A hierarchical porous parts forming method based on additive manufacturing / high-temperature self-propagation

Abstract

The present invention discloses a method for forming hierarchical porous parts based on additive manufacturing / high-temperature self-propagation. A method for preparing hierarchical porous materials, comprising the following steps: using three-dimensional modeling software to model the hierarchical porous material, using slicing software to perform layered processing on the hierarchical porous material model to generate a printing trajectory of the material, and importing it into an adhesive jet printing device; mixing the raw material powders of the hierarchical porous material, placing it in an adhesive jet printing device, and printing it into a green body; curing the green body; after curing, using a laser to heat the body to induce a high-temperature self-propagation reaction, and obtaining a hierarchical porous material after the reaction. The method provided by the present invention can produce parts with complex structures or large sizes, save costs, shorten the manufacturing process and production cycle of hierarchical porous materials, and improve production quality and production efficiency.

Description

Technical Field

[0001] The present invention relates to the field of material processing technology, and in particular to a hierarchical porous part forming method based on additive manufacturing / high-temperature self-propagation. Background Art

[0002] Hierarchical porous ceramics not only possess the advantages of conventional ceramics, such as high chemical stability, high temperature resistance, corrosion resistance, and high strength, but also boast lightweight, high specific strength, high specific stiffness, and multifunctional integration. They are widely used in numerous fields, including chemical engineering, medical treatment, and aerospace. These ceramic parts significantly enhance lightweighting, providing novel and efficient materials for achieving higher-performance, high-end products. However, existing technologies for manufacturing hierarchical porous ceramics are complex, require long production cycles, and are unable to produce complex structures or large-scale products. Summary of the Invention

[0003] In order to overcome the problems of complex manufacturing process and long production cycle of hierarchical porous ceramics in the prior art, the purpose of the present invention is to provide a method for preparing hierarchical porous parts.

[0004] The present invention provides a method for preparing a hierarchical porous part, comprising the following steps:

[0005] (1) Using 3D modeling software to design a porous part model with multi-scale gradient connected pores, using slicing software to perform layered processing on the porous part model, generating the inkjet trajectory of the nozzle, and importing it into the adhesive jet printing device;

[0006] (2) using at least two powders selected from metal element powder, non-metal element powder, and ceramic powder capable of generating an exothermic reaction as raw material powders for the hierarchical porous part, mixing the raw material powders to obtain a mixed powder, using a photosensitive resin as an adhesive, setting printing parameters of an adhesive jet printing device, forming a green body comprising the mixed powder and the adhesive, and drying the green body;

[0007] (3) The dried green body is ignited by external energy supply, so that a high-temperature self-propagating reaction occurs between the different powder materials in the green body. The mixed powder reacts in situ at high temperature to produce a new ceramic phase and continuously releases heat. During the reaction, randomly distributed micropores are generated inside and / or on the surface of the green body to obtain the hierarchical porous part.

[0008] Preferably, the porosity of the hierarchical porous part is 20%-50%; the hierarchical porous part has holes designed and manufactured by adhesive injection, and many smaller holes formed by high-temperature self-propagation treatment are distributed on the surface of these holes.

[0009] Preferably, in the method for preparing the hierarchical porous parts, in step (1), the layer thickness of the layered treatment is set to 80-150 μm; the layer thickness parameter setting of the layered treatment should be greater than the maximum particle size of each powder in the raw material powder.

[0010] Preferably, in the method for preparing the hierarchical porous parts, in step (2), the raw material powder should be suitable for the adhesive jet printing device, have a particle size of 5-80 μm, and a sphericity of >95%.

[0011] Preferably, in the method for preparing the hierarchical porous parts, in step (2), the metal element powder includes at least one of titanium, aluminum, silver, iron, calcium, manganese, copper, and gold powder.

[0012] Preferably, in the method for preparing the hierarchical porous parts, in step (2), the non-metallic elemental powder comprises at least one of carbon, silicon, boron, phosphorus, and sulfur powder.

[0013] Preferably, in the method for preparing the hierarchical porous parts, in step (2), the ceramic powder includes at least one of intermetallic compounds, carbides, nitrides, borides, silicides, and ceramic-based composite material powders.

[0014] Further preferably, in step (2), the raw material powder includes Al powder, ZrO2 powder, and Ag powder; still further preferably, the mass ratio of Al powder, ZrO2 powder, and Ag powder is (5-9):(1.5-2):1; further preferably, the mass ratio of Al powder, ZrO2 powder, and Ag powder is (6-8):(1.5-2):1.

[0015] Further preferably, in step (2), the raw material powder includes Si powder, C powder, and Ag powder; still further preferably, the mass ratio of Si powder, C powder, and Ag powder is (1.2-2.4): (2-2.6): 1; further preferably, the mass ratio of Si powder, C powder, and Ag powder is (1.6-2): (2-2.6): 1.

[0016] Preferably, in the method for preparing the hierarchical porous parts, in step (2), the adhesive comprises 1,6-hexanediol diacrylate, tricyclodecane dimethanol diacrylate, and a photoinitiator.

[0017] Further preferably, the adhesive used in the adhesive jet printing device contains 20 wt % to 50 wt % of 1,6-hexanediol diacrylate, 10 wt % to 30 wt % of tricyclodecane dimethanol diacrylate, and 5 wt % to 20 wt % of a photoinitiator.

[0018] Preferably, in the method for preparing such hierarchical porous parts, in step (2), a light source is used to irradiate the printed layer during the printing process; further preferably, the light source is an ultraviolet light source, and the use of ultraviolet light irradiation can accelerate the curing and molding of the printing process.

[0019] Preferably, in the preparation method of the hierarchical porous parts, in step (2), the drying treatment is specifically: drying the green body at 100-250°C for 0.5-3h; further preferably, the drying treatment is specifically: drying the green body at 150-200°C for 1.5-2.5h.

[0020] Preferably, in the preparation method of this hierarchical porous part, in step (3), the ignition treatment method is one of combustion wave ignition, radiation flow ignition, laser ignition, spark ignition, heating gas ignition, chemical ignition, electric heat ignition, microwave energy ignition, and thermal explosion of linear heating.

[0021] In some preferred embodiments of the present invention, a fiber laser is used to heat the blank to induce a high-temperature self-propagating reaction. An external heat source is then used to induce the high-temperature self-propagating reaction at a specific location within the blank within a defined reaction environment. This self-propagating reaction generates a large amount of heat to drive subsequent reactions, allowing reactants that participate in the self-propagating reaction to be synthesized in situ to produce the target product. Compared to sintering in a resistance furnace, the entire process is completed instantaneously. During the self-propagating reaction, the residual binder within the blank is converted into a non-toxic and harmless gaseous substance during the combustion reaction, creating a large number of pores within the product. This creates a material with two different pore sizes, resulting in the hierarchical porous part.

[0022] Further preferably, the fiber laser irradiation time is 1-5 seconds; after starting the fiber laser irradiation, the fiber laser is turned off to allow the blank to undergo a self-propagating reaction.

[0023] The beneficial effects of the present invention are:

[0024] 1. The method for preparing hierarchical porous parts provided by the present invention can better prepare porous parts. This method uses adhesive jetting additive manufacturing technology to prepare the green body of the hierarchical porous structure parts. While having the advantages of additive manufacturing technology, compared with other powder bed additive manufacturing technologies, it avoids direct melting of powder. The adhesive in the green body provides the basis for the subsequent emergence of porous structure. This method uses a high-temperature self-propagating post-processing method to form parts with higher porosity and larger specific surface area. Compared with the closed small pores formed during the sintering densification process, it has better functionality.

[0025] 2. The method for preparing hierarchical porous parts provided by the present invention can effectively shorten the manufacturing process and production cycle. Compared to tape casting, the method of the present invention does not require sintering in a high-temperature atmosphere, which can shorten the production cycle. Furthermore, the method can perform preliminary solidification of the green body during the adhesive injection stage. Compared to slip casting, there is no need to wait for the solvent in the slurry to dry, which significantly shortens the production cycle.

[0026] 3. The method for preparing hierarchical porous parts provided by this invention can produce parts with complex structures or large dimensions. During the green body forming stage, the method provided by this invention is free from mold constraints and the platform does not require atmosphere protection, making it possible to produce green bodies with relatively complex structures and large dimensions. During the high-temperature self-propagating synthesis stage, the effect can be controlled by adjusting the spot size, laser power, and loading time.

[0027] 4. The method for preparing hierarchical porous parts provided by this invention can save costs. The hierarchical porous ceramic parts are prepared using in-situ synthesis, using powders that can be generated by in-situ synthesis reactions as raw materials, thereby reducing raw material costs. The high-temperature self-propagating synthesis method is characterized by utilizing the heat released by the highly exothermic chemical reaction to allow the chemical reaction to continue spontaneously after "ignition" without the need for an external heat source, thus saving energy costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is an implementation flow chart of the present invention.

[0029] Figure 2 Schematic diagram of the hierarchical porous structure of the SiC-Ag gas filter prepared in Example 2. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below by way of specific examples. The description of the examples is intended only to facilitate understanding of the present invention and is not intended to limit the protection of the present invention. The materials and reagents used in the examples, unless otherwise specified, are commercially available.

[0031] In the present embodiment, a planetary ball mill is used to mix the reactant powders into a uniform material.

[0032] The adhesive spraying equipment used in the present invention adopts the LA-3DP-300 independently developed by South China University of Technology. The equipment consists of a powder cart, a powder supply cylinder, a forming cylinder, a powder spreading roller, a UVLED light source, a nozzle, a controller, and a host computer. The pre-printed product model is loaded into the host computer, and evenly mixed powder is placed in the powder supply cylinder. When the equipment is started, it can automatically spread powder layer by layer and spray ink and light-cure at predetermined positions, finally forming a preliminary three-dimensional object.

[0033] In the present invention, an N41 / H muffle furnace is used to dry the rough blank.

[0034] The present invention example uses MFMC-6000W-20000W multi-mode continuous fiber laser as the laser light source "ignition".

[0035] As attached Figure 1 As shown, the method for preparing the hierarchical porous material provided by the present invention specifically includes the following steps:

[0036] (a) Use 3D modeling software to model a porous part. The part has interconnected pores. Microstructurally, the pore surface is dotted with even smaller holes, indicating that the part has a hierarchical porous structure. Slicing software is then used to layer the model, presetting the layer thickness and dividing the model into several 2D shapes. This generates a print path for the part, which is then imported into the host computer of the adhesive jetting equipment.

[0037] (b) selecting as the raw material powder at least one metal element powder, at least one non-metal element powder, or a ceramic powder capable of producing an exothermic reaction at high temperature. Adjusting the ball milling speed and time to uniformly mix the raw material powders, and selecting as the adhesive a resin adhesive that can be sintered and removed at high temperature without residue.

[0038] (c) Place a substrate with a clean and smooth surface on the molding cavity. Place the evenly mixed raw material powder in the powder cylinder of the adhesive jet additive manufacturing equipment, set the equipment's layer thickness, scanning speed, adhesive saturation, curing time, curing power, curing times, printing direction, scanning strategy and other process parameters, and print it into a porous part green body. First, the powder-laying roller spreads the powder according to the preset layer thickness, and the nozzle sprays the adhesive according to the printing track in step (a) to bond the metal powder and ceramic powder of the current printing layer. The current printing layer is irradiated by the light source module to preliminarily solidify the bonding area. The light source module can use an ultraviolet light source;

[0039] (d) Repeat the powder spreading, bonding and curing steps until a porous green body of the part is formed; place the green body together with the substrate into a muffle furnace, set the drying temperature and time, and perform drying and further curing. After the heating and drying process is completed, cool it down with the furnace until the temperature in the muffle furnace cavity is slightly higher than room temperature, remove the substrate, and place it in the air to continue cooling. When the temperature of the substrate drops to slightly higher than room temperature, remove the dried green body;

[0040] (e) igniting the green body dried in step (d) to perform high-temperature self-propagating synthesis. The green body is placed on a high-temperature resistant substrate under a laser. The laser power, loading time, height and other process parameters are set. The laser locally heats the green body, inducing the powder capable of synthesizing ceramics to undergo a chemical reaction at high temperature to synthesize the ceramic in situ and continuously release heat, so that the energy is maintained throughout the green body.

[0041] (f) When the adhesive is sintered at a high temperature and the gas generated by the reaction overflows, the surface of the holes designed and manufactured inside the part produces smaller holes, forming hierarchical pores with different sizes, thereby obtaining the hierarchical porous ceramic part.

[0042] Example 1

[0043] A method for preparing an Al2O3-ZrO2-Ag antenna, mainly used in the field of antennas, includes the following steps:

[0044] Step 1: Use 3D modeling software to model the hierarchical porous ceramic part. The porosity of the part is designed to be 25%. The size of the part is 10mm*10mm*5mm.

[0045] Step 2: Use slicing software to layer the part model with a layer thickness of 100 μm, generate the part's printing trajectory, and import it into the host computer of the adhesive jetting equipment.

[0046] Step 3: Select pure Al powder and ZrO2 powder with a particle size of 15-53μm, and pure Ag powder with a particle size of 38-58μm, and configure them according to the mass ratio of Al:ZrO2:Ag=7:1.8:1. After ball milling and screening, they are made into raw material powder with uniform particle size. The ball powder mass ratio during ball milling is 4:1, the ball milling time is 2h, and the ball milling speed is 400rpm.

[0047] Step 4: Place the evenly mixed Al, ZrO2, and Ag powders in the powder tank of the binder jet additive manufacturing equipment, level the substrate, set the equipment's process parameters such as layer thickness, scanning speed, binder saturation, curing time, curing power, number of curing times, printing direction, and scanning strategy, and print the green body.

[0048] Step 5: Place the green body in a muffle furnace, heat to 200°C, and hold at this temperature for 2 hours. The dried green body undergoes post-processing using laser high-temperature self-propagating synthesis. Place the dried green body on a high-temperature resistant substrate. Adjust the laser output spot to face the top surface of the green body perpendicularly, with a spot size of 15 mm. Open the argon protection valve. Start the fiber laser with a laser power of 700 W and a laser irradiation time of 1 second. Then turn off the laser to allow a self-propagating reaction to occur. After the reaction is complete, cool the sample to room temperature under argon protection to obtain an Al2O3-ZrO2-Ag hierarchical porous ceramic component, which can effectively reduce the size of the antenna.

[0049] Example 2

[0050] A method for preparing a SiC-Ag high-temperature gas filter, mainly used in filtering devices for high-temperature toxic gases, includes the following steps:

[0051] Step 1: Use 3D modeling software to model the hierarchical porous ceramic part. The porosity of the part is designed to be 30%. The size of the part is 50mm*10mm*50mm.

[0052] Step 2: Use slicing software to layer the part model with a layer thickness of 150 μm, generate the printing trajectory of the part, and import it into the host computer of the adhesive injection equipment.

[0053] Step 3: Select pure Si powder and graphite powder with a powder particle size of 25-62μm, and pure Ag powder with a particle size of 38-58μm, and configure them according to the mass ratio of Si:C:Ag = 1.8:2.3:1. After ball milling and screening, they are made into raw material powder with uniform particle size. The ball powder mass ratio during ball milling is 4:1, the ball milling time is 2h, and the ball milling speed is 300rpm to ensure that they are fully mixed.

[0054] Step 4: Place the evenly mixed Si:C:Ag powder in the powder tank of the binder jet additive manufacturing equipment, level the substrate, set the equipment's process parameters such as layer thickness, scanning speed, binder saturation, curing time, curing power, number of curing times, printing direction, and scanning strategy, and print the green body.

[0055] Step 5: Place the green body in a muffle furnace, heat to 150°C, and keep warm for 2 hours. Perform high-temperature self-propagating synthesis post-treatment on the dried green body. Place the dried rough body on a high-temperature resistant substrate, adjust the laser output spot vertically facing the upper surface of the rough body, with a spot diameter of 10mm, and open the argon protection valve; start the fiber laser with a laser power of 800W and a laser irradiation time of 2s, then turn off the laser to allow a self-propagating reaction to occur; after the reaction is completed, the sample is cooled to room temperature under argon protection to obtain a SiC-Ag high-temperature gas filter device. Its hierarchical porous structure can better filter exhaust gas.

[0056] The hierarchical porous structure of the SiC-Ag high temperature gas filter prepared in this embodiment is as follows: Figure 2 As shown in the figure, it can be seen that the part has a gradient connecting hole with a pore size ranging from 1.1mm to 1.5mm, and there are many pits and tiny holes distributed on the pillars of the gradient connecting hole, which makes the part have a larger specific surface area and can better play the role of filtering high-temperature gas.

[0057] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing a hierarchical porous part, characterized in that: The following steps are involved: (1) Using 3D modeling software to design a porous part model with multi-scale gradient connected pores, using slicing software to perform layered processing on the porous part model, generating the inkjet trajectory of the nozzle, and importing it into the adhesive jet printing device; (2) using at least two powders selected from metal element powder, non-metal element powder, and ceramic powder capable of generating an exothermic reaction as raw material powders for the hierarchical porous part, mixing the raw material powders to obtain a mixed powder, using a photosensitive resin as an adhesive, setting printing parameters of an adhesive jet printing device, forming a green body comprising the mixed powder and the adhesive, and drying the green body; (3) igniting the dried green body by external energy supply, so that a high-temperature self-propagating reaction occurs between different powder materials in the green body, and the mixed powder reacts in situ at high temperature to produce a new ceramic phase and continuously releases heat. During the reaction, randomly distributed micropores are generated inside and / or on the surface of the green body, thereby obtaining the hierarchical porous part; In step (2), the raw material powders are Al powder, ZrO2 powder and Ag powder in a mass ratio of (5-9): (1.5-2): 1, or the raw material powders are Si powder, C powder and Ag powder in a mass ratio of (1.2-2.4): (2-2.6):

1.

2. The method for preparing a hierarchical porous part according to claim 1, characterized in that: The porosity of the hierarchical porous part is 20%-50%.

3. The method for preparing a hierarchical porous part according to claim 1, wherein: In step (1), the layer thickness set by the layering process is 80-150 μm.

4. The method for preparing a hierarchical porous part according to claim 1, wherein: In step (2), the particle size of the raw material powder is 5-80 μm, and the sphericity is greater than 95%.

5. The method for preparing a hierarchical porous part according to claim 1, characterized in that: In step (2), the adhesive comprises 1,6-hexanediol diacrylate, tricyclodecane dimethanol diacrylate, and a photoinitiator.

6. The method for preparing a hierarchical porous part according to claim 5, characterized in that: The adhesive comprises 20 wt % to 50 wt % of 1,6-hexanediol diacrylate, 10 wt % to 30 wt % of tricyclodecane dimethanol diacrylate, and 5 wt % to 20 wt % of a photoinitiator.

7. The method for preparing a hierarchical porous part according to claim 1, characterized in that: In the step (2), the drying process is specifically as follows: drying the green body at 100-250° C. for 0.5-3 h.

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