Additive manufacturing borosilicate glass and method of making the same

Abstract

The application relates to a preparation method of an additive manufacturing borosilicate glass, characterized in that: (1) main glass powder and low-melting-point glass powder are uniformly mixed to obtain a mixture at a mass ratio of 95-98:2-5, the mixture, a photoinitiator and a photosensitive resin are mixed at a mass ratio of 82-92:0.15-0.5:5-19 to prepare a slurry; (2) a 3D printing is carried out by using a photocuring method, and after the printing is completed, degreasing is carried out, and after the degreasing is completed, vacuum sintering is carried out to obtain transparent 3D printing glass; (3) the 3D printing glass is subjected to twice ion exchange reaction, and after the twice ion exchange reaction is completed, cleaning is carried out. The application has the advantages that: twice chemical toughening is carried out on the sintered finished product glass, the mechanical properties of the glass are improved, the 3D printing formed sintered glass has high chemical stability, thermal stability and good mechanical properties, the maximum surface stress is 872 MPa, the maximum Vickers hardness is 690 MPa, and the bending strength reaches 159 MPa.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of additive manufacturing of glass, and relates to an additive manufacturing borosilicate glass and a preparation method thereof. BACKGROUND

[0002] Traditional glass manufacturing methods are difficult to produce high-precision glass devices with complex shapes and structures, while additive manufacturing methods can solve the above problems. Additive manufacturing (also known as 3D printing technology) has the advantages of saving materials, high production efficiency, flexible printed objects, high printing precision, low production cost, and can realize structures and functions that cannot be realized by traditional subtractive manufacturing technology, and is considered an important development direction for future industrial manufacturing.

[0003] Due to the excellent physical and chemical properties of inorganic non-metallic materials, 3D printed glass devices are expected to be applied in many fields such as electronics, chemistry, biology, optics, and medicine. Microfluidics, also known as Lab-on-Chip or microfluidic chip technology, is a device that precisely controls and manipulates microscale fluid flow. This technology can integrate sample preparation, reaction, separation, detection, and other basic operation units of biological, chemical, and medical analysis processes into a micron-scale chip to automatically complete the entire analysis process. Due to its great potential in biology, chemistry, and medicine, microfluidic chips have been widely used in many research fields at the intersection of biology, chemistry, medicine, fluid, electronics, materials, and mechanics.

[0004] The current mainstream microfluidic material is polydimethylsiloxane (PDMS), but PDMS is a thermoelastic polymer material. This type of material is hydrophobic, not resistant to high temperature and high pressure, easily corroded by acidic or alkaline solutions, and easily adheres to surface active substances in the fluid, causing blockage in the pipeline. Glass has good physical and chemical stability, strong resistance to high temperature and high pressure, excellent optical transparency, a smooth surface, and low adhesion, making it an ideal replacement material for PDMS. Due to the difficulty of traditional manufacturing methods in realizing the manufacturing of glass microfluidic devices, the use of 3D printing technology to manufacture microfluidic chips can realize the rapid manufacturing of microfluidic channels in a short time, which is beneficial to the rapid iteration of microfluidic chip design and accelerates the innovation speed based on microfluidic research.

[0005] The 3D printing technology of glass faces many challenges. Since quartz glass has excellent performance in all aspects, some foreign manufacturers use silica glass powder as raw material to prepare glass products with excellent optical performance. However, quartz glass has a high melting point, and the density of the glass product after 3D printing and sintering is poor. By querying relevant literature, researchers found that the performance of 3D printed glass prepared by using sodium calcium silicon glass powder and borate glass powder system is poor, which is difficult to be commercialized. In the process of additive manufacturing, it is necessary to overcome the difficulties in glass melting, forming and cooling. At the same time, the viscosity range of glass is relatively narrow, and the control of processing temperature and speed is relatively high. Compared with metal or plastic materials, the process technology of glass additive manufacturing is relatively immature, and it is difficult to achieve high-precision forming. It is also necessary to develop CAD software and modeling methods suitable for glass to realize accurate design and prediction of deformation and stress distribution in the manufacturing process. In summary, the additive manufacturing of glass has the problems of limited material selection, low forming precision, poor performance, high cost and other problems, which is difficult to meet the standards of commercial use. SUMMARY

[0006] The purpose of the present application is to solve the problems of poor sintering density, low chemical stability, poor mechanical properties and poor optical performance of the glass prepared by the existing 3D printing technology. The present application provides an additive manufacturing borosilicate glass and a preparation method thereof. In one aspect, the above-mentioned purpose is achieved by adjusting the glass formula. The silica raw material is used as the matrix, a small amount of boron oxide and lithium oxide is added in the formula to improve the optical performance of the glass, improve the thermal stability and chemical stability of the glass, and a small amount of low melting point glass powder is added in the glass powder to achieve fluxing and improve the density. In another aspect, the mechanical properties of the glass are improved by carrying out two chemical tempering reactions on the sintered finished glass. Thus, the 3D printed and sintered glass has high chemical stability, thermal stability and good mechanical properties.

[0007] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0008] An additive manufacturing borosilicate glass is characterized by being made of the following raw materials in mass percentage: mixed glass powder 82-92%, photoinitiator 0.15-0.5%, and photosensitive resin 5-19%, wherein the mixed glass powder is composed of 95-98% of main glass powder and 2-5% of low melting point glass powder.

[0009] Further, the mixed glass powder is composed of 96-98% of main glass powder and 2-4% of low melting point glass powder.

[0010] Further, the host glass powder consists of, in mass percentage, SiO2 88-93 wt%, B2O3 5-9 wt%, Li2O 1.2-5 wt%, and Ba(NO3)2 0.5-1.5 wt%, wherein 8.0 wt%≤ B2O3 + Li2O ≤ 13.0 wt%; and the low-melting glass powder consists of, in mass percentage, Bi2O3 65-75 wt%, B2O3 7-13 wt%, ZnO 8-12 wt%, BaO 4-8 wt%, and SiO2 0.5-3 wt%.

[0011] Further, the host glass powder consists of, in mass percentage, SiO2 88-93 wt%, B2O3 5-9 wt%, Li2O 1.2-5 wt%, and Ba(NO3)2 0.5-1.5 wt%, wherein 8.0 wt%≤ B2O3 + Li2O ≤ 13.0 wt%; and the low-melting glass powder consists of, in mass percentage, Bi2O3 65-75 wt%, B2O3 7-13 wt%, ZnO 8-12 wt%, BaO 4-8 wt%, and SiO2 0.5-3 wt%.

[0012] Further, the host glass powder consists of, in mass percentage, SiO2 88-93 wt%, B2O3 5-9 wt%, Li2O 1.2-5 wt%, and Ba(NO3)2 0.5-1.5 wt%, wherein 8.0 wt%≤ B2O3 + Li2O ≤ 13.0 wt%; and the low-melting glass powder consists of, in mass percentage, Bi2O3 65-75 wt%, B2O3 7-13 wt%, ZnO 8-12 wt%, BaO 4-8 wt%, and SiO2 0.5-3 wt%.

[0013] Further, the photoinitiator is trimethylbenzoyl-diphenylphosphine oxide (TPO).

[0014] Further, the photosensitive resin is a mixture of 1,6-hexanediamine (HDDA), trimethylolpropane trimethacrylate (TMPTA), and ethyl acrylate (EA).

[0015] A method of manufacturing a borosilicate glass by additive manufacturing, characterized in that it comprises the following steps:

[0016] (1) The raw materials are weighed according to the following mass percentages: SiO2 88-93 wt%, B2O3 5-9 wt%, Li2O 1.2-5 wt%, and Ba(NO3)2 0.5-1.5 wt%, wherein 8.0 wt%≤B2O3+Li2O≤13.0 wt%, and then mixed uniformly and melted (melting temperature: 1625-1635℃), and then the glass block is ground into micron-sized powder (10-30μm) as the main glass powder;

[0017] (2) The raw materials are weighed according to the following mass percentages: Bi2O3 65-75 wt%, B2O3 7-13 wt%, ZnO 8-12 wt%, BaO 4-8 wt%, and SiO2 0.5-3 wt%, mixed uniformly and melted (melting temperature: 850-900℃), and then the glass block is ground into micron-sized powder (10-30μm) as the low-melting-point glass powder;

[0018] (3) The main glass powder and the low-melting-point glass powder are mixed in a mass ratio of 95-98:2-5 to obtain a mixture, and then the mixture, a photoinitiator, and a photosensitive resin are mixed in a mass ratio of 82-92:0.15-0.5:5-19 to prepare a slurry;

[0019] (4) The slurry is printed by using a photocuring method, and then debinding is performed, wherein the debinding temperature system is as follows: the temperature is raised to 540-580℃ at a rate of 0.5℃ / min and kept for 2-3h; then the temperature is lowered to 40℃ at a rate of 1℃ / min; and then vacuum sintering is performed, wherein the vacuum degree is extracted to 45-55Pa, the temperature is raised to 1240-1270℃ at a rate of 2℃ / min and kept for 2-3h, and then the temperature is lowered to 40℃ at a rate of 2℃ / min, to obtain transparent 3D-printed glass;

[0020] (5) The 3D-printed glass is subjected to secondary ion exchange reaction, wherein the 3D-printed glass preheated to 320℃ is immersed in a sodium nitrate salt solution with a temperature of 400-450℃, and the ion exchange time is 1.5-3h, so that the sodium ions in the molten salt and the lithium ions in the glass are subjected to sufficient ion exchange reaction; after the reaction is completed, the glass is cooled in a muffle furnace at 380℃, the cooling rate is 5℃ / min, and after the glass is cooled to room temperature, it is cleaned and dried by using an ultrasonic instrument; then the second ion exchange reaction is performed, wherein the 3D-printed glass preheated to 300℃ is placed in a potassium nitrate salt solution with a temperature of 360-410℃, and the ion exchange time is about 1.5-3h, so that the potassium ions in the molten salt and the sodium ions and lithium ions on the surface layer of the glass are subjected to sufficient ion exchange reaction, and after the reaction is completed, the glass is cooled in a muffle furnace at 380℃, the cooling rate is 5℃ / min, and then cleaning is performed.

[0021] The application adds B2O3 and Li2O raw materials in SiO2 raw materials, B2O3 forms a structure network with silicon oxygen tetrahedron in borate glass, can reduce the expansion coefficient of the glass, improve the thermal stability and chemical stability of the glass, improve the gloss of the glass, improve the mechanical properties of the glass, in addition, boron oxide can reduce the viscosity of the glass at high temperature, increase the forming temperature range of the glass, accelerate the melting and fining of the glass; Li2O is an external network oxide, has a broken bond effect, is a strong flux, can reduce the expansion coefficient of the glass, and the crystallization tendency is small. However, excessive amount will make the glass crystallization tendency larger, therefore, SiO2 is preferably 89-93 wt%, B2O3 is preferably 6-9 wt%, and Li2O is preferably 2-4 wt%, wherein 8.0 wt%≤B2O3+Li2O≤12.0 wt%. Ba(NO3)2 is used as a glass fining agent, has a high decomposition temperature and good fining effect, and is commonly used in optical glass, but nitrate is not environmentally friendly, and should not be used in excess, therefore, 0.8-1.2 wt% is preferred. In addition, a small amount of low melting point glass powder is added to the glass powder to achieve the purpose of fluxing and improving the density, and the ratio of the main glass powder to the low melting point glass powder is preferably 96-98 wt%:2-4 wt%.

[0022] In view of the poor mechanical properties of the additive manufacturing glass, the glass product printed and sintered is chemically tempered twice, the ions with large radius in the molten salt are exchanged with the alkali metal ions with small radius on the surface of the glass, after the ion exchange, the compressive stress CS is formed on the surface of the glass, the larger the volume difference between the two ions, the greater the compressive stress, the compressive stress can effectively seal the microcracks on the surface of the glass, prevent and delay the expansion of the microcracks to the interior of the glass, which is equivalent to setting a layer of "armor" on the surface of the glass, improving the bending resistance, compression resistance, impact resistance, scratch resistance and other mechanical properties of the glass. Since R(Li + ) < R(Na + ) < R(K + ), the sodium ions in the molten salt are first fully ion exchanged with the lithium ions in the glass; after the glass is lowered to room temperature, the second ion exchange reaction is carried out, the glass is placed in a salt solution containing potassium ions, the temperature of the salt solution is about 360-410 DEG C, and the ion exchange time is about 1.5-3h, so that the potassium ions in the molten salt are fully ion exchanged with the sodium ions and lithium ions on the surface layer of the glass.

[0023] The beneficial effects of this invention are as follows: This invention uses silica as the matrix, adding small amounts of boron oxide and lithium oxide to the formula. Additionally, a small amount of low-melting-point glass powder is added to the glass powder to achieve fluxing and increase density, reaching 99%. Furthermore, the mechanical properties of the sintered glass are improved through two chemical tempering processes. This results in 3D-printed sintered glass exhibiting high chemical stability, thermal stability, and good mechanical properties, with a maximum surface stress of 872 MPa, a maximum Vickers hardness of 690 MPa, and a bending strength of 159 MPa, meeting the technical parameter requirements of the microfluidics industry. Detailed Implementation

[0024] A method for preparing additively manufactured borosilicate glass, the specific implementation steps of which are as follows:

[0025] Examples 1 to 5:

[0026] (1) Weigh the borosilicate glass and low melting point glass according to the formulas in Table 1 respectively: Mix the borosilicate glass raw materials evenly, put them into a platinum crucible for melting, the melting temperature is 1625℃~1635℃, the specific temperature is shown in Table 1, keep it at the temperature for 2 hours, take the clear glass liquid out of the high temperature furnace, and quench it with water to obtain borosilicate glass; Mix the low melting point glass raw materials evenly, put them into an alumina crucible for melting, the melting temperature is 900℃, keep it at the temperature for 1 hour, take the clear glass liquid out of the high temperature furnace, and quench it with water to obtain low melting point glass;

[0027] (2) The two types of glass were crushed in a roller crusher to obtain glass particles with a particle size of about 1 mm. Then, borosilicate glass powder and low melting point glass powder with a particle size of about 10~30 μm were obtained by passing them through an ultrafine grinding system, a high-energy ball mill system and a precision sieving system. The two types of glass powder were mixed separately according to the proportions of Examples 1 to 5, and then mixed evenly using a mixer for later use.

[0028] (3) Prepare a slurry by mixing 89g of glass powder, 0.5g of trimethylbenzoyl-diphenylphosphine oxide (TPO), 10.5g of HDDA (1,6-hexanediamine), TMPTA (trimethylolpropionic acid trimethyl butyl ester), and EA (ethyl acrylate) (of which HDDA 6.3g, TMPTA 2.6g, and EA 1.6g). Print layer by layer by light source irradiation using the DLP method. After printing, degrease the material. The degreasing temperature regime is as follows: heat up to 550℃ at a rate of 0.5℃ / min and hold for 2.5h; then cool down to 40℃ at a rate of 1℃ / min.

[0029] (4) The sample was then placed in a vacuum furnace and evacuated for 30 minutes to a vacuum level of about 50 Pa. Then the temperature was increased to 1240°C to 1270°C at a rate of 2°C / min. The specific sintering temperatures for each embodiment are shown in Table 1. The temperature was held for 2 hours and then decreased to 40°C at a rate of 2°C / min to obtain transparent 3D printed glass.

[0030] (5) Preheat the 3D printed glass in step (4) in a muffle furnace (temperature 300℃) for 2 hours, then immerse the 3D printed glass in a sodium nitrate solution at 430℃ for 2 hours of ion exchange, so that the large-radius sodium ions in the molten salt and the small-radius lithium ions in the glass can fully exchange ions. After the reaction is completed, place the 3D printed glass in a muffle furnace at 380℃ to cool down at a rate of 5℃ / min. After the glass is cooled to room temperature, clean it and carry out the second ion exchange reaction. First, preheat the 3D printed glass in a muffle furnace (320℃) for 2 hours, then put it in a salt solution containing potassium nitrate (400℃) for about 2 hours of ion exchange, so that the large-radius potassium ions in the molten salt and the small-radius sodium and lithium ions on the glass surface can fully exchange ions. After the reaction is completed, place the 3D printed glass in a muffle furnace at 380℃ to cool down at a rate of 5℃ / min. After the glass is cooled to room temperature, clean it and set it aside.

[0031] (6) Prepare the above glass samples and conduct tests on density, transmittance, bending strength, thermal expansion and acid and alkali resistance.

[0032] Comparative Example 1 and Comparative Example 2:

[0033] The borosilicate glass powder formulations were the same as those in Examples 1 and 2, but low-melting-point glass powder was not added. The subsequent experimental steps were the same as those in Examples 1 and 2, with two chemical tempering reactions performed. The finished glass samples were then prepared and tested for density, transmittance, flexural strength, thermal expansion, and acid and alkali resistance.

[0034] Comparative Example 3 and Comparative Example 4:

[0035] The formulations of borosilicate glass powder and low melting point glass powder were the same as those in Examples 1 and 2, respectively, but only one chemical tempering reaction was carried out. The finished glass samples were prepared and tested for density, transmittance, bending strength, thermal expansion and acid and alkali resistance.

[0036] Comparative Example 5 and Comparative Example 6:

[0037] The formulations of borosilicate glass powder and low-melting-point glass powder are the same as those in Examples 1 and 2, respectively. The preparation steps (1) to (4) are the same, except that the order of the salt solutions for the two ion exchanges in (5) is reversed. First, the glass is placed in a salt solution containing potassium nitrate (400°C) for about 2 hours for ion exchange. After cleaning and drying, the glass is then immersed in a sodium nitrate solution at 430°C for 2 hours for ion exchange. The remaining steps are exactly the same. Samples of the finished glass are prepared and tested for density, transmittance, bending strength, thermal expansion, and acid and alkali resistance.

[0038] Table 1 shows that the glass printed using the method of this invention in Examples 1-5 has a high density, reaching up to 99%, and a visible light transmittance of up to 80.7%. After two chemical tempering processes, the glass exhibits high surface stress and Vickers hardness, with a maximum surface stress of 872 MPa, a maximum Vickers hardness of 690 MPa, and a maximum flexural strength of 159 MPa. It possesses good mechanical and thermal properties, minimal mass loss in acid and alkali resistance tests, and good chemical stability. Table 2 shows that Comparative Examples 1 and 2, which did not add low-melting-point glass powder, showed a significant decrease in glass density after sintering, leading to a substantial reduction in optical properties, mechanical properties, and chemical stability. Comparative Examples 3 and 4, which only underwent the first chemical tempering process, showed varying degrees of reduction in surface stress, Vickers hardness, and flexural strength, as shown in Table 2. Comparative Examples 5 and 6, where the order of the two chemical tempering reactions was reversed, also showed varying degrees of reduction in surface stress, Vickers hardness, and flexural strength, as shown in Table 2.

[0039]

Claims

1. An additively manufactured borosilicate glass, characterized in that... It is made from the following raw materials in the following mass percentages: 82-92% mixed glass powder, 0.15-0.5% photoinitiator, and 5-19% photosensitive resin, wherein the mixed glass powder consists of 95-98% main glass powder and 2-5% low-melting-point glass powder; the main glass powder, by mass percentage, consists of the following raw materials: 88-93 wt% SiO2, 5-9 wt% B2O3, 1.2-5 wt% Li2O, and 0.5-1.5 wt% Ba(NO3)2, wherein 6.5 wt% ≤ B2O3 + Li2O ≤ 13.0 wt%; the low-melting-point glass powder consists of the following raw materials: 65-75 wt% Bi2O3, 7-13 wt% B2O3, 8-12 wt% ZnO, 4-8 wt% BaO, and 0.5-3 wt% SiO2.

2. The additive manufacturing borosilicate glass according to claim 1, characterized in that: The mixed glass powder consists of 96-98% main glass powder and 2-4% low melting point glass powder.

3. The additively manufactured borosilicate glass according to claim 1, characterized in that: The photoinitiator is trimethylbenzoyl-diphenylphosphine oxide.

4. The additively manufactured borosilicate glass according to claim 1, characterized in that: The photosensitive resin is a mixture of 1,6-hexanediamine, trimethylolpropionic acid trimethacrylate, and ethyl acrylate.

5. A method for preparing additively manufactured borosilicate glass, characterized in that... Includes the following steps: (1) Weigh the raw materials according to the following mass percentages: SiO2 88~93 wt%, B2O3 5~9 wt%, Li2O 1.2~5 wt% and Ba(NO3)2 0.5~1.5 wt%, of which 6.5wt%≤B2O3+ Li2O≤13.0 wt%. Mix them evenly and then melt them at a melting temperature of 1625℃~1635℃. After melting, grind the glass block into micron-sized powder as the main glass powder. (2) Weigh the raw materials according to the following mass percentages: Bi2O3 65~75 wt%, B2O3 7~13 wt%, ZnO 8~12 wt%, BaO 4~8 wt% and SiO2 0.5~3 wt%, mix them evenly and then melt them at a melting temperature of 850~900℃. After melting, grind the glass block into micron-sized powder as low melting point glass powder. (3) Mix the main glass powder and low melting point glass powder at a mass ratio of 95~98:2~5 to obtain a mixture, and then mix the mixture, photoinitiator and photosensitive resin at a mass ratio of 82~92:0.15~0.5:5~19 to prepare a slurry; (4) 3D printing is performed using photopolymerization. After printing, degreasing is performed. The degreasing temperature regime is as follows: heat up to 540~580℃ at a rate of 0.5℃ / min and hold for 2~3h; then cool down to 40℃ at a rate of 1℃ / min; after degreasing, vacuum sintering is performed. The vacuum degree is evacuated to 45~55Pa, and the temperature is increased to 1240~1270℃ at a rate of 2℃ / min and held for 2~3h. Then the temperature is reduced to 40℃ at a rate of 2℃ / min to obtain transparent 3D printed glass. (5) The 3D printed glass is subjected to two ion exchange reactions. First, the 3D printed glass preheated to 320°C is immersed in a sodium nitrate solution at 400°C to 450°C for 1.5 to 3 hours to allow the sodium ions in the molten salt to fully exchange with the lithium ions in the glass. After the reaction is completed, the glass is placed in a muffle furnace at 380°C to cool down at a rate of 5°C / min. After the glass is cooled to room temperature, it is cleaned and dried using an ultrasonic instrument. Then, the second ion exchange reaction is carried out. The 3D printed glass preheated to 300°C is placed in a potassium nitrate solution at 360°C to 410°C for 1.5 to 3 hours to allow the potassium ions in the molten salt to fully exchange with the sodium and lithium ions on the glass surface. After the reaction is completed, the glass is placed in a muffle furnace at 380°C to cool down at a rate of 5°C / min. After the reaction is completed, it is cleaned.

6. The method for preparing additively manufactured borosilicate glass according to claim 5, characterized in that: The particle size of the micron-sized powder in steps (1) and (2) is 10~30μm.

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