2-2型精细结构压电复合物及其在高频换能器中的应用
发布时间：2018-08-03 08:52
【摘要】：基于压电材料的高频超声波换能器能够发射并接收短波脉冲并具有极佳的图像的空间分辨率,在医学影像以及无损探伤等领域应用广泛。具有精细尺寸(20μm)压电单元的2-2型压电复合物是一种理想的高频换能器用功能材料,具有声阻抗低,机电耦合系数高,机械强度高等一系列优势。此外,该复合物精细的压电单元尺寸可以有效地抑制侧向谐振对主振荡模式的干扰,从而提高换能器的信噪比。近净成形技术可以制备无缺陷的精细压电单元,但该技术存在的一个问题是烧结后压电单元的弯曲导致较差的结构均匀度,因此通过研究压电单元在近净成形中的弯曲机制,从而制备出结构精细、均匀的压电复合物具有重要的意义。 本文首先探讨了铌酸钠钾(KNN),铌镁酸铅钛酸铅(PMN-PT)与锆钛酸铅(PZT)三种常用压电体系的合成与性能。采用固相法合成了高纯铌酸钠钾(KNN)系压电粉体。Li、Ta、Sb掺杂显著的提高了KNN系压电陶瓷的性能,随着Ta含量的提高,KNN的压电性能得到提高。采用熔盐法合成了高纯铌镁酸铅钛酸铅(PMN-PT)粉体,在有效抑地制焦绿石相形成的同时,显著地缩短了合成时间。 通过近净成形技术制备了精细结构2-2型压电复合物,并研究了压电单元的变形机制。聚合物软化是近净成形中导致压电单元变形的主要因素。采用惰性气氛脱酯可以有效地抑制压电单元的变形,从而使获得的压电单元尺寸可以达到20μm,并具有±2μm的精度误差。 研究了压电复合物结构域性能的关系。随着压电单元高径比的提高,复合物的机电耦合系数先增高再降低。对PZT基压电复合物而言,在高径比为3.5时,机电耦合系数最高达到0.61。压电相体积分数对复合物性能的影响并不显著,提高压电相体积分数,复合物的性能有一定程度的下降。 将PZT基2-2型精细结构压电复合物封装为高频换能器,并进行脉冲-回波测试。结果表明,基于2-2型精细结构压电复合物的高频换能器中心频率达到23.09MHz,带宽达到5.5MHz。图32幅,表7个,参考文献63篇。
[Abstract]:High frequency ultrasonic transducers based on piezoelectric materials can transmit and receive short wave pulses and have excellent spatial resolution of images. They are widely used in medical images and nondestructive flaw detection. The 2-2 piezoelectric composite with fine size (20 渭 m) piezoelectric element is an ideal functional material for high frequency transducer. It has a series of advantages such as low acoustic impedance, high electromechanical coupling coefficient and high mechanical strength. In addition, the fine piezoelectric element size of the composite can effectively suppress the interference of the lateral resonance to the main oscillation mode, thus improving the signal-to-noise ratio (SNR) of the transducer. Near-net forming technology can fabricate fine piezoelectric elements without defects, but one of the problems in this technology is that the bending of the sintered piezoelectric elements leads to poor structural uniformity, so the bending mechanism of piezoelectric elements in near-net forming is studied. It is of great significance to prepare fine and homogeneous piezoelectric composites. In this paper, the synthesis and properties of (KNN), lead titanate (PMN-PT) and lead zirconate titanate (PZT) are studied. The high purity sodium and potassium niobate (KNN) system piezoelectric powder 路Li-TaTa-Sb doped with high purity sodium and potassium niobate was synthesized by solid state method. The properties of KNN system piezoelectric ceramics were greatly improved by doping. The piezoelectric properties of KNN system were improved with the increase of Ta content. Lead magnesium niobate titanate (PMN-PT) powder was synthesized by molten salt method. The fine structure 2-2 piezoelectric composites were prepared by near-net forming technique and the deformation mechanism of piezoelectric elements was studied. Polymer softening is the main factor leading to deformation of piezoelectric element in near net forming. The deesterification in inert atmosphere can effectively suppress the deformation of the piezoelectric element, and the size of the obtained piezoelectric element can reach 20 渭 m, and the precision error of 卤2 渭 m can be obtained. The relationship between the domain properties of piezoelectric composites was studied. With the increase of the aspect ratio of piezoelectric elements, the mechatronic coupling coefficient of the composite increases first and then decreases. For PZT based piezoelectric composites, the maximum electromechanical coupling coefficient is 0.61when the aspect ratio is 3.5. The effect of the piezoelectric phase volume fraction on the properties of the composites is not significant. The performance of the composites decreases to a certain extent when the piezoelectric phase volume fraction is increased. The PZT based 2-2 fine structure piezoelectric composite was encapsulated into a high frequency transducer and the pulse echo was measured. The results show that the center frequency of high frequency transducer based on 2-2 fine structure piezoelectric composite is 23.09 MHz and the bandwidth is 5.5 MHz. There are 32 pictures, 7 tables and 63 references.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB33;TB552
本文编号：2161232
[Abstract]:High frequency ultrasonic transducers based on piezoelectric materials can transmit and receive short wave pulses and have excellent spatial resolution of images. They are widely used in medical images and nondestructive flaw detection. The 2-2 piezoelectric composite with fine size (20 渭 m) piezoelectric element is an ideal functional material for high frequency transducer. It has a series of advantages such as low acoustic impedance, high electromechanical coupling coefficient and high mechanical strength. In addition, the fine piezoelectric element size of the composite can effectively suppress the interference of the lateral resonance to the main oscillation mode, thus improving the signal-to-noise ratio (SNR) of the transducer. Near-net forming technology can fabricate fine piezoelectric elements without defects, but one of the problems in this technology is that the bending of the sintered piezoelectric elements leads to poor structural uniformity, so the bending mechanism of piezoelectric elements in near-net forming is studied. It is of great significance to prepare fine and homogeneous piezoelectric composites. In this paper, the synthesis and properties of (KNN), lead titanate (PMN-PT) and lead zirconate titanate (PZT) are studied. The high purity sodium and potassium niobate (KNN) system piezoelectric powder 路Li-TaTa-Sb doped with high purity sodium and potassium niobate was synthesized by solid state method. The properties of KNN system piezoelectric ceramics were greatly improved by doping. The piezoelectric properties of KNN system were improved with the increase of Ta content. Lead magnesium niobate titanate (PMN-PT) powder was synthesized by molten salt method. The fine structure 2-2 piezoelectric composites were prepared by near-net forming technique and the deformation mechanism of piezoelectric elements was studied. Polymer softening is the main factor leading to deformation of piezoelectric element in near net forming. The deesterification in inert atmosphere can effectively suppress the deformation of the piezoelectric element, and the size of the obtained piezoelectric element can reach 20 渭 m, and the precision error of 卤2 渭 m can be obtained. The relationship between the domain properties of piezoelectric composites was studied. With the increase of the aspect ratio of piezoelectric elements, the mechatronic coupling coefficient of the composite increases first and then decreases. For PZT based piezoelectric composites, the maximum electromechanical coupling coefficient is 0.61when the aspect ratio is 3.5. The effect of the piezoelectric phase volume fraction on the properties of the composites is not significant. The performance of the composites decreases to a certain extent when the piezoelectric phase volume fraction is increased. The PZT based 2-2 fine structure piezoelectric composite was encapsulated into a high frequency transducer and the pulse echo was measured. The results show that the center frequency of high frequency transducer based on 2-2 fine structure piezoelectric composite is 23.09 MHz and the bandwidth is 5.5 MHz. There are 32 pictures, 7 tables and 63 references.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB33;TB552
【共引文献】
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