A modular method for light-curing 3D printing ceramics

Abstract

A modular photocuring 3D printing method for ceramics relates to a 3D printing method for photocuring ceramics. The method aims to solve the problem that existing methods cannot achieve block 3D printing of ceramic parts. The method comprises the following steps: using software on a computer to split the 3D model of the target large-scale structural ceramic into interconnected modules, and then importing the 3D model into a DLP printer; then using the ceramic slurry corresponding to each module to perform DLP printing to obtain each module; after cleaning and drying each module, applying n-butyl acetate to the connection interface between the modules, applying pressure to connect the modules together to obtain an integrated preform; and then degreasing and high-temperature sintering to obtain the 3D printed ceramic. The ceramic connection interface obtained by the present invention is defect-free, has a microstructure consistent with the interface of the main body, and has no cracks on the connection interface. The method of the present invention can be used in the field of 3D printing ceramics.

Description

Technical Field

[0001] The invention relates to a 3D printing method for light-cured ceramics. Background Art

[0002] Ceramics are an essential material in our daily lives and in society's production and construction. The expansion of ceramic applications in diverse fields is accompanied by an increasing demand for ceramic materials in various sizes, with complex geometries and multiple materials. Compared to traditional manufacturing techniques, 3D printing technology, with its layer-by-layer construction method, allows for the flexible and efficient creation of complex and precise structures without relying on molds, significantly increasing design freedom and potentially revolutionizing the ceramic manufacturing industry.

[0003] Currently, for larger 3D-printed parts, a block-by-block printing method can be used. For example, Chinese patent application number CN201610497849.3, "Method for Forming Sanitary Ceramic Molds Based on 3D Printing Technology," discloses a method that first divides a 3D model into blocks using a 3D printer and then prints each block. Each block is then polished and smoothed, and then bonded together with adhesive to form a plastic solid model. This is then used to mass-produce sanitary ceramic molds. Chinese patent application number 201711153154.4, "Method for 3D Printing Large Sculpture Models," discloses a method that uses conventional printing equipment to print a thin model in blocks, and then bonds the assembled surfaces together with slow-drying resin glue. However, existing methods that rely on adhesives cannot achieve block-by-block 3D printing of ceramic parts, because the printed parts (green parts) of ceramic parts need to undergo high-temperature degreasing and sintering to become ceramics. The highest temperature of the process generally reaches 1500-2000°C. The adhesive or resin glue used to bond the interface of the green parts decomposes due to heat during the degreasing and sintering process, causing the assembly interface to separate, making it impossible to obtain an integrated ceramic material. Summary of the Invention

[0004] The present invention aims to solve the technical problem that existing methods cannot achieve block 3D printing of ceramic parts, and provides a modular light-curing 3D printing method for ceramics. This method can form both single-material ceramic materials and multi-material gradient ceramic materials.

[0005] The modular light-curing 3D printing ceramic method of the present invention comprises the following steps:

[0006] 1. Use software on a computer to split the 3D model of the target large-scale structural ceramic into interconnected modules of the same material, or into interconnected modules with gradient material changes, where the connection surfaces of each module are planar connection interfaces; and then import the 3D models of each module into a DLP printer;

[0007] 2. Prepare ceramic slurry: Weigh acrylate monomer, polymerized acrylate, ceramic powder, dispersant, and photoinitiator and add them to a ball mill and mix evenly to obtain ceramic slurry for printing each module; the mass of polymerized acrylate is 3% to 15% of the mass of acrylate monomer;

[0008] 3. Pour the ceramic slurry corresponding to each module into the material tank of the DLP printer, start it, and perform light-curing printing on each module to obtain a green body of multiple modules;

[0009] Fourth, remove the module green body from the printing platform and clean the residual slurry on the surface of the module with water; after cleaning and drying, apply n-butyl acetate to the connection interface between the modules, and apply pressure on both sides of the interface and maintain it for 10 to 30 minutes. The multiple modules are connected into one to obtain an integrated preform;

[0010] 5. Place the integrated preform into a sintering furnace, heat it to 120-125°C at a heating rate of 0.2-2°C / min and keep it warm for 2-5 hours, then heat it to 150-155°C and keep it warm for 2-5 hours, and finally heat it to 600-620°C and keep it warm for 2-5 hours for degreasing; then sinter it at high temperature to obtain 3D printed ceramics.

[0011] Furthermore, the acrylate monomer in step 1 is one or a combination of isobornyl acrylate, isobornyl methacrylate, neobornyl acrylate, neobornyl methacrylate and isobornyl diester acrylate.

[0012] Furthermore, the preparation method of the polymerized acrylate described in step 1 is: adding a photoinitiator accounting for 0.3% to 8% by mass of the acrylate monomer to the acrylate monomer, mixing evenly, and performing photocuring 3D printing with a DLP printer to obtain the polymerized acrylate.

[0013] Furthermore, the ceramic slurry of the modules of the same material contains ceramic powders such as alumina ceramic powder or zirconia ceramic powder.

[0014] Furthermore, for the modules with a gradient material change described in step 1, the ceramic powder in the ceramic slurry used to prepare the modules is replaced by a different type of ceramic powder, replacing 5% to 10% of the ceramic powder in the previous module's ceramic slurry by weight, according to the order in which the modules are connected. The modules thus constructed have a gradient material change in the newly added ceramic powder.

[0015] Furthermore, the ceramic slurry of the modules with gradient material changes, the ceramic powder in the ceramic slurry of the first module is alumina ceramic powder, and from the second module onwards, the ceramic powder in the ceramic slurry of the latter module is the alumina ceramic powder in the ceramic slurry of the previous module replaced with zirconium oxide ceramic powder at a rate of 5% to 10% by mass.

[0016] Furthermore, the dispersant in step 2 is dispersant BYK.

[0017] Furthermore, the photoinitiator in step 2 is 819 or TPO photoinitiator.

[0018] Furthermore, the mass of the dispersant in step 2 is 1% to 5% of the mass of the ceramic powder.

[0019] Furthermore, the mass of the photoinitiator in step 2 is 0.3% to 8% of the sum of the mass of the acrylate monomer and the polymerized acrylate.

[0020] Furthermore, the volume of the ceramic powder in step 2 is 40% to 50% of the total volume of the mixed ceramic slurry.

[0021] Furthermore, in step 4, n-butyl acetate is coated on the connection interface, and the coating amount of n-butyl acetate is 20μL to 30μL per square centimeter; the connection interface of the stimulation module is infiltrated with n-butyl acetate. Due to the extremely strong solubility of n-butyl acetate solvent for polymerized acrylate, the polymerized acrylate molecular chains at the interface are disentangled, forming a gel layer structure with a certain fluidity at the interface. Under external pressure, the two gel layers at the connection interface undergo mutual diffusion movement. With the mutual diffusion and solvent evaporation, a new bonding surface is formed at the connection, thereby realizing a bulk connection interface of the green material that does not rely on adhesives or other resin glues, such as Figure 1 shown.

[0022] Furthermore, the high-temperature sintering described in step five is sintering at a temperature of 1600-1700°C for 1-5 hours. The sintering temperature and time are determined according to the type of ceramic. For ceramics of different materials, the sintering temperature and time are determined according to the material with the highest sintering temperature.

[0023] The modular photocurable 3D printing method of ceramic materials of the present invention is a low-cost, high-efficiency photocurable 3D printing method for forming large-sized ceramics and gradient ceramics. Based on the ceramic printing slurry prepared by solvent-responsive polymer resin as the base, a DLP printer is used to print and form multiple ceramic green modules. The surface of the green modules is activated by solvent stimulation, so that the ceramic green modules are welded into a whole. After degreasing and sintering processes, an integrated ceramic material with a complete structure is obtained. The preparation process is as follows Figure 2The present invention overcomes the problem that the size of light-curing 3D printed samples is limited by the size of the printer, and uses a lower-cost modular printing and construction method, which has the following advantages and beneficial effects:

[0024] 1. Breaking through the size limitations of stereolithography printers, enabling them to print across multiple sizes. Large ceramic structures can be split into multiple modules for batch printing. This allows a single stereolithography printer to print modules and produce ceramic materials that exceed its printable size range.

[0025] 2. Achieve low-cost photocuring printing of large-scale ceramic components. Since large components can be formed by splicing multiple modules, and the printed modules can be stored for a long time, a single printer can be used to print all modules multiple times, or multiple ceramic modules can be obtained in a single printing process.

[0026] 3. Achieve low-cost photocuring printing of material-gradient ceramic devices. By preparing ceramic slurries based on different ceramic powders and printing them into multiple heterogeneous modules, heterogeneous ceramics can be printed by simply replacing different ceramic slurries, eliminating the need for equipment modification and design, thus saving costs.

[0027] 4. Achieve cross-temporal collaboration in ceramic printing. Different modules of the same ceramic material can be printed at different times by printers in different locations. The printed green modules are then sealed and sent to the same location for connection, followed by debinding and sintering to create an integrated ceramic material.

[0028] 5. Improve the fault tolerance of photocurable ceramic printing. Traditional methods have a very low tolerance for printing larger ceramic materials. If a defect or equipment problem occurs during the printing process, the entire print will be scrapped. Large-scale ceramic printing is prone to problems due to its quality and size structure. Using a modular approach, only the specific printing module needs to be replaced or reset, greatly improving the fault tolerance of the printing process and correspondingly reducing printing costs.

[0029] 6. After the modules are connected together, they are degreased and sintered to obtain a ceramic material with a complete integrated structure. The connection interface is smooth and defect-free, and has a microstructure consistent with the body interface. At the same time, there is no cracking on the connection interface, and the connection strength is high.

[0030] The present invention can be used in the field of 3D printing ceramics. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Figure 1 is a diagram of the solvent welding process of the ceramic green module interface, where 1 is the first module, 2 is the second module, and 3 is n-butyl acetate.

[0032] Figure 2 This is a flow chart of modular light-curing 3D printing of ceramics, where 1 is the first module, 2 is the second module, 3 is n-butyl acetate, 4 is the 3D printer, and 5 is the 3D printed ceramic product.

[0033] Figure 3 is a scanning electron microscope photograph of the body and joints of the 3D printed ceramic prepared in Example 1;

[0034] Figure 4 This is a scanning electron microscope photograph of the joint of the 3D printed ceramic prepared in Example 2. DETAILED DESCRIPTION

[0035] The beneficial effects of the present invention are demonstrated with the following examples.

[0036] Example 1: The modular light-curing 3D printing method for single-material ceramics of this embodiment is carried out according to the following steps:

[0037] 1. Use software on a computer to split the 3D model of the target large-scale structural ceramic into two interconnected modules of the same material, where the connection surface of the two modules is a planar connection interface; and then import the 3D models of the two modules into the DLP printer separately;

[0038] 2. Preparation of ceramic slurry:

[0039] Weigh 100 g of isobornyl acrylate monomer, 3 g of polymerized isobornyl acrylate, 500 g of alumina ceramic powder, 10 g of BYK dispersant, and 0.3 g of 819 photoinitiator and add them to a ball mill and mill for 4 h to obtain the ceramic slurry for printing each module;

[0040] The preparation method of polymerized isobornyl acrylate is as follows: 0.5 g of TPO photoinitiator is added to 100 g of isobornyl acrylate, mixed evenly, and then photocured 3D printed using DLP printing to obtain polymerized isobornyl acrylate;

[0041] 3. Pour the ceramic slurry into the material tank of the DLP printer, start it, and perform light curing to print two modules to obtain the green body of the two modules;

[0042] Fourth, remove the module green body from the printing platform and clean the residual slurry on the surface of the module with water; after cleaning and drying, apply n-butyl acetate to the connection interface between the two modules, and apply pressure on both sides of the interface to make the interface close and maintain it for 5 minutes, connecting the two modules into one to obtain an integrated preform;

[0043] 5. Place the integrated preform into a sintering furnace, heat it to 120°C at a heating rate of 1°C / min and keep it for 2 hours, then heat it to 150°C and keep it for 2 hours, and finally heat it to 600°C and keep it for 1 hour for degreasing; then heat it to 1600°C and keep it for 1.5 hours before sintering to obtain 3D printed ceramics.

[0044] The 3D printed ceramic obtained in this embodiment was fractured at the module connection part and the module body part, and the microscopic interface was tested by scanning electron microscopy. The obtained scanning electron microscopy photos are as follows: Figure 3 As shown, from Figure 3 It can be seen that except for the micropores left by degreasing, no interface traces can be seen in the module connection part, proving that the interface after connection has no defects, has a dense stacking consistent with the body, and maintains a microstructure consistent with the body during the degreasing process.

[0045] Comparative Example 1: The difference between this comparative example and Example 1 is that in step 2, 3 grams of polymerized isobornyl acrylate in the ceramic slurry is replaced with 3 grams of isobornyl acrylate monomer, and the other steps and parameters are the same as those in Example 1.

[0046] The ceramic slurry prepared in this comparative example will experience severe sedimentation within 2 hours and cannot be used for ceramic printing. This is because the polymerized isobornyl acrylate is dissolved in the isobornyl acrylate monomer, and its dissolution method is that the molecular chains of the polymerized isobornyl acrylate are evenly dispersed in the monomer, thereby making the system a three-dimensional network structure. After adding ceramic powder and dispersant, a three-dimensional gel structure can be formed, which can inhibit the agglomeration and sedimentation of the ceramic powder in the system and form a stable slurry system. In this comparative example, the polymerized isobornyl acrylate is replaced with pure isobornyl acrylate monomer, which cannot form a three-dimensional network structure, resulting in severe sedimentation of the powder and cannot be used for ceramic printing.

[0047] Example 2: The modular photocuring 3D printing method for multi-material ceramics of this embodiment is carried out according to the following steps:

[0048] 1. Use software on a computer to split the 3D model of the target large-scale structural ceramic into two interconnected modules made of different materials, Module I and Module II, where the connection surface between the two modules is a planar connection interface; and then import the 3D models of the two modules into the DLP printer separately;

[0049] 2. Preparation of ceramic slurry:

[0050] Weigh 100 g of isobornyl acrylate monomer, 3 g of polymerized isobornyl acrylate, 500 g of alumina ceramic powder, 10 g of BYK dispersant, and 0.3 g of 819 photoinitiator and add them to a ball mill and mill for 4 h to obtain ceramic slurry I for printing module I;

[0051] Weigh 100 g of isobornyl acrylate monomer, 4 g of polymerized isobornyl acrylate, 450 g of alumina ceramic powder, 50 g of zirconia ceramic powder, 10 g of BYK dispersant, and 0.3 g of 819 photoinitiator and add them to a ball mill. Mill for 4 h to obtain ceramic slurry II for printing module II.

[0052] The preparation method of polymerized isobornyl acrylate is as follows: 0.5 g of TPO photoinitiator is added to 100 g of isobornyl acrylate, mixed evenly, and then photocured 3D printed using DLP printing to obtain polymerized isobornyl acrylate;

[0053] 3. Pour the ceramic slurry corresponding to each module into the material tank of the DLP printer, start it, and perform light-curing printing on each module to obtain the green body of the two modules;

[0054] 4. Remove the module green body from the printing platform and clean the residual slurry on the surface of the module with water; after cleaning and drying, apply n-butyl acetate on the connection interface between each module in the order of module I, module II, module I, and module II, and apply pressure on both sides of the interface and maintain it for 5 to 10 minutes to connect the four modules into one to obtain an integrated preform;

[0055] 5. Place the integrated preform into a sintering furnace, heat it to 120°C at a heating rate of 1°C / min and keep it for 2 hours, then heat it to 150°C and keep it for 2 hours, and finally heat it to 600°C and keep it for 1 hour for degreasing; then heat it to 1600°C and keep it for 1.5 hours before sintering to obtain 3D printed ceramics.

[0056] The 3D printed ceramic of this embodiment was fractured and the connection surface was tested by scanning electron microscopy. The obtained SEM image is as follows: Figure 4 As shown, the red line in the figure is the connection surface, the low-magnification SEM picture of the first connection surface from left to right is A, and the high-magnification SEM picture is B; the low-magnification SEM picture of the second connection surface from left to right is C, and the high-magnification SEM picture is D, and the Figure 4 It can be seen that the powders at the connection interface are densely packed without any defects different from those at the internal interface, which proves that the ceramic after solvent welding in this embodiment is intact.

[0057] The present invention uses a photocurable ceramic printing slurry composed of different ceramic powders. This slurry is printed into multiple ceramic green body modules using a DLP printer. These modules are then assembled and connected together using a solvent welding method to form a single-material or multi-material gradient preform. The preform is then degreased and sintered to produce a complete ceramic. This means that multiple small ceramic green bodies are used as building blocks to create a large-volume single-material or multi-material gradient green body, which is then degreased and sintered to form a large-volume complete ceramic.

Claims

1. A modular light-curing 3D printing method for ceramics, characterized in that The method proceeds as follows:

1. Use software on a computer to split the 3D model of the target large-scale structural ceramic into interconnected modules of the same material, or into interconnected modules with gradient material changes, where the connection surfaces of each module are planar connection interfaces; and then import the 3D models of each module into a DLP printer; 2. Prepare ceramic slurry: Weigh acrylate monomer, polymerized acrylate, ceramic powder, dispersant, and photoinitiator and add them to a ball mill and mix evenly to obtain ceramic slurry for printing each module; The mass of the polymerized acrylate is 3% to 15% of the mass of the acrylate monomer; 3. Pour the ceramic slurry corresponding to each module into the material tank of the DLP printer, start it, and perform light-curing printing on each module to obtain a green body of multiple modules; Fourth, remove the module green body from the printing platform and clean the residual slurry on the surface of the module with water; after cleaning and drying, apply n-butyl acetate to the connection interface between the modules, and apply pressure on both sides of the interface and maintain it for 10 to 30 minutes. The multiple modules are connected into one to obtain an integrated preform; 5. Place the integrated preform into a sintering furnace, heat it to 120-125°C at a heating rate of 0.2-2°C / min and keep it warm for 2-5 hours, then heat it to 150-155°C and keep it warm for 2-5 hours, and finally heat it to 600-620°C and keep it warm for 2-5 hours for degreasing; then sinter it at high temperature to obtain 3D printed ceramics.

2. A modular light-curing 3D printing ceramic method according to claim 1, characterized in that: The acrylic acid ester monomer described in step 1 is one or a combination of isobornyl acrylate, isobornyl methacrylate, neobornyl acrylate, neobornyl methacrylate and isobornyl diester acrylate.

3. A modular light-curing 3D printing ceramic method according to claim 1 or 2, characterized in that: The preparation method of the polymerized acrylate described in step 1 is: adding a photoinitiator accounting for 0.3% to 8% by mass of the acrylate monomer to the acrylate monomer, mixing evenly, and performing light-curing 3D printing with a DLP printer to obtain the polymerized acrylate.

4. A modular light-curing 3D printing ceramic method according to claim 1 or 2, characterized in that: The module is made of the same material as described in step 1, and the ceramic powder in the ceramic slurry used to prepare the module is alumina ceramic powder or zirconia ceramic powder.

5. A modular light-curing 3D printing ceramic method according to claim 1 or 2, characterized in that: The ceramic powder in the ceramic slurry for preparing the module with a gradient material change described in step 1 is prepared in the order of module connection. Starting from the second module, the ceramic powder in the ceramic slurry of the subsequent module is replaced by a different type of ceramic powder at 5% to 10% of its mass.

6. A modular light-curing 3D printing ceramic method according to claim 1 or 2, characterized in that: The dispersant described in step 2 is dispersant BYK.

7. A modular light-curing 3D printing ceramic method according to claim 1 or 2, characterized in that: The photoinitiator described in step 2 is 819 or TPO photoinitiator.

8. A modular light-curing 3D printing ceramic method according to claim 1 or 2, characterized in that: The mass of the dispersant described in step 2 is 1% to 5% of the mass of the ceramic powder.

9. A modular light-curing 3D printing ceramic method according to claim 1 or 2, characterized in that: The mass of the photoinitiator described in step 2 is 0.3% to 8% of the sum of the mass of the acrylate monomer and the polymerized acrylate.

10. A modular light-curing 3D printing ceramic method according to claim 1 or 2, characterized in that: The volume of the ceramic powder in step 2 is 40% to 50% of the total volume of the mixed ceramic slurry.

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