1-3 type lead metaniobate piezoelectric composite material and preparation method and application thereof

Abstract

The invention belongs to the technical field of functional materials, and particularly relates to a 1-3 type lead metaniobate piezoelectric composite material and a preparation method and application thereof. The composite material takes lead metaniobate ceramic with a tungsten bronze structure as a one-dimensional piezoelectric phase and takes epoxy resin as a three-dimensional polymer phase. The ratio [lambda] / T of the transverse periodic dimension ([lambda]) of the ceramic column to the thickness (T) of the composite material is 0.1-0.6. The preparation method is characterized in that the ceramic column array is formed through precise cutting, cutting parameters are controlled to achieve the lambda / T ratio, and then resin encapsulation, curing, polishing and electrode preparation are conducted. According to the invention, the electromechanical coupling performance and stability of the composite material at ultrahigh temperature are synergistically improved by selecting the lead metaniobate ceramic with high Curie temperature and combining specific lambda / T structural parameters. The obtained material can still keep good performance at 350 DEG C, the maximum thickness electromechanical coupling coefficient kt can reach 0.35, and the material is suitable for high-temperature acoustic logging and underwater acoustic receiving transducers.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of functional materials, and particularly relates to a 1-3 type lead metaniobate piezoelectric composite material and a preparation method and application thereof. BACKGROUND

[0002] Piezoelectric composites, especially 1-3 type piezoelectric composites (consisting of one-dimensional interconnected piezoelectric ceramic columns arranged in parallel in a three-dimensional interconnected polymer matrix), are widely used in hydrophones, ultrasonic transducers and other fields due to their high acoustic impedance matching, high hydrostatic piezoelectric constant and designable vibration mode. In high-temperature application scenarios such as oil acoustic logging, stringent requirements are put forward for the temperature stability of piezoelectric materials.

[0003] At present, the piezoelectric phase of the 1-3 type piezoelectric composite material is mostly lead zirconate titanate (PZT) based ceramics or textured ceramics based on PZT. For example, patent document CN117560986A discloses a 1-3 type textured piezoelectric ceramic composite material, the piezoelectric phase of which is lead magnesium niobate-lead zirconate titanate (PMN-PZT) textured ceramic. By controlling the ratio T / λ of the final thickness (T) of the composite material to the transverse period size (λ) to be between 2.5-3.5, a relatively high thickness electromechanical coupling coefficient (k33 k t >0.8) and piezoelectric constant (d33 d 33 about 730 pC / N) are obtained, which is suitable for underwater acoustic transducers. However, the PMN-PZT based material used in this scheme has a Curie temperature generally not exceeding 360℃, and the maximum use temperature is generally lower than 200℃, which is difficult to meet the extreme environmental requirements of downhole temperature exceeding 300℃ or even 350℃ in deep and ultra-deep oil and gas resource exploration.

[0004] In order to improve the working temperature, the prior art attempts to use piezoelectric materials with higher Curie temperature. Patent document CN117560987A discloses a 1-3 type high-temperature piezoelectric ceramic composite material, the piezoelectric phase of which adopts high-temperature piezoelectric ceramics with bismuth layer structure or perovskite structure (such as bismuth cobalt niobate-lead titanate base), which is prepared by a similar cutting-filling method and controls T / λ to be between 2.8-3.5, and claims that the use temperature can reach 300℃, k t about 0.6. Although this scheme improves the use temperature to 300℃, the specific high-temperature ceramic system used has a relatively high cost, and the k33 k t value is significantly lower than that of the textured PZT composite material in CN117560986A, which means that the receiving sensitivity and energy conversion efficiency at high temperature are compromised. When the application environment requires to reach 350℃ or higher, the performance stability of this material is challenged.

[0005] Lead metaniobate (PbNb2O6, PN for short) ceramic is a tungsten bronze structure ferroelectric, which is known for its extremely high Curie temperature (Tc>557℃) and low mechanical quality factor. It is theoretically a high-potential high-temperature piezoelectric material. However, there is a common technical prejudice in the field that the piezoelectric performance (such as d 33 about 100 pC / N, k t about 0.25) of pure PN ceramic is much lower than that of PZT-based ceramic, and the electromechanical coupling coefficient is too low, resulting in poor sensitivity of the transducer prepared therefrom, which is difficult to meet the requirements of high-performance receiving transducers. Therefore, there is a lack of mature technical solutions in the prior art for successfully applying PN ceramic to 1-3 type composite materials to simultaneously achieve "ultra-high temperature stability" and "sufficiently high receiving sensitivity". How to overcome the performance prejudice of PN ceramic and develop a piezoelectric composite material that can work stably at a temperature of 350℃ or above and has good electromechanical conversion performance through the collaborative design of materials and structure has become a technical problem to be solved in the field. SUMMARY

[0006] The purpose of the present application is to provide a 1-3 type lead metaniobate piezoelectric composite material and its preparation method and application, in order to solve the technical contradiction that the prior art cannot simultaneously maintain excellent temperature stability and high receiving sensitivity at an ultra-high temperature (such as 350℃).

[0007] The technical solution of the present application is: in the first aspect, a 1-3 type lead metaniobate piezoelectric composite material is provided, which comprises a one-dimensional interconnected lead metaniobate piezoelectric ceramic phase and a three-dimensional interconnected polymer phase. The lead metaniobate piezoelectric ceramic phase is an array of lead metaniobate ceramic columns with tungsten bronze structure. The lead metaniobate piezoelectric ceramic phase has a Curie temperature higher than 557℃. The ratio of the lateral period size λ of the ceramic column to the thickness T of the composite material λ / T is 0.1-0.6.

[0008] Preferably, the λ / T is 0.5-0.6.

[0009] Preferably, the volume fraction of the lead metaniobate piezoelectric ceramic phase is 10-90%.

[0010] Preferably, the polymer phase is epoxy resin.

[0011] In the second aspect, a preparation method of a 1-3 type lead metaniobate piezoelectric composite material is provided, which comprises the following steps: S1. providing a lead metaniobate piezoelectric ceramic block; S2. performing a first cutting on the ceramic block in a first direction to form parallel first cutting seams; S3. A second cut is made along a second direction perpendicular to the first direction to form an independent array of lead niobate ceramic pillars; wherein, the cutting parameters are controlled so that the ratio λ / T of the sum of the ceramic pillar width a and the kerf width b to the target thickness T is 0.1-0.6; S4. Fill the gaps in the ceramic column array with a polymer precursor and cure it to form a polymer phase; S5. Grind the blank obtained in step S4, remove excess material from the surface until the target thickness T is reached, and expose the end face of the ceramic column; S6. Prepare a conductive layer on the surface of the polished blank to obtain the composite material.

[0012] Preferably, in step S3, λ / T is 0.5-0.6.

[0013] Preferably, in step S4, the polymer precursor is an epoxy resin colloid; when used in an environment above 200°C, a high-temperature epoxy resin colloid is used and preheated before potting.

[0014] Preferably, in step S6, the conductive layer is prepared by rotating magnetron sputtering.

[0015] Thirdly, an acoustic wave receiving transducer is provided, comprising the aforementioned type 1-3 lead niobate piezoelectric composite material.

[0016] Preferably, the acoustic wave receiving transducer is an acoustic logging receiving transducer with an operating temperature of up to 350°C.

[0017] Compared with the prior art, the advantages of the present invention are: (1) Solved the problem of performance stability at ultra-high temperature: This invention abandons the traditional PZT-based materials and existing high-temperature ceramic systems, and instead uses lead metaniobate (PN) ceramic with extremely high Curie temperature as the piezoelectric phase, which ensures the ability of the composite material to withstand high temperatures above 350℃ from the material source, completely breaking through the upper limit of the service temperature of PZT-based materials of about 200℃, and is also better than the service temperature of high-temperature composite materials of about 300℃ in the prior art.

[0018] (2) Overcoming the performance application bias based on PN ceramics: By combining PN ceramics with specific structural parameters (λ / T=0.1-0.6, preferably 0.5-0.6), this invention successfully achieves lower performance of pure PN ceramics. k tThe λ / T value (approximately 0.25) is increased to over 0.35 in the composite material (an improvement of over 40%), enabling it to maintain good receiving sensitivity even at ultra-high temperatures. Notably, this optimal λ / T range differs significantly from conventional design experience (λ / T is typically 0.29-0.4) based on high-performance ceramics such as PZT, PMN-PZT, or BS-PT. This indicates that, considering the unique material properties of PN ceramics (such as high acoustic impedance and low mechanical quality factor), this invention, through specific structural design, achieves electromechanical coupling performance applicable to high-performance receiving transducers in composite materials, providing an effective approach to solving ultra-high temperature reception problems using PN ceramics.

[0019] (3) Achieving a good balance between high sensitivity and wide bandwidth: The introduction of the polymer phase in the composite material not only reduces acoustic impedance and improves matching, but also works synergistically with the structurally optimized PN ceramic pillar, enabling the transducer to achieve high receiving sensitivity (high bandwidth). k t While achieving high sensitivity, it also possesses a wider frequency response, overcoming the contradiction between high sensitivity and wide bandwidth in receiving transducers.

[0020] (4) The process is controllable and suitable for industrialization: The preparation method is based on mature cutting-filling technology. The core structural parameter λ / T can be precisely controlled by controlling the conventional cutting parameters. The process is simple, stable and has good repeatability, which lays the foundation for large-size, mass production of high-performance 1-3 type PN piezoelectric composite materials and has significant industrialization advantages. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a model diagram of the PN-based type 1-3 high-temperature piezoelectric ceramic composite material prepared in Example 1 of the present invention; Figure 2 These are physical images of the PN and PN-based type 1-3 piezoelectric ceramic composite materials prepared in Example 1 of this invention; Figure 3 These are the resonant frequency and anti-resonant frequency of the PN material prepared in Example 1 of this invention; Figure 4 These are the resonant frequency and anti-resonant frequency of the PN-based 1-3 piezoelectric ceramic composite material prepared in Example 1 of this invention. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to specific embodiments: The core of this invention lies in optimizing the vibration modes of lead metaniobate (PN) ceramics in the thickness direction by designing and controlling specific structural parameters in type 1-3 composite materials—specifically, the ratio λ / T of the transverse periodic dimension λ of the ceramic column to the thickness T of the composite material—within the range of 0.1-0.6 (preferably 0.5-0.6). Crucially, this λ / T range is not a simple transplantation of design experience from traditional high-performance piezoelectric ceramics (such as PZT), but rather a "specific" optimization range determined after extensive experimental verification based on the unique intrinsic properties of PN ceramics, such as their tungsten bronze structure, low sound velocity, and low mechanical quality factor. This structure effectively suppresses transverse parasitic vibrations and purifies thickness vibrations, thereby significantly improving the effective thickness electromechanical coupling coefficient of the composite material without significantly sacrificing its ultra-high temperature stability. k t This allows it to meet the sensitivity requirements of high-temperature receiving transducers.

[0023] Example 1

[0024] A type 1-3 lead metaniobate piezoelectric composite material for high-temperature acoustic logging receiver transducers, the specific preparation method includes the following steps: (1) Preparation of PN piezoelectric ceramic bulk Lead metaniobate ceramics with a tungsten bronze structure were prepared using a traditional solid-state reaction method. High-purity Pb3O4 and Nb2O5 were used as the main raw materials, with trace amounts of La2O3 and MnO2 added for doping modification to improve piezoelectric properties and insulation resistance. La2O3 doping helps stabilize the tungsten bronze structure and optimize dielectric properties, while the introduction of MnO2 increases the resistivity of the material and reduces dielectric loss at high temperatures, which is crucial for its high-temperature applications. The raw materials were ball-milled, dried, and sieved, then pre-fired at 850℃ to synthesize the PN phase. The synthesized powder was further ball-milled for refinement, granulated with a binder, and then dry-pressed into a green body at approximately 100 MPa. The green body was sintered in a sealed alumina crucible at 1250℃ for 4 hours to obtain a dense PN ceramic block. This block was then cut, ground, coated with silver electrodes, and polarized in a silicone oil bath at 220℃ with a 3 kV / mm DC electric field for 30 minutes. Tests showed that the PN ceramic block exhibited high ε... r piezoelectric constant d 33 Approximately 102 pC / N, thickness electromechanical coupling coefficient k t It is approximately 0.25, the relative permittivity is approximately 345, and the Curie temperature Tc > 560℃.

[0025] (2) Preparation of type 1-3 composite materials S2. Fix the polarized PN ceramic block (approximately 20mm x 20mm x 3mm) onto a precision cutting machine (dicing machine). Use a 0.18mm thick diamond blade to make the first cut along the first direction (set as the X direction), with a kerf depth of 2.5mm (leaving a 0.3mm allowance), a cutting speed of 1.5mm / min, and a center-to-center distance between adjacent kerfs of 0.72mm (i.e., the ceramic column design width a = 0.54mm, kerf b = 0.18mm). After cutting, a series of parallel ceramic strips are formed, with a ceramic substrate of approximately 0.5mm at the bottom.

[0026] S3. Rotate the workpiece 90° and make a second cut along the second direction (Y direction) perpendicular to the first direction. The cutting depth is also 2.5mm, the blade thickness and cutting speed remain unchanged, and the center-to-center distance of the kerf is also 0.72mm. After cutting, an array of PN ceramic pillars with a square cross-section of 0.54mm x 0.54mm is obtained. The transverse periodic dimension of this array is λ = a + b = 0.72mm. Place the array in an ultrasonic cleaner and clean it with ethanol for 10 minutes, then dry it.

[0027] S4. This embodiment is intended for use in high-temperature environments; therefore, a high-temperature epoxy resin with a glass transition temperature (Tg) > 250℃ is selected. The epoxy resin main agent and curing agent are mixed in proportion, stirred evenly, and then heated in an 80℃ oven for 20 minutes to reduce viscosity. Simultaneously, the clean and dry ceramic column array mold is preheated to 80℃. The preheated epoxy resin colloid is slowly injected into the gaps of the ceramic column array in the mold, ensuring complete filling. The entire mold is transferred to a vacuum drying oven and maintained under a vacuum of -0.095MPa for 15 minutes to remove air bubbles. Step curing is then performed: first, curing at 100℃ for 1 hour, then increasing to 150℃ for 1 hour, and finally curing at 220℃ for 1 hour. After completion, the power is turned off and the oven is cooled.

[0028] S5. Remove the cured preform from the mold and precision grind its upper and lower surfaces using a surface grinder. Continue grinding while cooling until all excess epoxy resin layer and the reserved 0.5mm ceramic substrate are completely removed, clearly exposing the end faces of all ceramic pillars. Finally, grind the composite material to the target thickness T=2.2mm. At this point, the core structural parameter λ / T=0.72 / 2.2≈0.327.

[0029] S6. The polished composite material was ultrasonically cleaned with ethanol and dried. Then it was placed in a rotary magnetron sputtering coating machine, and a chromium adhesion layer with a thickness of about 20 nm and a gold electrode layer with a thickness of 200 nm were sputtered sequentially on its upper and lower surfaces to obtain the final type 1-3 lead niobate piezoelectric composite material sample.

[0030] Performance testing The resonant frequency (fr) and anti-resonant frequency (fa) of the sample at room temperature were measured using a precision impedance analyzer. Typical spectra are shown below. Figure 3 , Figure 4 As shown, and according to the formula:

[0031] Calculate the electromechanical coupling coefficient of thickness k t Quasi-static approach adopted d 33 Measuring instrument (ZJ-3A type) for measuring piezoelectric constant d 33 The relative permittivity ε was measured at 1 kHz using a precision LCR meter. r The dielectric loss tanδ was calculated. The sample was placed in a high-temperature test fixture, and during the temperature rise from room temperature to 350°C (in 25°C steps), the impedance spectrum was measured after holding at each temperature for 10 minutes, and the dielectric loss tanδ at the corresponding temperature was calculated. k t The values ​​were used to evaluate temperature stability, and the test results are shown in the table below.

[0032] Table 1: Performance test results of lead niobate of the same size and its piezoelectric composite materials of types 1-3 prepared using it as a piezoelectric matrix.

[0033] Based on the table above Figure 3 and Figure 4 The impedance spectrum comparison results show that the type 1-3 PN composite materials prepared in Example 1, at room temperature, k t The value was improved by 44% compared to pure PN ceramics, reaching a maximum of 0.35. For example... Figure 3 As shown, the resonance peak of pure PN ceramics is relatively broad and gentle, indicating that there is some coupling between its vibration modes; as Figure 4 As shown, the impedance peaks of the type 1-3 PN composite materials prepared in this invention become steeper and more symmetrical. Despite its d 33 and ε r The sensitivity decreased due to polymer dilution, but the key receiver sensitivity index remained unchanged. k t The performance was significantly enhanced. This indicates that by controlling λ / T within a specific range (0.327 in this example), the composite material's structure effectively optimized the vibration modes, thereby improving the electromechanical coupling efficiency in the thickness direction. More importantly, the composite material can still maintain a performance of over 0.33 even at a high temperature of 350°C. k t The value demonstrates excellent temperature stability.

[0034] This performance improvement and stability can be attributed to the dual role of materials and structure. At the materials level, the extremely high intrinsic Curie temperature of PN ceramics (above 560℃) provides fundamental thermal stability for the entire composite system, maintaining its polarization state even at 350℃. At the structural level, the specific design with λ / T≈0.327 allows the polymer phase to not only connect, support, and reduce acoustic impedance, but more importantly, it mechanically couples and constrains the PN ceramic pillars, optimizing strain distribution and reducing performance degradation caused by thermal mismatch or increased internal friction at high temperatures. Therefore, the composite material of this invention exhibits excellent performance at 350℃. k t The retention rate of values ​​(e.g., the retention rate relative to room temperature values) is significantly better than that of conventional composites that rely on piezoelectric phases with low Curie temperatures.

[0035] Example 2 The main difference between this embodiment and Embodiment 1 is that the cutting parameters are adjusted to explore the influence of the λ / T ratio and to prepare a transducer material suitable for underwater acoustic receivers in ambient temperature waters.

[0036] (1) The preparation of PN ceramic bulk material is the same as in Example 1.

[0037] (2) Preparation of type 1-3 composite materials S2-S3. Use PN ceramic blocks of the same size. Select blade thickness of 0.10mm. The center-to-center spacing of the first cut (X direction) is set to 0.64mm (design a=0.54mm, b=0.10mm). The parameters are the same for the second cut (Y direction). A ceramic column array with λ=0.64mm is obtained.

[0038] S4. Select a conventional room temperature curing epoxy resin (Tg approximately 120℃). After degassing the mixed epoxy resin colloid under vacuum, directly inject it into the gaps of the ceramic column array. Allow it to stand at room temperature for 24 hours for initial curing, and then cure it at 80℃ for 2 hours.

[0039] S5. Grind to the final thickness T=1.28mm. At this point, λ / T=0.64 / 1.28=0.50, which falls within the preferred range.

[0040] S6. Electrode preparation is the same as in Example 1.

[0041] Performance testing The composite material sample was tested at room temperature. d 33 Approximately 88 pC / N, k t Up to 0.38, ε rThe value is approximately 210, and the tanδ is 0.06. This example demonstrates that when λ / T is controlled at a preferred value of 0.5, the composite material achieves a higher [value] than in Example 1 (λ / T = 0.327). k t The value indicates superior thickness vibration performance.

[0042] Comparative Example 1 Following the steps of Example 1, but changing the spacing of the second cut (Y direction). The blade thickness is set to 0.18 mm, and the center-to-center spacing of the Y-direction cuts is set to 1.44 mm (designed ceramic column width a = 1.26 mm, cut width b = 0.18 mm), then the transverse period λ = 1.44 mm. The final grinding thickness T remains 2.2 mm, at which point λ / T ≈ 0.655. The resulting composite material has a room temperature... k t The value is approximately 0.31.

[0043] To investigate the influence of the core structural parameter λ / T, this comparative example is compared with Examples 1 and 2. All three use the same PN ceramic and resin system, differing only in λ / T. Specific parameters and performance comparisons are shown in the table below.

[0044] Table 2: Comparison of properties of PN-based composite materials with different λ / T

[0045] Based on the data in the table above and the experimental results, the following conclusions can be drawn: 1. λ / T has an optimal range: When λ / T is 0.50 (Example 2), the composite material achieves the highest [value / value]. k t Value (0.38); when λ / T deviates from this value, whether it increases (Comparative Example 1, 0.655) or decreases (Example 1, 0.327). k t The values ​​all decreased. This demonstrates the necessity of controlling λ / T within the range of 0.1-0.6, preferably 0.5-0.6.

[0046] 2. Specificity of Parameter Selection: It is worth noting that for PN ceramics, the optimal λ / T value (approximately 0.5) is significantly higher than the optimization experience commonly used in the field for perovskite-structured ceramics based on PZT or BS-PT structures (typically, high performance is achieved by controlling T / λ between 2.5 and 3.5, i.e., λ / T approximately 0.29 to 0.36). If this conventional experience is directly applied, results such as in Example 1 (λ / T = 0.327) will be obtained, which, although the performance has been improved, is not optimal.

[0047] 3. Possible Mechanism: This phenomenon may be related to the unique tungsten bronze structure, lower sound velocity, and mechanical quality factor of PN ceramics. For PN materials, a larger λ / T (i.e., a relatively "shorter" ceramic column geometry) may be more conducive to matching its intrinsic vibrational characteristics, suppressing harmful modes, and thus more effectively purifying and enhancing thickness vibrations, achieving... k t Maximize the value.

[0048] This further explains why directly applying conventional structural optimization experience based on ceramics such as PZT or BS-PT (pursuing smaller λ / T or larger T / λ) cannot achieve optimal performance in PN composites. For these conventional high-performance ceramics, their higher acoustic velocities and electromechanical coupling coefficients make it easier for slender ceramic pillars (smaller λ / T) to excite efficient thickness vibrations. However, for PN ceramics, their lower acoustic velocities and different vibration mode coupling characteristics mean that a more balanced or thicker pillar geometry (larger λ / T) is needed to achieve optimal concentration and conversion of vibrational energy.

[0049] Based on the above experimental data, in Example 2, the composite material achieved the highest performance when λ / T was 0.50. k t The value is (0.38). In Comparative Example 1, if λ / T deviates from this value and increases to 0.655, the performance degrades.

[0050] These experimental phenomena suggest that for PN ceramics, which possess a unique tungsten bronze structure, low sound velocity, and low mechanical quality factor, the structural parameters (λ / T approximately 0.5) required to achieve optimal performance in one-dimensional ceramic pillar arrays differ from the common optimization range (λ / T approximately 0.29-0.36) for conventional perovskite piezoelectric ceramics (such as PZT and BS-PT). Setting λ / T within this range may be more conducive to matching the specific vibrational characteristics of PN ceramics, thereby more effectively improving the electromechanical conversion efficiency in the thickness direction. Therefore, for PN ceramics, the optimal λ / T range (0.5-0.6) was determined, and [the desired performance was achieved]. k t The value is significantly improved from 0.25 to over 0.38 for pure ceramics.

[0051] Comparative Example 2 Following the approach outlined in the embodiment of publicly available document CN117560986A, this study attempted to use PZT-5H ceramic (Tc approximately 350°C) as the piezoelectric phase and prepared type 1-3 composite materials by controlling T / λ≈3.0 (i.e., λ / T≈0.33) according to its teachings. The PZT composite material was tested at room temperature. k t It can reach 0.65, d 33Approximately 450 pC / N, indicating excellent performance. However, after placing it in a 250°C environment for 1 hour and then testing, [the following occurred]. k t The dielectric value drops to less than 0.40, and the dielectric loss increases sharply; the performance degrades severely at 300℃, making stable operation impossible. This confirms the limitations of PZT-based materials in ultra-high temperature environments.

[0052] Comparative Example 3 Referring to the bismuth cobalt niobate-lead titanate (BS-PT) based high-temperature ceramics described in public document CN117560987A, type 1-3 composite materials were prepared according to the method therein, controlling T / λ≈3.2. This material can maintain [its properties] at 300℃. k t Approximately 0.55, exhibiting good high-temperature performance. However, when attempting to increase its operating temperature to 350℃ and maintain it at that temperature for an extended period, its... k t The value gradually decreased to around 0.45, and the polymer phase (even when using high-temperature epoxy resin) showed slight signs of deterioration, posing a challenge to performance stability.

[0053] In summary, as shown in Comparative Examples 2 and 3, neither the high-performance PZT material nor the BS-PT material specifically designed for high temperatures can meet the long-term operating requirements of 350℃ and above in terms of temperature resistance or high-temperature stability. Furthermore, Comparative Example 1 and the series of comparative analyses indicate that simply using PN ceramics without specifically optimizing the composite material structure (i.e., controlling λ / T within 0.5-0.6) cannot fully realize its performance potential. Only by combining "PN ceramics with high Curie temperature" with "tailor-made λ / T structural parameters," as shown in Examples 1 and 2, can a synergistic enhancement effect be achieved.

[0054] As can be seen from the comprehensive embodiments and comparative examples, the type 1-3 composite material provided by the present invention, which uses PN ceramic as the piezoelectric phase and controls λ / T at 0.1-0.6 (preferably 0.5-0.6), uniquely balances ultra-high temperature stability (≥350℃) and good receiving sensitivity. k t The two performance indicators (≥0.35) that are difficult to achieve simultaneously in existing technologies provide a new and superior material solution for ultra-high temperature acoustic wave receiving applications.

[0055] Comparative Example 4 This comparative example is a direct high-temperature performance comparison with the closest prior art embodiment (CN117560987A). Following the method disclosed in Example 1 of prior art document CN117560987A, using the bismuth cobalt niobate-lead titanate (BS-PT) based high-temperature ceramic as the piezoelectric phase, and controlling T / λ≈3.2 (i.e., λ / T≈0.31), type 1-3 composite materials were prepared. Simultaneously, a PN-based composite material was prepared using the method of Example 2 of this invention (λ / T=0.50). Both composite materials were fabricated into transducer units of the same specifications and placed in a programmable high-temperature furnace for high-temperature aging and performance stability testing: the temperature was raised from room temperature to 350°C and held continuously at 350°C for 100 hours, with cooling to room temperature every 24 hours to measure the performance. k t value.

[0056] Test results: BS-PT based composite material (Comparative Example 4): Initial room temperature k t The value is approximately 0.60, and it decreases with high-temperature aging. k t The value decreased significantly after being kept at 350℃ for 24 hours. k t The value dropped to 0.52; after 100 hours of heat preservation, the kt value further decreased to around 0.45, and the dielectric loss increased significantly. Its polymer phase (high-temperature epoxy resin) showed slight yellowing and embrittlement signs under long-term 350℃ conditions.

[0057] PN-based composite material (Example 2 of the present invention): initial room temperature k t The value is 0.38. During the entire aging process at 350℃, its... k t The value remained exceptionally stable, consistently fluctuating between 0.36 and 0.38, with a decay rate of less than 5%. The composite material exhibited intact appearance and structure, with no visible degradation.

[0058] The comparative experimental results above show that the PN-based composite material provided by this invention exhibits significantly better long-term performance stability than the BS-PT-based composite material in an ultra-high temperature environment of 350℃. Although its room temperature kt value is relatively low, its performance degradation is minimal at extreme high temperatures, enabling it to operate stably for a long time. This verifies that the technical solution of "combining PN ceramics with a specific λ / T structure" adopted in this invention has unique technical advantages in solving the material stability problem of ultra-high temperature acoustic wave receiving transducers at 350℃ and above.

[0059] Application Examples The type 1-3 lead niobate piezoelectric composite material (λ / T=0.50) prepared in Example 2 was processed into a disc with a diameter of 15 mm and a thickness of 2.2 mm. After welding leads, it was encapsulated in a high-temperature and pressure-resistant metal shell to form an acoustic logging receiver transducer unit. This transducer unit was integrated into the receiver array of an acoustic logging instrument. Continuous performance testing for up to 500 hours was conducted in an experimental setup simulating a downhole high-temperature environment of 350°C and a high-pressure environment of 140 MPa.

[0060] Test Results: During a 500-hour test, the transducer unit exhibited a flat receiving frequency response, with the receiving voltage sensitivity fluctuation at its center frequency less than ±1.5 dB. In contrast, the comparative transducer made using the BS-PT-based material of Comparative Example 4 showed a sensitivity decrease of over 3 dB after only 100 hours of testing. Therefore, the transducer based on the composite material of this invention demonstrates excellent long-term operational stability in simulated ultra-high temperature and high pressure downhole environments, making it suitable for ultra-deep well acoustic logging.

[0061] The success of this application example directly verifies the core advantage of the composite material of the present invention: that is, it maintains sufficiently high receiving sensitivity (due to high and stable) even under extreme high temperature (350°C) and high pressure environments. k t The transducer boasts high frequency response and long-term operational reliability. This is thanks to the inherent ultra-high temperature stability of the PN ceramic phase, as well as the optimization of vibration modes and mechanical integrity by the λ / T=0.50 structure, enabling the transducer to maintain a flat frequency response and stable signal reception quality even in harsh environments.

[0062] The above embodiments are merely illustrative of the technical concept and features of the present invention, intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be construed as limiting the scope of protection of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and thus all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention.

Claims

1. A type 1-3 lead metaniobate piezoelectric composite material, characterized in that, It includes a one-dimensionally connected lead niobate piezoelectric ceramic phase and a three-dimensionally connected polymer phase. The lead niobate piezoelectric ceramic phase is an array of lead niobate ceramic pillars with a tungsten bronze structure. The lead niobate piezoelectric ceramic phase has a Curie temperature higher than 557°C. The ratio λ / T of the transverse periodic dimension λ of the ceramic pillars to the thickness T of the composite material is 0.1-0.

6.

2. The type 1-3 lead metaniobate piezoelectric composite material according to claim 1, characterized in that, The λ / T is 0.5-0.

6.

3. The type 1-3 lead metaniobate piezoelectric composite material according to claim 1 or 2, characterized in that, The volume fraction of the lead niobate piezoelectric ceramic phase is 10-90%.

4. The type 1-3 lead metaniobate piezoelectric composite material according to claim 1 or 2, characterized in that, The polymer phase is epoxy resin.

5. A method for preparing a type 1-3 lead niobate piezoelectric composite material as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Provides lead metaniobate piezoelectric ceramic bulk materials; S2. The ceramic block is cut in the first direction to form a parallel first slit; S3. A second cut is made along a second direction perpendicular to the first direction to form an independent array of lead niobate ceramic pillars; wherein, the cutting parameters are controlled so that the ratio λ / T of the sum of the ceramic pillar width a and the kerf width b to the target thickness T is 0.1-0.6; S4. Fill the gaps in the ceramic column array with a polymer precursor and cure it to form a polymer phase; S5. Grind the blank obtained in step S4, remove excess material from the surface until the target thickness T is reached, and expose the end face of the ceramic column; S6. Prepare a conductive layer on the surface of the polished blank to obtain the composite material.

6. The preparation method of the type 1-3 lead niobate piezoelectric composite material according to claim 5, characterized in that, In step S3, λ / T is 0.5-0.

6.

7. The preparation method of the type 1-3 lead niobate piezoelectric composite material according to claim 5, characterized in that, In step S4, the polymer precursor is an epoxy resin colloid; when used in an environment above 200°C, a high-temperature epoxy resin colloid is used and preheated before potting.

8. The method for preparing type 1-3 lead niobate piezoelectric composite material according to claim 5, characterized in that, In step S6, the conductive layer is prepared by rotating magnetron sputtering.

9. A sound wave receiving transducer, characterized in that, It includes type 1-3 lead niobate piezoelectric composite materials as described in any one of claims 1-4.

10. The acoustic wave receiving transducer according to claim 9, characterized in that, The acoustic wave receiving transducer is an acoustic logging receiving transducer with an operating temperature of up to 350℃.

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