A high borosilicate glass tube and its continuous hot pressing process

Abstract

This invention belongs to the field of glass manufacturing and discloses a high borosilicate glass tube and its continuous hot-pressing forming process. The tube body comprises, by weight percentage, the following raw materials: boron trioxide 18%-19%, aluminum oxide 3%-4.5%, zinc oxide 2%-4%, sodium oxide 1%-2%, potassium oxide 0.5%-1.5%, gallium oxide 0.5%-2%, lanthanum oxide 0.1%-1.5%, and yttrium oxide 0.1%-1%. It also contains 0.05%-0.3% cerium oxide and 0.02%-0.1% nano-titanium carbide and the balance silicon dioxide; the wall thickness of the tube is 0.8-2.0 mm and the outer diameter is 10-50 mm; the purpose of this invention is to provide a high borosilicate glass tube with a lower coefficient of thermal expansion, higher chemical stability and mechanical strength, as well as a continuous hot pressing process that can achieve efficient and stable production and improve product quality.

Description

Technical Field

[0001] This invention relates to the field of glass manufacturing technology, specifically to a high borosilicate glass tube and its continuous hot pressing process. Background Technology

[0002] High borosilicate glass tubes are widely used in laboratory instruments, solar collectors, and medical equipment due to their excellent heat resistance, chemical stability, and mechanical strength. Traditional high borosilicate glass tubes are primarily composed of silicon dioxide and boron trioxide as basic raw materials. However, with the continuous expansion of applications, higher requirements are being placed on their performance, such as lower thermal expansion coefficients and higher chemical stability.

[0003] Meanwhile, existing high borosilicate glass tube forming processes suffer from problems such as low production efficiency and unstable product quality. For example, the furnace lining is easily corroded by molten glass, resulting in a short service life, and the forming mold has insufficient control over the forming precision of the glass tube.

[0004] Therefore, a high borosilicate glass tube with superior performance and its efficient and stable molding process were proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a high borosilicate glass tube with a lower coefficient of thermal expansion, higher chemical stability and mechanical strength, as well as a continuous hot pressing process that enables efficient and stable production and improves product quality.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The technical solution provided by this invention is: a high borosilicate glass tube, comprising a tube body, wherein the raw materials of the tube body, by weight percentage, include: 18%-19% boron trioxide, 3%-4.5% aluminum oxide, 2%-4% zinc oxide, 1%-2% sodium oxide, 0.5%-1.5% potassium oxide, 0.5%-2% gallium oxide, 0.1%-1.5% lanthanum oxide, and 0.1%-1% yttrium oxide; the raw materials of the tube body also contain 0.05%-0.3% cerium oxide and 0.02%-0.1% nano-titanium carbide and the balance silicon dioxide; the wall thickness of the tube body is 0.8-2.0 mm, and the outer diameter is 10-50 mm.

[0008] Furthermore, the outer wall of the tube is coated with a zirconium diboride ceramic coating with a thickness of 8-20 μm. The coating is prepared by plasma chemical vapor deposition. The bonding strength between the coating and the tube is ≥60 MPa, and the surface hardness is ≥2000 HV.

[0009] A continuous hot-pressing process for producing high borosilicate glass tubes according to any one of claims 1-3, the process comprising the following steps:

[0010] S1. Raw material preparation: Mix silicon dioxide, boron trioxide, aluminum oxide, zinc oxide, sodium oxide, potassium oxide, gallium oxide, lanthanum oxide, and yttrium oxide in a certain proportion. Optionally, cerium oxide and nano-titanium carbide may be added to obtain a mixture.

[0011] S2. Melting: The mixture is put into a furnace and melted at 1550-1650℃ to obtain molten glass. The furnace lining is made of boron nitride-silicon carbide composite refractory material, in which the boron nitride content is 20%-30% and the silicon carbide content is 70%-80%.

[0012] S3. Continuous hot pressing: Molten glass is conveyed to the forming mold through the flow channel. The forming mold includes an upper mold and a lower mold, and a forming cavity adapted to the outer diameter of the high borosilicate glass tube is formed between the upper mold and the lower mold. During the forming process, the upper mold moves downward at a speed of 0.6-1.4 mm / s, applying a pressure of 0.6-1.4 MPa to the molten glass. At the same time, the temperature of the forming mold is controlled at 820-980℃ by a heating device, so that the molten glass is formed into a glass tube blank in the forming cavity. The inner wall of the flow channel is provided with a zirconium diboride ceramic coating with a thickness of 0.3-0.7 mm.

[0013] S4. Cooling and Shaping: After forming, the glass preform moves to the cooling area along with the forming mold. Cool air at a temperature of 15-35℃ and a wind speed of 7-12m / s is blown onto the glass preform by a cooling fan, so that the glass preform is cooled to room temperature at a rate of 6-14℃ / min.

[0014] S5. Cutting: Cut the cooled and shaped glass tube blank to a predetermined length to obtain a high borosilicate glass tube.

[0015] Furthermore, in step S2, the boron nitride-silicon carbide composite refractory material is formed by isostatic pressing, with a density ≥2.8g / cm³, and an erosion rate of ≤0.05mm / h on high borosilicate glass melt at 1600℃. This composite refractory material can effectively improve the service life of the furnace lining and reduce glass melt contamination caused by lining erosion.

[0016] Furthermore, in step S3, the zirconium diboride ceramic coating is prepared by supersonic plasma spraying. The coating has a ZrB2 phase content of ≥95%, a porosity of ≤2%, and a thermal shock resistance (1000℃ water cooling cycle) of ≥50 times. The zirconium diboride ceramic coating can improve the erosion resistance and thermal stability of the material flow channel and ensure the stable delivery of molten glass.

[0017] Furthermore, in step S4, the conveyor rollers in the cooling area are made of graphite-carbon fiber composite material, and the surface is impregnated with polytetrafluoroethylene, with a friction coefficient ≤0.15. This can reduce frictional damage to the glass preform during the cooling process and ensure product quality.

[0018] Furthermore, in step S5, the cutting equipment adopts a diamond wire saw and laser composite cutting device. The wire saw feed speed is 15-25 mm / s, the laser preheating temperature is 300-500℃, and the parallelism of the cutting end face is ≤0.05 mm. The composite cutting device can improve cutting accuracy and efficiency and reduce cutting defects.

[0019] The beneficial effects of this technical solution are:

[0020] (1) The thermal stability was optimized by adding gallium oxide to the raw material of high borosilicate glass tubes. Gallium oxide can effectively reduce the coefficient of thermal expansion of glass. No cracks were generated after 200 cycles at a temperature of 250℃ to -40℃. At the same time, the introduction of lanthanum oxide and yttrium oxide reduced the coefficient of thermal expansion of glass to 2.0-2.8×10. -6 The temperature is significantly lower than that of traditional high borosilicate glass, while the bending strength is increased to 280-350MPa, which greatly improves the reliability of the glass tube in environments with drastic temperature changes. It can be used in scenarios with extremely high requirements for thermal stability, such as observation windows in high-temperature furnaces and protective sleeves for high-temperature sensors in the aerospace field.

[0021] Cerium oxide releases oxygen to eliminate bubbles in molten glass, improving light transmittance; nano-titanium carbide forms a nano-reinforcing skeleton, improving wear resistance.

[0022] The zinc oxide and aluminum oxide components in the raw materials work synergistically with gallium oxide to improve the network structure of the glass, significantly enhancing the chemical stability of the glass tube. Acid and alkali corrosion tests show that the glass tube of this invention exhibits significantly improved resistance to acid and alkali corrosion compared to traditional high borosilicate glass tubes under the same conditions, making it suitable for applications requiring high chemical stability, such as linings for chemical reactors and pipelines for transporting corrosive liquids.

[0023] (2) The zirconium diboride ceramic coating on the outer wall of the tube is prepared by plasma chemical vapor deposition and has extremely high surface hardness (≥2000HV) and good bonding strength (≥60MPa). In practical use, compared with uncoated glass tubes, it effectively extends the service life of the glass tube and is suitable for occasions that require frequent friction contact, such as glass guide tubes in machining.

[0024] Zirconium diboride ceramic coating exhibits excellent corrosion resistance to various chemical reagents. In environments with strong oxidizing acids and strong alkalis, it can effectively protect the glass tube body from corrosion, further expanding the application range of glass tubes. It can be used in instruments for detecting highly corrosive media in chemical, environmental protection and other fields.

[0025] (3) In the continuous hot pressing process, the upper mold moving speed (0.6-1.4 mm / s), pressure (0.6-1.4 MPa), and forming mold temperature (820-980℃) are precisely controlled to enable the molten glass to be formed into a glass tube blank quickly and stably in the forming cavity, which improves production efficiency compared with the traditional forming process. At the same time, the cooling zone is controlled by cooling fans and reasonable wind speed (7-12 m / s) and temperature (15-35℃) to enable the glass tube blank to be cooled and shaped at an appropriate speed (6-14℃ / min), avoiding product defects caused by improper cooling, and further improving production efficiency and product qualification rate.

[0026] (4) The furnace lining is made of boron nitride-silicon carbide composite refractory material, which has an erosion rate of ≤0.05mm / h on high borosilicate glass melt at 1600℃, and its service life is more than twice that of traditional refractory materials, reducing the replacement frequency and cost of the furnace lining. The zirconium diboride ceramic coating on the inner wall of the material flow channel has a thermal shock resistance (1000℃ water cooling cycle) ≥50 times, effectively preventing the glass melt from eroding and adhering to the channel, and reducing cleaning and maintenance costs. In addition, the optimization of process parameters and the improvement of equipment performance have reduced energy consumption.

[0027] (5) By adopting a diamond wire saw and laser composite cutting device, the parallelism of the cutting end face is ≤0.05mm, the cutting accuracy is greatly improved, and the product scrap rate caused by cutting defects is reduced. The conveyor rollers in the cooling area are made of graphite-carbon fiber composite material and impregnated with polytetrafluoroethylene, with a friction coefficient ≤0.15, which avoids scratches and damage caused by friction during the cooling process of glass tube blanks, ensures the appearance quality and dimensional accuracy of the products, and significantly improves the stability of product quality. Attached Figure Description

[0028] Figure 1 This is a flowchart of a high borosilicate glass tube and its continuous hot pressing process proposed in this invention;

[0029] Figure 2 This is a data table for Example 1 of the high borosilicate glass tube and its continuous hot pressing process proposed in this invention;

[0030] Figure 3 This is a data table for Example 2 of the high borosilicate glass tube and its continuous hot pressing process proposed in this invention;

[0031] Figure 4 This is a data table for Example 3 of the high borosilicate glass tube and its continuous hot pressing process proposed in this invention;

[0032] Figure 5 This is a data table for Example 4 of the high borosilicate glass tube and its continuous hot pressing process proposed in this invention;

[0033] Figure 6 This is a data table for Example 5 of the high borosilicate glass tube and its continuous hot pressing process proposed in this invention;

[0034] Figure 7 This is a data comparison table of various embodiments of the high borosilicate glass tube and its continuous hot pressing process proposed in this invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0036] The specific implementation process is as follows:

[0037] Example 1:

[0038] Please see Figure 1-2 The present invention provides a technical solution: a high borosilicate glass tube and its continuous hot-pressing forming process, comprising the following steps:

[0039] S1. Raw material preparation: By weight percentage, 19% boron trioxide, 3% aluminum oxide, 4% zinc oxide, 1% sodium oxide, 1.5% potassium oxide, 2% gallium oxide, 0.1% lanthanum oxide, 0.1% yttrium oxide, 0.05% cerium oxide, 0.02% nano titanium carbide, and the balance silicon dioxide are mixed thoroughly to obtain a mixture.

[0040] S2. Melting: The mixture is added to a lining of boron nitride-silicon carbide composite refractory (20% boron nitride content, 80% silicon carbide content, formed by isostatic pressing, density 2.8 g / cm³). 3 In a furnace with an erosion rate of 0.05 mm / h on the high borosilicate glass melt at 1600℃, the melt was obtained by melting at 1550℃.

[0041] S3. Continuous hot pressing: The molten glass is conveyed to the forming mold through a flow channel with a 0.3mm thick zirconium diboride ceramic coating (prepared by supersonic plasma spraying, with a ZrB2 phase content of 95%, porosity of 2%, and thermal shock resistance (1000℃ water cooling cycle) of 50 times) on the inner wall. A forming cavity is formed between the upper and lower molds of the forming mold, which is adapted to the high borosilicate glass tube with an outer diameter of 10mm and a wall thickness of 0.8mm. The upper mold moves downward at a speed of 0.6mm / s, applying a pressure of 0.6MPa to the molten glass. At the same time, the temperature of the forming mold is controlled at 820℃ by a heating device, so that the molten glass is formed into a glass tube blank in the forming cavity.

[0042] S4. Cooling and Shaping: After forming, the glass preform moves to the cooling area along with the forming mold. The cooling fan blows cold air at a temperature of 15℃ and a wind speed of 7m / s onto the glass preform, so that the glass preform cools to room temperature at a rate of 6℃ / min. The conveyor rollers in the cooling area are made of graphite-carbon fiber composite material and the surface is impregnated with polytetrafluoroethylene, with a friction coefficient of 0.15.

[0043] S5. Cutting: A diamond wire saw and laser composite cutting device is used. The wire saw feed speed is 15mm / s and the laser preheating temperature is 300℃. The cooled and shaped glass tube blank is cut to the predetermined length to obtain a high borosilicate glass tube.

[0044] This embodiment focuses on basic heat resistance as the core objective, supplemented by 3% alumina and 4% zinc oxide to enhance chemical stability and mechanical strength. The newly added lanthanum oxide (0.1%) and yttrium oxide (0.1%), through the network filling effect of rare earth ions, initially improve the thermal stability of the glass, keeping the coefficient of thermal expansion controlled at 3.3 × 10⁻⁶. -6 The glass exhibits no cracks after 200 temperature cycles from 250℃ to -40℃, meeting the requirements for typical scenarios with drastic temperature changes. Trace amounts of cerium oxide (0.05%) act as a clarifying agent, effectively reducing bubbles in the molten glass and improving matrix transparency, while the dispersed distribution of nano-titanium carbide (0.02%) provides initial wear-resistant reinforcement to the glass matrix.

[0045] During the preparation process, a low-temperature melting of 1550℃ and low-pressure molding of 0.6MPa were used, along with a mold temperature of 820℃. Although this reduced energy consumption, it resulted in insufficient fluidity of the molten glass, leading to poor surface smoothness and a surface hardness of only 580HV after molding. The cooling process used 15℃ cold air at a wind speed of 7m / s to control the cooling rate at 6℃ / min, avoiding internal stress concentration. However, the low-pressure molding resulted in a coating bonding strength of only 60MPa, limiting the improvement in wear resistance.

[0046] The advantage of this embodiment lies in the first-time verification of the compatibility between the rare earth-micro-nano composite system and traditional borosilicate glass. It features a balanced proportion of basic components and reduces raw material costs by 18% compared to functional formulations. It is suitable for applications where surface quality requirements are not high and basic heat resistance is emphasized, such as ordinary laboratory beakers and reagent tubes, achieving reliable temperature adaptability at low cost.

[0047] Example 2:

[0048] Please see Figure 1 and Figure 3 The present invention provides a technical solution: a high borosilicate glass tube and its continuous hot-pressing forming process, comprising the following steps:

[0049] S1. Raw material preparation: By weight percentage, the following raw materials are prepared: 18% boron trioxide, 4.5% aluminum oxide, 2% zinc oxide, 2% sodium oxide, 0.5% potassium oxide, 0.5% gallium oxide, 1.5% lanthanum oxide, 1% yttrium oxide, 0.3% cerium oxide, 0.1% nano titanium carbide, and the balance silicon dioxide. Mix the raw materials thoroughly to obtain a mixture.

[0050] S2. Melting: The mixture is added to a lining of boron nitride-silicon carbide composite refractory (boron nitride content 30%, silicon carbide content 70%, formed by isostatic pressing, density 2.9 g / cm³). 3 In a furnace with an erosion rate of 0.04 mm / h on the high borosilicate glass melt at 1600℃, the glass melt was melted at 1650℃ to obtain the glass melt.

[0051] S3. Continuous hot pressing: The molten glass is conveyed to the forming mold through a flow channel with a 0.7mm thick zirconium diboride ceramic coating (prepared by supersonic plasma spraying, with a ZrB2 phase content of 96%, a porosity of 1.5%, and thermal shock resistance (1000℃ water cooling cycle) of 52 times) on the inner wall. A forming cavity is formed between the upper and lower molds of the forming mold, which is adapted to the high borosilicate glass tube with an outer diameter of 50mm and a wall thickness of 2.0mm. The upper mold moves downward at a speed of 1.4mm / s, applying a pressure of 1.4MPa to the molten glass. At the same time, the temperature of the forming mold is controlled at 980℃ by a heating device, so that the molten glass is formed into a glass tube blank in the forming cavity.

[0052] S4. Cooling and Shaping: After forming, the glass preform moves to the cooling area along with the forming mold. The cooling fan blows cold air at a temperature of 35℃ and a wind speed of 12m / s onto the glass preform, so that the glass preform cools to room temperature at a rate of 14℃ / min. The conveyor rollers in the cooling area are made of graphite-carbon fiber composite material, and the surface is impregnated with polytetrafluoroethylene, with a friction coefficient of 0.14.

[0053] S5. Cutting: A diamond wire saw and laser composite cutting device is used. The wire saw feed speed is 25mm / s and the laser preheating temperature is 500℃. The cooled and shaped glass tube blank is cut to the predetermined length to obtain a high borosilicate glass tube.

[0054] Example 2 focuses on high-end optical performance and extreme thermal stability. By introducing lanthanum oxide (1.5%) and yttrium oxide (1%) at the upper limit concentration, and utilizing the strong bonding effect of rare earth ions, the coefficient of thermal expansion is reduced to 2.5 × 10⁻⁶. -6 / ℃, reaching aerospace-grade heat resistance standards. The addition of 0.3% cerium oxide significantly improves the glass purity, with a light transmittance of 95%, and absorbs 200-300nm ultraviolet light through 4f electron transition characteristics. Combined with the nano-reinforcing effect of 0.1% nano titanium carbide, the matrix hardness is increased to 620HV, providing a more stable bonding substrate for the outer zirconium diboride coating.

[0055] During the preparation process, a high-temperature melting of 1650℃ and high-pressure molding of 1.4MPa are used, combined with a mold temperature of 980℃. This significantly improves the fluidity of the molten glass and the molding accuracy, with the outer diameter deviation controlled within ±0.04mm. However, the high temperature and high pressure result in a 25% increase in energy consumption compared to traditional processes. The cooling process uses 35℃ hot air at a wind speed of 12m / s for rapid cooling at a cooling rate of 14℃ / min. This shortens the production cycle while ensuring that the coating bonding strength reaches 65MPa, the surface hardness reaches 2050HV, and the acid and alkali corrosion resistance is improved by 60% compared to traditional glass.

[0056] The technological breakthrough of this embodiment lies in the deep synergy between rare earth elements and micro / nano materials, achieving an infrared shielding rate (8-14μm) of 60%, which is suitable for the optical window of infrared detection equipment.

[0057] Example 3:

[0058] Please see Figure 1 and Figure 4 The present invention provides a technical solution: a high borosilicate glass tube and its continuous hot-pressing forming process, comprising the following steps:

[0059] S1. Raw material preparation: By weight percentage, 19% boron trioxide, 4% aluminum oxide, 3% zinc oxide, 1.5% sodium oxide, 1% potassium oxide, 1% gallium oxide, 0.8% lanthanum oxide, 0.6% yttrium oxide, 0.15% cerium oxide, 0.08% nano titanium carbide, and the balance silicon dioxide are mixed thoroughly to obtain a mixture.

[0060] S2. Melting: The mixture is put into a furnace lined with boron nitride-silicon carbide composite refractory material (boron nitride content 25%, silicon carbide content 75%, formed by isostatic pressing, density 2.85g / cm³, erosion rate of high borosilicate glass melt at 1600℃ 0.045mm / h), and melted at 1600℃ to obtain glass melt;

[0061] S3. Continuous hot pressing: The molten glass is conveyed to the forming mold through a flow channel with a 0.5mm thick zirconium diboride ceramic coating (prepared by supersonic plasma spraying, with a ZrB2 phase content of 95.5%, a porosity of 1.8%, and thermal shock resistance (1000℃ water cooling cycle) of 51 times) on the inner wall. A forming cavity is formed between the upper and lower molds of the forming mold, which is adapted to the high borosilicate glass tube with an outer diameter of 30mm and a wall thickness of 1.5mm. The upper mold moves downward at a speed of 1.0mm / s, applying a pressure of 1.0MPa to the molten glass. At the same time, the temperature of the forming mold is controlled at 900℃ by a heating device, so that the molten glass is formed into a glass tube blank in the forming cavity.

[0062] S4. Cooling and Shaping: After forming, the glass preform moves to the cooling area along with the forming mold. The cooling fan blows cold air at a temperature of 25℃ and a wind speed of 9m / s onto the glass preform, so that the glass preform cools to room temperature at a rate of 10℃ / min. The conveyor rollers in the cooling area are made of graphite-carbon fiber composite material, and the surface is impregnated with polytetrafluoroethylene, with a friction coefficient of 0.145.

[0063] S5. Cutting: A diamond wire saw and laser composite cutting device is used. The wire saw feed speed is 20mm / s and the laser preheating temperature is 400℃. The cooled and shaped glass tube blank is cut to the predetermined length to obtain a high borosilicate glass tube.

[0064] As a comprehensive performance optimization scheme, Example 3 uses 4% alumina and 3% zinc oxide to form a composite network intermediate, combined with a moderate concentration of 0.8% lanthanum oxide and 0.6% yttrium oxide, which reduces the coefficient of thermal expansion (2.8 × 10⁻⁶). -6 While avoiding excessive rare earth elements (at / ℃), the synergistic effect of 0.15% cerium oxide and 0.08% nano-titanium carbide reduces the bubble rate of the glass melt by 40% and improves the wear resistance by 35%, thus constructing a ternary composite system of "clarification-reinforcement-thermal stability".

[0065] During the preparation process, a melting temperature of 1600℃ and a forming pressure of 1.0MPa form the optimal process window. A mold temperature of 900℃ ensures uniform filling of the forming cavity with molten glass, an outer diameter accuracy of ±0.03mm, and a cutting end face parallelism of ≤0.04mm. The cooling process utilizes ambient air at 25℃ and a wind speed of 9m / s to control the cooling rate at 10℃ / min, preventing coating peeling caused by rapid cooling. The coating adhesion strength is 63MPa, and the surface hardness is 2020HV. Acid and alkali corrosion tests show a weight loss of only 0.18mg / cm³ after 24 hours. 2 It is 75% better than traditional glass.

[0066] The advantage of this embodiment lies in the balanced optimization of composition and process parameters. It exhibits no significant shortcomings in thermal stability, mechanical strength, chemical stability, and optical performance, and its energy consumption is reduced by 18% compared to Embodiment 2, while raw material costs are kept within a reasonable range. It is suitable for mainstream markets with high comprehensive performance requirements, such as solar collector tubes, medical device conduits, and chemical corrosion-resistant pipes. It combines technological advantages with mass production feasibility, and has broad industrial application prospects.

[0067] Example 4:

[0068] Please see Figure 1 and Figure 5 The present invention provides a technical solution: a high borosilicate glass tube and its continuous hot-pressing forming process, comprising the following steps:

[0069] S1. Raw material preparation: By weight percentage, the following raw materials are prepared: 19% boron trioxide, 4.5% aluminum oxide, 3% zinc oxide, 1.2% sodium oxide, 1.3% potassium oxide, 1.2% gallium oxide, 0.3% lanthanum oxide, 0.2% yttrium oxide, 0.07% cerium oxide, 0.03% nano titanium carbide, and the balance silicon dioxide. The raw materials are thoroughly mixed to obtain a mixture.

[0070] S2. Melting: The mixture is added to a lining of boron nitride-silicon carbide composite refractory (boron nitride content 22%, silicon carbide content 78%, formed by isostatic pressing, density 2.82 g / cm³). 3 In a furnace with an erosion rate of 0.048 mm / h on the high borosilicate glass melt at 1600℃, the glass melt was melted at 1580℃ to obtain the glass melt.

[0071] S3. Continuous hot pressing: The molten glass is conveyed to the forming mold through a flow channel with a 0.4mm thick zirconium diboride ceramic coating (prepared by supersonic plasma spraying, with a ZrB2 phase content of 95.2%, porosity of 1.9%, and thermal shock resistance (1000℃ water cooling cycle) of 50 times) on the inner wall. A forming cavity is formed between the upper and lower molds of the forming mold, which is adapted to the high borosilicate glass tube with an outer diameter of 20mm and a wall thickness of 1.2mm. The upper mold moves downward at a speed of 0.8mm / s, applying a pressure of 0.8MPa to the molten glass. At the same time, the temperature of the forming mold is controlled at 850℃ by a heating device, so that the molten glass is formed into a glass tube blank in the forming cavity.

[0072] S4. Cooling and Shaping: After forming, the glass preform moves to the cooling area along with the forming mold. The cooling fan blows cold air at a temperature of 20℃ and a wind speed of 8m / s onto the glass preform, so that the glass preform cools to room temperature at a rate of 8℃ / min. The conveyor rollers in the cooling area are made of graphite-carbon fiber composite material, and the surface is impregnated with polytetrafluoroethylene, with a friction coefficient of 0.148.

[0073] S5. Cutting: A diamond wire saw and laser composite cutting device is used. The wire saw feed speed is 18mm / s and the laser preheating temperature is 350℃. The cooled and shaped glass tube blank is cut to the predetermined length to obtain a high borosilicate glass tube.

[0074] Example 4 focuses on high dimensional accuracy and molding stability, combining low-concentration rare earth elements (0.3% lanthanum oxide, 0.2% yttrium oxide) with micro / nano materials (0.07% cerium oxide, 0.03% nano-titanium carbide) and the balance silica. This ensures the fluidity of the molten glass while reducing the impact of compositional fluctuations on molding accuracy. 4.5% alumina and 3% zinc oxide enhance structural rigidity, ensuring that the outer diameter deviation of the glass tube remains stable within ±0.02mm at a mold movement speed of 0.8mm / s, meeting the stringent dimensional requirements of industrial pipelines.

[0075] During the preparation process, a medium-temperature melting temperature of 1580℃ and a forming pressure of 0.8MPa, combined with a mold temperature of 850℃, effectively control the flow inertia of the molten glass. A 0.4mm thick zirconium diboride coating on the inner wall of the flow channel reduces glass adhesion, further improving forming consistency. The cooling process uses 20℃ cold air at a wind speed of 8m / s, with a cooling rate of 8℃ / min, to avoid uneven dimensional shrinkage caused by temperature gradients. The conveyor rollers have a friction coefficient of 0.148, ensuring the glass preform is free of scratches and damage. The finished product has a coefficient of thermal expansion of 3.0×10⁻⁶. -6 / ℃, although lower than traditional glass but higher than functional formulations, the infrared shielding rate is only 20%, and the optical performance is relatively weak.

[0076] The key technical advantage of this embodiment is that it achieves high-precision molding of ±0.02mm through component simplification and process fine-tuning, reducing production costs by 15% compared to similar products, making it suitable for large-scale industrial production. The disadvantage is the sacrifice of some thermal stability and optical performance. It is suitable for applications such as mechanical guide tubes and industrial sight glasses, where dimensional accuracy requirements are high but optical performance requirements are not. It has significant advantages in the field of glass components for automated production lines.

[0077] Example 5:

[0078] Please see Figure 1 and Figure 6 The present invention provides a technical solution: a high borosilicate glass tube and its continuous hot-pressing forming process, comprising the following steps:

[0079] S1. Raw material preparation: By weight percentage, the following raw materials are prepared: 18% boron trioxide, 3.5% aluminum oxide, 4% zinc oxide, 1% sodium oxide, 1.3% potassium oxide, 1.5% gallium oxide, 1.2% lanthanum oxide, 0.8% yttrium oxide, 0.25% cerium oxide, 0.05% nano titanium carbide, and the balance silicon dioxide. Mix the raw materials thoroughly to obtain a mixture.

[0080] S2. Melting: The mixture is put into a furnace lined with boron nitride-silicon carbide composite refractory material (boron nitride content 28%, silicon carbide content 72%, formed by isostatic pressing, density 2.88 g / cm³, erosion rate of high borosilicate glass melt at 1600℃ 0.042 mm / h), and melted at 1620℃ to obtain glass melt;

[0081] S3. Continuous hot pressing: The molten glass is conveyed to the forming mold through a flow channel with a 0.6mm thick zirconium diboride ceramic coating (prepared by supersonic plasma spraying, with a ZrB2 phase content of 95.8%, a porosity of 1.6%, and thermal shock resistance (1000℃ water cooling cycle) of 52 times) on the inner wall. A forming cavity is formed between the upper and lower molds of the forming mold, which is adapted to the high borosilicate glass tube with an outer diameter of 40mm and a wall thickness of 1.8mm. The upper mold moves downward at a speed of 1.2mm / s, applying a pressure of 1.2MPa to the molten glass. At the same time, the temperature of the forming mold is controlled at 950℃ by a heating device, so that the molten glass is formed into a glass tube blank in the forming cavity.

[0082] S4. Cooling and Shaping: After forming, the glass preform moves to the cooling area along with the forming mold. The cooling fan blows cold air at a temperature of 30℃ and a wind speed of 10m / s onto the glass preform, so that the glass preform cools to room temperature at a rate of 12℃ / min. The conveyor rollers in the cooling area are made of graphite-carbon fiber composite material, and the surface is impregnated with polytetrafluoroethylene, with a friction coefficient of 0.142.

[0083] S5. Cutting: A diamond wire saw and laser composite cutting device is used. The wire saw feed speed is 22mm / s and the laser preheating temperature is 450℃. The cooled and shaped glass tube blank is cut to the predetermined length to obtain a high borosilicate glass tube.

[0084] As a flagship solution for infrared shielding and high-temperature resistance, Example 5 combines high-concentration lanthanum oxide (1.2%) and yttrium oxide (0.8%), utilizing the broadband absorption characteristics of rare earth ions to achieve a shielding rate of 85% in the 8-14μm infrared band, while simultaneously reducing the coefficient of thermal expansion to 2.6 × 10⁻⁶. -3 The temperature is close to that of quartz glass, and it can withstand 50 water-cooling cycles at 1200℃ without cracking. The 0.25% cerium oxide deep-clarified glass melt has a light transmittance of 96%, and the 0.05% nano titanium carbide forms a nanoscale reinforcing phase in the matrix, which increases the bending strength to 320MPa and provides a stronger substrate support for the coating.

[0085] During the preparation process, a high-temperature melting temperature of 1620℃ and a forming pressure of 1.2MPa, combined with a mold temperature of 950℃, ensure that the high-viscosity molten glass fully fills the forming cavity. The coating of the flow channel has a thermal shock resistance of 52 cycles, ensuring stable delivery under high-temperature conditions. In the cooling process, a cooling rate of 12℃ / min is controlled by 30℃ warm air and a wind speed of 10m / s to prevent rare earth components from precipitating due to rapid cooling. The coating has a bonding strength of 64MPa, a surface hardness of 2090HV, and an 80% improvement in resistance to strong oxidizing acids (such as 98% concentrated sulfuric acid).

[0086] The core advantage of this embodiment lies in the deep synergy of "rare earth optical modulation + nanostructure enhancement," which breaks through the infrared shielding limit of traditional high borosilicate glass while also possessing ultra-high heat resistance and wear resistance. It is suitable for cutting-edge fields such as optical windows for infrared spectrometers, temperature measuring tubes for aero-engines, and corrosion-resistant sleeves in the nuclear industry, providing key material support for high-end equipment manufacturing.

[0087] Methods for obtaining experimental data

[0088] 1. Raw material composition analysis: X-ray fluorescence spectrometry (XRF) was used to detect the composition of the glass tube raw materials and finished products of each embodiment. By comparing and calibrating with standard samples, the accuracy of the composition detection was ensured to reach ±0.1% (weight percentage) to verify whether the raw material ratio meets the design requirements.

[0089] 2. Physical Performance Testing: Determination of Coefficient of Thermal Expansion: Using a thermomechanical analyzer (TMA), the glass tube sample was cut into 5mm × 5mm × 20mm pieces. Heating was performed within the temperature range of 20℃-300℃ at a heating rate of 5℃ / min. The change in sample length with temperature was recorded. The coefficient of thermal expansion was calculated using the formula, with a test accuracy of ±0.1×10⁻⁶. -6 / ℃;

[0090] 3. Thermal shock resistance test: The glass tube is heated to 250°C in a high-temperature furnace and held at that temperature for 30 minutes. Then it is quickly immersed in a coolant at -40°C. This cycle is repeated 200 times. The surface of the glass tube is observed through an optical microscope to see if cracks appear, and its thermal shock resistance is evaluated.

[0091] 4. Hardness test: Using a Vickers hardness tester, apply a 200g load to the outer wall of the glass tube, hold for 15 seconds, measure the diagonal length of the indentation, and calculate the surface hardness. Take the average value of 5 points for each sample, with an accuracy of ±10HV.

[0092] 5. Coating bonding strength test: A scratch tester (refer to ISO26443 standard) was used with a Rockwell C scale diamond indenter to apply a vertical load at a rate of 100 N / min until the coating peeled off. The critical load at which the coating peeled off was recorded to evaluate the bonding strength between the coating and the pipe body, with an accuracy of ±1 MPa.

[0093] 6. Process Parameter Monitoring: Temperature sensors, pressure sensors, and speed sensors are installed in the melting, forming, and cooling processes to collect data such as furnace temperature, forming pressure, upper mold moving speed, and cooling air velocity in real time. The data collection frequency is 1 time / second to ensure the accuracy of process parameters.

[0094] In summary, each of the five embodiments has its own advantages and disadvantages. By adjusting the raw material ratio and process parameters, high borosilicate glass tubes with different performance can be prepared for different application scenarios, providing technical support for the diversified application of this product.

[0095] Please see Figure 1-7 This invention discloses a high borosilicate glass tube and its continuous hot-pressing process. Traditional high borosilicate glass, limited by its silicon dioxide-boron trioxide basic network, has a thermal expansion coefficient that has long remained at 3.8-5.0 × 10⁻⁶. -6 The temperature is limited to ℃, and it lacks optical control capabilities. This technology introduces rare earth oxides such as lanthanum oxide and yttrium oxide with cerium oxide and nano-titanium carbide micro / nano materials to construct a ternary composite system, achieving a synergistic leap in thermal, optical, and mechanical properties. Example 1 uses an extremely low addition of 0.1% lanthanum oxide + 0.1% yttrium oxide to reduce the coefficient of thermal expansion to 3.3 × 10⁻⁶. -6 / ℃, which is 13% lower than traditional glass. At the same time, 0.05% cerium oxide eliminates 90% of micron-sized bubbles, and the light transmittance is increased from 85% to 88%. This is the first time that the compatibility of rare earth-micro-nano system with traditional formulation has been verified.

[0096] Example 2 further increased the rare earth concentration to 1.5% lanthanum oxide and 1% yttrium oxide, resulting in a sharp decrease in the coefficient of thermal expansion to 2.5 × 10⁻⁶. -6 / ℃, breaking through the lowest value of existing technologies, and exhibiting no cracks after 200 cycles at -40℃ to 250℃, doubling its thermal shock resistance. The broadband absorption characteristics of rare earth ions enable an 8-14μm infrared shielding rate of 60%. Combined with deep clarification of 0.3% cerium oxide and dispersion strengthening of 0.1% nano-titanium carbide, the hardness of the glass matrix is ​​increased to 620HV. Combined with the zirconium diboride coating on the outer wall (hardness 2000HV), a dual protection system of "matrix strengthening + surface hardening" is constructed, improving wear resistance by more than 5 times. Compared with existing technologies that rely on coating to achieve optical functions, this solution achieves full-band control of ultraviolet-infrared through intrinsic material modification. The coating bonding strength reaches 65MPa, which is 62.5% higher than traditional coating processes, solving the industry problem of easy coating peeling.

[0097] II. A Dual Leap Forward in Extreme Environmental Performance and Process Efficiency: System Optimization from Materials to Processes

[0098] Addressing the lifespan bottleneck of traditional glass in high-temperature and highly corrosive environments, this technology upgrades the rare-earth stabilizing network structure and coating technology to achieve long-term service life in extreme environments. Example 5 uses 1.2% lanthanum oxide and 0.8% yttrium oxide to construct a high-temperature stabilizing network, raising the glass softening point from 820℃ to 950℃. It can withstand instantaneous high-temperature shocks of 1200℃ and more than 50 water-cooling cycles at 1000℃, representing a 60% improvement over existing technologies. Simultaneously, the zirconium diboride coating exhibits a bonding strength of 64MPa and a surface hardness of 2090HV, with a corrosion rate of <0.01μm / h in hydrofluoric acid vapor, a 90% reduction compared to traditional glass. This extends product lifespan from <3 months to >12 months, meeting the demands of extreme scenarios such as the nuclear industry and aerospace.

[0099] At the process level, continuous hot pressing molding achieves a balance between high precision and high efficiency through dynamic matching of pressure, speed, and temperature. Example 3, using 1.0 MPa pressure, a die speed of 1.0 mm / s, and a die temperature of 900℃, controls the outer diameter deviation to ±0.03 mm (compared to ±0.3 mm in existing technology), increasing production capacity to 12 m³ / h (compared to 8 m³ / h in traditional processes). Simultaneously, the boron nitride-silicon carbide composite lining extends furnace life from 6 months to 18 months, reduces maintenance costs by 66%, and reduces energy consumption by 15%. Example 4, through component simplification (total rare earth micro-nano content of 0.6%) and process fine-tuning, achieves ultra-high precision molding of ±0.02 mm, with a yield rate of 98%, a 13% improvement over traditional processes, and a 15% reduction in production costs. This is suitable for large-scale industrial pipe production, promoting the replacement of domestically produced equipment.

[0100] III. Systematic Innovation and Industrial Value of Technical Solutions: From Theoretical Breakthroughs to Practical Applications

[0101] The core innovation of this technology lies in the non-obvious innovation of the composition system and process. Rare earth ions (La) 3+ Y 3+ By filling network gaps and forming strong bonded coordination structures, it creates a synergistic effect with the clarifying and strengthening effects of micro / nano materials (TiC, CeO2), rather than simply adding up performance. For example, 0.02%-0.1% nano-titanium carbide forms a nanoscale reinforcing skeleton in the matrix, improving wear resistance by 8 times, breaking through the conventional understanding of those skilled in the art that "high content is required for micro / nano materials to be effective"; cerium oxide simultaneously achieves the dual functions of clarification and ultraviolet absorption, demonstrating cross-dimensional thinking in composition design.

[0102] At the industrial application level, this technology has constructed a product matrix of "basic-functional-customized" products, covering all scenarios from laboratory glassware to high-end aerospace equipment. The infrared shielding glasses in Examples 2 and 5 fill the gap in domestic high-end optical glass, with costs only 60%-70% of imported products. The cost-effective solutions in Examples 3 and 4 are suitable for mainstream industrial markets, and their increased production capacity and reduced energy consumption align with the trend of green manufacturing. Furthermore, technological breakthroughs such as the supersonic plasma spraying-chemical vapor deposition combined process and the boron nitride-silicon carbide composite liner are not only applicable to high borosilicate glass but can also be extended to other specialty glass systems, providing the industry with a universally applicable innovative methodology.

[0103] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific technical solutions or characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A high borosilicate glass tube, characterized by, The pipe body comprises raw materials including, by weight percentage, boron trioxide 18%-19%, alumina 3%-4.5%, zinc oxide 2%-4%, sodium oxide 1%-2%, potassium oxide 0.5%-1.5%, gallium oxide 0.5%-2%, lanthanum oxide 0.1%-1.5%, yttrium oxide 0.1%-1%, and further comprising 0.05%-0.3% cerium oxide and 0.02%-0.1% nano titanium carbide in the raw materials of the pipe body, with the balance being silicon dioxide; the wall thickness of the pipe body is 0.8-2.0 mm, and the outer diameter is 10-50 mm.

2. The high borosilicate glass tube according to claim 1, wherein The outer wall of the pipe body is compounded with a zirconium diboride ceramic coating with a thickness of 8-20 μm, which is prepared by plasma chemical vapor deposition, the bonding strength of the coating to the pipe body is ≥60 MPa, and the surface hardness is ≥2000 HV.

3. A continuous hot press forming process of high borosilicate glass tube, characterized in that, A process for preparing the high borosilicate glass pipe of any one of claims 1-2, the process comprising the following steps: S1, raw material preparation: mixing silica, boron trioxide, alumina, zinc oxide, sodium oxide, potassium oxide, gallium oxide, lanthanum oxide, yttrium oxide in proportion, adding cerium oxide and nano titanium carbide to obtain a mixture; S2, melting: putting the mixture into a melting furnace, melting at 1550-1650 ℃ to obtain a glass liquid, the inner lining of the melting furnace is made of boron nitride-silicon carbide composite refractory material, the content of boron nitride in the refractory material is 20%-30%, and the content of silicon carbide is 70%-80%; S3, continuous hot pressing forming: the glass liquid is conveyed into a forming mold through a flow channel, the forming mold comprises an upper mold and a lower mold, and a forming cavity with a diameter matching the outer diameter of the high borosilicate glass pipe is formed between the upper mold and the lower mold; during the forming process, the upper mold moves downward at a speed of 0.6-1.4 mm / s, a pressure of 0.6-1.4 MPa is applied to the glass liquid, and the temperature of the forming mold is controlled at 820-980 ℃ by a heating device, so that the glass liquid is formed into a glass pipe blank in the forming cavity; the inner wall of the flow channel is provided with a zirconium diboride ceramic coating with a thickness of 0.3-0.7 mm; S4, cooling and shaping: the formed glass pipe blank moves with the forming mold to a cooling area, and a cooling fan blows cold air with a temperature of 15-35 ℃ and a wind speed of 7-12 m / s to the glass pipe blank, so that the glass pipe blank is cooled to room temperature at a speed of 6-14 ℃ / min; S5, cutting: the cooled and shaped glass pipe blank is cut according to the predetermined length to obtain the high borosilicate glass pipe.

4. The continuous hot press forming process according to claim 3, characterized in that, The boron nitride-silicon carbide composite refractory material in step S2 is formed by isostatic pressing, with a density ≥ 2.8 g / cm 3 The erosion rate of the high boron-silicon glass liquid at 1600°C is ≤ 0.05 mm / h.

5. The continuous hot press forming process according to claim 3, characterized in that, The zirconium diboride ceramic coating in step S3 is prepared by supersonic plasma spraying, the content of ZrB2 phase in the coating is ≥95%, the porosity is ≤2%, and the thermal shock resistance under 1000 ℃ water cooling cycle is ≥50 times.

6. The continuous hot press forming process according to claim 3, characterized in that, The conveying roller in step S4 is made of graphite-carbon fiber composite material, and the surface is treated by polytetrafluoroethylene impregnation, and the friction coefficient is ≤0.

15.

7. The continuous hot press forming process according to claim 3, characterized in that, The cutting device in step S5 adopts a diamond wire saw and a laser combined cutting device, the wire saw feeding speed is 15-25 mm / s, the laser preheating temperature is 300-500 DEG C, and the end face parallelism is less than or equal to 0.05 mm.

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