Modular photocuring 3D ceramic printing method

Abstract

The invention discloses a modular photocuring 3D ceramic printing method, and relates to a 3D printing method of photocuring ceramic. The method aims at solving the problem that block 3D printing of ceramic parts cannot be achieved through an existing method, and comprises the steps that after a 3D model of target large-size structural ceramic is split into mutually-connected modules through software on a computer, the 3D model is imported into a DLP printer; secondly, DLP printing is conducted through ceramic slurry corresponding to all the modules to obtain all the modules, after all the modules are cleaned and aired, connection interfaces between all the modules are coated with n-butyl acetate, pressure is applied to enable the modules to be connected into a whole, and an integrated prefabricated blank is obtained; and performing degreasing and high-temperature sintering to obtain the 3D printing ceramic. The obtained ceramic connecting interface is free of defects and has a microstructure consistent with a body interface, meanwhile, the connecting interface is free of cracks, and the method can be used for the field of 3D printing ceramic.

Description

Technical Field

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

[0002] Ceramics are an indispensable material in the current human daily life and social production and construction process. Along with the application of ceramic materials in many fields, there is an increasing demand for ceramic materials of various sizes with complex geometric shapes and multiple materials. Compared with traditional manufacturing technology, 3D printing technology, due to its layer-by-layer manufacturing method of building materials, can flexibly and efficiently build complex and precise structures without relying on molds, and fully improve the degree of design freedom, and has the potential to subvert the entire ceramic manufacturing industry.

[0003] At present, for larger-sized 3D printed parts, a block printing method can be used. For example, the Chinese patent "Sanitary ceramic mold forming method based on three-dimensional printing technology" with application number CN201610497849.3 discloses a method of first dividing the 3D model into blocks through a three-dimensional printer, and then printing the blocks; then polishing and smoothing all the parts one by one, and then using adhesives to bond and assemble them into a plastic solid model, and then batch-producing to obtain a sanitary ceramic mold. The Chinese patent "Method for 3D printing large sculpture models" with application number 201711153154.4 discloses a method of first using ordinary printing equipment to print thin models in blocks, and then bonding and assembling the assembly surfaces with slow-drying resin glue. However, the existing methods that rely on adhesives cannot achieve block 3D printing of ceramic parts, because the printed parts (green bodies) of ceramic parts need to go through 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 body will decompose due to heat during the degreasing and sintering process, causing the assembly interface to separate, and thus it is impossible to obtain an integrated ceramic material. Summary of the invention

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

[0005] The modular photocuring 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-size structural ceramic into interconnected modules of the same material, or into interconnected modules with gradient-changing materials, where the connection surfaces of each module are planar connection interfaces; and 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 into a ball mill and mix them evenly to obtain ceramic slurry for printing each module; wherein the mass of polymerized acrylate is 3% to 15% of the mass of acrylate monomer;

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

[0009] Fourth, remove the module green body on 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 the modules, and apply pressure on both sides of the interface and maintain for 10 to 30 minutes, so that multiple modules are connected as 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 for 2-5 hours, then heat it to 150-155°C and keep it for 2-5 hours, and finally heat it to 600-620°C and keep it for 2-5 hours for degreasing; then sinter it at high temperature to obtain 3D printed ceramics.

[0011] Furthermore, 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.

[0012] Furthermore, the preparation method of the polymerized acrylate described in step 1 is: adding a photoinitiator accounting for 0.3% to 8% of the 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, wherein the ceramic powder is alumina ceramic powder or zirconia ceramic powder.

[0014] Furthermore, for the module with a gradient material change described in step 1, the ceramic powder in the ceramic slurry for preparing the module is replaced by a different type of ceramic powder in the ceramic slurry of the second module according to the connection order of the modules. The ceramic powder in the ceramic slurry of the subsequent module is replaced by 5% to 10% of the mass of the ceramic powder in the ceramic slurry of the previous module. In the module thus formed, the newly added ceramic powder presents a gradient change.

[0015] Furthermore, in the ceramic slurry of the modules with a gradient material change, 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 obtained by replacing the alumina ceramic powder in the ceramic slurry of the previous module 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 20 μL to 30 μL per square centimeter; the connection interface of the stimulation module is infiltrated with n-butyl acetate, and due to the extremely strong solubility of n-butyl acetate solvent for polymerized acrylate, the polymerized acrylate molecular chains at the interface are disentangled, and a gel layer structure with a certain fluidity is formed at the interface. Under external pressure, the two gel layers at the connection interface diffuse with each other, and 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 ceramic material method of the present invention is a low-cost, high-efficiency photocurable 3D printing method for forming large-size ceramics and gradient ceramics. Based on a ceramic printing slurry prepared by a solvent-responsive polymer resin as a substrate, a DLP printer is used to print and form multiple ceramic green modules, and the surface of the green module is activated by solvent stimulation, so that the ceramic green modules are welded as a whole, and 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 the photocurable 3D printed sample 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 limitation of photocuring printers, making them capable of cross-size printing. Large-size ceramic structures can be split into multiple modules for batch printing, so that a photocuring printer can prepare ceramic materials that exceed its printing size range by printing modules.

[0025] 2. Realize low-cost photocuring printing of large-size ceramic devices. Since large devices can be spliced ​​and formed by multiple modules, and the printed modules can be stored for a long time, one printer can be used to print all modules multiple times, or multiple ceramic modules can be obtained in one printing process.

[0026] 3. Realize 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, the printing of heterogeneous ceramics can be achieved by simply replacing different ceramic slurries, without the need for equipment modification and design, thus saving costs.

[0027] 4. Realize the cross-time and space cooperation capability of ceramic printing. Different modules of the same ceramic material can be printed by printers distributed in different locations at different times, and then the printed green modules are sealed and stored and sent to the same place for connection, followed by degreasing and sintering to obtain an integrated ceramic material.

[0028] 5. Improve the fault tolerance of ceramic photocuring printing. The traditional method has a very low fault tolerance rate for printing larger ceramic materials. Once defects or equipment problems occur during the printing process, the entire print will be scrapped. Large-size ceramic printing is prone to problems due to its quality and size structure. With the modular method, only the specific printing module needs to be replaced or reset, which greatly improves the fault tolerance of the printing process and reduces the printing cost accordingly.

[0029] 6. After the modules are connected together, degreasing and sintering are performed 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 interface of the main body. At the same time, there is no cracking on the connection interface, and the connection strength is high.

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

[0031] Figure 1 This is a diagram of the solvent welding process of the ceramic green body 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 photocuring 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 connection of the 3D printed ceramic prepared in Example 2. DETAILED DESCRIPTION

[0035] The beneficial effects of the present invention are verified by the following examples.

[0036] Embodiment 1: The modular photocuring 3D printing method of a single-material ceramic of this embodiment is carried out according to the following steps:, including the following steps:

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

[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 dispersant BYK, and 0.3 g of 819 photoinitiator and add them to a ball mill and mill for 4 h to obtain 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, the mixture is evenly mixed, and then photocured 3D printing is performed using DLP printing to obtain polymerized isobornyl acrylate;

[0041] 3. Inject the ceramic slurry into the material tank of the DLP printer, start it, and perform photocuring printing on two modules to obtain green bodies of the two modules;

[0042] Fourth, remove the module green body on 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 the two modules, and apply pressure on both sides of the interface to make the interface close and keep it for 5 minutes, connect the two modules into one, and 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 for 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 microscope. The scanning electron microscope photos obtained 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, which proves that the interface after connection has no defects, has a dense stacking consistent with the main body, and maintains a microstructure consistent with the main 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 undergo 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 the dissolution method is that the molecular chain of the polymerized isobornyl acrylate is evenly dispersed in the monomer, so that the system becomes 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 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, and a three-dimensional network structure cannot be formed, resulting in severe sedimentation of the powder, which cannot be used for ceramic printing.

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

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

[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 dispersant BYK, and 0.3 g of 819 photoinitiator, add them into a ball mill and mill for 4 h to obtain ceramic slurry I of printing module I;

[0051] Weigh 100 g of isobornyl acrylate monomer, 4 g of polymerized isobornyl acrylate, 450 g of alumina ceramic powder and 50 g of zirconium oxide ceramic powder, 10 g of dispersant BYK, and 0.3 g of 819 photoinitiator, add them into a ball mill, and ball 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, the mixture is evenly mixed, and then photocured 3D printing is performed using DLP printing to obtain polymerized isobornyl acrylate;

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

[0054] Fourth, remove the module green body on 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 for sintering to obtain 3D printed ceramics.

[0056] The 3D printed ceramic of this embodiment was fractured, and a scanning electron microscope test was performed on the connection surface to obtain the SEM image as shown in FIG. Figure 4 As shown, the red line in the figure is the connection surface. From left to right, the low-magnification SEM image of the first connection surface is A, and the high-magnification SEM image is B; from left to right, the low-magnification SEM image of the second connection surface is C, and the high-magnification SEM image is D. 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 is based on a ceramic photocurable printing slurry composed of different ceramic powders, and uses a DLP printer to print and shape multiple ceramic green body modules using the ceramic slurry; the multiple ceramic green body modules are combined in a manner, and the interfaces are connected as a whole by a solvent welding method to obtain a single material or heterogeneous material gradient preform; the preform is degreased and sintered to obtain a complete ceramic. That is, multiple small-volume ceramic green bodies are used as building modules to make large-volume ceramic single-material or multi-material gradient green bodies, and degreased and sintered to obtain large-volume complete ceramics.

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-size structural ceramic into interconnected modules of the same material, or into interconnected modules with gradient-changing materials, where the connection surfaces of each module are planar connection interfaces; and 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 into a ball mill and mix them 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. Inject the ceramic slurry corresponding to each module into the material tank of the DLP printer, start it, and perform photocuring printing on each module to obtain a green body of multiple modules; Fourth, remove the module green body on 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 the modules, and apply pressure on both sides of the interface and maintain for 10 to 30 minutes, so that multiple modules are connected as 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 for 2-5 hours, then heat it to 150-155°C and keep it for 2-5 hours, and finally heat it to 600-620°C and keep it 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% of the 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.

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 for preparing 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: For the module with gradient material change described in step 1, the ceramic powder in the ceramic slurry for preparing the module 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 obtained by replacing 5% to 10% of the mass of the ceramic powder in the ceramic slurry of the previous module with a different type of ceramic powder.

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 ceramic slurry after mixing.

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