【作者】 刘晓芳；

【导师】 熊传溪；

【作者基本信息】 武汉理工大学 ， 材料学， 2005， 博士

【摘要】 具有良好柔韧性的压电复合材料因其兼有压电陶瓷和聚合物两相的优点,受到越来越多的关注。本文在分析压电复合材料研究现状的基础上,针对其在水声材料的应用,系统地研究了成型工艺、极化参数、压电陶瓷相、聚合物相以及聚合物掺杂等因素对0-3型复合材料的压电、介电、铁电性能和声阻抗的影响规律,揭示了极化的机制,确定了最佳的组分。我们发现锆钛酸铅/纳米晶聚氯乙烯（PZT/PVC）压电复合材料的综合性能优于传统上被认为最好的锆钛酸铅/聚偏氟乙烯（PZT/PVDF）压电复合材料,为水声探测器提供了一种全新的材料。 （1） 采用微波成型、热压机成型和冷压机成型三种成型工艺制备了PZT/PVDF压电复合材料,研究发现微波成型工艺制备的复合材料界面粘结最好,热压机成型工艺次之,冷压机成型工艺最差。其中微波成型工艺是在国内外首次采用,如果能解决设备问题,将在复合材料的制备上具有很大的应用前景。 （2） 通过极化工艺参数研究,发现极化电场强度、极化温度和极化时间都对复合材料的性能有较大的影响。对PZT/PVDF压电复合材料,适宜的极化时间为30min,极化温度为80～100℃,极化电压为10-15kV/mm。 （3） 随着陶瓷含量的增大,聚合物基压电复合材料的介电、压电和铁电性能都呈现非线性增大。当陶瓷含量到50%以后,0-3（1-3）混合连通形式的形成引起复合材料剩余极化强度的增大、矫顽场降低。同时,也造成复合材料密度ρ、声阻抗Z迅速增大。 （4） 随着陶瓷颗粒粒度的增大,复合材料的压电应变常数d₃₃、介电常数ε_r、机电耦合系数K_p和K_t等增大,声阻抗和机械品质因素Q_m降低,压电电场常数g₃₃的基本不变。随着陶瓷粒度的增大,复合材料的剩余极化强度(P_r增高,矫顽场（E_c）降低,陶瓷相更易极化。陶瓷粒度高于325目后,容易加工成大面积的薄膜。陶瓷粒度均匀分布有利于提高复合材料的综合性能。 （5） 采用高温热处理PZT陶瓷粉末。DSC和XPS测试表明,高温热处理后,PZT陶瓷粉末表面能降低,晶粒表面微结构优化。经高温热处理后的PZT陶瓷粉末制备的复合材料相对密度高,颗粒分布均匀,复合材料的综合性能好,声阻抗基本不变。 （6） 选用了三种热塑性聚合物为基体,采用热压工艺制备了三个体系的PZT/更多还原

【Abstract】 Combining a piezoelectric ceramic and a polymer matrix to form a flexible composite with coupling properties in between that of two individual phases has received much attention. The developing trend of piezoelectric composites has been reviewed in this paper. And the influence of the molding technique, poling condition, piezoelectric ceramic, polymer and additive on the piezoelectric, dielectric, ferroelectric properties and the acoustic impedances of 0-3 piezoelectric composites are investigated systemically. The mechanism of polarization is explained and the optimal constitute is confirmed in terms of experimental results. It is found that the properties of PZT/PVC composites are better than that of PZT/PVDF composites, which is a noval material for the purpose of hydrophone applications.（1） The PZT/PVDF composites have been prepared by three kinds of molding technique, i.e., high-temperature-pressing, cold-temperature pressing and microwave irradiation technique. The results show that the composites prepared by microwave technique have the best interface, high-temperature-pressing technique secondly. The piezoelectric eomposites are prepared by microwave technique for the first time, not recorded by any reports. The microwave technique will have an enormous application, if the equipment could be perfected.（2） It is founded that the dielectric and piezoelectric properties of the PZT/polymer composites highly depend on poling field, temperature and time. Appropriate poling time is 30 min, poling temperature is 80¹00℃ and poling field is 10¹5 kV/mm.（3） The dielectric, piezoelectric and ferroelectric properties of PZT/polymer composites nonlinearly increase with the increase of PZT volume fraction. When the PZT volume fraction is larger than 50%, the composites show good properties. And the remanent polarization （P_r） of the composites increase rapidly and the coercive field （E_c） decrease because of 0-3（1-3） mixed connectivity pattern being formed. At the same time, the density and acoustic impendence （Z） of the composites increases rapidly.（4） With the increasing of PZT particle size, the piezoelectric strain constant d₃₃, dielectric constant ε_r electromechanical coupling coefficient K_p and K_t increase,mechanical quality Qm and Z decrease and the piezoelectric voltage constant g33 keeps constant. The P-E hysteresis loops show that Pr increases and Ec values decreases with larger PZT particle size. The smaller-ceramic-particle composites have high density and are easy to fabricate thin sheet with large area. The nearly monodispersed particle size of the piezoelectric ceramic particle is benefit to improve integrative properties of the composites.（5） When the PZT powders annealed at high temperature, the results of DSC and XPS measurement show that the surface energy of the high-temperature-treated PZT decreases and the crystal surfacial microstructure is optimized. The composites with the high-temperature-treated PZT powders are more homogeneous and dense. The composites have better dielectric, piezoelectric and ferroelectric properties, and its Z value is nearly independent of the treatment.（6） Three kinds of thermoplastic polymer have been used to prepare the PZT/polymer composites with hot-temperature-pressing technique. The results show that polymer matrix has much influence on the piezoelectric, dielectric, ferroelectric properties and acoustic impendence of the composites. The PZT/PVDF composites have higher eT and tg<!> values than that of the other composites. The saturate P-E hysteresis loops show that, the Ec values of PZT/PVDF composites are lower than that of the PZT/PVC composites, and the PZT ceramic in the PZT/PVDF composites is easy to be poled. The PZT/PVC composites using nanocrystalline PVC have higher g33 values than that of the PZT/PVDF composites. Compared in three systems, The optimized electric properties were obtained in 0.5PZT/0.5PVC composite, showing d33=l5 pC/N, g33=42.6 mV-m-N’1, Kp=0.226, Z=11.25xl06kg-s’1-m"2, which is flexible enough for mechanical process.（7） The effect of molding temperature on the propertied of the 0.5PVC/0.5PZT composites are investiged. The optimal electric properties have been obtained in 0.5PZT/0.5PVC composite at molding temperature being 150 °C, showing ex =45.66 , tg￡ = 0.0286,coupling agent can improves the PVC morphology, increase the the density and the properties of the composites. The composites with 0.5 wt% aluminate coupling agent have optimal electric properties.（9） The in situ PVC/PAn composites are prepared by aniline polymerizing in the presence of PVC powders in hydrochloric acid. The PAn/PVC composite prepared by in-site technique has lower conductivity than that of composite made by blend. The O.5PZT//PAn/(0.5-j9PVC composites using PAn/PVC composite made by in-site technique are prepared by hot^temperature-pressing technique. A small content PAn added with the composites improve the piezoelectric properties, the optimized electric properties can be obtained when/is 6 %.（10） The three-phase 0.5?ZT/jC/（0.5-J）?VC composites have been prepared by hot-temperature-pressing technique. The optimized electric properties has been obtained in 0.5PZT/0.005C/0.0495PVC composite, showing cfo=24.5 pC/N, g33= 55.8 mV-m-N"1, Kp=0.249, K,=0.245, Qw=19.66,更多还原