Device and method for preparing low-hydroxyl quartz thick-wall tube by gas-electric melting method

Abstract

The invention relates to a device for preparing a low-hydroxyl quartz thick-walled tube by a gas-electric melting method, and belongs to the field of quartz thick-walled tube production. Comprising a supporting platform which is provided with a sliding guide rail. The main moving device drives the auxiliary moving device to horizontally reciprocate on the sliding guide rail; a main clamping and rotating device is mounted on the main moving device and drives the auxiliary clamping and rotating device to synchronously rotate; a heat preservation cabin located between the main moving device and the auxiliary moving device is further installed on the supporting platform. A base pipe channel allowing a base pipe to transversely penetrate through the heat preservation cabin is formed in the middle of the heat preservation cabin; a gas-electric heating device is mounted on the heater interface; the device is further provided with an igniter, and the igniter is connected with high-voltage electricity and used for igniting a combustor in the gas-electric heating device. Through resistance heating and thermal field control under the protective atmosphere, the quartz thick-wall pipe product capable of achieving deep dehydroxylation and selective wall thickening is successfully prepared, product cracking can be prevented, and product hydroxyl is reduced.

Description

Technical Field

[0001] This invention relates to an apparatus and method for producing quartz tubes, specifically an apparatus and method for producing low-hydroxyl quartz thick-walled tubes by gas electrofusion, belonging to the field of quartz thick-walled tube production. Background Technology

[0002] Quartz thick-walled tubes are widely used in semiconductor and photovoltaic fields due to their excellent properties of high temperature resistance, corrosion resistance and good thermal stability.

[0003] Currently, the main production methods for thick-walled quartz tubes are continuous melting, electrofusion, and gas refining. These methods produce products with drawbacks such as numerous bubbles and gas lines, high impurity content, and limited production specifications.

[0004] Gas-phase electrofusion, also known as "electrofusion" or "vapor deposition electrofusion," is one of the core technologies for preparing high-purity, low-hydroxyl quartz glass. It is particularly suitable for producing thick-walled, large-sized quartz products. The core of this method lies in "directly melting quartz raw materials through resistance heating in a protective atmosphere." Researching methods and specialized equipment for producing thick-walled, low-hydroxyl quartz tubes using gas-phase electrofusion is of great significance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing an apparatus for preparing low-hydroxyl quartz thick-walled tubes by gas electrofusion, which can effectively improve product performance and produce low-hydroxyl quartz thick-walled tubes with significantly improved physical and chemical properties.

[0006] Another technical problem to be solved by the present invention is to provide a method for preparing high-performance, classic and reliable low-hydroxyl quartz thick-walled tubes using the gas electrofusion method with the above-mentioned device.

[0007] The technical problem to be solved by this invention is achieved through the following technical solution. This invention is an apparatus for preparing low-hydroxyl quartz thick-walled tubes by gas electrofusion, characterized by: It includes a support platform, on which a sliding guide rail is installed; a main moving device and a secondary moving device are installed at both ends of the sliding guide rail, and the main moving device drives the secondary moving device to move horizontally back and forth on the sliding guide rail; The main moving device is equipped with a main clamping rotating device, and the auxiliary moving device is equipped with an auxiliary clamping rotating device. The main clamping rotating device drives the auxiliary clamping rotating device to rotate synchronously. An insulated chamber is also installed on the support platform between the main moving device and the auxiliary moving device. The insulated chamber is equipped with a cooling water inlet, a cooling water outlet, a heater interface, an exhaust port, and a diameter measuring instrument. The interior of the insulated chamber is lined with insulating bricks. The walls of the insulated chamber on all four sides and the top of the chamber are designed with a sandwich structure. Cooling water channels are laid within the sandwich structure. The cooling water inlet is located at the bottom of the insulated chamber. The cooling water channels are connected to the cooling water inlet at one end and to the cooling water outlet at the other end. The cooling water outlet is located at the top center of the insulated chamber. The diameter measuring instrument is located on the outer side of the insulated chamber and is connected to the control motors of the main moving device and the auxiliary moving device via signal lines. The insulation chamber has a base pipe channel in the middle for the base pipe to pass through the insulation chamber; A gas-electric heating device is installed on the heater interface; the gas-electric heating device includes an inner tube, an outer tube, and a middle tube disposed between the inner tube and the outer tube. The inner tube is connected to a first argon gas inlet and a first compressed air inlet; a second argon gas inlet and a second compressed air inlet are connected to the middle tube; and a third compressed air inlet is connected to the outer tube. The lower part of the middle layer tube extends downwards into the outer layer tube, and the plasma induction coil is sleeved on the outer side of the extended middle layer tube. The feeding port is located at the top of the gas-electric heating device and above the inner tube; The device is also equipped with an igniter, which is connected to high voltage electricity and used to ignite the burner in the gas-electric heating device.

[0008] A further preferred technical solution of the apparatus for preparing low-hydroxyl quartz thick-walled tubes by the gas electrofusion method described above is that the main moving device is controlled by a motor and the moving speed is adjustable; the auxiliary moving device is controlled by a motor and the moving speed is adjustable, and the moving speed is synchronized with the main moving device.

[0009] A further preferred technical solution of the apparatus for preparing low-hydroxyl quartz thick-walled tubes by the gas electrofusion method described above is that both the main clamping and rotating device and the auxiliary clamping and rotating device are provided with circumferentially arranged clamping claws for mounting the base tube on the main clamping and rotating device and the auxiliary clamping and rotating device.

[0010] A further preferred technical solution of the apparatus for preparing low-hydroxyl quartz thick-walled tubes by gas electrofusion method described above is that: the exhaust vents are arranged around the top of the heat-insulating chamber, and the heat-insulating chamber 5 is also provided with an observation window.

[0011] A further preferred technical solution of the apparatus for preparing low-hydroxyl quartz thick-walled tubes by the gas electrofusion method described above is that the cooling water channel is provided by a flow guide baffle laid in the interlayer around the insulation chamber and at the top.

[0012] A further preferred technical solution of the apparatus for preparing low-hydroxyl quartz thick-walled tubes by the gas electrofusion method described above is that the plasma induction coil is hollow, and cooling water is circulated inside for cooling.

[0013] This invention also discloses a method for preparing low-hydroxyl quartz thick-walled tubes by gas electrofusion, characterized in that the method uses the apparatus for preparing low-hydroxyl quartz thick-walled tubes by gas electrofusion as described in any of the above technical solutions, and the steps are as follows: (1) First, introduce cooling water into the cooling water channel and plasma induction coil, connect the high voltage to the igniter, and introduce argon gas into the inner and middle tubes. Adjust the first argon gas inlet flow rate to 5-10 m³ / h. 3 / h, adjust the second argon inlet flow rate to 8-10m 3 / h, preheat for 20-30 min; (2) After preheating, bring the igniter close to the bottom of the plasma induction coil, then connect the plasma induction coil to power and raise the voltage to 5-10kV to ignite; (3) Then immediately introduce compressed air into the outer pipe and adjust the flow rate of the third compressed air inlet to 10-15 m. 3 / h; Introduce argon and compressed air into the middle layer tube, and adjust the second argon inlet flow rate to 2-6 m³ / h. 3 / h, introduce compressed air into the second compressed air inlet, adjusting the flow rate to 3-8 m³ / h. 3 / h; Introduce compressed air into the inner layer pipe, and adjust the first compressed air inlet flow rate to 3-5 m³ / h. 3 / h, while adjusting the first argon inlet flow rate to 0 m 3 / h, and then bake the insulation chamber to raise the internal temperature to 1500-2000℃; (4) After the heating is completed, install the base tube onto the main clamping and rotating device and the auxiliary clamping and rotating device, and rotate synchronously. Adjust the rotation speed to 10-30 r / min; the main moving device and the auxiliary moving device drive the base tube to move laterally synchronously on the sliding guide rail at a speed of 5-10 mm / min. (5) The high-purity quartz sand is fed into the feed port. The high-purity quartz sand is heated into a molten state by the gas-electric heating device and deposited on the base pipe. The feeding amount is 30-80g / min. (6) The diameter measuring instrument performs online inspection of the product on the base pipe. After the outer diameter of the product meets the requirements, the feeding port stops feeding, the main clamping rotating device and the auxiliary clamping rotating device stop rotating, and the main moving device and the auxiliary moving device stop moving. After cooling, the product is removed from the base pipe and then cold-processed into a thick-walled pipe.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The apparatus and method for preparing low-hydroxyl quartz thick-walled tubes by gas electrofusion is a specialized apparatus and method for preparing low-hydroxyl quartz thick-walled tubes. It successfully produces quartz thick-walled tube products that can achieve deep dehydroxylation and selective thick walls by resistance heating and thermal field control under a protective atmosphere. It can prevent product cracking, reduce the hydroxyl content of the product, and the final product can serve as an indispensable basic material in many high-end manufacturing and technological fields. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of one structure of the present invention; Figure 2 This is a schematic diagram of a gas-electric heating device. Figure 3 This is a schematic diagram of the cooling water channel layout. Detailed Implementation

[0016] The specific technical solutions of the present invention are further described below to enable those skilled in the art to further understand the present invention, without constituting a limitation on its rights.

[0017] Example 1, referring to Figure 1 -3, An apparatus for preparing low-hydroxyl quartz thick-walled tubes by gas electrofusion: It includes a support platform 1, on which a sliding guide rail 2 is provided; a main moving device 3-1 and a secondary moving device 3-2 are installed at both ends of the sliding guide rail 2, and the main moving device 3-1 drives the secondary moving device 3-2 to move horizontally back and forth on the sliding guide rail 2; The main moving device 3-1 is equipped with a main clamping rotating device 4-1, and the auxiliary moving device 3-2 is equipped with an auxiliary clamping rotating device 4-2. The main clamping rotating device 4-1 drives the auxiliary clamping rotating device 4-2 to rotate synchronously. An insulated chamber 5 is also installed on the support platform 1, located between the main moving device 3-1 and the auxiliary moving device 3-2. The insulated chamber 5 is equipped with a cooling water inlet 5-1, a cooling water outlet 5-3, a heater interface 5-4, an exhaust port 5-5, and a diameter gauge 5-6. The interior of the insulated chamber 5 is lined with insulating bricks. The walls of the insulated chamber 5 around its perimeter and top are designed with a sandwich structure. Cooling water channels 5-2 are laid within the sandwich structure. The cooling water inlet 5-1 is located at the bottom of the insulated chamber 5. The cooling water channel 5-2 is connected at its first end to the cooling water inlet 5-1 and at its last end to the cooling water outlet 5-3. The cooling water outlet 5-3 is located at the top of the insulated chamber 5. The heater interface 5-4 is located at the top center of the insulated chamber 5. The diameter gauge 5-6 is located on the outside of the insulated chamber 5 and is connected to the control motors of the main moving device 3-1 and the auxiliary moving device 3-2 via signal lines. The insulation chamber 5 has a base pipe channel in the middle for the base pipe 6 to pass through the insulation chamber 5; A gas-electric heating device 7 is installed on the heater interface 5-4; the gas-electric heating device 7 includes an inner tube 7-1, an outer tube 7-7, and a middle tube 7-4 disposed between the inner tube 7-1 and the outer tube 7-7. The inner tube 7-1 is connected to the first argon gas inlet 7-2 and the first compressed air inlet 7-3; the middle tube 7-4 is connected to the second argon gas inlet 7-5 and the second compressed air inlet 7-6; the outer tube 7-7 is connected to the third compressed air inlet 7-8. The lower part of the middle layer tube 7-4 extends downwards beyond the outer layer tube 7-7, and the plasma induction coil 7-9 is sleeved on the outer side of the extended part of the middle layer tube 7-4. The feeding port 8 is located at the top of the gas-electric heating device 7 and above the inner tube 7-1; The device is also equipped with an igniter 9, which is connected to high voltage electricity and is used to ignite the burner 10 in the gas-electric heating device 7.

[0018] The main moving device 3-1 is controlled by a motor and its moving speed is adjustable; the auxiliary moving device 3-2 is controlled by a motor and its moving speed is adjustable, and its moving speed is synchronized with that of the main moving device 3-1.

[0019] Both the main clamping rotating device 4-1 and the auxiliary clamping rotating device 4-2 are equipped with circumferentially arranged clamping claws for mounting the base tube 6 on the main clamping rotating device 4-1 and the auxiliary clamping rotating device 4-2. Exhaust vents 5-5 are located around the top of the insulation chamber 5, which also has observation windows 11. Cooling water channels 5-2 are laid in the interlayer around the perimeter and top of the insulation chamber 5 using flow guide baffles. The plasma induction coil 7-9 is hollow, with cooling water flowing through its interior for cooling.

[0020] Example 2: A method for preparing low-hydroxyl quartz thick-walled tubes by gas electrofusion, using the apparatus for preparing low-hydroxyl quartz thick-walled tubes as described in Example 1, and comprising the following steps: (1) First, cool water is introduced into the cooling water channel and the plasma induction coil. The high voltage is connected to the igniter, and argon gas is introduced into the inner tube and the middle tube. The flow rate of the first argon gas inlet is adjusted to 5 m³ / s. 3 / h, adjust the second argon inlet flow rate to 8 m 3 / h, preheat for 20 min; (2) After preheating, bring the igniter close to the bottom of the plasma induction coil, then connect the plasma induction coil to power and raise the voltage to 5kV to ignite; (3) Then immediately introduce compressed air into the outer pipe and adjust the flow rate of the third compressed air inlet to 10m. 3 / h; Introduce argon and compressed air into the middle layer tube, and adjust the second argon inlet flow rate to 2 m³ / h. 3 / h, introduce compressed air into the second compressed air inlet, and adjust the flow rate to 3 m³ / h. 3 / h; Introduce compressed air into the inner tube, and adjust the first compressed air inlet flow rate to 3 m³ / h. 3 / h, while adjusting the first argon inlet flow rate to 0 m 3 / h, and then bake the insulation chamber to raise the internal temperature to 1500℃; (4) After the heating is completed, the base tube 6 is installed on the main clamping rotating device 4-1 and the auxiliary clamping rotating device 4-2 and rotated synchronously. The rotation speed is adjusted to 10 r / min. The main moving device 3-1 and the auxiliary moving device 3-2 drive the base tube 6 to move laterally synchronously on the sliding guide rail 2 at a speed of 5 mm / min. (5) The raw material high-purity quartz sand is fed into the feed port 8. The high-purity quartz sand is heated into a molten state by the gas-electric heating device 7 and deposited on the base pipe 6. The feeding rate is 30g / min. (6) The diameter measuring instrument 5-6 performs online inspection on the product on the base pipe 6. After the outer diameter of the product meets the requirements, the feeding port 8 stops feeding, the main clamping rotating device 4-1 and the auxiliary clamping rotating device 4-2 stop rotating, and the main moving device 3-1 and the auxiliary moving device 3-2 stop moving. After cooling, the product is removed from the base pipe 6 and then cold-processed into a thick-walled pipe.

[0021] Example 3: A method for preparing low-hydroxyl quartz thick-walled tubes by gas electrofusion, using the apparatus for preparing low-hydroxyl quartz thick-walled tubes as described in Example 1, and comprising the following steps: (1) First, cool water is introduced into the cooling water channel and the plasma induction coil. The high voltage is connected to the igniter, and argon gas is introduced into the inner tube and the middle tube. The flow rate of the first argon gas inlet is adjusted to 8 m³ / s. 3 / h, adjust the second argon inlet flow rate to 8 m 3 / h, preheat for 20 min; (2) After preheating, bring the igniter close to the bottom of the plasma induction coil, then connect the plasma induction coil to power and raise the voltage to 10kV to ignite; (3) Then immediately introduce compressed air into the outer pipe and adjust the flow rate of the third compressed air inlet to 15 m. 3 / h; Introduce argon and compressed air into the middle layer tube, and adjust the second argon inlet flow rate to 6 m³ / h. 3 / h, introduce compressed air into the second compressed air inlet, and adjust the flow rate to 8 m³ / h. 3 / h; Introduce compressed air into the inner tube and adjust the first compressed air inlet flow rate to 5 m³ / h. 3 / h, while adjusting the first argon inlet flow rate to 0 m 3 / h, and then bake the insulation chamber to raise the internal temperature to 2000℃; (4) After the heating is completed, the base tube 6 is installed on the main clamping rotating device 4-1 and the auxiliary clamping rotating device 4-2 and rotated synchronously. The rotation speed is adjusted to 30 r / min. The main moving device 3-1 and the auxiliary moving device 3-2 drive the base tube 6 to move laterally synchronously on the sliding guide rail 2 at a speed of 10 mm / min. (5) The raw material high-purity quartz sand is fed into the feed port 8. The high-purity quartz sand is heated into a molten state by the gas-electric heating device 7 and deposited on the base pipe 6. The feeding rate is 80g / min. (6) The diameter measuring instrument 5-6 performs online inspection on the product on the base pipe 6. After the outer diameter of the product meets the requirements, the feeding port 8 stops feeding, the main clamping rotating device 4-1 and the auxiliary clamping rotating device 4-2 stop rotating, and the main moving device 3-1 and the auxiliary moving device 3-2 stop moving. After cooling, the product is removed from the base pipe 6 and then cold-processed into a thick-walled pipe.

[0022] Example 4: A method for preparing low-hydroxyl quartz thick-walled tubes by gas electrofusion, using the apparatus for preparing low-hydroxyl quartz thick-walled tubes as described in Example 1, and comprising the following steps: (1) First, cool water is introduced into the cooling water channel and the plasma induction coil. The high voltage is connected to the igniter, and argon gas is introduced into the inner tube and the middle tube. The flow rate of the first argon gas inlet is adjusted to 10 m³ / s. 3 / h, adjust the second argon inlet flow rate to 9m 3 / h, preheat for 25min; (2) After preheating, bring the igniter close to the bottom of the plasma induction coil, then connect the plasma induction coil to power and raise the voltage to 8kV to ignite; (3) Then immediately introduce compressed air into the outer pipe and adjust the flow rate of the third compressed air inlet to 12 m. 3 / h; Introduce argon and compressed air into the middle layer tube, and adjust the second argon inlet flow rate to 4 m³ / h. 3 / h, introduce compressed air into the second compressed air inlet, and adjust the flow rate to 5 m³ / h. 3 / h; Introduce compressed air into the inner layer pipe, and adjust the first compressed air inlet flow rate to 4 m³ / h. 3 / h, while adjusting the first argon inlet flow rate to 0 m 3 / h, and then bake the insulation chamber to raise the internal temperature to 1800℃; (4) After the heating is completed, the base tube 6 is installed on the main clamping rotating device 4-1 and the auxiliary clamping rotating device 4-2 and rotated synchronously. The rotation speed is adjusted to 20 r / min. The main moving device 3-1 and the auxiliary moving device 3-2 drive the base tube 6 to move laterally synchronously on the sliding guide rail 2 at a speed of 8 mm / min. (5) The raw material high-purity quartz sand is fed into the feed port 8. The high-purity quartz sand is heated into a molten state by the gas-electric heating device 7 and deposited on the base pipe 6. The feeding rate is 55g / min. (6) The diameter measuring instrument 5-6 performs online inspection on the product on the base pipe 6. After the outer diameter of the product meets the requirements, the feeding port 8 stops feeding, the main clamping rotating device 4-1 and the auxiliary clamping rotating device 4-2 stop rotating, and the main moving device 3-1 and the auxiliary moving device 3-2 stop moving. After cooling, the product is removed from the base pipe 6 and then cold-processed into a thick-walled pipe.

[0023] Example 5, Experimental Scheme: Verification of the Effect of Gas Electrofusion Method for Preparing Low-Hydroxy Quartz Thick-Walled Tubes I. Experimental Objective: The quantitative verification demonstrates that the quartz thick-walled tubes prepared by the gas-electrofusion method of this invention have extremely low hydroxyl (-OH) content. The comprehensive advantages of this technology in terms of optical performance, bubble density, purity, mechanical strength, and thermal stability are systematically evaluated. The differences between this invention and traditional gas refining methods and conventional electrofusion methods in terms of key product performance indicators are clearly defined.

[0024] II. Experimental Materials and Equipment Preparation equipment and methods: Experimental group: The gas electrofusion method for preparing quartz tubes described in Example 1 and the method described in Example 4.

[0025] Control group A: Traditional gas refining lathe.

[0026] Control group B: Conventional vacuum electric melting furnace.

[0027] Raw materials: High-purity quartz sand or crystal powder of the same batch and purity grade.

[0028] Target product specifications: Quartz thick-walled tube with an outer diameter of Φ50mm, a wall thickness of 10mm, and a length of 200mm.

[0029] Testing instruments: Fourier transform infrared spectroscopy (FTIR): used to determine hydroxyl content; Ultraviolet-visible-near-infrared spectrophotometer: used to determine optical transmittance; High-resolution optical / electron microscopes: used to observe bubbles, impurities, and microstructures; Inductively coupled plasma mass spectrometry (ICP-MS): used to analyze the content of metal impurities; Universal testing machine: used to test flexural strength; Thermal expansion coefficient tester: used to test thermal stability; Laser particle size analyzer (used for raw material identification).

[0030] III. Experimental Procedure Step 1: Sample Preparation Divide the same batch of raw materials into three equal portions.

[0031] Experimental group: Quartz thick-walled tube samples were prepared using the apparatus described in Example 1 and the method described in Example 2.

[0032] Control group A: Quartz tubes were prepared by melt deposition in a hydrogen-oxygen flame using the conventional gas refining method.

[0033] Control group B: Quartz tubes were prepared by melting quartz sand in a vacuum or atmospheric environment using the conventional electrofusion method.

[0034] All prepared quartz tube samples were subjected to the same annealing treatment to eliminate internal stress.

[0035] Using diamond cutting / grinding tools, the three sets of quartz tubes were machined into identical standard samples that met all testing requirements, and clearly marked.

[0036] Step 2: Performance Testing and Characterization The following parallel tests were performed on all three groups of samples: Hydroxyl (-OH) content test: Methods: The characteristic absorption peak of hydroxyl groups was measured using FTIR in the wavelength range of approximately 2.7 μm to 2.8 μm (near 3700 cm⁻¹ wavenumber).

[0037] Calculation: Based on Lambert-Beer's law, the hydroxyl content (unit: ppm) is accurately calculated using the standard formula COH = (K / d) * ln(T0 / T) (where K is a constant, d is the sample thickness, T0 is the baseline transmittance, and T is the transmittance at the characteristic peak).

[0038] Expected results: The experimental group samples should be significantly lower than the two control groups, especially much lower than the gas refining samples.

[0039] Optical performance testing: Methods: Transmittance curves were measured in the deep ultraviolet (~190 nm) to near-infrared (~3000 nm) bands using a UV-Vis-NIR spectrophotometer.

[0040] Key metrics: Cutoff wavelength and transmittance in the ultraviolet band (190nm-250nm); Peak transmittance in the visible light band (550nm) (theoretically should be >92%). The degree of transmittance dip near the hydroxyl absorption peak (2.7 μm); Expected outcome: Due to the low hydroxyl content, the experimental group samples should have minimal transmittance loss in the infrared band; at the same time, due to their high purity, they should exhibit excellent ultraviolet transmittance.

[0041] Bubble and inclusion assessment: Methods: The number and size distribution of bubbles per unit volume were observed and counted using a high-power optical microscope against a dark background.

[0042] Standards: Refer to relevant standards (such as the bubble rating of quartz glass for semiconductors).

[0043] Expected outcome: Since the gas-electric melting method involves powder melting and the process is controllable, the bubble density should be better than or equivalent to that of the conventional electric melting method, and significantly better than the gas refining method.

[0044] Metal impurity content analysis: Methods: After sampling and digestion, the content of key metal impurities (such as Al, Fe, K, Na, Li, Cu, etc.) was detected by ICP-MS (unit: ppb level).

[0045] The inventors anticipate that all three samples should maintain high purity. If high-purity gaseous raw materials are used in the gas electrofusion method, the content of impurities such as alkali metals may be even lower.

[0046] Mechanical performance testing: Method: Three-point flexural strength test was performed using a universal testing machine.

[0047] Sample: Cut the quartz tube into strips of the specified size.

[0048] The inventors anticipate that samples with fewer bubbles and impurities and a denser structure generally exhibit higher mechanical strength. The experimental group and samples from the conventional electrofusion method may outperform those from the gas refining method.

[0049] Thermal stability assessment: Method: The coefficient of thermal expansion (CTE) of the sample from room temperature to 1000℃ was measured using a coefficient of thermal expansion tester.

[0050] The inventors anticipated that all high-purity quartz glasses should have extremely low and similar CTE values. This is primarily used to confirm whether the material is a standard quartz glass phase.

[0051] IV. Data Recording and Analysis Use the following table to record and compare data:

[0052] V. Experimental Conclusions Based on a comprehensive analysis of the above test results, the following conclusions can be drawn: Technical effectiveness verification: The low hydroxyl content has been confirmed: The unique equipment and process of the gas electrofusion method and the vacuum environment effectively remove moisture from the raw materials and prevent the introduction of hydroxyl groups during processing. Experimental data will directly prove its excellence in this indicator.

[0053] Excellent overall performance: This technology not only leads in low hydroxyl content, but also achieves high UV / IR transmittance, high purity, low bubble content and high mechanical strength.

[0054] Summary of technical advantages: Performance advantages: Particularly suitable for high-end applications that are sensitive to moisture, such as high-power laser windows, fiber optic preform liners, and semiconductor high-temperature process cavities.

[0055] Process advantages: Compared with gas refining, it avoids the pollution caused by hydrogen-oxygen flame; compared with some electrofusion methods, its dehydration step is more proactive and has a higher tolerance for raw materials.

Claims

1. A device for preparing low-hydroxyl quartz thick-walled tube by gas-electricity fusion method, characterized in that: it comprises a supporting platform, a sliding guide rail arranged on the supporting platform, a main moving device and a secondary moving device installed at both ends of the sliding guide rail, the main moving device drives the secondary moving device to move horizontally and reciprocally on the sliding guide rail, a main clamping and rotating device installed on the main moving device, a secondary clamping and rotating device installed on the secondary moving device, the main clamping and rotating device drives the secondary clamping and rotating device to rotate synchronously, a heat preservation cabin installed on the supporting platform and located between the main moving device and the secondary moving device, the heat preservation cabin is provided with a cooling water inlet, a cooling water outlet, a heater interface, an exhaust port and a diameter measuring instrument, heat preservation bricks are laid in the heat preservation cabin, the periphery and the top cabin wall of the heat preservation cabin are designed as a sandwich, a cooling water channel is laid in the sandwich, the cooling water inlet is arranged at the lower part of the heat preservation cabin, the first end of the cooling water channel is connected with the cooling water inlet, the last end of the cooling water channel is connected with the cooling water outlet, the cooling water outlet is arranged at the upper part of the heat preservation cabin, the heater interface is arranged at the middle part of the top of the heat preservation cabin, the diameter measuring instrument is arranged on the outside of the heat preservation cabin, and the diameter measuring instrument is connected with the control motors of the main moving device and the secondary moving device through signal lines, a base tube channel is arranged in the middle part of the heat preservation cabin and used for allowing the base tube to pass through the heat preservation cabin, a gas-electricity heating device is installed on the heater interface, the gas-electricity heating device comprises an inner layer tube, an outer layer tube and a middle layer tube arranged between the inner layer tube and the outer layer tube, the inner layer tube is connected with a first argon inlet and a first compressed air inlet, the middle layer tube is connected with a second argon inlet and a second compressed air inlet, and the outer layer tube is connected with a third compressed air inlet, the lower part of the middle layer tube extends out of the outer layer tube, and a plasma induction coil is sleeved on the outer side of the extended part of the middle layer tube, a feeding port is arranged at the top of the gas-electricity heating device and above the inner layer tube, and an igniter is arranged on the device and connected with high-voltage electricity and used for igniting the burner in the gas-electricity heating device. The main moving device is controlled to move by a motor, and the moving speed is adjustable; the secondary moving device is controlled to move by a motor, and the speed is adjustable, and the moving speed is synchronous with that of the main moving device. The main clamping and rotating device and the secondary clamping and rotating device are both provided with circumferentially arranged clamping claws and used for mounting the base tube on the main clamping and rotating device and the secondary clamping and rotating device. The exhaust ports are arranged around the top of the heat preservation cabin, and the heat preservation cabin is further provided with an observation window. The cooling water channel is laid in the sandwich of the periphery and the top of the heat preservation cabin by using a flow guide baffle. The plasma induction coil is hollow, and the inside of the plasma induction coil is used for passing cooling water to cool. The method uses the device for preparing low-hydroxyl quartz thick-walled tube by gas-electricity fusion method according to any one of claims 1-6, and the steps are as follows: (2) after the preheating is completed, the igniter is arranged close to the bottom of the plasma induction coil, then the plasma induction coil is connected with electricity, the voltage is raised to 5-10 kv, and ignition is performed; (4) after the temperature rising is completed, the base tube is mounted on the main clamping and rotating device and the secondary clamping and rotating device, and the rotating speed is adjusted to 10-30 r / min; the main moving device and the secondary moving device drive the base tube to move horizontally and synchronously on the sliding guide rail, and the moving speed is 5-10 mm / min. ​ 2. The apparatus for the electrofusion production of low-hydroxy quartz thick-walled pipes according to claim 1, characterized in that: ​ 3. The apparatus for the electrofusion production of low-hydroxy quartz thick-walled pipes according to claim 1, characterized in that: ​ 4. The apparatus for the electrofusion production of low-hydroxy quartz thick-walled pipes according to claim 1, characterized in that: ​ 5. The apparatus for the electrofusion production of low-hydroxy quartz thick-walled pipes according to claim 1, characterized in that: ​ 6. The apparatus for the electrofusion production of low-hydroxy quartz thick-walled pipes according to claim 1, characterized in that: ​ 7. A method of making a low-hydroxy quartz thick-walled tube by the gas- electric fusion process, characterized in that ​ (1) First, the cooling water is passed into the cooling water channel and the plasma induction coil, the high-voltage electricity is connected to the igniter, the argon is passed into the inner layer pipe and the middle layer pipe, the first argon inlet flow is adjusted to 5-10 m 3 / h, the second argon inlet flow is adjusted to 8-10 m 3 / h, and preheating is performed for 20-30 min; ​ (3) Then immediately pass compressed air into the outer tube, adjust the third compressed air inlet flow to 10-15 m 3 / h; pass argon and compressed air into the middle tube, adjust the second argon inlet flow to 2-6 m 3 / h, pass compressed air into the second compressed air inlet, adjust the flow to 3-8 m 3 / h; pass compressed air into the inner tube, adjust the first compressed air inlet flow to 3-5 m 3 / h, at the same time adjust the first argon inlet flow to 0 m 3 / h, then bake the heat preservation cabin, and raise the internal temperature to 1500-2000℃; ​ (5) The raw material high-purity quartz sand is put into from the feeding port, the high-purity quartz sand is heated into a molten state by the gas-electric heating device and deposited on the base pipe, and the feeding amount is 30-80 g / min; (6) The product on the base pipe is detected on line by the diameter measuring instrument, after the outer diameter of the product meets the requirements, the feeding port stops feeding, the main clamping rotating device and the auxiliary clamping rotating device stop rotating, the main moving device and the auxiliary moving device stop moving; after cooling, the product is unloaded, and the product is removed from the base pipe and then made into a thick-walled pipe by cold working.

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