Process method for melting quartz tube through cooperation of microwaves and plasmas

Abstract

The invention relates to the technical field of melting preparation of quartz materials, in particular to a technological method for melting a quartz tube through cooperation of microwaves and plasmas. According to the technological method for melting the quartz tube through the cooperation of the microwaves and the plasmas, through the chemical cooperation mechanism of microwave molecule activation, plasma cooperation melting and heat preservation annealing, the problems that traditional electric heating is high in energy consumption, many in metal residues and uneven in thermal field are effectively solved, the technology is stable, and the technological method is suitable for mass production of high-purity quartz tubes.

Description

Technical Field

[0001] This invention relates to the field of quartz material melting and preparation technology, specifically to a process method for the synergistic melting of quartz tubes using microwave and plasma. Background Technology

[0002] Quartz tubes are widely used in optoelectronics, semiconductors, and other fields due to their excellent high-temperature resistance, light transmittance, and chemical stability. Traditional quartz tube melting processes primarily rely on electric heating. Because of the high lattice energy of quartz, traditional electric heating requires temperatures to reach 2000-2200℃ to break the Si-O bonds and achieve melting, resulting in energy consumption typically ≥8.5 kW・h / kg. Electric heating also easily leads to uneven thermal fields, with electrode heating causing localized overheating, which can cause deviations in quartz tube wall thickness and increased internal bubble rate. Furthermore, electric heating introduces electrode contamination; metal electrodes (such as Mo and W) are prone to volatilization at high temperatures, resulting in residual metal ions in the quartz tube, affecting optical performance. Therefore, it is essential to develop a low-energy-consumption process for melting quartz tubes that produces a uniform thermal field and low residual metal ions. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention aims to provide a process for the synergistic melting of quartz tubes using microwave and plasma. Through a chemical synergistic mechanism of "microwave molecular activation - plasma synergistic melting - heat preservation annealing," it effectively solves the problems of high energy consumption, excessive metal residue, and uneven thermal field associated with traditional electric heating. The process is stable and suitable for the mass production of high-purity quartz tubes.

[0004] This invention discloses a process for synergistic melting of quartz tubes using microwave and plasma, comprising the following preparation steps: S1 Quartz Raw Material Pretreatment: Quartz sand is soaked in a mixture of hydrofluoric acid and nitric acid, then rinsed with deionized water and dried, and pressed into a tubular blank. S2 Microwave pretreatment: The tubular blank obtained in step S1 is placed in a 2.45GHz microwave resonant cavity, the microwave power is set, and it is treated in an inert gas atmosphere to activate the Si-O bond vibration. S3 Co-melting: The pre-treated billet after steps S1 and S2 is transferred into the plasma torch, a gas mixture of Ar and O2 is introduced, the microwave power of step S2 is maintained, the plasma power, plasma working gas flow rate and temperature are set, and then melting is carried out. S4 heat preservation annealing: Control the cooling rate to cool to 1150~1400℃, hold for 20~45min, and then cool to 25℃.

[0005] Preferably, in the S1 quartz raw material pretreatment step, the concentration of hydrofluoric acid is 0.5~1 mol / L.

[0006] Preferably, in the S1 quartz raw material pretreatment step, the concentration of the nitric acid is 1~2 mol / L.

[0007] Preferably, in the S1 quartz raw material pretreatment step, the volume ratio of hydrofluoric acid to nitric acid is 1:3.

[0008] Preferably, in the S2 microwave preprocessing step, the microwave power is 300~800W.

[0009] Preferably, in the S3 co-melting step, the volume ratio of Ar to O2 is (4~9):1.

[0010] Preferably, in the S3 co-melting step, the plasma working gas flow rate is 100~200mL / min.

[0011] Preferably, in the S3 co-melting step, the plasma power is 1000~2000W.

[0012] Preferably, in the S3 co-melting step, the melting temperature is 1700~1950℃; the melting time is 4~9min.

[0013] Preferably, in the S4 heat preservation annealing step, the cooling rate is 5~10℃ / min.

[0014] Compared with the prior art, the present invention provides a process for the synergistic melting of quartz tubes using microwave and plasma, which has the following beneficial effects: (1) Significantly reduced energy consumption: Traditional electric heating (Comparative Example 1) consumes 8.8 kW·h / kg, and plasma heating alone (Comparative Example 4) consumes 7.3 kW·h / kg. However, the process method provided by the present invention activates Si-O bonds with microwaves and works in conjunction with the plasma thermal field. The energy consumption of Examples 1 to 6 is only 4.2 to 6.2 kW·h / kg, and Example 5 reaches 4.2 kW·h / kg, which is 52.3% lower than the traditional process, effectively solving the problem of high energy consumption.

[0015] (2) Reduce metal residue: In the traditional process (Comparative Example 1), the metal residue is 18.5 ppm due to the volatilization of the Mo electrode; the process method provided by the present invention has no electrode design, and the residue in Examples 1 to 6 is ≤0.8 ppm, and in Example 5 it is only 0.2 ppm, which can meet the high purity requirements of the semiconductor field.

[0016] (3) Optimize the thermal field and molding accuracy: The traditional process (Comparative Example 1) has a temperature difference of 55℃ and a wall thickness deviation of 0.38mm, while the plasma alone (Comparative Example 4) has a temperature difference of 28℃. The process method provided by this invention uses microwave synergy to make the thermal field uniform. The temperature difference in Examples 1 to 6 is 5 to 12℃, and the temperature difference in Example 5 is 5℃ with a wall thickness deviation of 0.09mm, which is 76.3% lower than the traditional process. The bubble rate is only 0.4%, which effectively controls molding defects.

[0017] (4) Improved optical performance: The transmittance of the traditional process (Comparative Example 1) is 82%, and the transmittance of the non-microwave pretreatment (Comparative Example 2) is 87%; the process method provided by the present invention reduces defects and heat preservation annealing. The transmittance of Examples 1 to 6 is 86% to 93%, and Example 5 reaches 93%, which is 13.4% higher than the traditional process. The finished quartz tube can be adapted to optical applications.

[0018] (5) Stable and efficient process: The parameters of Examples 1 to 6 were adjusted to produce qualified products with small performance fluctuations; no electrode maintenance is required, which is suitable for industrial mass production and is more practical than microwave alone (Comparative Example 3) and plasma alone (Comparative Example 4). Detailed Implementation

[0019] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0020] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0021] Example 1: A process for fusion of microwave and plasma into a quartz tube, comprising the following steps: S1 Quartz Raw Material Pretreatment: High-purity quartz sand (SiO2 purity ≥ 99.99%, particle size 50~100μm) is soaked in a mixture of 0.5mol / L hydrofluoric acid and 1mol / L nitric acid for 20~30min, where the volume ratio of hydrofluoric acid to nitric acid is 1:3, to remove surface metallic impurities. Then it is rinsed with deionized water until the pH value is 7, and dried at 80~100℃ for 2~3h. Then it is pressed into a tubular blank (outer diameter 35mm, inner diameter 20mm, length 150mm).

[0022] S2 Microwave Pretreatment: The tubular blank obtained in step S1 is placed in the center of a microwave resonant cavity with a frequency of 2.45 GHz, a microwave power of 300 W, and a treatment time of 12 min, under an argon atmosphere with a flow rate of 75 mL / min to activate the Si-O bond vibration. At this time, the internal temperature of the blank is ≤300℃, with no obvious heating, only molecular activation.

[0023] S3 Co-melting: The pretreated billet from steps S1 and S2 is transferred into a plasma torch, and a mixture of Ar and O2 gases is introduced, with a volume ratio of Ar to O2 of 4:1. The microwave power from step S2 is maintained, the plasma power is set to 1000W, the plasma working gas flow rate is 100mL / min, and the melting temperature is 1700℃ for 4 minutes. The activated Si-O bonds break rapidly in the plasma, forming molten SiO2. The Ar-O2 mixture inhibits SiO2 reduction, preventing the formation of elemental Si, while O2 replenishes unsaturated bonds on the surface, reducing defects. S4 heat preservation annealing: After melting, maintain plasma power at 600W and microwave power at 150W, control the cooling rate at 5℃ / min, reduce from 1700℃ to 1400℃, and hold for 20min; after holding, turn off the microwave, reduce plasma power to 250W, and allow to cool naturally to 25℃ to obtain the finished quartz tube.

[0024] Example 2: A process for fusion of microwave and plasma into a quartz tube, comprising the following steps: S1 Quartz Raw Material Pretreatment: High-purity quartz sand (SiO2 purity ≥ 99.99%, particle size 50~100μm) is soaked in a mixture of 0.6mol / L hydrofluoric acid and 1.2mol / L nitric acid for 20~30min, where the volume ratio of hydrofluoric acid to nitric acid is 1:3, to remove surface metallic impurities. Then it is rinsed with deionized water until the pH value is 7, and dried at 80~100℃ for 2~3h. Then it is pressed into a tubular blank (outer diameter 35mm, inner diameter 20mm, length 150mm).

[0025] S2 Microwave Pretreatment: The tubular blank obtained in step S1 is placed in the center of a microwave resonant cavity with a frequency of 2.45 GHz, a microwave power of 400 W, and a treatment time of 12 min, under an argon atmosphere with a flow rate of 75 mL / min to activate the Si-O bond vibration. At this time, the internal temperature of the blank is ≤300℃, with no obvious heating, only molecular activation.

[0026] S3 Co-melting: The pretreated billet from steps S1 and S2 is transferred into a plasma torch, and a mixture of Ar and O2 gases is introduced, with a volume ratio of Ar to O2 of 5:1. The microwave power from step S2 is maintained, the plasma power is set to 1200W, the plasma working gas flow rate is 120mL / min, and the melting temperature is 1750℃. Melting is then carried out for 5 minutes. The activated Si-O bonds break rapidly in the plasma, forming molten SiO2. The Ar-O2 mixture inhibits SiO2 reduction, preventing the formation of elemental Si, while O2 replenishes unsaturated bonds on the surface, reducing defects. S4 heat preservation annealing: After melting, maintain plasma power at 600W and microwave power at 150W, control the cooling rate at 6℃ / min, reduce from 1750℃ to 1350℃, and hold for 25min; after holding, turn off the microwave, reduce plasma power to 250W, and allow to cool naturally to 25℃ to obtain the finished quartz tube.

[0027] Example 3: A process for fusion of microwave and plasma into a quartz tube, comprising the following steps: S1 Quartz Raw Material Pretreatment: High-purity quartz sand (SiO2 purity ≥ 99.99%, particle size 50~100 μm) is soaked in a mixture of 0.7mol / L hydrofluoric acid and 1.4mol / L nitric acid for 20~30 min, where the volume ratio of hydrofluoric acid to nitric acid is 1:3, to remove surface metallic impurities. Then it is rinsed with deionized water until the pH value is 7, and dried at 80~100℃ for 2~3 h. Then it is pressed into a tubular blank (outer diameter 35 mm, inner diameter 20 mm, length 150 mm).

[0028] S2 Microwave Pretreatment: The tubular blank obtained in step S1 is placed in the center of a microwave resonant cavity with a frequency of 2.45 GHz, a microwave power of 500 W, and a treatment time of 12 min, under an argon atmosphere with a flow rate of 75 mL / min to activate Si-O bond vibrations. At this time, the internal temperature of the blank is ≤300℃, with no obvious heating, only molecular activation.

[0029] S3 Co-melting: The pretreated billet from steps S1 and S2 is transferred into a plasma torch, and a mixture of Ar and O2 gases is introduced, with a volume ratio of Ar to O2 of 6:1. The microwave power from step S2 is maintained, the plasma power is set to 1400W, the plasma working gas flow rate is 140mL / min, and the melting temperature is 1800℃ for 6 minutes. The activated Si-O bonds break rapidly in the plasma, forming molten SiO2. The Ar-O2 mixture inhibits SiO2 reduction, preventing the formation of elemental Si, while O2 replenishes unsaturated bonds on the surface, reducing defects. S4 heat preservation annealing: After melting, maintain plasma power at 600W and microwave power at 150W, control the cooling rate at 7℃ / min, reduce from 1800℃ to 1300℃, and hold for 30min; after holding, turn off the microwave, reduce plasma power to 250W, and allow to cool naturally to 25℃ to obtain the finished quartz tube.

[0030] Example 4: A process for fusion of microwave and plasma into a quartz tube, comprising the following steps: S1 Quartz Raw Material Pretreatment: High-purity quartz sand (SiO2 purity ≥ 99.99%, particle size 50~100 μm) is soaked in a mixture of 0.8 mol / L hydrofluoric acid and 1.6 mol / L nitric acid for 20~30 min, where the volume ratio of hydrofluoric acid to nitric acid is 1:3, to remove surface metallic impurities. Then it is rinsed with deionized water until the pH value is 7, and dried at 80~100℃ for 2~3 h. Then it is pressed into a tubular blank (outer diameter 35 mm, inner diameter 20 mm, length 150 mm).

[0031] S2 Microwave Pretreatment: The tubular blank obtained in step S1 is placed in the center of a microwave resonant cavity with a frequency of 2.45 GHz, a microwave power of 600 W, and a treatment time of 12 min, under an argon atmosphere with a flow rate of 75 mL / min to activate the Si-O bond vibration. At this time, the internal temperature of the blank is ≤300℃, with no obvious heating, only molecular activation.

[0032] S3 Co-melting: The pretreated billet from steps S1 and S2 is transferred into a plasma torch, and a mixture of Ar and O2 gases is introduced, with a volume ratio of Ar to O2 of 7:1. The microwave power from step S2 is maintained, the plasma power is set to 1600W, the plasma working gas flow rate is 160mL / min, and the melting temperature is 1850℃ for 7 minutes. The activated Si-O bonds break rapidly in the plasma, forming molten SiO2. The Ar-O2 mixture inhibits SiO2 reduction, preventing the formation of elemental Si, while O2 replenishes unsaturated bonds on the surface, reducing defects. S4 heat preservation annealing: After melting, maintain plasma power at 600W and microwave power at 150W, control the cooling rate at 8℃ / min, reduce from 1850℃ to 1250℃, and hold for 35min; after holding, turn off the microwave, reduce plasma power to 250W, and allow to cool naturally to 25℃ to obtain the finished quartz tube.

[0033] Example 5: A process for fusion of microwave and plasma into a quartz tube, comprising the following steps: S1 Quartz Raw Material Pretreatment: High-purity quartz sand (SiO2 purity ≥ 99.99%, particle size 50~100 μm) is soaked in a mixture of 0.9 mol / L hydrofluoric acid and 1.8 mol / L nitric acid for 20~30 min, where the volume ratio of hydrofluoric acid to nitric acid is 1:3, to remove surface metallic impurities. Then it is rinsed with deionized water until the pH value is 7, and dried at 80~100℃ for 2~3 h. Then it is pressed into a tubular blank (outer diameter 35 mm, inner diameter 20 mm, length 150 mm).

[0034] S2 Microwave Pretreatment: The tubular blank obtained in step S1 is placed in the center of a microwave resonant cavity with a frequency of 2.45 GHz, a microwave power of 700 W, and a treatment time of 12 min, under an argon atmosphere with a flow rate of 75 mL / min to activate the Si-O bond vibration. At this time, the internal temperature of the blank is ≤300℃, with no obvious heating, only molecular activation.

[0035] S3 Co-melting: The pretreated billet from steps S1 and S2 is transferred into a plasma torch, and a mixture of Ar and O2 gases is introduced, with a volume ratio of Ar to O2 of 8:1. The microwave power from step S2 is maintained, the plasma power is set to 1800W, the plasma working gas flow rate is 180mL / min, and the melting temperature is 1900℃ for 8 minutes. The activated Si-O bonds break rapidly in the plasma, forming molten SiO2. The Ar-O2 mixture inhibits SiO2 reduction, preventing the formation of elemental Si, while O2 replenishes unsaturated bonds on the surface, reducing defects. S4 heat preservation annealing: After melting, maintain plasma power at 600W and microwave power at 150W, control the cooling rate at 9℃ / min, reduce from 1900℃ to 1200℃, and hold for 40min; after holding, turn off the microwave, reduce plasma power to 250W, and allow to cool naturally to 25℃ to obtain the finished quartz tube.

[0036] Example 6: A process for fusion of microwave and plasma into a quartz tube, comprising the following steps: S1 Quartz Raw Material Pretreatment: High-purity quartz sand (SiO2 purity ≥ 99.99%, particle size 50~100 μm) is soaked in a mixture of 1 mol / L hydrofluoric acid and 2 mol / L nitric acid for 20~30 min, where the volume ratio of hydrofluoric acid to nitric acid is 1:3, to remove surface metallic impurities. Then it is rinsed with deionized water until the pH value is 7, and dried at 80~100℃ for 2~3 h. Then it is pressed into a tubular blank (outer diameter 35 mm, inner diameter 20 mm, length 150 mm).

[0037] S2 Microwave Pretreatment: The tubular blank obtained in step S1 is placed in the center of a microwave resonant cavity with a frequency of 2.45 GHz, a microwave power of 800 W, and a treatment time of 12 min, under an argon atmosphere with a flow rate of 75 mL / min to activate Si-O bond vibrations. At this time, the internal temperature of the blank is ≤300℃, with no obvious heating, only molecular activation.

[0038] S3 Co-melting: The pretreated billet from steps S1 and S2 is transferred into a plasma torch, and a mixture of Ar and O2 gases is introduced, with a volume ratio of Ar to O2 of 9:1. The microwave power from step S2 is maintained, the plasma power is set to 2000W, the plasma working gas flow rate is 200mL / min, and the melting temperature is 1950℃. Melting is then carried out for 9 minutes. The activated Si-O bonds break rapidly in the plasma, forming molten SiO2. The Ar-O2 mixture inhibits SiO2 reduction, preventing the formation of elemental Si, while O2 replenishes unsaturated bonds on the surface, reducing defects. S4 heat preservation annealing: After melting, maintain plasma power at 600W and microwave power at 150W, control the cooling rate at 10℃ / min, reduce from 1950℃ to 1150℃, and hold for 45min; after holding, turn off the microwave, reduce plasma power to 250W, and allow to cool naturally to 25℃ to obtain the finished quartz tube.

[0039] Comparative Example 1: Quartz tubes were prepared by melting using conventional electric heating (Mo electrode).

[0040] Comparative Example 2: The S2 microwave pretreatment step was not performed, and the remaining steps and conditions were the same as in Example 5.

[0041] Comparative Example 3: The S3 co-melting was replaced with microwave heating melting alone, and the remaining steps and conditions were the same as in Example 5.

[0042] Comparative Example 4: The S3 co-melting was replaced with plasma heating melting, and the remaining steps and conditions were the same as in Example 5.

[0043] Comparative Example 5: In the S4 heat treatment annealing step, the temperature control and heat treatment step was not performed. Instead, the temperature was directly reduced from the melting temperature to 25°C. The remaining steps and conditions were the same as in Example 5.

[0044] The quartz tubes prepared in Examples 1-6 and Comparative Examples 1-5 were subjected to performance testing. The test data are shown in the table below:

[0045] The data in the table above shows that: 1. From the parameter changes in Examples 1 to 6 (microwave power 300→800W, plasma power 1000→2000W, Ar:O2=4:1→9:1, melting temperature 1700→1950℃), it can be seen that the performance follows a pattern of "gradual improvement → best in Example 5 → slight decline in Example 6". The main reasons are as follows: (1) Synergistic effect of microwave power: In Example 1 (300W), the microwave power was low, and the Si-O bond was not fully activated, requiring higher plasma energy compensation, resulting in an energy consumption of 6.2 kW·h / kg; In Example 5 (700W), the microwave power was moderate, and the Si-O bond was fully activated, forming a “vibration-pyrolysis” synergy with the high temperature of the plasma, reducing the energy consumption to 4.2 kW·h / kg; In Example 6 (800W), the microwave power was too high, and the Si-O bond in the billet vibrated excessively (microcracks appeared), requiring an extended melting time to fill the defects, and the energy consumption rose back to 4.5 kW·h / kg.

[0046] (2) The balancing effect of plasma parameters: In Example 1 (Ar:O2=4:1), the excess of O2 led to the oxidation and volatilization of some SiO2 (transmittance 86%); In Example 5 (Ar:O2=8:1), the O2 ratio was just right, which could both suppress the reduction of SiO2 (no Si elemental formation) and complete the surface unsaturated bonds (minimum defects), with a transmittance of 93% and a bubble rate of only 0.4%; In Example 6 (Ar:O2=9:1), the insufficient O2 increased the surface defects and the transmittance dropped to 92%.

[0047] (3) Matching effect of melting temperature and time: In Example 1 (1700℃ / 4min), the temperature was too low and the melting was insufficient (wall thickness deviation 0.18mm); In Example 5 (1900℃ / 8min), the temperature and time were matched, the melting was complete and there was no excessive volatilization (wall thickness deviation 0.09mm); In Example 6 (1950℃ / 9min), the temperature was too high, the volatilization of SiO2 increased (wall thickness deviation 0.10mm), and the bubble rate rose to 0.5%.

[0048] The parameter combination in Example 5 (microwave 700W, plasma 1800W, Ar:O2=8:1, 1900℃ / 8min) achieved optimal synergy between "microwave activation-plasma melting-heat preservation annealing", with all performance parameters reaching their best.

[0049] 2. By comparing Example 5 with Comparative Examples 1-5, it can be seen that: Example 5 compared to Comparative Example 1 (traditional electric heating): Example 5 showed a 52.3% reduction in unit energy consumption (4.2 kW·h / kg) compared to the traditional process (8.8 kW·h / kg), a 90.9% reduction in thermal field temperature difference (5°C) compared to the traditional process (55°C), a 98.9% reduction in metal residue (0.2 ppm) compared to the traditional process (18.5 ppm), a 13.4% increase in light transmittance (93%), and a 76.3% reduction in wall thickness deviation (0.09 mm). This demonstrates that the synergistic process solves the core defects of traditional electric heating, such as high energy consumption, uneven thermal field, and electrode contamination.

[0050] Example 5 compared to Comparative Example 2 (without microwave pretreatment): Without microwave pretreatment, the Si-O bonds were not activated, requiring higher plasma energy to melt. This resulted in Example 5 having a 39.1% lower energy consumption (4.2 kW·h / kg) compared to Comparative Example 2 (6.9 kW·h / kg), and a 77.3% lower thermal field temperature difference (5°C) compared to Comparative Example 2 (22°C). This demonstrates that "molecular activation" through microwave pretreatment is a crucial prerequisite for reducing energy consumption and improving thermal field uniformity.

[0051] Example 5 compared to Comparative Example 3 (microwave heating alone): Microwave heating alone can only soften the billet (≤500℃) and cannot break the Si-O bonds to achieve melting, proving that microwaves need to work in conjunction with plasma to be effective, and microwaves alone cannot meet the melting requirements.

[0052] Example 5 compared to Comparative Example 4 (plasma heating alone): Plasma heating alone, without microwave activation, resulted in a 42.5% reduction in energy consumption (4.2 kW·h / kg) compared to Comparative Example 4 (7.3 kW·h / kg), and an 82.1% reduction in thermal field temperature difference (5°C) compared to Comparative Example 4 (28°C). This demonstrates that plasma must be combined with microwaves to achieve "low-temperature rapid melting" and avoid the high energy consumption and uneven thermal field of heating alone.

[0053] Example 5 compared to Comparative Example 5 (annealing without heat preservation): In annealing without heat preservation, the rapid cooling of molten SiO2 easily generates internal stress, resulting in a 9.4% increase in light transmittance (93%) compared to Comparative Example 5 (85%), a 55% decrease in wall thickness deviation (0.09 mm) compared to Comparative Example 5 (0.20 mm), and a 69.2% decrease in bubble rate (0.4%) compared to Comparative Example 5 (1.3%). This demonstrates that heat preservation annealing is a necessary step to eliminate internal stress and improve molding accuracy and optical performance.

[0054] In summary, the microwave-plasma synergistic melting process, through the three-step synergy of "microwave molecular activation - plasma uniform thermal field - heat preservation annealing", can effectively reduce energy consumption, effectively control the temperature difference of the thermal field, increase light transmittance, and greatly reduce metal ion residue, finished product wall thickness deviation and bubble rate, thus significantly improving the performance of quartz tubes prepared by the process method provided by this invention.

[0055] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A process for the synergistic melting of quartz tubes using microwave and plasma, characterized in that, Includes the following steps: S1 Quartz Raw Material Pretreatment: Quartz sand is soaked in a mixture of hydrofluoric acid and nitric acid, then rinsed with deionized water and dried, and pressed into a tubular blank. S2 Microwave pretreatment: The tubular blank obtained in step S1 is placed in a 2.45GHz microwave resonant cavity, the microwave power is set, and it is treated in an inert gas atmosphere to activate the Si-O bond vibration. S3 Co-melting: The pre-treated billet after steps S1 and S2 is transferred into the plasma torch, a gas mixture of Ar and O2 is introduced, the microwave power of step S2 is maintained, the plasma power, plasma working gas flow rate and temperature are set, and then melting is carried out. S4 heat preservation annealing: Control the cooling rate to cool to 1150~1400℃, hold for 20~45min, and then cool to 25℃.

2. The process method for microwave and plasma synergistic melting of a quartz tube according to claim 1, characterized in that, In the S1 quartz raw material pretreatment step, the concentration of hydrofluoric acid is 0.5~1 mol / L.

3. The process method for microwave and plasma synergistic melting of a quartz tube according to claim 1, characterized in that, In the S1 quartz raw material pretreatment step, the concentration of nitric acid is 1~2 mol / L.

4. The process method for microwave and plasma synergistic melting of a quartz tube according to claim 1, characterized in that, In the S1 quartz raw material pretreatment step, the volume ratio of hydrofluoric acid to nitric acid is 1:

3.

5. The process method for microwave and plasma synergistic melting of a quartz tube according to claim 1, characterized in that, In the S2 microwave preprocessing step, the microwave power is 300~800W.

6. The process method for microwave and plasma synergistic melting of a quartz tube according to claim 1, characterized in that, In the S3 co-melting step, the volume ratio of Ar to O2 is (4~9):

1.

7. The process method for microwave and plasma synergistic melting of a quartz tube according to claim 1, characterized in that, In the S3 co-melting step, the plasma working gas flow rate is 100~200mL / min.

8. The process method for microwave and plasma synergistic melting of a quartz tube according to claim 1, characterized in that, In the S3 co-melting step, the plasma power is 1000~2000W.

9. The process method for microwave and plasma synergistic melting of a quartz tube according to claim 1, characterized in that, In the S3 co-melting step, the melting temperature is 1700~1950℃; the melting time is 4~9min.

10. The process method for microwave and plasma synergistic melting of a quartz tube according to claim 1, characterized in that, In the S4 heat treatment annealing step, the cooling rate is 5~10℃ / min.

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