【作者】 杨雄；

【导师】 周静；

【作者基本信息】 武汉理工大学 ， 材料学， 2008， 硕士

【摘要】 1．3型压电纤维/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，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、无损探测和水声换能器的理想材料。针对环境协调性和1-3型压电复合材料在医疗超声换能器上的应用和要求，采用塑性聚合物方法制备了KNBT压电纤维，通过排列-浇注法制备了1-3型压电复合材料，系统研究了复合材料中压电相的排布方式和性能之间的相关性，探讨了纤维含量及长径比对复合材料性能的影响，获得压电复合材料性能变化规律。具体工作及结沦如下：1、采用塑性聚合物方法制各了KNBT压电纤维，分析了泥料的固含量和烧成条件对纤维结构与性能的影响。结果表明，当陶瓷固含量为83．3wt％时，可获得可塑性较好、有一定强度的压电纤维素坯。经过1100℃处理2h，KNBT纤维的结构致密、晶粒大小均匀，吸水率W_a、显气孔率P_a和体积密度p_v分别为0．45％、0．46％和5．94g．cm^-3，抗拉伸强度可达20．52MPa。2、采用排列-浇注法制备了1-3型压电复合材料，对复合材料的固化工艺和极化条件进行了研究。结果表明，环氧树脂基体：固化剂：塑性剂：促进剂（质量百分比）：100：85：5：0．3，固化温度为160℃时，固化效果较好。极化电场强度为3kV．mm^-1，极化时间为30min，极化温度为80℃时，复合材料有较好的介电和压电性能。3、纤维体积含量对1-3型压电复合材料的性能有较大影响，随着纤维体积含量φ的增加，1-3型压电复合材料的介电常数（?）线性增加，剩余极化强度Pr和压电常数（?）显著增大，当φ=85％时，剩余极化强度Pr=29．40μC．cm^-2；压电常数（?）=74pC．N^-1。4、纤维长径比t/d对1-3型压电复合材料的各项性能均产生大的影响。随t/d的增加，介电常数（?）和介电损耗tanδ均减小。压电应变常数（?）和压电电压系数（?）均随着t/d的增加而增大，且（?）比KNBT陶瓷大。更多还原

【Abstract】 1-3 piezoelectric composites combine the high piezoelectric properties of piezoelectric ceramic and the flexibility of polymer. Thus 1-3 piezoelectric composites have more merits, such as higher piezoelectric constant, larger electro-mechanical coupling coefficient, lower mechanical quality factor and smaller acoustic impedance. They are suitable for transducers with high sensitivity, broad and narrow pulse, which have been widely used in medical ultrasonic, non-destructive testing and acoustic transducers.For the environmental harmony and applications of 1-3 piezoelectric composites to medical ultrasonic transducer. KNBT piezoelectric fibers were fabricated by viscous polymer processing （VPP） and 1-3 type piezoelectric composites were prepared by arrangement-pouring method. The interrelation of composites among arrangements and properties were studied systematically . And the effects of different composition and volume fraction of piezoelectric fibers on the composites properties were discussed. The concrete work and conclusions as follows.1、KNBT ceramic fibers were fabricated by viscous polymer processing （VPP）. The affects of organic content and sintering condition on fiber structures and properties were analyzed. The results show that solid content is 83.3wt%,the green fibers with fine slasticity and strength were prepared.and the best sintering condition was done at 1100℃for 2h. To the KNBT fibers, the hygroscopic coefficient Wa, apparent porosity Pa and bulk density pv were 0.45%, 0.46% and 5.94g/cm³, respectively. The ultimate tensile strength reached 20.52 MPa.2、1-3 piezoelectric composites achieved by arranging-casting technique. With study on curing technique of epoxy resin, The optimized composition of epoxy resin was 100 vs. 85 vs. 5 vs. 0.3 （epoxy resin E-51 vs. MTHPA vs. DOP vs. DMP-30, wt%）, The electric field, temperature and time during poling dramatically influenced the properties of 1-3 composites. The optimal poling condition was processed on time of 30 min, temperature of 80℃, and electric field of 3 kV.mm^-1.3、The fiber volume fractionφhad prodigious effects on properties of 1-3 composites. With increasing the ceramic volume fraction, the relative permittivity constant （?） of 1-3 composites rose linear, and remnant polarization gained prominently. The piezoelectric strain constant （?） increased with increasing of fiber volume fractions and the piezoelectric voltage constant （?） decreased.When thefiber volume fractionφreached 85%,the remnant polarization P₁ and piezoelectric strain constant （?） were 29.40μC.cm^-2 and 74pC.N^-1.4、The influences of aspect ratio t/d on properties of 1-3 composites were tremendous. As increasing t/d, the relative permittivity constant （?） and permittivity loss tanδwill reduce. At the same time, the piezoelectric strain constant （?） and piezoelectric voltage constant （?） will increase. And the values of （?） were higher than KNBT ceramic all through.更多还原