A high-transparency glass powder for 3D printing and its preparation method

Abstract

The present invention relates to a high-transparency glass powder for 3D printing, which is characterized by being made of raw materials in the following weight percentages: SiO 2 70 - 78 wt%, Al 2 O 3 8 - 15 wt%, GeO 2 0.5 - 2 wt%, BeO 0.2 - 1 wt%, K 2 O 6 - 10 wt%, BaO 1.5 - 3.5 wt%, ZnO 2 - 7 wt%, CaF 2 0.5 - 1 wt%, (NH 4 ) 2 SO 4 0.2 - 1 wt%, NaSO 4 1 - 2 wt%; wherein 6.0 wt% ≤ K 2 O + BeO ≤ 10.0 wt%, 3.0 wt% ≤ BaO + ZnO ≤ 8.0 wt%, 1.0 wt% ≤ (NH 4 ) 2 SO 4 +Na 2 SO 4 +CaF 2 ≤ 4.0 wt%. Advantages of the present invention: The glass powder of the present invention has a high transmittance after 3D printing and sintering, and a good particle size grading effect. After high-temperature vacuum sintering of the degreased 3D printing finished product, the bubbles on the surface and inside of the glass are greatly reduced. Without deformation of the sintered glass, the density of the finished product is relatively high, reaching more than 99%; the transmittance is greater than 82%, greatly improving the transparency of the glass.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of glass powder, and relates to a highly transparent glass powder for 3D printing and a preparation method thereof. Background Art

[0002] 3D printing is a technology that constructs three-dimensional objects by means of layer-by-layer printing (or curing, bonding, sintering, etc.) based on digital model files and using computer-aided design and control. 3D printing technology has the advantages of saving materials, high production efficiency, flexible printed objects, high printing accuracy, low production cost, and being able to achieve structures and functions that cannot be achieved by traditional subtractive manufacturing technologies, and is considered an important development direction for future industrial manufacturing. Glass is widely used due to its excellent optical properties, mechanical properties, electrical / thermal insulation properties, and chemical stability. Glass 3D printing technology can not only produce glass components with complex shapes and structures, but also manufacture high-precision products that are difficult to achieve by traditional glass processing technologies. However, currently, 3D printing of glass faces many challenges, such as limited selection of printing materials, long printing process, limited precision, and high cost. Glass 3D printing technology is still in the research stage and has not achieved large-scale commercial application.

[0003] In addition to the properties of glass itself, especially its high thermal stability, it is very difficult to manufacture glass products using 3D printing technology. The common difficulty also lies in that, compared with metals or ceramics, the printed glass products have very high requirements for transparency. In order to achieve a high transmittance, it is necessary to sinter to full density. Otherwise, the presence of pores and inhomogeneity inside will cause light scattering, resulting in the glass being opaque; and during the sintering process, it is necessary to ensure that the glass does not melt and deform.

[0004] Klein et al. used the fused deposition modeling method to perform 3D printing of soda-lime glass. The nozzle continuously extruded the molten glass at a constant speed. By controlling the movement of the nozzle, glass objects of different shapes could be printed. The glass devices printed by this method had a relatively smooth surface and high optical transmittance. However, there are still many challenges in the 3D printing of complex glass structures using this technology. First of all, a temperature control system must be used to precisely control the temperature of the nozzle. Otherwise, it is difficult for the molten glass to be smoothly extruded from the nozzle, resulting in printing failure. In addition, the Z-axis interlayer adhesion of the glass devices printed by this technology is poor, and there is an obvious "staircase effect" at the edges of each layer printed, resulting in a decrease in accuracy and affecting product quality. In addition, the stereolithography technology can be used to manufacture glass devices with small size, high precision, excellent light transmission performance and mechanical properties. Therefore, the stereolithography technology is also considered to be a technology most promising for realizing 3D precision printing of glass. In 2017, Kotz et al. used the stereolithography technology to perform 3D printing of silica glass and manufactured pore-free, crack-free and transparent glass samples. However, for other conventional glasses, there are very few reports on preparing transparent glasses using the stereolithography 3D printing method.

[0005] After 3D printing and forming, the finished product first needs to be degreased and sintered at low temperature, and then needs to be sintered at high temperature for the second time to achieve various properties of the glass. During the sintering process, it is necessary to ensure that the printed shape does not change and at the same time sinter a transparent glass, which is very difficult. Ordinary glass turns white after sintering and has a very low transmittance. Summary of the Invention

[0006] The object of the present invention is to solve the problem that the glass turns white and has a low transparency after 3D printing of existing glass powder, and to provide a high-transparency glass powder for 3D printing and its preparation method. On the one hand, the present invention adjusts the glass formula and uses a large amount of raw materials that can improve the transparency of the glass in the formula. On the other hand, through appropriate particle size grading of the glass powder, and finally sintering the glass in a vacuum environment (removing the bubbles in the sample to achieve a high density, reducing the reflection of the sample to light), so that the glass after 3D printing and forming and sintering has high transparency (transmittance greater than 82%).

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A high-transparency glass powder for 3D printing, characterized in that it is made of the following raw materials by weight percentage: SiO 2 70~78 wt%, Al 2 O 3 8~15 wt%, GeO 2 0.5~2 wt%, BeO 0.2~1 wt%, K2 O 6 to 10 wt%, BaO 1.5 to 3.5 wt%, ZnO 2 to 7 wt%, CaF 2 0.5 to 1 wt%, (NH 4 ) 2 SO 4 0.2 to 1 wt%, NaSO 4 1 to 2 wt%; wherein 6.0 wt% ≤ K 2 O + BeO ≤ 10.0 wt%, 3.0 wt% ≤ BaO + ZnO ≤ 8.0 wt%, 1.0 wt% ≤ (NH 4 ) 2 SO 4 + Na 2 SO 4 + CaF 2 ≤ 4.0 wt%.

[0009] Furthermore, a highly transparent glass powder for 3D printing, characterized in that it is made of raw materials in the following weight percentages: SiO 2 72 to 78 wt%, Al 2 O 3 8 to 13 wt%, GeO 2 0.5 to 1.5 wt%, BeO 0.2 to 0.8 wt%, K 2 O 6 to 9 wt%, BaO 1.5 to 3.0 wt%, ZnO 2 to 6 wt%, CaF 2 0.6 to 1 wt%, (NH 4 ) 2 SO 4 0.2 to 0.8 wt%, NaSO 4 1 to 1.8 wt%; wherein 6.0 wt% ≤ K 2 O + BeO ≤ 9.8 wt%, 3.2 wt% ≤ BaO + ZnO ≤ 8.0 wt%, 1.2 wt% ≤ (NH 4 ) 2 SO 4 + Na 2 SO 4 + CaF 2 ≤ 3.8 wt%.

[0010] Furthermore, a highly transparent glass powder for 3D printing, characterized in that it is made of raw materials in the following weight percentages: SiO 2 73 to 78 wt%, Al 2 O 38 to 12 wt%, GeO 2 0.5 to 1.5 wt%, BeO 0.2 to 0.8 wt%, K 2 O 6 to 9 wt%, BaO 1.5 to 3 wt%, ZnO 2 to 5 wt%, CaF 2 0.6 to 1 wt%, (NH 4 ) 2 SO 4 0.2 to 0.8 wt%, NaSO 4 1 to 1.8 wt%; where 6.0 wt% ≤ K 2 O + BeO ≤ 9.5 wt%, 3.5 wt% ≤ BaO + ZnO ≤ 8.0 wt%, 1.5 wt% ≤ (NH 4 ) 2 SO 4 + Na 2 SO 4 + CaF 2 ≤ 3.5 wt%.

[0011] Furthermore, a high-transparency glass powder for 3D printing, characterized in that: the glass powder with particle sizes greater than 30 μm, 20 - 30 μm, 10 - 20 μm, and less than 10 μm respectively account for 5 - 9%, 8 - 13%, 65 - 72%, and 10 - 15% of the total weight of the glass powder.

[0012] Furthermore, a high-transparency glass powder for 3D printing, characterized in that: the glass powder with particle sizes greater than 30 μm, 20 - 30 μm, 10 - 20 μm, and less than 10 μm respectively account for 5 - 8%, 8 - 12%, 67 - 72%, and 10 - 14% of the total weight of the glass powder.

[0013] A preparation method of a high-transparency glass powder for 3D printing, characterized by including the following steps:

[0014] (1) Prepare raw materials according to the above weight percentages. Use carbonate raw materials for oxides. Mix all raw materials evenly, put them into a platinum crucible for melting. The melting temperature is 1540°C - 1560°C, keep warm for 2 h. Take out the melted and clarified glass liquid from the high-temperature furnace, pour it into a mold for shaping. Transfer the cast glass to an annealing furnace, anneal at 500°C - 550°C for 2 h, and then cool it to room temperature with the furnace.

[0015] (2) The annealed glass is placed in a roller crusher for crushing to obtain glass particles with a particle size of about 1 mm. Then, through an ultrafine grinding system, a high-energy ball milling system, and a precision screening system, glass powders with different particle sizes are classified, such that the particle size distribution of the glass powder is as follows: glass powders with a particle size greater than 30 μm, 20 - 30 μm, 10 - 20 μm, and less than 10 μm account for 5 - 8%, 8 - 12%, 67 - 72%, and 10 - 14% of the total weight of the glass powder, respectively. Thus, a high-transparency glass powder for 3D printing is obtained.

[0016] Further, the high-transparency glass powder for 3D printing, a photoinitiator, and a photosensitive resin are mixed in a weight ratio of 80 - 92%: 0.18 - 0.6%: 6 - 21% to form a slurry; it is printed layer by layer by irradiating with a DLP light source, and after printing is completed, it is degreased at 460 - 530 °C; after degreasing is completed, it is subjected to vacuum sintering, and then cooled to room temperature and polished to obtain high-transparency 3D printed glass.

[0017] Further, the temperature of the vacuum sintering is 1250 - 1290 °C, and it is kept warm for 45 - 60 min.

[0018] Further, the density of the high-transparency 3D printed glass reaches more than 99%, and the transmittance is greater than 82%.

[0019] In the present invention, BeO and K 2 O are used in the glass formula to improve the transmittance of the glass. BeO can participate in the network structure in the form of beryllium oxygen tetrahedrons, can significantly reduce the thermal expansion coefficient of the glass, improve the thermal stability and chemical stability, and increase the transmittance. K 2 O, as the only alkali metal oxide in the glass powder and also a network external oxide, can reduce the crystallization tendency of the glass, increase the transparency and gloss of the glass; however, BeO is toxic, and an excessive addition amount of K 2 O will cause a decline in the mechanical properties and chemical stability of the glass. Therefore, a certain amount of Al 2 O 3 , BaO, and ZnO are added to solve this problem; in addition, adding a certain amount of BaO and ZnO can make the structure of the glass more stable, improve the density and gloss of the glass, reduce the reflection of light by the glass, and thus improve the transmittance of the glass; however, an excessive addition amount of BaO and ZnO will generate bubbles and cause crystallization problems. (NH 4 ) 2 SO 4 , Na 2 SO 4CaF provides alkali metal ions and alkaline earth metal ions for the glass and acts as a fining agent for the glass. Among them, the sulfate has a high decomposition temperature and significant fining effect at high temperatures. When the three are used together, the fining effect is better, greatly reducing the light reflection caused by internal pores and inhomogeneity, thereby improving the transmittance of the glass. However, since sulfates and fluorides are not environmentally friendly, they should not be used in excess. Therefore, it is preferred that 6.0 wt% ≤ K 2 O + BeO ≤ 9.5 wt%, 3.5 wt% ≤ BaO + ZnO ≤ 8.0 wt%, 1.5 wt% ≤ (NH 4 ) 2 SO 4 + Na 2 SO 4 + CaF 2 ≤ 3.5 wt%.

[0020] The size of the powder particle diameter has a direct impact on the fluidity and bulk density of the 3D printing material, and also affects the mechanical properties of the printed parts. Smaller powder particle diameters can provide higher printing resolution, making the printed parts more delicate. However, overly small powder particle diameters will also increase the surface area of the printing material, causing the powder to be more prone to moisture absorption during the printing process, thereby affecting the printing quality. Larger powder particle diameters will affect the fluidity of the powder, resulting in defects such as uneven packing and pores, reducing the density of the printed parts. Therefore, when preparing 3D printing glass powder, it is necessary to balance between the powder particle diameter and the material properties to ensure the quality and performance of the printed parts, usually between a few microns and dozens of microns. By selecting powder with different particle diameters for mixing, the small particle diameters can fill the gaps between the large particle diameters, making the density of the 3D printed sample higher. Therefore, the particle size distribution of the glass powder used in the present invention is as follows: glass powder with a particle diameter greater than 30μm, 20 - 30μm, 10 - 20μm, and less than 10μm respectively accounts for 5 - 8%, 8 - 12%, 67 - 72%, and 10 - 14% of the total weight of the glass powder.

[0021] Advantages of the present invention: Different from ordinary glass powder for 3D printing, the glass powder of the present invention has a high transmittance after 3D printing and sintering, and a good particle size grading effect. After high-temperature vacuum sintering of the 3D printed finished product after degreasing, the bubbles on the surface and inside of the glass are greatly reduced. Without deformation, the density of the sintered glass is relatively high, reaching more than 99%; the transmittance is greater than 82%, greatly improving the transparency of the glass. Specific Embodiments

[0022] A preparation method of high-transparency glass powder for 3D printing, the specific implementation steps are as follows: Examples

[0023] (1)Weigh according to the ratio in Table 1: Mix all raw materials evenly, put them into a platinum crucible for melting. The melting temperature is 1550 °C, keep warm for 2 h. Take out the melted and clarified glass liquid from the high-temperature furnace, pour it into a mold for forming. Transfer the cast glass to an annealing furnace, anneal at 500 °C for 2 h, and then cool to room temperature with the furnace;

[0024] (2)Put the cooled glass in a roller crusher for crushing to obtain glass particles with a particle size of about 1 mm. Then, through an ultrafine grinding system, a high-energy ball milling system, and a precision screening system, classify glass powders with different particle sizes, so that the particle size distribution of the glass powder is as follows: The glass powders with particle sizes greater than 30 μm, 20 - 30 μm, 10 - 20 μm, and less than 10 μm account for 7%, 10%, 68%, and 13% of the total weight of the glass powder respectively, obtaining a high-transparency glass powder for 3D printing;

[0025] (3)Mix 89 g of high-transparency glass powder, 0.5 g of trimethylbenzoyl-diphenylphosphine oxide (TPO), 10.5 g of HDDA (1,6 - hexanediamine), a mixture of TMPTA (trimethylolpropane trimethacrylate) and EA (ethyl acrylate) (where HDDA is 6.3 g, TMPTA is 2.6 g, and EA is 1.6 g) into a slurry, and perform layer-by-layer printing by irradiating with a light source through the DLP method. After printing, carry out debinding at 500 °C, raise the temperature to 500 °C at a heating rate of 0.5 °C / min, keep warm for 120 min, and then cool to room temperature with the furnace;

[0026] (4)Subsequently, place it in a vacuum furnace. First, evacuate for 30 min, and then raise the temperature at a rate of 2 °C / min. To ensure that the glass does not deform after sintering and to ensure a high transmittance, the sintering temperatures are set at 1220 °C, 1240 °C, 1260 °C, and 1280 °C respectively, keep warm for 2 h, and after cooling to room temperature with the furnace, grind and polish to obtain a high-transparency 3D printing glass, and test the density and transmittance of the sample (see Samples 1 - 5 in Table 1).

[0027] Comparative Example 1

[0028] Prepare using the same particle size distribution and vacuum sintering method as in Example 1. The difference from Example 1 is that ordinary soda-lime-silica glass is used in this example, with 72 wt% SiO 2 、14.5 wt% Na 2 O、0.5 wt% K 2 O、2.5 wt% MgO、9 wt% CaO and 1.5 wt% Al 2 O 3 . The density and transmittance of the obtained 3D printing glass are shown in Comparative Example 1 of Table 1. The density is slightly lower, but the transmittance is greatly reduced.

[0029] Comparative Example 2

[0030] It was prepared by the same method as in Example 1. The difference from Example 1 is that in this example, the proportion of glass powder with a particle size of 20 - 30 μm in the glass powder obtained by classification in step (2) is more than 95%, and the particle size is relatively single. The density and transmittance of the finally obtained 3D printed glass are both reduced, as shown in Comparative Example 2 of Table 1.

[0031] Comparative Example 3

[0032] It was prepared by the same method as in the example. The difference from Example 1 is that in this example, the sintering process in step (4) uses an ordinary high-temperature furnace under atmospheric pressure conditions. The density and transmittance of the finally obtained 3D printed glass are both greatly reduced, as shown in Comparative Example 3 of Table 1.

[0033]

Claims

1. A high-transparency glass powder for 3D printing, characterized in that Made from raw materials with the following weight percentages: SiO 2 70 - 78 wt%, Al 2 O 3 8 - 15 wt%, GeO 2 0.5 - 2 wt%, BeO 0.2 - 1 wt%, K 2 O 6 - 10 wt%, BaO 1.5 - 3.5 wt%, ZnO 2 - 7 wt%, CaF 2 0.5 - 1 wt%, (NH 4 ) 2 SO 4 0.2 - 1 wt%, NaSO 4 1 - 2 wt%; wherein 6.0 wt% ≤ K 2 O + BeO ≤ 10.0 wt%, 3.0 wt% ≤ BaO + ZnO ≤ 8.0 wt%, 1.0 wt% ≤ (NH 4 ) 2 SO 4 + Na 2 SO 4 + CaF 2 ≤ 4.0 wt%; in the glass powder, the glass powder with a particle size greater than 30 μm, 20 - 30 μm, 10 - 20 μm, and less than 10 μm respectively accounts for 5 - 8%, 8 - 12%, 67 - 72%, and 10 - 14% of the total weight of the glass powder.

2. The high-transparency glass powder for 3D printing according to claim 1, characterized in that: Made from raw materials with the following weight percentages: SiO 2 72 - 78 wt%, Al 2 O 3 8 - 13 wt%, GeO 2 0.5 - 1.5 wt%, BeO 0.2 - 0.8 wt%, K 2 O 6 - 9 wt%, BaO 1.5 - 3.0 wt%, ZnO 2 - 6 wt%, CaF 2 0.6 - 1 wt%, (NH 4 ) 2 SO 4 0.2 - 0.8 wt%, NaSO 4 1 - 1.8 wt%; where 6.0 wt% ≤ K 2 O + BeO ≤ 9.8 wt%, 3.2 wt% ≤ BaO + ZnO ≤ 8.0 wt%, 1.2 wt% ≤ (NH 4 ) 2 SO 4 + Na 2 SO 4 + CaF 2 ≤ 3.8 wt%.

3. The high-transparency glass powder for 3D printing according to claim 1, characterized in that: Made from the following raw materials by weight percentage: SiO 2 73 - 78 wt%, Al 2 O 3 8 - 12 wt%, GeO 2 0.5 - 1.5 wt%, BeO 0.2 - 0.8 wt%, K 2 O 6 - 9 wt%, BaO 1.5 - 3 wt%, ZnO 2 - 5 wt%, CaF 2 0.6 - 1 wt%, (NH 4 ) 2 SO 4 0.2 - 0.8wt%, NaSO 4 1 - 1.8wt%; where 6.0wt% ≤ K 2 O + BeO ≤ 9.5 wt%, 3.5 wt% ≤ BaO + ZnO ≤ 8.0 wt%, 1.5wt% ≤ (NH 4 ) 2 SO 4 + Na 2 SO 4 + CaF 2 ≤ 3.5 wt%.

4. A preparation method of the high-transparency glass powder for 3D printing according to claim 1, characterized in that it includes the following steps: (1) Prepare raw materials according to the above weight percentages. Use the carbonate raw materials of the oxides. Mix all the raw materials evenly, put them into a platinum crucible for melting. The melting temperature is 1540°C - 1560°C, keep warm for 2h. Take out the melted and clarified glass liquid from the high-temperature furnace, pour it into a mold for forming. Transfer the cast glass to an annealing furnace, anneal it at 500°C - 550°C for 2h, and then cool it to room temperature with the furnace; (2) Place the annealed glass in a roller crusher for crushing to obtain glass particles with a particle size of about 1mm. Then, through an ultrafine pulverization system, a high-energy ball milling system, and a precision screening system, classify glass powders with different particle sizes, so that the particle size distribution of the glass powder is as follows: glass powders with a particle size greater than 30μm, 20 - 30μm, 10 - 20μm, and less than 10μm respectively account for 5 - 8%, 8 - 12%, 67 - 72%, and 10 - 14% of the total weight of the glass powder, thus obtaining a high-transparency glass powder for 3D printing.

5. The high-transparency glass powder for 3D printing according to claim 1, characterized in that: Mix the high-transparency glass powder for 3D printing, a photoinitiator, and a photosensitive resin in a weight ratio of 80 - 92%: 0.18 - 0.6%: 6 - 21% to form a slurry; irradiate and print layer by layer through a DLP light source. After printing, carry out debinding at 460°C - 530°C; after debinding, carry out vacuum sintering, and then cool to room temperature and polish to obtain high-transparency 3D printing glass.

6. The high-transparency glass powder for 3D printing according to claim 5, characterized in that: The temperature of the vacuum sintering is 1250°C - 1290°C, and keep warm for 45 - 60 min.

7. The high-transparency glass powder for 3D printing according to claim 5, characterized in that: The density of the high-transparency 3D printing glass reaches more than 99%, and the transmittance is greater than 82%.

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