Densification pretreatment method for photocuring 3D printing silver component
By degreasing the green body of the photocured 3D printed silver component, filling the gaps with a saturated silver salt solution under vacuum and decomposing it at high temperature, the problem of low density of photocured 3D printed silver components was solved, achieving efficient densification and improving plasticity and toughness.
Patent Information
- Application Number
- CN202511323563.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-16
- Publication Date
- 2025-12-19
AI Technical Summary
In existing technologies, photopolymer 3D printed silver components have low density after sintering, resulting in low plasticity and toughness. Furthermore, hot isostatic pressing (HIP) sintering methods are expensive, time-consuming, and require high density of the initial sample.
After degreasing the 3D printed silver component preform, it is immersed in a saturated silver salt solution under vacuum to fill the internal voids. The silver salt is then decomposed into silver or silver oxide at high temperature to increase the particle contact area and reduce porosity.
It significantly improves the sintering density of silver components, enhances plasticity and toughness, simplifies the processing, reduces costs and time, and is suitable for different initial sample densities.
Smart Images
Figure CN121156291A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of 3D printing technology, and specifically to a densification pretreatment method for photopolymerization 3D printed silver components. Background Technology
[0002] Photopolymer 3D printing of silver components involves encapsulating solid silver powder particles in photosensitive resin, then curing the resin through directional exposure, shaping the silver powder and the resulting preform. To obtain pure silver components, the cured preform requires heat treatment. Heat treatment is a crucial step in photopolymer 3D printing of silver components; after this step, the silver component can be sintered and formed.
[0003] However, during the sintering process, numerous pores appear inside the silver component. After sintering, these pores are sealed inside, resulting in low density and consequently, low plasticity and toughness. This drawback is not unique to photopolymer 3D printing of silver components; it is also prevalent in other metal or ceramic photopolymer 3D printing technologies.
[0004] Currently, the problem is often solved using hot isostatic pressing (HIP). This method requires expensive equipment, has a long heat treatment cycle, and places certain requirements on the density of the initial sample; if the density is below a certain level, the method is ineffective. Therefore, this method cannot meet practical needs.
[0005] It should be noted that this section is intended to provide background or context for the embodiments of this disclosure set forth in the claims. The description herein does not constitute an admission that it is prior art simply because it is included in this section. Summary of the Invention
[0006] This invention provides a method for preparing photopolymer 3D printed silver components, which solves the problems of high processing costs, long processing cycles, and certain requirements on the density of the initial sample in the prior art that uses hot isostatic pressing to improve the density of silver components after sintering.
[0007] This invention provides a method for preparing photopolymerizable 3D printed silver components, comprising:
[0008] Silver component preforms were prepared from silver-containing photosensitive materials using photopolymerization 3D printing technology. The silver component preforms were then degreased to obtain degreased silver component samples.
[0009] The degreased sample of the silver component was immersed in a saturated silver salt solution under vacuum. After maintaining the vacuum state for a certain period of time, it was taken out, cleaned and dried, and then subjected to heat treatment to obtain the initial sample of the silver component.
[0010] The initial sample of the silver component was sintered to obtain the silver component.
[0011] Preferably, the silver powder content in the silver-containing photosensitive material is 70-90% by mass.
[0012] Preferably, the step of obtaining the initial sample of the silver component includes:
[0013] The degreased sample of the silver component was placed in a vacuum chamber, and after evacuation, a saturated silver salt solution at room temperature was injected until it completely covered the degreased sample of the silver component.
[0014] Stop injecting the saturated silver salt solution, evacuate again and hold for at least 1 minute, then remove, clean and dry, then heat to a preset temperature and hold for a preset time to obtain the initial sample of the silver component.
[0015] Preferably, the vacuum level after both evacuations is 10. -5 ~10 -6 Pa.
[0016] Preferably, the preset temperature is 400-500℃ and the preset time is 10-30min.
[0017] The method for preparing photopolymer 3D printed silver components provided in this invention involves degreasing the silver component preform, filling the internal voids of the silver component before the sintering neck is formed using a saturated silver salt solution under vacuum, and then using high temperature to decompose the silver salt into silver or silver oxide. This increases the contact area of the internal particles of the silver component, reduces the porosity, lowers the driving force for dense sintering, significantly improves the sintering density of the final sintered silver component, and effectively improves the plasticity and toughness of the silver component.
[0018] This method is simple to prepare, has a short processing cycle, is inexpensive, and does not require high initial sample density, thus effectively meeting practical needs. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of the heat treatment process for photopolymer 3D printed silver components in existing technology;
[0021] Figure 2 A flowchart illustrating the implementation of a method for preparing a photopolymer 3D printed silver component according to an embodiment of the present invention;
[0022] Figure 3This is a scanning electron microscope (SEM) schematic diagram of the silver component 1 in Embodiment 1 of the present invention;
[0023] Figure 4 This is a scanning electron microscope (SEM) schematic diagram of the silver component 2 in Embodiment 1 of the present invention. Detailed Implementation
[0024] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of 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 skilled in the art without creative effort should fall within the scope of protection of the present invention.
[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0026] Reference Figure 1 As shown, Figure 1 This describes the heat treatment process for photopolymer 3D printed silver components in existing technologies. Specifically, the heat treatment process can be divided into three stages: First, the degreasing stage, where the organic matter inside the silver component is gradually removed, while the intermediate metal particles remain unchanged. After this stage, the organic matter is basically removed, with only a small amount of polymer components remaining inside the molded part to maintain the shape of the blank. The metal powders are not bonded together, but rather in point contact, resulting in a loose overall structure. Figure 1 As shown in (a); in the second stage, as the temperature increases, the atomic activity of the metal powder surface increases, and the diffusion of metal particles gradually changes from point contact to surface contact. The organic components are further reduced, providing support for further sintering, such as... Figure 1 As shown in (b); in the third stage, the temperature further increases, and sintering enters the final stage. The contact surface between particles gradually increases, mainly due to the large amount of atomic movement inside the metal particles, which reduces the distance between particles through diffusion, eventually forming a sintering neck, as shown in (b). Figure 1 As shown in (c), with increasing temperature, a large number of atoms exchange with each other, the sintering neck grows continuously, forming grain boundaries. The grain boundaries sweep through voids and defects, causing volume shrinkage and achieving densification of the sample, as shown in (c). Figure 1 As shown in (d).
[0027] However, during the sintering process described above, a large number of pores will appear inside the silver component. After sintering, the pores will be sealed inside, resulting in low density of the silver component, which in turn leads to low plasticity and toughness.
[0028] Reference Figure 2 As shown, Figure 2This is a flowchart illustrating a method for fabricating a photopolymer-cured 3D printed silver component according to an embodiment of the present invention. The method mainly includes the following steps:
[0029] Step 201: Prepare a silver component preform by using photopolymerization 3D printing technology to prepare a silver component preform from silver photosensitive material. Degrease the silver component preform to obtain a degreased silver component sample.
[0030] In this step, silver-containing photosensitive material is first printed into a silver component preform using photopolymerization 3D printing technology. Then, the silver component preform undergoes a degreasing treatment during heat treatment to remove organic matter from its interior. After this stage, the organic matter is basically removed, meaning that the thermogravimetric analysis of the organic matter components is greater than 80% to 95%, while the intermediate metal particles remain unchanged, resulting in a degreased silver component sample.
[0031] Preferably, the silver powder content in the silver-containing photosensitive material in this step is 70-90% by mass. This mass percentage content meets the requirements for preparing the final silver component.
[0032] It should be noted that, in practical applications, the silver-containing photosensitive materials used in this step mainly include photosensitive resin, silver powder, dispersant, and other organic solvents.
[0033] Step 202: Immerse the degreased silver component sample in a saturated silver salt solution under vacuum. After maintaining the vacuum state for a certain period of time, remove the sample, clean and dry it, and then heat it to obtain the initial silver component sample.
[0034] In this step, after the silver component green body is degreased and before sintering, a saturated silver salt solution is used to fill the voids in the degreased sample of the silver component that has not yet formed a sintering neck. Then, high temperature is used to decompose silver nitrate into silver or silver oxide, thereby increasing the contact area of the particles inside the silver component, reducing porosity, and thus improving its density.
[0035] Preferably, the step of obtaining the initial sample of the silver component specifically includes the following steps:
[0036] 2021. Place the degreased silver component sample in a vacuum chamber, evacuate the chamber, and then inject a saturated silver salt solution at room temperature until it completely covers the degreased silver component sample.
[0037] 2022. Stop injecting saturated silver salt solution, evacuate again and maintain for at least 1 minute, then remove, clean and dry, then heat to the preset temperature and maintain for the preset time to obtain the initial sample of silver component.
[0038] In the above steps, after the degreased silver component sample is cooled in the furnace, it is taken out and placed in a vacuum chamber and evacuated at least twice. Under vacuum, the voids in the degreased silver component sample that has not yet formed a sintering neck are filled with a saturated silver salt solution. The high temperature is used to decompose the silver salt in the pores into silver or silver oxide to fill the pores, thereby increasing the contact area of the particles inside the component, reducing the porosity, reducing the driving force for dense sintering, and significantly improving the sintering density of the component after subsequent sintering.
[0039] Preferably, the vacuum level after both evacuations is 10. -5 ~10 -6 Pa. Since the degreased silver component sample has a porous structure, under this vacuum level, the air in its internal pores can be effectively expelled, which is beneficial for the immersion of saturated silver salt solution.
[0040] Meanwhile, the saturated silver salt solution should be kept at room temperature, as it is prone to crystallization, which hinders its penetration into the degreased sample. The organic solvent used for cleaning can be a quick-drying solvent such as anhydrous ethanol or propanol; this technical solution does not impose any restrictions on this.
[0041] In addition, after vacuuming again, the silver component degreased sample should be kept for at least 1 minute before being taken out. This time period ensures that the saturated silver salt solution can fully penetrate into the pores of the silver component degreased sample.
[0042] Finally, after cleaning and drying, heat to a preset temperature and maintain for a preset time, then remove and cool to room temperature to obtain the initial sample of the silver component.
[0043] Preferably, the preset temperature for heat treatment is 400–500°C, and the preset time is 10–30 min. At this temperature and time, the decomposition temperature and time of the silver salt are fully reached, but the sintering temperature of metallic silver has not yet been reached, thus allowing the silver salt to fully decompose and fill the pores.
[0044] It should be noted that the purpose of this technical solution is to utilize the crystallization and precipitation of a saturated silver salt solution within the pores of the component to fill the pores, thereby increasing the sintering density of the final product. Since the volume of the crystalline silver salt shrinks upon thermal decomposition, multiple operations are required to improve the density. In practical applications, those skilled in the art need to repeat this step 2 to 4 times, depending on the silver content of the photosensitive material, to achieve the desired effect.
[0045] Step 203: Sinter the initial sample of the silver component to obtain the silver component.
[0046] In this step, the initial sample of the silver component obtained in the above steps is sintered to finally obtain a silver component with high density.
[0047] After being treated with this technical solution, the degreased component has its pores filled with saturated silver salt. During the subsequent heat treatment, the silver salt decomposes into silver oxide. The silver oxide spontaneously decomposes into metallic silver during the high-temperature treatment process, which reduces the pores and enhances the metal diffusion and migration effect, thereby further sealing the micropores of the component and ultimately improving the sintering density of the component.
[0048] The silver components treated using this technical solution have a final sintering density that is more than 4% higher than that of untreated components, effectively improving the strength of photopolymer 3D printed silver components.
[0049] The following specific embodiments will further illustrate in detail the method for preparing photopolymer 3D printed silver components provided by the present invention.
[0050] Example 1
[0051] (1) Two 1×1×5cm photosensitive materials with a silver content of 70%wt were printed using photopolymerization 3D printing technology. 3 The silver component blanks are labeled as silver component blank 1 and silver component blank 2, respectively;
[0052] (2) Based on the results of thermogravimetric analysis, the silver component blanks 1 and 2 were heated from room temperature to 420°C at a rate of 0.5°C per minute, with a degreasing rate of 90% as the target, and kept at that temperature for 3 hours to obtain silver component degreasing sample 1 and silver component degreasing sample 2.
[0053] (3) After the silver component degreasing sample 1 was cooled in the furnace, it was taken out, placed in a vacuum chamber, and evacuated twice, with the vacuum degree controlled at 10. -6 Pa. First vacuuming: All air was expelled from the vacuum chamber, then the valve containing a saturated silver nitrate solution at 25°C was opened, and the saturated silver nitrate solution was poured into the container until it completely covered the degreased sample 1 of the silver component; Second vacuuming: The valve of the saturated silver nitrate solution was closed, and vacuuming was performed again and maintained for 1 minute. After removal, the sample was washed with anhydrous ethanol and dried, then placed in a resistance furnace and heated to 460°C for 10 minutes to completely decompose the silver nitrate. After cooling to room temperature, this step was repeated twice to obtain the initial sample 1 of the silver component;
[0054] (4) After heating the initial sample 1 of silver component to 460°C for the last time in step (3), the temperature was directly increased to 920°C at a rate of 1°C per minute. After holding at the temperature for 2 hours, the sample was cooled and removed from the furnace to obtain silver component 1. Its density was then tested.
[0055] (5) After completing step (2), the silver component degreased sample 2 is heated directly from 420°C to 920°C at a rate of 1°C per minute. After holding at the temperature for 2 hours, it is cooled with the furnace and taken out to obtain silver component 2. Its density is then tested.
[0056] Testing revealed that the density of silver component 1 is 97.2% of the theoretical density of pure silver. A scanning electron microscope (SEM) schematic diagram is shown below. Figure 3 As shown; while the density of silver component 2, used as a control, is 90.5%, and its scanning electron microscope schematic diagram is shown in the figure. Figure 4 As shown.
[0057] Example 2
[0058] (1) Two 1×1×5cm photosensitive materials with a silver content of 75%wt were printed using photopolymerization 3D printing technology. 3 The silver component blanks are labeled as silver component blank 3 and silver component blank 4, respectively;
[0059] (2) Based on the results of thermogravimetric analysis, the silver component blanks 3 and 4 were heated from room temperature to 420°C at a rate of 0.5°C per minute, with a degreasing rate of 90% as the target, and kept at that temperature for 3 hours to obtain silver component degreasing sample 3 and silver component degreasing sample 4.
[0060] (3) After the silver component degreasing sample 3 was cooled in the furnace, it was taken out, placed in a vacuum chamber, and evacuated twice, with the vacuum degree controlled at 10. -6 Pa. First vacuuming: All air was expelled from the vacuum chamber, then the valve containing a saturated silver nitrate solution at 25°C was opened, and the saturated silver nitrate solution was poured into the container until it completely covered the degreased silver component sample 3; Second vacuuming: The valve of the saturated silver nitrate solution was closed, and vacuuming was performed again and maintained for 1 minute. After removal, the sample was washed with anhydrous ethanol and dried, then placed in a resistance furnace and heated to 460°C for 10 minutes to completely decompose the silver nitrate. After cooling to room temperature, this step was repeated twice to obtain the initial silver component sample 3;
[0061] (4) After heating the initial sample 3 of the silver component to 460°C for the last time in step (3), the temperature was directly increased to 920°C at a rate of 1°C per minute. After holding at the temperature for 2 hours, the sample was cooled and removed from the furnace to obtain the silver component 3. Its density was then tested.
[0062] (5) After completing step (2), the silver component degreased sample 4 is heated directly from 420°C to 920°C at a rate of 1°C per minute. After holding at the temperature for 2 hours, it is cooled with the furnace and taken out to obtain silver component 4. Its density is then tested.
[0063] Tests showed that the density of silver component 3 was 98.6% of the theoretical density of pure silver, while the density of silver component 4, used as a control, was 92.2%.
[0064] Example 3
[0065] (1) Two 1×1×5cm photosensitive materials with a silver content of 82%wt were printed using photopolymerization 3D printing technology. 3 The silver component blanks are labeled as silver component blank 5 and silver component blank 6, respectively;
[0066] (2) Based on the results of thermogravimetric analysis, the silver component blanks 5 and 6 were heated from room temperature to 420°C at a rate of 0.5°C per minute, with a degreasing rate of 90% as the target, and kept at that temperature for 3 hours to obtain silver component degreasing sample 5 and silver component degreasing sample 6.
[0067] (3) After the silver component degreasing sample 5 was cooled in the furnace, it was taken out, placed in a vacuum chamber, and vacuumed twice, with the vacuum degree controlled at 10. -6 Pa. First vacuuming: All air was expelled from the vacuum chamber, then the valve containing a saturated silver nitrate solution at 25°C was opened, and the saturated silver nitrate solution was poured into the container until it completely covered the degreased silver component sample 5; Second vacuuming: The valve of the saturated silver nitrate solution was closed, and vacuuming was performed again and maintained for 1 minute. After removal, the sample was washed with anhydrous ethanol and dried, then placed in a resistance furnace and heated to 460°C for 10 minutes to completely decompose the silver nitrate. After cooling to room temperature, this step was repeated twice to obtain the initial silver component sample 5;
[0068] (4) After heating the initial sample 5 of the silver component to 460°C for the last time in step (3), the temperature was directly increased to 920°C at a rate of 1°C per minute. After holding at the temperature for 2 hours, the sample was cooled and removed from the furnace to obtain the silver component 5. Its density was then tested.
[0069] (5) After completing step (2), the silver component degreased sample 6 was heated directly from 420°C to 920°C at a rate of 1°C per minute. After holding at the temperature for 2 hours, it was cooled with the furnace and taken out to obtain the silver component 6. Its density was then tested.
[0070] Tests showed that the density of silver component 5 was 99.1% of the theoretical density of pure silver, while the density of silver component 4, used as a control, was 94.5%.
[0071] As can be seen from the above three embodiments, the pores of the degreased component treated with this technical solution are filled with saturated silver salt. In the subsequent heat treatment, the silver salt decomposes into silver oxide. During the high-temperature treatment, the silver oxide spontaneously decomposes into metallic silver, which plays a role in reducing pores and improving the metal diffusion and migration effect, thereby further sealing the micropores of the component and ultimately improving the sintering density of the component.
[0072] The silver components treated using this technical solution have a final sintering density that is more than 4% higher than that of untreated components, effectively improving the strength of photopolymer 3D printed silver components.
[0073] In summary, the method for preparing photopolymerizable 3D printed silver components provided in this embodiment of the invention involves degreasing the silver component preform, filling the internal voids of the silver component before the sintering neck has formed using a saturated silver salt solution under vacuum, and then using high temperature to decompose the silver salt into silver or silver oxide. This increases the contact area of the internal particles of the silver component, reduces the porosity, lowers the driving force for dense sintering, significantly improves the sintering density of the final sintered silver component, and effectively improves the plasticity and toughness of the silver component.
[0074] This method is simple to prepare, has a short processing cycle, is inexpensive, and does not require high initial sample density, thus effectively meeting practical needs.
[0075] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.
[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing photopolymerizable 3D printed silver components, characterized in that, include: Silver component preforms were prepared from silver-containing photosensitive materials using photopolymerization 3D printing technology. The silver component preforms were then degreased to obtain degreased silver component samples. The degreased sample of the silver component was immersed in a saturated silver salt solution under vacuum. After maintaining the vacuum state for a certain period of time, it was taken out, cleaned and dried, and then subjected to heat treatment to obtain the initial sample of the silver component. The initial sample of the silver component was sintered to obtain the silver component.
2. The preparation method according to claim 1, characterized in that, The silver powder content in the silver-containing photosensitive material is 70-90% by mass.
3. The preparation method according to claim 1, characterized in that, The step of obtaining the initial sample of the silver component includes: The degreased sample of the silver component was placed in a vacuum chamber, and after evacuation, a saturated silver salt solution at room temperature was injected until it completely covered the degreased sample of the silver component. Stop injecting the saturated silver salt solution, evacuate again and hold for at least 1 minute, then remove, clean and dry, then heat to a preset temperature and hold for a preset time to obtain the initial sample of the silver component.
4. The preparation method according to claim 3, characterized in that, The vacuum level was 10 after both vacuuming operations. -5 ~10 - 6 Pa.
5. The preparation method according to claim 3, characterized in that, The preset temperature is 400-500℃, and the preset time is 10-30 minutes.