Piezoelectric sensing integrated ceramic core shell and preparation and monitoring method thereof

Abstract

The invention provides an integrated ceramic core shell integrated with piezoelectric sensing and a preparation and monitoring method thereof, and relates to the technical field of ceramic core preparation. The ceramic core shell comprises a ceramic base body formed through an additive manufacturing process, a piezoelectric sensing unit arranged in a monitoring area, a protective shell wrapping and sealing the sensing unit and a signal transmission line embedded in the protective shell. The preparation method comprises the following steps: determining a monitoring area based on thermal-mechanical coupling simulation and constructing a three-dimensional digital model; sequentially printing a ceramic substrate, a piezoelectric sensing unit, a polarized electrode of the piezoelectric sensing unit, a synchronously formed protective shell and a signal transmission line through a multi-material additive manufacturing process; and carrying out integrated sintering and polarization treatment on the green body. Integrated manufacturing and integration of the sensor and a ceramic structure are achieved, and the problem that a traditional external sensor cannot conduct reliable monitoring in a high-temperature and complex-structure casting mold core is solved.

Description

Technical Field

[0001] This invention relates to the field of ceramic core preparation technology, specifically to an integrated ceramic core shell with integrated piezoelectric sensing and its preparation and monitoring methods. Background Technology

[0002] In cutting-edge fields such as aerospace, energy and power, and high-end equipment manufacturing, the performance of complex high-temperature alloy castings directly determines the efficiency and reliability of core equipment. The production of such castings generally employs investment casting, the core of which lies in using ceramic cores and shells with specific high-temperature mechanical properties and thermochemical stability to form the complex internal cavities and external shapes of the castings.

[0003] During the casting process, ceramic cores and shells must withstand thermal shocks from molten metal at temperatures far exceeding their normal service temperatures, and remain in a high-temperature thermal gradient environment for extended periods. Under these extreme conditions, ceramic materials are highly susceptible to unpredictable and non-uniform thermal deformation due to the coupled effects of multiple physicochemical effects, including mismatched coefficients of thermal expansion, sintering shrinkage, phase transformation, and gravitational creep. This phenomenon has become a key bottleneck restricting the yield and performance improvement of high-end castings. Specifically, the thermal deformation of the core / shell is directly transmitted to the solidifying casting, leading to uncontrollable deviations in its critical dimensions. In severe cases, it can even cause internal defects such as shrinkage porosity and thermal cracking, resulting in substandard mechanical properties of the casting and ultimately causing high scrap costs and resource waste.

[0004] To quantify and control this process, accurate monitoring of the thermal deformation behavior of ceramic cores / shells at high temperatures is crucial. However, existing mainstream monitoring technologies have fundamental limitations. One is strain gauge measurement: this method suffers from rapid performance degradation at high temperatures, and the complex bonding process and lead wire difficulties make it difficult to achieve reliable and consistent measurements on complex curved surfaces. Another is contact displacement sensor method: its response speed is slow, it cannot capture the dynamic deformation process, and the presence of a physical probe severely restricts its installation location, making it difficult to achieve full-area monitoring.

[0005] Existing patent CN120533058A discloses a method and system for controlling the temperature field of alloy die casting to reduce hot cracking. Its core is to optimize the solidification process of castings by externally regulating the temperature field of the mold. Its focus is on the prevention of hot cracking of the alloy itself, which belongs to the control and optimization of process parameters. It does not involve the direct measurement of the deformation of the ceramic core / shell body at high temperature.

[0006] Existing patent CN114923917A discloses an integrated method for the correction and inspection of ceramic cores. Its core lies in the correction and geometric dimension inspection of ceramic cores at room temperature or lower temperature after sintering. Its technical focus is on the "post-" correction and contour measurement of the finished product. It cannot be applied to the high-temperature environment of casting to achieve real-time perception of the dynamic process of thermal deformation of cores / shells.

[0007] In summary, none of the existing patents mentioned above have solved the fundamental problem of in-situ, real-time, and accurate monitoring of thermal deformation of ceramic cores / shells under high-temperature casting conditions. Summary of the Invention

[0008] Based on the aforementioned problems in existing technologies, this invention proposes an integrated ceramic core and shell with integrated piezoelectric sensing, as well as its preparation and monitoring methods. By simultaneously molding the piezoelectric sensing unit and the ceramic core and shell using an integrated additive manufacturing process, an internal monitoring system with structural symbiosis is formed, thereby solving the problem that traditional external sensors cannot achieve in-situ, real-time, and accurate monitoring of complex ceramic core and shell structures under high-temperature environments.

[0009] To achieve the above objectives, the first aspect of this application proposes an integrated ceramic core and shell for integrating piezoelectric sensing, the specific technical solution of which is as follows: An integrated ceramic core and shell for integrating piezoelectric sensing, comprising: Ceramic matrix formed by additive manufacturing process; At least one piezoelectric sensing unit is embedded in the monitoring area of ​​the ceramic substrate by an additive manufacturing process. The piezoelectric sensing unit includes a piezoelectric ceramic layer and a polarized electrode layer formed on its surface. The protective shell is formed and sealed to the piezoelectric sensing unit using an additive manufacturing process. The signal transmission line is formed synchronously with the protective shell through additive manufacturing process and is embedded in the protective shell. One end of the signal transmission line is connected to the polarized electrode layer, and the other end extends to the outer surface of the ceramic core shell.

[0010] Furthermore, the monitoring area is determined based on the thermo-mechanical coupling simulation analysis of the ceramic core and shell during the hot processing. The monitoring area is the region in the simulation results where the mean stress value exceeds a preset stress threshold or the total deformation exceeds a preset deformation threshold.

[0011] Furthermore, a fitting gap is formed between the protective shell and the ceramic substrate to compensate for sintering shrinkage, and the value of the fitting gap ranges from 30 to 70 μm.

[0012] To achieve the above objectives, the second aspect of this application proposes a method for fabricating an integrated ceramic core and shell with integrated piezoelectric sensing, the specific technical solution of which is as follows: A method for fabricating an integrated ceramic core and shell for integrating piezoelectric sensing, comprising the following steps: S1. Based on thermo-mechanical coupling simulation analysis, the monitoring area of ​​the ceramic matrix is ​​determined, and a three-dimensional digital model of the ceramic core and shell is constructed. S2. Based on the aforementioned three-dimensional digital model, an additive manufacturing process is used to print and form a ceramic substrate; S3. Using additive manufacturing process, the piezoelectric sensing unit and its polarization electrode are printed in the monitoring area of ​​the ceramic substrate. S4. Using multi-material additive manufacturing process, print the protective shell covering the piezoelectric sensing unit and simultaneously print the signal transmission line. S5. Sinter the printed green blank; S6. The piezoelectric sensing unit is polarized through the signal transmission line.

[0013] Furthermore, in step S1, the construction of the three-dimensional digital model of the ceramic core and shell includes constructing a three-dimensional digital model of the ceramic substrate integrating the piezoelectric sensing unit, the protective shell, and the signal transmission line; wherein, a mounting groove is generated in the monitoring area of ​​the ceramic substrate, the inner cavity shape of the mounting groove is complementary to the outer shape of the protective shell; and the layout path of the signal transmission line is planned.

[0014] Furthermore, in step S2, photopolymerization 3D printing is used to print a ceramic substrate with mounting grooves by controlling the printing layer thickness and exposure energy; wherein, the solid content of the silica-based ceramic slurry used is 75-86wt%, and the particle size of the ceramic powder is 1-20µm; the layer thickness of the photopolymerization 3D printing is 40-80µm, and the single-layer exposure energy is 40-70mW.

[0015] Furthermore, in step S3, the piezoelectric sensing unit is printed using microdroplet jetting technology, filling the mounting groove with a piezoelectric ceramic slurry with a solid content of 75-86wt%, and the printing temperature is 80℃-120℃.

[0016] Furthermore, in step S5, the sintering process includes: heating to 500-650°C in an air atmosphere and holding at that temperature to complete degreasing, followed by heating to 1100-1350°C in an argon protective atmosphere and sintering and holding at that temperature.

[0017] Furthermore, in step S6, the polarization treatment includes: applying a DC electric field of 1-5 kV / mm at a temperature of 150-220°C in a polarizing liquid environment for 10-50 minutes.

[0018] To achieve the above objectives, the third aspect of this application proposes a monitoring method for an integrated ceramic core and shell with integrated piezoelectric sensing, the specific technical solution of which is as follows: A monitoring method for an integrated ceramic core and shell with integrated piezoelectric sensing, used to monitor the aforementioned integrated ceramic core and shell with integrated piezoelectric sensing, includes the following steps: Through experimental calibration, a model was established to establish the correspondence between the resonant frequency shift of the piezoelectric sensing unit and the thermal deformation of the ceramic core and shell. During the hot working process, the resonant frequency data of the piezoelectric sensing unit is collected in real time; Based on the established correspondence model, the collected resonant frequency data is converted into thermal deformation and the monitoring results are output. When the thermal deformation exceeds the preset threshold, an early warning is triggered.

[0019] By applying the above-described technical solution of the present invention, at least the following technical effects are achieved: 1. This invention utilizes an integrated additive manufacturing process to simultaneously print the piezoelectric sensing unit inside the ceramic core and shell during the manufacturing process, forming a fusion interface at the microscopic level. This fundamentally eliminates the problems of detachment and signal drift caused by adhesive failure at high temperatures or thermal expansion mismatch in traditional "post-installed" sensors, laying a solid foundation for long-term, stable, and reliable monitoring in extreme high-temperature environments above 600℃.

[0020] 2. This invention precisely molds the piezoelectric sensing unit into key parts such as complex internal cavities that are inaccessible by traditional methods, enabling full-area, in-situ monitoring of stress and deformation states of complex structural components, thus solving the long-standing problem of monitoring blind spots.

[0021] 3. This invention uses thermo-mechanical coupling simulation to determine key monitoring areas, achieving coordinated optimization of structural design and sensor layout. By controlling printing parameters, it not only ensures macroscopic dimensional accuracy but also directly shapes the microstructure and performance of the piezoelectric sensing unit, thereby guaranteeing that each product has highly consistent sensing accuracy and response speed.

[0022] 4. This invention combines the complex processes of "structural manufacturing" and "functional integration" into "one-time molding," significantly simplifying the process and shortening the cycle time. Simultaneously, the real-time and accurate monitoring data it provides can be directly used to guide process parameter optimization, forming a closed-loop control system. This significantly improves the dimensional qualification rate of high-end castings, reduces the scrap rate, and achieves cost reduction and efficiency improvement.

[0023] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0024] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic flowchart of the preparation method of the integrated ceramic core and shell with integrated piezoelectric sensing proposed in this invention is shown. Figure 2 A flowchart illustrating the monitoring method for an integrated ceramic core and shell with integrated piezoelectric sensing proposed in this invention is presented. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] The present invention will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed by the present invention.

[0027] According to a first aspect of the present invention, an integrated ceramic core and shell with integrated piezoelectric sensing is provided for the fabrication of turbine blades for aero-engines. The integrated ceramic core and shell includes a ceramic substrate, a piezoelectric sensing unit, a protective shell, and signal transmission lines. A mounting groove is designed in the monitoring area where thermal deformation of the ceramic substrate is most significant. The piezoelectric sensing unit is embedded and fixed within the mounting groove of the ceramic substrate using an additive manufacturing process. The protective shell is formed using an additive manufacturing process to completely enclose and seal the piezoelectric sensing unit. The signal transmission lines are formed simultaneously with the protective shell using an additive manufacturing process and are embedded within the ceramic substrate and the protective shell. One end of the signal transmission lines is connected to the electrode of the piezoelectric sensing unit, and the other end forms a connection end exposed on the outer surface of the ceramic core and shell.

[0028] Specifically, both the ceramic substrate and the protective shell are made of silica-based ceramic. The thermal deformation monitoring area of ​​the ceramic substrate is the region where the equivalent stress value exceeds the stress threshold, or the region where the total deformation exceeds the size threshold. Mounting slots are arranged in the monitoring area to ensure that the piezoelectric sensing unit can effectively capture the most representative thermal deformation information. The shape of the protective shell and the inner cavity shape of the mounting slot are designed as complementary structures that fit each other. The mounting slot is a negative-shaped cavity formed by the ceramic substrate material, while the protective shell is a positive-shaped solid filling this cavity, forming a geometric conformal relationship in three-dimensional space. This design ensures that the protective shell can be accurately positioned and constrained within the mounting slot. Simultaneously, a fitting gap is provided between the protective shell and the ceramic substrate to compensate for dimensional changes in the material during subsequent sintering. Finally, through co-firing, a dense and strong sintered bond is formed at the interface. The protective shell protects the piezoelectric sensing unit from the impact of high-temperature molten metal and chemical corrosion.

[0029] Optionally, the stress threshold for the thermal deformation monitoring area of ​​the ceramic matrix is ​​50 MPa, and the total deformation size threshold is 0.1 mm.

[0030] Optionally, the fit gap between the protective shell and the ceramic substrate is 30-70μm.

[0031] Specifically, the piezoelectric sensing unit consists of a piezoelectric ceramic layer and a polarized electrode layer formed on its surface. The piezoelectric ceramic layer uses a piezoelectric ceramic material capable of long-term stable operation in high-temperature environments of 600°C and above, preferably a bismuth layered structure or a perovskite structure. The polarized electrode layer uses a high-temperature conductive material suitable for additive manufacturing to ensure the electrical stability and reliability of the electrode at high temperatures, preferably platinum, platinum alloys, or nickel.

[0032] Specifically, the signal transmission line also uses a high-temperature conductive material suitable for additive manufacturing. One end of the signal transmission line is connected to the polarization electrode of the piezoelectric sensing unit, and then extends along a preset path, finally forming a pad structure for external connection at a designated position on the outer surface of the ceramic core shell, thereby forming a continuous electrical connection path together with the protective shell and the piezoelectric sensing unit. Preferably, the signal transmission line is preset to be embedded inside the composite structure formed by the ceramic substrate and the protective shell, and its wiring path passes through the reinforcing rib area of ​​the ceramic substrate or a low-stress area determined by simulation.

[0033] When the integrated ceramic core and shell proposed in this invention deforms due to heat during the casting process, the deformation stress is transmitted to the piezoelectric sensing unit through the protective shell. The piezoelectric sensing unit converts the mechanical stress into an electrical signal based on the piezoelectric effect. The electrical signal is transmitted to an external data acquisition and processing system through a signal transmission line. By monitoring the shift of the resonance peak of the piezoelectric sensing unit, the real-time thermal deformation of the ceramic core and shell at high temperature can be calculated.

[0034] According to a second aspect of the present invention, a method for fabricating an integrated ceramic core and shell with integrated piezoelectric sensing is provided, see reference. Figure 1 As shown, the preparation method includes the following steps: S1. Based on thermo-mechanical coupling simulation analysis, the monitoring area of ​​the ceramic matrix is ​​determined, and a three-dimensional digital model of the ceramic core and shell is constructed. S2. Based on the aforementioned three-dimensional digital model, an additive manufacturing process is used to print and form a ceramic substrate; S3. Using additive manufacturing process, the piezoelectric sensing unit and its polarization electrode are printed in the monitoring area of ​​the ceramic substrate. S4. Using multi-material additive manufacturing process, print the protective shell covering the piezoelectric sensing unit and simultaneously print the signal transmission line. S5. Sinter the printed green blank; S6. The piezoelectric sensing unit is polarized through the signal transmission line.

[0035] The above step S1 specifically includes: S11. Determine the monitoring area of ​​the ceramic core and shell based on thermo-mechanical coupling simulation analysis; Specifically, a computer-aided engineering (CAE) thermo-mechanical coupling model is established based on the actual working conditions of the ceramic core and shell in the target hot working environment. The actual working conditions include the temperature field distribution, the hydrostatic pressure of the molten metal, and the constraints imposed by the solidification shrinkage of the casting. Through simulation calculations, stress distribution cloud maps and deformation cloud maps of the ceramic core and shell at high temperatures are obtained; areas where the equivalent stress value exceeds a preset threshold, or areas where the total deformation exceeds a preset threshold, are identified as monitoring areas for the thermal deformation of the ceramic core and shell.

[0036] In this embodiment, the preset threshold for equivalent stress is 50 MPa, and the preset threshold for total deformation is 0.1 mm.

[0037] S12. Construct a three-dimensional digital model that integrates multiple materials.

[0038] Specifically, using the multi-entity modeling function of computer-aided design (CAD) software, a three-dimensional digital model of a ceramic substrate integrated with a piezoelectric sensing unit, its protective shell, and signal transmission lines is constructed within the same design environment. A mounting groove is provided in the monitoring area of ​​the ceramic substrate, the inner shape of which complements the shape of the protective shell. The piezoelectric sensing unit is located within this mounting groove and encapsulated by the protective shell. The signal transmission lines are arranged within the composite structure of the ceramic substrate and the protective shell, with one end connected to the polarization electrode of the piezoelectric sensing unit and the other end extending to the outer surface of the ceramic core shell.

[0039] The mounting groove is constructed as follows: the cavity shape of the mounting groove is a complementary shape adapted to the shape of the protective shell. The fitting gap between the ceramic substrate and the protective shell is set based on the sintering shrinkage rate of the silica-based ceramic material to compensate for dimensional changes during sintering. In subsequent sintering, the two materials form a strong sintered bond through densification shrinkage. The signal transmission line extends along the reinforcing ribs of the ceramic substrate or is located in a low-stress region determined by CAE simulation; simultaneously, the ends of the signal transmission line are equipped with pad structures for external electrical connections.

[0040] In this embodiment, the low-stress region is defined as the area where the first principal stress value consistently remains below 50 MPa in the CAE simulation. A minimum spacing of 0.1 mm is maintained between the signal transmission line path and any outer surface of the ceramic core shell, as well as any inner surface of any cavity within the ceramic core shell. The pad structure is constructed of platinum paste integrally molded with the signal transmission line, with a thickness of at least 0.1 mm and a planar dimension of at least 1. 1mm 2 .

[0041] The above step S2 specifically includes: Specifically, the three-dimensional digital model constructed in step S1 is imported into an additive manufacturing equipment that can be used for multi-material molding; silica-based ceramic material is selected as the molding material, and the ceramic substrate is formed by printing layer by layer according to the model through additive manufacturing process; when the printing reaches the monitoring area, the mounting groove is formed according to the three-dimensional digital model. The pre-forming of the ceramic substrate and the built-in mounting groove is completed.

[0042] In this embodiment, the silica-based ceramic material is a photocurable ceramic slurry with a solid content of 75-86 wt% and a ceramic powder particle size of 1-20 µm; the photocurable 3D printing technology is used, with a printing layer thickness of 40-80 µm and a single-layer exposure energy of 40-70 mW.

[0043] After printing, the resulting green blank is degreased and heated to 500-650℃ in air at a heating rate of 0.5-2℃ / min, and held at that temperature for 1-10 hours.

[0044] The above step S3 specifically includes: Specifically, after printing the ceramic substrate and mounting groove, the integrated printing of the piezoelectric sensing unit is performed: the mounting groove is precisely positioned and calibrated using the printing equipment's visual positioning system; the material switching system is activated to switch the printing material from silica-based ceramic slurry to piezoelectric ceramic slurry, and the piezoelectric ceramic slurry is continuously deposited into the mounting groove using micro-droplet jetting technology, forming the piezoelectric sensing unit in situ. During this process, the residual heat of the ceramic substrate and the heat of the newly printed piezoelectric ceramic slurry are used to keep them in a semi-molten state at the contact interface and allow them to diffuse into each other, thus achieving a strong interfacial bond. Subsequently, the printing material is switched to a high-temperature conductive slurry to print polarized electrodes on the surface of the formed piezoelectric sensing unit.

[0045] In this embodiment, the selected piezoelectric ceramic slurry is a bismuth layered or perovskite structure piezoelectric ceramic material with a solid content of 75-86 wt% and a viscosity of 1000-2000 mPa·s. When printing the piezoelectric sensing unit, a micro-droplet jet printhead with a nozzle diameter of 0.1-0.8 mm is used; the printing temperature is 80-120℃. The conductive phase of the high-temperature conductive slurry is selected from platinum, platinum alloys, or nickel metal.

[0046] The above step S4 specifically includes: Specifically, after printing the piezoelectric sensing unit and polarization electrode, the packaging and wiring printing are initiated. The material switching system switches back to silica-based ceramic paste, and the high-temperature conductive paste printing system is started simultaneously.

[0047] Through multi-head collaborative operation and path planning, high-temperature conductive paste is printed onto a preset trajectory to form a signal transmission line while simultaneously printing the protective shell structure. This line starts at the polarization electrode and is subsequently enveloped by the deposited ceramic paste during printing, thus becoming completely embedded within the protective shell structure. Ultimately, its connection endpoints are exposed on the outer surface of the ceramic core shell. During printing, infrared irradiation is used to perform phased, localized curing of the deposited paste area to stabilize the line shape and ensure the interface quality between dissimilar materials.

[0048] In this embodiment, the printing material used for the protective shell is the same as that used for the ceramic substrate, and the printing material used for the signal transmission lines is the same as that used for the polarization electrodes.

[0049] The above step S5 specifically includes: Specifically, after printing all the above structures, the ceramic core and shell preforms are sintered as a single unit. This process ensures complete sintering of the ceramic substrate and protective shell, and guarantees a stable integration with the internal piezoelectric sensing unit and signal transmission lines. After sintering, impedance analysis and other methods are used to verify the electrical and resonant characteristics of the integrated piezoelectric sensing unit under high-temperature conditions, ensuring that it meets the monitoring requirements.

[0050] In this embodiment, the integrated sintering process is carried out in an atmosphere sintering furnace. First, degreasing and binder removal are performed: the temperature is raised from room temperature to 500-650°C at a rate of 0.5-2°C / min and held for 1-10 hours to completely remove various organic binders. Then, high-temperature co-firing is performed: under an argon protective atmosphere, the temperature is raised to a sintering temperature of 1100-1350°C at a rate of 1-6°C / min and held for 2-10 hours to completely densify the silica-based ceramic matrix and the protective shell, and to achieve a stable bond with the internal piezoelectric sensing unit and wires.

[0051] The above step S6 specifically includes: Specifically, after sintering, the piezoelectric sensing unit integrated inside the ceramic core and shell is polarized to activate its piezoelectric properties. A high-voltage DC electric field is applied to the built-in signal transmission lines and polarization electrodes through the pad structure exposed on the outer surface in step S4.

[0052] In this embodiment, the polarization treatment is carried out in a silicone oil bath, the polarization temperature is 150-220℃, the applied DC electric field strength is 1-5kV / mm, and the polarization time is 10-50min.

[0053] According to a third aspect of the present invention, a monitoring method for an integrated ceramic core and shell with integrated piezoelectric sensing is proposed, see reference. Figure 2 As shown, the monitoring method includes the following steps: Through experimental calibration, a model was established to establish the correspondence between the resonant frequency shift of the piezoelectric sensing unit and the thermal deformation of the ceramic core and shell. During the hot working process, the resonant frequency data of the piezoelectric sensing unit of the ceramic core and shell are collected in real time; Based on the established correspondence model, the collected resonant frequency data is converted into thermal deformation and the monitoring results are output. When the thermal deformation exceeds the preset threshold, an early warning signal is triggered.

[0054] The above step S1 specifically includes: Specifically, the integrated ceramic core-shell sample with built-in piezoelectric sensing, as proposed in the first aspect, was calibrated under experimental conditions. The electrical signal of the built-in piezoelectric sensing unit was excited and read using a precision impedance analyzer to obtain its initial resonant frequency. The actual deformation of the sample during heating was simultaneously measured using a thermomechanical analyzer or other high-precision deformation measurement device. By applying different thermal loads, multiple sets of data corresponding to the resonant frequency shift and the actual thermal deformation were obtained. A linear correlation model between the resonant peak shift of the piezoelectric sensing unit and the thermal deformation of the ceramic core-shell was established by linear fitting of multiple sets of data using a computer, thus completing the model establishment and calibration. The linear correlation model between the resonant peak shift of the piezoelectric sensing unit and the thermal deformation of the ceramic core-shell is as follows:

[0055] in, This represents the actual thermal deformation. K For calibration coefficients, ΔFr This represents the resonant frequency offset.

[0056] The above step S2 specifically includes: Specifically, the integrated ceramic core and shell with a built-in piezoelectric sensor to be monitored is placed in a high-temperature box furnace, and its piezoelectric sensing unit is connected to an external precision impedance analyzer via a signal transmission line. The box furnace is controlled to operate according to a preset heating-holding-cooling process curve to simulate the actual thermal processing environment. Simultaneously, the impedance analyzer continuously excites the piezoelectric sensing unit with a set scanning frequency and measurement accuracy, and dynamically records the real-time changes in its resonant frequency.

[0057] Optionally, the scanning frequency of the impedance analyzer is set to no less than 1 scan per second to ensure the capture of the dynamic process of thermal deformation.

[0058] The above step S3 specifically includes: Specifically, using the calibration model pre-established and stored in step S1, the real-time acquired resonant frequency offset is converted into the corresponding thermal deformation of the ceramic core and shell. The changes in thermal deformation over time or temperature are then displayed and output in real-time as data charts or curves for operator monitoring and analysis. The calculated thermal deformation is compared in real-time with a preset safety threshold; when the monitored thermal deformation exceeds the safety threshold, an audible and visual alarm is triggered or a warning message is sent to the control terminal to prompt operators to adjust process parameters promptly.

[0059] The above are merely several specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0060] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0061] It should be noted that, in the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. An integrated piezoelectric sensing ceramic core shell, characterized by, The ceramic matrix is formed by an additive manufacturing process. At least one piezoelectric sensing unit is built into a monitoring area of the ceramic matrix by an additive manufacturing process, the piezoelectric sensing unit comprising a piezoelectric ceramic layer and a polarization electrode layer formed on the surface thereof; A protective shell is formed by an additive manufacturing process and encapsulates the piezoelectric sensing unit; A signal transmission line is formed by an additive manufacturing process synchronously with the protective shell and is embedded in the protective shell, one end of the signal transmission line being connected to the polarization electrode layer and the other end extending to the outer surface of the ceramic core shell. The monitoring area is determined based on thermal-mechanical coupling simulation analysis of the ceramic core shell during hot working, and the monitoring area is an area in which the equivalent stress value exceeds a preset stress threshold or the total deformation exceeds a preset deformation threshold in the simulation results.

2. The integrated piezoelectrically-sensed ceramic core shell of claim 1, wherein: A fitting gap for compensating for sintering shrinkage is formed between the protective shell and the ceramic matrix, and the fitting gap has a value in the range of 30-70 µm.

3. The integrated piezoelectrically-sensed ceramic core shell of claim 2, wherein: The method comprises the following steps:

4. A method for producing an integrated piezoelectric sensor- ceramic core-shell for producing an integrated piezoelectric sensor-ceramic core-shell according to any one of claims 1 to 3, characterized in that S1. Determining a monitoring area of the ceramic matrix based on thermal-mechanical coupling simulation analysis, and constructing a three-dimensional digital model of the ceramic core shell; S2. Printing the ceramic matrix based on the three-dimensional digital model using an additive manufacturing process; S3. Printing the piezoelectric sensing unit and its polarization electrode in the monitoring area of the ceramic matrix using an additive manufacturing process; S4. Printing the protective shell encapsulating the piezoelectric sensing unit and synchronously printing the signal transmission line by a multi-material additive manufacturing process; S5. Sintering the green body printed in step S4; S6. Polarizing the piezoelectric sensing unit through the signal transmission line. In step S1, the three-dimensional digital model of the ceramic core shell is constructed by constructing a three-dimensional digital model of the ceramic matrix fused with the piezoelectric sensing unit, the protective shell, and the signal transmission line; wherein an installation groove is generated in the monitoring area of the ceramic matrix, the inner cavity shape of the installation groove being complementary to the outer shape of the protective shell; and the layout path of the signal transmission line is planned.

5. The method of claim 4, wherein: In step S2, the ceramic matrix with the installation groove is printed by controlling the printing layer thickness and exposure energy using light-curing 3D printing; wherein the solid content of the silica-based ceramic slurry used is 75-86 wt%, and the ceramic powder particle size is 1-20 µm; the layer thickness of the light-curing 3D printing is 40-80 µm, and the single-layer exposure energy is 40-70 mW.

6. The method of claim 4, wherein: In step S3, the piezoelectric sensing unit is printed by micro-droplet jetting technology, and the piezoelectric ceramic slurry with a solid content of 75-86 wt% is filled into the installation groove, and the temperature during the printing process is 80-120 °C.

7. The method of claim 4, wherein: In step S5, the sintering process comprises: heating to 500-650 °C in an air atmosphere and holding to complete debinding, and then heating to 1100-1350 °C in an argon protective atmosphere and sintering and holding.

8. The method of claim 4, wherein: In step S6, the polarization process comprises: applying a direct current electric field of 1-5 kV / mm in a polarization liquid environment at a temperature of 150-220 °C for 10-50 min.

9. The method of claim 4, wherein: The method comprises the following steps:

10. A method of monitoring an integrated piezoelectric sensored ceramic core shell for use in monitoring an integrated piezoelectric sensored ceramic core shell as claimed in any one of claims 1 to 3, characterised by, ​ A corresponding relationship model between the resonance frequency offset of the piezoelectric sensing unit and the thermal deformation of the ceramic core shell is established through experimental calibration; During the hot working process, the resonance frequency data of the piezoelectric sensing unit are collected in real time; The collected resonance frequency data are converted into the thermal deformation based on the established corresponding relationship model, and a monitoring result is outputted, and when the thermal deformation exceeds a preset threshold, a warning is triggered.

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