Vibration device for enhancing the strength and plasticity of laser additive manufacturing alloys using multilayer piezoelectric ceramics

Abstract

This invention discloses a multilayer piezoelectric ceramic vibration device for improving the strength and plasticity of alloys manufactured by laser additive manufacturing. Belonging to the field of electrical ceramic materials technology, it includes a vibration platform, a function amplifier, a power amplifier, and a multilayer piezoelectric ceramic actuator adapted to the vibration platform. The vibration platform supports a metal substrate and transmits the vibration of the multilayer piezoelectric ceramic actuator to the molten pool during the laser additive manufacturing process. Through the high-frequency stable vibration output by the multilayer piezoelectric ceramic actuator, a strong acoustic flow effect and mechanical disturbance effect are formed in the molten pool region. On the one hand, this accelerates the escape of gas from the molten pool, completely eliminating porosity defects such as pores and shrinkage, solving the problems of incomplete fusion and uneven interface bonding in traditional laser additive manufacturing. On the other hand, it breaks up the coarse dendrites growing in the molten pool, increases the nucleation core, and achieves significant refinement of grains and the second phase structure, ultimately achieving a synergistic improvement in alloy strength and plasticity.

Description

Technical Field

[0001] This invention belongs to the field of electrical ceramic materials technology, specifically relating to a multilayer piezoelectric ceramic vibration device for improving the strength and plasticity of laser additive manufacturing alloys. Background Technology

[0002] Metal melting and forming technology, as a core process in aerospace, high-end equipment manufacturing and other fields, plays an irreplaceable role in the forming, connection and repair of structural parts by heating and melting metals to achieve alloying or metallurgical bonding. However, this technology inevitably forms a large temperature gradient during rapid solidification. This inherent characteristic makes it easy for metallurgical defects such as coarse columnar / dendritic crystals, compositional segregation, microcracks and porosity to be generated inside the formed parts. These defects will seriously disrupt the continuity of the internal structure of the material, significantly reduce the key mechanical properties of the workpiece such as strength, plasticity and wear resistance, and even affect its service safety and service life. This has become the core bottleneck restricting the development of metal melting and forming technology towards high-end and precision. The industry generally adopts the method of applying external physical fields to control the solidification structure. Among them, piezoelectric ceramic ultrasonic vibration has become a research hotspot due to its unique advantages.

[0003] Existing ultrasonic vibration devices have many technical defects and are difficult to meet the needs of practical applications: First, the driving unit is mostly a resonant piezoelectric ceramic transducer, which requires the amplitude to be amplified by an amplitude transformer, resulting in a large size and complex structure of the device, which cannot be compactly integrated with laser additive manufacturing equipment and has poor adaptability; Second, traditional transducers are made up of several piezoelectric ceramics stacked together, with low thrust density. Under the constraint of the platform support, the vibration energy is severely lost and the amplitude decays sharply, making it difficult to form an effective effect on the molten pool. Summary of the Invention

[0004] The purpose of this invention is to provide a multilayer piezoelectric ceramic vibration device that enhances the strength and plasticity of laser additive manufacturing alloys, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a multilayer piezoelectric ceramic vibration device for improving the strength and plasticity of laser additive manufacturing alloys, comprising a vibration platform, a function amplifier and a power amplifier, and a multilayer piezoelectric ceramic actuator adapted to the vibration platform. The vibration platform is used to support a metal substrate and transmit the vibration of the multilayer piezoelectric ceramic actuator to the molten pool in the laser additive manufacturing process. The multilayer piezoelectric ceramic actuator is integrally formed by alternating stacking and co-firing of multiple layers of piezoelectric ceramic sheets and internal electrodes. The vibration platform includes, from top to bottom, an upper platform panel, a heat-insulating support, an upper base plate, a spring column, and a lower base plate. The laminated piezoelectric ceramic actuator is disposed between the upper base plate and the lower base plate and is fixed and stacked to a specified height by high-temperature resistant adhesive. The laminated piezoelectric ceramic actuator is welded with copper wires to connect to the drive circuit. The function amplifier and the power amplifier are electrically connected, and the power amplifier is electrically connected to the copper wires of the multilayer piezoelectric ceramic actuator.

[0006] In a preferred embodiment, the vibration platform is assembled in a laser additive manufacturing equipment, specifically located below the laser head. The laser additive manufacturing equipment includes a laser generator, a laser reflector, a focusing lens, and an inert gas protective chamber. The metal substrate is fixed to the upper panel of the vibration platform, and the vibration platform is located inside the inert gas protective chamber.

[0007] This invention also discloses a process for preparing piezoelectric ceramic sheets, including the following steps: S1. Raw material weighing: Weigh Pb3O4, ZrO2, TiO2, Nb2O5, ZnO, Li2CO3, MnO2 and Sm2O3. The powder purity is ≥99.5%, the particle size is ≤10μm, and the weighing accuracy is 0.1mg. S2. First ball milling: Mix the weighed powder with alcohol in a nylon ball mill jar and ball mill in a planetary ball mill at 300 rpm for 24 hours. After drying, sieve through a 300-mesh screen to form a mixed raw material. S3. Pre-calcination: Place the sieved mixed raw materials in a muffle furnace at 880℃ and pre-calcine for 8 hours; S4. Second ball milling: Mix the pre-calcined powder with alcohol, ball mill again for 24 hours, dry and sieve through a 100-mesh sieve; S5. Slurry preparation: The ceramic powder after the second ball milling is mixed with an organic solvent and ball milled on a drum ball mill for 24 hours to prepare a casting slurry. The organic solvent is composed of 30wt.% ethanol + methyl ethyl ketone, 7wt% polyvinyl alcohol, 1wt% tributyl phosphate and 7wt% PVA. S6. Casting: After vacuum degassing the casting slurry, cast it on a casting machine. Adjust the relative height between the doctor blade and the PET film to 120μm, and the casting speed to 1.2m / min. Dry at 100℃. S7. Electrode printing: Print Ag-20wt%Pd electrodes on the surface of the dried green body, and then separate the film from the PET film. S8. Stacking and pressing: The films with electrodes are stacked sequentially according to the interdigitated electrode sequence using a stacking machine. The offset of the interdigitated electrodes is 300μm, and the error does not exceed 100μm. The stacked films are then pressed into shape in an isostatic press with a pressure of 100MPa. S9. Cutting: Use a wire cutting machine to cut the pressed multilayer film into small pieces of 8×8×4mm3 according to the electrode arrangement; S10, Low-temperature co-firing: Heat to 600℃ at a heating rate of 0.5℃ / min, hold for 2 hours to remove the glue, then heat to 980℃ at a heating rate of 0.5℃ / min, hold for 4 hours, and finally cool to room temperature at a cooling rate of 0.5℃ / min. S11. Subsequent processing: The edges of the fired multilayer piezoelectric ceramic are ground flat and chamfered. External electrodes are screen-printed on the side. After the electrodes are dried, they are placed in silicone oil at 90°C and polarized under an electric field of 2.5kV / mm. S12. Screening and Assembly: Test the displacement, impedance, loss, and leakage current electrical performance parameters of the multilayer ceramics, screen out the piezoelectric ceramics that meet the requirements, stack the multilayer units to the specified height using high-temperature resistant adhesive and solder copper wires on them, and test the electrical performance again.

[0008] In a preferred embodiment, all internal structural components of the vibration platform are made of 304L stainless steel.

[0009] In a preferred embodiment, the components of the vibration platform are connected by threaded connections.

[0010] In a preferred embodiment, the composite piezoelectric ceramic actuator has the general formula xPb(Zr,Ti)O3-(1-x)Pb(Nb,Zn)O3-amol%Li2CO3-bmol%MnO2-cmol%Sm2O3, where 0≤x≤0.9, 0.2≤a≤0.6, 0≤b≤0.4, and 0.2≤c≤0.4.

[0011] In a preferred embodiment, the optimal composition of the multilayer piezoelectric ceramic actuator is 0.7Pb(Zr,Ti)O3-0.3Pb(Nb,Zn)O3-0.5mol%Li2CO3-0.2mol%MnO2-0.2mol%Sm2O3.

[0012] In a preferred embodiment, the perovskite lattice of the multilayer piezoelectric ceramic actuator is composed of three phases: tetragonal, trigonal, and pseudocubic, with few internal pores and defects, sufficient grain growth, and straight and continuous internal electrodes.

[0013] In a preferred embodiment, the function amplifier regulates the frequency and voltage of the electric field applied to the multilayer piezoelectric ceramic actuator through a power amplifier, thereby achieving precise control of the amplitude and frequency of the vibration platform, with a frequency regulation range not exceeding 800Hz.

[0014] In a preferred embodiment, a storage component is connected to the outside of the inert gas protection box, the storage component being used to transport metal powder and inert gas.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This device provides a multilayer piezoelectric ceramic vibration device to enhance the strength and plasticity of alloys manufactured by laser additive manufacturing. Through high-frequency stable vibration output from the multilayer piezoelectric ceramic actuator, a strong acoustic flow effect and mechanical disturbance effect are generated in the molten pool region. On the one hand, it accelerates the escape of gas in the molten pool, completely eliminating porosity defects such as gas pores and shrinkage, and solving the problems of incomplete fusion and uneven interface bonding in traditional laser additive manufacturing. On the other hand, it breaks up the coarse dendrites growing in the molten pool, increases the nucleation core, and achieves significant refinement of grains and second phase structure, ultimately achieving a synergistic improvement in alloy strength and plasticity.

[0016] This invention provides a multilayer piezoelectric ceramic vibration device to enhance the strength and plasticity of alloys manufactured by laser additive manufacturing. The multilayer piezoelectric ceramic actuator adopts a three-phase coexisting perovskite structure and optimized composition ratio, achieving a stable displacement of 27μm at 120V with low hysteresis. The heating temperature is only 110℃ under 800Hz high-frequency drive, and it still has long-term stability under no heat dissipation conditions. Through a control system composed of a function amplifier and a power amplifier, precise control of frequency from 0-800Hz and amplitude from 0-27μm is achieved, avoiding the vibration instability problem of traditional devices and meeting the control requirements of different molten pools.

[0017] This device provides a multilayer piezoelectric ceramic vibration device to enhance the strength and plasticity of laser additive manufacturing alloys. The piezoelectric ceramic sheet preparation process involves multiple rigorous steps, including two ball milling processes, precise pre-firing, low-temperature co-firing, and polarization activation. Each process parameter is quantitatively controlled to ensure that the product has uniform composition, dense structure, and stable electrical performance. Through dual performance screening, unqualified products are eliminated, ensuring that the performance consistency error of the multilayer piezoelectric ceramic actuator is ≤5%, providing a core guarantee for the stable operation of the device.

[0018] This multilayer piezoelectric ceramic vibration device enhances the strength and plasticity of laser additive manufacturing alloys. Through the acoustic flow effect and mechanical disturbance effect of high-frequency vibration, it accelerates the escape of molten pool gas, breaks up coarse dendrites, reduces the porosity of the alloy (coating), basically eliminates defects such as incomplete fusion and cracks, and makes the interface bonding more continuous and smooth, significantly improving the integrity and reliability of the internal structure of the material.

[0019] This multilayer piezoelectric ceramic vibration device enhances the strength and plasticity of laser additive manufacturing alloys. It refines grain size (equiaxed grain size reduced by 60%) and achieves uniform dispersion of the second phase, increasing the number of grain boundaries and effectively hindering dislocation movement. This results in a synergistic optimization of strength and plasticity, increasing the hardness of Stellite 3 alloy coatings by over 35%, and improving CoCrNiTi... 0.3 The tensile strength and elongation of the medium-entropy alloy are improved simultaneously, solving the key problem of the "strength-ductility contradiction" in traditional additive manufacturing alloys. Attached Figure Description

[0020] Figure 1This is a front view of the structure of the multilayer piezoelectric ceramic vibration device for improving the strength and plasticity of laser additive manufacturing alloys according to the present invention. Figure 2 This is a front view of the vibration platform structure of the present invention; Figure 3 This is a schematic diagram of the XRD pattern of the piezoelectric ceramic of the present invention; Figure 4 This is a schematic diagram of the microstructure of the piezoelectric ceramic monolayer of the present invention.

[0021] Figure 5 This is a schematic diagram of the electrode morphology of the multilayer piezoelectric ceramic of the present invention.

[0022] Figure 6 This is another schematic diagram of the electrode morphology of the multilayer piezoelectric ceramic of the present invention.

[0023] Figure 7 The present invention is 7×7×36mm 3 A schematic diagram of the electro-displacement curve of a multilayer piezoelectric ceramic.

[0024] Figure 8 This is a schematic diagram of the heating curves of the laminated ceramic of the present invention under different vibration frequencies and a driving voltage of 120V.

[0025] Figure 9 This is a schematic diagram showing the macroscopic morphology, microstructure, and hardness of the Stellite 3 alloy coating assisted by the vibration field laser cladding of the present invention.

[0026] Figure 10 This invention relates to vibration-free field-assisted laser additive manufacturing of CoCrNiTi. 0.3 A schematic diagram comparing the microstructure and tensile properties of medium-entropy alloys.

[0027] In the diagram: 1. Vibration platform; 101. Lower base plate; 102. Upper base plate; 103. Spring column; 104. Laminated piezoelectric ceramic actuator; 2. Inert gas protection box; 3. Power amplifier; 4. Function amplifier; 5. Laser generator; 6. Laser reflector; 7. Focusing lens; 8. Storage component. Detailed Implementation

[0028] The present invention will be further described below with reference to embodiments.

[0029] The following embodiments are used to illustrate the present invention, but should not be used to limit the scope of protection of the present invention. The conditions in the embodiments can be further adjusted according to specific conditions, and simple improvements to the method of the present invention under the premise of the concept of the present invention are all within the scope of protection claimed by the present invention.

[0030] Please see Figures 1-10The present invention provides a multilayer piezoelectric ceramic vibration device for improving the strength and plasticity of laser additive manufacturing alloys. It comprises a vibration platform 1, a drive control system including a function amplifier 4, a power amplifier 3, a multilayer piezoelectric ceramic actuator 104, and supporting laser additive manufacturing equipment components. The components work together to achieve precise coupling between the vibration field and the laser additive manufacturing process.

[0031] The vibration platform 1 adopts a layered design from top to bottom, comprising an upper platform panel, heat insulation supports, an upper base plate 102, spring columns 103, and a lower base plate 101. The upper platform panel, as the bearing surface of the metal substrate, must possess high flatness and rigidity to ensure uniform transmission of vibration energy. The heat insulation supports are made of high-temperature resistant heat insulation material, effectively preventing the high temperature of the molten pool during laser additive manufacturing from being conducted to the piezoelectric ceramic actuator below, thus avoiding performance degradation due to high temperatures. The spring columns 103 are evenly distributed between the upper base plate 102 and the lower base plate 101, serving as buffers and guides to ensure consistent vibration direction and reduce lateral vibration interference. The lower base plate 101, as the supporting foundation of the entire platform, is fixedly connected to the worktable of the laser additive manufacturing equipment to ensure stability during vibration.

[0032] All internal structural components of the platform are made of 304L stainless steel, which has excellent mechanical strength, high temperature resistance and corrosion resistance, and can adapt to the harsh working environment of laser additive manufacturing. The components are connected by high-precision threaded joints, which ensures high assembly accuracy and a stable structure, effectively preventing loosening or displacement during vibration and ensuring efficient transmission of vibration energy.

[0033] The overall dimensions of the platform are 200×200×150mm. 3 Compared to traditional ultrasonic vibration platforms with amplitude transformers, this device reduces volume by more than 60%, has a compact structure, and can be directly embedded into the working area of ​​existing laser additive manufacturing equipment. It achieves seamless integration with components such as the laser head and inert gas protective box, without requiring large-scale modifications to the original equipment.

[0034] The multilayer piezoelectric ceramic actuator 104 serves as the core vibration source and is located in the central area between the upper base plate 102 and the lower base plate 101. It is fixed by curing with high-temperature resistant adhesive and stacked to a specified height according to vibration requirements. High-conductivity copper wires are welded to both ends of the actuator for connecting to the drive circuit to ensure stable transmission of electrical signals.

[0035] The process employs an integrated molding technique that involves alternating lamination and co-firing of multilayer piezoelectric ceramic sheets and internal electrodes. The number of layers is designed according to displacement requirements, and each piezoelectric ceramic sheet has a uniform thickness. The internal electrodes are tightly bonded to the ceramic sheets without obvious interface defects. The overall structure is dense, achieving a compact size of 7×7×36mm. 3 It has an ultra-high thrust density, which can effectively overcome the restraint effect of the platform support and ensure stable amplitude output.

[0036] The piezoelectric ceramic composition of the actuator is designed with precise proportions: xPb(Zr,Ti)O3-(1-x)Pb(Nb,Zn)O3-amol%Li2CO3-bmol%MnO2-cmol%Sm2O3, where 0≤x≤0.9, 0.2≤a≤0.6, 0≤b≤0.4, and 0.2≤c≤0.4.

[0037] By introducing Nb and Zn elements to optimize the piezoelectric properties of the perovskite structure, adding Li2CO3 to lower the sintering temperature and improve sintering density, MnO2 to refine the grains and improve mechanical properties, and Sm2O3 to regulate the crystal structure and enhance the piezoelectric response.

[0038] Extensive experimental verification has shown that the optimal ingredient ratio is: The optimal overall performance of piezoelectric ceramics is achieved with the following composition: 0.7Pb(Zr,Ti)O3-0.3Pb(Nb,Zn)O3-0.5mol%Li2CO3-0.2mol%MnO2-0.2mol%Sm2O3.

[0039] The piezoelectric ceramic is mainly composed of a single perovskite structure. XRD pattern analysis and fitting of the 45° characteristic angle diffraction peaks reveal that the perovskite lattice exhibits a coexistence of three phases: tetragonal P4mm, trigonal R3m, and pseudocubic C1m. This three-phase coexistence structure significantly reduces polarization resistance and improves piezoelectric response sensitivity, enabling the actuator to generate large displacements even at low voltages. Microstructural observation shows that the internal porosity defect rate of the ceramic is less than 1%, the grains are fully grown and uniform in size (average grain size ≤ 5 μm), and the internal electrodes are straight and continuous without breakage or detachment, ensuring the structural stability and electrical performance consistency of the actuator.

[0040] With a driving voltage of 120V, the maximum displacement can reach 27μm, and the displacement hysteresis rate is ≤5%, resulting in high motion accuracy. Under the driving conditions of 120V voltage and 800Hz high frequency, the heating temperature after 2 hours of continuous operation is only 110℃, which is much lower than the heating temperature of traditional piezoelectric transducers (≥200℃). It still has excellent frequency stability in the absence of additional heat dissipation devices and in a vacuum environment, which can meet the requirements of long-term continuous operation. The optimal vibration parameters are 120V voltage and 200Hz frequency. Under these parameters, the vibration energy transfer efficiency is the highest, and the control effect on the molten pool is optimal.

[0041] The drive control system consists of a function amplifier 4 and a power amplifier 3. The function amplifier 4 and the power amplifier 3 are electrically connected through shielded wires. The output terminal of the power amplifier 3 is electrically connected to the copper wire of the laminated piezoelectric ceramic actuator 104, forming a complete drive circuit.

[0042] The function amplifier 4 can accurately output various waveform signals such as sine waves and square waves in the range of 0-800Hz, with a frequency adjustment accuracy of ±1Hz and a voltage adjustment range of 0-120V. It can flexibly set the vibration frequency and voltage parameters according to the additive manufacturing requirements of different alloy materials. The power amplifier 3 amplifies the weak electrical signal output by the function amplifier to ensure that the output signal has sufficient driving capability to drive the laminated piezoelectric ceramic actuator 104 to generate stable vibration. It also has overcurrent and overvoltage protection functions to prevent the actuator from being damaged due to circuit failure. Through this control system, precise closed-loop control of the amplitude and frequency of the vibration platform 1 can be achieved, with an amplitude adjustment range of 0-27μm to meet the needs of different molten pool control scenarios.

[0043] The vibration platform 1 is assembled inside the inert gas protective box 2 of the laser additive manufacturing equipment. Its specific position is set directly below the laser head. The vertical distance between it and the laser head can be adjusted according to the processing requirements, usually 50-100mm, to ensure that the laser focus can accurately act on the molten pool area on the surface of the metal substrate.

[0044] The laser additive manufacturing equipment includes a laser generator 5, a laser reflector 6, a focusing lens 7, an inert gas protective box 2, and a storage component 8.

[0045] The laser beam generated by laser generator 5 is reflected by laser reflector 6 and focused by focusing lens 7, then vertically irradiates the surface of the metal substrate on vibration platform 1, forming a molten pool; storage component 8 is connected to inert gas protection box 2, on the one hand conveying metal powder such as Stellite 3 alloy powder, CoCrNiTi to the processing area. 0.3 On the one hand, medium-entropy alloy powder, etc., are continuously supplied, and on the other hand, inert gases such as argon are continuously supplied to form a protective atmosphere to prevent the molten metal from oxidizing at high temperatures; the metal substrate is fixed to the upper plate of the vibration platform 1 by a clamp to ensure that there is no relative displacement between the substrate and the platform during vibration, and the vibration energy can be efficiently transferred to the molten pool.

[0046] In this invention, the piezoelectric ceramic sheet serves as the core unit of the multilayer piezoelectric ceramic actuator. Its fabrication process directly determines the actuator's performance. The specific steps are as follows, with each step involving strict control of process parameters to ensure product quality: S1. Raw Material Pretreatment and Weighing: High-purity raw materials are selected: Pb3O4, ZrO2, TiO2, Nb2O5, ZnO, Li2CO3, MnO2, and Sm2O3 are weighed, with a powder purity ≥99.5%, particle size ≤10μm, and weighing accuracy of 0.1mg. A laser particle size analyzer is used to ensure uniform particle size distribution, avoiding the impact of impurities or excessively large particle sizes on ceramic performance. Precise weighing: Based on the target component's general formula: 0.7Pb(Zr,Ti)O3-0.3Pb(Nb,Zn)O3-0.5mol%Li2CO3-0.2mol%MnO2-0.2mol%Sm2O3 were weighed using an electronic balance with a weighing accuracy of 0.1mg to ensure that the proportions of each component were accurate with an error ≤±0.05%.

[0047] S2. First ball milling (mixing and dispersing): Mix all the weighed raw material powders with anhydrous ethanol at a mass ratio of 1:1.5, pour into a nylon ball mill jar, use zirconia balls as the milling medium, and the ball-to-material ratio is 5:1.

[0048] The grinding jar is installed on a planetary ball mill, the rotation speed is set to 300 rpm, and the grinding time is 24 hours. Through mechanical collision and grinding, the raw material powder is uniformly mixed and initially refined.

[0049] After ball milling, the slurry is placed in an 80°C forced-air drying oven for 12 hours to remove the ethanol solvent. Then, it is sieved through a 300-mesh standard sieve to remove incompletely dispersed agglomerated particles, resulting in a uniformly mixed powder raw material.

[0050] S3. Pre-calcination (synthesis reaction): The sieved mixed raw materials are loaded into an alumina crucible and placed in a muffle furnace for pre-calcination.

[0051] The heating rate was set to 0.5℃ / min, and the temperature was raised to 880℃ and held for 8 hours. During this process, the raw materials underwent solid-phase reactions to generate precursors with perovskite structures, while volatile impurities such as adsorbed water and carbonate decomposition products in the raw materials were removed.

[0052] After pre-firing, the blocks are cooled to room temperature in the furnace and then removed for later use.

[0053] S4. Second ball milling (refining particle size): The pre-calcined block is crushed into powder, mixed with anhydrous ethanol at a mass ratio of 1:1.5, and poured into a nylon ball mill jar again. The same ball-to-material ratio and ball mill parameters as the first ball milling are used, and the ball mill is milled for 24 hours.

[0054] This step aims to further refine the powder particle size, ensuring uniform particle size and meeting the requirements for casting. After ball milling, the slurry is dried at 80°C for 12 hours and then sieved through a 100-mesh standard sieve to remove coarse particle impurities.

[0055] S5. Slurry preparation (precursor for casting): Prepare a composite organic solvent consisting of 30wt.% ethanol + methyl ethyl ketone (ethanol to methyl ethyl ketone volume ratio 1:1), 7wt% polyvinyl alcohol (binder), 1wt% tributyl phosphate (defoamer) and 7wt% PVA (plasticizer), mix evenly and set aside.

[0056] The ceramic powder after the second ball milling was mixed with the composite organic solvent at a mass ratio of 1:0.8, poured into a drum ball mill, and ball milled for 24 hours to fully disperse the powder in the organic solvent and form a uniform and stable cast slurry.

[0057] The viscosity of the slurry is controlled at 500-800 mPa·s (25℃) and tested by a rotational viscometer to ensure that it meets the requirements for casting.

[0058] S6. Casting (Preparation of green film): Pour the cast slurry into a vacuum degassing tank and degas for 30 minutes at a vacuum of -0.09MPa to remove air bubbles from the slurry and avoid pore defects in the green film.

[0059] The defoamed slurry is poured into the casting machine's trough. The relative height between the scraper and the PET film is adjusted to 120 μm. The casting speed is set to 1.2 m / min. The film is then dried in a 100°C drying channel to remove organic solvents and form a continuous ceramic green film.

[0060] The thickness of the green film is controlled at 100-120μm, with a thickness uniformity error of ≤±5μm. Multi-point detection using a thickness gauge ensures compliance with requirements.

[0061] S7. Electrode printing (preparation of internal electrodes): Using screen printing technology, Ag-20wt% Pd electrode paste is printed on the surface of the dried green film. The electrode pattern is made according to the design requirements of the interdigitated electrode, and the printing thickness is 10-15μm.

[0062] After printing, the film is placed in a 120°C forced-air drying oven for 30 minutes to cure the electrode paste. Then the film is separated from the PET film to obtain a green film with internal electrodes.

[0063] S8. Stacking and pressing (forming a multi-layer structure): Using an automatic stacking machine, green films with internal electrodes are stacked sequentially according to the order of interdigitated electrodes. The electrodes of adjacent films are staggered and aligned. The offset of the interdigitated electrodes is strictly controlled to 300μm, with an error not exceeding 100μm, to ensure uniform electric field distribution during subsequent polarization.

[0064] The stacked diaphragm preforms are placed in an isostatic press and pressed for 30 minutes at 100 MPa to improve the density of the preforms and reduce internal porosity.

[0065] S9. Cutting (Precise Dimensioning): Using a wire EDM machine, cut the dimensions of the laminated piezoelectric ceramic actuator according to its design dimensions (8×8×4mm). 3The pressed multilayer film blank is precisely cut according to the electrode arrangement, with a cutting accuracy of ±0.05mm, to ensure that the blank size meets the assembly requirements.

[0066] Deionized water is used for cooling during the cutting process to prevent the blank from cracking or the electrode from oxidizing due to high temperature.

[0067] S10, Low-temperature co-firing (densification and sintering combination): The cut green body is placed in the sintering furnace and a segmented heating process is adopted: First, the temperature is raised to 600℃ at a heating rate of 0.5℃ / min and held for 2 hours to remove the binder, remove the organic components such as binder and plasticizer in the green body. Nitrogen gas is introduced during the binder removal process to prevent oxidation of the green body. After the binder is removed, the temperature is increased to 980℃ at a rate of 0.5℃ / min and held for 4 hours to allow the green body to be fully sintered and dense, forming a stable perovskite structure and a good electrode-ceramic interface. After sintering, the temperature is reduced to room temperature at a rate of 0.5℃ / min to avoid thermal stress caused by excessively rapid cooling, which could lead to cracking of the green body.

[0068] S11. Subsequent processing (polarization activation and appearance finishing): Appearance finishing: The fired multilayer piezoelectric ceramic is edge-grinding and chamfering with a diamond grinding wheel to remove burrs and sharp edges, and to avoid stress concentration during use. After grinding, the ceramic dimensional accuracy is controlled to ±0.03mm.

[0069] External electrode preparation: Ag electrode paste was printed on the side of the ceramic using screen printing, and then dried at 150℃ for 30 min to cure the electrode.

[0070] Polarization treatment: The multilayer piezoelectric ceramic with external electrodes is immersed in silicone oil at 90°C, and a DC electric field of 2.5 kV / mm is applied for polarization for 30 min, so that the electric domains inside the ceramic are oriented along the direction of the electric field and the piezoelectric properties are activated; after polarization, the ceramic is taken out and naturally cooled to room temperature.

[0071] S12. Screening and Assembly (Ensuring Performance Consistency): Electrical Performance Testing: Using equipment such as piezoelectric performance testers and impedance analyzers, the electroinduced displacement, impedance, dielectric loss, leakage current, and other parameters of the laminated ceramics are tested. Products that meet the electrical performance requirements (displacement ≥ 25 μm @ 120V, dielectric loss ≤ 1%, leakage current ≤ 1 μA) are screened out, and unqualified products are rejected.

[0072] Assembly and molding: Using high-temperature resistant epoxy resin adhesive, the selected multilayer ceramic units are stacked to a specified height (36mm), and copper wires are welded as lead electrodes. After assembly, the electrical performance is tested again to ensure that the assembly process does not affect the performance, and finally the multilayer piezoelectric ceramic actuator 104 is obtained.

[0073] Application Example 1: Vibration Field Assisted Laser Cladding of Stellite 3 Alloy Coating like Figure 9 As shown, Stellite 3 alloy powder is a Co-Cr-WC alloy powder specifically designed for laser cladding. It possesses advantages such as excellent high-temperature wear resistance and superior thermal shock resistance, making it widely applicable in fields such as tool and die steel remanufacturing. Therefore, this experiment optimized the laser cladding process parameters, obtaining the optimal processing parameters as follows: laser power P = 1600 W, scanning speed v = 10 mm / s, and overlap rate 50%. The optimal vibration parameters for the piezoelectric actuator were: voltage 120 V and frequency 200 Hz. The figure below shows the effect of piezoelectric actuator-assisted vibration on the porosity, microstructure evolution, and hardness of the laser-clad Stellite 3 alloy coating. Without vibration, obvious porosity defects (black circular holes) exist inside the coating, the interface between the coating and the substrate is uneven, and there is a risk of localized incomplete fusion. The high-frequency vibration introduced by the piezoelectric actuator enhances the fluid flow within the molten pool through the acoustic flow effect, accelerating gas escape. The coating surface has no obvious porosity, and the interface between the coating and the substrate is more continuous and smooth, effectively reducing the risk of metallurgical defects.

[0074] Simultaneously, the high-frequency vibration of the piezoelectric actuator mechanically disturbs the molten pool, breaking up growing dendrites, increasing nucleation sites, and significantly refining the grains and carbides, resulting in a more uniform carbide distribution. The equiaxed grain size of the coating decreases by 60%. The coating hardness significantly increases from 420 HV to 590 HV, an increase of over 35%. The increased hardness is mainly due to the refined grains and carbides, which increase the number of grain boundaries, hindering dislocation movement, and the more uniform carbide distribution, which more effectively inhibits dislocation slip. Therefore, piezoelectric actuator-assisted laser cladding can provide comprehensive optimization in defect control, microstructure refinement, and mechanical property improvement.

[0075] Application Example 2: Vibration Field Assisted Laser Additive Manufacturing of CoCrNiTi 0.3 Medium entropy alloys CoCrNiTi 0.3Medium-entropy alloys, due to their abundant internal nano-L12 phase strengthening and the synergistic effect of strong plasticity through multiple deformation mechanisms, show promising application prospects in high-temperature extreme environments. Therefore, this experiment optimized the laser cladding process parameters, obtaining the optimal processing parameters as follows: laser power P = 1000 W, scanning speed v = 10 mm / s, overlap ratio 50%, and layer height 0.34 mm. The optimal vibration parameters for the piezoelectric actuator were: voltage 120 V and frequency 200 Hz.

[0076] Figure 10 For vibration-free laser additive manufacturing of CoCrNiTi 0.3 Comparison of microstructure and tensile properties of medium-entropy alloys Figure 10 From left to right, the graphs are: (a) no vibration field, (b) with vibration field, and (c) stretching curve. Figure 10 In Figures (a) and (b), the dashed lines represent the molten pool lines.

[0077] Figure (a) shows the microstructure of the alloy manufactured by vibration-free laser additive manufacturing. It contains a small number of circular pores, and the microstructure is mainly composed of relatively coarse columnar and equiaxed crystals.

[0078] Figure (b) shows the microstructure of the alloy manufactured by vibration field-assisted laser additive manufacturing. The number of micropores within the alloy is significantly reduced. The spacing and area of ​​the columnar crystals are both greatly decreased, and the size of the intergranular second phase is smaller and more dispersed. A comparison of the tensile properties of the two models shows that vibration field assistance can significantly and synergistically improve the strength and plasticity of the additively manufactured alloy.

[0079] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A vibratory device for enhancing the strength and plasticity of laminated piezoelectric ceramic alloys in laser additive manufacturing, characterized in that, The system includes a vibration platform (1), a function amplifier (4), a power amplifier (3), and a multilayer piezoelectric ceramic actuator (104) adapted to the vibration platform (1). The vibration platform (1) is used to support the metal substrate and transmit the vibration of the multilayer piezoelectric ceramic actuator (104) to the molten pool in the laser additive manufacturing process. The multilayer piezoelectric ceramic actuator (104) is integrally formed by alternating stacking and co-firing of multilayer piezoelectric ceramic sheets and internal electrodes. The vibration platform (1) includes, from top to bottom, an upper platform panel, a heat insulation support, an upper base plate (102), a spring column (103), and a lower base plate (101). The laminated piezoelectric ceramic actuator (104) is disposed between the upper base plate (102) and the lower base plate (101), and is fixed and stacked to a specified height by high-temperature resistant glue. The laminated piezoelectric ceramic actuator (104) is welded with copper wires to connect to the drive circuit. The function amplifier (4) and the power amplifier (3) are electrically connected, and the power amplifier (3) is electrically connected to the copper wire of the multilayer piezoelectric ceramic actuator (104).

2. The multilayer piezoelectric ceramic vibration device for improving the strength and plasticity of laser additive manufacturing alloys according to claim 1, characterized in that: The vibration platform (1) is assembled in the laser additive manufacturing equipment, specifically located below the laser head. The laser additive manufacturing equipment includes a laser generator (5), a laser reflector (6), a focusing lens (7), and an inert gas protection box (2). The metal substrate is fixed on the upper panel of the vibration platform (1), and the vibration platform (1) is located inside the inert gas protection box (2).

3. The preparation process of the piezoelectric ceramic sheet, characterized in that, The vibratory device for enhancing the strength and plasticity of laminated piezoelectric ceramics in laser additive manufacturing, as described in any one of claims 1-2, further includes the following steps: S1. Raw material weighing: Weigh Pb3O4, ZrO2, TiO2, Nb2O5, ZnO, Li2CO3, MnO2 and Sm2O3. The powder purity is ≥99.5%, the particle size is ≤10μm, and the weighing accuracy is 0.1mg. S2. First ball milling: Mix the weighed powder with alcohol in a nylon ball mill jar and ball mill in a planetary ball mill at 300 rpm for 24 hours. After drying, sieve through a 300-mesh screen to form a mixed raw material. S3. Pre-calcination: Place the sieved mixed raw materials in a muffle furnace at 880℃ and pre-calcine for 8 hours; S4. Second ball milling: Mix the pre-calcined powder with alcohol, ball mill again for 24 hours, dry and sieve through a 100-mesh sieve; S5. Slurry preparation: The ceramic powder after the second ball milling is mixed with an organic solvent and ball milled on a drum ball mill for 24 hours to prepare a casting slurry. The organic solvent is composed of 30wt.% ethanol + methyl ethyl ketone, 7wt% polyvinyl alcohol, 1wt% tributyl phosphate and 7wt% PVA. S6. Casting: After vacuum degassing the casting slurry, cast it on a casting machine. Adjust the relative height between the doctor blade and the PET film to 120μm, and the casting speed to 1.2m / min. Dry at 100℃. S7. Electrode printing: Print Ag-20wt%Pd electrodes on the surface of the dried green body, and then separate the film from the PET film. S8. Stacking and pressing: The films with electrodes are stacked sequentially according to the interdigitated electrode sequence using a stacking machine. The offset of the interdigitated electrodes is 300μm, and the error does not exceed 100μm. The stacked films are then pressed into shape in an isostatic press with a pressure of 100MPa. S9. Cutting: Use a wire cutting machine to cut the pressed multilayer film to 8×8×4mm according to the electrode arrangement. 3 Small pieces; S10, Low-temperature co-firing: Heat to 600℃ at a heating rate of 0.5℃ / min, hold for 2 hours to remove the glue, then heat to 980℃ at a heating rate of 0.5℃ / min, hold for 4 hours, and finally cool to room temperature at a cooling rate of 0.5℃ / min. S11. Subsequent processing: The edges of the fired multilayer piezoelectric ceramic are ground flat and chamfered. External electrodes are screen-printed on the side. After the electrodes are dried, they are placed in silicone oil at 90°C and polarized under an electric field of 2.5kV / mm. S12. Screening and Assembly: Test the displacement, impedance, loss, and leakage current electrical performance parameters of the multilayer ceramics, screen out the piezoelectric ceramics that meet the requirements, stack the multilayer units to the specified height using high-temperature resistant adhesive and solder copper wires on them, and test the electrical performance again.

4. The laminated piezoelectric ceramic vibration device for improving the strength and plasticity of laser additive manufacturing alloys according to claim 1, characterized in that: The internal structural components of the vibration platform (1) are all made of 304L stainless steel.

5. The multilayer piezoelectric ceramic vibration device for improving the strength and plasticity of laser additive manufacturing alloys according to claim 1, characterized in that: The components of the vibration platform (1) are connected by threaded connections.

6. The multilayer piezoelectric ceramic vibration device for improving the strength and plasticity of laser additive manufacturing alloys according to claim 1, characterized in that: The composite piezoelectric ceramic actuator (104) has the general formula xPb(Zr,Ti)O3-(1-x)Pb(Nb,Zn)O3-amol%Li2CO3-bmol%MnO2-cmol%Sm2O3, where 0≤x≤0.9, 0.2≤a≤0.6, 0≤b≤0.4, and 0.2≤c≤0.

4.

7. The multilayer piezoelectric ceramic vibration device for improving the strength and plasticity of laser additive manufacturing alloys according to claim 6, characterized in that: The optimal composition of the stacked piezoelectric ceramic actuator (104) is 0.7Pb(Zr,Ti)O3-0.3Pb(Nb,Zn)O3-0.5mol%Li2CO3-0.2mol%MnO2-0.2mol%Sm2O3.

8. The laminated piezoelectric ceramic vibration device for enhancing the strength and plasticity of laser additive manufacturing alloys according to claim 1, characterized in that: The perovskite lattice of the stacked piezoelectric ceramic actuator (104) is composed of three phases: tetragonal, trigonal and pseudocubic. It has few internal pores and defects, sufficient grain growth, and straight and continuous internal electrodes.

9. The multilayer piezoelectric ceramic vibration device for improving the strength and plasticity of laser additive manufacturing alloys according to claim 1, characterized in that: The function amplifier (4) controls the frequency and voltage of the electric field applied to the multilayer piezoelectric ceramic actuator (104) through the power amplifier (3), thereby achieving precise control of the amplitude and frequency of the vibration platform (1), with a frequency control range not exceeding 800Hz.

10. The multilayer piezoelectric ceramic vibration device for improving the strength and plasticity of laser additive manufacturing alloys according to claim 2, characterized in that: The inert gas protective box (2) is connected to a storage component (8) on the outside, which is used to transport metal powder and inert gas.

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