Double-spiral piezoelectric composite material structure

Abstract

The utility model relates to a double-helix type piezoelectric composite material structure, which comprises an upper electrode, a lower electrode, a polymer phase and a piezoelectric ceramic phase, and particularly, the piezoelectric ceramic phase is of a double-helix structure, and the piezoelectric ceramic phase and the polymer phase are alternately distributed at intervals. According to the utility model, the conventional piezoelectric ceramic phase arrangement mode is changed, and the piezoelectric ceramic phase is designed into a double-helix structure, so that the sound field directivity of the transducer is effectively improved, and meanwhile, under the limitation of the width, the electromechanical coupling coefficient, piezoelectric property and the like of a composite material as well as the sensitivity, bandwidth and the like of the transducer can be improved; the formed 2-2 and 1-3 type piezoelectric composite material structures effectively suppress crosstalk of transverse vibration, reduce energy loss generated by transverse coupling motion, enable a thickness vibration mode to be purer, and meet performance requirements of sensor elements with different functions.

Description

Technical Field

[0001] The utility model belongs to the technical field of electrical components, and in particular relates to a double-helix piezoelectric composite material structure. Background Art

[0002] With the development of material science, ultrasonic transducers are increasingly used in various fields, and piezoelectric materials are considered to be the "heart" of piezoelectric ultrasonic transducers. As core materials, they play a decisive role in the various properties of transducers. At present, the common piezoelectric layer materials of ultrasonic transducers are mostly perovskite ferroelectric crystals. Lead zirconate titanate (PZT) piezoelectric ceramics are mostly used in industrial production. In addition, there are a variety of high-performance piezoelectric single crystal materials, such as PMN-PT, PIN-PMN-PT, etc. These piezoelectric single crystals all show extremely high piezoelectric properties. However, as the vibration source of the transducer, there are problems such as fragility, weak resistance to mechanical impact, and high acoustic impedance. These problems also limit the bandwidth and sensitivity of ultrasonic transducers. Until the 1970s, a new type of composite material appeared. The material is composed of piezoelectric ceramics and high molecular polymers coupled and combined into one through a certain connection method. It is called a piezoelectric composite material. Common ones include 1-3 type and 2-2 type piezoelectric composite materials. While retaining certain performance advantages of piezoelectric single crystals, piezoelectric composites also have the advantages of high electromechanical coupling coefficient, low acoustic impedance, low dielectric constant, etc. due to their own structure. They can be prepared according to actual needs and are widely used in cutting-edge fields such as medical ultrasound imaging, bioengineering, and sensors. At the same time, piezoelectric composites have better performance advantages than single-component piezoelectric ceramic materials and have many advantages, including higher electromechanical coupling coefficient, lower acoustic impedance, better flexibility, etc. Based on these structural characteristics and advantages of piezoelectric composites, they are often used in sensing systems such as medical ultrasound imaging, industrial non-destructive testing, hydrophones, flow speed meters, etc.

[0003] However, piezoelectric composite materials are prepared by combining piezoelectric ceramic materials with high molecular polymers. Their configurations can be divided into 0-3 type, 1-3 type, 2-2 type, etc. according to their connectivity. The first digit of the configuration represents the number of connected dimensions of the piezoelectric phase, and the second digit represents the number of connected dimensions of the polymer phase. Common ones include: 2-2 type and 1-3 type piezoelectric composite material structures. Conventional methods for preparing piezoelectric composite materials include cast lamination, cutting and filling, and rolling film. These methods have problems such as low precision, low efficiency, and difficulty in high frequency. It is also difficult to prepare some piezoelectric composite materials with complex structures, which limits the application scenarios of piezoelectric composite materials.

[0004] For example: Patent No. CN201310114009.0, patent name 1-3 type piezoelectric composite material and its preparation method; Patent No. 201210099390.3, patent name preparation method of spiral parallel high-performance piezoelectric composite material. Obviously, the former is just a conventional uniform arrangement structure, the piezoelectric ceramic columns are arranged periodically, and the preparation method of this structure is difficult to process piezoelectric composite materials with complex structures; at the same time, although the piezoelectric phase in the piezoelectric composite material of the latter is a spiral structure, the overall structure size is large, the precision is low, and the preparation process is cumbersome, and it cannot be customized according to high quality according to demand, and cannot meet the performance requirements of the piezoelectric layer material in the high-frequency ultrasonic transducer. Therefore, the existing structure and In the preparation method, the conventional 2-2 and 1-3 piezoelectric composite materials are limited by traditional theories during design and preparation. The assembled transducer cannot meet the directivity requirements and is more used in low-frequency ultrasonic systems. It is difficult to adapt to medical high-frequency ultrasonic imaging systems. Moreover, the piezoelectric composite materials processed by the traditional preparation method are large in size and low in precision, which further limits the miniaturization and high frequency of ultrasonic transducers, and thus limits the application scenarios of piezoelectric composite materials. In addition, the above-mentioned piezoelectric composite materials cannot effectively suppress the crosstalk of lateral vibration, resulting in energy loss caused by lateral coupling motion, low electromechanical coupling coefficient, small bandwidth, low sensitivity of the transducer, and more complex thickness vibration mode. Summary of the invention

[0005] The technical problem to be solved by the utility model is to overcome the deficiencies of the prior art and provide an improved double-helix piezoelectric composite material structure.

[0006] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0007] A double-helix piezoelectric composite material structure comprises an upper electrode, a lower electrode, a polymer phase and a piezoelectric ceramic phase. In particular, the piezoelectric ceramic phase is in a double-helix structure, and the piezoelectric ceramic phase and the polymer phase are alternately distributed, wherein the width formed by the piezoelectric ceramic phase is l, and the width of the polymer phase portion alternately distributed with the piezoelectric ceramic phase is w, wherein l>w.

[0008] Preferably, the upper and lower surfaces of the overall material composed of the piezoelectric ceramic phase and the polymer phase are arranged flush. The advantage of the flush arrangement is that the piezoelectric composite material as the core of the transducer needs to have a smooth surface like a single-phase piezoelectric material to facilitate sputtering electrodes and coupling with the backing and matching layer.

[0009] According to a specific implementation and preferred aspect of the utility model, the piezoelectric ceramic phase accounts for 30%-80% of the total volume of the piezoelectric ceramic phase and the polymer phase. The volume ratio of the piezoelectric phase to the polymer phase affects the electromechanical coupling coefficient of the composite material, the piezoelectric performance and other key parameters, and can be adjusted to obtain a piezoelectric composite material with suitable performance when designing a suitable configuration according to different actual needs.

[0010] In a specific embodiment, the width of the piezoelectric ceramic phase is kept equal and in a spiral shape, and at the same time, the width of the polymer phase portion alternately distributed with the piezoelectric ceramic phase is kept equal and in a spiral shape, so as to facilitate cutting processing.

[0011] Furthermore, the inner ends of the double helix formed by the piezoelectric ceramic phase are connected or disconnected. Generally, when the piezoelectric phase is disconnected and the piezoelectric phase is separated, the lateral disturbance during vibration can be reduced to a certain extent (of course, the inner ends of the double helix are connected, which is more convenient for processing and forming, and each has its own advantages).

[0012] According to another specific implementation and preferred aspect of the present invention, the polymer phase and the piezoelectric ceramic phase are connected in two dimensions to form a 2-2 type double helical piezoelectric composite material structure.

[0013] Preferably, the piezoelectric ceramic phase accounts for 40%-80% of the total volume of the piezoelectric ceramic phase and the polymer phase. Generally, the piezoelectric ceramic phase accounts for 50%-60% of the total volume of the piezoelectric ceramic phase and the polymer phase. The appropriate piezoelectric volume fraction can improve the electromechanical coupling coefficient, piezoelectric performance, etc. of the composite material, as well as the sensitivity and bandwidth of the transducer.

[0014] - According to another specific implementation and preferred aspect of the present invention, the polymer phase is connected in three dimensions, and the piezoelectric ceramic phase is connected in one dimension to form a 1-3 type double helical piezoelectric composite material structure.

[0015] Preferably, the piezoelectric ceramic phase accounts for 30%-70% of the total volume of the piezoelectric ceramic phase and the polymer phase. Generally, the piezoelectric ceramic phase accounts for 30%-60% of the total volume of the piezoelectric ceramic phase and the polymer phase, which is obviously less than the 2-2 type double helical piezoelectric composite structure. Therefore, compared with the 2-2 type piezoelectric composite material, it has better flexibility and a purer thickness vibration mode.

[0016] In addition, the piezoelectric ceramic phase includes a plurality of spiral interval segments spaced apart along the spiral track, and the polymer phase also includes a filling segment filling between two adjacent spiral interval segments in the spiral distribution path.

[0017] In short, the above-mentioned double-helix piezoelectric composite material structure can be an improved 1-3 type double-helix structure piezoelectric composite material based on the 2-2 type, which effectively suppresses the crosstalk of lateral vibration, reduces the energy loss caused by lateral coupling movement, improves the sensitivity of the transducer, makes the thickness vibration mode more pure, further improves the electromechanical coupling coefficient, and increases the bandwidth accordingly. At the same time, it has good performance and can obtain products of various shapes as needed to meet the performance requirements of sensor elements with different functions.

[0018] Due to the implementation of the above technical solution, the utility model has the following advantages compared with the prior art:

[0019] The existing piezoelectric composite material structure, the conventional 2-2 and 1-3 piezoelectric composite materials are limited by the traditional theory in design and preparation, and the assembled transducer cannot meet the directivity requirements. They are more used in low-frequency ultrasonic systems and are difficult to adapt to medical high-frequency ultrasonic imaging systems. Moreover, the piezoelectric composite materials processed by the traditional preparation method are large in size and low in precision, which further limits the miniaturization and high frequency of the ultrasonic transducer, and thus limits the application scenarios of the piezoelectric composite materials. In addition, the above-mentioned piezoelectric composite materials cannot effectively suppress the crosstalk of lateral vibration, resulting in energy loss caused by lateral coupling motion, low electromechanical coupling coefficient, small bandwidth, low sensitivity of the transducer, more complex thickness vibration mode and other deficiencies. The utility model cleverly solves the various deficiencies of the existing structure by overall design of the structure of the double-helix piezoelectric composite material. The piezoelectric composite material is adopted, the piezoelectric ceramic phase is in a double helix structure, and the piezoelectric ceramic phase and the polymer phase are alternately distributed, and then the upper electrode and the lower electrode are respectively formed on the upper and lower surfaces to form a 2-2 type piezoelectric composite material in the form of a double helix structure. Therefore, the utility model changes the conventional arrangement of the piezoelectric ceramic phases, and designs the piezoelectric ceramic phases into a double helix structure, so that the directivity of the transducer sound field is effectively improved. At the same time, under the width restriction, the electromechanical coupling coefficient of the composite material, the piezoelectric performance, etc., as well as the sensitivity and bandwidth of the transducer can be improved. In addition, the formed 2-2 and 1-3 type piezoelectric composite material structures effectively suppress the crosstalk of lateral vibration, reduce the energy loss caused by lateral coupling movement, make the thickness vibration mode purer, and meet the performance requirements of sensor elements with different functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0021] Figure 1 Schematic diagram of the structure of the 2-2 type double helix structure piezoelectric composite material in Example 1 (connected type);

[0022] Figure 2 for Figure 1 A schematic diagram of the main view;

[0023] Figure 3 Schematic diagram of the structure of the 2-2 type double helix structure piezoelectric composite material in Example 1 (partition type);

[0024] Figure 4 for Figure 3 A schematic diagram of the main view;

[0025] Figure 5 This is a schematic diagram of the structure of the 1-3 type double helix structure piezoelectric composite material in Example 2;

[0026] Figure 6 for Figure 5 A schematic diagram of the main view;

[0027] Wherein: 1. upper electrode; 2. lower electrode; 3. polymer phase; 30. filling segment; 4. piezoelectric ceramic phase; 40. spiral spacer segment. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0029] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0030] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0031] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0032] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0033] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0034] Example 1

[0035] like Figure 1 and Figure 2 As shown, the double-helix piezoelectric composite material structure of this embodiment includes an upper electrode 1, a lower electrode 2, a polymer phase 3, and a piezoelectric ceramic phase 4, wherein the piezoelectric ceramic phase 4 is a double-helix structure, and the piezoelectric ceramic phase 4 and the polymer phase 3 are alternately distributed.

[0036] In some specific embodiments, the width of the piezoelectric ceramic phase is l, and the width of the polymer phase portion alternately distributed with the piezoelectric ceramic phase is w, wherein l>w. Generally, l is at least 1.5 to 2.5 times of w.

[0037] The upper and lower surfaces of the overall material formed by the piezoelectric ceramic phase 4 and the polymer phase 3 are arranged flush. The piezoelectric ceramic phase accounts for 40%-80% of the total volume of the piezoelectric ceramic phase and the polymer phase. At the same time, the width of the piezoelectric ceramic phase remains equal in a spiral shape, and at the same time, the width of the polymer phase portion alternately distributed with the piezoelectric ceramic phase remains equal in a spiral shape. It is convenient for cutting and processing.

[0038] In addition, the polymer phase 3 and the piezoelectric ceramic phase 4 are connected in two dimensions to form a 2-2 type double helix piezoelectric composite material structure, and the inner ends of the double helix formed by the piezoelectric ceramic phase 4 are connected. The connection here is mainly to facilitate laser cutting and forming.

[0039] Combination Figure 3 and Figure 4 As shown, its structure is exactly the same as the above, except that the inner end of the double helix formed by the piezoelectric ceramic phase 4 is disconnected. The disconnection here (compared to the connection here) can better suppress the crosstalk of the lateral vibration, reduce the energy loss caused by the lateral coupling movement, and make the thickness vibration mode purer.

[0040] Specifically, the 2-2 type double helical piezoelectric composite material structure expands outward with a base circle of radius r as the center, the piezoelectric ceramic phase 4 and the polymer phase 3 are alternately distributed, and the widths of the piezoelectric ceramic phase 4 and the polymer phase 6 are l and w respectively, the pitch is k, the number of spiral coils is N, and the double helical structure piezoelectric composite material is designed as needed by adjusting parameters, and its equation is:

[0041]

[0042] The calculation formula for the volume fraction of the piezoelectric phase of the piezoelectric composite material is:

[0043]

[0044] In the above formula, k vf represents the volume fraction of the piezoelectric phase of the piezoelectric composite material, d is the base circle diameter, D is the outer diameter of the helix, t is the thickness of the piezoelectric composite material, i represents the helix parameter, and ξ is the correction coefficient.

[0045] Example 2

[0046] like Figure 5 and Figure 6 As shown, the double-helix piezoelectric composite material structure of this embodiment includes an upper electrode 1, a lower electrode 2, a polymer phase 3, and a piezoelectric ceramic phase 4, wherein the piezoelectric ceramic phase 4 is a double-helix structure, and the piezoelectric ceramic phase 4 and the polymer phase 3 are alternately distributed.

[0047] At the same time, compared with Example 1, the difference between this embodiment is that the polymer phase 3 is connected in the three-dimensional direction, and the piezoelectric ceramic phase 4 is connected in the one-dimensional direction to form a 1-3 type double-helix piezoelectric composite material structure, in which the piezoelectric ceramic phase 4 accounts for 30%-70% of the total volume of the piezoelectric ceramic phase 4 and the polymer phase 3.

[0048] In addition, the piezoelectric ceramic phase 4 includes a plurality of spiral spacing segments 40 spaced apart along the spiral track, and the polymer phase 3 also includes a filling segment 30 filling between two adjacent spiral spacing segments 40 in the spiral distribution path.

[0049] In short, the above-mentioned double-helix piezoelectric composite material structure can be an improved 1-3 type double-helix structure piezoelectric composite material based on the 2-2 type, which effectively suppresses the crosstalk of lateral vibration, reduces the energy loss caused by lateral coupling movement, improves the sensitivity of the transducer, makes the thickness vibration mode more pure, further improves the electromechanical coupling coefficient, and increases the bandwidth accordingly. At the same time, it has good performance and can obtain products of various shapes as needed to meet the performance requirements of sensor elements with different functions.

[0050] In summary, the piezoelectric composite material is adopted, the piezoelectric ceramic phase is in a double helix structure, and the piezoelectric ceramic phase and the polymer phase are alternately distributed, and then the upper electrode and the lower electrode are respectively formed on the upper and lower surfaces to form a 1-3 or 2-2 type piezoelectric composite material in the form of a double helix structure. Therefore, on the one hand, the utility model changes the conventional arrangement of the piezoelectric ceramic phases, and designs the piezoelectric ceramic phases into a double helix structure, so that the directivity of the transducer sound field is effectively improved; on the other hand, under the width restriction of the composite material, the electromechanical coupling coefficient, piezoelectric performance, etc. of the composite material as well as the sensitivity and bandwidth of the transducer can be improved. In addition, the formed 2-2 and 1-3 type piezoelectric composite material structures effectively suppress the crosstalk of lateral vibration, reduce the energy loss caused by lateral coupling motion, make the thickness vibration mode purer, and meet the performance requirements of sensor elements with different functions (1-3 type double helix structure piezoelectric composite material performance The piezoelectric composite material can be better than the 2-2 type double helix structure piezoelectric composite material, and the thickness vibration mode is purer); the third aspect is that the piezoelectric composite material as the core of the transducer needs to have a smooth surface like the single-phase piezoelectric material to facilitate the sputtering of electrodes and coupling with the backing and matching layer; the fourth aspect is that the volume fraction of the piezoelectric phase in the piezoelectric composite material is related to the configuration, size and arrangement, which is expressed as the volume ratio of the piezoelectric phase to the polymer phase, which affects the electromechanical coupling coefficient Kt of the composite material, piezoelectric performance and other key parameters. When designing a suitable configuration according to different actual needs, the piezoelectric composite material with adapted performance can be obtained by adjusting the volume fraction; the fifth aspect is that the inner end of the double helix formed by the piezoelectric ceramic phase is disconnected, and the piezoelectric phase is in a separated state when disconnected, which can optimally reduce the lateral disturbance during vibration to a certain extent; the sixth aspect is that this structure can be prepared by laser cutting, etching, 3D printing and other processes, which is easy to implement.

[0051] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A double-helix piezoelectric composite material structure, comprising an upper electrode (1), a lower electrode (2), a polymer phase (3), and a piezoelectric ceramic phase (4), Features: The piezoelectric ceramic phase (4) has a double helix structure, and the piezoelectric ceramic phase (4) and the polymer phase (3) are distributed alternately, wherein the width formed by the piezoelectric ceramic phase (4) is l, and the width of the polymer phase (3) portion that is distributed alternately with the piezoelectric ceramic phase (4) is w, wherein l>w.

2. The double-helix piezoelectric composite material structure according to claim 1, Features: The upper and lower surfaces of the overall material formed by the piezoelectric ceramic phase (4) and the polymer phase (3) are arranged flush.

3. The double-helix piezoelectric composite material structure according to claim 1, Features: The piezoelectric ceramic phase (4) accounts for 30% to 80% of the total volume of the piezoelectric ceramic phase (4) and the polymer phase (3).

4. The double-helix piezoelectric composite material structure according to claim 1, Features: The width of the piezoelectric ceramic phase (4) remains equal and is in a spiral shape; the width of the polymer phase (3) portion that is distributed alternately with the piezoelectric ceramic phase (4) remains equal and is in a spiral shape.

5. The double-helix piezoelectric composite material structure according to claim 1, Features: The inner ends of the double helix formed by the piezoelectric ceramic phase (4) are connected or disconnected.

6. The double-helix piezoelectric composite structure according to any one of claims 1 to 5, Features: The polymer phase (3) and the piezoelectric ceramic phase (4) are both connected in two-dimensional directions to form a 2-2 type double helical piezoelectric composite material structure.

7. The double-helix piezoelectric composite material structure according to claim 6, Features: The piezoelectric ceramic phase (4) accounts for 40% to 80% of the total volume of the piezoelectric ceramic phase (4) and the polymer phase (3).

8. The double-helix piezoelectric composite structure according to any one of claims 1 to 5, Features: The polymer phase (3) is connected in a three-dimensional direction, and the piezoelectric ceramic phase (4) is connected in a one-dimensional direction, so as to form a 1-3 type double helical piezoelectric composite material structure.

9. The double-helix piezoelectric composite material structure according to claim 8, Features: The piezoelectric ceramic phase (4) accounts for 30% to 70% of the total volume of the piezoelectric ceramic phase (4) and the polymer phase (3).

10. The double-helix piezoelectric composite material structure according to claim 9, Features: The piezoelectric ceramic phase (4) includes a plurality of spiral interval segments (40) spaced apart along a spiral track, and the polymer phase (3) further includes a filling segment (30) filling between two adjacent spiral interval segments (40) in the spiral distribution path.

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