3D-printed piezoelectric ceramic and preparation method and application thereof

Abstract

The application discloses a 3D printing piezoelectric ceramic and a preparation method and application thereof, relates to the technical field of piezoelectric ceramic additive manufacturing, and a polarization method comprises the following steps: firstly performing wax sealing treatment on the sintered ceramic, then brushing conductive silver paste on the surface of the ceramic to form an electrode; the piezoelectric ceramic is placed in silicon oil, an electric field is applied to perform polarization treatment, and a 3D printing piezoelectric ceramic is obtained; wherein the wax sealing treatment selects molten single paraffin wax, microcrystalline wax or a mixture thereof, the porous piezoelectric ceramic is placed in the molten wax, and the molten wax is infiltrated into the pores by adopting a vacuum wax infiltration or step-by-step pressure infiltration treatment mode, and the porous piezoelectric ceramic is exposed on the surface after cooling and solidification for silver brushing. The method effectively improves the structural integrity and piezoelectric performance of the ceramic printing component, and is particularly suitable for the preparation and polarization treatment of piezoelectric devices with special-shaped or porous structures.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric ceramic additive manufacturing technology, specifically to a 3D printed piezoelectric ceramic, its preparation method, and its application. Background Technology

[0002] Piezoelectric ceramics are widely used in electronic devices such as sensors, actuators, and energy harvesters due to their excellent electromechanical coupling properties. However, traditional piezoelectric ceramic fabrication techniques (such as dry pressing, tape casting, and injection molding) have the following limitations:

[0003] (1) Limited by complex structures: Traditional methods rely on mold forming, which makes it difficult to realize complex three-dimensional structures such as porous, suspended, and irregular shapes. Moreover, the mold cost is high and the development cycle is long. (2) Low material utilization: Cutting and processing can easily lead to material waste, especially for high-cost piezoelectric ceramics (such as lead zirconate titanate PZT), which is less economical. (3) Insufficient performance uniformity: Traditional processes can easily introduce internal stress or component segregation, which affects the piezoelectric constant (such as d33) and electromechanical conversion efficiency.

[0004] In recent years, 3D printing technology has provided new ideas for the manufacture of piezoelectric ceramics, but existing additive manufacturing methods and polarization techniques for preparing piezoelectric ceramics still have significant drawbacks:

[0005] (1) Photopolymerization molding (SLA / DLP): It relies on the blending of photosensitive resin and ceramic powder, and requires high-temperature debinding, which can easily lead to structural deformation or performance degradation; (2) Selective laser sintering (SLS): High-energy laser local heating can easily induce cracks, and the ceramic density is low, which makes it difficult to meet the high performance requirements of piezoelectric devices; (3) Fused deposition modeling (FDM): It is limited by low ceramic filling amount (usually <60 vol%), and the shrinkage rate after sintering is large, making it difficult to control the dimensional accuracy; (4) Existing polarization methods usually involve installing copper sheets on both sides of the ceramic to prepare electrodes for polarization. However, for porous and complex piezoelectric ceramics, it is not possible to ensure complete adhesion with copper sheets, or even to prepare electrodes, thus making it impossible to achieve polarization and resulting in unsatisfactory piezoelectric performance.

[0006] In view of the above, this application is hereby submitted. Summary of the Invention

[0007] This invention addresses the problems of poor slurry rheological properties, difficulty in polarizing complex structures, and low molding accuracy in existing piezoelectric ceramic direct-write printing technology. It provides a 3D printed piezoelectric ceramic, its preparation method, and its application. This method effectively improves the structural integrity and piezoelectric properties of ceramic printed components, and is particularly suitable for the preparation and polarization treatment of irregularly shaped or porous piezoelectric devices.

[0008] This invention is achieved through the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing 3D printed piezoelectric ceramics, comprising the following steps:

[0010] Three-dimensional printing was performed on piezoelectric ceramic slurry to obtain a porous piezoelectric ceramic preform with a complex structure.

[0011] After drying, degreasing and sintering, porous piezoelectric ceramics are obtained.

[0012] The sintered ceramic is first wax-sealed, and then conductive silver paste is brushed onto its surface to form electrodes.

[0013] Piezoelectric ceramics are placed in silicone oil and polarized by applying an electric field to obtain 3D printed piezoelectric ceramics.

[0014] During the 3D printing process, the layer thickness is set to 0.1mm to 0.5mm, the printing speed is 5mm / s to 30mm / s, the infill rate is 50% to 100%, and the printing temperature is maintained within the range of 50℃ to 100℃ by a heated bed and barrel heating device.

[0015] The polarization treatment is carried out in a silicone oil medium with an electric field strength of 2kV / mm to 5kV / mm, a polarization temperature of 80℃ to 120℃, and a polarization time of 10min to 30min.

[0016] The drying temperature is 60℃~100℃, and the drying time is 12h~24h.

[0017] The degreasing temperature is 200℃~500℃, the degreasing heating rate is 0.3℃ / min~0.7℃ / min, the holding time is 1h~3h, the sintering temperature is 1000℃~1300℃, and the holding time is 2h~4h.

[0018] Preferably, the degreasing process should ensure slow removal of organic matter from the green body. First, at 0–200℃, with a heating rate of 0.3–0.6℃ / min, hold for 1–2 hours to remove free water, water of crystallization, and other moisture from the green body. Then, at 200–500℃, with a heating rate of 0.4–0.7℃ / min, hold for 2–3 hours to allow the organic matter in the green body to decompose and volatilize, achieving degreasing. Finally, from 500℃ to the densification temperature, with a heating rate of 0.4–0.7℃ / min, hold for 2–6 hours to increase the density of the green body. The densification temperature is generally about 300℃ lower than the sintering temperature.

[0019] This invention, during polarization treatment, first encapsulates the porous piezoelectric ceramic with wax, then coats the surface with silver to prepare electrodes. This avoids direct contact between the positive and negative electrodes, thereby achieving polarization of the piezoelectric ceramic and imbuing it with piezoelectric properties. It enables high-precision printing of complex structures and intricate internal designs to obtain piezoelectric ceramic devices that meet performance requirements. Simultaneously, using vacuum wax infiltration or stepwise pressure wax infiltration improves the pore sealing rate, and wax infiltration can be repeated 1-3 times to enhance sealing and polarization stability. Cooling can be achieved through a combination of natural cooling and circulating water cooling to reduce thermal stress and prevent crack formation.

[0020] In one specific embodiment, the wax sealing treatment uses molten single paraffin wax, microcrystalline wax, or a mixture thereof. The porous piezoelectric ceramic is placed in the molten wax, and the molten wax is penetrated into the pores by vacuum wax infiltration or stepwise pressure wax infiltration. After cooling and solidification, the surface of the porous piezoelectric ceramic is exposed for silvering.

[0021] In one specific embodiment, when preparing a porous piezoelectric ceramic preform, a direct-write molding method is used to perform three-dimensional printing of the piezoelectric ceramic slurry.

[0022] This invention utilizes direct-write 3D printing technology to enable the rapid manufacturing of piezoelectric ceramic devices with complex shapes and intricate internal structures.

[0023] In one specific embodiment, the piezoelectric ceramic slurry is composed of the following components by mass percentage: 65wt% to 75wt% lead zirconate titanate-based piezoelectric ceramic powder, 0.5wt% to 1.0wt% dispersant, 2wt% to 5wt% glycerol, 2wt% to 4wt% first-stage binder (preferably PVA or PVP aqueous solution), 1wt% to 3wt% second-stage binder (preferably microcapsules with epoxy or furfuryl alcohol resin as the core material and gelatin-chitosan complex as the shell material), and the balance being deionized water.

[0024] In one specific embodiment, the first-stage binder includes a water-soluble thermoplastic polymer (such as polyvinyl alcohol PVA), and the second-stage binder includes a microcapsule-encapsulated thermosetting low-molecular-weight resin (such as epoxy resin or sugar alcohol resin), wherein the microcapsule coating layer is composed of a composite of soluble gelatin and chitosan.

[0025] The specific preparation process of the microcapsule coating layer is as follows:

[0026] A 5% aqueous solution of gelatin and a 1% solution of chitosan acetate were mixed at a volume ratio of 3:1 and the pH was adjusted to 5.5 to form the wall material solution. A thermosetting low molecular weight resin was used as the core material oil phase and emulsified to form 1–5 μm oil droplets. The temperature was gradually lowered under stirring and the pH was adjusted to 4.8 to initiate a re-coagulation reaction, which allowed the gelatin-chitosan to deposit on the surface of the oil droplets to form a film. Subsequently, glutaraldehyde solution was added dropwise for cross-linking and curing. The film was then centrifuged, washed, and freeze-dried to obtain epoxy resin microcapsules with a gelatin-chitosan shell.

[0027] The method for preparing the microcapsule coating layer of gelatin-chitosan epoxy resin microcapsules significantly improves the interlayer bonding and molding quality of the preform, not only reducing the cracking rate of the preform but also increasing the density of the ceramic and improving the piezoelectric properties.

[0028] The particle size of the second-stage binder is 0.5μm to 5μm.

[0029] Traditional slurries suffer from problems such as poor interlayer bonding and poor extrusion stability in direct-write printing. Higher viscosity requires larger nozzles for printing, resulting in lower preform accuracy, while lower viscosity leads to poorer extrusion and platen forming. Therefore, slurries need to meet the requirements of shear thinning index (n = 0.2-0.6) and thixotropic recovery index (30s recovery > 90%).

[0030] This invention optimizes the slurry formulation, designing a slurry with a high solids content (66-80 wt%) to ensure the slurry maintains molding accuracy. Simultaneously, by optimizing the proportions of other components, the slurry achieves ideal rheological properties and printing accuracy during 3D printing. The dispersant, through an electrostatic stabilization mechanism, generates a Zeta potential (absolute value > 30 mV) on the surface of ceramic particles by adsorbing its anionic groups, inhibiting agglomeration caused by van der Waals forces and ensuring fluidity even with a solids content > 50 vol%. Deionized water regulates rheological properties; its dielectric constant (ε ≈ 80) affects the dispersant's ionization efficiency, and its low ion content (conductivity < 5 μS / cm) avoids flocculation caused by impurity ion bridging, ensuring slurry stability. The introduced dual-stage controllable release organic binder system achieves a balance between high fluidity in the printing stage and high strength in the molding stage through directional coating of particle surfaces and subsequent thermally triggered release. Simultaneously, a controllable microporous structure is formed during the debinding stage to alleviate shrinkage stress. This invention optimizes the rheological properties of the slurry through the synergistic effect of the above components, enabling the slurry to simultaneously possess characteristics of high solid content, shear thinning index n < 0.5, and viscosity of 100 Pa·s to 1000 Pa·s, thereby meeting the requirements of continuous extrusion and structural self-support, and realizing high-precision printing of complex structures and fine internal designs.

[0031] In one specific embodiment, the method for preparing the piezoelectric ceramic slurry includes the following steps:

[0032] Add a dispersant to deionized water, stir to dissolve, then add lead zirconate titanate-based piezoelectric ceramic powder, stir magnetically, and perform ultrasonic treatment to allow the dispersant to be adsorbed on the surface of the lead zirconate titanate-based piezoelectric ceramic powder.

[0033] Add the first-stage binder, degas and stir or stir at low shear, then add glycerin and continue stirring;

[0034] After adding a second-stage binder, low-shear back mixing, vacuum degassing, and standing to remove bubbles, piezoelectric ceramic slurry is obtained.

[0035] The prepared piezoelectric ceramic slurry exhibits shear-thinning rheological properties, meeting the following criteria: shear-thinning index n = 0.2–0.6, thixotropic recovery rate > 90%, and viscosity range of 100 Pa·s to 1000 Pa·s.

[0036] In the preparation of the piezoelectric ceramic slurry of this invention, a dispersant is first uniformly adsorbed onto the surface of the ceramic powder, and then a first-stage binder solution and a second-stage microcapsules are added sequentially. The slurry is then shaped using a low-shear mixing combined with vacuum degassing process. This system can improve the mechanical strength of the blank in a short time after printing, reduce deformation and collapse during handling or drying, and release uniform micropores through the decomposition of the second-stage binder during the debinding stage to alleviate sintering shrinkage stress and reduce the risk of cracking.

[0037] In one specific embodiment, the lead zirconate titanate-based piezoelectric ceramic powder is composed of 0.25Pb(Zn1 / 3Nb2 / 3)O3–0.75Pb. 0.06 La 0.04 (Zr 0.53 Ti 0.47 The powder is based on O3 and doped with 0.5 wt% Sb2O5. The PZN–PLZT solid solution system combined with Sb2O5 doping can simultaneously improve dielectric temperature stability, suppress excessive grain growth, and reduce oxygen vacancy concentration, thereby improving insulation and polarization stability at high temperatures.

[0038] The preparation method of lead zirconate titanate-based piezoelectric ceramic powder is as follows: Lead zirconate titanate powder is prepared by oxide solid-state reaction method. First, Pb3O4 (99%), Sb2O5 (99.95%), ZrO2 (99%), TiO2 (99%), Nb2O5 (99.99%), ZnO (99%), and La2O3 (99.95%) raw materials are weighed and mixed according to the stoichiometric ratio. The mixture is then placed in a ball mill, and a certain amount of anhydrous ethanol is added. The mixture is thoroughly ball-milled and mixed evenly at a certain speed. After drying, the mixture is transferred to a high-temperature furnace and pre-sintered at 800-900℃ for 2-3 hours. Then, a second ball milling is performed to obtain lead zirconate titanate piezoelectric ceramic powder.

[0039] This invention introduces La into lead zirconate titanate piezoelectric ceramic powder. 3+ Constructing a PZN–PLZT solid solution system can further improve its dielectric temperature stability and electrical reliability. At the same time, doping with a small amount of Sb2O5 helps to suppress excessive grain growth during sintering and reduce leakage current caused by oxygen vacancies, thereby improving the overall electrical performance.

[0040] In one specific embodiment, the piezoelectric ceramic paste is heated in a water bath at 50°C to 100°C and degassed before printing.

[0041] This invention first heats the slurry at 50℃ to 100℃ before introducing it into the printing platform to further improve its fluidity and give it suitable rheological properties. This allows the slurry to flow more smoothly in subsequent processing, reducing problems such as clogging and uneven distribution caused by excessively high slurry viscosity. Then, the slurry is introduced into a 3D printing heated bed and barrel heating device with a controllable temperature of 1℃ to 100℃ to ensure that the printing substrate is at a suitable temperature. Its uniform temperature structure can reduce the temperature difference on the heated bed surface and avoid defects such as shrinkage deformation and poor interlayer bonding during piezoelectric ceramic molding, thereby improving molding quality and performance.

[0042] Thirdly, this application provides a 3D printed piezoelectric ceramic, which is made using the above-described preparation method.

[0043] Fourthly, this application provides an electronic device including the aforementioned 3D-printed piezoelectric ceramic.

[0044] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0045] (1) The present invention adopts a combination of wax encapsulation and silver electrode to fill the pores and avoid polarization short circuits, while ensuring complete electrode coverage, which effectively improves the structural integrity and piezoelectric performance of ceramic printed components. It can be widely used for piezoelectric components with irregular structures such as through holes and cavities, and is especially suitable for the preparation and polarization treatment of irregular or porous piezoelectric devices.

[0046] (2) The piezoelectric ceramic slurry used in this invention has both high shear thinning properties and structural recovery ability by adjusting the solid content and added components. It can achieve stable extrusion and high shape retention, effectively avoiding nozzle clogging and green body deformation.

[0047] (3) This invention controls grain growth and internal defects through a slow-heating, segmented debinding and dense sintering process, combined with an excellent polarization method, to achieve d 33 High-performance device output with a value greater than 450pC / N.

[0048] (4) This invention can be adapted to various piezoelectric ceramic compositions and is suitable for the customized production of miniaturized and multifunctional smart devices, with significant industrial application prospects.

[0049] (5) La is introduced into the 0.25PZN–0.75PLZT solid solution powder used in this invention. 3+ Doping with a small amount of Sb2O5 can improve dielectric temperature stability and electrical reliability, suppress excessive grain growth during sintering, and reduce leakage current caused by oxygen vacancies, so that the sintered piezoelectric ceramics exhibit higher insulation resistance and better piezoelectric response during polarization. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0051] Figure 1 These are photographs of ceramic green bodies prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention, wherein (a) represents Example 1, (b) represents Example 2, (c) represents Example 3, (d) represents Comparative Example 1, (e) represents Comparative Example 2, and (f) represents Comparative Example 3.

[0052] Figure 2 Copper sheet polarization was introduced into the ceramic sample prepared in Comparative Example 2 of this invention;

[0053] Figure 3 The ceramic sample prepared in Comparative Example 3 of this invention was directly polarized by brushing with silver.

[0054] Figure 4 The ceramic sample prepared in Example 1 of this invention was wax-sealed and then coated with silver for polarization. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0056] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0057] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those different embodiments or examples.

[0058] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0059] Example 1

[0060] This embodiment provides a method for preparing piezoelectric ceramics based on direct-write forming 3D printing. The specific preparation steps are as follows:

[0061] S1. The general structural formula for 0.25PZN–0.75PLZT piezoelectric ceramic powder is:

[0062] 0.25Pb(Zn1 / 3Nb2 / 3)O3–0.75Pb 0.06 La 0.04 (Zr 0.53 Ti 0.47Weigh out Pb3O4 (99%), Sb2O5 (99.95%), ZrO2 (99%), TiO2 (99%), Nb2O5 (99.99%), ZnO (99%), and La2O3 (99.95%), with Sb2O5 added at 0.5% of the total mass. Place the mixture in a polytetrafluoroethylene ball mill jar, using anhydrous ethanol as the medium. The weight ratio of anhydrous ethanol to powder is 2:1. Place the mixture in a planetary ball mill and mill for 12 hours. After milling, remove the slurry and dry it in an oven at 80°C. Then place it on an alumina crucible and heat it in a muffle furnace at a heating rate of 5°C / min to 800°C and hold it at that temperature for 3 hours to complete the first sintering.

[0063] S2. The pre-fired powder was placed in a polytetrafluoroethylene ball mill jar with anhydrous ethanol as the dispersion medium. The weight ratio of anhydrous ethanol to powder was 2:1. The mixture was ball-milled twice at 600 rpm for 12 hours using a planetary ball mill. The slurry was then dried in an oven at 80°C. The dried powder was the 0.25PZN–0.75PLZT piezoelectric ceramic powder. This formulation system maintains a high Curie temperature while inhibiting grain coarsening through the introduction of Sb2O5, which helps to improve subsequent polarization uniformity and high-temperature stability.

[0064] S3. Add 0.5g of dispersant to 20ml of deionized water, stir to dissolve, then add 70g of lead titanate-based piezoelectric ceramic powder. Stir magnetically and sonicate to allow the dispersant to adsorb onto the powder surface. Add 3g of the first-stage binder (polyvinyl alcohol PVA), stir to remove bubbles or stir under low shear, then add 2g of glycerin and continue stirring. Add 1g of the second-stage binder (microcapsule-coated epoxy resin with a particle size of about 3μm), mix under low shear and then vacuum degas. After standing to remove bubbles, the piezoelectric ceramic slurry is obtained.

[0065] The specific preparation process of the microcapsule coating layer is as follows:

[0066] A 5% gelatin aqueous solution and a 1% chitosan acetate solution were mixed at a volume ratio of 3:1 and the pH was adjusted to 5.5 to form the wall material solution. A thermosetting low molecular weight resin was used as the core material oil phase and emulsified to form 3μm oil droplets. The temperature was gradually lowered under stirring and the pH was adjusted to 4.8 to initiate a re-coagulation reaction, which allowed the gelatin-chitosan to deposit on the surface of the oil droplets to form a film. Subsequently, glutaraldehyde solution was added dropwise for cross-linking and curing. The film was then centrifuged, washed, and freeze-dried to obtain epoxy resin microcapsules with a gelatin-chitosan shell.

[0067] S4. Heat the piezoelectric ceramic slurry in an 80℃ water bath, transfer it to a syringe for degassing, and then place it on the printing platform. The printing platform incorporates a 3D printing heated bed and a syringe heating device. Set the printing speed to 30mm / s, printing height to 2mm, layer thickness to 0.5mm, printing size to 30×30×1mm, fill rate to 50%, and nozzle inner diameter to 0.6mm. The printed object is shown in the image. Figure 1 As shown in (a);

[0068] S5. Debinding and Sintering: The printed sample is first dried in an oven at 60℃ for 12 hours, and then debinding is performed in three stages. First, the temperature is increased to 200℃ at 0.6℃ / min and held for 1 hour to remove free water, crystal water and other moisture from the green body. Second, the temperature is increased to 500℃ at 0.7℃ / min and held for 2 hours to decompose and volatilize the organic matter in the green body. Third, the temperature is increased to 780℃ at 0.7℃ / min and held for 2 hours to increase the density. After debinding, the sample is heated to 1000℃ in a muffle furnace at a rate of 5℃ / min, and then increased to 1250℃ at 2℃ / min and held for 2 hours.

[0069] S6. Sample Polarization: After sintering, the printed ceramic sample is encapsulated with wax. During the wax encapsulation process, the sample is first placed in a vacuum chamber and evacuated for 2 minutes, then molten wax is introduced for penetration to improve the pore sealing rate. During cooling, the temperature is first allowed to drop naturally to 40°C, followed by water cooling to reduce the shrinkage stress of the wax layer. Then, a layer of wax is ground off until the sample is exposed. One side is then brushed with silver, and the other side is brushed with silver in the same way to effectively prevent the positive and negative electrodes from connecting, facilitating polarization. The polarization treatment conditions are: a DC electric field is applied in a silicone oil bath with an electric field strength of 2kV / mm, a treatment temperature of 80°C, and a polarization time of 20 minutes.

[0070] Example 2

[0071] This embodiment provides a method for preparing piezoelectric ceramics based on direct-write 3D printing. Unlike Embodiment 1, the amount of each raw material component used in preparing the piezoelectric ceramic slurry differs in this embodiment. The specific preparation steps are as follows:

[0072] S1. The general structural formula for 0.25PZN–0.75PLZT piezoelectric ceramic powder is:

[0073] 0.25Pb(Zn1 / 3Nb2 / 3)O3–0.75Pb 0.06 La 0.04 (Zr 0.53 Ti 0.47Weigh out Pb3O4 (99%), Sb2O5 (99.95%), ZrO2 (99%), TiO2 (99%), Nb2O5 (99.99%), ZnO (99%), and La2O3 (99.95%), with Sb2O5 added at 0.5% of the total mass. Place the mixture in a polytetrafluoroethylene ball mill jar, using anhydrous ethanol as the medium. The weight ratio of anhydrous ethanol to powder is 2:1. Place the mixture in a planetary ball mill and mill for 12 hours. After milling, remove the slurry and dry it in an oven at 80°C. Then place it on an alumina crucible and heat it in a muffle furnace at a heating rate of 5°C / min to 800°C and hold it at that temperature for 3 hours to complete the first sintering.

[0074] S2. Place the pre-fired powder into a polytetrafluoroethylene ball mill jar and use anhydrous ethanol as the dispersion medium. The weight ratio of anhydrous ethanol to powder is 2:1. Use a planetary ball mill at 600 rpm for 12 hours. After removing the slurry, dry it in an oven at 80°C. The dried powder is 0.25PZN–0.75PLZT piezoelectric ceramic powder.

[0075] S3. Add 0.5g of dispersant to 20ml of deionized water, stir to dissolve, then add 70g of lead titanate-based piezoelectric ceramic powder. Stir magnetically and sonicate to allow the dispersant to adsorb onto the powder surface. Add 3g of the first-stage binder (polyvinyl alcohol PVA), stir to remove bubbles or stir under low shear, then add 2g of glycerin and continue stirring. Add 1g of the second-stage binder (microcapsule-coated epoxy resin, particle size 1–5μm), stir under low shear back mixing, then vacuum degas, and allow to stand to remove bubbles to obtain the piezoelectric ceramic slurry.

[0076] The specific preparation process of the microcapsule coating layer is as follows:

[0077] A 5% gelatin aqueous solution and a 1% chitosan acetate solution were mixed at a volume ratio of 3:1 and the pH was adjusted to 5.5 to form the wall material solution. A thermosetting low molecular weight resin was used as the core material oil phase and emulsified to form 3μm oil droplets. The temperature was gradually lowered under stirring and the pH was adjusted to 4.8 to initiate a re-coagulation reaction, which allowed the gelatin-chitosan to deposit on the surface of the oil droplets to form a film. Subsequently, glutaraldehyde solution was added dropwise for cross-linking and curing. The film was then centrifuged, washed, and freeze-dried to obtain epoxy resin microcapsules with a gelatin-chitosan shell.

[0078] S4. Heat the piezoelectric ceramic slurry in a water bath at 50-100℃, transfer it to a syringe for degassing, and then place it on the printing platform. The printing platform incorporates a 3D printing heated bed and a syringe heating device. Set the printing speed to 30mm / s, printing height to 2mm, layer thickness to 0.5mm, printing size to 30×30×1mm, fill rate to 50%, and nozzle inner diameter to 0.6mm. The printed product image is shown below. Figure 1 As shown in (b);

[0079] S5. Debinding and Sintering: The printed sample is first dried in an oven at 60℃ for 12 hours, and then debinding is performed in three stages. First, the temperature is increased to 200℃ at 0.6℃ / min and held for 1 hour to remove free water, crystal water and other moisture from the green body. Second, the temperature is increased to 500℃ at 0.7℃ / min and held for 2 hours to decompose and volatilize the organic matter in the green body. Third, the temperature is increased to 780℃ at 0.7℃ / min and held for 2 hours to increase the density. After debinding, the sample is heated to 1000℃ in a muffle furnace at a rate of 5℃ / min, and then increased to 1250℃ at 2℃ / min and held for 2 hours.

[0080] S6. Sample Polarization: After sintering, the printed ceramic sample is encapsulated with wax. During the wax encapsulation process, the sample is first placed in a vacuum chamber and evacuated for 2 minutes, then molten wax is introduced for penetration to improve the pore sealing rate. During cooling, the temperature is first allowed to drop naturally to 40°C, followed by water cooling to reduce the shrinkage stress of the wax layer. Then, a layer of wax is ground off until the sample is exposed. One side is then brushed with silver, and the other side is brushed with silver in the same way to effectively prevent the positive and negative electrodes from connecting, facilitating polarization. The polarization treatment conditions are: a DC electric field is applied in a silicone oil bath with an electric field strength of 2kV / mm, a treatment temperature of 80°C, and a polarization time of 20 minutes.

[0081] Example 3

[0082] This embodiment provides a method for preparing piezoelectric ceramics based on direct-write 3D printing. Unlike Embodiment 1, the amount of each raw material component used in preparing the piezoelectric ceramic slurry differs in this embodiment. The specific preparation steps are as follows:

[0083] S1. The general structural formula for 0.25PZN–0.75PLZT piezoelectric ceramic powder is:

[0084] 0.25Pb(Zn1 / 3Nb2 / 3)O3–0.75Pb 0.06 La 0.04 (Zr 0.53 Ti 0.47 Weigh out Pb3O4 (99%), Sb2O5 (99.95%), ZrO2 (99%), TiO2 (99%), Nb2O5 (99.99%), ZnO (99%), and La2O3 (99.95%), with Sb2O5 added at 0.5% of the total mass. Place the mixture in a polytetrafluoroethylene ball mill jar, using anhydrous ethanol as the medium. The weight ratio of anhydrous ethanol to powder is 2:1. Place the mixture in a planetary ball mill and mill for 12 hours. After milling, remove the slurry and dry it in an oven at 80°C. Then place it on an alumina crucible and heat it in a muffle furnace at a heating rate of 5°C / min to 800°C and hold it at that temperature for 3 hours to complete the first sintering.

[0085] S2. Place the pre-fired powder into a polytetrafluoroethylene ball mill jar and use anhydrous ethanol as the dispersion medium. The weight ratio of anhydrous ethanol to powder is 2:1. Use a planetary ball mill at 600 rpm for 12 hours. After removing the slurry, dry it in an oven at 80°C. The dried powder is 0.25PZN–0.75PLZT piezoelectric ceramic powder.

[0086] S3. Add 0.5g of dispersant to 20ml of deionized water, stir to dissolve, then add 70g of lead titanate-based piezoelectric ceramic powder. Stir magnetically and sonicate to allow the dispersant to adsorb onto the powder surface. Add 3g of the first-stage binder (polyvinyl alcohol PVA), stir to remove bubbles or stir under low shear, then add 2g of glycerin and continue stirring. Add 1g of the second-stage binder (microcapsule-coated epoxy resin, particle size 1–5μm), stir under low shear back mixing, then vacuum degas, and allow to stand to remove bubbles to obtain the piezoelectric ceramic slurry.

[0087] The specific preparation process of the microcapsule coating layer is as follows:

[0088] A 5% gelatin aqueous solution and a 1% chitosan acetate solution were mixed at a volume ratio of 3:1 and the pH was adjusted to 5.5 to form the wall material solution. A thermosetting low molecular weight resin was used as the core material oil phase and emulsified to form 3μm oil droplets. The temperature was gradually lowered under stirring and the pH was adjusted to 4.8 to initiate a re-coagulation reaction, which allowed the gelatin-chitosan to deposit on the surface of the oil droplets to form a film. Subsequently, glutaraldehyde solution was added dropwise for cross-linking and curing. The film was then centrifuged, washed, and freeze-dried to obtain epoxy resin microcapsules with a gelatin-chitosan shell.

[0089] S4. Heat the piezoelectric ceramic slurry in a water bath at 50-100℃, transfer it to a syringe for degassing, and then place it on the printing platform. The printing platform incorporates a 3D printing heated bed and a syringe heating device. Set the printing speed to 30mm / s, printing height to 2mm, layer thickness to 0.5mm, printing size to 30×30×1mm, fill rate to 50%, and nozzle inner diameter to 0.6mm. The printed product image is shown below. Figure 1 As shown in (c);

[0090] S5. Debinding and Sintering: The printed sample is first dried in an oven at 60℃ for 12 hours, and then debinding is performed in three stages. First, the temperature is increased to 200℃ at 0.6℃ / min and held for 1 hour to remove free water, crystal water and other moisture from the green body. Second, the temperature is increased to 500℃ at 0.7℃ / min and held for 2 hours to decompose and volatilize the organic matter in the green body. Third, the temperature is increased to 780℃ at 0.7℃ / min and held for 2 hours to increase the density. After debinding, the sample is heated to 1000℃ in a muffle furnace at a rate of 5℃ / min, and then increased to 1250℃ at 2℃ / min and held for 2 hours.

[0091] S6. Sample Polarization: After sintering, the printed ceramic sample is encapsulated with wax. During the wax encapsulation process, the sample is first placed in a vacuum chamber and evacuated for 2 minutes, then molten wax is introduced for penetration to improve the pore sealing rate. During cooling, the temperature is first allowed to drop naturally to 40°C, followed by water cooling to reduce the shrinkage stress of the wax layer. Then, a layer of wax is ground off until the sample is exposed. One side is then brushed with silver, and the other side is brushed with silver in the same way to effectively prevent the positive and negative electrodes from connecting, facilitating polarization. The polarization treatment conditions are: a DC electric field is applied in a silicone oil bath with an electric field strength of 2kV / mm, a treatment temperature of 80°C, and a polarization time of 20 minutes.

[0092] Comparative Example 1

[0093] This comparative example provides a method for preparing piezoelectric ceramics based on direct-write 3D printing. Unlike Example 1, the piezoelectric ceramic powder in this comparative example does not incorporate a two-stage binder system. The specific preparation steps are as follows:

[0094] S1. The general structural formula for 0.25PZN–0.75PLZT piezoelectric ceramic powder is:

[0095] 0.25Pb(Zn1 / 3Nb2 / 3)O3–0.75Pb 0.06 La 0.04 (Zr 0.53 Ti 0.47 Weigh out Pb3O4 (99%), Sb2O5 (99.95%), ZrO2 (99%), TiO2 (99%), Nb2O5 (99.99%), ZnO (99%), and La2O3 (99.95%), place them in a polytetrafluoroethylene ball mill jar, use anhydrous ethanol as the medium, and add anhydrous ethanol to powder in a weight ratio of 2:1. Place the mixture in a planetary ball mill and ball mill for 12 hours. After the slurry is removed, it is dried in an oven at 80°C, then placed on an alumina crucible and heated to 800°C in a muffle furnace at a heating rate of 5°C / min, and held at that temperature for 3 hours to complete the first sintering.

[0096] S2. Place the pre-fired powder into a polytetrafluoroethylene ball mill jar and use anhydrous ethanol as the dispersion medium. The weight ratio of anhydrous ethanol to powder is 2:1. Use a planetary ball mill at 600 rpm for 12 hours. After removing the slurry, dry it in an oven at 80°C. The dried powder is 0.25PZN–0.75PLZT piezoelectric ceramic powder.

[0097] S3. Add dispersant to 20ml of deionized water, stir to dissolve, then add lead zirconate titanate-based piezoelectric ceramic powder, stir magnetically, and sonicate to allow the dispersant to adsorb onto the surface of the lead zirconate titanate-based piezoelectric ceramic powder. After low-shear back mixing, vacuum degassing is performed, and after standing to remove bubbles, piezoelectric ceramic slurry is obtained.

[0098] S4. Heat the piezoelectric ceramic slurry in a water bath at 50-100℃, transfer it to a syringe for degassing, and then place it on the printing platform. The printing platform incorporates a 3D printing heated bed and a syringe heating device. Set the printing speed to 30mm / s, printing height to 2mm, layer thickness to 0.5mm, printing size to 30×30×1mm, fill rate to 50%, and nozzle inner diameter to 0.6mm. The printed product image is shown below. Figure 1 As shown in (d);

[0099] S5. Debinding and Sintering: The printed sample is first dried in an oven at 60℃ for 12 hours, and then debinding is performed in three stages. First, the temperature is increased to 200℃ at 0.6℃ / min and held for 1 hour to remove free water, crystal water and other moisture from the green body. Second, the temperature is increased to 500℃ at 0.7℃ / min and held for 2 hours to decompose and volatilize the organic matter in the green body. Third, the temperature is increased to 780℃ at 0.7℃ / min and held for 2 hours to increase the density. After debinding, the sample is heated to 1000℃ in a muffle furnace at a rate of 5℃ / min, and then increased to 1250℃ at 2℃ / min and held for 2 hours.

[0100] S6. Sample Polarization: After sintering, the printed ceramic sample is encapsulated with wax. During the wax encapsulation process, the sample is first placed in a vacuum chamber and evacuated for 2 minutes, then molten wax is introduced for penetration to improve the pore sealing rate. During cooling, the temperature is first allowed to drop naturally to 40°C, followed by water cooling to reduce the shrinkage stress of the wax layer. Then, a layer of wax is ground off until the sample is exposed. One side is then brushed with silver, and the other side is brushed with silver in the same way to effectively prevent the positive and negative electrodes from connecting, facilitating polarization. The polarization treatment conditions are: a DC electric field is applied in a silicone oil bath with an electric field strength of 2kV / mm, a treatment temperature of 80°C, and a polarization time of 20 minutes.

[0101] Comparative Example 2

[0102] This comparative example provides a method for preparing piezoelectric ceramics based on direct-write 3D printing. Unlike Example 1, this comparative example uses a copper sheet for polarization. The specific preparation steps are as follows:

[0103] S1. The general structural formula for 0.25PZN–0.75PLZT piezoelectric ceramic powder is:

[0104] 0.25Pb(Zn1 / 3Nb2 / 3)O3–0.75Pb 0.06 La 0.04 (Zr 0.53 Ti 0.47Weigh out Pb3O4 (99%), Sb2O5 (99.95%), ZrO2 (99%), TiO2 (99%), Nb2O5 (99.99%), ZnO (99%), and La2O3 (99.95%), with Sb2O5 added at 0.5% of the total mass. Place the mixture in a polytetrafluoroethylene ball mill jar, using anhydrous ethanol as the medium. The weight ratio of anhydrous ethanol to powder is 2:1. Place the mixture in a planetary ball mill and mill for 12 hours. After milling, remove the slurry and dry it in an oven at 80°C. Then place it on an alumina crucible and heat it in a muffle furnace at a heating rate of 5°C / min to 800°C and hold it at that temperature for 3 hours to complete the first sintering.

[0105] S2. Place the pre-fired powder into a polytetrafluoroethylene ball mill jar and use anhydrous ethanol as the dispersion medium. The weight ratio of anhydrous ethanol to powder is 2:1. Use a planetary ball mill at 600 rpm for 12 hours. After removing the slurry, dry it in an oven at 80°C. The dried powder is 0.25PZN–0.75PLZT piezoelectric ceramic powder.

[0106] S3. Add 0.5g of dispersant to 20ml of deionized water, stir to dissolve, then add 70g of lead titanate-based piezoelectric ceramic powder. Stir magnetically and sonicate to allow the dispersant to adsorb onto the powder surface. Add 3g of the first-stage binder (polyvinyl alcohol PVA), stir to remove bubbles or stir under low shear, then add 2g of glycerin and continue stirring. Add 1g of the second-stage binder (microcapsule-coated epoxy resin, particle size 1–5μm), stir under low shear back mixing, then vacuum degas, and allow to stand to remove bubbles to obtain the piezoelectric ceramic slurry.

[0107] The specific preparation process of the microcapsule coating layer is as follows:

[0108] A 5% gelatin aqueous solution and a 1% chitosan acetate solution were mixed at a volume ratio of 3:1 and the pH was adjusted to 5.5 to form the wall material solution. A thermosetting low molecular weight resin was used as the core material oil phase and emulsified to form 3μm oil droplets. The temperature was gradually lowered under stirring and the pH was adjusted to 4.8 to initiate a re-coagulation reaction, which allowed the gelatin-chitosan to deposit on the surface of the oil droplets to form a film. Subsequently, glutaraldehyde solution was added dropwise for cross-linking and curing. The film was then centrifuged, washed, and freeze-dried to obtain epoxy resin microcapsules with a gelatin-chitosan shell.

[0109] S4. Heat the piezoelectric ceramic slurry in a water bath at 50-100℃, transfer it to a syringe for degassing, and then place it on the printing platform. The printing platform incorporates a 3D printing heated bed and a syringe heating device. Set the printing speed to 30mm / s, printing height to 2mm, layer thickness to 0.5mm, printing size to 30×30×1mm, fill rate to 50%, and nozzle inner diameter to 0.6mm. The printed product image is shown below. Figure 1 As shown in (e);

[0110] S5. Debinding and Sintering: The printed sample is first dried in an oven at 60℃ for 12 hours, and then debinding is performed in three stages. First, the temperature is increased to 200℃ at 0.6℃ / min and held for 1 hour to remove free water, crystal water and other moisture from the green body. Second, the temperature is increased to 500℃ at 0.7℃ / min and held for 2 hours to decompose and volatilize the organic matter in the green body. Third, the temperature is increased to 780℃ at 0.7℃ / min and held for 2 hours to increase the density. After debinding, the sample is heated to 1000℃ in a muffle furnace at a rate of 5℃ / min, and then increased to 1250℃ at 2℃ / min and held for 2 hours.

[0111] S6. Sample Polarization: After sintering, the printed ceramic sample is encapsulated with wax. During the wax encapsulation process, the sample is first placed in a vacuum chamber and evacuated for 2 minutes, then molten wax is introduced for penetration to improve the pore sealing rate. During cooling, the temperature is first allowed to drop naturally to 40°C, followed by water cooling to reduce the shrinkage stress of the wax layer. Then, a layer of wax is ground off until the sample is exposed. One side is then brushed with silver, and the other side is brushed with silver in the same way to effectively prevent the positive and negative electrodes from connecting, facilitating polarization. The polarization treatment conditions are: a DC electric field is applied in a silicone oil bath with an electric field strength of 2kV / mm, a treatment temperature of 80°C, and a polarization time of 20 minutes.

[0112] Comparative Example 3

[0113] This comparative example provides a method for preparing piezoelectric ceramics based on direct-write molding 3D printing. Unlike Example 1, the ceramic sample in this comparative example is not encapsulated with wax; instead, silver is directly brushed onto both surfaces for polarization. The specific preparation steps are as follows:

[0114] S1. The general structural formula for 0.25PZN–0.75PLZT piezoelectric ceramic powder is:

[0115] 0.25Pb(Zn1 / 3Nb2 / 3)O3–0.75Pb 0.06 La 0.04 (Zr 0.53 Ti 0.47 Weigh out Pb3O4 (99%), Sb2O5 (99.95%), ZrO2 (99%), TiO2 (99%), Nb2O5 (99.99%), ZnO (99%), and La2O3 (99.95%), with Sb2O5 added at 0.5% of the total mass. Place the mixture in a polytetrafluoroethylene ball mill jar, using anhydrous ethanol as the medium. The weight ratio of anhydrous ethanol to powder is 2:1. Place the mixture in a planetary ball mill and mill for 12 hours. After milling, remove the slurry and dry it in an oven at 80°C. Then place it on an alumina crucible and heat it in a muffle furnace at a heating rate of 5°C / min to 800°C and hold it at that temperature for 3 hours to complete the first sintering.

[0116] S2. Place the pre-fired powder into a polytetrafluoroethylene ball mill jar and use anhydrous ethanol as the dispersion medium. The weight ratio of anhydrous ethanol to powder is 2:1. Use a planetary ball mill at 600 rpm for 12 hours. After removing the slurry, dry it in an oven at 80°C. The dried powder is 0.25PZN–0.75PLZT piezoelectric ceramic powder.

[0117] S3. Add 0.5g of dispersant to 20ml of deionized water, stir to dissolve, then add 70g of lead titanate-based piezoelectric ceramic powder. Stir magnetically and sonicate to allow the dispersant to adsorb onto the powder surface. Add 3g of the first-stage binder (polyvinyl alcohol PVA), stir to remove bubbles or stir under low shear, then add 2g of glycerin and continue stirring. Add 1g of the second-stage binder (microcapsule-coated epoxy resin, particle size 1–5μm), stir under low shear back mixing, then vacuum degas, and allow to stand to remove bubbles to obtain the piezoelectric ceramic slurry.

[0118] The specific preparation process of the microcapsule coating layer is as follows:

[0119] A 5% gelatin aqueous solution and a 1% chitosan acetate solution were mixed at a volume ratio of 3:1 and the pH was adjusted to 5.5 to form the wall material solution. A thermosetting low molecular weight resin was used as the core material oil phase and emulsified to form 3μm oil droplets. The temperature was gradually lowered under stirring and the pH was adjusted to 4.8 to initiate a re-coagulation reaction, which allowed the gelatin-chitosan to deposit on the surface of the oil droplets to form a film. Subsequently, glutaraldehyde solution was added dropwise for cross-linking and curing. The film was then centrifuged, washed, and freeze-dried to obtain epoxy resin microcapsules with a gelatin-chitosan shell.

[0120] S4. Heat the piezoelectric ceramic slurry in a water bath at 50-100℃, transfer it to a syringe for degassing, and then place it on the printing platform. The printing platform incorporates a 3D printing heated bed and a syringe heating device. Set the printing speed to 30mm / s, printing height to 2mm, layer thickness to 0.5mm, printing size to 30×30×1mm, fill rate to 50%, and nozzle inner diameter to 0.6mm. The printed product image is shown below. Figure 1 As shown in (f);

[0121] S5. Debinding and Sintering: The printed sample is first dried in an oven at 60℃ for 12 hours, and then debinding is performed in three stages. First, the temperature is increased to 200℃ at 0.6℃ / min and held for 1 hour to remove free water, crystal water and other moisture from the green body. Second, the temperature is increased to 500℃ at 0.7℃ / min and held for 2 hours to decompose and volatilize the organic matter in the green body. Third, the temperature is increased to 780℃ at 0.7℃ / min and held for 2 hours to increase the density. After debinding, the sample is heated to 1000℃ in a muffle furnace at a rate of 5℃ / min, and then increased to 1250℃ at 2℃ / min and held for 2 hours.

[0122] S6. Sample Polarization: After sintering, the printed ceramic sample is encapsulated with wax. During the wax encapsulation process, the sample is first placed in a vacuum chamber and evacuated for 2 minutes, then molten wax is introduced for penetration to improve the pore sealing rate. During cooling, the temperature is first allowed to drop naturally to 40°C, followed by water cooling to reduce the shrinkage stress of the wax layer. Then, a layer of wax is ground off until the sample is exposed. One side is then brushed with silver, and the other side is brushed with silver in the same way to effectively prevent the positive and negative electrodes from connecting, facilitating polarization. The polarization treatment conditions are: a DC electric field is applied in a silicone oil bath with an electric field strength of 2kV / mm, a treatment temperature of 80°C, and a polarization time of 20 minutes.

[0123] like Figure 1 As shown in the images of the printed samples prepared according to the methods of Examples 1-3 and Comparative Examples 1-3, it can be seen that the slurry prepared by the methods of Examples 1-3 can perfectly balance fluidity and formability, and the binder effectively suppresses the collapse caused by gravity flow, improving the interlayer bonding strength. However, Comparative Example 1 did not introduce a two-stage binder, resulting in edge collapse and poor interlayer bonding in the sample, and the forming quality was significantly insufficient. Although a two-stage binder was introduced in Comparative Examples 2 and 3, the sample surface was more dense and smooth, and the interlayer bonding was strong. However, Comparative Example 2 introduced copper sheets to prepare electrode polarization, and the piezoelectricity obtained was only about 100 pC / N. Comparative Example 3 directly brushed silver to connect the positive and negative electrodes, and the polarization failed. In addition, by setting parameters through slicing software to trigger the shear thinning effect, stable extrusion was achieved. The slicing software used was Simplify 3D.

[0124] The specific key parameters of Examples 1-3 and Comparative Examples 1-3 are shown in Table 1.

[0125] Table 1

[0126]

[0127]

[0128] The longitudinal piezoelectric constant (d) of the piezoelectric ceramic devices prepared in Examples 1-3 and Comparative Examples 1-3 was measured at room temperature using a quasi-static piezoelectric constant tester (ZJ-6A). 33 The results are shown in Table 2.

[0129] Table 2

[0130] sample Electric field (kV) Oil bath temperature (°C) Time (min) <![CDATA[d 33 (pC / N)]]> Sintering temperature (°C) Example 1 2kV 80 20min 466pC / N 1250℃ Example 2 2kV 80 20min 456pC / N 1250℃ Example 3 2kV 80 20min 495pC / N 1250℃ Comparative Example 1 2kV 80 20min 306pC / N 1250℃ Comparative Example 2 2kV 80 20min 102pC / N 1250℃ Comparative Example 3 2kV 80 20min Polarization failure 1250℃

[0131] As can be seen from Table 2, the devices prepared in Examples 1 to 3 of this invention all have good piezoelectric properties; Comparative Example 1, without the introduction of the two-stage bonding system, has a piezoelectricity of only about 300 pC / N; Comparative Example 2, by introducing copper sheets to prepare electrode polarization, has a piezoelectricity of only about 100 pC / N; Comparative Example 3, by directly brushing silver to connect the positive and negative electrodes, has failed to polarize; This proves that the devices prepared by the method of this application have better piezoelectric properties.

[0132] Finally, it should be noted that the specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. It is obvious to those skilled in the art that this application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this application is defined by the appended claims rather than the foregoing description, and therefore all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within this application.

Claims

1. A method for preparing 3D-printed piezoelectric ceramics, characterized in that, Includes the following steps: Three-dimensional printing was performed on piezoelectric ceramic slurry to obtain a porous piezoelectric ceramic preform with a complex structure. After drying, degreasing and sintering, porous piezoelectric ceramics are obtained. The sintered ceramic is first wax-sealed, and then conductive silver paste is brushed onto its surface to form electrodes. Piezoelectric ceramics are placed in silicone oil and polarized by applying an electric field to obtain 3D printed piezoelectric ceramics. The piezoelectric ceramic slurry is composed of the following components by mass percentage: 65wt%~75wt% lead zirconate titanate-based piezoelectric ceramic powder, 0.5wt%~1.0wt% dispersant, 2wt%~5wt% glycerol, 2wt%~4wt% first-stage binder, 1wt%~3wt% second-stage binder, and the balance being deionized water. The first-stage binder comprises a water-soluble thermoplastic polymer, and the second-stage binder comprises a microcapsule-encapsulated thermosetting low-molecular-weight resin, wherein the microcapsule coating layer is composed of a soluble gelatin and chitosan composite.

2. The method for preparing a 3D printed piezoelectric ceramic according to claim 1, characterized in that, The wax sealing process uses molten single paraffin wax, microcrystalline wax, or a mixture thereof. The porous piezoelectric ceramic is placed in the molten wax, and the molten wax is penetrated into the pores using a vacuum wax infiltration or stepwise pressure wax infiltration method. After cooling and solidification, the surface of the porous piezoelectric ceramic is exposed for silvering.

3. The method for preparing 3D printed piezoelectric ceramics according to claim 1, characterized in that, In the preparation of porous piezoelectric ceramic preforms, a direct writing molding method is used to perform three-dimensional printing of the piezoelectric ceramic slurry.

4. The method for preparing a 3D printed piezoelectric ceramic according to claim 1, characterized in that, The preparation method of the piezoelectric ceramic slurry includes the following steps: Add a dispersant to deionized water, stir to dissolve, then add lead zirconate titanate-based piezoelectric ceramic powder, stir magnetically, and perform ultrasonic treatment to allow the dispersant to be adsorbed on the surface of the lead zirconate titanate-based piezoelectric ceramic powder. Add the first-stage binder, degas and stir or stir at low shear, then add glycerin and continue stirring; After adding a second-stage binder, low-shear back mixing, vacuum degassing, and standing to remove bubbles, piezoelectric ceramic slurry is obtained.

5. The method for preparing a 3D printed piezoelectric ceramic according to claim 1, characterized in that, The lead zirconate titanate-based piezoelectric ceramic powder is... Based on, doped with 0.5wt% The resulting powder.

6. The method for preparing a 3D-printed piezoelectric ceramic according to claim 1, characterized in that, The piezoelectric ceramic paste is heated in a water bath at 50°C to 100°C and degassed before printing.

7. A 3D-printed piezoelectric ceramic, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 6.

8. An electronic device, characterized in that, Including the 3D printed piezoelectric ceramic as described in claim 7.

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