respectively.With the increase of aging time and temperature,the electrical properties of the piezoelectric ceramics bonded by epoxy resin decrease greatly.When the temperature increases to 230℃,the epoxy resin fails and the bonding surface cracks.However,the piezoelectric coefficient of piezoelectric ceramics prepared by interfacial bond is only reduced by 9.0%,showing good time and temperature stability.Piezoelectric ceramic spheres were fabricated by interfacial bond,and spherical piezoelectric transducers were further fabricated by encapsulation.The effects of different bonding interfaces on electrical properties of spherical transducers were investigated.The results show that:With epoxy resin adhesive,compared to the piezoelectric ceramic ball and spherical transducer using the interface bonding agent of the conductance of the piezoelectric ceramic ball increased 0.01 S,corresponding to the bandwidth of the transducer increased1.10 k Hz,and adhesive interface with piezoelectric ceramic forming coherent vibration transducer with single resonance peaks,show the better performance of electromechanical coupling.