Research On Deposition And Direct Writing Process Of PZT Piezoelectric Micro Structures

PZT thick films and PZT three-dimensional piezoelectric micro structures have broad application prospects in the fields of aeronautics and astronautics,biomedicine,and information and communication due to their excellent piezoelectric and mechanical properties.Electrohydrodynamic jet deposition technology is an important method for additive manufacturing of micro/nano-scale structures,which has the advantages of strong controllability,high forming resolution and wide material adaptability.The direct ink writing technology is a solid freeform fabrication technique at room temperature,and the preparation of the three-dimensional structure is achieved by controlled deposition of a fluid slurry on a substrate.In this paper,the PZT piezoelectric micro structure deposition/direct writing forming experimental platform was constructed,and the preparation process of PZT thick film and PZT three-dimensional piezoelectric micro structure was integrated.PZT composite suspension and PZT slurry were prepared.The electrohydrodynamic jet deposition of PZT thick film functional layer of piezoelectric micro cantilever and direct writing forming of three-dimensional piezoelectric micro structure were carried out,respectively.In addition,according to the phenomenon of PZT thick film heat treatment experiment,a bulk PZT/silicon diffusion bonding method was proposed and experimentally studied.Firstly,the PZT piezoelectric micro structure deposition/direct writing forming experimental platform was designed and constructed to ensure the effective and simple adjustment of deposition height,flow rate,voltage and other parameters in the PZT electrohydrodynamic jet deposition experiment.By replacing the needle,different experimental requirements for PZT electrohydrodynamic jet deposition and PZT direct writing forming can be satisfied.The software for PZT piezoelectric micro structure deposition/direct write forming experimental platform was developed to achieve coordinated control of X-Y axis motion platform,Z axis motion platform and syringe pump.Secondly,the effects of annealing temperature and annealing time on the crystallographic phase and micro structure of PZT thick film on silicon substrate were studied,and the appropriate annealing process parameters were determined.The bulk PZT/silicon high-temperature treatment experiment was conducted and the bulk PZT/silicon diffusion bonding method was proposed.The bulk PZT/silicon diffusion bonding fixture was designed and fabricated.The influence of bonding temperature and bonding time on the quality of bulk PZT/silicon diffusion bonding was studied,and the thickness of the bonding layer under different experimental conditions was characterized.Then,PZT sol and PZT composite suspension suitable for template-assisted electrohydrodynamic jet deposition process were prepared and characterized.Based on the prepared PZT suspension,the PZT thick film functional layer of piezoelectric micro cantilever was fabricated by electrohydrodynamic jet deposition technology and then polarized.The piezoelectric properties and dielectric properties of the PZT thick film and the impedance characteristics of the piezoelectric micro cantilever were characterized.The piezoelectric constant d33,relative permittivity and dielectric loss at 50 kHz of the PZT thick film were 70 pC/N,198 and 0.053,respectively,and the maximum resonant frequency of the piezoelectric micro cantilever was 7.6 MHz.Finally,the PZT slurry suitable for the direct writing process was prepared and characterized.Based on the prepared PZT slurry,the three-dimensional piezoelectric structures of circular wall,square disk and square scaffold were prepared by the direct writing process.The effects of different holding time on the micro structure of the prepared square bulk PZT piezoelectric structure under the annealing temperature of 1200 °C were investigated,and the suitable annealing holding time was determined.The prepared square bulk PZT piezoelectric structure was polarized and its piezoelectric properties and dielectric properties were characterized.The piezoelectric constant d33,relative permittivity and dielectric loss at 50 kHz of the square bulk PZT piezoelectric structure were 200 pC/N,1200 and 0.13,respectively.