A method for manufacturing a multilayer heterogeneous ceramic, the manufactured multilayer heterogeneous ceramic, a manufacturing system using the method for manufacturing a multilayer heterogeneous ceramic, and an application of the manufactured multilayer heterogeneous ceramic

Abstract

This invention belongs to the field of multilayer dissimilar ceramics technology, specifically relating to a multilayer dissimilar ceramic and its preparation method. The preparation method of a multilayer dissimilar ceramic includes the following steps: S1, preparation of a multilayer ceramic green body; S2, moving the multilayer ceramic green body to a femtosecond laser processing area, starting the femtosecond laser, and performing non-thermal ablation cutting of the multilayer ceramic green body based on path planning of a scanning galvanometer system; S3, transferring it to a CO2 laser sintering station, starting a continuous CO2 laser, and using a line-focused laser beam to selectively co-sinter the cut area to obtain the multilayer dissimilar ceramic. This invention proposes and constructs a novel process for preparing multilayer dissimilar ceramics based on femtosecond laser micromachining and CO2 laser co-sintering. This method has strong controllability and low operational difficulty; this process combination of reduction followed by addition has not been reported to date.

Description

Technical Field

[0001] This invention belongs to the field of multilayer dissimilar ceramics technology, specifically relating to a method for preparing multilayer dissimilar ceramics, the obtained multilayer dissimilar ceramics, a manufacturing system using the method for preparing multilayer dissimilar ceramics, and the application of multilayer dissimilar ceramics. Background Technology

[0002] To meet the functional integration requirements of composite ceramic devices, co-sintering technology is increasingly demonstrating its engineering value. This technology, as a method of simultaneously sintering multiple materials under the same heat treatment conditions, can achieve simultaneous densification and synergistic molding of multiple ceramic materials in a single heat treatment process, offering significant advantages in structural integration and simplifying the manufacturing process while improving interfacial bonding strength. Current technology systems are mainly divided into two categories: high-temperature co-fired ceramics (HTCC) and low-temperature co-fired ceramics (LTCC). HTCC refers to a technology that simultaneously sintersects multiphase ceramic or metal green bodies into a dense, integrated structure in a high-temperature environment above 1300℃. HTCC possesses high mechanical strength, excellent heat resistance, and corrosion resistance, and is widely used in the manufacturing of electronic packaging and sensor devices in harsh environments such as high temperature, high power, and high frequency. LTCC refers to a multifunctional integrated manufacturing technology that simultaneously sintersects multiple ceramic materials with metal conductor materials (such as silver and copper) at sintering temperatures below 1000℃. The LTCC process allows for the stacking of multiple circuit layers and dielectric layers using methods such as printing and electroforming. While maintaining excellent dielectric properties, it offers advantages such as low cost, low thermal stress, and mass production capabilities, and is widely used in small and medium-sized devices such as radio frequency devices and oxide ceramic electrodes.

[0003] Laser processing, as a high-energy beam technology, has shown great potential in the additive manufacturing and sintering of ceramic materials in recent years. Existing research indicates that laser sintering technology has developed several pathways in ceramic sintering, including powder-based selective laser sintering (SLS), extrusion printing combined with laser-assisted sintering using ceramic slurry as a precursor, and CO2 laser direct melting forming technology for high-melting-point oxide ceramics. Among these, SLS technology selectively sintersulates ceramic powder using a laser beam, making it suitable for rapid prototyping and the manufacture of medium-density ceramic components.

[0004] However, existing HTCC and LTCC processes still have many limitations when dealing with complex ceramic devices constructed using multiple functions and materials. HTCC typically requires sintering at temperatures exceeding 1500°C, which not only leads to high energy consumption and long process cycles but also makes it prone to defects such as cracking and warping due to thermal expansion mismatch between dissimilar materials. While LTCC can achieve co-sintering of different ceramic materials at lower temperatures, secondary phases such as liquid glass phases, low-melting-point metals, or low-melting-point oxides are often added to the precursor of the ceramic phase to balance their sintering kinetics in order to reduce the thermal mismatch between the sintering temperature and different ceramic phases. When laser co-sintering is used, because the effective laser area is much smaller than the area of ​​the binder deposition region, the uneven and sharp temperature distribution may cause severe cracking and warping at the edges of the effective laser area, resulting in poor mechanical strength of the fabricated structure.

[0005] Therefore, there is an urgent need to develop a method for preparing multilayer dissimilar ceramics that can effectively solve the above problems. Summary of the Invention

[0006] This invention aims to provide a method for preparing multilayer dissimilar ceramics, the resulting multilayer dissimilar ceramics, a manufacturing system applying the method, and applications of multilayer dissimilar ceramics. This invention proposes and constructs a novel process for preparing multilayer dissimilar ceramics based on femtosecond laser micro-cutting and CO2 laser co-sintering. Using a CO2 laser as a heat source, by controlling its longitudinal temperature gradient, simultaneous and rapid densification sintering of dissimilar ceramics can be achieved without the addition of secondary phases, reducing heat loss and improving the overall forming efficiency and density quality. Furthermore, by introducing femtosecond laser micromachining into the ceramic additive manufacturing process, leveraging its non-thermal ablation characteristics, high-precision segmentation and microstructure pretreatment of ceramic green bodies can be achieved, thereby improving the freedom and accuracy of shape design and obtaining dissimilar ceramics with complex structures and high structural integrity and mechanical strength in the co-sintered ceramics. This method is highly controllable and easy to operate; this "subtraction-then-addition" process combination has not been reported to date.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing multilayer dissimilar ceramics, comprising the following steps: S1. Preparation of multilayer ceramic chloroplasts: The lower layer of slurry is applied using a coating blade and dried to form the lower layer of a multi-layered ceramic green body. The upper layer of slurry is then applied to the surface of the lower layer and dried to form a multi-layered ceramic green body. S2. Start the femtosecond laser and perform non-thermal ablation cutting on the multilayer ceramic green body based on the path planning of the scanning galvanometer system. S3. Start the continuous CO2 laser and use the line-focused laser beam to selectively co-sinter the cutting area of ​​the multilayer ceramic green body to obtain the multilayer dissimilar ceramic.

[0008] In one embodiment of the present invention, the densification sintering temperature of the lower slurry is not higher than the densification sintering temperature of the upper slurry.

[0009] In one embodiment of the present invention, the difference in the coefficient of linear expansion between the lower slurry and the upper slurry is ≤4×10. -6 / K.

[0010] The raw materials used for the upper and lower slurries in this invention can be used in the preparation method of this invention as long as they meet the above conditions (densification sintering temperature, difference in linear expansion coefficient) and do not undergo large-scale reactions or element volatilization under the target temperature-time history.

[0011] In one embodiment of the present invention, the coating speed is 30-50 mm / s.

[0012] In one embodiment of the present invention, the drying is performed at room temperature for 3 to 5 minutes.

[0013] In one embodiment of the present invention, the thickness of the lower layer after coating is 100-200 μm, the thickness of the upper layer after coating is 100-200 μm, and the ratio of the thickness of the upper layer to the thickness of the lower layer after coating is 0.8-1.5.

[0014] In this invention, the ratio of the thickness of the upper layer to the thickness of the lower layer after coating is kept within a suitable range. The CO2 laser can make the upper layer dense and the lower layer solid-state sintered and achieve a strong interface bond in a single path scan. If the ratio is exceeded, the lower layer will be under-sintered or melted, resulting in delamination or deformation, which will affect the performance of the final ceramic.

[0015] In one embodiment of the present invention, the lower slurry includes barium titanate slurry; the preparation method of the barium titanate slurry includes the following steps: mixing BaTiO3 powder with water, adding a dispersant, grinding, adding hydroxypropyl methylcellulose (HPMC), stirring, degassing, and obtaining the barium titanate slurry.

[0016] In one embodiment of the present invention, the upper slurry includes an alumina slurry; the preparation method of the alumina slurry includes the following steps: mixing Al2O3 powder with water, adding a dispersant, grinding, adding hydroxypropyl methylcellulose, stirring, degassing, and obtaining the alumina slurry.

[0017] In one embodiment of the present invention, the BaTiO3 powder is blocky BaTiO3 powder with an average particle size of less than 3 μm; the volume ratio of the BaTiO3 powder to water is 3:1.

[0018] In one embodiment of the present invention, the Al2O3 powder is spherical Al2O3 powder with an average particle size of less than 3 μm; the volume ratio of the Al2O3 powder to water is 1:1.

[0019] In one embodiment of the present invention, the dispersant in the barium titanate slurry and the alumina slurry includes ADS-20; the mass ratio of the dispersant to water is 0.5:99.5.

[0020] In one embodiment of the present invention, the amount of hydroxypropyl methylcellulose added to the barium titanate slurry and the alumina slurry is 0.5 to 1.5 wt% of the water content in the mixed system.

[0021] In one embodiment of the present invention, the grinding of the barium titanate slurry and the alumina slurry is performed by ball milling; the grinding time is 12 hours or more.

[0022] In one embodiment of the present invention, the stirring time for the barium titanate slurry and the alumina slurry is at least 30 minutes to ensure that there are no visible lumps in the slurry.

[0023] In one embodiment of the present invention, the femtosecond laser has a laser power of 20-24 W, a center wavelength of 1035 nm, a repetition frequency of 125-250 kHz, a scanning speed of 0.5-1 m / s, a pulse width of 265 fs, and a spot diameter of 20-30 μm.

[0024] In one embodiment of the present invention, the continuous CO2 laser has a laser power of 15-24 W, a center wavelength of 10.6 μm, a defocusing amount of 5 mm, a defocused spot size of 5 mm in length and 1 mm in width, and a scanning speed of 0.1-2 mm / s.

[0025] In the preparation method of the multilayer dissimilar ceramics of the present invention, when the laser power of the continuous CO2 laser is in a lower range (<15W), the laser energy density is significantly insufficient, and the input energy cannot reach the sintering temperature of the upper slurry (alumina) and the lower slurry (barium titanate). In this case, the ceramic is still in an unsintered state, with poor density and mechanical strength. When the laser power is in a higher range (>24W), the excessive energy will trigger an excessive heating effect, causing the material to undergo an undesirable melting phenomenon. This melting will greatly change the geometry of the ceramic and may even cause a large amount of interatomic diffusion, forming new substances, thereby affecting the physical and chemical properties of the final ceramic.

[0026] In one embodiment of the present invention, the line-focused laser beam is focused by setting a cylindrical lens under a continuous CO2 laser, so that the CO2 laser beam passes through the cylindrical lens and is focused, converting the Gaussian spot into a linear spot, which significantly increases the sintering area of ​​a single scan.

[0027] In one embodiment of the present invention, the focal length of the cylindrical lens is 50 mm.

[0028] In one embodiment of the present invention, the linear spot formed by the linearly focused laser beam has a size of 5-8 mm in length and 90-110 μm in width. The present invention uses a cylindrical lens to focus the laser beam, converting the Gaussian spot into a linear spot (size: 5-8 mm in length × 90-110 μm in width), which can significantly increase the sintering area in a single scan, thereby effectively ensuring the preparation of multilayer dissimilar ceramics with high shape design freedom and precision.

[0029] In a preferred embodiment of the present invention, the linear spot formed by the line-focused laser beam has a length of 7 mm and a width of 100 μm.

[0030] In the preparation method of this invention, the temperature peak and distribution depth of the temperature field can be controlled by adjusting the processing parameters (such as scanning speed, energy, etc.) of the continuous CO2 laser, thereby achieving different degrees of sintering of ceramic green bodies.

[0031] The preparation method of this invention employs a "reduction-then-increase" process sequence: femtosecond laser non-thermal micro-cutting followed by CO2 laser co-firing. The former allows the green body to form clean, steep boundaries, reducing constrained shrinkage stress and interface defects during co-firing; the latter, based on this, establishes a longitudinal temperature gradient through a linear laser spot, achieving simultaneous densification of the upper layer and solid-state sintering of the lower layer. When the order is reversed (CO2 laser first, then femtosecond laser), because the stress history is already fixed in the dense body and new defects are introduced by subsequent processing, it is impossible to obtain the comprehensive performance and repeatability comparable to the method of this invention. Specifically, this can be manifested as follows: (1) Macroscopic defects: In-plane thermal diffusion of ceramic green bodies without pre-segmentation by femtosecond laser is more significant. In order to make the lower layer also present a dense state, the power of CO2 laser often needs to be increased, which ultimately leads to an increase in the probability of warping / cracks / delamination.

[0032] (2) Interface and edge stress accumulation: The subsequent femtosecond laser post-processing on the compact body will introduce new gaps, which will disrupt the interface continuity. The interface critical load / shear strength is significantly lower than that of "femtosecond laser first, CO2 laser later".

[0033] The present invention also claims protection for a method for preparing multilayer dissimilar ceramics.

[0034] This invention also claims protection for a manufacturing system using the aforementioned method for preparing multilayer dissimilar ceramics, comprising a coating apparatus and a multi-laser processing system; the multi-laser processing system can operate on the coating apparatus; The multi-laser processing system includes an ultrafast laser module and a CO2 laser module, which are integrated into a high-precision three-axis processing platform. The laser parameters, scanning path, and motion platform of the two modules can be synchronously adjusted. The ultrafast laser module includes a femtosecond laser and a scanning galvanometer system; The CO2 laser module includes a continuous CO2 laser and a cylindrical lens; The cylindrical lens used for focusing CO2 laser and the scanning galvanometer system used for focusing femtosecond laser are both mounted on the z-axis of a three-axis machining platform, with a distance of 5 mm between the two laser focusing centers.

[0035] In one embodiment of the present invention, the coating apparatus includes a coating blade and a slide table.

[0036] In one embodiment of the present invention, the slide has a stroke of 200 mm, a moving speed range of 1 mm / s to 300 mm / s, and the coating blade can coat a maximum thickness of 10 mm.

[0037] In this invention, a slide table for controlling slurry coating is placed in the laser processing plane. By moving the slide table, the processes of slurry coating, laser cutting, and laser co-sintering can be realized sequentially, thereby achieving integrated manufacturing of multiple processes.

[0038] The limitation of parameters in the manufacturing system of this invention can effectively ensure the successful preparation of the final multilayer dissimilar ceramics, while ensuring the fine processing of complex patterns and the effective improvement of the structural integrity and mechanical strength of the co-sintered ceramics.

[0039] The present invention also claims protection for the application of the multilayer dissimilar ceramic prepared by the method described above in the fields of new energy vehicles, aerospace and high-end equipment, medical and health care, and energy.

[0040] Compared with the prior art, the present invention has the following beneficial effects: (1) In the preparation method of the present invention, the integrated production process of multilayer heterogeneous ceramic green body preparation, femtosecond laser precision processing and CO2 laser co-sintering is realized by the coordinated control of slurry coating system, three-dimensional motion platform and multiple laser modules.

[0041] (2) The process flow of the preparation method of the present invention is simple and easy to operate. After the prepared ceramic slurry is placed at the processing site, it can be operated in situ using a computer, which is very convenient. Compared with the traditional co-sintering process, the time required by the method of the present invention is greatly shortened, and the heat loss and energy loss are also greatly reduced, which can greatly improve production efficiency. The laser processing parameters can be precisely controlled, and samples with different sintering degrees can be prepared at any time, which greatly improves flexibility.

[0042] (3) Traditional co-sintering techniques produce dissimilar ceramic components with poor precision, rough surfaces, and simple structures. The preparation method of this invention integrates ultrafast lasers for micro-cutting and CO2 lasers for sintering. Through the synergistic effect of the non-thermal ablation effect of ultrafast lasers and the temperature gradient effect of CO2 lasers, synchronous and rapid sintering is achieved, reducing the influence of thermal expansion and internal stress. At the same time, it enables fine processing of complex patterns and effectively improves the structural integrity and mechanical strength of co-sintered ceramics. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the manufacturing system for the preparation method of multilayer dissimilar ceramics according to the present invention.

[0044] Figure 2 The appearance of the multilayer dissimilar ceramic prepared in Example 2 of the present invention.

[0045] Figure 3 The image shows the appearance of the multilayer dissimilar ceramic prepared in Comparative Example 1 of this invention.

[0046] Figure 4 The image shows the appearance of the multilayer dissimilar ceramic prepared in Comparative Example 2 of this invention.

[0047] Figure 5 This is a schematic diagram of the sintering of BaTiO3-Al2O3 ceramics under different processing parameters (scanning power and scanning speed) in an embodiment of the present invention.

[0048] Figure 6 This is a schematic diagram of the sintering of BaTiO3-Al2O3 ceramics under different processing parameters (scanning power and layer thickness ratio) in an embodiment of the present invention.

[0049] Figure 7 This is a schematic diagram showing five different interlayer bonding results under sintering parameters with different thickness ratios and power in the embodiments of the present invention.

[0050] Figure 8 This is a diagram showing the nanoindentation test results of multilayer dissimilar ceramics in an embodiment of the present invention.

[0051] Figure 9This is a schematic diagram of BaTiO3-Al2O3 composite ceramic devices with different morphologies and sizes in embodiments of the present invention.

[0052] Figure label: 1. Coating blade; 2. Slide table; 3. Femtosecond laser; 4. Scanning galvanometer system; 5. Continuous CO2 laser; 6. Cylindrical lens; 7. Reflector; 8. Computer control center; 9. Slurry; 10. Three-axis machining platform. Detailed Implementation

[0053] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0054] Unless otherwise specified, the experimental methods used in the examples and comparative examples are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0055] The preparation method of multilayer dissimilar ceramics in this embodiment of the invention includes the following steps: S1. Preparation of multilayer ceramic chloroplasts: Prepare the lower layer slurry, place the slurry on a quartz glass substrate, and place the quartz glass substrate on a slide table. Control the slide table to move the quartz glass substrate through the coating doctor blade, and dry it to complete the coating of the lower layer. Prepare the upper layer slurry, repeat the above process to coat the upper layer slurry onto the surface of the lower layer, and dry it to form a multi-layer ceramic green body. The lower layer slurry is barium titanate slurry; The preparation method of the barium titanate slurry includes the following steps: Selecting blocky BaTiO3 powder with an average particle size of less than 3 μm and mixing it with deionized water at a volume ratio of 3:1, adding dispersant ADS-20 (mass ratio ADS-20∶H2O=0.5∶99.5) to improve the uniform dispersion of the powder, and ball milling in a ball mill for more than 12 h to further reduce particle agglomeration and enhance the fluidity and uniformity of the slurry. Subsequently, to obtain more suitable viscosity and thixotropic properties, hydroxypropyl methylcellulose (HPMC) of approximately 1 wt% of the deionized water content of the mixed system is added in batches to the ball-milled slurry, and stirred for at least 30 min to ensure that there are no visible lumps in the slurry. Finally, it is placed in a vacuum degassing machine to remove air bubbles to obtain a barium titanate slurry with uniform texture. The upper slurry is an alumina slurry; The preparation method of the alumina slurry includes the following steps: Spherical Al2O3 powder with an average particle size of less than 3 μm is selected and mixed with deionized water at a volume ratio of 1:1. Dispersant ADS-20 (mass ratio ADS-20∶H2O=0.5∶99.5) is added to improve the uniform dispersion of the powder. The mixture is ball-milled for more than 12 hours to further reduce particle agglomeration and enhance the fluidity and uniformity of the slurry. Subsequently, in order to obtain more suitable viscosity and thixotropic properties, hydroxypropyl methylcellulose (HPMC) of approximately 1 wt% of the deionized water content of the mixed system is added in batches to the ball-milled slurry, and the mixture is stirred for at least 30 minutes to ensure that there are no visible lumps in the slurry. Finally, the slurry is placed in a vacuum degassing machine to remove air bubbles and obtain a uniform alumina slurry. The drying process is performed at room temperature for 3-5 minutes. The thickness of the lower layer after coating is 100-200 μm, the thickness of the upper layer after coating is 100-200 μm, and the ratio of the thickness of the upper layer to the thickness of the lower layer after coating is 0.8~1.5.

[0056] S2. Move the multi-layer ceramic green body to the femtosecond laser processing area, start the femtosecond laser, and perform non-thermal ablation cutting on the multi-layer ceramic green body based on the path planning of the scanning galvanometer system. The femtosecond laser has a laser power of 20-24 W, a center wavelength of 1035 nm, a repetition frequency of 125-250 kHz, a scanning speed of 0.5-1 m / s, a pulse width of 265 fs, and a spot diameter of 20-30 μm.

[0057] S3. Transfer to the CO2 laser sintering station, start the continuous CO2 laser, and use the line-focused laser beam to selectively co-sinter the cutting area to obtain the multilayer dissimilar ceramic. The continuous CO2 laser has a laser power of 15-24 W, a center wavelength of 10.6 μm, a defocusing amount of 5 mm, a defocused spot size of 5 mm long × 1 mm wide, and a scanning speed of 0.1-2 mm / s. The linearly focused laser beam is focused by placing a cylindrical lens under a continuous CO2 laser, allowing the CO2 laser to pass through the cylindrical lens and converting the Gaussian spot into a linear spot; the focal length of the cylindrical lens is 50 mm; the size of the linear spot is 7 mm long × 100 μm wide.

[0058] Example 1

[0059] See appendix Figure 1 The manufacturing system using the multilayer dissimilar ceramic preparation method in this embodiment of the invention includes a coating device and a multi-laser processing system; The coating device includes a coating blade 1 and a computer-controlled slide table 2; The slide table 2 has a stroke of 200 mm and a moving speed range of 1 mm / s to 300 mm / s. The coating blade 1 can coat a maximum thickness of 10 mm. The multi-laser processing system can be applied to the coating device; The multi-laser processing system includes an ultrafast laser module and a CO2 laser module, which are integrated into a high-precision three-axis processing platform 10. The synchronous control of laser parameters, scanning path and motion platform is achieved through a computer control center 8. The ultrafast laser module includes a femtosecond laser 3 and a scanning galvanometer system 4; The CO2 laser module includes a continuous CO2 laser 5 and a cylindrical lens 6; The three-axis machining platform 10 establishes a workpiece coordinate system. The cylindrical lens 6 for focusing the CO2 laser and the scanning galvanometer system 4 for focusing the femtosecond laser are both mounted on the z-axis of the three-axis machining platform 10, with a distance of 5 mm between the two laser focusing centers. The coating device is located within the machining surface of the three-axis machining platform 10; the slide 2 supports the composite ceramic body and provides horizontal linear motion; the coating scraper 1 is located above the movement path of the slide 2 and parallel to the machining surface, so that the slurry 9 forms a uniform coating during the relative movement of the slide 2.

[0060] The computer control center 8 is an industrial control computer with built-in process parameter management and path planning software. It is electrically connected to the motion control unit of the three-axis machining platform 10, the galvanometer control unit of the scanning galvanometer system 4, and communicatively connected to the laser control interfaces of the femtosecond laser 3 and the continuous CO2 laser 5. The motion control unit receives and executes displacement, velocity, acceleration, and interpolation trajectory commands issued by the computer control center 8 to drive the three-axis machining platform 10 to complete workpiece positioning and scanning motion. The galvanometer control unit receives and executes scanning vector data and filling strategy parameters issued by the computer control center 8 to drive the scanning galvanometer system 4 to complete a predetermined scanning path. The femtosecond laser 3 and the continuous CO2 laser 5 are connected to the computer control center 8 through a power setting interface and a light emission gating interface, respectively, to set the laser output power / frequency / pulse width (for the femtosecond laser) and output power (for the CO2 laser), and to switch the laser on and off as needed.

[0061] The operation process of the manufacturing system includes: (1) Coating stage: The computer control center 8 controls the slide table 2 to move at a set speed and controls the coating blade 1 to complete the coating of the slurry 9 at a set gap; (2) Segmentation stage: After drying is completed, the computer control center 8 calls the femtosecond laser processing path file, controls the three-axis processing platform 10 to position to the target area (femtosecond laser processing area), and controls the scanning galvanometer system 4 to scan according to the predetermined trajectory. At the same time, the femtosecond laser 3 is turned on through the synchronous trigger signal to realize the segmentation of the composite green body. (3) Co-sintering stage: The computer control center 8 calls the CO2 laser co-sintering path file, performs coordinate compensation based on the 5 mm focus offset, controls the three-axis machining platform 10 to perform line scanning, and turns on the continuous CO2 laser 5 through the synchronous trigger signal, so that the CO2 laser forms a line focusing heat source through the cylindrical lens 6 to co-fire the composite green body in one step, and obtains the final multilayer dissimilar ceramic.

[0062] Example 2

[0063] A method for preparing multilayer dissimilar ceramics includes the following steps: S1. Preparation of multilayer ceramic chloroplasts: A ceramic lower layer slurry was applied to a commercial quartz glass substrate using a scraper coating device. The substrate was then dried at room temperature for 3 minutes to cure it into a crack-free multilayer ceramic green body lower layer. After the lower layer was completely cured, the upper layer slurry was precisely applied to the surface of the lower layer and dried at room temperature for 3 minutes to form a multilayer ceramic green body. The lower layer slurry is barium titanate slurry; The upper slurry is an alumina slurry; The drying process was performed at room temperature for 4 minutes. The thickness of the lower layer after coating is 150 μm, the thickness of the upper layer after coating is 150 μm, and the ratio of the thickness of the upper layer to the thickness of the lower layer after coating is 1.0 (150 μm: 150 μm).

[0064] S2. Move the multi-layer ceramic green body to the femtosecond laser processing area, start the femtosecond laser, and perform non-thermal ablation cutting on the multi-layer ceramic green body based on the path planning of the scanning galvanometer system. The femtosecond laser has a laser power of 22 W, a center wavelength of 1035 nm, a repetition rate of 200 kHz, a scanning speed of 0.8 m / s, a pulse width of 265 fs, and a spot diameter of 25 μm.

[0065] S3. Transfer to the CO2 laser sintering station, start the continuous CO2 laser, and use the line-focused laser beam to selectively co-sinter the cutting area to obtain the multilayer dissimilar ceramic. The continuous CO2 laser has a laser power of 16.5 W, a center wavelength of 10.6 μm, a defocusing amount of 5 mm, a defocused spot size of 5 mm long × 1 mm wide, and a scanning speed of 0.5 mm / s. The linearly focused laser beam is focused by placing a cylindrical lens under a continuous CO2 laser, allowing the CO2 laser to pass through the cylindrical lens and converting the Gaussian spot into a linear spot; the focal length of the cylindrical lens is 50 mm; the size of the linear spot is 7 mm long × 100 μm wide.

[0066] In this embodiment, both Al2O3 and BaTiO3 ceramic slurries exhibit excellent dispersion stability. The ceramic particles fully combine with HPMC in the aqueous medium to form a homogeneous suspension system. This system displays unique curing characteristics during the drying stage: as moisture evaporates, HPMC molecular chains form a three-dimensional network structure between the ceramic particles. This temporary skeleton constructed by the organic binder not only provides sufficient mechanical strength to the green body but also inhibits its drying shrinkage, thereby ensuring that the formed green body maintains a precise geometric morphology on a macroscopic scale. Subsequently, the dried composite ceramic green body is non-thermal ablation cut using a femtosecond laser. Due to the non-thermal ablation characteristics of the femtosecond laser, its ultrashort pulse action allows the material to be directly ionized to generate plasma through multiphoton absorption. This mechanism can significantly reduce the thermal diffusion phenomenon during processing, thereby eliminating the heat-affected zone and ensuring the steepness of the cut edge. After cutting, the ceramic green body is directly transferred to the CO2 laser zone for the final co-sintering process. When the high-power CO2 laser acts on the green body, its 10.6 μm wavelength is strongly absorbed by the ceramic particles, forming a unique longitudinal temperature gradient field: the surface layer rapidly heats up to above 1600℃ due to the high energy flux density, promoting the densification of the Al2O3 layer; while the lower layer maintains a medium-temperature environment of 800-1280℃ through heat conduction, which perfectly meets the solid-state sintering requirements of BaTiO3. This gradient sintering mechanism enables the heterogeneous materials to achieve simultaneous densification in a single laser scan, and the binder HPMC is also completely decomposed by heat. Thanks to the high edge smoothness brought about by femtosecond laser treatment, the edge defects caused by the Gaussian distribution of CO2 laser energy are effectively improved, thereby improving the structural integrity and mechanical strength of the co-sintered ceramic.

[0067] Experimental results are as follows Figure 2 As shown. In this embodiment, by combining femtosecond laser and CO2 laser, the one-step co-firing preparation of multilayer dissimilar ceramics with good edge smoothness and high interfacial bonding strength is achieved through the synergistic effect of the two.

[0068] Example 3

[0069] Compared with Example 2, the only difference in this example is that the laser power of the continuous CO2 laser is 15 W.

[0070] The preparation method of multilayer dissimilar ceramics is described in Example 2.

[0071] Example 4

[0072] Compared with Example 2, the only difference in this example is that the laser power of the continuous CO2 laser is 18 W.

[0073] The preparation method of multilayer dissimilar ceramics is described in Example 2.

[0074] Example 5

[0075] Compared with Example 2, the only difference in this example is that the laser power of the continuous CO2 laser is 19.5W.

[0076] The preparation method of multilayer dissimilar ceramics is described in Example 2.

[0077] Example 6

[0078] Compared with Example 2, the only difference in this example is that the laser power of the continuous CO2 laser is 21 W.

[0079] The preparation method of multilayer dissimilar ceramics is described in Example 2.

[0080] Example 7

[0081] Compared with Example 2, the only difference in this example is that the laser power of the continuous CO2 laser is 22.5W.

[0082] The preparation method of multilayer dissimilar ceramics is described in Example 2.

[0083] Example 8

[0084] Compared with Example 2, the only difference in this example is that the laser power of the continuous CO2 laser is 24 W.

[0085] The preparation method of multilayer dissimilar ceramics is described in Example 2.

[0086] The laser power and scanning speed parameters of the continuous CO2 lasers in Examples 2-8 are shown in Table 1.

[0087] Table 1

[0088] Examples 9-15

[0089] Compared with Examples 2-8, the only difference between Examples 9-15 is that the scanning speed parameters of the continuous CO2 laser are different, as shown in Table 2.

[0090] The preparation method of multilayer dissimilar ceramics is described in Example 2.

[0091] Table 2

[0092] Examples 16-22

[0093] Compared with Examples 2-8, the only difference between Examples 16-22 is that the scanning speed parameters of the continuous CO2 laser are different, as shown in Table 3.

[0094] The preparation method of multilayer dissimilar ceramics is described in Example 2.

[0095] Table 3

[0096] Examples 23-29

[0097] Compared with Examples 2-8, the only difference between Examples 23-29 is that the thickness ratio parameters of the alumina layer and the barium titanate layer are different, as shown in Table 4.

[0098] The preparation method of multilayer dissimilar ceramics is described in Example 2.

[0099] Table 4

[0100] Examples 30-36

[0101] Compared with Examples 2-8, the only difference between Examples 30-36 is that the thickness ratio parameters of the alumina layer and the barium titanate layer are different, as shown in Table 5.

[0102] The preparation method of multilayer dissimilar ceramics is described in Example 2.

[0103] Table 5

[0104] Example 37

[0105] According to the preparation method of Example 2, multilayer dissimilar ceramics were prepared into multilayer dissimilar ceramics with a thickness of 1 mm and a stepped outer contour.

[0106] Example 38

[0107] According to the preparation method of Example 2, multilayer dissimilar ceramics were prepared into multilayer dissimilar ceramics with a thickness of 2 mm and a stepped outer contour.

[0108] Example 39

[0109] According to the preparation method of Example 2, multilayer dissimilar ceramics were prepared into multilayer dissimilar ceramics with a thickness of 1 mm and an outer ring outline.

[0110] Example 40

[0111] According to the preparation method of Example 2, multilayer dissimilar ceramics were prepared into multilayer dissimilar ceramics with a thickness of 2 mm and an outer ring outline.

[0112] Example 41

[0113] Following the preparation method of Example 2, multilayer dissimilar ceramics were prepared into multilayer dissimilar ceramics with a triangular array through-hole structure and a thickness of 1 mm.

[0114] Example 42

[0115] Following the preparation method of Example 2, multilayer dissimilar ceramics were prepared into multilayer dissimilar ceramics with a triangular array through-hole structure and a thickness of 2 mm.

[0116] Example 43

[0117] Following the preparation method of Example 2, multilayer dissimilar ceramics were prepared into multilayer dissimilar ceramics with a square array through-hole structure and a thickness of 1 mm.

[0118] Example 44

[0119] Following the preparation method of Example 2, multilayer dissimilar ceramics were prepared into multilayer dissimilar ceramics with a square array through-hole structure and a thickness of 2 mm.

[0120] Examples 45-50

[0121] Following the preparation method of Example 2, multilayer dissimilar ceramics were prepared into circular and square devices of different specifications, and the specific parameters are shown in Table 6.

[0122] Table 6

[0123] Comparative Example 1 Compared with Example 2, the only difference in this comparative example is that step S3 is not performed.

[0124] The preparation method is the same as in Example 2.

[0125] Experimental results are as follows Figure 3 As shown, when a femtosecond laser beam bombards the surface of a ceramic green body, its ultrashort pulse effect causes the material to be directly ionized to generate plasma through multiphoton absorption rather than sintering. A single femtosecond laser cannot achieve the co-sintering of multilayer heterogeneous composite ceramics.

[0126] Comparative Example 2 Compared with Example 2, the only difference in this comparative example is that step S2 is not performed.

[0127] The preparation method is the same as in Example 2.

[0128] Experimental results are as follows Figure 4As shown, although a single CO2 laser can enable ceramic green bodies to complete co-sintering, the Gaussian distribution of its laser energy inevitably results in defects such as cracks, warping, and unevenness at the edges of the sintered sample.

[0129] Experimental Example 1: Influence of CO2 Laser Processing Parameters on the Sintering Quality and Morphology Evolution of Multilayer Dissimilar Ceramics (1) Multilayer dissimilar ceramics were prepared according to the preparation method of Example 2, and the sintering of BaTiO3-Al2O3 ceramics obtained in Examples 2-22 was verified and observed.

[0130] Experimental results are as follows Figure 5 As shown, different sintered samples are arranged according to increasing laser power from left to right on the horizontal axis and increasing scanning speed from top to bottom on the vertical axis. From Figure 5 The experimental results show that when the scanning speed is low and the laser power is not high, the sample surface is flat and basically dense, but some cracks or local micro-defects will appear. When the scanning speed is increased, but the laser power is still at a low level, the laser heat cannot be fully concentrated, resulting in poor bonding or even failure to bond the sample. As the power increases or the scanning speed increases, the sample will gradually transition to the "incomplete sintering zone", and uneven sintering will occur on the surface. When the power is further increased and the speed is low, the laser heat accumulates excessively, and local areas will experience excessive melting accompanied by collapse or deformation.

[0131] (2) Multilayer dissimilar ceramics were prepared according to the preparation method of Example 2. The scanning speed was fixed at 0.5 mm / s and the thickness of the barium titanate layer was 150 μm. The sintering of BaTiO3-Al2O3 ceramics prepared in Examples 2-8 and Examples 23-36 was observed by changing the thickness of the alumina layer in the multilayer dissimilar ceramic from 50 μm to 250 μm.

[0132] Experimental results are as follows Figure 6-7 As shown. From Figure 6 It can be seen that the CO2 laser power required to complete co-sintering increases significantly with the increase of alumina layer thickness. When the alumina layer is thick (250 μm), the sintering conditions become extremely demanding, and the suitable power window is compressed to a narrow range (19.5W-22.5W), exhibiting a "convergence effect". A slightly higher laser power will cause the upper layer to melt, while a slightly lower power will not meet the densification requirements of the lower layer. The operating tolerance is significantly reduced, which leads to an increase in the difficulty of controlling the sintering process.

[0133] Five different sintering states that occur after the sintering process is completed, such as Figure 7As shown, when the laser energy density is insufficient, the heat penetrating to the barium titanate layer is insufficient for sintering, resulting in the upper layer sintering while the lower layer remains unsintered. In this case, the interlayer bonding is weak, and the sample often exhibits delamination. However, when the laser energy density is too high, the excess energy causes the composite ceramic to melt directly. While melting strengthens the interlayer bonding, it often leads to collapse or deformation, resulting in undesirable changes in physical properties. When the layer thickness ratio is too small, the heat penetrating to the barium titanate layer exceeds the heat required for sintering, causing the barium titanate layer to melt faster than the alumina layer. Conversely, when the layer thickness ratio is too large, the alumina layer absorbs most of the laser energy, resulting in a special case where the alumina layer melts while the barium titanate layer sinters. However, in this case, the lower layer is not fully densified.

[0134] Experimental Example 2: Verifying the Sintering Effect of Multilayer Dissimilar Ceramics from a Mechanical Perspective Nanoscale scratch tests were conducted on three groups of multilayer dissimilar ceramic samples (Examples 4-6) obtained by sintering under different laser powers. A Rockwell-type diamond probe (radius 100 μm) was used. During the test, the change in frictional force during the probe loading process was recorded to extract the critical load for interface failure of the samples, and the interfacial bonding strength of the three groups of multilayer dissimilar ceramic samples was calculated.

[0135] Experimental results are as follows Figure 8 As shown. A Rockwell-type diamond probe (100 μm radius) was used. During the test, the change in frictional force during the probe loading process was recorded to extract the critical loads for interface failure of the samples, which were 1760.42 mN (Example 4), 2762.92 mN (Example 5), and 3257.19 mN (Example 6). Through calculation, the interfacial bonding strengths of the composite ceramics were found to be 451.67 MPa (Example 4), 733.16 MPa (Example 5), and 3.826 GPa (Example 6), showing a good trend of strength increase.

[0136] Experimental Example 3: Verification of the Geometric Adaptability of the Invention's Preparation Method in the Fabrication of Complex Structure Ceramic Devices BaTiO3-Al2O3 composite ceramic devices with various structural forms and sizes can be prepared according to the preparation method in Example 2. For example... Figure 9 As shown in (ad), two typical structures, contour-type and through-hole-type, are illustrated, including stepped and annular outer contours. Figure 9 (a, b), Examples 37-40), and triangular and square array through-hole structures ( Figure 9(c, d), Examples 41-44), fully demonstrate the high degree of customization capability of the femtosecond laser cutting process for the morphology of ceramic chloroplasts. Simultaneously, the laser co-firing technology of this invention also exhibits excellent dimensional control capabilities, successfully achieving the fabrication of circular and square devices of different specifications ranging from 3.0 to 4.5 mm. Figure 9 (e), Examples 45-50).

[0137] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing multilayer dissimilar ceramics, characterized in that, Includes the following steps: S1. Preparation of multilayer ceramic chloroplasts: The lower layer of slurry is applied using a coating blade and dried to form the lower layer of a multi-layered ceramic green body. The upper layer of slurry is then applied to the surface of the lower layer and dried to form a multi-layered ceramic green body. S2. Start the femtosecond laser and perform non-thermal ablation cutting on the multilayer ceramic green body based on the path planning of the scanning galvanometer system. S3. Start the continuous CO2 laser and use the line-focused laser beam to selectively co-sinter the cutting area of ​​the multilayer ceramic green body.

2. The method for preparing multilayer dissimilar ceramics as described in claim 1, characterized in that, It must include at least one of the following (1) to (5): (1) The densification sintering temperature of the lower slurry is not higher than the densification sintering temperature of the upper slurry; (2) The difference in the coefficient of linear expansion between the lower slurry and the upper slurry is ≤4×10 -6 / K; (3) The coating speed is 30-50 mm / s; (4) The drying process is performed at room temperature for 3-5 minutes; (5) The thickness of the lower layer after coating is 100-200 μm, the thickness of the upper layer after coating is 100-200 μm, and the ratio of the thickness of the upper layer to the thickness of the lower layer after coating is 0.8~1.

5.

3. The method for preparing multilayer dissimilar ceramics as described in claim 1, characterized in that, The lower layer slurry includes barium titanate slurry; the preparation method of the barium titanate slurry includes the following steps: mixing BaTiO3 powder with water, adding a dispersant, grinding, adding hydroxypropyl methylcellulose, stirring, degassing, and obtaining the barium titanate slurry; The upper slurry includes an alumina slurry; the preparation method of the alumina slurry includes the following steps: mixing Al2O3 powder with water, adding a dispersant, grinding, adding hydroxypropyl methylcellulose, stirring, degassing, and obtaining the alumina slurry.

4. The method for preparing multilayer dissimilar ceramics as described in claim 3, characterized in that, It must include at least one of the following (1) to (6): (1) The BaTiO3 powder is blocky BaTiO3 powder with an average particle size of less than 3 μm; the volume ratio of the BaTiO3 powder to water is 3:1; (2) The Al2O3 powder is spherical Al2O3 powder with an average particle size of less than 3 μm; the volume ratio of the Al2O3 powder to water is 1:1; (3) In the barium titanate slurry and the alumina slurry, the dispersant includes ADS-20; the mass ratio of the dispersant to water is 0.5:99.5; (4) In the barium titanate slurry and the alumina slurry, the amount of hydroxypropyl methylcellulose added is 0.5~1.5 wt% of the water content in the mixed system; (5) In the barium titanate slurry and the alumina slurry, the grinding is performed by ball milling; the grinding time is more than 12 hours. (6) The stirring time for the barium titanate slurry and the alumina slurry is at least 30 min.

5. The method for preparing multilayer dissimilar ceramics as described in claim 1, characterized in that, The femtosecond laser has a laser power of 20-24 W, a center wavelength of 1035 nm, a repetition frequency of 125-250 kHz, a scanning speed of 0.5-1 m / s, a pulse width of 265 fs, and a spot diameter of 20-30 μm.

6. The method for preparing multilayer dissimilar ceramics as described in claim 1, characterized in that, The continuous CO2 laser has a laser power of 15-24 W, a center wavelength of 10.6 μm, a defocusing amount of 5 mm, a defocused spot size of 5 mm long × 1 mm wide, and a scanning speed of 0.1-2 mm / s.

7. The method for preparing multilayer dissimilar ceramics as described in claim 1, characterized in that, It must include at least one of the following (1) to (2): (1) The line-focused laser beam is focused by setting a cylindrical lens under the continuous CO2 laser, so that the CO2 laser beam passes through the cylindrical lens and the laser beam is focused, converting the Gaussian spot into a linear spot; (2) The size of the linear spot formed by the line-focused laser beam is 5-8 mm long × 90-110 μm wide.

8. A multilayer dissimilar ceramic prepared by the preparation method of any one of claims 1 to 7.

9. A manufacturing system employing the preparation method of multilayer dissimilar ceramics as described in any one of claims 1 to 7, characterized in that, Includes coating equipment and multi-laser processing systems; The multi-laser processing system can be applied to the coating device; The multi-laser processing system includes an ultrafast laser module and a CO2 laser module, which are integrated into a three-axis processing platform. The laser parameters, scanning path, and motion platform of the two modules can be synchronously adjusted. The ultrafast laser module includes a femtosecond laser and a scanning galvanometer system; The CO2 laser module includes a continuous CO2 laser and a cylindrical lens; The cylindrical lens used for focusing CO2 laser and the scanning galvanometer system used for focusing femtosecond laser are both mounted on the z-axis of a three-axis machining platform, and the distance between the two laser focusing centers is 5 mm.

10. The manufacturing system as claimed in claim 9, characterized in that, The coating device includes a coating blade and a slide table.

11. The application of a multilayer dissimilar ceramic as described in claim 8 in the fields of new energy vehicles, aerospace and high-end equipment, medical and health care, and energy.

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