High-temperature-resistant ultrasonic transducer and manufacturing method thereof

Abstract

The invention provides a high-temperature-resistant ultrasonic transducer and a manufacturing method thereof. The high-temperature-resistant ultrasonic transducer comprises a shell, and a coupling piece, a piezoelectric element, packaging glass, a backing, an electrode block and a pre-tightening block which are arranged in the shell, the coupling piece, the piezoelectric element, the back lining, the electrode block and the pre-tightening block are sequentially arranged from the bottom of the shell to the top, a set gap is formed between the side part of the piezoelectric element, the side part of the back lining and the side part of the electrode block and the inner side wall of the shell, and the packaging glass is arranged in the gap; a counter bore is machined in the center of the bottom of the shell, the diameter of the counter bore is smaller than the inner diameter of the shell, and the distance between the bottom face of the counter bore and the bottom face of the outer side of the shell is one fourth of the wavelength of ultrasonic waves. A wire is arranged on the upper end face of the shell, and a wire is also arranged on the electrode block to serve as the positive electrode and the negative electrode of the transducer. The problems that due to the fact that an existing ultrasonic transducer is poor in high-temperature environment adaptability, the stability of the transducer is poor, the signal transmission efficiency is low, and backward clutters cannot be effectively absorbed are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of transducers, and in particular relates to a high-temperature resistant ultrasonic transducer and a manufacturing method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] When performing non-destructive testing in high-temperature environments, traditional ultrasonic transducers face many technical challenges. In the existing technology, high-temperature transducers are usually composed of components such as a brass shell, a backing layer, a piezoelectric element, a potting material, a microwave high-frequency interface and wires. Among them, the backing layer is mostly made of a mixture of epoxy resin and conductive particles and solidified, while the sealing area relies on high-temperature epoxy potting material. Although this structure can achieve the functions of backing absorption and transducer sealing, due to the limited temperature resistance of epoxy resin and its high thermal expansion coefficient, it is easy for the epoxy resin to soften, fall off or even melt under extremely high temperature conditions, resulting in a decrease in transducer performance or failure. In addition, the difference in thermal expansion coefficient between the epoxy resin and the metal shell may also cause interface delamination, further affecting the sealing and signal stability of the transducer.

[0004] The piezoelectric elements of traditional transducers are usually installed directly in the housing, lacking an effective limiting structure, which may cause the piezoelectric element to contact the housing, resulting in an electrode short circuit. At the same time, if the backing layer is made of non-porous materials, it is difficult to effectively absorb backscatter, thereby interfering with the detection of effective signals. In addition, the preload structure of existing transducers is usually relatively simple, unable to accurately adjust the preload force, and lacks adaptability to thermal expansion effects in high-temperature environments. This can easily lead to loose piezoelectric elements or poor electrode contact, affecting the long-term stability of the transducer and signal transmission efficiency. Summary of the Invention

[0005] In response to the above problems, the present invention provides a high-temperature resistant ultrasonic transducer and a method for manufacturing the same, which solves the problems of poor adaptability of existing ultrasonic transducers to thermal expansion effects in high-temperature environments, resulting in poor transducer stability and low signal transmission efficiency; and the problem of inability to effectively absorb backscattered clutter, thereby interfering with the detection of effective signals.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions: In the first aspect, the present invention provides a high-temperature resistant ultrasonic transducer, comprising: a shell, and a coupling plate, a piezoelectric element, an encapsulation glass, a backing, an electrode block and a pre-tightening block arranged inside the shell; the coupling plate, piezoelectric element, backing, electrode block and pre-tightening block are arranged in sequence from the bottom of the shell upward, and there is a set gap between the side of the piezoelectric element, backing and electrode block and the inner wall of the shell, and the encapsulation glass is arranged in the gap for sealing the piezoelectric element, backing and electrode block; a countersunk hole is processed at the center of the bottom of the shell, the diameter of the countersunk hole is smaller than the inner diameter of the shell, and the distance between the bottom surface of the countersunk hole and the outer bottom surface of the shell is one-quarter of the wavelength of the ultrasonic wave, effectively ensuring the transmission efficiency of the sound wave; a wire is provided on the upper end surface of the shell, and a wire is also provided on the electrode block, which serve as the positive and negative poles of the transducer.

[0007] As a further implementation method, the shell is made of titanium alloy. The shell is a tubular structure with one end closed, which is used to install the coupling plate, piezoelectric element, packaging glass, backing, electrode block and pre-tightening block, and ensure the structural stability of the transducer under high temperature conditions.

[0008] As a further implementation, the coupling piece is made of soft or semi-hard metal foil, which is convenient for filling the gap between the piezoelectric element and the bottom surface of the countersunk hole and reducing the loss of sound wave energy.

[0009] As a further implementation method, the encapsulation glass is made of lead-free low-melting-point glass particles, and the piezoelectric element, backing and electrode block are sealed by sintering and melting the particles.

[0010] As a further implementation method, the piezoelectric element is a disc-shaped structure of suitable frequency made of high-temperature resistant piezoelectric ceramics based on lead zirconate titanate, bismuth titanate or lithium niobate; the operating temperature of the piezoelectric element and the packaging glass cannot be lower than the maximum temperature of the transducer's operating conditions, and the sintering temperature of the packaging glass cannot be higher than the Curie temperature of the piezoelectric element.

[0011] As a further implementation, the backing is a porous metal material, and the porous metal material is a bulk material formed by sintering alloy powder, and is used to reduce interference of clutter on effective signals.

[0012] As a further implementation method, the electrode block consists of a base and a boss, the base is arranged on the backing, the boss is arranged above the base, one end of the wire is connected to the boss, and the boss cooperates with the pre-tightening block to transmit the downward pressing force of the pre-tightening block.

[0013] As a further implementation method, the pre-tightening block consists of an inner tube and an outer tube, the inner tube and the outer tube are fixedly connected by a bracket, the outer wall of the outer tube is connected to the inner wall of the shell by a thread, the boss is inserted into the inner tube, and the end of the inner tube is in contact with the base.

[0014] As a further implementation, a hexagonal bolt head is further provided on the top of the inner tube for adjusting the preload force of the preload block.

[0015] In a second aspect, the present invention further provides a method for manufacturing a high-temperature resistant ultrasonic transducer, comprising the following steps: S1. Select the piezoelectric element and encapsulation glass materials according to the transducer design temperature, and process the components required for transducer assembly according to the design drawings; S2. Before assembly, clean all transducer components. After cleaning, place the coupling plate in the countersunk hole at the bottom center of the housing. Place the piezoelectric element, backing, and electrode block on the top surface of the coupling plate in that order, and finally tighten the preload block. S3. After assembly, pour glass powder into the transducer through the gap between the outer and inner tubes. The amount of glass powder poured should cover half of the electrode block and be lower than the bottom of the electrode block's boss. Shake the glass powder in the transducer to level it. Heat the glass powder at the set temperature to sinter it, sealing the transducer. S4. After sintering is completed, remove the pre-tightening parts and lead out the positive and negative wires of the transducer on the housing and the electrode block boss.

[0016] Compared with the prior art, the present invention has the following advantages and positive effects: The present invention seals the piezoelectric element, backing and electrode block by arranging encapsulating glass in the gap formed between the side of the piezoelectric element, backing and electrode block and the inner wall of the shell. Since the thermal expansion coefficient of the encapsulating glass is low and close to that of the piezoelectric element, the transducer is not prone to piezoelectric element falling off or poor electrode contact at high temperatures, and the performance of the transducer is more stable at high temperatures. A countersunk hole is processed at the center of the bottom of the shell. The diameter of the countersunk hole is smaller than the inner diameter of the shell. The diameter of the countersunk hole is adapted to the diameter of the piezoelectric element, and the depth is less than the thickness of the piezoelectric element, thereby playing a limiting role to prevent the piezoelectric element from contacting the inner wall of the shell and causing a short circuit between the positive and negative poles. The distance between the bottom surface of the countersunk hole and the outer bottom surface of the shell is one-fourth of the wavelength of the ultrasonic wave, effectively ensuring the transmission efficiency of the sound wave.

[0017] The coupling plate of the present invention is made of soft or semi-hard metal foil, such as aluminum, gold, silver, etc., which is convenient for filling the gap between the piezoelectric element and the bottom surface of the countersunk hole to reduce the loss of acoustic wave energy. It can also serve as one pole of the piezoelectric element to transmit the electrical signal to the metal shell; the backing is a porous metal material, and the porous metal material is a block material formed by sintering alloy powder to reduce the interference of noise on the effective signal. The porous structure can effectively absorb noise that diffuses toward the electrode block.

[0018] The pre-tightening block of the present invention is composed of an inner tube and an outer tube, which are fixedly connected by a bracket, and the outer wall of the outer tube is connected to the inner wall of the shell by a thread, the boss is inserted into the inner tube, and the end of the inner tube contacts the base, providing pre-tightening force for the transducer, tightly connecting the components stacked in the layer structure together, and pressing down layer by layer by the pre-tightening block to achieve the purpose of applying pre-tightening force, the size of the pre-tightening force can be adjusted by controlling the distance the pre-tightening block is pressed down or using a torque wrench; the bracket between the inner tube and the outer tube is a hollow structure, which is used to fill glass particles into the gap between the side of the piezoelectric element, backing and electrode block and the inner wall of the shell. Since the pre-tightening block is connected to the shell and the electrode block at the same time, after the transducer is sealed, the pre-tightening block needs to be twisted counterclockwise to prevent the positive and negative poles of the transducer from being short-circuited. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0020] Figure 1 This is a cross-sectional view of the high-temperature resistant ultrasonic transducer of the present invention; Figure 2 This is a top view of the high-temperature resistant ultrasonic transducer of the present invention.

[0021] In the figure: 1. Shell; 2. Coupling plate; 3. Piezoelectric element; 4. Encapsulation glass; 5. Backing; 6. Electrode block; 7. Pre-tightening block; 8. Wire; 9. Outer tube; 10. Bracket; 11. Inner tube; 12. Hexagonal bolt head. DETAILED DESCRIPTION

[0022] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0023] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise clearly indicated in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "comprising" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations; Example 1 This embodiment provides a high temperature resistant ultrasonic transducer, such as Figure 1-Figure 2 As shown, it includes: a shell 1, and a coupling piece 2, a piezoelectric element 3, an encapsulating glass 4, a backing 5, an electrode block 6 and a pre-tightening block 7 arranged inside the shell 1; the coupling piece 2, the piezoelectric element 3, the backing 5, the electrode block 6 and the pre-tightening block 7 are arranged in sequence from the bottom of the shell 1 to the top, and a set gap is formed between the side of the piezoelectric element 3, the backing 5 and the electrode block 6 and the inner wall of the shell 1. The encapsulating glass 4 is arranged in the gap to seal the piezoelectric element 3, the backing 5 and the electrode block 6. Since the thermal expansion coefficient of the encapsulating glass 4 is low and close to that of the piezoelectric element 3, the transducer is not prone to piezoelectric element deformation at high temperatures. 3 falls off, poor electrode contact, etc., and the performance of the transducer is more stable at high temperature; a countersunk hole is processed at the center of the bottom of the shell 1, the diameter of the countersunk hole is smaller than the inner diameter of the shell 1, the diameter of the countersunk hole is adapted to the diameter of the piezoelectric element 3, and the depth is less than the thickness of the piezoelectric element 3, which plays a limiting role to prevent the piezoelectric element from contacting the inner wall of the shell 1 and causing a short circuit between the positive and negative poles; the distance between the bottom surface of the countersunk hole and the outer bottom surface of the shell 1 is one-fourth of the wavelength of the ultrasonic wave, which effectively ensures the transmission efficiency of the sound wave; a wire 8 is provided on the upper end surface of the shell 1, and a wire 8 is also provided on the electrode block 6, which serve as the positive and negative poles of the transducer.

[0024] As a further implementation method, the shell 1 is made of titanium alloy, which can withstand high temperatures of 600°C for a long time, can effectively support and protect the internal components of the transducer, and the thermal expansion coefficient of titanium alloy is relatively small, which is beneficial to the structural stability of the transducer under high temperature. The shell 1 is a tubular structure with one end closed, which is used to install the coupling plate 2, piezoelectric element 3, packaging glass 4, backing 5, electrode block 6 and pre-tightening block 7, and ensure the structural stability of the transducer under high temperature conditions.

[0025] As a further implementation method, the coupling plate 2 is made of soft or semi-hard metal foil, such as aluminum, gold, silver, etc., which is convenient for filling the gap between the piezoelectric element 3 and the bottom surface of the countersunk hole to reduce the loss of sound wave energy. It can also serve as one pole of the piezoelectric element 3 to transmit the electrical signal to the metal shell.

[0026] As a further implementation method, the encapsulating glass 4 is made of lead-free low-melting-point glass particles. The piezoelectric element 3, backing 5 and electrode block 6 are sealed after sintering and melting the particles. The piezoelectric element 3, backing 5 and electrode block 6 can be fixed by the sintered glass, thereby ensuring the sealing effect and insulation performance; at the same time, it can be tolerated for a long time and can withstand thermal shock; since the thermal expansion coefficient of the encapsulating glass 4 is low and close to that of the piezoelectric element 3, the transducer is not prone to problems such as piezoelectric element 3 falling off and poor electrode contact at high temperatures, and the performance of the transducer is more stable at high temperatures.

[0027] As a further implementation method, the piezoelectric element 3 is a key component of the transducer's acoustic-to-electric conversion. The material is selected according to the operating temperature requirements. The piezoelectric element 3 can be selected as a high-temperature resistant piezoelectric ceramic based on lead zirconate titanate, bismuth titanate or lithium niobate, and prepared into a disc-shaped structure of appropriate frequency; the operating temperature of the piezoelectric element 3 and the encapsulating glass 4 cannot be lower than the maximum temperature of the transducer's operating conditions to ensure that the piezoelectric element 3 and the encapsulating glass 4 will not fail during long-term high-temperature use. The sintering temperature of the encapsulating glass 4 cannot be higher than the Curie temperature of the piezoelectric element 3 to ensure that the piezoelectric ceramic will not depolarize during the glass sealing process.

[0028] As a further implementation method, the backing 5 is a porous metal material, which is a block material formed by sintering alloy powder, and is used to reduce the interference of noise on the effective signal. 316L stainless steel or titanium alloy powder with a particle size of less than 1 μm can be selected for sintering. The porous structure can effectively absorb noise that diffuses toward the electrode block 6.

[0029] As a further implementation method, the electrode block 6 consists of a base and a boss, the base is arranged on the backing 5, the boss is arranged above the base, one end of the wire 8 is connected to the boss, and the boss cooperates with the pre-tightening block 7 to transmit the downward clamping force of the pre-tightening block 7.

[0030] As a further implementation, the preload block 7 comprises an inner tube 11 and an outer tube 9, which are fixedly connected via a bracket 10. The outer wall of the outer tube 9 is threadedly connected to the inner wall of the housing 1. The boss is inserted into the inner tube 11, and the end of the inner tube 11 contacts the base. The preload block 7 is made of carbon steel and provides preload force for the transducer, tightly connecting the stacked components together. The preload force is applied layer by layer by pressing down on them with the preload block 7. The preload force can be adjusted by controlling the distance the preload block 7 is pressed down or using a torque wrench. The bracket 10 between the inner tube 11 and the outer tube 9 is surrounded by a hollow structure, which is used to fill glass particles into the gap between the side of the piezoelectric element 3, the backing 5 and the electrode block 6 and the inner wall of the shell 1. Since the pre-tightening block 7 is connected to the shell 1 and the electrode block 6 at the same time, after the transducer is sealed, the pre-tightening block 7 needs to be twisted counterclockwise to prevent the positive and negative poles of the transducer from being short-circuited.

[0031] As a further implementation, a hexagonal bolt head 12 is further provided on the top of the inner tube 11 for adjusting the pre-tightening force of the pre-tightening block 7 and the downward pressing distance of the pre-tightening block 7 .

[0032] Example 2 This embodiment provides a method for manufacturing a high-temperature resistant ultrasonic transducer, comprising the following steps: S1. According to the transducer design temperature, select the piezoelectric element 3 and the encapsulating glass 4 raw materials, and process the components required for transducer assembly according to the design drawings; S2. Before assembly, all transducer components must be cleaned. Ultrasonic cleaning and drying are recommended. After cleaning, place the coupling plate 2 in the countersunk hole at the bottom center of the housing. Place the piezoelectric element 3, backing 5, and electrode block 6 on the upper surface of the coupling plate 2 in that order. Finally, screw on the preload block 7. During assembly, the boss on the upper portion of the electrode block 6 must fit into the through-hole of the inner tube 11 of the preload block 7. When tightening the preload block 7 to apply pressure, the downward pressure can be controlled by adjusting the amount or by using a torque wrench. S3. After assembly is complete, pour glass powder into the transducer through the gap between outer tube 9 and inner tube 11. The amount of glass powder poured should cover half of electrode block 6 and be lower than the bottom of the boss of electrode block 6 to prevent sintering of preload block 7 and transducer. After filling, use a small shaker to shake the glass powder in the transducer to smooth it out and reduce any porosity. Then, sinter the glass powder at the set heat treatment temperature to achieve a sealed transducer. S4. After sintering is completed, the pre-tightening block 7 is removed, and the positive and negative conductors 8 of the transducer are led out from the housing and the boss of the electrode block 6.

[0033] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A high temperature resistant ultrasonic transducer, characterized in that: The invention comprises: a shell, and a coupling piece, a piezoelectric element, an encapsulation glass, a backing, an electrode block and a pre-tightening block arranged inside the shell; the coupling piece, the piezoelectric element, the backing, the electrode block and the pre-tightening block are arranged in sequence from the bottom of the shell upward, and a set gap is provided between the side of the piezoelectric element, the backing and the electrode block and the inner wall of the shell, and the encapsulation glass is provided in the gap to seal the piezoelectric element, the backing and the electrode block; a countersunk hole is processed at the center of the bottom of the shell, the diameter of the countersunk hole is smaller than the inner diameter of the shell, and the distance between the bottom surface of the countersunk hole and the outer bottom surface of the shell is one-fourth of the wavelength of the ultrasonic wave; a wire is provided on the upper end surface of the shell, and a wire is also provided on the electrode block, which serve as the positive and negative poles of the transducer.

2. The high temperature resistant ultrasonic transducer according to claim 1, characterized in that: The shell is made of titanium alloy and is a tubular structure with one end closed. It is used to install the coupling plate, piezoelectric element, packaging glass, backing, electrode block and pre-tightening block, and ensure the structural stability of the transducer under high temperature conditions.

3. The high temperature resistant ultrasonic transducer according to claim 1, characterized in that: The coupling piece is made of soft or semi-hard metal foil.

4. The high temperature resistant ultrasonic transducer according to claim 1, characterized in that: The encapsulating glass is made of lead-free low-melting-point glass particles, and the piezoelectric element, backing and electrode block are sealed by sintering and melting the particles.

5. The high temperature resistant ultrasonic transducer according to claim 4, characterized in that: The piezoelectric element is a disc-shaped structure of suitable frequency made of high-temperature resistant piezoelectric ceramics based on lead zirconate titanate, bismuth titanate or lithium niobate; the operating temperature of the piezoelectric element and the encapsulating glass cannot be lower than the maximum temperature of the transducer's operating conditions, and the sintering temperature of the encapsulating glass cannot be higher than the Curie temperature of the piezoelectric element.

6. The high temperature resistant ultrasonic transducer according to claim 1, characterized in that: The backing is a porous metal material, and the porous metal material is a bulk material formed by sintering alloy powder.

7. The high temperature resistant ultrasonic transducer according to claim 6, characterized in that: The electrode block consists of a base and a boss. The base is arranged on the backing, the boss is arranged above the base, one end of the wire is connected to the boss, and the boss cooperates with the pre-tightening block.

8. The high temperature resistant ultrasonic transducer according to claim 7, characterized in that: The pre-tightening block consists of an inner tube and an outer tube, the inner tube and the outer tube are fixedly connected by a bracket, the outer wall of the outer tube is connected to the inner wall of the shell by a thread, the boss is inserted into the inner tube, and the end of the inner tube is in contact with the base.

9. The high temperature resistant ultrasonic transducer according to claim 8, characterized in that: A hexagonal bolt head is also provided on the top of the inner tube.

10. The method for manufacturing a high temperature resistant ultrasonic transducer according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Select piezoelectric elements and encapsulation glass materials based on the transducer design temperature, and process the components required for transducer assembly; S2. Before assembly, clean all transducer components. After cleaning, place the coupling plate in the countersunk hole at the bottom center of the housing. Place the piezoelectric element, backing, and electrode block on the top surface of the coupling plate in that order, and finally tighten the preload block. S3. After assembly, pour glass powder into the transducer through the gap between the outer and inner tubes. The amount of glass powder poured should cover half of the electrode block and be lower than the bottom of the electrode block's boss. Shake the glass powder in the transducer to level it. Heat the glass powder at the set temperature to sinter it, sealing the transducer. S4. After sintering is completed, remove the pre-tightening parts and lead out the positive and negative wires of the transducer on the housing and the electrode block boss.

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