Large-height-diameter-ratio quartz glass ingot trough sinking method

Abstract

The invention aims to provide a large height-diameter ratio quartz glass ingot trough sinking method which comprises the following steps: A, pretreating a quartz glass ingot to be subjected to trough sinking to obtain a pretreated quartz glass ingot; b, assembling the quartz glass ingot material into an anti-toppling mold, then putting the whole anti-toppling mold into a groove sinking furnace, heating to melt the quartz glass ingot material, carrying out uniform heat preservation to completely melt the quartz glass ingot material, and molding based on the anti-toppling mold; and C, cooling in three cooling intervals, cooling at a constant speed in each cooling interval, sequentially decreasing the cooling speeds of the three cooling intervals, and cooling in the last cooling interval to reach the room temperature, thereby obtaining the quartz glass blank with the large height-diameter ratio. According to the invention, the uniformity of the product is improved and the stress birefringence of the product is reduced by controlling the temperature in the processes of heating and melting, heat preservation and homogenization and cooling when the ingot trough sinks.

Description

Technical Field

[0001] The invention relates to the technical field of quartz glass manufacturing, in particular to a quartz glass ingot trough sinking method with a large aspect ratio. Background Art

[0002] Microelectronics, optoelectronics, aerospace, laser and precision optics and other high-tech industries are developing industries, which are the core and catalyst of many technical fields and industries. Ultraviolet optical quartz glass is its key basic material, supporting the development of these high-tech industries and has broad development prospects. Quartz glass is an irreplaceable high-purity basic material in national strategic industries and pillar industries.

[0003] There are different manufacturing processes for artificial synthetic quartz glass, and the production processes are different for different uses. The reaction mechanism of VAD synthetic quartz glass is also flame hydrolysis. The principle is to drive the volatile liquid silicon tetrachloride into the combustion gas of hydrogen / oxygen combustion under the drive of the carrier gas, react with water vapor to generate amorphous silicon dioxide, and deposit it on the high-temperature rotating target to form quartz glass. Its characteristics: high deposition efficiency and fast rate; low hydroxyl content; suitable for making long rod-shaped quartz glass ingots. However, VAD synthetic quartz glass is prone to defects such as stones and pores during polycondensation, so it is not suitable for making large-sized quartz glass. The size of VAD synthetic quartz glass is Φ150-Φ200mm. In order to obtain large-sized quartz glass products that meet the actual use requirements, VAD quartz ingots need to be troughed. After high-temperature melting, secondary molding is performed. And the optical uniformity and other properties of quartz glass are improved.

[0004] Secondary molding is to place the slender quartz ingot in a slot-sink high-temperature furnace, melt the quartz glass again by high temperature and pressure, and spread it in the mold of the graphite crucible to prepare a larger quartz blank. However, during the secondary molding of the slender quartz ingot, the ingot is unevenly heated locally due to the uneven temperature field in the high-temperature furnace, resulting in the ingot being unable to spread vertically downward and evenly around after melting. The ingot tilts and collapses. The product obtained after melting has defects such as uneven thickness and folding, which not only reduces the final product yield, but also seriously affects the product quality. Summary of the invention

[0005] The present invention aims to provide a method for trough settling of quartz glass ingots with a large aspect ratio. The method can solve the problem that the dumping of quartz glass ingots with a large aspect ratio affects the product quality when the ingots are trough settling. The method improves the uniformity of the product and reduces the stress birefringence of the product by controlling the temperature of the heating, melting, heat preservation, homogenization and cooling processes of the ingots during trough settling.

[0006] The method for sinking a quartz glass ingot with a large aspect ratio comprises the following steps: A. pre-treating the quartz glass ingot to be sunk in the tank to obtain a pre-treated quartz glass ingot; B. Assemble the quartz glass ingot into the anti-dumping mold, then place the anti-dumping mold as a whole in a trough sink furnace, heat up to melt the quartz glass ingot, keep it evenly to make it completely melted, and form it based on the anti-dumping mold; C. The temperature is cooled in three cooling intervals. The temperature is cooled at a uniform speed in each cooling interval. The cooling speeds of the three cooling intervals decrease in sequence. After the temperature is cooled in the last cooling interval, the temperature reaches room temperature, thereby obtaining a quartz glass blank with a large aspect ratio.

[0007] In the step A, the pretreatment comprises the following steps: The quartz glass ingot to be sump-sunk is immersed in an ultrasonic cleaning machine filled with pure water for ultrasonic cleaning for 40-100 minutes, then taken out and its surface is wiped with alcohol, then wrapped with a film for storage, and the film is removed before being loaded into the anti-dumping mold; the film is a PE film or a PVC film.

[0008] The anti-dumping mold comprises a base, a column, a guide support rod, a buckle cap, and a crucible side plate; The base is provided with more than three groups of columns at even intervals along the circumferential direction, and the upper part of the inner side surface of each column is provided with a guide groove along the vertical direction. The rear end of the guide support rod is installed in the guide groove through a slider and can slide along the guide groove; the buckle cap is a cylinder with a top seal, and the outer side surface of the cylinder is provided with mounting grooves corresponding to the front ends of each guide support rod. The front ends of the guide support rods extend toward the center of the base and are installed in the mounting grooves on the outer circumferential surface of the buckle cap; a distance is left between the inner side wall of the buckle cap and the side surface of the quartz glass column; The crucible side plate is a circular ring body, and the base is located on the inner side of each column and is provided with an annular groove corresponding to the crucible side plate. The lower end of the crucible side plate is inserted into the annular groove and assembled on the base. The crucible side plate and the base surrounded by it constitute a forming mold structure.

[0009] In the step B, when the quartz glass ingot is assembled into the anti-dumping mold, a graphite paper is placed on the top surface of the base surrounded by the side plates of the crucible, and a plurality of holes are evenly arranged on the graphite paper, with a hole diameter of 1-2 mm and a hole spacing of 3-7 mm; After the lower end of the crucible side plate is inserted into the annular groove, the gap between the lower end of the crucible side plate and the annular groove is filled with graphite paper.

[0010] Four groups of columns are evenly spaced along the circumferential direction on the base. After the guide support rods are installed, the angle between adjacent support rods is 90 degrees.

[0011] The buckle cap is a cylindrical body with a sealed top; the slider is a hemispherical structure.

[0012] The upper end of the guide groove is an opening, which is located on the top surface of the column, and the bottom surface of the guide groove is an inclined surface that tilts upward from the outside to the inside.

[0013] The length of the guide groove is 2 / 5-3 / 5 of the length of the column; the angle between the inclined plane and the horizontal plane is 45°-60°.

[0014] The installation groove is a threaded groove, and the front end of the guide support rod is provided with a thread, and is assembled in the installation groove through thread matching; The buckle cap, the column, the base, the crucible side plate and the sliding block are made of high-purity graphite, and the guide support rod is made of carbon fiber.

[0015] In the step B, when heating and melting, the tank sink furnace is kept in vacuum, the vacuum pressure is less than 5Pa, the heating rate is 5-10°C / min, and the final heating temperature is 1800°C-1900°C.

[0016] In the step B, when the temperature is kept uniform, nitrogen is added to a positive pressure of 0.01-0.1 MPa, and the temperature is controlled at 1700°C-1900°C.

[0017] In the step C, the three cooling intervals are: the insulation uniform temperature-1000°C interval, the cooling rate is 1.5-2.2°C / min; the 1000°C-500°C interval, the cooling rate is 1-1.5°C / min; the 500°C-room temperature interval, the cooling rate is 0.6-1°C / min.

[0018] The working principle of the anti-dumping mold of the present invention is as follows: As the temperature in the melting furnace increases, the viscosity of the quartz glass decreases, and the ingot gradually softens from the outside to the inside due to surface heat radiation, and spreads out evenly around. However, in practice, due to the difference in temperature field in the furnace, the ingot is heated unevenly, causing the ingot to soften locally first, and then tilt or even collapse after gravity imbalance. The anti-dumping mold is inserted into the buckle cap on the upper part of the long quartz ingot, and a certain pressure is applied to the ingot based on the buckle cap's own gravity, so that when it tilts, it can effectively ensure that the ingot spreads downward within the vertical range. The inner wall of the buckle cap is 10mm away from the ingot, which can effectively block the heat radiation and limit the heat on the upper part of the ingot, ensuring that the ingot gradually melts and spreads from bottom to top. When the buckle cap movable body is lowered to the limiting position, the ingot has softened to a low level and can be stably spread out to full position. In addition, the bottom surface of the limiting groove is designed as a slope, so that it has an inwardly inclined chamfer design, which can prevent graphite dust generated by the friction between the support rod and the column from falling into the crucible and prevent contamination after the ingot is melted.

[0019] The beneficial effects of the present invention are as follows: The present invention can meet the needs of the secondary molding groove sinking process of slender quartz glass ingots of different sizes, for example, diameters of Φ100-Φ200.

[0020] The invention has a simple structure, is easy to assemble, and is flexible in application. It can effectively control the tipping and deflection of a slender ingot. The device can be widely used in various quartz glass heat treatment molding manufacturing fields and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural elevation view of the anti-dumping mold of the embodiment; Figure 2 A top view of the anti-dumping mold of an embodiment; The serial numbers and names in the figure are as follows: 1-base, 2-column, 3-guide support rod, 4-buckle cap, 5-quartz glass column, 6-guide groove, 7-slider, 8-installation groove, 9-inclined surface, 10-crucible side plate, 11-ring groove. DETAILED DESCRIPTION

[0022] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0023] Examples 1-4 used Figure 1-2 The anti-dumping mold shown includes a base 1, a column 2, a guide support rod 3, a buckle cap 4, and a crucible side plate 10; The base 1 is provided with more than three groups of columns 2 at even intervals along the circumferential direction, and the upper part of the inner side surface of each column 2 is provided with a guide groove 6 in the vertical direction. The rear end of the guide support rod 3 is installed in the guide groove 6 through a slider 7 and can slide along the guide groove 6; the buckle cap 4 is a cylinder with a top seal, and the outer side surface of the cylinder is provided with a mounting groove 8 corresponding to the front end of each guide support rod 3. The front end of the guide support rod 3 extends toward the center of the base 1 and is installed in the mounting groove 8 on the outer circumferential surface of the buckle cap 4; there is a gap between the inner side wall of the buckle cap 4 and the side surface of the quartz glass column; The crucible side plate 10 is a circular ring body, and the base 1 is located on the inner side of each column 2 and is provided with an annular groove 11 corresponding to the crucible side plate 10. The lower end of the crucible side plate 10 is inserted into the annular groove 11 and assembled on the base 1. The crucible side plate 10 and the base 1 surrounded by it constitute a molding mold structure.

[0024] The base 1 is provided with four groups of upright posts 2 at even intervals along the circumferential direction. After the guide support rods 3 are installed, the angle between adjacent support rods 2 is 90°.

[0025] The buckle cap 4 is a cylindrical body with a sealed top; the slider 7 is a hemispherical structure.

[0026] The upper end of the guide groove 6 is an opening, and the opening is located on the top surface of the column 2. The bottom surface of the guide groove 6 is an inclined surface 9 that tilts upward from the outside to the inside.

[0027] The length of the guide groove 6 is 1 / 2 of the length of the column 2; the angle between the inclined surface 9 and the horizontal plane is 52°.

[0028] The installation groove 8 is a threaded groove, and the front end of the guide support rod 3 is provided with a thread, and is assembled with the installation groove 8 through thread matching; The buckle cap 4, the column 2, the base 1, the crucible side plate 10, and the sliding block 7 are made of high-purity graphite, and the guide support rod 3 is made of carbon fiber. Example 1

[0029] A method for sinking a quartz glass ingot with a large aspect ratio comprises the following steps: A. pre-treating the quartz glass ingot to be sunk in the tank to obtain a pre-treated quartz glass ingot; The preprocessing includes the following steps: The quartz glass ingot to be sump-sunk is immersed in an ultrasonic cleaning machine filled with pure water for ultrasonic cleaning for 40 minutes, then taken out and its surface is wiped with alcohol, and then wrapped with a film for storage, and the film is removed before being loaded into the anti-dumping mold; the film is a PE film or a PVC film.

[0030] B. Assemble the quartz glass ingot into the anti-dumping mold, and pad the top surface of the base 1 surrounded by the crucible side plate 10 with graphite paper, and evenly set a plurality of holes on the graphite paper, with a hole diameter of 1 mm and a hole spacing of 3 mm; after the lower end of the crucible side plate 10 is inserted into the annular groove 11, fill the gap between it and the annular groove 11 with graphite paper; The anti-dumping mold is placed in a tank sink furnace as a whole; the tank sink furnace is then controlled to be in a vacuum state, the vacuum pressure is 2Pa, the heating rate is 5°C / min, and the final temperature is 1800°C, so that the quartz glass ingot is melted; nitrogen is added to a positive pressure of 0.01Mpa, the temperature is controlled to 1700°C, and the temperature is evenly maintained to make it completely melted, and the anti-dumping mold is used for molding; C. The temperature is cooled in three cooling intervals. The temperature is cooled at a uniform speed in each cooling interval. The cooling speeds of the three cooling intervals decrease in sequence. After the temperature is cooled in the last cooling interval, the temperature reaches room temperature, thereby obtaining a quartz glass blank with a large aspect ratio.

[0031] In the step C, the three cooling intervals are: 1700-1000°C interval, cooling rate 1.5°C / min; 1000°C-500°C interval, cooling rate 1°C / min; 500°C-room temperature interval, cooling rate 0.6°C / min. Example 2

[0032] A method for sinking a quartz glass ingot with a large aspect ratio comprises the following steps: A. pre-treating the quartz glass ingot to be sunk in the tank to obtain a pre-treated quartz glass ingot; The preprocessing includes the following steps: The quartz glass ingot to be sump-sunk is immersed in an ultrasonic cleaning machine filled with pure water for ultrasonic cleaning for 100 minutes, then taken out and its surface is wiped with alcohol, and then wrapped with a film for storage, and the film is removed before being loaded into the anti-dumping mold; the film is a PE film or a PVC film.

[0033] B. Assemble the quartz glass ingot into the anti-dumping mold, and pad the top surface of the base 1 surrounded by the crucible side plate 10 with graphite paper, and evenly set a plurality of holes on the graphite paper, with a hole diameter of 2 mm and a hole spacing of 7 mm; after the lower end of the crucible side plate 10 is inserted into the annular groove 11, fill the gap between it and the annular groove 11 with graphite paper; The anti-dumping mold is placed in a tank sink furnace as a whole; the tank sink furnace is then controlled to be in a vacuum state, the vacuum pressure is 5Pa, the heating rate is 10°C / min, and the final heating temperature is 1900°C, so that the quartz glass ingot is melted; nitrogen is added to a positive pressure of 0.1Mpa, the temperature is controlled to 1900°C, and the temperature is evenly maintained to make it completely melted, and the anti-dumping mold is used for molding; C. The temperature is cooled in three cooling intervals. The temperature is cooled at a uniform speed in each cooling interval. The cooling speeds of the three cooling intervals decrease in sequence. After the temperature is cooled in the last cooling interval, the temperature reaches room temperature, thereby obtaining a quartz glass blank with a large aspect ratio.

[0034] In the step C, the three cooling intervals are: 1900-1000°C interval, cooling rate 2.2°C / min; 1000°C-500°C interval, cooling rate 1.5°C / min; 500°C-room temperature interval, cooling rate 1°C / min. Example 3

[0035] A method for sinking a quartz glass ingot with a large aspect ratio comprises the following steps: A. pre-treating the quartz glass ingot to be sunk in the tank to obtain a pre-treated quartz glass ingot; The preprocessing includes the following steps: The quartz glass ingot to be sump-sunk is immersed in an ultrasonic cleaning machine filled with pure water for ultrasonic cleaning for 60 minutes, then taken out and its surface is wiped with alcohol, and then wrapped with a film for storage, and the film is removed before being loaded into the anti-dumping mold; the film is a PE film or a PVC film.

[0036] B. Assemble the quartz glass ingot into the anti-dumping mold, and pad the top surface of the base 1 surrounded by the crucible side plate 10 with graphite paper, and evenly set a plurality of holes on the graphite paper, with a hole diameter of 1.5 mm and a hole spacing of 5 mm; after the lower end of the crucible side plate 10 is inserted into the annular groove 11, fill the gap between it and the annular groove 11 with graphite paper; The anti-dumping mold is placed in a tank sink furnace as a whole; the tank sink furnace is then controlled to be in a vacuum state, the vacuum pressure is 3Pa, the heating rate is 7°C / min, and the final heating temperature is 1850°C, so that the quartz glass ingot is melted; nitrogen is added to a positive pressure of 0.05Mpa, the temperature is controlled to 1800°C, and the temperature is evenly maintained to make it completely melted, and the anti-dumping mold is formed; C. The temperature is cooled in three cooling intervals. The temperature is cooled at a uniform speed in each cooling interval. The cooling speeds of the three cooling intervals decrease in sequence. After the temperature is cooled in the last cooling interval, the temperature reaches room temperature, thereby obtaining a quartz glass blank with a large aspect ratio.

[0037] In the step C, the three cooling intervals are: 1800-1000°C interval, cooling rate 2°C / min; 1000°C-500°C interval, cooling rate 1.2°C / min; 500°C-room temperature interval, cooling rate 0.8°C / min. Example 4

[0038] A method for sinking a quartz glass ingot with a large aspect ratio comprises the following steps: A. pre-treating the quartz glass ingot to be sunk in the tank to obtain a pre-treated quartz glass ingot; The preprocessing includes the following steps: The quartz glass ingot to be sump-sunk is immersed in an ultrasonic cleaning machine filled with pure water for ultrasonic cleaning for 70 minutes, then taken out and its surface is wiped with alcohol, and then wrapped with a film for storage, and the film is removed before being loaded into the anti-dumping mold; the film is a PE film or a PVC film.

[0039] B. Assemble the quartz glass ingot into the anti-dumping mold, and pad the top surface of the base 1 surrounded by the crucible side plate 10 with graphite paper, and evenly set a plurality of holes on the graphite paper, with a hole diameter of 1.3 mm and a hole spacing of 4 mm; after the lower end of the crucible side plate 10 is inserted into the annular groove 11, fill the gap between it and the annular groove 11 with graphite paper; The anti-dumping mold is placed in a tank sink furnace as a whole; the tank sink furnace is then controlled to be in a vacuum state, the vacuum pressure is 4Pa, the heating rate is 8°C / min, and the final temperature is 1880°C, so that the quartz glass ingot is melted; nitrogen is added to a positive pressure of 0.07Mpa, the temperature is controlled to 1760°C, and the temperature is evenly maintained to make it completely melted, and the anti-dumping mold is formed; C. The temperature is cooled in three cooling intervals. The temperature is cooled at a uniform speed in each cooling interval. The cooling speeds of the three cooling intervals decrease in sequence. After the temperature is cooled in the last cooling interval, the temperature reaches room temperature, thereby obtaining a quartz glass blank with a large aspect ratio.

[0040] In the step C, the three cooling intervals are: 1760-1000°C interval, cooling rate 1.8°C / min; 1000°C-500°C interval, cooling rate 1.1°C / min; 500°C-room temperature interval, cooling rate 0.7°C / min.

Claims

1. A method for sinking a quartz glass ingot with a large aspect ratio, characterized in that: The following steps are involved: A. pre-treating the quartz glass ingot to be sunk in the tank to obtain a pre-treated quartz glass ingot; B. Assemble the quartz glass ingot into the anti-dumping mold, then place the anti-dumping mold as a whole in a trough sink furnace, heat up to melt the quartz glass ingot, keep it evenly to make it completely melted, and form it based on the anti-dumping mold; C. The temperature is cooled in three cooling intervals. The temperature is cooled at a uniform speed in each cooling interval. The cooling speeds of the three cooling intervals decrease in sequence. After the temperature is cooled in the last cooling interval, the temperature reaches room temperature, thereby obtaining a quartz glass blank with a large aspect ratio.

2. The method for sinking a quartz glass ingot having a large aspect ratio as claimed in claim 1, characterized in that: In the step A, the pretreatment comprises the following steps: The quartz glass ingot to be sump-sunk is immersed in an ultrasonic cleaning machine filled with pure water for ultrasonic cleaning for 40-100 minutes, then taken out and its surface is wiped with alcohol, then wrapped with a film for storage, and the film is removed before being loaded into the anti-dumping mold; the film is a PE film or a PVC film.

3. The method for sinking a quartz glass ingot having a large aspect ratio as claimed in claim 1, characterized in that: The anti-dumping mold comprises a base (1), a column (2), a guide support rod (3), a buckle cap (4), and a crucible side plate (10); The base (1) is provided with more than three groups of columns (2) at even intervals in the circumferential direction, and the upper part of the inner side surface of each column (2) is provided with a guide groove (6) in the vertical direction. The rear end of the guide support rod (3) is installed in the guide groove (6) through a slider (7) and can slide along the guide groove (6); the buckle cap (4) is a cylinder with a top seal, and the outer side surface of the cylinder is provided with a mounting groove (8) corresponding to the front end of each guide support rod (3), and the front end of the guide support rod (3) extends toward the center of the base (1) and is installed in the mounting groove (8) on the outer circumferential surface of the buckle cap (4); a distance is left between the inner side wall of the buckle cap (4) and the side surface of the quartz glass column; The crucible side plate (10) is a circular ring body, and the base (1) is located on the inner side of each column (2) and is provided with an annular groove (11) corresponding to the crucible side plate (10). The lower end of the crucible side plate (10) is inserted into the annular groove (11) and assembled on the base (1). The crucible side plate (10) and the base (1) surrounded by it constitute a molding mold structure; Preferably, four groups of uprights (2) are evenly spaced along the circumferential direction on the base (1), and after the guide support rods (3) are installed, the angle between adjacent support rods (2) is 90°.

4. The method for sinking a quartz glass ingot having a large aspect ratio as claimed in claim 3, characterized in that: In the step B, when the quartz glass ingot is assembled into the anti-dumping mold, a graphite paper is placed on the top surface of the base (1) surrounded by the crucible side plate (10), and a plurality of holes are evenly arranged on the graphite paper, with a hole diameter of 1-2 mm and a hole spacing of 3-7 mm; After the lower end of the crucible side plate (10) is inserted into the annular groove (11), the gap between the lower end of the crucible side plate (10) and the annular groove (11) is filled with graphite paper.

5. The method for sinking a quartz glass ingot having a large aspect ratio as claimed in claim 3, characterized in that: The buckle cap (4) is a cylindrical body with a sealed top; the slider (7) is a hemispherical structure.

6. The method for sinking a quartz glass ingot having a large aspect ratio as claimed in claim 3, characterized in that: The upper end of the guide groove (6) is an opening, and the opening is located on the top surface of the column (2). The bottom surface of the guide groove (6) is an inclined surface (9) that tilts upward from the outside to the inside. Preferably, the length of the guide groove (6) is 2 / 5-3 / 5 of the length of the column (2); and the angle between the inclined surface (9) and the horizontal plane is 45°-60°.

7. The method for sinking a quartz glass ingot having a large aspect ratio as claimed in claim 3, characterized in that: The installation groove (8) is a threaded groove, and the front end of the guide support rod (3) is provided with a thread, and is assembled with the installation groove (8) through thread matching; The buckle cap (4), the column (2), the base (1), the crucible side plate (10), and the slider (7) are made of high-purity graphite, and the guide support rod (3) is made of carbon fiber.

8. The method for sinking a quartz glass ingot having a large aspect ratio as claimed in claim 1, characterized in that: In the step B, when heating and melting, the tank sink furnace is kept in vacuum, the vacuum pressure is less than 5Pa, the heating rate is 5-10°C / min, and the final heating temperature is 1800°C-1900°C.

9. The method for sinking a quartz glass ingot having a large aspect ratio as claimed in claim 1, characterized in that: In the step B, when the temperature is kept uniform, nitrogen is added to a positive pressure of 0.01-0.1 MPa, and the temperature is controlled at 1700°C-1900°C.

10. The method for sinking a quartz glass ingot having a large aspect ratio according to claim 1, wherein: In the step C, the three cooling intervals are: the insulation uniform temperature-1000°C interval, the cooling rate is 1.5-2.2°C / min; the 1000°C-500°C interval, the cooling rate is 1-1.5°C / min; the 500°C-room temperature interval, the cooling rate is 0.6-1°C / min.

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