Low-hydroxy quartz glass vacuum sintering method and apparatus therefor

Abstract

The application provides a low-hydroxyl quartz glass vacuum sintering method and equipment. The low-hydroxyl quartz glass vacuum sintering method comprises the following steps: placing quartz raw materials into a sintering furnace, and vacuumizing the sintering furnace until the pressure in the sintering furnace is at a first pressure; performing a hydroxyl removal pretreatment on the quartz raw materials; performing a deep hydroxyl removal treatment on the quartz raw materials after the hydroxyl removal pretreatment, and detecting whether the water molecule concentration in the gas environment in the sintering furnace is lower than a preset value in real time, and when the water molecule concentration is lower than the preset value, rapidly heating the sintering furnace; and performing a sintering treatment on the quartz raw materials.

Description

Technical Field

[0001] This application relates to the field of quartz sintering technology, and in particular to a vacuum sintering method and equipment for low-hydroxyl quartz glass. Background Technology

[0002] Quartz glass formed by sintering quartz blanks can be used in optical systems. However, when the hydroxyl content in quartz glass is high, it will affect the optical transmittance of quartz glass in the infrared band, making it unsuitable for some infrared optical systems. In addition, a high hydroxyl content in quartz glass will exacerbate the crystallization (devitrification) phenomenon of quartz glass, affecting the lifespan of quartz glass. Summary of the Invention

[0003] This application provides a vacuum sintering method and equipment for low-hydroxyl quartz glass to solve the problem that the high hydroxyl content of quartz glass affects its service life and application range in known technologies.

[0004] This application provides a vacuum sintering method for low-hydroxyl quartz glass, comprising the following steps: placing quartz raw material into a sintering furnace and evacuating the sintering furnace until the pressure inside the sintering furnace reaches a first pressure; performing a dehydroxylation pretreatment on the quartz raw material; performing a deep dehydroxylation treatment on the quartz raw material after the dehydroxylation pretreatment; real-time monitoring of whether the water molecule concentration in the gas environment inside the sintering furnace is lower than a preset value; and rapidly heating the sintering furnace when it is lower than the preset value; and performing a sintering treatment on the quartz raw material.

[0005] In one possible implementation, the dehydroxylation pretreatment includes the following steps: The sintering furnace is heated to a first temperature at a first heating rate; The sintering furnace is kept warm immediately.

[0006] In one possible implementation, the first heating rate is 5 to 10 °C / min, the first temperature is 500 to 700 °C, and the first time is 4 to 6 h.

[0007] In one possible implementation, when the quartz raw material undergoes the deep dehydroxylation treatment, the sintering furnace is heated to a second temperature at a second heating rate and maintained at the second temperature until the water molecule concentration in the gas environment inside the sintering furnace is lower than the preset value.

[0008] In one possible implementation, the second heating rate is 0.3 to 1 °C / min, the second temperature is 1000 to 1200 °C, and the preset value is 0.1 ppm.

[0009] In one possible implementation, when the water molecule concentration in the gas environment inside the sintering furnace is below 0.1 ppm, the sintering furnace is heated to a third temperature at a third heating rate and held at that temperature for a third time.

[0010] In one possible implementation, the third heating rate is 3 to 5 °C / min, the third temperature is 1300 to 1400 °C, and the third time is 1 to 2 h.

[0011] In one possible implementation, the sintering process of the quartz raw material includes the following steps: The sintering furnace is heated to a fourth temperature at a fourth heating rate and held at that temperature for a fourth time. The fourth heating rate is 2 to 3 °C / min, the fourth temperature is 1450 to 1550 °C, and the fourth time is 1 to 3 h. The sintering furnace is heated to a fifth temperature at a fifth heating rate and held at that temperature for a fifth time. The fifth heating rate is 1 to 2 °C / min, the fifth temperature is 1600 to 1650 °C, and the fifth time is 5 to 8 h.

[0012] In one possible implementation, after the sintering treatment of the quartz raw material is completed, the following steps are further included: The sintering furnace is rapidly cooled until the temperature inside the sintering furnace drops below 800°C; The sintering furnace is slowly cooled until the temperature inside the sintering furnace drops below 100°C.

[0013] This application also provides a vacuum sintering apparatus for low-hydroxyl quartz glass, applied to the above-mentioned vacuum sintering method for low-hydroxyl quartz glass, wherein the low-hydroxyl quartz glass vacuum sintering apparatus comprises: Sintering furnace; A vacuum assembly configured to evacuate the sintering furnace; A gas analysis component is provided on the pipeline between the vacuum assembly and the sintering furnace, and the gas analysis component is configured to detect the concentration of water molecules in the gas extracted from the sintering furnace.

[0014] The vacuum sintering method for low-hydroxyl quartz glass disclosed in this application monitors the concentration of water molecules in the gas environment of the sintering furnace in real time during the deep dehydroxylation treatment of the quartz raw material. The deep dehydroxylation treatment is only terminated and the next step is performed once the concentration falls below the preset value. This ensures that the sintered quartz glass has a low hydroxyl content, preventing high hydroxyl content from affecting the quality and service life of the quartz glass. Furthermore, by performing a dehydroxylation pretreatment on the quartz raw material before the deep dehydroxylation treatment, physically adsorbed moisture in the quartz glass can be removed first. This prevents water vapor from rapidly escaping during the deep dehydroxylation treatment, which could cause cracking of the quartz raw material and affect the quality of the formed quartz glass. After the deep dehydroxylation treatment of the quartz raw material is completed, the sintering furnace is rapidly heated before sintering, creating a transition phase between the deep dehydroxylation and sintering processes. This rapid heating allows the quartz raw material to pass through the crystallization danger zone, further ensuring the quality of the formed quartz glass. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the low-hydroxyl quartz glass vacuum sintering equipment of this application in one embodiment.

[0016] Figure 2 This is a schematic diagram of the structure of the low-hydroxyl quartz glass vacuum sintering equipment of this application after being loaded with quartz raw materials in one embodiment.

[0017] Figure 3 This is a schematic diagram of the water molecule content detection process in one embodiment of the vacuum sintering method for low-hydroxyl quartz glass of this application.

[0018] Figure 4 This is a schematic flowchart of the vacuum sintering method for low-hydroxyl quartz glass according to this application in one embodiment.

[0019] Key component symbols: 100, Low-hydroxyl quartz glass vacuum sintering equipment; 200, Low-hydroxyl quartz glass vacuum sintering method; 10, Sintering furnace; 11, First furnace body; 12, Second furnace body; 13, Furnace cover plate; 14, Graphite cover plate; 20, Drive assembly; 21, Rotary motor; 22, Water-cooled guide rod; 23, Magnetorheological fluid; 24, Graphite lifting rod; 25, Weighing sensor; 30, Air intake assembly; 31, Air supply device; 32, First pipeline. 33. First pneumatic valve; 34. Second pipeline; 35. Third pipeline; 36. Second pneumatic valve; 40. Temperature measuring component; 41. Infrared temperature measuring device; 50. Vacuum pumping component; 51. Fourth pipeline; 510. First exhaust nozzle; 52. Fifth pipeline; 520. Second exhaust nozzle; 53. Third pneumatic valve; 54. Fourth pneumatic valve; 55. Sixth pipeline; 56. Fifth pneumatic valve; 57. Vacuum pump set; 60. Gas analysis component.

[0020] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0021] The following description will refer to the accompanying drawings to provide a more complete picture of the present application. The drawings illustrate exemplary embodiments of the present application. However, the present application may be implemented in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. These exemplary embodiments are provided to make the present application thorough and complete, and to fully convey the scope of the present application to those skilled in the art. The same reference numerals denote the same or similar components.

[0022] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to limit the application. As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” are intended to also include the plural forms. Furthermore, when used herein, “comprising” and / or “including” and / or “having,” integers, steps, operations, components, and / or components, but does not exclude the presence or addition of one or more other features, regions, integers, steps, operations, components, and / or groups thereof.

[0023] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Furthermore, unless expressly defined herein, terms such as those defined in a general dictionary should be interpreted as having the same meaning as they have in the relevant art and in the content of this application, and will not be interpreted as having an idealized or overly formal meaning.

[0024] The specific embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0025] like Figures 1 to 4 As shown, this embodiment provides a low-hydroxyl quartz glass vacuum sintering equipment 100, which is applied to the low-hydroxyl quartz glass vacuum sintering method 200. The low-hydroxyl quartz glass vacuum sintering equipment 100 includes a sintering furnace 10, a vacuum pumping component 50, and a gas analysis component 60.

[0026] Quartz raw materials can be placed in sintering furnace 10 for dehydroxylation and sintering treatment. Vacuum pumping component 50 is configured to evacuate sintering furnace 10. Gas analysis component 60 is located on the pipeline between vacuum pumping component 50 and sintering furnace 10. Gas analysis component 60 is configured to detect the concentration of water molecules in the gas extracted from sintering furnace 10.

[0027] Thus, when performing dehydroxylation treatment on quartz raw materials, the concentration of water molecules in the air inside the sintering furnace 10 is monitored in real time to determine whether the quartz raw materials in the current state need to continue dehydroxylation treatment. If the concentration is higher than the preset standard, the dehydroxylation treatment continues. If the concentration is at or below the preset standard, the dehydroxylation treatment can be completed and the next processing step can be carried out.

[0028] Please combine Figure 1 and Figure 2 In one embodiment, the sintering furnace 10 includes a first furnace body 11 and a second furnace body 12. The first furnace body 11 is a cylindrical structure with open ends and a hollow interior, and the second furnace body 12 is a cylindrical structure with open end and a hollow interior. The second furnace body 12 is connected to the bottom end of the first furnace body 11 and communicates with the first furnace body 11, so that the quartz raw material can first enter the first furnace body 11 from outside the sintering furnace 10, and then enter the second furnace body 12 from the first furnace body 11. The outer diameter of the second furnace body 12 is larger than the outer diameter of the first furnace body 11. The first furnace body 11 can serve as a muffle furnace, and the first furnace body 11 is provided with an observation window to facilitate observation of the quartz raw material inside the first furnace body 11 from outside the first furnace body 11.

[0029] In addition, the sintering furnace 10 also includes a furnace body cover plate 13 and a graphite cover plate 14. The furnace body cover plate 13 has a circular structure and can be installed on the opening at the top of the first furnace body 11. The graphite cover plate 14 has a circular structure and can be installed on the opening at the end of the second furnace body 12 near the first furnace body 11.

[0030] In this embodiment, the low-hydroxyl quartz glass vacuum sintering equipment 100 further includes a drive assembly 20, which includes a rotary motor 21, a water-cooled guide rod 22, a magnetic fluid 23, and a graphite suspension rod 24.

[0031] A rotary motor 21 is connected to one end of the water-cooled guide rod 22 to drive the water-cooled guide rod 22 to rotate. A weighing sensor 25 is provided between the rotary motor 21 and the water-cooled guide rod 22. The water-cooled guide rod 22 passes through the furnace cover plate 13 and the graphite cover plate 14. A magnetic fluid 23 is provided between the furnace cover plate 13 and the water-cooled guide rod 22. A graphite hanging rod 24 is provided between the graphite cover plate 14 and the water-cooled guide rod 22. The graphite hanging rod 24 is a hollow cylindrical structure. Quartz raw material is installed on the graphite hanging rod 24 through graphite pins. The graphite hanging rod 24 can rotate with the water-cooled guide rod 22 to realize the rotation of the quartz raw material.

[0032] In addition, a weighing sensor 25 is provided at the upper end of the water-cooled guide rod 22, which can provide real-time feedback on the weight of the quartz raw material inside the furnace body, so as to prevent the equipment from continuing to produce and consuming power after abnormal rod drop.

[0033] In addition, the rotary motor 21 is connected to a lifting mechanism (not shown) to drive the rotary motor 21 to lift and lower, thereby realizing the lifting and lowering of the quartz raw material.

[0034] Please combine Figure 1 and Figure 2 In one embodiment, the low-hydroxyl quartz glass vacuum sintering equipment 100 further includes an air inlet assembly 30. The air inlet assembly 30 includes an air supply device 31, a first pipe 32, a second pipe 34, a third pipe 35, a first pneumatic valve 33, and a second pneumatic valve 36.

[0035] One end of the first pipe 32 is connected to the first furnace body 11, and the other end is connected to the gas supply device 31 to supply gas to the first furnace body 11 through the gas supply device 31. The first pneumatic valve 33 is located on the pipe of the first pipe 32.

[0036] The low-hydroxyl quartz glass vacuum sintering equipment 100 also includes a temperature measuring component 40, which includes multiple infrared temperature measuring devices 41 located on the same side of the second furnace body 12. The multiple infrared temperature measuring devices 41 are arranged sequentially and at intervals along the height direction of the second furnace body 12. By arranging multiple infrared temperature measuring devices 41 along the height direction of the second furnace body 12, various regions along the height direction of the quartz raw material can be detected, thus improving the accuracy of quartz raw material detection.

[0037] In this embodiment, the number of infrared temperature measuring devices 41 is set to four. It is understood that in other embodiments, the number of infrared temperature measuring devices 41 may also be set to five or other numbers, and the specific number can be selected according to actual needs.

[0038] One end of the second pipe 34 is connected to the first pipe 32, and one end of the third pipe 35 is connected to the second furnace body 12. The infrared temperature measuring device 41 adopts an elongated pipe and is purged with air through the second pipe 34, so that the air supply component can simultaneously blow air to the glass windows of multiple infrared temperature measuring devices 41, avoiding long-term accumulation of powder and dust that would cause contamination of the observation windows, effectively reducing the adhesion of impurities to each infrared temperature measuring device 41, avoiding measurement accuracy deviation, and improving the accuracy of temperature measurement. This allows the control system to combine the power controller and temperature controller with more accurate temperature measurement data to achieve precise step-by-step temperature control of the sintering furnace 10, thereby improving the dehydroxylation quality and sintering quality of the quartz raw material.

[0039] The first pneumatic valve 33 is located on the pipeline between the connection between the second pipeline 34 and the first pipeline 32 and the air supply device 31, and the second pneumatic valve 36 is located on the pipeline of the third pipeline 35.

[0040] Please combine Figure 1 and Figure 2 In one embodiment, the vacuum assembly 50 includes a fourth pipe 51, a fifth pipe 52, a sixth pipe 55, a third pneumatic valve 53, a fourth pneumatic valve 54, a fifth pneumatic valve 56, and a vacuum pump assembly 57.

[0041] Vacuum pump assembly 57 includes mechanical pumps and Roots pumps, etc. A first exhaust nozzle 510 is provided at one end of the fourth pipe 51, extending from the side wall of the second furnace body 12 into the second furnace body 12, allowing gas inside the second furnace body 12 to be discharged through the first exhaust nozzle 510. A second exhaust nozzle 520 is provided at one end of the fifth pipe 52, extending from the side wall of the second furnace body 12 into the second furnace body 12, allowing gas inside the second furnace body 12 to be discharged through the second exhaust nozzle 520. Along the height direction of the second furnace body 12, the first exhaust nozzle 510 and the second exhaust nozzle 520 are spaced apart, with the first exhaust nozzle 510 positioned near the top of the second furnace body 12 and the second exhaust nozzle 520 positioned near the bottom of the second furnace body 12. This improves the efficiency and completeness of gas discharge from the second furnace body 12, ensuring the accuracy of sampling and detection by the subsequent gas analysis component 60 and improving the precise control of quartz raw material dehydroxylation.

[0042] Both the first exhaust nozzle 510 and the second exhaust nozzle 520 are inclined. The first exhaust nozzle 510 is inclined downward and the second exhaust nozzle 520 is inclined upward. The inclination angle of the first exhaust nozzle 510 and the second exhaust nozzle 520 is approximately 45°, so that a flow guide slope with an inclination angle of 45° is formed at the first exhaust nozzle 510 and the second exhaust nozzle 520, and the molybdenum alloy arc-shaped flow guide plate guides the flow of hydroxyl gas.

[0043] The fourth pipe 51, the fifth pipe 52, and the sixth pipe 55 are all made of stainless steel with polished inner walls (roughness Ra≤0.8μm) to reduce gas retention and improve monitoring accuracy. The fourth pipe 51 is equipped with a third pneumatic valve 53, the fifth pipe 52 is equipped with a fourth pneumatic valve 54, and the sixth pipe 55 is equipped with a fifth pneumatic valve 56.

[0044] One end of the sixth pipe 55 is connected to the end of the fourth pipe 51 and the fifth pipe 52 away from the second furnace body 12. The vacuum pump group 57 and the gas analysis component 60 are both located on the sixth pipe 55 so that the gas in the second furnace body 12 can be drawn into the gas analysis component 60 through the vacuum pump group 57.

[0045] In this embodiment, the gas analysis component 60 employs an infrared gas analyzer, combined with... Figure 3 The diagram shows the workflow of an infrared gas analyzer.

[0046] After the second furnace body 12 releases water vapor after dehydroxylation, it is drawn into the vacuum pump group 57. At this time, the gas ballast device is turned on to release water vapor to prevent the water vapor in the gas extracted from the second furnace body 12 from condensing and to heat the sampling probe of the infrared gas analyzer. All pipelines through which the water vapor is extracted are heated to keep the water vapor in a gaseous state, for example, it can be maintained at 150°C. The extracted water vapor is filtered and dust removed by a high-temperature filter before flowing to the infrared gas analyzer, which then accurately measures the H2O content in the gas.

[0047] like Figure 4 As shown, and in combination Figure 2 This embodiment also provides a vacuum sintering method 200 for low-hydroxyl quartz glass, comprising the following steps: S1. Place the quartz raw material into the sintering furnace 10 and evacuate the sintering furnace 10 until the pressure inside the sintering furnace 10 reaches the first pressure. S2. Perform dehydroxylation pretreatment on quartz raw materials; S3. Perform deep dehydroxylation treatment on the quartz raw material that has completed the dehydroxylation pretreatment, and detect in real time whether the water molecule concentration in the gas environment inside the sintering furnace 10 is lower than the preset value. If it is lower than the preset value, rapidly heat up the sintering furnace 10. S4. Sinter the quartz raw material.

[0048] Step S1 specifically includes the following steps performed in sequence: S11, raw material preparation; S12, initial vacuuming; S13, secondary vacuuming; S14, raw material confirmation.

[0049] For step S11, high-purity quartz raw material (e.g., silica concentration greater than 99.99%) is provided. The quartz raw material has dimensions of D450×2000mm. The quartz raw material is installed on the graphite suspension rod 24 using graphite pins. The water-cooled guide rod 22 and the furnace cover plate 13 are lowered to position the quartz raw material within the area of ​​the first furnace body 11. The furnace cover plate 13 is then closed to seal the opening at the top of the first furnace body 11. The sealing properties of the magnetic fluid 23 create a sealed environment for the first furnace body 11 and the second furnace body 12 connected to it. During this process, the weight of the quartz raw material is monitored in real time using a weighing sensor 25.

[0050] For step S12, in order to ensure that the quartz raw material is broken by directly drawing a vacuum from atmospheric pressure at the first exhaust nozzle 510, the mechanical pump in the vacuum pump group 57 is first started, and the fourth pneumatic valve 54 and the fifth pneumatic valve 56 are opened to draw the vacuum degree in the entire sintering furnace 10 from atmospheric pressure to 10000Pa. Then the fifth pneumatic valve 56 is closed and the third pneumatic valve 53 is opened.

[0051] For step S13, when the vacuum level inside the entire sintering furnace 10 reaches the allowable starting pressure of the Roots pump, the Roots pump automatically starts and continues to evacuate the sintering furnace 10 until the pressure inside the furnace drops to 8 Pa.

[0052] For step S14, after confirming through the observation window of the first furnace body 11 that the quartz raw material is in normal condition, the water-cooled guide rod 22 automatically descends to send the quartz raw material into the second furnace body 12. When the graphite cover plate 14 is in place and the second furnace body 12 is closed, the rotary motor 21 is started, which in turn drives the quartz raw material to rotate through the water-cooled guide rod 22. The rotation speed of the quartz raw material is 1 to 5 r / min.

[0053] In this embodiment, the rotation speed of the quartz raw material can be 1 r / min, 2 r / min, 3 r / min, 4 r / min, 5 r / min, etc., but is not limited to the values ​​listed above. Other values ​​not listed in this range are also within the protection scope of this application.

[0054] For step S2, the dehydroxylation pretreatment includes the following steps: S21. Heat the sintering furnace 10 to the first temperature at the first heating rate; S22, sintering furnace 10 heat preservation first time.

[0055] In this embodiment, the quartz raw material undergoes a dehydroxylation pretreatment to prevent rapid steam escape that could cause cracking. A slow heating method is used to remove physically adsorbed moisture from the quartz raw material. The first heating rate is 5 to 10 °C / min, the first temperature is 500 to 700 °C, and the first time is 4 to 6 hours.

[0056] In this embodiment, the first heating rate can be 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, etc., but is not limited to the values ​​listed above. Other values ​​not listed in this range are also within the protection scope of this application.

[0057] In this embodiment, the first temperature can specifically be 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, 610℃, 620℃, 630℃, 640℃, 650℃, 660℃, 670℃, 680℃, 690℃, 700℃, etc., but is not limited to the values ​​listed above. Other values ​​not listed within this range are also within the protection scope of this application.

[0058] In this embodiment, the first time can specifically be 4.0h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h, 5.0h, 5.1h, 5.2h, 5.3h, 5.4h, 5.5h, 5.6h, 5.7h, 5.8h, 5.9h, 6.0h, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the protection scope of this application.

[0059] For step S3, when the quartz raw material undergoes deep dehydroxylation treatment, the sintering furnace 10 is heated to a second temperature at a second heating rate and maintained at the second temperature until the water molecule concentration in the gas environment inside the sintering furnace 10 is lower than a preset value.

[0060] In this embodiment, during the deep dehydroxylation treatment of the quartz raw material, a slow heating rate lower than that of the dehydroxylation pretreatment ensures temperature equilibrium between the interior and surface of the quartz raw material. The thoroughness of dehydroxylation at this stage directly determines the hydroxyl content of the final product. Within this temperature range, the viscosity of the quartz glass has not yet significantly decreased, and interconnected open channels still exist internally. Hydroxyl groups (Si-OH) react: Si-OH + HO-Si → Si-O-Si + H2O↑. The generated water molecules can diffuse smoothly along the interconnected channels to the surface and are then removed by the vacuum pump unit 57.

[0061] In this embodiment, the second heating rate is 0.3 to 1°C / min, the second temperature is 1000 to 1200°C, and the preset value is 0.1 ppm.

[0062] In this embodiment, the second heating rate can be 0.3℃ / min, 0.4℃ / min, 0.5℃ / min, 0.6℃ / min, 0.7℃ / min, 0.8℃ / min, 0.9℃ / min, 1.0℃ / min, etc., but is not limited to the values ​​listed above. Other values ​​not listed in this range are also within the protection scope of this application.

[0063] In this embodiment, the second temperature can specifically be 1000℃, 1010℃, 1020℃, 1030℃, 1040℃, 1050℃, 1060℃, 1070℃, 1080℃, 1090℃, 1100℃, 1110℃, 1120℃, 1130℃, 1140℃, 1150℃, 1160℃, 1170℃, 1180℃, 1190℃, 1200℃, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the protection scope of this application.

[0064] In this embodiment, when the water molecule concentration in the gas environment inside the sintering furnace 10 is below 0.1 ppm, the sintering furnace 10 is heated to a third temperature at a third heating rate and held at that temperature for a third time. This stage serves as a transitional stage, preventing the precipitation of quartz crystals and using a rapid heating method to pass through the dangerous crystallization zone of quartz glass.

[0065] The third heating rate is 3 to 5 °C / min, the third temperature is 1300 to 1400 °C, and the third time is 1 to 2 h.

[0066] In this embodiment, the third heating rate can specifically be 3.0℃ / min, 3.1℃ / min, 3.2℃ / min, 3.3℃ / min, 3.4℃ / min, 3.5℃ / min, 3.6℃ / min, 3.7℃ / min, 3.8℃ / min, 3.9℃ / min, 4.0℃ / min, 4.1℃ / min, 4.2℃ / min, 4.3℃ / min, 4.4℃ / min, 4.5℃ / min, 4.6℃ / min, 4.7℃ / min, 4.8℃ / min, 4.9℃ / min, 5.0℃ / min, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the protection scope of this application.

[0067] In this embodiment, the third temperature may specifically be 1300℃, 1310℃, 1320℃, 1330℃, 1340℃, 1350℃, 1360℃, 1370℃, 1380℃, 1390℃, 1400℃, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the protection scope of this application.

[0068] In this embodiment, the third time can specifically be 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2.0h, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the protection scope of this application.

[0069] In step S4, the viscosity of the quartz raw material decreases sharply under high temperature and viscous flow occurs under the drive of surface tension. The pores on the quartz raw material are quickly sealed, thus forming isolated closed pores. The closed pores gradually shrink until they are eliminated, and finally the quartz raw material is completely densified and transparent to form quartz glass.

[0070] The sintering process for quartz raw materials includes the following steps: S41. The sintering furnace 10 is heated to the fourth temperature at the fourth heating rate and held at the fourth temperature for the fourth time. The fourth heating rate is 2 to 3℃ / min, the fourth temperature is 1450 to 1550℃, and the fourth time is 1 to 3h. S42. Heat the sintering furnace 10 to the fifth temperature at the fifth heating rate and hold it at the fifth temperature for the fifth time. The fifth heating rate is 1 to 2℃ / min, the fifth temperature is 1600 to 1650℃, and the fifth time is 5 to 8h.

[0071] In this embodiment, the fourth heating rate can specifically be 2.0℃ / min, 2.1℃ / min, 2.2℃ / min, 2.3℃ / min, 2.4℃ / min, 2.5℃ / min, 2.6℃ / min, 2.7℃ / min, 2.8℃ / min, 2.9℃ / min, 3.0℃ / min, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the protection scope of this application.

[0072] In this embodiment, the fourth temperature may specifically be 1450℃, 1460℃, 1470℃, 1480℃, 1490℃, 1500℃, 1510℃, 1520℃, 1530℃, 1540℃, 1550℃, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the protection scope of this application.

[0073] In this embodiment, the fourth time can specifically be 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2.0h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h, 3.0h, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the protection scope of this application.

[0074] In this embodiment, the fifth heating rate can specifically be 1.0℃ / min, 1.1℃ / min, 1.2℃ / min, 1.3℃ / min, 1.4℃ / min, 1.5℃ / min, 1.6℃ / min, 1.7℃ / min, 1.8℃ / min, 1.9℃ / min, 2.0℃ / min, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the protection scope of this application.

[0075] In this embodiment, the fifth temperature can be 1600℃, 1610℃, 1620℃, 1630℃, 1640℃, 1650℃, etc., but is not limited to the values ​​listed above. Other values ​​not listed in this range are also within the protection scope of this application.

[0076] In this embodiment, the fifth time can specifically be 5.0h, 5.1h, 5.2h, 5.3h, 5.4h, 5.5h, 5.6h, 5.7h, 5.8h, 5.9h, 6.0h, 6.1h, 6.2h, 6.3h, 6.4h, 6.5h, 6.6h, 6.7h, 6.8h, 6.9h, 7.0h, 7.1h, 7.2h, 7.3h, 7.4h, 7.5h, 7.6h, 7.7h, 7.8h, 7.9h, 8.0h, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the protection scope of this application.

[0077] In this embodiment, after the quartz raw material has undergone sintering, step S5 is further included, which specifically includes the following steps: S51. Rapidly cool the sintering furnace 10 until the temperature inside the sintering furnace 10 drops below 800°C; S52. Slowly cool the sintering furnace 10 until the temperature inside the sintering furnace 10 drops below 100°C.

[0078] After the high-temperature densification stage, the third pneumatic valve 53 and the fourth pneumatic valve 54 are closed to allow the sintered quartz glass to cool rapidly and pass through the crystallization zone again, thereby inhibiting crystal growth. Then, the first pneumatic valve 33 and the second pneumatic valve 36 are opened, and nitrogen (N2) is injected into the entire sintering furnace 10 through the gas supply device 31 at a flow rate of 80 L / min. The nitrogen can also be diverted to the tube wall of the infrared thermometer 41 to purge the tube wall, thereby dispersing the dust accumulated on the infrared thermometer 41, facilitating the processing of the next quartz raw material.

[0079] When the temperature inside the sintering furnace 10 drops below the crystallization temperature (below 800℃), the cooling rate is reduced, i.e., the nitrogen flow rate is reduced to 40L / min, to reduce the internal thermal stress of the quartz glass and prevent it from cracking. Then, the second pneumatic valve 36 is closed. When the internal temperature of the sintering furnace 10 drops below 100℃, the furnace cover 13 is opened, the quartz glass is lifted to the first furnace body 11, and then removed from the first furnace body 11.

[0080] Example 1 Step 1: Provide the above-mentioned quartz raw material, the weight of which is 200kg, and place the quartz raw material into the first furnace body 11.

[0081] Step 2: Start the vacuum pump group 57, evacuate the sintering furnace 10 to a vacuum degree ≤ 8Pa, and then the quartz raw material enters the second furnace body 12 and rotates at a speed of 1r / min.

[0082] Step 3: Dehydroxylation pretreatment stage. The sintering furnace 10 is heated from room temperature to 600℃ at a heating rate of 10℃ / min to remove the physically adsorbed moisture in the quartz raw material, and then kept at this temperature for 6 hours.

[0083] Step 4: Deep dehydroxylation stage. The sintering furnace 10 is heated from 600℃ to 1100℃ at a heating rate of 1℃ / min and kept at a constant temperature until the H2O in the extracted gas is ≤0.1ppm as monitored by the infrared gas analyzer.

[0084] Step 5: Transition and connection stage, sintering furnace 10 heats from 1100℃ to 1380℃ at a heating rate of 5℃ / min, rapidly heating through the crystallization danger zone of quartz glass, and holding at that temperature for 2 hours.

[0085] Step 6: Low-temperature sintering stage, the sintering furnace 10 is heated from 1380℃ to 1500℃ at a heating rate of 3℃ / min and held at that temperature for 3 hours.

[0086] Step 7: High-temperature densification stage, sintering furnace 10 is heated from 1500℃ to 1620℃ at a heating rate of 2℃ / min and held at that temperature for 5 hours.

[0087] Step 8: Stop heating and close the third pneumatic valve 53 and the fourth pneumatic valve 54; Step 9: Introduce nitrogen gas at a temperature of 20°C and a flow rate of 80 L / min into the sintering furnace 10, rapidly cool it to below 800°C, adjust the nitrogen flow rate to 40 L / min, and slowly cool it to below 100°C to end production.

[0088] After testing, the hydroxyl content in the quartz glass was 1.5 ppm, with no bubbles, no streaks, and metallic impurities <100 ppb.

[0089] Example 2 The only difference between this and Example 1 is that the rotation rate in step 2 is adjusted to 3 r / min.

[0090] After testing, the hydroxyl content in the quartz glass was 1.4 ppm, with no bubbles, no streaks, and metallic impurities <100 ppb.

[0091] Example 3 The only difference between this and Example 1 is that the rotation rate in step 2 is adjusted to 5 r / min.

[0092] After testing, the hydroxyl content in the quartz glass was 1.5 ppm, with no bubbles, no streaks, and metallic impurities <100 ppb.

[0093] Example 4 The only difference between this and Example 1 is that the heating rate in step 3 is adjusted to 5°C / min.

[0094] After testing, the hydroxyl content in the quartz glass was 1.3 ppm, with no bubbles, no streaks, and metallic impurities <100 ppb.

[0095] Example 5 The only difference between this and Example 1 is that the heat preservation time in step 3 is adjusted to 4 hours.

[0096] After testing, the hydroxyl content in the quartz glass was 1.6 ppm, with no bubbles, no streaks, and metallic impurities <100 ppb.

[0097] Example 6 The only difference between this example and Example 1 is that the heating rate in step 4 is adjusted to 0.5℃ / min.

[0098] After testing, the quartz glass contained 0.2 ppm of hydroxyl groups, no bubbles, no streaks, and metallic impurities <100 ppb.

[0099] Example 7 The only difference between this example and Example 1 is that the heating rate in step 4 is adjusted to 0.3℃ / min.

[0100] After testing, the hydroxyl content in the quartz glass was found to be 0.6 ppm, with no bubbles, no streaks, and metallic impurities <100 ppb.

[0101] Example 8 The only difference between this and Example 1 is that the heating rate in step 5 is adjusted to 3°C / min.

[0102] After testing, the hydroxyl content in the quartz glass was 2.1 ppm, with no bubbles, no streaks, and metallic impurities <100 ppb.

[0103] Example 9 The only difference between this and Example 1 is that the heat preservation time in step 5 is adjusted to 1 hour.

[0104] After testing, the hydroxyl content in the quartz glass was 1.8 ppm, with no bubbles, no streaks, and metallic impurities <100 ppb.

[0105] Example 10 The only difference between this and Example 1 is that the heating rate in step 6 is adjusted to 2°C / min.

[0106] After testing, the hydroxyl content in the quartz glass was 1.5 ppm, with no bubbles, no streaks, and metallic impurities <100 ppb.

[0107] Example 11 The only difference between this and Example 1 is that the heat preservation time in step 6 is adjusted to 1 hour.

[0108] After testing, the hydroxyl content in the quartz glass was 1.5 ppm, with no bubbles, no streaks, and metallic impurities <100 ppb.

[0109] Example 12 The only difference between this and Example 1 is that the heating rate in step 7 is adjusted to 1°C / min.

[0110] After testing, the hydroxyl content in the quartz glass was 1.3 ppm, with no bubbles, no streaks, and metallic impurities <100 ppb.

[0111] Example 13 The only difference between this and Example 1 is that the heat preservation time in step 7 is adjusted to 8 hours.

[0112] After testing, the hydroxyl content in the quartz glass was 1.1 ppm, with no bubbles, no streaks, and metallic impurities <100 ppb.

[0113] Comparative Example 1 The only difference between it and Example 1 is that the sintering furnace 10 directly heats the temperature from room temperature to 1100°C at a heating rate of 5°C / min.

[0114] Tests revealed that the hydroxyl content in the quartz glass was 1.8 ppm, and streaks were present in the quartz glass.

[0115] Comparative Example 2 The only difference between it and Example 1 is that the sintering furnace 10 directly heats the temperature from room temperature to 1100°C at a heating rate of 1°C / min.

[0116] Tests revealed that the quartz glass contained 1.7 ppm of hydroxyl groups and had air bubbles, impurities, and streaks.

[0117] Comparative Example 3 The only difference between it and Example 1 is that no heat preservation treatment is performed in step 3.

[0118] Tests revealed that the quartz glass contained 1.8 ppm of hydroxyl groups and had air bubbles as impurities.

[0119] Comparative Example 4 The only difference between it and Example 1 is that step 5 is omitted, and the sintering furnace 10 is directly heated from 1100°C to 1500°C at a heating rate of 3°C / min.

[0120] Tests revealed that the quartz glass contained 1.6 ppm of hydroxyl groups, and that it contained air bubbles and impurities, as well as some areas lacking striations.

[0121] Comparative Example 5 The only difference between this and Example 1 is that the heating rate in step 3 is adjusted to 4°C / min.

[0122] Tests revealed that the quartz glass contained 1.8 ppm of hydroxyl groups, had air bubbles, and contained more than 100 ppb of metallic impurities.

[0123] Comparative Example 6 The only difference between this and Example 1 is that the heating rate in step 3 is adjusted to 11°C / min.

[0124] Tests showed that the hydroxyl content in the quartz glass was 1.2 ppm, and the quartz glass had streaks.

[0125] Comparative Example 7 The only difference between this and Example 1 is that in step 3, the sintering furnace 10 is heated to 800°C.

[0126] Tests showed that the hydroxyl content in the quartz glass was 1.0 ppm, and the quartz glass had streaks.

[0127] Comparative Example 8 The only difference between this example and Example 1 is that the heating rate in step 4 is adjusted to 0.2℃ / min.

[0128] Tests revealed that the quartz glass contained 2.5 ppm of hydroxyl groups and contained air bubbles, impurities, and streaks.

[0129] Comparative Example 9 The only difference between this and Example 1 is that the heating rate in step 4 is adjusted to 1.1℃ / min.

[0130] Tests revealed that the quartz glass contained 2.0 ppm of hydroxyl groups and contained bubbles, impurities, and streaks.

[0131] Comparative Example 10 The only difference between this and Example 1 is that in step 4, the sintering furnace 10 is heated to 1250°C.

[0132] After testing, the hydroxyl content in the quartz glass was 1.8 ppm, with no obvious bubble impurities, no obvious streaks, and metallic impurities <100 ppb, but not as good as in Example 1.

[0133] Comparative Example 11 The only difference between this and Example 1 is that the heating rate in step 5 is adjusted to 2°C / min.

[0134] Tests showed that the quartz glass contained 1.8 ppm of hydroxyl groups and had obvious streaks.

[0135] Comparative Example 12 The only difference between this and Example 1 is that the heating rate in step 5 is adjusted to 6°C / min.

[0136] Tests showed that the hydroxyl content in the quartz glass was 1.7 ppm, with no obvious bubbles or impurities, and no obvious streaks.

[0137] Comparative Example 13 The only difference between this and Example 1 is that in step 5, the sintering furnace 10 is heated to 1410°C.

[0138] Tests showed that the quartz glass contained 1.5 ppm of hydroxyl groups, with no obvious bubbles or impurities, and no obvious streaks.

[0139] The specific embodiments of this application have been described above with reference to the accompanying drawings. However, those skilled in the art will understand that various changes and substitutions can be made to the specific embodiments of this application without departing from the scope of this application. All such changes and substitutions fall within the scope defined by this application.

Claims

1. A vacuum sintering method for low-hydroxyl quartz glass, characterized in that, Includes the following steps: Quartz raw material is placed into a sintering furnace, and the sintering furnace is evacuated until the pressure inside the sintering furnace reaches the first pressure. The quartz raw material is subjected to a dehydroxylation pretreatment; The quartz raw material that has undergone the dehydroxylation pretreatment is subjected to deep dehydroxylation treatment. The concentration of water molecules in the gas environment inside the sintering furnace is detected in real time to see if it is lower than a preset value. If it is lower than the preset value, the sintering furnace is rapidly heated. The quartz raw material is subjected to sintering treatment.

2. The vacuum sintering method for low-hydroxyl quartz glass as described in claim 1, characterized in that, The dehydroxylation pretreatment includes the following steps: The sintering furnace is heated to a first temperature at a first heating rate; The sintering furnace is kept warm immediately.

3. The vacuum sintering method for low-hydroxyl quartz glass as described in claim 2, characterized in that, The first heating rate is 5 to 10 °C / min, the first temperature is 500 to 700 °C, and the first time is 4 to 6 h.

4. The vacuum sintering method for low-hydroxyl quartz glass as described in claim 1, characterized in that, When the quartz raw material undergoes the deep dehydroxylation treatment, the sintering furnace is heated to a second temperature at a second heating rate and maintained at the second temperature until the water molecule concentration in the gas environment inside the sintering furnace is lower than the preset value.

5. The vacuum sintering method for low-hydroxyl quartz glass as described in claim 4, characterized in that, The second heating rate is 0.3 to 1 °C / min, the second temperature is 1000 to 1200 °C, and the preset value is 0.1 ppm.

6. The vacuum sintering method for low-hydroxyl quartz glass as described in claim 5, characterized in that, When the water molecule concentration in the gas environment inside the sintering furnace is below 0.1 ppm, the sintering furnace is heated to a third temperature at a third heating rate and held at that temperature for a third time.

7. The vacuum sintering method for low-hydroxyl quartz glass as described in claim 6, characterized in that, The third heating rate is 3 to 5 °C / min, the third temperature is 1300 to 1400 °C, and the third time is 1 to 2 h.

8. The vacuum sintering method for low-hydroxyl quartz glass as described in claim 1, characterized in that, The sintering treatment of the quartz raw material includes the following steps: The sintering furnace is heated to a fourth temperature at a fourth heating rate and held at that temperature for a fourth time. The fourth heating rate is 2 to 3 °C / min, the fourth temperature is 1450 to 1550 °C, and the fourth time is 1 to 3 h. The sintering furnace is heated to a fifth temperature at a fifth heating rate and held at that temperature for a fifth time. The fifth heating rate is 1 to 2 °C / min, the fifth temperature is 1600 to 1650 °C, and the fifth time is 5 to 8 h.

9. The vacuum sintering method for low-hydroxyl quartz glass as described in claim 1, characterized in that, After the sintering treatment of the quartz raw material is completed, the following steps are also included: The sintering furnace is rapidly cooled until the temperature inside the sintering furnace drops below 800°C; The sintering furnace is slowly cooled until the temperature inside the sintering furnace drops below 100°C.

10. A vacuum sintering apparatus for low-hydroxyl quartz glass, characterized in that, The method for vacuum sintering low-hydroxyl quartz glass as described in any one of claims 1 to 9, wherein the low-hydroxyl quartz glass vacuum sintering equipment comprises: Sintering furnace; A vacuum assembly configured to evacuate the sintering furnace; A gas analysis component is provided on the pipeline between the vacuum assembly and the sintering furnace, and the gas analysis component is configured to detect the concentration of water molecules in the gas extracted from the sintering furnace.

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