CN101499512B

Movatterモバイル変換

Info

Publication number: CN101499512B
Application number: CN2009100787800A
Authority: CN
Inventors: 秦雷; 王丽坤; 李莉; 王钢; 张金铎
Original assignee: Beijing Information Science and Technology University
Current assignee: Beijing Information Science and Technology University
Priority date: 2009-03-03
Filing date: 2009-03-03
Publication date: 2010-10-06
Anticipated expiration: 2029-03-03
Also published as: CN101499512A

Abstract

Description

Translated fromChinese

宽带换能器的压电复合材料Piezoelectric composites for broadband transducers

技术领域technical field

本发明是关于压电材料及其器件技术，具体涉及到一种用于水声、超声探测的宽带换能器的压电复合材料。The invention relates to a piezoelectric material and its device technology, in particular to a piezoelectric composite material for a broadband transducer used in underwater sound and ultrasonic detection.

背景技术Background technique

压电复合材料主要应用于水声换能器和超声换能器两个方面。水声换能器是将声能和电能进行相互转换的器件，其地位类似于无线电设备中的天线，是在水下发射和接收声波的关键器件。水下的探测、识别、通信，以及海洋环境监测和海洋资源的开发，都离不开水声换能器。超声换能器主要用于医疗超声成像、无损检测等方面，原理与水声换能器相同，只是应用的频率比水声换能器高。Piezoelectric composite materials are mainly used in two aspects of underwater acoustic transducers and ultrasonic transducers. The underwater acoustic transducer is a device that converts sound energy and electrical energy into each other. Its status is similar to that of an antenna in radio equipment, and it is a key device for transmitting and receiving sound waves underwater. Underwater detection, identification, communication, as well as marine environment monitoring and the development of marine resources are inseparable from underwater acoustic transducers. Ultrasonic transducers are mainly used in medical ultrasonic imaging, non-destructive testing, etc. The principle is the same as that of underwater acoustic transducers, but the frequency of application is higher than that of underwater acoustic transducers.

目前常用的通过压电效应制作的换能器主要采用以下几种敏感材料：压电单晶、锆钛酸铅压电陶瓷以及压电复合材料。其中压电陶瓷和压电单晶由于Q值较高，并不适合制备宽带换能器，而压电复合材料虽然在Q值上有一定的降低，但是仍然不能满足现在水声换能器领域的需求。为此，申请人于2004年研发了一种基于串并联压电复合材料的器件(专利200410009179.3)，该器件采用的材料是在传统1-3型压电复合材料基础上并联了一个压电基底，使得复合材料结构在横向和纵向都有压电陶瓷骨架的支撑。兼有并联和串联压电复合材料的特点，性能稳定，在受热和外力冲击下不易变形，制作工艺简单，且由于该压电复合材料引入了聚合物相，使得复合材料的损耗增加，从而在一定程度上降低了Q值，但是，该压电复合材料的Q值仍在10以上，不能实现制备宽带换能器。At present, the commonly used transducers made by the piezoelectric effect mainly use the following sensitive materials: piezoelectric single crystal, lead zirconate titanate piezoelectric ceramics and piezoelectric composite materials. Among them, piezoelectric ceramics and piezoelectric single crystals are not suitable for the preparation of broadband transducers due to their high Q values. Although piezoelectric composite materials have a certain decrease in Q values, they still cannot meet the requirements of the current underwater acoustic transducer field. demand. To this end, the applicant developed a device based on series-parallel piezoelectric composite materials in 2004 (patent 200410009179.3). The material used in this device is a piezoelectric substrate connected in parallel on the basis of traditional 1-3 piezoelectric composite materials. , so that the composite structure has the support of the piezoelectric ceramic skeleton in the horizontal and vertical directions. It has the characteristics of both parallel and series piezoelectric composite materials, stable performance, not easy to deform under heat and external impact, simple manufacturing process, and because the piezoelectric composite material introduces a polymer phase, the loss of the composite material increases, so in The Q value is reduced to a certain extent, but the Q value of the piezoelectric composite material is still above 10, and the preparation of a broadband transducer cannot be realized.

发明内容Contents of the invention

本发明克服了现有技术中的不足，提供了一种用于制备宽带换能器的压电复合材料。The invention overcomes the deficiencies in the prior art and provides a piezoelectric composite material used for preparing broadband transducers.

本发明的技术方案是：Technical scheme of the present invention is:

一种宽带换能器的压电复合材料，包括压电晶体和聚合物，压电晶体分为上、下两部分，其中，上部结构为均匀排列的多个压电晶柱，下部结构为一压电基底，所述压电晶柱的高度呈周期性差异，使得压电基底厚度不均匀，聚合物填充在所述压电晶柱之间，所述压电晶柱及压电基底的极化方向沿着压电复合材料的厚度方向。A piezoelectric composite material for broadband transducers, including piezoelectric crystals and polymers, the piezoelectric crystal is divided into upper and lower parts, wherein the upper structure is a plurality of uniformly arranged piezoelectric crystal columns, and the lower structure is a The piezoelectric substrate, the height of the piezoelectric crystal pillars is periodically different, so that the thickness of the piezoelectric substrate is uneven, and the polymer is filled between the piezoelectric crystal pillars, and the electrodes of the piezoelectric crystal pillars and the piezoelectric substrate The orientation is along the thickness direction of the piezoelectric composite material.

压电晶柱的高度差异具有线性分布或高斯分布规律。The height difference of the piezoelectric crystal column has a linear distribution or a Gaussian distribution law.

每个压电晶柱的垂直于水平面的四个侧面的面积不相同。The areas of the four sides perpendicular to the horizontal plane of each piezoelectric crystal column are different.

晶柱的边长为0.3～5mm，每片晶柱的高度为0.5～15mm，相邻两个晶柱的高度不同，成周期性空间分布，每个周期内呈线性分布、高斯分布等，晶柱间的差值为0.1～5mm。The side length of the crystal column is 0.3-5mm, and the height of each crystal column is 0.5-15mm. The heights of two adjacent crystal columns are different, and they are distributed in a periodic space. Each period is linear, Gaussian, etc. The crystal The difference between columns is 0.1-5mm.

上述聚合物可以选择环氧树脂、聚氨酯、硅橡胶等粘接剂，聚合物固化后宽度为0.2～2mm。填充物可以根据不同的需求选择金属粉末或小颗粒、真空玻璃微球，其直径小于0.1mm，便于均匀添加于聚合物中并且能够灌注到切割形成的刀槽内。The above-mentioned polymer can be selected from adhesives such as epoxy resin, polyurethane, and silicon rubber, and the width of the polymer after curing is 0.2-2 mm. The filler can be selected from metal powder or small particles, vacuum glass microspheres according to different needs, and its diameter is less than 0.1mm, which is convenient to add evenly to the polymer and can be poured into the groove formed by cutting.

与现有技术相比，本发明的有益效果是：Compared with prior art, the beneficial effect of the present invention is:

本发明在申请人的专利(基于串并联压电复合材料的器件)基础上，通过改变压电晶柱间的高度差，既保持了压电体本身的高发射电压响应，大的机电耦合系数(60-70％)，同时，由于每个压电晶柱的谐振频率不同，增加了压电复合材料的宽带，本发明压电复合材料的Q值可以达到10以下，适用于制备宽带换能器。Based on the applicant's patent (device based on series-parallel piezoelectric composite materials), the present invention not only maintains the high emission voltage response of the piezoelectric body itself, but also maintains a large electromechanical coupling coefficient by changing the height difference between the piezoelectric crystal columns. (60-70%), at the same time, because the resonant frequency of each piezoelectric crystal column is different, the broadband of the piezoelectric composite material is increased, and the Q value of the piezoelectric composite material of the present invention can reach below 10, is suitable for preparing broadband transduction device.

附图说明Description of drawings

图1是本发明宽带压电复合材料结构示意图；Fig. 1 is the structure schematic diagram of broadband piezoelectric composite material of the present invention;

其中，1-压电晶柱；2-压电基底；3-聚合物；4-电极；Among them, 1-piezoelectric crystal column; 2-piezoelectric substrate; 3-polymer; 4-electrode;

图2是宽带压电复合材料中一个压电晶柱单元结构示意图；Fig. 2 is a structural schematic diagram of a piezoelectric crystal column unit in a broadband piezoelectric composite material;

图3是二级参差调谐效应示意图；Fig. 3 is a schematic diagram of the second-order stagger tuning effect;

图4是本发明实施例的试验结果示意图。Fig. 4 is a schematic diagram of test results of an embodiment of the present invention.

具体实施方式Detailed ways

下面结合附图和具体实施方式对本发明作进一步详细描述：Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

参考图1，本发明压电复合材料的压电晶柱均匀排列于压电基底之上，相邻的晶柱之间，填充有聚合物，而聚合物内又有填充物用来调节聚合物的性能；压电晶柱及压电基底的极化方向沿着复合材料的厚度方向；上、下电极由易焊接金属经沉积或烧结制成，上、下电极分别位于宽带压电复合材料的上下表面，构成宽带换能器压电元件。本发明压电复合材料中，在平行和垂直于极化方向均有硬质压电陶瓷支撑，且每个周期内的压电晶柱的高度具有线性分布或高斯分布规律，造成压电晶柱高度不同，压电基底厚度也不均匀，压电复合材料的厚度振动谐振频率的带宽较宽、机械Q值较小，一般可达到10以下。Referring to Fig. 1, the piezoelectric crystal pillars of the piezoelectric composite material of the present invention are evenly arranged on the piezoelectric substrate, and the adjacent crystal pillars are filled with polymers, and the fillers in the polymers are used to adjust the polymer. performance; the polarization direction of the piezoelectric crystal column and the piezoelectric substrate is along the thickness direction of the composite; The upper and lower surfaces constitute the piezoelectric element of the broadband transducer. In the piezoelectric composite material of the present invention, there are hard piezoelectric ceramic supports parallel to and perpendicular to the polarization direction, and the height of the piezoelectric crystal column in each period has a linear distribution or a Gaussian distribution law, resulting in piezoelectric crystal column With different heights, the thickness of the piezoelectric substrate is not uniform. The bandwidth of the resonance frequency of the thickness vibration of the piezoelectric composite material is wide, and the mechanical Q value is small, which can generally reach below 10.

本发明压电复合材料的压电晶柱的平行于z方向的四个侧面分别与聚合物相接触，采用了特殊切割工艺，四个接触面面积各不相同。如果设沿某一方向以n个压电晶柱为一个周期进行切割，那么在整个复合材料内将会产生n²/2种不同边界条件的压电晶柱，这些晶柱边界条件各不相同，因此这些晶柱的厚度振动模态的频率也就各不相同，并分布在一定的频率范围内。这些厚度振动模态的谐响应曲线叠加在一起就构成宽带压电复合材料的总体谐响应曲线，如图3所示。由于参差调谐效应拓宽了压电复合材料的带宽。The four sides of the piezoelectric crystal column parallel to the z direction of the piezoelectric composite material of the present invention are respectively in contact with the polymer, and a special cutting process is adopted, so the areas of the four contact surfaces are different. If cutting along a certain direction with n piezoelectric crystal columns as a cycle, n² /2 kinds of piezoelectric crystal columns with different boundary conditions will be produced in the whole composite material, and the boundary conditions of these crystal columns are different. , so the frequencies of the thickness vibration modes of these crystal columns are also different and distributed in a certain frequency range. The harmonic response curves of these thickness vibration modes are superimposed to form the overall harmonic response curve of the broadband piezoelectric composite material, as shown in Figure 3. The bandwidth of the piezoelectric composite is widened due to the stagger tuning effect.

下面对宽带非均匀基底压电复合材料的制备工艺进行详细说明。The preparation process of the broadband heterogeneous substrate piezoelectric composite material will be described in detail below.

本发明首先对一整块压电晶体(或压电陶瓷)进行切割，首先沿着X方向进行切割，选择切割参数如下：刀口宽度为l，步进为m+l，第一刀切割厚度为h，由于以晶柱高度按线性分布为例进行说明，所以一个周期内每两刀之间的厚度差固定为一个常数d，则第二刀切割厚度应为h+d，以此类推，第n刀切割厚度应为h+(n-l)d，其中，h+(n-l)d＜t，这样不能将样品切透，否则会影响样品中晶柱间的精确定位。X方向切割以n刀为一个周期，直到将整个压电晶体切完。然后将样品旋转90度，以同样切割程序在Y方向切割，这样就形成了压电晶柱阵列周期性排列于压电基底之上的结构。切割过程选用精密切割机，所有尺寸误差均在0.01mm范围内。The present invention first cuts a whole piece of piezoelectric crystal (or piezoelectric ceramics), and first cuts along the X direction, and selects the cutting parameters as follows: the width of the knife edge is l, the step is m+l, and the thickness of the first knife is h , because the height of the crystal column is linearly distributed as an example, so the thickness difference between every two cuts in a period is fixed as a constant d, then the thickness of the second cut should be h+d, and so on, the nth The cutting thickness of the knife should be h+(n-l)d, where h+(n-l)d<t, so that the sample cannot be cut through, otherwise it will affect the precise positioning of the crystal columns in the sample. Cutting in the X direction takes n knives as a cycle until the entire piezoelectric crystal is cut. Then the sample was rotated 90 degrees, and cut in the Y direction with the same cutting procedure, thus forming a structure in which piezoelectric crystal column arrays are periodically arranged on the piezoelectric substrate. The cutting process uses a precision cutting machine, and all dimensional errors are within 0.01mm.

在一个周期内的压电晶柱的高度各不相同，且每个压电晶柱平行于Z轴的四个侧面分别由四个不同深度的刀槽形成。即假设这个单元位于压电复合材料某一个周期的第x行和第y列，那么就可以分别计算出这个单元的四个侧面刀槽所应具有的深度分别为h+(x-l)d、h+(y-l)d、h+xd和h+yd，如图2所示。从而实现了每个压电晶柱均由不同深度的刀槽切割而成，那么在一个周期内就会形成n²/2种单元。由于晶柱的边界条件可以对晶柱的谐振频率产生一定的影响，从而经过上述切割工艺制备出的晶柱就会形成n²/2种谐振频率，而由于参差调谐效应，这些谐振频率叠加在一起就形成了宽带的特点。The heights of the piezoelectric crystal pillars in one period are different, and the four sides of each piezoelectric crystal pillar parallel to the Z axis are respectively formed by four sipe grooves with different depths. That is, assuming that this unit is located in the xth row and yth column of a certain cycle of the piezoelectric composite material, then the depths of the four side sipes of the unit can be calculated as h+(xl)d, h+( yl)d, h+xd and h+yd, as shown in Figure 2. Therefore, it is realized that each piezoelectric crystal column is cut by slits of different depths, and n² /2 types of units are formed in one cycle. Since the boundary conditions of the crystal column can have a certain influence on the resonance frequency of the crystal column, the crystal column prepared by the above cutting process will form n² /2 kinds of resonance frequencies, and due to the staggered tuning effect, these resonance frequencies are superimposed on the Together, they form the characteristics of broadband.

本发明以晶柱的高度按线性分布为例，选择压电陶瓷PZT5为压电晶体，聚合物选用聚氨酯，厚度t＝5mm，晶柱宽度m＝1mm，刀槽宽度l＝0.4mm，第一刀切割厚度h＝2mm，高度差d＝0.5mm，一个周期内晶柱数n＝7。测量出的试验结果Q值为4.89，如图4所示。In the present invention, the height of the crystal column is distributed as an example, the piezoelectric ceramic PZT5 is selected as the piezoelectric crystal, the polymer is polyurethane, the thickness t=5mm, the crystal column width m=1mm, the knife groove width l=0.4mm, the first knife cut Cutting thickness h=2mm, height difference d=0.5mm, number of crystal pillars in one cycle n=7. The measured test result Q value is 4.89, as shown in Figure 4.

本发明的压电复合材料的基底厚度取值范围为0.5～10mm。The base thickness of the piezoelectric composite material of the present invention ranges from 0.5mm to 10mm.

聚合物通常选择环氧树脂、聚氨酯、硅橡胶等粘接剂，这类粘接剂具有较好的流动性，可以灌注于经过以上切割形成的压电晶柱之间0.2～2mm宽的缝隙里。根据需要还可以选择直径小于0.1mm的金属粉末或小颗粒、真空玻璃微球等作为填充物，以改进聚合物的性能，进而改进复合压电材料的性能。The polymer usually chooses epoxy resin, polyurethane, silicone rubber and other adhesives. This type of adhesive has good fluidity and can be poured into the 0.2-2mm wide gap between the piezoelectric crystal columns formed by the above cutting. . Metal powder or small particles with a diameter of less than 0.1 mm, vacuum glass microspheres, etc. can also be selected as fillers as required to improve the performance of the polymer, and then improve the performance of the composite piezoelectric material.

聚合物灌注、固化后，要进行打磨整形，将样品制备成所需的圆形、方形或者任意形状。由于压电基底并未由于切割、灌注、打磨等工艺而破坏原有电极，所以只需要在另一个面通过物理或者化学沉积的方法在上表面制备一层易于焊接的金属薄膜作为上电极。After the polymer is poured and solidified, it needs to be polished and shaped to prepare the sample into the required round, square or arbitrary shape. Since the piezoelectric substrate does not damage the original electrode due to cutting, pouring, grinding and other processes, it is only necessary to prepare a layer of easy-to-weld metal film on the upper surface as the upper electrode by physical or chemical deposition on the other side.

以上通过详细实施例描述了本发明所提供的用于宽带换能器的压电复合材料，本领域的技术人员应当理解，在不脱离本发明实质的范围内，可以对本发明做一定的变形或修改；其制备方法也不限于实施例中所公开的内容。The piezoelectric composite materials for broadband transducers provided by the present invention have been described above through detailed examples. Those skilled in the art should understand that certain deformations or modifications can be made to the present invention within the scope not departing from the essence of the present invention. Modification; its preparation method is also not limited to the content disclosed in the examples.

Claims

1. the piezo-electricity composite material of a wide-band transducer, comprise piezoelectric crystal and polymer, piezoelectric crystal is divided into upper and lower two parts, and wherein, superstructure is evenly distributed a plurality of piezoelectricity crystal columns, substructure is a piezoelectric substrate, the height of described piezoelectricity crystal column is periodic difference, makes piezoelectric substrate in uneven thickness, and polymer is filled between the described piezoelectricity crystal column, the polarised direction of described piezoelectricity crystal column and piezoelectric substrate is characterized in that along the thickness direction of piezo-electricity composite material:

The area perpendicular to four sides of horizontal plane of each piezoelectricity crystal column has nothing in common with each other.

2. material as claimed in claim 1 is characterized in that, the difference in height of piezoelectricity crystal column is linear distribution or Gaussian Profile rule.

3. material as claimed in claim 1 is characterized in that, the length of side length of each piezoelectricity crystal column cross section is between 0.3～5mm.

4. material as claimed in claim 1 is characterized in that, the altitude range of each piezoelectricity crystal column is 0.5～15mm.

5. material as claimed in claim 1 or 2 is characterized in that, in each cycle, the height difference of piezoelectricity crystal column is between 0.1～5mm.

6. material as claimed in claim 1 is characterized in that, polymer is selected from a kind of in epoxy resin, polyurethane or the silicon rubber.

7. as claim 1 or 6 described materials, it is characterized in that, in polymer, fill metal dust, small metal particles or vacuum glass microballoon.

8. material as claimed in claim 7 is characterized in that, described metal dust, small metal particles or vacuum glass diameter of micro ball are less than 0.1mm.

9. material as claimed in claim 1 is characterized in that, described piezoelectric crystal is piezoelectric monocrystal or piezoelectric ceramic.