【作者】 徐玲芳；

【导师】 陈文；

【作者基本信息】 武汉理工大学 ， 材料学， 2006， 博士

【摘要】 1-3型压电陶瓷／聚合物复合材料兼具压电陶瓷的压电活性和聚合物的柔韧性。与单相压电材料及压电聚合物相比，具有较高的压电应变常数和厚度机电耦合系数、低的机械品质因数和声阻抗，适合制作高灵敏度、宽带、窄脉冲的换能器，是医疗超声、无损探伤和水听器的理想材料。 本文在分析1-3型压电复合材料研究现状的基础上，针对其在医疗超声换能器上的应用，采用塑性聚合物方法、排列-浇铸法，系统地研究了成型工艺、极化参数、压电陶瓷体积含量及纵横比等因素对1-3型压电复合材料的压电、介电、铁电性能和声阻抗的影响，并基于复合理论，研究了材料的相关规律，得到了实验与理论相吻合的研究结果，为这类材料的应用和开发提供了重要的理论依据。具体工作及结论如下： (1) 采用塑性聚合物方法分别制备了截面为圆形和方形的PZT5陶瓷纤维，分析了泥料中有机物含量、烧成条件对纤维结构与性能的影响。结果表明，最优化泥料配方为PZT5：PVA粘合剂：丙三醇=30：4：1(wt％)，最佳烧成温度为1280℃，保温时间为4h。PZT5陶瓷纤维结构致密，晶粒大小均匀，约2～5μm。 (2) 圆柱形PZT5纤维的吸水率W_a、显气孔率P_a和体积密度ρ_v分别为0.45％、0.44％和7.89g／cm~3。抗拉伸强度U．T．S．可达24.88MPa。剩余极化P_r与矫顽场E_c分别为41.40μC／cm~2和1.10kV／mm。方形PZT5纤维的体积密度ρ_v、抗拉伸强度U．T．S．、剩余极化P_r和矫顽场E_c分别为7.91g／cm~3、23.97MPa、41.68μC／cm~2和1.10kV／mm。 (3) 环氧树脂的固化工艺表明，采用顺丁烯二酸酐为固化剂时可获得结构致密、几乎无气孔的环氧树脂。1kHz下，环氧树脂的相对介电常数ε~*和介电损耗tanδ分别为3.81和3％，且在0～10MHz范围内变化不大。极化工艺对1-3型压电复合材料的性能有较大的影响，最佳极化工艺参数为极化时间30min，极化温度100℃，极化电压2.5kV／mm左右。采用排列-浇铸法可实现PZT5纤维的非周期性分布排列。 (4) 陶瓷体积含量φ对1-3型压电复合材料的性能有较大影响，性能的变化规律可以归纳为：随着陶瓷相含量φ的增加，1-3型压电复合材料的介电常数(?)几乎线性增加；剩余极化强度P_r显著增大，当φ为85％时，剩余极化强度P_r高达31.88μC／cm~2；压电应变常数(?)随着φ的增加而增大，其压电电压系数(?)比PZT5陶瓷大，随φ的增加而减小；径向机电耦合系数(?)比PZT5更多还原

【Abstract】 1-3 piezoelectric composites combine high piezoelectric properties of piezoelectric ceramic and flexibility of polymer. Compared with pure ceramic or piezoelectric polymer, 1-3 piezoelectric composites have more marks, such as higher piezoelectric conatant, larger mechanical-electronical coupling coefficient, lower mechanical quanity factor and smaller acoustic impedance. They are suitable for transducers with high sencsitivity, wide bend and narrow pulse, which have been widely used in medical ultrasonic, nondestructive test and hydrophone.In this article, the development of 1-3 composites was discussed. PZT5 fibers were fabricated by viscous polymer processing (VPP). 1-3 piezoelectric composites were prepared by arranging PZT5 fibers and casting epoxy resin. Based on its use for medical ultrsonic transducer, the influences of procedure, poling, ceramic volume fraction and aspect ratio on piezoelectric properties, dielectric properties, ferroelectric properties and acoustic impedance were studied. And the rules of 1-3 composites were consistent with the composite theory, which were useful for their applications and developments.(1) PZT5 ceramic fibers were fabricated by viscous polymer processing (VPP). The affects of organic and sintering condition on fiber structures and properties were analyzed. The optimized composition of lurry was 30 vs. 4 vs. 1 (PZT5 vs. PVA binder vs. glycerine, wt%), and the best sintering condition was done at 1280 °C for 4 h. The fiber structure was dense, and the crystal size was uniform, about 2-5 μm.(2) To the round section PZT5 fibers, the hygroscopic coefficient W_u, apparent porosity P_a and bulk density ρ_y were 0.45%, 0.44% and 7.89 g/cm~3, respectively. The ultimate tensile strength (U.T.S.) reached 24.88 MPa. The remnant polarization P_r and coercive field E_c were 41.40 μC/cm~2 and 1.10 kV/mm, respectively. The square section PZT5 fibers were fabricated with bulk density ρ_v of 7.91 g/cm~3. The U.T.S. was 23.97 MPa. While the value of P_r and E_c were 41.68 μC/cm~2 and 1.10 kV/mm, respectively.(3) With study on curing technique of epoxy resin, it was found that the structure of epoxy resin was tight and almost had no pore when the curing agent更多还原