A transmitting transducer for acoustic logging while drilling and a method of manufacturing the same

Abstract

The application discloses a drill-while-sounding acoustic logging transmitting transducer and a preparation method thereof, and comprises the following steps: 1) preparing a tile-shaped piezoelectric element from bismuth scandate lead titanate-based high-temperature piezoelectric material; 2) preparing a tile-shaped bearing framework with a rectangular array of air slots from polyimide (PI); 3) sequentially clamping the tile-shaped piezoelectric element obtained in step 1 into the rectangular air slots of the tile-shaped bearing framework obtained in step 2; 4) connecting electrical leads to the tile-shaped piezoelectric element to obtain a transducer embryo; and 5) vacuum potting and overall solidifying the transducer embryo obtained in step 4 to obtain the drill-while-sounding acoustic logging transmitting transducer. The transducer and the preparation method thereof have the characteristics of low processing difficulty, high yield, strong impact resistance, low overall failure risk and stable performance under variable temperature conditions.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature logging technology and relates to a logging-while-drilling acoustic transducer and its preparation method. Background Technology

[0002] As a core technology in oil and gas exploration and development, sonic logging while drilling (SWP) plays a crucial role in real-time geological steering, detailed formation parameter evaluation, and complex reservoir characterization. Compared to conventional wireline logging, SWP offers significant advantages in shortening drilling cycles, reducing overall production costs, and improving the timeliness of reservoir evaluation due to its ability to acquire downhole characteristic information in real time. However, as modern drilling engineering progresses towards deeper and ultra-deeper formations with complex geological targets, the downhole operating environment for SWP instruments is becoming increasingly extreme. In actual operations, in addition to enduring severe vibrations, strong mechanical shocks, and high-speed erosion from drilling fluids over extended periods, the instrument system faces the severe challenge of combined ultra-high temperature and ultra-high pressure (HTHP). This extreme physical environment places extremely high demands on the stable reception and electromechanical conversion of downhole acoustic signals, making existing technologies prone to sudden performance degradation or structural failure under high temperature and pressure conditions. Therefore, developing downhole acoustic signal receiving technology that can adapt to the complex and harsh working conditions of deep wells and has high reliability and high sensitivity has become a technical bottleneck that urgently needs to be overcome in this field.

[0003] Currently, piezoelectric elements in domestic and international drilling acoustic logging transducers generally adopt a monolithic tile-like structure. This structure requires sintering the piezoelectric ceramic and then directly cutting and grinding it to produce tiles with regular inner and outer diameters and dimensions. However, due to the extreme difficulty in processing large-sized monolithic ceramics, the edge chipping rate during processing is extremely high, resulting in a very low overall processing yield of the piezoelectric element. In addition, in the complex downhole operating environment, the monolithic tile-like structure has poor pressure resistance and is prone to stress concentration when subjected to severe drill string vibration and mechanical impact, leading to brittle fracture and fragmentation of the ceramic. More critically, because it adopts a monolithic structure, any minor local damage can directly lead to the complete failure and scrapping of the entire transducer. Therefore, developing a high-reliability composite piezoelectric element with high processing yield, high pressure resistance, and impact resistance is particularly important, as this will directly determine whether drilling acoustic logging instruments can stably acquire formation acoustic signals for a long period under extreme conditions.

[0004] However, the aforementioned existing technologies have the following drawbacks: 1) Extremely difficult processing and low yield: After sintering, the monolithic piezoelectric ceramic must undergo complex cutting and grinding processes to be processed into a tile shape with regular inner and outer diameters and dimensions. During this process, edge chipping is very likely to occur, resulting in a high scrap rate; 2) Poor pressure resistance and extremely poor impact resistance: When facing ultra-high pressure (such as 100~200 MPa) downhole and strong mechanical vibration and impact from drilling tools, the large-size monolithic tile structure is prone to stress concentration, which can lead to brittle fracture and breakage of the ceramic body; 3) Low fault tolerance of monolithic structure and risk of overall failure: Due to the use of monolithic structure, any local minor damage or micro-cracks will directly damage its electrical and acoustic performance, ultimately leading to the complete failure and scrapping of the entire transducer; 4) Rapid performance degradation under variable temperature conditions: When operating downhole, the transducer faces drastic temperature changes from room temperature to extreme high temperatures. Traditional frameless / monolithic piezoelectric structures lack effective thermomechanical stress constraints, and thermal expansion mismatch at high temperatures leads to a sharp decline in their electromechanical conversion efficiency, severely reducing their effective service temperature limit in deep wells. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a logging-while-drilling sonic transducer and its preparation method. The transducer and its preparation method have the characteristics of low processing difficulty, high yield, strong impact resistance, low overall failure risk, and relatively stable performance under variable temperature conditions.

[0006] To achieve the above objectives, this invention discloses a method for preparing a logging-while-drilling (LWD) acoustic transducer, comprising: 1) Fabrication of tile-shaped piezoelectric elements using bismuth scandate and lead titanate-based high-temperature piezoelectric materials; 2) A tile-shaped support frame with a rectangular array of empty slots was prepared using polyimide (PI); 3) Insert the tile-shaped piezoelectric elements obtained in step 1) into the rectangular slots of the tile-shaped support frame obtained in step 2); 4) Connect electrical leads to the tile-shaped piezoelectric element to obtain the transducer blank; 5) Vacuum potting and overall solidification are performed on the transducer blank obtained in step 4) to obtain the logging-while-drilling sonic transducer.

[0007] Furthermore, the specific operation of step 1) is as follows: 11) Obtain a high-temperature piezoelectric ceramic block, wherein the high-temperature piezoelectric ceramic block is selected from bismuth scandate and lead titanate-based high-temperature piezoelectric materials; 12) Polish and thoroughly clean the surface of the obtained high-temperature piezoelectric ceramic block, and then grind it to the preset thickness; 13) Apply a silver paste layer evenly to the upper and lower surfaces of the polished high-temperature piezoelectric ceramic block, heat it up and keep it at that temperature, then let it cool naturally to room temperature, and then perform high-pressure polarization treatment on the high-temperature piezoelectric ceramic block. 14) Cut the polarized high-temperature piezoelectric ceramic block into a preset size to obtain a tile-shaped piezoelectric element.

[0008] Furthermore, the thickness of the silver paste layer is 0.01–0.03 mm.

[0009] Furthermore, the heat preservation temperature is 850℃, and the heat preservation time is 30 minutes.

[0010] Furthermore, the preset thickness is 4-5mm.

[0011] Furthermore, polyimide can be processed into tile-shaped load-bearing skeletons using machining or 3D printing methods.

[0012] Further, the specific operation of step 5) is as follows: use epoxy resin to fully fill the gap between the tile-shaped support frame and the tile-shaped piezoelectric element, let it stand, then perform vacuum degassing treatment to remove air bubbles, and finally cure it under gradient high temperature to release the initial thermal stress and obtain the drilling acoustic logging transmitter transducer.

[0013] Furthermore, after standing at room temperature for 1 hour, the entire system is then subjected to vacuum degassing to remove air bubbles.

[0014] Furthermore, the tile-shaped support frame has a hollow structure, and the cross-section of the tile-shaped support frame has a circular structure.

[0015] This invention discloses a logging-while-drilling (LWD) acoustic transducer, comprising a tile-shaped support frame with several rectangular slots. Tile-shaped piezoelectric elements are embedded in the rectangular slots, and epoxy resin is disposed between the tile-shaped piezoelectric elements and the inner wall of the rectangular slots. The tile-shaped support frame is made of polyimide (PI), and the tile-shaped piezoelectric elements are made of bismuth scandate-lead titanate-based high-temperature piezoelectric material.

[0016] The present invention has the following beneficial effects: In the specific operation of the ultrasonic logging transducer and its preparation method described in this invention, epoxy resin is disposed between the tile-shaped piezoelectric element and the inner wall of the rectangular slot. The tile-shaped support skeleton is made of polyimide (PI), and the tile-shaped piezoelectric element is made of bismuth scandate-lead titanate-based high-temperature piezoelectric material. Polyimide has extremely high mechanical strength at high temperatures, which can strongly couple all the dispersed tile-shaped piezoelectric elements into a whole, ensuring that the skeleton will not soften and cause the ceramic array elements to decouple and become unstable at extreme high temperatures of 200°C. In addition, polyimide has an ultra-low and nearly linear coefficient of thermal expansion, which is highly matched with the coefficient of thermal expansion of high-temperature piezoelectric ceramics, fundamentally eliminating the risk of interfacial shear stress and transducer failure caused by thermal expansion mismatch of heterogeneous materials at high temperatures. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the rectangular piezoelectric ceramic array shown in this invention; Figure 2 This is a schematic diagram of the skeleton shown in the present invention; Figure 3 A schematic diagram showing the piezoelectric ceramic mounted on a frame and electrically connected. Figure 4 This is a schematic diagram of the final product encapsulated with epoxy resin. Figure 5 This is a schematic diagram showing the tensile strength of PI at various temperatures; Figure 6 This is a schematic diagram showing the tensile strength of various skeleton materials at high temperatures; Figure 7 A schematic diagram showing the deformation of various skeleton materials as a function of temperature; Figure 8 A schematic diagram showing the coefficients of thermal expansion of various skeleton materials; Figure 9 The temperature performance curves of the comparative transducer (without a frame) are shown. Figure 10 This is a temperature performance curve of the transducer shown in this invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0021] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0022] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0023] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0024] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0027] Example 1 The ultrasonic logging transmitter of the present invention includes a tile-shaped support frame with a plurality of rectangular slots. A tile-shaped piezoelectric element is embedded in the rectangular slot. Epoxy resin is disposed between the tile-shaped piezoelectric element and the inner wall of the rectangular slot. The tile-shaped support frame is made of polyimide (PI), and the tile-shaped piezoelectric element is made of bismuth scandate-lead titanate-based high-temperature piezoelectric material.

[0028] Example 2 The method for preparing the acoustic logging transducer of the present invention includes the following steps: 1) Fabrication of tile-shaped piezoelectric elements; The specific operation of step 1) is as follows: 11) Obtain a high-temperature piezoelectric ceramic bulk material with high Curie temperature and high depolarization temperature prepared by solid-state method, wherein, for different downhole temperature requirements, the high-temperature piezoelectric ceramic bulk material is selected from bismuth scandate-lead titanate (BS-PT) high-temperature piezoelectric material. 12) Polish and thoroughly clean the obtained high-temperature piezoelectric ceramic block to remove oil and impurities, and then grind the high-temperature piezoelectric ceramic block to a preset thickness; preferably, according to the acoustic design requirements of the drilling acoustic transducer, the preset thickness is controlled at 4-5 mm. 13) Silver polarization treatment: A silver paste layer with a thickness of 0.01 to 0.03 mm is uniformly coated on the upper and lower surfaces of the polished ceramic block, and then placed in a resistance furnace and kept at 850°C for 30 minutes. After natural cooling to room temperature, the ceramic block is then subjected to high-voltage polarization treatment; preferably, the piezoelectric constant of the BS-PT ceramic after polarization reaches more than 450 pC / N. 14) Use a dicing machine to cut the polarized ceramic block into a preset size to obtain a tile-shaped piezoelectric element, wherein the preset size is set according to the circumferential azimuth angle and axial dimension requirements of the target transducer; 2) Prepare a tile-shaped support frame with rectangular array slots; The specific manufacturing process includes: machining or 3D printing polyimide (PI) into an arc-shaped skeleton. Preferably, polyimide (PI) is chosen instead of other conventional engineering plastics (such as PEEK, PA, or PU) because PI has a high decomposition temperature of up to 550℃ and an extremely low coefficient of linear thermal expansion (CTE), approximately 51 ppm / ℃. This is very close to the coefficient of thermal expansion of piezoelectric ceramics (approximately 10 ppm / ℃), allowing the PI skeleton to act as a perfect thermal stress buffer layer in variable temperature environments. To ensure assembly flatness, the difference between the inner and outer diameters of the tile-shaped skeleton (i.e., the skeleton groove depth) must be consistent with the thickness of the high-temperature piezoelectric ceramic block. 3) Modular embedding and arrangement: The tile-shaped piezoelectric elements obtained in step 1) are sequentially inserted into the rectangular slots of the tile-shaped support frame obtained in step 2) and arranged neatly, so that the tile-shaped piezoelectric elements are combined to form a whole tile-shaped piezoelectric element with high structural strength under the physical support of the tile-shaped support frame. 4) Connect the electrical leads to the tile-shaped piezoelectric elements obtained in step 3). Specifically, use high-temperature resistant wires or flexible electrodes to lead out the electrodes of each tile-shaped piezoelectric element embedded in the tile-shaped support frame and make electrical connections to obtain the transducer blank. 5) Vacuum potting and overall solidification are performed on the transducer blank obtained in step 4) to obtain the logging-while-drilling sonic transducer.

[0029] High-temperature resistant, high-performance epoxy resin, which matches the thermal expansion coefficient of the skeleton and ceramic, is selected to fully fill the gap between the tile-shaped load-bearing skeleton and the tile-shaped piezoelectric element. After standing at room temperature for 1 hour, the whole thing is placed in a vacuum chamber for vacuuming and degassing. Finally, it is cured at a gradient high temperature to release the initial thermal stress and obtain the drilling acoustic logging transmitter transducer.

[0030] It should be noted that the present invention has the following characteristics: The high temperature and rigidity of the polyimide (PI) backbone enable strong coupling of the ceramic array, preventing high-temperature decoupling failure. Specifically, in the high-temperature environment of downhole drilling, conventional polymers soften significantly above certain temperatures. For example, PEEK transitions from brittle to ductile yielding above 150°C, thus losing its rigid constraint on internal components. Figure 5 and Figure 6 The tensile strength test data shows that the polyimide (PI) skeleton selected in this invention has a tensile strength of nearly 120 MPa at room temperature, and even at extreme high temperatures of 200°C, it can still maintain an excellent mechanical strength of up to 60 MPa, far exceeding PEEK, PTFE and PA. This excellent high-temperature rigidity ensures that the dispersed tile-shaped piezoelectric elements are firmly physically locked and acoustically coupled into a high-strength whole, completely eliminating the displacement of ceramic elements and mechanical decoupling caused by thermal softening of the skeleton.

[0031] Polyimide (PI) has an extremely low coefficient of thermal expansion that perfectly matches ceramics, eliminating the high-temperature thermal stress failure mechanism; Specifically, when transitioning from room temperature to extreme high temperatures, traditional encapsulation frameworks (such as PU and PA, with coefficients of thermal expansion as high as 179 ppm / ℃ and 145 ppm / ℃, respectively) experience significant dimensional expansion; even after PEEK exceeds its glass transition temperature, the CTE surges to 180 ppm / ℃. This abrupt expansion exerts devastating shear forces on the ceramic. Figure 7 The deformation curve and Figure 8 As shown in the histogram of thermal expansion coefficients, the PI used in this invention has an ultra-low and nearly linear thermal expansion coefficient of approximately 51 ppm / ℃, and its dimensional deformation is the smallest among all comparative materials. This characteristic makes it highly compatible with high-temperature piezoelectric ceramics, greatly reducing the thermal expansion mismatch stress between heterogeneous interfaces and eliminating the risk of interface delamination and resin cracking at high temperatures.

[0032] The three-dimensional constraint effect of the skeleton significantly improves the stability of the resonant frequency and electroacoustic performance over a wide temperature range; Specifically, traditional frameless transducers are highly susceptible to a sharp drop in piezoelectric performance at high temperatures due to the free release of thermal stress. (Comparison) Figure 9 and Figure 10 The temperature-varying performance curves show that the transducer without a frame ( Figure 9 When the temperature rises to 110°C, the peak conductivity (G) collapses severely, and the resonant frequency shifts drastically to lower frequencies; while the transducer using the PI composite frame shown in this invention ( Figure 10With the three-dimensional adaptive mechanical constraints and thermal stress buffering mechanism provided by the skeleton, it can still maintain an extremely high conductivity resonance peak amplitude when the temperature soars to 180℃, with excellent frequency stability, which greatly expands the extreme temperature resistance range of the transmitting transducer.

[0033] The use of a composite array-based frame structure significantly improves the component's impact resistance and high voltage resistance. This invention breaks through the limitation of traditional single large tiles being prone to stress concentration. The PI load-bearing frame with excellent toughness tightly wraps the piezoelectric ceramic array, which not only effectively buffers the strong mechanical vibration impact during the drilling process, but also enables it to withstand the ultra-high pressure of the formation of 100-200 MPa, thus mitigating the catastrophic risk of the entire transducer being scrapped due to local minor damage.

[0034] By selecting high-temperature piezoelectric materials, the bottleneck of performance degradation under extreme high temperatures has been overcome; Specifically, based on different well logging conditions, this invention employs two piezoelectric materials with high depolarization temperatures to ensure high detection sensitivity of the instrument in extreme environments: Extreme high temperature application: Bismuth scandate lead titanate (BS-PT) high-temperature piezoelectric ceramics are used, with a Curie temperature of up to about 440℃ and extremely high piezoelectric performance ≥ 450 pC / N, ensuring long-term stable operation under extreme ultra-deep well high temperatures.

[0035] Array-based manufacturing processes significantly reduce processing difficulty and enable mass production. Specifically, this invention abandons the high-loss process of directly cutting curved surfaces of large sintered ceramics, instead decomposing complex tile shapes into standard rectangular blocks for cutting and precision assembly. This fundamentally eliminates the problem of ceramic edge chipping, resulting in a simple process and excellent product repeatability. Furthermore, thanks to the high machining precision of the PI skeleton, the array elements are circumferentially evenly distributed, significantly eliminating clutter interference and greatly improving the directional detection capability of acoustic logging.

[0036] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0037] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0038] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a transmitting transducer for acoustic logging while drilling, characterized in that, include: 1) Fabrication of tile-shaped piezoelectric elements using bismuth scandate and lead titanate-based high-temperature piezoelectric materials; 2) A tile-shaped support frame with a rectangular array of empty slots was prepared using polyimide (PI); 3) Insert the tile-shaped piezoelectric elements obtained in step 1) into the rectangular slots of the tile-shaped support frame obtained in step 2); 4) Connect electrical leads to the tile-shaped piezoelectric element to obtain the transducer blank; 5) Vacuum potting and overall solidification are performed on the transducer blank obtained in step 4) to obtain the logging-while-drilling sonic transducer.

2. The method for preparing the acoustic logging transducer according to claim 1, characterized in that, The specific operation of step 1) is as follows: 11) Obtain a high-temperature piezoelectric ceramic block, wherein the high-temperature piezoelectric ceramic block is selected from bismuth scandate and lead titanate-based high-temperature piezoelectric materials; 12) Polish and thoroughly clean the surface of the obtained high-temperature piezoelectric ceramic block, and then grind it to the preset thickness; 13) Apply a silver paste layer evenly to the upper and lower surfaces of the polished high-temperature piezoelectric ceramic block, heat it up and keep it at that temperature, then let it cool naturally to room temperature, and then perform high-pressure polarization treatment on the high-temperature piezoelectric ceramic block. 14) Cut the polarized high-temperature piezoelectric ceramic block into a preset size to obtain a tile-shaped piezoelectric element.

3. The method for preparing the acoustic logging transducer according to claim 2, characterized in that, The thickness of the silver paste layer is 0.01–0.03 mm.

4. The method for preparing the acoustic logging transducer according to claim 2, characterized in that, The heat preservation temperature is 850℃, and the heat preservation time is 30 minutes.

5. The method for preparing the acoustic logging transducer according to claim 2, characterized in that, The preset thickness is 4-5mm.

6. The method for preparing the acoustic logging transducer according to claim 1, characterized in that, Polyimide is processed into tile-shaped load-bearing skeletons using machining or 3D printing.

7. The method for preparing the acoustic logging transducer according to claim 1, characterized in that, Step 5) involves using epoxy resin to fully fill the gap between the tile-shaped support frame and the tile-shaped piezoelectric element. After standing, the entire structure is then vacuumed to remove air bubbles. Finally, it is cured at a gradient high temperature to release the initial thermal stress and obtain the logging-while-drilling transducer.

8. The method for preparing the acoustic logging transducer according to claim 7, characterized in that, After standing at room temperature for 1 hour, the entire system is then vacuumed to remove air bubbles.

9. The method for preparing a logging-while-drilling acoustic transducer according to claim 1, characterized in that, The tile-shaped support frame is a hollow structure, and the cross-section of the tile-shaped support frame is a circular ring structure.

10. A logging-while-drilling acoustic transducer, characterized in that, It includes a tile-shaped support frame with several rectangular slots. Tile-shaped piezoelectric elements are embedded in the rectangular slots. Epoxy resin is placed between the tile-shaped piezoelectric elements and the inner wall of the rectangular slots. The tile-shaped support frame is made of polyimide (PI), and the tile-shaped piezoelectric elements are made of bismuth scandate-lead titanate-based high-temperature piezoelectric material.

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