Piezoelectric material preparation method and piezoelectric material

Abstract

The present invention relates to a method for preparing a piezoelectric material and a piezoelectric material. At least one piezoelectric ceramic column is positioned in a mold by a positioning assembly. A pouring cavity is defined between the positioning assembly and the mold to accommodate at least part of the piezoelectric ceramic column. A matrix material is poured into the pouring cavity through a pouring process to wrap the piezoelectric ceramic column located in the pouring cavity. The matrix material is solidified through a curing process to form a piezoelectric element. The piezoelectric element includes the solidified matrix material and the piezoelectric ceramic column wrapped in the matrix material. The piezoelectric element is cut to a preset thickness to obtain the piezoelectric material. The present application positions the piezoelectric ceramic column in the pouring cavity of the mold by a positioning assembly, and then pours the matrix material into the piezoelectric ceramic column to wrap the piezoelectric ceramic column. Thus, a piezoelectric material in which the piezoelectric ceramic column is arranged in the matrix material as required can be prepared through a simple preparation process.

Description

Technical Field

[0001] The present invention relates to the technical field of piezoelectric materials, and in particular to a piezoelectric material preparation method and the piezoelectric material. Background Art

[0002] Type 1-3 piezoelectric composites are composed of one-dimensionally interconnected piezoelectric ceramic pillars arranged in parallel within a three-dimensionally interconnected polymer matrix, with the pillars perpendicular to the electrode surfaces. The superior performance of these composites is closely related to their preparation process, which is currently complex, and the placement of the pillars within the polymer matrix is difficult to achieve. Summary of the Invention

[0003] Based on this, it is necessary to provide a piezoelectric material preparation method and piezoelectric material, so as to simplify the preparation process and facilitate the arrangement of piezoelectric ceramic columns in the piezoelectric material as required.

[0004] In one aspect of the present application, a method for preparing a piezoelectric material is provided, comprising:

[0005] Positioning at least one piezoelectric ceramic column in the mold by a positioning assembly; defining a pouring cavity between the positioning assembly and the mold to accommodate at least part of the piezoelectric ceramic column;

[0006] pouring a matrix material into the pouring cavity through a pouring process to wrap the piezoelectric ceramic column located in the pouring cavity;

[0007] The matrix material is solidified through a solidification process to form a piezoelectric element; the piezoelectric element includes the solidified matrix material and a piezoelectric ceramic column wrapped in the matrix material;

[0008] The piezoelectric element is cut into a predetermined thickness to obtain the piezoelectric material.

[0009] In one embodiment, the positioning assembly includes a first positioning member and a second positioning member;

[0010] Positioning at least one piezoelectric ceramic column in a predetermined manner in the mold by a positioning component specifically includes:

[0011] Fixing the two ends of the piezoelectric ceramic column along its axial direction to the first positioning member and the second positioning member according to preset positions respectively;

[0012] The positioning assembly with the piezoelectric ceramic column positioned thereon is assembled into the mold.

[0013] In one embodiment, the mold has a receiving cavity with an open end, and the receiving cavity has a bottom wall opposite to the opening;

[0014] Assembling the positioning assembly with the piezoelectric ceramic column in the mold specifically includes:

[0015] One of the first positioning member and the second positioning member is placed on the bottom wall, so that the other of the first positioning member and the second positioning member blocks the opening to form a perfusion cavity.

[0016] In one embodiment, the other of the first positioning member and the second positioning member is provided with a through hole capable of communicating with the perfusion cavity;

[0017] Pouring the matrix material into the perfusion cavity through the perfusion process to encapsulate the piezoelectric ceramic column located in the perfusion cavity specifically includes:

[0018] On the other side of the first positioning member and the second positioning member facing away from one of the other, matrix material is poured into the pouring cavity through the through hole by a pouring process to wrap the piezoelectric ceramic column located in the pouring cavity.

[0019] In one embodiment, a plurality of piezoelectric ceramic pillars are provided;

[0020] The plurality of piezoelectric ceramic columns are regularly arranged relative to the positioning component; or the plurality of piezoelectric ceramic columns are irregularly arranged relative to the positioning component.

[0021] In one embodiment, the orthographic projection of the piezoelectric ceramic column on a plane perpendicular to the axial direction of the piezoelectric ceramic column is a first projection; the shape of the first projection includes a circle, a square or a polygon; and / or the orthographic projection of the matrix material on a plane perpendicular to the axial direction of the piezoelectric ceramic column is a second projection; the shape of the second projection includes a circle, a square or a polygon.

[0022] In one embodiment, the preset thickness range is 0.1 mm-10 mm.

[0023] In one embodiment, the positioning component is made of the same material as the base material.

[0024] In another aspect of the present application, a piezoelectric material is provided, which is prepared using the above-mentioned piezoelectric material preparation method.

[0025] In one embodiment, the thickness of the piezoelectric material has an electromechanical coupling coefficient in the range of 0.5-0.72.

[0026] The above-mentioned piezoelectric material preparation method, piezoelectric material and piezoelectric material preparation device use a positioning component to position the piezoelectric ceramic column in the infusion cavity of the mold, and then infuse the matrix material into the piezoelectric ceramic column to wrap it. In this way, a piezoelectric material in which the piezoelectric ceramic column is arranged in the matrix material according to needs can be prepared through a simple preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A flow chart of a method for preparing a piezoelectric material according to an embodiment of the present invention;

[0028] Figure 2 A schematic structural diagram of a process for preparing a piezoelectric material according to an embodiment of the present invention;

[0029] Figure 3 Schematic diagram of the structure of a piezoelectric element according to an embodiment of the present invention;

[0030] Figure 4 Schematic diagram of the structure of a piezoelectric material according to an embodiment of the present invention;

[0031] Figure 5 This is a flowchart of step S110 according to an embodiment of the present invention;

[0032] Figure 6 is a schematic diagram of a first projection and a second projection according to an embodiment of the present invention;

[0033] Figure 7 A flow chart of a method for preparing a piezoelectric material according to another embodiment of the present invention;

[0034] Figure 8 FIG. 4 is a flow chart of a method for preparing a piezoelectric material according to another embodiment of the present invention.

[0035] Description of reference numerals:

[0036] 10. Positioning assembly; 11. First positioning member; 11a. Through hole; 12. Second positioning member; 13. Infusion cavity; 20. Mold; 21. Opening; 22. Accommodating cavity; A. Piezoelectric element; 100. Piezoelectric ceramic column; 101. First projection; 200. Base material; 201. Second projection; B. Piezoelectric material. DETAILED DESCRIPTION

[0037] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0038] In the description of the present invention, 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 to 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 invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0040] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0041] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0042] 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 an intermediate 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 an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0043] In addition, the drawings are not drawn to a 1:1 scale, and the relative sizes of the elements in the drawings are drawn only as examples and not necessarily according to the true scale.

[0044] For ease of description, the drawings only show structures related to the embodiments of the present invention.

[0045] In order to facilitate understanding of the technical solution of the present invention, prior to detailed description, the existing piezoelectric materials are first described.

[0046] As mentioned in the background, Type 1-3 piezoelectric composites consist of piezoelectric ceramics fabricated into columns or fibers, arranged in a regular pattern within a three-dimensionally interconnected polymer phase. However, current piezoelectric material preparation methods often require either a regular or random arrangement of the piezoelectric ceramic columns. This often requires complex fabrication techniques to achieve the desired arrangement of the piezoelectric ceramics within the polymer phase.

[0047] Therefore, it is necessary to provide a piezoelectric material preparation method and a piezoelectric material with a simple preparation process and which enables piezoelectric ceramics to be arranged in a polymer matrix as required.

[0048] Figure 1 A flow chart showing a method for preparing a piezoelectric material B in one embodiment of the present invention is shown; Figure 2 A schematic structural diagram of a process for preparing a piezoelectric material B in one embodiment of the present invention is shown; Figure 3 FIG2 shows a schematic structural diagram of a piezoelectric element A in an embodiment of the present invention; Figure 4 FIG. 4 shows a schematic structural diagram of a piezoelectric material B in an embodiment of the present invention.

[0049] In conjunction with some of the following embodiments, it can be understood that the desired piezoelectric material B is obtained by processing the piezoelectric element A. The provided piezoelectric material B includes product forms such as an intermediate state (i.e., a semi-finished product) or a final state (i.e., a finished product), and the piezoelectric element A includes product forms such as an intermediate state (i.e., a semi-finished product) or a final state (i.e., a finished product). The piezoelectric element A is an intermediate state of the piezoelectric material B. In other words, the piezoelectric material B comes from at least a portion of the piezoelectric element A. Since the focus of the embodiments of the present application is on the methods involved in some of the following embodiments, the relevant specific structures and related processes for forming the intermediate state or the final state are not described here.

[0050] Please refer to Figure 1 、 Figure 2 、 Figure 3 and Figure 4 One embodiment of the present invention provides a method for preparing a piezoelectric material B, comprising:

[0051] S110, positioning at least one piezoelectric ceramic column 100 in the mold 20 by the positioning assembly 10; defining a pouring cavity 13 for accommodating at least part of the piezoelectric ceramic column 100 between the positioning assembly 10 and the mold 20;

[0052] S120, pouring the matrix material 200 into the pouring cavity 13 through a pouring process to wrap the piezoelectric ceramic column 100 located in the pouring cavity 13;

[0053] S130, curing the base material 200 through a curing process to form a piezoelectric element A; the piezoelectric element A includes the cured base material 200 and the piezoelectric ceramic column 100 wrapped in the base material 200;

[0054] S140 , cutting the piezoelectric element A into a preset thickness to obtain a piezoelectric material B.

[0055] In step S110, the positioning component 10 can be a component for positioning the piezoelectric ceramic column 100 along the axial direction, such as providing a limiting groove adapted to the piezoelectric ceramic column 100 on two surfaces of the mold 20 perpendicular to the axial direction, or a component for positioning the piezoelectric ceramic column 100 along the radial direction, such as a component for clamping the piezoelectric ceramic column 100 along the radial direction, etc. As long as the piezoelectric ceramic column 100 can be positioned in the mold 20, no limitation is made here. The mold 20 can be prepared as required, and the size, outer shape, etc. of the mold 20 can be adaptively adjusted as required, as long as the mold 20 can cooperate with the positioning component 10 to position the piezoelectric ceramic column 100. Among them, the surface of the positioning component 10 and the inner wall of the mold 20 enclose a perfusion cavity 13, which provides a perfusion space for the subsequent matrix material 200 through the perfusion cavity 13 while accommodating the piezoelectric ceramic column 100.

[0056] In step S120, the infusion process involves pouring liquid matrix material 200 into the infusion cavity 13. This process can be accomplished by opening a through hole in the positioning assembly 10 or the mold 20, or by other methods, without limitation. Enveloping the piezoelectric ceramic pillar 100 with matrix material 200 means that the matrix material 200 covers the circumferential surface of the piezoelectric ceramic pillar 100.

[0057] In step S130, the curing process solidifies the liquid matrix material 200 encapsulating the piezoelectric ceramic pillars 100. The solidified body formed by the curing process, which is composed of the solidified matrix material 200 and the piezoelectric ceramic pillars 100 encapsulated therein, is the piezoelectric element A.

[0058] In step S140, the preset thickness refers to the desired thickness of the piezoelectric material B. In the embodiments of the present application, the piezoelectric material B can be obtained by cutting the piezoelectric element A. However, other methods can also be used to obtain the piezoelectric material B of the desired size from the piezoelectric element A, and this is not limited to cutting. In other embodiments, a preset amount of liquid matrix material 200 can be poured, and the piezoelectric material B of the desired size can be directly formed after solidification.

[0059] In this way, the piezoelectric ceramic column 100 is positioned in the pouring cavity 13 of the mold 20 by the positioning component 10, ensuring the reliable positioning of the piezoelectric ceramic column 100 and preventing the piezoelectric ceramic column 100 from shifting or tilting during the preparation process. The matrix material 200 is then poured into the piezoelectric ceramic column 100 to wrap it, so that the piezoelectric ceramic column 100 can be prepared through a simple preparation process, and the piezoelectric material B arranged in the matrix material 200 as required can be prepared.

[0060] Please refer again Figure 2 In some embodiments, the piezoelectric ceramic column 100 can be a lead-based piezoelectric ceramic column or a lead-free piezoelectric ceramic column. Optionally, the lead-based piezoelectric ceramic column includes a lead zirconate titanate piezoelectric ceramic column, and the lead-free piezoelectric ceramic column includes a tungsten bronze structured ceramic column, a bismuth layered structured ceramic column, a perovskite structured ceramic column, etc., without limitation herein. In the embodiments of the present application, a lead zirconate titanate piezoelectric ceramic column can optionally be used.

[0061] It should be noted that piezoelectric ceramics refer to ferroelectric ceramic materials that exhibit the piezoelectric effect after being polarized with high-voltage direct current. When a polarized piezoelectric ceramic is deformed by mechanical force, bound charges of equal magnitude and opposite sign appear on two surfaces opposite the polarization direction, with the surface charge density proportional to the applied force. This polarization, generated solely by deformation in the absence of an external electric field, is known as the direct piezoelectric effect, a property known as piezoelectricity. Piezoelectric ceramics placed in an external electric field can undergo geometric deformation, converting electrical energy into mechanical energy. This phenomenon is known as the inverse piezoelectric effect.

[0062] By utilizing the piezoelectric effect or the inverse piezoelectric effect, or both the forward and inverse piezoelectric effects, piezoelectric ceramics have been widely used in electronic components such as high-voltage ignition devices, displacement sensors, accelerators, brakes, resonators, filters, underwater acoustic transducers, and piezoelectric transformers.

[0063] Figure 5 FIG. 1 is a flow chart showing step S110 in an embodiment of the present invention.

[0064] See Figure 5 In some embodiments, the positioning assembly 10 includes a first positioning member 11 and a second positioning member 12. Step S110 specifically includes:

[0065] S111, fixing the two ends of the piezoelectric ceramic column 100 along its axial direction to the first positioning member 11 and the second positioning member 12 according to preset positions respectively;

[0066] S112 , assembling the positioning assembly 10 with the piezoelectric ceramic column 100 positioned thereon into the mold 20 .

[0067] In this way, the first positioning member 11 and the second positioning member 12 can respectively position the two ends of the piezoelectric ceramic column 100, thereby preventing the piezoelectric ceramic column 100 from being squeezed by the matrix material 200 and tilting or shifting when the matrix material 200 is poured, resulting in an error between the positioning of the piezoelectric ceramic column 100 in the solidified piezoelectric element A and the preset method.

[0068] It is understood that the preset positions in this application refer to the three-dimensional coordinate arrangement of the piezoelectric ceramic pillars 100 in different application scenarios based on the desired spatial sound fields. Of course, in other embodiments, the arrangement of the piezoelectric ceramic pillars 100 can also be obtained according to other methods, which are not limited here.

[0069] Please combine Figure 2As shown, in some embodiments, the mold 20 has a receiving cavity 22 with an opening 21 at one end, and the receiving cavity 22 has a bottom wall opposite the opening 21. Step S112 specifically includes placing one of the first positioning member 11 and the second positioning member 12 on the bottom wall, so that the other of the first positioning member 11 and the second positioning member 12 blocks the opening 21 to form the infusion cavity 13. In this way, the mold 20 can more securely assemble the positioning assembly 10 with the piezoelectric ceramic column 100 positioned therein, preventing the positioning assembly 10 and the piezoelectric ceramic column 100 from falling out of the mold 20 during infusion.

[0070] Furthermore, the other of the first positioning member 11 and the second positioning member 12 is provided with a through hole capable of communicating with the perfusion cavity 13. Step S120 specifically includes, on a side of the other of the first positioning member 11 and the second positioning member 12 facing away from the other, pouring the matrix material 200 into the perfusion cavity 13 through the through hole through a perfusion process to encapsulate the piezoelectric ceramic column 100 located within the perfusion cavity 13. In this way, providing a through hole in the first positioning member 11 or the second positioning member 12 avoids the need for drilling in the mold 20, improving the versatility of the mold 20. When adapting to the preparation of different piezoelectric materials, only the first positioning member 11 or the second positioning member 12 needs to be replaced.

[0071] In the embodiments of the present application, to enhance the convenience of the infusion process, a second positioning member 12 is placed on the bottom wall, and a first positioning member 11 blocks the opening 21 to form the infusion cavity 13. A through hole 11a is provided on the first positioning member 11. This way, the through hole 11a can guide the matrix material 200 into the infusion cavity 13. Furthermore, the through hole 11a provided on the first positioning member 11 can avoid incomplete infusion that would otherwise occur if the through hole 11a were provided on the mold 20.

[0072] like Figure 2 As shown, in some embodiments, the base material 200 includes at least one of polymethyl methacrylate, epoxy resin, silicone rubber, polyethylene, polypropylene, polyvinylidene fluoride, and nylon. In addition, the base material 200 may also optionally include at least one of a dispersant, a diluent, and a curing agent, which are not limited herein.

[0073] Combine Figure 2 and Figure 3In some embodiments, the material of the first positioning member 11 is the same as the matrix material 200. This allows the first positioning member 11 and the piezoelectric ceramic pillar 100 encased therein to be formed into a portion of the piezoelectric element A without removal after the matrix material 200 is poured and solidified, thereby improving the utilization rate of the piezoelectric ceramic pillar 100. In other embodiments, the material of the second positioning member 12 is the same as the matrix material 200. This allows the second positioning member 12 and the piezoelectric ceramic pillar 100 encased therein to be formed into a portion of the piezoelectric element A without removal after the matrix material 200 is poured and solidified, thereby improving the utilization rate of the piezoelectric ceramic pillar 100. In yet other embodiments, the material of both the first positioning member 11 and the second positioning member 12 is the same as the matrix material 200, and their functions are not further described herein. Of course, in some embodiments, the material of the first positioning member 11 and the second positioning member 12 may not be the same as the matrix material 200, and this is not a limitation here.

[0074] Combine Figure 2 and Figure 4 As shown, in some embodiments, a plurality of piezoelectric ceramic columns 100 are provided. The plurality of piezoelectric ceramic columns 100 are regularly arranged relative to the positioning component 10. It should be noted that regular arrangement also refers to periodic arrangement. In other embodiments, the plurality of piezoelectric ceramic columns 100 are irregularly arranged relative to the positioning component 10. It should be noted that irregular arrangement also refers to non-periodic arrangement, which can be adaptively selected according to actual application scenarios and actual needs. It can be understood that the number of piezoelectric ceramic columns 100 can be any number from 1 to n. Specifically in the embodiments of the present application, after sound field simulation, combined with structural design, circuit design and imaging effects, Figure 2 or Figure 4 For example, the piezoelectric ceramic pillars 100 include 18 piezoelectric ceramic pillars 100 , and the 18 piezoelectric ceramic pillars 100 are randomly arranged relative to the positioning assembly 10 to obtain the best 3D ultrasonic imaging effect.

[0075] Figure 6 A schematic diagram of a first projection 101 and a second projection 201 is shown in one embodiment of the present invention.

[0076] See Figure 6 In some embodiments, the orthographic projection of the piezoelectric ceramic column 100 along the axial direction of the piezoelectric ceramic column 100 is a first projection 101, and the shape of the first projection 101 includes a circle (such as Figure 6 (a) and (d) in the figure), square (such as Figure 6 (b) and (c) in Figure ) or polygons.

[0077] In order to make the piezoelectric ceramic column 100 have a smaller electrostatic capacitance, thereby reducing the charging and discharging time, and further improving the receiving sensitivity of the piezoelectric ceramic column 100 used in electronic components (such as sensors), the diameter of the piezoelectric ceramic column 100 is as small as possible. However, some piezoelectric ceramic columns 100 in the related art are difficult to reduce their diameter to less than 5 mm due to insufficient material toughness. The inventors have found through research that since the solidified piezoelectric element A in this application, the piezoelectric ceramic column 100 is embedded in the matrix material 200, has higher strength and flexibility, so the diameter of the piezoelectric ceramic column 100 can be reduced.

[0078] As specific as Figure 6 Figure (a) or Figure 6 In the embodiment shown in Figure (d), the shape of the first projection 101 is circular. The diameter range of the first projection 101 is 0.1mm-1mm. It can be understood that, that is, the cross-sectional shape of the piezoelectric ceramic column 100 is circular, and its diameter is 0.1mm-1mm. It should be noted that, due to the limitation of processing capacity, the diameter of the piezoelectric ceramic column 100 should not be less than 0.1mm due to the easy breakage and bending during the molding process of the tiny piezoelectric ceramic column 100. At the same time, if the diameter of the piezoelectric ceramic column 100 is large, the matrix material 200 will have a poor suppression of its radial vibration. Therefore, the maximum limit of the diameter of the piezoelectric ceramic column 100 in this application may be less than 1mm.

[0079] In some other embodiments, the orthographic projection of the base material 200 along the axial direction of the piezoelectric ceramic column 100 is a second projection 201, and the shape of the second projection 201 includes a circle (eg Figure 6 (b) and (d) in the figure), square (such as Figure 6 (a) in Figure ) or polygons (such as Figure 6 (c) and (d) in FIG). It should be noted that the piezoelectric ceramic column 100 and the mold 20 in this application can be adaptively adjusted in their outer shapes according to actual needs, and the base material 200 solidified and formed in the mold 20 can also be solidified to form different outer shapes.

[0080] Please refer again Figure 2 In some embodiments, the preset thickness range is 0.1 mm to 10 mm. Due to processing limitations, it is difficult to reduce the thickness of the piezoelectric material B to less than 0.1 mm. As the thickness of the piezoelectric material B increases, the matrix material 200 exerts greater constraints on the piezoelectric ceramic pillars 100 encapsulated therein, resulting in greater vibration energy loss, which in turn affects the thickness electromechanical coupling coefficient of the piezoelectric material B. Therefore, the thickness should not exceed 10 mm.

[0081] It should be noted that the preset thickness is the thickness of the obtained piezoelectric material B. Set the preset thickness to t, that is, the thickness of the piezoelectric material B is set to t, set the frequency constant to N, set the resonant frequency to f, and the thickness formula of the piezoelectric material B is t=N / f. For example, the resonant frequency (f) required in this application is 2.5Mhz. It can be calculated that the thickness of the piezoelectric material B is 0.6mm. The diameter of the piezoelectric material B affects, for example, the bandwidth, sound pressure and sound field opening angle of the sensor. Taking the above conditions into consideration, the diameter of the piezoelectric ceramic column 100 is selected to be 0.45mm. This embodiment is only used as an example and is not limited to this. In other embodiments, it can be adjusted according to actual needs.

[0082] Figure 7 FIG2 shows a flow chart of a method for preparing a piezoelectric material B in another embodiment of the present invention.

[0083] See Figure 7 Combined with Figure 2 、 Figure 3 and Figure 4 Another embodiment of the present invention provides a method for preparing a piezoelectric material B, comprising:

[0084] S210 , positioning at least one piezoelectric ceramic column 100 in the mold 20 by the positioning assembly 10 ; defining a pouring cavity 13 for accommodating at least part of the piezoelectric ceramic column 100 between the positioning assembly 10 and the mold 20 .

[0085] S220 , pouring the matrix material 200 into the pouring cavity 13 through a pouring process to wrap the piezoelectric ceramic column 100 located in the pouring cavity 13 ;

[0086] S230, degassing the base material 200 in the perfusion cavity 13 through a degassing process;

[0087] S240, curing the base material 200 through a curing process to form a piezoelectric element A; the piezoelectric element A includes the cured base material 200 and the piezoelectric ceramic column 100 wrapped in the base material 200;

[0088] S250 , cutting the piezoelectric element A into a preset thickness to obtain a piezoelectric material B.

[0089] For details regarding steps S210, S220, S240, and S250, please refer to the aforementioned embodiments and will not be further elaborated here. In step S230, a degassing process is added to the base material 200 before the curing process to prevent bubbles in the base material 200 from interfering with the transmission of sound waves. Alternatively, vacuum degassing or pressure degassing can be employed. Alternatively, degassing agents and defoaming agents can be added to the base material 200, without limitation.

[0090] Figure 8 FIG. 4 is a flow chart showing a method for preparing a piezoelectric material B in another embodiment of the present invention.

[0091] See Figure 8 Combined with Figure 2 、 Figure 3 and Figure 4 Another embodiment of the present invention provides a method for preparing a piezoelectric material B, comprising:

[0092] S310 , positioning at least one piezoelectric ceramic column 100 in the mold 20 by the positioning assembly 10 ; defining a pouring cavity 13 for accommodating at least part of the piezoelectric ceramic column 100 between the positioning assembly 10 and the mold 20 .

[0093] S320, pouring the matrix material 200 into the pouring cavity 13 through a pouring process to wrap the piezoelectric ceramic column 100 located in the pouring cavity 13;

[0094] S330, curing the base material 200 through a curing process to form a piezoelectric element A; the piezoelectric element A includes the cured base material 200 and the piezoelectric ceramic column 100 wrapped in the base material 200;

[0095] S340, performing polarization processing on the piezoelectric ceramic column 100 along the axial direction of the piezoelectric ceramic column 100;

[0096] S350 , cutting the piezoelectric element A into a preset thickness to obtain a piezoelectric material B.

[0097] Polarization refers to applying a strong DC electric field to the piezoelectric ceramic column 100 so that the electric domains in the ceramic are oriented and arranged along the direction of the electric field, thereby making the piezoelectric ceramic column 100 have piezoelectric properties. In this embodiment, before cutting the piezoelectric element A with a preset thickness to obtain the piezoelectric material B, the piezoelectric ceramic column 100 is polarized in the axial direction so that it has good piezoelectric properties. Of course, the piezoelectric ceramic column 100 can also be polarized in advance before step S310, which is not limited here. It should be noted that in steps S310, S320, S330, and S350, please refer to the contents of some of the aforementioned embodiments for details, which will not be repeated here.

[0098] Specifically, electrode layers are formed on two surfaces of the piezoelectric ceramic column 100 that are perpendicular to the axial direction, so as to polarize the piezoelectric ceramic column 100. More specifically, the electrode layers are plated on two surfaces of the piezoelectric ceramic column 100 that are perpendicular to the axial direction.

[0099] This application uses the lead zirconate titanate piezoelectric ceramic pillars described in some of the aforementioned embodiments as an example. The polarization conditions can be selected as follows: a polarization electric field of 1.5-5 kV / mm, a polarization temperature of 100-180°C, and a polarization time of 10-60 minutes. Of course, the polarization conditions can also be adjusted based on actual needs and material selection, and are not limited here.

[0100] Please refer again Figure 4 Based on the same inventive concept, the present application also provides a piezoelectric material B, which is prepared using the above-mentioned method for preparing the piezoelectric material B.

[0101] A higher thickness electromechanical coupling coefficient and a lower radial electromechanical coupling coefficient can improve the resolution and sensitivity of the ultrasonic sensor. However, due to the limitations of the manufacturing process of the piezoelectric ceramic pillar 100, the thickness electromechanical coupling coefficient of the piezoelectric material B in the related art can only reach 0.48.

[0102] The piezoelectric material B prepared using the above-described method for preparing piezoelectric material B has a thickness electromechanical coupling coefficient ranging from 0.5 to 0.72. Because the matrix material 200 suppresses the radial vibration of the piezoelectric ceramic column 100, its vibration energy is essentially concentrated in the unconstrained thickness direction. Therefore, its thickness electromechanical coupling coefficient can reach a maximum of 0.72. However, due to the inevitable energy loss during the energy conversion process of the piezoelectric ceramic column 100, and as the thickness increases, the matrix material 200 more significantly constrains the piezoelectric ceramic column 100, its thickness electromechanical coupling coefficient will slightly decrease to 0.5.

[0103] The piezoelectric material B preparation method and piezoelectric material B provided in the embodiment of the present application pre-position the piezoelectric ceramic column 100 in the pouring cavity 13 of the mold 20 through the positioning component 10, and then pour the matrix material 200 into the piezoelectric ceramic column 100 to wrap it. This allows the piezoelectric ceramic column 100 to be positioned in a preset manner in the matrix material 200, thereby enabling the piezoelectric ceramic column 100 in the piezoelectric material B to be accurately positioned as required. Moreover, the piezoelectric material B prepared by this piezoelectric material B preparation method, because the piezoelectric ceramic column 100 in the piezoelectric material B is wrapped by the matrix material 200, limits the radial vibration of the piezoelectric ceramic column 100. Therefore, compared with the piezoelectric material B in the related art, the piezoelectric material B in the present application has a thickness electromechanical coupling coefficient of 0.5-0.72.

[0104] It should be noted that some of the technical solutions described above can be implemented as independent embodiments in the actual implementation process, or they can be combined with each other and implemented as combined embodiments. Some of the technical solutions described above are exemplary solutions. How to combine them for implementation can be selected according to actual needs, and the embodiments of the present application are not specifically limited. In addition, when the contents of the above-mentioned embodiments of the present application are described, different embodiments are described in the corresponding order based on the idea of convenient description, such as the order preset according to the requirements in the actual implementation process, rather than limiting the execution order between different embodiments. Accordingly, in the actual implementation process, if it is necessary to implement multiple embodiments provided by the embodiments of the present application, it is not necessarily necessary to follow the execution order provided when the embodiments are described in the present invention, but the execution order between different embodiments can be arranged according to demand.

[0105] It should be understood that although Figure 1 、 Figure 5 、 Figure 7 and Figure 8 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. In addition, Figure 1 、 Figure 5 、 Figure 7 and Figure 8 At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The order of execution of these steps or stages is not necessarily one by one, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

[0106] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing a piezoelectric material, characterized in that: include: The positioning assembly includes a first positioning member and a second positioning member; the two ends of the piezoelectric ceramic column along its axial direction are fixed to the first positioning member and the second positioning member according to preset positions respectively; The mold has a receiving cavity with an opening at one end, and the receiving cavity has a bottom wall opposite to the opening; one of the first positioning member and the second positioning member is placed on the bottom wall, so that the other of the first positioning member and the second positioning member blocks the opening to form a pouring cavity; The other of the first positioning member and the second positioning member is provided with a through hole capable of communicating with the perfusion cavity; on a side of the other of the first positioning member and the second positioning member facing away from one of the other, a matrix material is poured into the perfusion cavity through the through hole by a perfusion process to wrap the piezoelectric ceramic column located in the perfusion cavity; solidifying the base material through a curing process to form a piezoelectric element; The piezoelectric element includes the solidified matrix material and the piezoelectric ceramic column wrapped in the matrix material; The piezoelectric element is cut into pieces with a predetermined thickness to obtain the piezoelectric material.

2. The method for preparing a piezoelectric material according to claim 1, wherein: There are multiple piezoelectric ceramic columns; The plurality of piezoelectric ceramic columns are regularly arranged relative to the positioning assembly; or the plurality of piezoelectric ceramic columns are irregularly arranged relative to the positioning assembly.

3. The method for preparing a piezoelectric material according to claim 1, wherein: The orthographic projection of the piezoelectric ceramic column on a plane perpendicular to the axial direction of the piezoelectric ceramic column is a first projection; the shape of the first projection includes a circle, a square or a polygon; and / or The orthographic projection of the matrix material on a plane perpendicular to the axial direction of the piezoelectric ceramic column is a second projection; the shape of the second projection includes a circle, a square or a polygon.

4. The method for preparing a piezoelectric material according to claim 1, wherein: The preset thickness range is 0.1mm-10mm.

5. The method for preparing a piezoelectric material according to claim 1, wherein: The positioning component is made of the same material as the base material.

6. A piezoelectric material, characterized in that: The piezoelectric material is prepared by the piezoelectric material preparation method according to any one of claims 1 to 5.

7. The piezoelectric material according to claim 6, wherein The thickness electromechanical coupling coefficient of the piezoelectric material is in the range of 0.5-0.72.

Images