High-power sandwich type piezoelectric composite material underwater acoustic transducer and preparation method thereof

Abstract

The invention discloses a high-power sandwich type piezoelectric composite material underwater acoustic transducer and a preparation method thereof, and relates to the technical field of underwater acoustic detection. According to the sandwich type piezoelectric composite material underwater acoustic transducer provided by the invention, through the sandwich type design of the front cover plate, the piezoelectric composite material and the rear cover plate, heat generated by the piezoelectric composite material element is efficiently transferred into water, so that the defect that the temperature is high when an existing piezoelectric composite material transducer works at high power is overcome; the temperature of the piezoelectric composite material transducer is reduced, and meanwhile the working stability of the piezoelectric composite material transducer under high power can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater acoustic detection, and in particular to a high-power sandwich-type piezoelectric composite underwater acoustic transducer and a preparation method thereof. Background Art

[0002] Piezoelectric composites are a type of piezoelectric material that has emerged in recent decades. They are composed of a piezoelectric phase and a polymer phase. This composite not only improves the piezoelectric properties of single-phase piezoelectric materials, but also has excellent properties that single-phase piezoelectric materials do not have. Type 1-3 piezoelectric composites are commonly used as sensitive elements for transducers. They are widely used in the fields of underwater acoustics and industrial ultrasound because of their high electromechanical conversion efficiency and good high-frequency vibration characteristics.

[0003] In the field of underwater acoustics, transducers are usually required to work under high electrical power to increase the intensity of sound waves radiated by the transducer. However, piezoelectric composite materials have the disadvantages of large mechanical loss and dielectric loss. This leads to a significant temperature rise under high power operation, which seriously affects the performance of radiating sound waves. Therefore, in order to make piezoelectric composite transducers adapt to the needs of high power operation, it is necessary to improve the heat dissipation capacity of such transducers.

[0004] At present, there are two cooling methods for high-power transducers: air cooling and liquid cooling. Air cooling is a widely used cooling method due to its simple structure and low cost. Its working principle is to reduce the temperature by increasing the contact area with the air. Air cooling is often used in ultrasonic welding, ultrasonic cleaning and other fields. However, due to the low specific heat capacity of air, the air cooling system requires a large contact area to achieve the ideal cooling effect, which makes it difficult to apply to small transducers. Compared with air cooling, liquid cooling has higher cooling efficiency. Liquid cooling sintered the liquid with high thermal conductivity into the metal shell and took away the heat through the flow of liquid. For piezoelectric composite underwater acoustic transducers, its working medium is liquid water with a large specific heat capacity, and water itself is a good coolant. Therefore, as long as the heat generated by the piezoelectric composite material is promptly exported to the transducer surface, the water medium can quickly absorb the heat. Summary of the invention

[0005] The purpose of the present invention is to provide a high-power sandwich piezoelectric composite underwater acoustic transducer and a preparation method thereof, so as to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a sandwich piezoelectric composite underwater acoustic transducer, which is characterized by comprising a three-layer structure of a front cover plate, a piezoelectric composite material and a rear cover plate connected in sequence;

[0008] The front cover plate, the piezoelectric composite material and the rear cover plate are connected by one or more prestressed bolts.

[0009] Furthermore, the piezoelectric composite material is in the shape of a plane, a curved surface, a crown surface or a spherical surface, and correspondingly, the front cover plate and the rear cover plate are in the shape of a plane, a curved surface, a crown surface or a spherical surface.

[0010] Furthermore, the piezoelectric composite material includes a piezoelectric ceramic composite material (i.e., a piezoelectric ceramic / polymer composite material), a piezoelectric single crystal composite material (i.e., a piezoelectric single crystal / polymer composite material) or a textured ceramic composite material (textured ceramic / polymer composite material), such as a type 1-3 piezoelectric composite material, a type 2-2 piezoelectric composite material, etc.

[0011] Furthermore, the piezoelectric composite material is a multi-layer structure.

[0012] Furthermore, the material of the front cover plate includes a light metal material or a light non-metal material; the material of the rear cover plate includes a heavy metal material or a non-metal material.

[0013] The light metal material includes aluminum alloy, titanium alloy or magnesium alloy; the heavy metal material includes steel or copper; and the light non-metal material includes graphite.

[0014] Furthermore, the material of the prestressed bolts is metal.

[0015] Furthermore, the total thickness of the front cover plate and the rear cover plate is twice the thickness of the piezoelectric composite material.

[0016] Furthermore, the front cover plate, the piezoelectric composite material and the rear cover plate are isolated by a heat-conducting insulating layer.

[0017] Furthermore, the thermally conductive insulating layer includes a thermally conductive insulating material and an adhesive (used for bonding the front cover plate and the rear cover plate to the thermally conductive insulating layer); the thermally conductive insulating material can be selected from materials such as acrylic sheet or silicone grease; the adhesive can be selected from polymer solutions such as epoxy resin, silicone rubber, polyimide, etc.

[0018] Furthermore, the hole between the prestressed bolt and the piezoelectric composite material is filled with a thermally conductive and insulating polymer material.

[0019] In the present invention, a temperature monitoring sensor may be arranged between the front cover plate, the piezoelectric composite material and the rear cover plate to observe temperature changes.

[0020] The present invention also provides a method for preparing the sandwich piezoelectric composite underwater acoustic transducer, comprising the following steps:

[0021] (1) Designing and preparing the piezoelectric composite material, the front cover plate, the rear cover plate and the prestressed bolts of corresponding sizes;

[0022] (2) providing a thermally conductive insulating layer on the upper and lower surfaces of the piezoelectric composite material, and placing a front cover plate and a rear cover plate in contact with the thermally conductive insulating layers on the upper and lower surfaces of the piezoelectric composite material, respectively, and using the prestressed bolts to penetrate the front cover plate, the piezoelectric composite material, the rear cover plate, and the thermally conductive insulating layers provided on the upper and lower surfaces of the piezoelectric composite material;

[0023] (3) The device obtained in step (2) is encapsulated with a waterproof material to obtain the sandwich piezoelectric composite underwater acoustic transducer.

[0024] The waterproof material includes polymer composite materials such as polyurethane, epoxy resin, silicone rubber, etc.

[0025] Furthermore, the preparation process also includes the step of filling the gap between the prestressed bolt and the piezoelectric composite material with a thermally conductive insulating polymer material.

[0026] Furthermore, polymer materials such as silicone grease, silicone oil, epoxy resin, silicone rubber, polyurethane or polyimide may be used.

[0027] Furthermore, the sizes of the front and rear cover plates can be adjusted according to the potting conditions required during the preparation process.

[0028] The present invention discloses the following technical effects:

[0029] The present invention provides a sandwich piezoelectric composite underwater acoustic transducer. Through the sandwich design of front cover plate-piezoelectric composite material-rear cover plate, the heat generated by the piezoelectric composite material element is efficiently transferred to the water, which makes up for the defect of high temperature of the existing piezoelectric composite material transducer under high power operation, reduces the temperature of the piezoelectric composite material transducer, and at the same time can increase the stability of the piezoelectric composite material transducer working under high power. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 The present invention is a schematic structural diagram of a sandwich-type piezoelectric composite underwater acoustic transducer.

[0032] Figure 2 It is a schematic structural diagram of another sandwich-type piezoelectric composite underwater acoustic transducer of the present invention.

[0033] Figure 31 is a graph showing average temperature and input power of three sandwich piezoelectric composite transducers with different cover plate thicknesses in Example 1 of the present invention.

[0034] Figure 4 Graphs showing the sound source level and input power of sandwich piezoelectric composite transducers with three different cover plate thicknesses in Example 1 of the present invention.

[0035] Figure 5 This is a curve diagram of average temperature and input power of sandwich piezoelectric composite material and non-sandwich piezoelectric composite material transducer in Example 1 of the present invention.

[0036] Figure 6 This is a curve diagram of the sound source level and input power of the sandwich piezoelectric composite material and the non-sandwich piezoelectric composite material transducer in Example 1. DETAILED DESCRIPTION

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0039] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0040] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0041] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0042] Example 1

[0043] Embodiment 1 provides a planar sandwich piezoelectric composite underwater acoustic transducer; wherein, the front cover plate is made of aluminum alloy, the rear cover plate is made of steel, and the piezoelectric composite material is a composite of PZT-5A piezoelectric ceramic and 618 epoxy resin.

[0044] In order to better design the sandwich piezoelectric composite underwater acoustic transducer, three sandwich piezoelectric composite transducers with different cover plate thicknesses were prepared experimentally. The dimensional parameters of each part of the experimentally prepared sandwich piezoelectric composite underwater acoustic transducer are shown in Table 1.

[0045] Table 1 Dimensional parameters of each part of the transducer

[0046]

[0047] Note: Except for the different sizes of piezoelectric composite materials, front cover and rear cover, the other parameters of prototypes 1 to 3 are the same.

[0048] In Example 1 of the present invention, the piezoelectric composite material, the front cover plate, the rear cover plate and the prestressed bolts are assembled to obtain a sandwich piezoelectric composite underwater acoustic transducer, and the steps are as follows:

[0049] (1) Design and prepare piezoelectric composite materials, front cover plates, rear cover plates and prestressed bolts of corresponding sizes;

[0050] (2) drilling holes in the piezoelectric composite material prepared in step (1), placing acrylic sheets on the upper and lower surfaces of the piezoelectric composite material, and then bonding the front cover plate and the rear cover plate to the corresponding surfaces of the acrylic sheets using epoxy resin;

[0051] (3) Use prestressed bolts to penetrate the front cover plate, the acrylic thin plate composite piezoelectric material arranged on the upper surface of the composite piezoelectric material, the acrylic thin plate arranged on the lower surface of the composite piezoelectric material, and the rear cover plate in sequence for fixing; and fill the gap between the prestressed bolts and the piezoelectric composite material with 618 epoxy resin.

[0052] (4) Using waterproof material (polyurethane) to encapsulate the device of step (3) to obtain a sandwich piezoelectric composite underwater acoustic transducer.

[0053] The sandwich piezoelectric composite underwater acoustic transducer with three different cover thicknesses was tested with the test water temperature at 20°C. The test results are shown in Figure 3 , 4As shown. Since the thickness, material and total length of the front and rear covers have a certain influence on the acoustic performance of the sandwich transducer, in order to make the sandwich transducer have better acoustic performance, the total thickness of the front and rear covers is kept unchanged during the experiment, that is, the thickness of the piezoelectric composite material is 1 / 3 of the total length of the transducer.

[0054] It can be seen from the test results that the average temperature of the sandwich piezoelectric composite underwater acoustic transducer increases rapidly with the increase of the transducer input power. The influence of the front and rear cover plates of three different thicknesses on the temperature of the sandwich piezoelectric composite transducer is relatively limited. When the input power is 400-500W, the maximum temperature difference is only 3.1℃. In terms of acoustic performance, the thickness of the front and rear cover plates has a more obvious effect on the sound source level. As the input power increases, the sound source level continues to increase. During the increase, the sound source level of the sandwich piezoelectric composite transducer with a front cover of 4mm and a rear cover of 12mm gradually widens from the sandwich transducers with the other two thicknesses of front and rear cover plates. The gap is the largest when the input power is the largest.

[0055] Considering the thermal stability and acoustic performance of the three sandwich piezoelectric composite transducers, the sandwich piezoelectric composite transducer with a front cover thickness of 4mm and a rear cover thickness of 12mm has the best performance, and it is compared with the non-sandwich piezoelectric composite transducer to determine the advantages of the sandwich piezoelectric composite transducer under high power operation. Among them, the difference between the non-sandwich piezoelectric composite transducer and the sandwich piezoelectric composite transducer (front cover thickness of 4mm, rear cover thickness of 12mm) is that there is no front cover, rear cover, prestressed bolts and insulation layer, and polyurethane is used for potting, and the rest of the materials and dimensions are the same.

[0056] Figure 5 and Figure 6 Figure 2 is the relationship curve between the average temperature, sound source level and input power of the two transducers.

[0057] exist Figure 5 It can be seen that the temperature of the sandwich piezoelectric composite transducer and the non-sandwich piezoelectric composite transducer increases nonlinearly with the power. When the input power is 200-300W, the temperature difference between the two is about 10℃. When the input power exceeds 300W, the temperature difference gradually widens, reaching 40.1℃ at 500W. Figure 6 When the input power is less than 300W, the sound source level of the sandwich piezoelectric composite transducer is slightly lower than that of the non-sandwich transducer. When the input power exceeds 300W, the temperature of the non-sandwich transducer rises sharply and the acoustic performance decreases. The acoustic performance gap between the two gradually narrows. When the input power is greater than 400W, the sound source level of the sandwich piezoelectric composite transducer surpasses that of the non-sandwich transducer. When the input power is 500W, the sound source level of the sandwich piezoelectric composite transducer is 2.4dB higher than that of the non-sandwich transducer.

[0058] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A sandwich piezoelectric composite underwater acoustic transducer, characterized in that: It includes a three-layer structure of a front cover plate, a piezoelectric composite material and a rear cover plate connected in sequence; The front cover plate, the piezoelectric composite material and the rear cover plate are connected by one or more prestressed bolts.

2. The sandwich piezoelectric composite underwater acoustic transducer according to claim 1 is characterized in that: The piezoelectric composite material is in the shape of a plane, a curved surface, a crown surface or a spherical surface, and correspondingly, the front cover plate and the rear cover plate are in the shape of a plane, a curved surface, a crown surface or a spherical surface.

3. The sandwich piezoelectric composite underwater acoustic transducer according to claim 1 is characterized in that: The piezoelectric composite material includes a piezoelectric ceramic composite material, a piezoelectric single crystal composite material or a textured ceramic composite material.

4. The sandwich piezoelectric composite underwater acoustic transducer according to claim 1, characterized in that: The piezoelectric composite material is a multi-layer structure.

5. The sandwich piezoelectric composite underwater acoustic transducer according to claim 1, characterized in that: The material of the front cover plate includes a light metal material or a light non-metal material; the material of the rear cover plate includes a heavy metal material or a non-metal material; and the material of the prestressed bolt is metal.

6. The sandwich piezoelectric composite underwater acoustic transducer according to claim 1, characterized in that: The total thickness of the front cover plate and the rear cover plate is twice the thickness of the piezoelectric composite material.

7. The sandwich piezoelectric composite underwater acoustic transducer according to claim 1, characterized in that: The front cover plate, the piezoelectric composite material and the rear cover plate are isolated by a heat-conducting insulating layer.

8. The sandwich piezoelectric composite underwater acoustic transducer according to claim 7, characterized in that: The gap between the prestressed bolt and the piezoelectric composite material is filled with a thermally conductive and insulating polymer material.

9. The sandwich piezoelectric composite underwater acoustic transducer according to claim 1, characterized in that: A temperature monitoring sensor is arranged between the front cover plate, the piezoelectric composite material and the rear cover plate.

10. The method for preparing a sandwich piezoelectric composite underwater acoustic transducer according to claim 7, characterized in that: The following steps are involved: (1) Designing and preparing the piezoelectric composite material, the front cover plate, the rear cover plate and the prestressed bolts of corresponding sizes; (2) providing a thermally conductive insulating layer on the upper and lower surfaces of the piezoelectric composite material, and placing a front cover plate and a rear cover plate in contact with the thermally conductive insulating layers on the upper and lower surfaces of the piezoelectric composite material, respectively, and using the prestressed bolts to penetrate the front cover plate, the piezoelectric composite material, the rear cover plate, and the thermally conductive insulating layers provided on the upper and lower surfaces of the piezoelectric composite material; (3) The device obtained in step (2) is encapsulated with a waterproof material to obtain the sandwich piezoelectric composite underwater acoustic transducer.

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