Design,Preparation And Characterization Of PZT-based Piezoelectric Composite Aerogel

As the most widely used piezoelectric material,lead zirconate titanate has the advantages of high piezoelectric effect,good stability and mutual conversion of mechanical signals and electrical signals.However,for the underwater acoustic transducer,its bulk density(~7.6g/cm~3),high acoustic impedance,high brittleness,and poor compatibility with air and water media impedance are important issues that cannot be ignored.The very low density of aerogel is easy to achieve acoustic impedance matching with air,water and organisms.It is very suitable for the needs of underwater acoustic transducers.Based on this background,the thesis conducts a research about the preparation process of lead zirconate titanate aerogel and its composite materials.(1)Firstly,lead zirconate titanate was prepared by modified sol-gel method using ethylene glycol methyl ether as solvent,lead acetate trihydrate as lead source,zirconium n-propoxide and tetrabutyl titanate as zirconium source and titanium source,respectively.A wet gel was prepared and a lead zirconate titanate aerogel was prepared by supercritical drying.The effects of different process parameters and heat treatment temperature on the properties of the samples were studied and the materials were characterized by SEM,BET,XRD and FT-IR.It has been found that the addition of propylene oxide can shorten the gel time,and the aerogel specific surface area increases first and then decreases as the propylene oxide content increases.Different heat treatment temperatures have a significant effect on the structure of lead zirconate titanate.The heat treatment above550°C can completely convert the sample into PZT of perovskite phase.(2)The composite aerogels of Lead zirconate titanate and polyvinylidene fluoride were prepared by sol-gel method.The density of the composite aerogel is between 0.18and 0.24 g/cm~3.XRD results indicate that the structure of the aerogel is amorphous.Scanning electron microscopy showed that all PZT particles were grown on the flexible PVDF network skeleton nanostructures.The specific surface area is between 129 and 179m~2/g,and the pore size is mainly distributed between 8 and 30 nm.The PVDF content has a greater influence on the surface area,but the effect on the pore size distribution is not obvious.Water and PVDF content have no effect on pore size.The XPS results show that the surface composition contains Pb,Zr,Ti,O,C,and F,which is consistent with the precursor.(3)Using PVDF as the matrix,PZT/PVDF composite aerogel coating was prepared by mixing PZT aerogel with binder as slurry.The characterization and test results of different heat treatment samples show that the composite aerogel coating heat-treated in the temperature range of 550°C-600°C has good flexibility and is far lower than the density and good electrical properties of ordinary ceramics.