Quartz glass deposition furnace as well as furnace top blowtorch assembly and control method thereof

Abstract

The invention provides a quartz glass deposition furnace and a furnace top blow lamp assembly and a control method thereof. The furnace top burner assembly of the quartz glass deposition furnace comprises linear rails fixed to a furnace top body and main blowtorches, two or more linear rails are fixed to the bottom end face of the furnace top body in the outward emitting direction from the circle center of the furnace top body, and each linear rail is provided with one main blowtorch capable of sliding relative to the linear rail. The main blowtorch is used for jetting silicon-containing substances and heating, a circle is drawn by taking the distance between the center of the main blowtorch and the circle center of the furnace top body as the radius and taking the circle center of the furnace top body, one or two or more virtual circles are formed, and when the number of the formed virtual circles is greater than or equal to 2, the two or more virtual circles are non-uniformly arranged at intervals so as to avoid the ripple defect. According to the quartz glass deposition furnace, the main blowtorch can move relative to the linear track, so that quartz glass of various sizes can be prepared by the hearth of the same size. And meanwhile, the manufacturing of the quartz glass ingot with better performance and higher light uniformity is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quartz glass preparation, and particularly relates to a quartz glass deposition furnace, a furnace top torch assembly thereof and a control method. BACKGROUND

[0002] Chemical vapor deposition (CVD) process is a key technology for synthesizing quartz glass production. By introducing the vaporized organosilicon compounds or inorganic silicon compounds, including but not limited to silicon tetrachloride, D4, etc. into the hydrogen-oxygen flame or the hydrocarbon compound flame such as methane, acetylene, etc. for high temperature hydrolysis, SiO2 particles are generated and deposited on the high temperature target to form fused quartz glass. The process gradually solidifies as the temperature decreases and finally forms synthetic quartz glass.

[0003] Synthetic quartz glass has important applications in high-tech fields due to its unique physical and chemical properties. Its microstructure is a network of tetrahedrons composed of ordered Si-O bonds, and in the macroscopic view, countless network tetrahedrons are arranged in disorder. This special structure endows the material with high melting point, strong radiation resistance, stable chemical properties, excellent spectral transmittance and low thermal expansion coefficient, etc. and is suitable for optical devices, semiconductors and aerospace technology and many other fields.

[0004] However, the structural uniformity of synthetic quartz glass is affected by many factors, including the change of the furnace atmosphere, the consistency of the deposition surface temperature, the distribution of the silicon-oxygen bond angle, the content and distribution of hydroxyl groups, and the accuracy of process control. These factors have a direct impact on the optical performance of the quartz glass. For example, the accurate control of the hydroxyl content is crucial to avoid light absorption and scattering; the uniformity of quartz glass doping, including but not limited to titanium, lead, phosphorus and other metal and non-metal elements, also has a great impact on the performance of the finished crystal ingot.

[0005] In the process of preparing large-size synthetic quartz glass by the existing chemical vapor deposition (CVD) technology, there are several limitations. The existing technology often uses multiple torch heating crucible deposition method in the furnace. In order to compensate for the uniformity of the deposition thickness in the radial direction, a certain number of torches are arranged on multiple straight track circles with different radii. At the same time, due to the difference in the linear speed of each torch, it may also lead to uneven distribution of glass surface temperature, affecting the optical uniformity of the quartz glass. In addition, the exchange of gas inside and outside the furnace may cause the furnace atmosphere to change constantly, further damaging the optical uniformity of the quartz glass.

[0006] The patent CN118993508A proposes a deposition furnace for manufacturing large-size high-uniformity synthetic quartz glass and a preparation method thereof. The scheme realizes uniform deposition of SiO2 particles by designing a specific arrangement of combined burners, and clearly defines the dynamic relationship between the number of torches and the radius of the straight track, thereby improving the influence of linear velocity on deposition uniformity. However, the installation position of the torches is not accurately calculated, resulting in the accumulation of deposition products from different straight track circles on the plane, mutual interference, and the formation of obvious high-low ripples, which greatly affects the optical uniformity of the final product. Moreover, a set of arrangement can only produce quartz ingots of a fixed size, which is not conducive to flexible planning of production efficiency and product quality according to demand. Therefore, it is necessary to provide an improved CVD deposition furnace structure to solve the limitations of the prior art and optimize the internal structure and optical performance of synthetic quartz glass and improve production efficiency. SUMMARY

[0007] The main purpose of the present application is to provide a quartz glass deposition furnace, its furnace top torch assembly and control method, aiming to produce quartz glass of different sizes with the same equipment without reducing the quality of the finished product.

[0008] To achieve the above-mentioned purpose, the present application provides a quartz glass deposition furnace furnace top burner assembly, comprising a straight track fixed on the furnace top body and a main torch, wherein, The bottom end face of the furnace top body is fixed with two or more straight tracks outward from the center of the circle, and the main torch is installed on each straight track and can slide relative to it. The main torch is used for spraying silicon-containing substances and heating. The center of the main torch to the distance from the center of the furnace top body is taken as the radius to draw a circle with the center of the furnace top body, forming one or two or more virtual circles. When the number of virtual circles formed is greater than or equal to 2, two or more virtual circles are arranged non-uniformly to avoid ripple defects.

[0009] Preferably, the straight track is also slidably connected with an auxiliary torch for heating.

[0010] Preferably, when the number of virtual circles formed is greater than or equal to 2, the distance between adjacent virtual circles gradually decreases in the direction from the outside to the inside along the straight track.

[0011] Preferably, when the number of virtual circles formed is greater than or equal to 2, the radius of the virtual circle is calculated by the function f(x), the radius X1=f(1) of the main torch on the first virtual circle on the innermost side, and the radius Xn=f(n) of the main torch on the outermost side. M=f (M), f (x) is a function related to the number of virtual circles required to produce quartz glass product crystal ingot finished product, and f (x) is a function with first derivative greater than 0 and second derivative less than 0, the domain x is any positive integer between 1 and M, M is the number of virtual circles, and N is the number of straight line tracks.

[0012] Preferably, when the diameter of the quartz glass product crystal ingot finished product required to be produced is less than 1000mm, the radius of the virtual circle is determined by the following formula: f (x) ; Wherein, r is the radius of the outermost virtual circle, C is a coefficient.

[0013] Preferably, when the diameter of the quartz glass product crystal ingot finished product required to be produced is greater than or equal to 1000mm, the radius of the virtual circle is determined by the following formula: f (x) = , Wherein, r is the radius of the outermost virtual circle, and r, C are coefficients.

[0014] Preferably, a plurality of said straight line tracks are uniformly arranged in the circumferential direction of the furnace top body.

[0015] Preferably, said auxiliary torch is outside the main torch.

[0016] The application also proposes a quartz glass deposition furnace, comprising a furnace body, a crucible, an exhaust pipe, an air inlet pipe and a rotating lifting device, the furnace body comprises a furnace top, a furnace wall and a furnace bottom, and the furnace top is provided with the quartz glass deposition furnace top burner assembly described above.

[0017] The application also proposes a control method based on the above-mentioned quartz glass deposition furnace, comprising the following steps: According to the diameter of the quartz glass product crystal ingot finished product required to be produced, determine how many virtual circles are to be arranged in the furnace top burner assembly, and determine the positions of each main torch and auxiliary torch; In the preheating stage and the material deposition stage of the deposition process, control the main torch and the auxiliary torch to be fixed; In the material stopping and preheating stage of the deposition process, control the main torch to be fixed, and control the auxiliary torch to move on the straight line track.

[0018] Preferably, after the deposition is stopped, control the main torch to move to the end face of the straight line track closest to the center of the furnace top body, and control the auxiliary torch to reciprocate outside the main torch to perform annealing treatment on the crystal ingot.

[0019] The quartz glass deposition furnace proposed by the application has the following beneficial effects: 1. By setting the main torch movable relative to the straight track, thus, the same size furnace can be used to produce a variety of sizes of quartz glass. In the case of the same number of torches, the larger the quartz glass ingot produced, the more uneven the heat mass distribution, and the poorer the product quality. However, the deposition furnace size is determined, and the quartz glass manufacturing level is also determined due to the fixed arrangement of the torches. If the product size requirement is not high but the quality requirement is high, since the main torch in the deposition furnace can move freely along the straight track, by placing a crucible of appropriate size and calculating the appropriate torch arrangement distance, the deposition range can be changed, and deposition can be carried out in a smaller range with the same number of torches, which is beneficial to the manufacture of quartz glass ingots with better performance and higher light uniformity. If the product light uniformity requirement is not high, but the size requirement is high, the torch arrangement can also be changed, and the crucible can be replaced to manufacture larger quartz glass ingots without the need to build a new deposition furnace, saving investment; 2. Because in the deposition furnace, SiO2 particles generated by the reaction gather, settle and eventually form molten quartz in the crucible. In this application, when the number of virtual circles formed is greater than or equal to 2, the two or more virtual circles are arranged non-uniformly to avoid ripple defects. This design avoids the local accumulation caused by arranging multiple torches on the same virtual circle, and also avoids the obvious division of the torch arrangement (division into rings), which leads to visible circular rings in the transition area between different rings distributed throughout the finished product crystal ingot, which is beneficial to the production of quartz glass ingots with higher optical uniformity; 4. By moving the main torch and the auxiliary torch, the distribution of hydroxyl groups in the quartz glass ingot can be improved. In a conventional deposition furnace, the deposition surface temperature gradually decreases outward along the radius direction during deposition, so the hydroxyl content changes from high to low along the radius direction. The present application can adjust the high temperature zone range and temperature during the deposition process by moving the main torch, change the diffusion law of hydrogen element, and thus make the temperature during the deposition process and the hydroxyl group after the deposition process uniformly distributed in the whole deposition surface range, thereby improving the optical and other physical properties; 5. Since the main torch and the auxiliary torch can move on the straight track, the movement has a cleaning effect on the lower side of the straight track (inside the furnace). During normal deposition, by moving briefly on the track and then resetting, the accumulation of smoke and dust on the straight track or at the torch outlet during the deposition process can be avoided, thereby avoiding the formation of large particles falling into the crucible and reducing the probability of air bubbles in the quartz. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a structure schematic view of the quartz glass deposition furnace embodiment 1 of the present application; Figure 2 is a structure schematic view of the furnace top burner in the quartz glass deposition furnace embodiment 1 of the present application; Figure 3A deposition amount and temperature thermal map of the quartz glass deposition furnace of the present application in Example 1; Figure 4 A structural schematic diagram of the furnace top burner of the quartz glass deposition furnace of the present application in Comparative Example 1; Figure 5 A deposition amount and temperature thermal map of the quartz glass deposition furnace of the present application in Comparative Example 1; Figure 6 A structural schematic diagram of the furnace top burner of the quartz glass deposition furnace of the present application in Example 2; Figure 7 A deposition amount and temperature thermal map of the quartz glass deposition furnace of the present application in Example 2; Figure 8 A structural schematic diagram of the furnace top burner of the quartz glass deposition furnace of the present application in Example 3; Figure 9 A structural schematic diagram of the furnace top burner of the quartz glass deposition furnace of the present application in Example 3; Figure 10 A structural schematic diagram of the furnace top burner of the quartz glass deposition furnace of the present application in Example 3; Figure 11 A moving track diagram of the auxiliary torch of the quartz glass deposition furnace control method of the present application in Example 1.

[0021] In the figure, 1-furnace top, 2-furnace wall, 3-furnace bottom, 4-torch group, 41-main torch, 42-auxiliary torch, 43-regular torch, 5-exhaust pipe, 6-rotary lifting device, 7-crucible, 8-crucible deposition surface, 9-furnace body top opening, 10-straight track.

[0022] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0023] It should be understood that the specific embodiments described herein merely exemplify the present application and are not intended to limit the present application.

[0024] It should be noted that in the description of the present application, the terms "transverse", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0025] The application provides a quartz glass deposition furnace.

[0026] The quartz glass deposition furnace comprises a furnace body, a crucible 7, an exhaust pipe 5, an air inlet pipe and a rotary lifting device 6, wherein the furnace body comprises a furnace top 1, a furnace wall 2 and a furnace bottom 3, the quartz glass deposition furnace top burner assembly is arranged on the furnace top 1, the crucible 7 is arranged on the furnace bottom 3, the rotary lifting device 6 vertically extends into the furnace body from the furnace bottom and is fixedly connected with the crucible 7, the rotary lifting device 6 can rotate around the central axis and can ascend and descend along the central axis, and the rotating speed and the ascending and descending speed can be adjusted. The quartz glass deposition furnace top burner assembly comprises straight rails 10 fixed on the furnace top 1 body and main torches 41, the bottom end surface of the furnace top 1 body is fixed with two or more straight rails 10 which are emitted outward from the center of the furnace top 1 body, each straight rail 10 is provided with a main torch 41 which can slide relative to the straight rail 10, the main torch 41 is used for spraying silicon-containing substances and heating, the distance from the center of the main torch 41 to the center of the furnace top 1 body is taken as the radius to draw a circle, one or two or more virtual circles are formed, and when the number of the virtual circles is greater than or equal to two, the two or more virtual circles are arranged at intervals in a non-uniform manner to avoid ripple defects.

[0027] The crucible 7 is composed of multiple refractory bricks with different sizes and a fixed-size base, and according to the size requirement of the target product, appropriate sizes are selected to combine into circular crucibles with different inner diameters, and the crucible is internally padded with quartz sand or quartz glass pieces as a deposition surface for depositing quartz glass.

[0028] Specifically, the main torch 41 and the straight rail 10 adopt a sliding rail mode, but are not limited to the sliding rail mode, and the main torch 41 can freely move along the radial direction on the straight rail 10 and can be fixed at a point to stably operate.

[0029] When the number of the virtual circles is greater than or equal to two, the radius of the virtual circle is calculated through a function f(x), the radius X1=f(1) of the main torch 41 on the first virtual circle on the innermost side, and the radius X M =f(M) of the main torch 41 on the outermost side, f(x) is a function related to the number of the virtual circles and the quartz glass product ingot finished product to be produced, f(x) is a function with a first derivative greater than 0 and a second derivative less than 0, the domain x is any positive integer between 1 and M, M is the number of the virtual circles, and N is the number of the straight rails 10.

[0030] Specifically, when the number of the formed virtual circles is greater than or equal to 2, the distance between adjacent virtual circles gradually decreases along the straight track 10 from outside to inside. That is, f(M+1)-f(M) < f(M)-f(M-1).

[0031] With this gradually decreasing arrangement, that is, the gradually dense arrangement of the main torches 41, this design avoids the local accumulation of large thickness caused by arranging multiple torches on the same virtual circle, and avoids the obvious zoning (zoning) of the torch arrangement, which causes the transition area between different rings distributed in the entire finished product quartz glass ingot to have a visible circular ring that affects the quality, and is beneficial to produce quartz glass ingots with higher optical uniformity.

[0032] In this embodiment, when the finished product quartz glass product ingot to be produced has a diameter less than 1000 mm, the radius of the virtual circle is determined by the following formula: f(x) ; (1) wherein, R is the radius of the outermost virtual circle, r and C are coefficients.

[0033] According to formula (1), the diameter relationship of the multiple virtual circles on the inside relative to the outermost virtual circle can be obtained. Formula (1) is suitable for the scene of linearly regulating the deposition rate at different radial positions.

[0034] Taking N as 6 and M as 2 as an example, that is, there are 6 straight tracks 10, and each straight track 10 has a main torch 41 slidingly installed thereon (the number of main torches 41 can also be greater than 6), at this time, there are 6 main torches 41, and the arrangement of the 6 main torches 41 forms two virtual circles. The diameter of the virtual circle on the inside can be obtained by substituting x=1 into the above formula (1). The coefficient r=6 can be set, and by substituting it into the formula, the relationship between f(1) and R can be obtained, and f(2)=R, that is, the radius of the outermost virtual circle is R.

[0035] When the finished product quartz glass product ingot to be produced has a diameter greater than or equal to 1000 mm, the radius of the virtual circle is determined by the following formula: f(x)= , (2) wherein, R is the radius of the outermost virtual circle, and r and C are coefficients.

[0036] The peripheral torch arrangement of this formula (2) is more dense than the torch arrangement calculated by formula (1), which can compensate for the edge temperature decay under large size.

[0037] Further, the plurality of straight tracks 10 are arranged uniformly in the circumferential direction of the furnace top 1 body. That is, the furnace top is uniformly arranged with N straight tracks 10 along the circumferential direction, and the straight tracks 10 at least include a first straight track 10, a second straight track 10 and a third straight track 10 arranged in sequence, and up to an Nth straight track 10. At this time, the plurality of straight tracks 10 exist with a fixed interval angle θ in the circumferential direction, and the interval angle is related to the number of straight tracks 10, and the interval angle θ = 360 / N.

[0038] Further, the straight track 10 is also slidably connected with an auxiliary burner 42 for heating. The main burner 41 sprays silicon-containing substances and heats. The auxiliary burner 42 does not spray silicon-containing substances, and is only a burner for providing heat.

[0039] Because of the existence of the movable auxiliary burner 42, in the cooling stage after deposition is completed, stress unevenness caused by fast peripheral cooling and slow internal cooling can be avoided. After the main burner 41 stops spraying material, it can be concentrated at the center of the furnace top; the auxiliary burner 42 continues to burn, while slowly moving back and forth along the radial direction, and gradually reducing the moving range, to ensure the uniformity of the overall cooling, which can effectively reduce the internal stress of the glass, reduce the cracks, stripes and bubbles on the edges of the finished quartz glass ingot.

[0040] The auxiliary burner 42 can be arranged at the periphery of the crucible 7 of different sizes at the same radius, to freely control the size of the high-temperature area, for ensuring the stability of the temperature environment of the deposition core area in the furnace when the size of the crucible 7 changes; or can be arranged inside the crucible 7 at different radii, to compensate for the local low temperature caused by the circumferential uneven arrangement of the main burner 41.

[0041] When the finished quartz glass product ingot diameter D required to be produced is D and the unit is millimeter, the number of virtual circles is greater than D / 100.

[0042] For example, when D is 1000, that is, when the finished quartz glass product ingot diameter required to be produced is 1000 millimeters, the number of virtual circles is greater than 10, at this time, the effect of avoiding ripple defects is best.

[0043] The quartz glass deposition furnace provided by the present application has the following beneficial effects: 1、By setting the main torch 41 movable relative to the straight track 10, thus, the same size furnace can be used to produce a variety of sizes of quartz glass. In the case of the same number of torches, the larger the quartz glass ingot produced, the more uneven the heat mass distribution, and the worse the product quality. Generally, after the size of the deposition furnace is determined, the torch arrangement is fixed, and the level of quartz glass manufacturing is also determined. If the product size requirement is not high but the quality requirement is high, since the main torch 41 in the present deposition furnace can move freely along the straight track 10, by placing a crucible 7 of appropriate size, calculating the appropriate torch arrangement distance, the deposition range can be changed, and deposition can be carried out in a smaller range with the same number of torches, which is beneficial to the manufacture of quartz glass ingots with better performance and higher light uniformity. If the product light uniformity requirement is not high, but the size requirement is high, the torch arrangement can also be changed, and the crucible 7 can be replaced, to manufacture a larger size quartz glass ingot, without the need to build a new deposition furnace, saving investment; 2、Because in the deposition furnace, SiO2 particles generated by the reaction gather, settle and eventually form molten quartz in the crucible 7. In the present application, when the number of virtual circles formed is greater than or equal to 2, the two or more virtual circles are arranged non-uniformly to avoid ripple defects. This design avoids the local accumulation of thickness caused by arranging multiple torches on the same virtual circle, and also avoids the obvious division of the torch arrangement into zones (rings), which causes visible circular rings in the transition area between different rings distributed throughout the finished product ingot range, affecting the quality. This is beneficial to the production of quartz glass ingots with higher optical uniformity; 4、By cooperating the movable main torch 41 and the auxiliary torch 42, the distribution of hydroxyl in the quartz glass ingot can be improved. Because in the ordinary deposition furnace, the deposition surface temperature gradually decreases outward along the radial direction during deposition, the hydroxyl content changes from high to low along the radial direction. The present application can adjust the high temperature zone range and temperature during the deposition process by moving the main torch 41, change the diffusion rule of hydrogen element, so that the temperature during the deposition process and the hydroxyl after the deposition is finished are uniformly distributed in the whole deposition surface range, thereby improving the optical and other physical properties; 5、Since the main torch 41 and the auxiliary torch 42 can move on the straight track 10, the movement has a cleaning effect on the lower side of the straight track 10 (inside the furnace). During normal deposition process, by moving temporarily on the track and then resetting, the accumulation of smoke and dust on the straight track 10 or at the torch outlet during the deposition process can be avoided, thereby avoiding the formation of large particles falling into the inside of the crucible 7, and reducing the probability of bubbles appearing in the quartz.

[0044] The following examples specifically illustrate the present quartz glass deposition furnace.

[0045] Example 1 In this example, the structure of the deposition furnace is as shown in Figure 1 , and the burner arrangement of the furnace top 1 is as shown in Figure 2In the embodiment, the auxiliary torch 42 is not arranged.

[0046] The deposition furnace provided in the embodiment includes a furnace body including a furnace top 1, a furnace wall 2 and a furnace bottom 3. A torch group 4 is arranged on the furnace top 1, which is used to generate heat and water by burning hydrogen-oxygen mixture and to generate SiO2 particles by reacting with raw materials. Exhaust pipes 5 are symmetrically arranged on the side of the furnace wall 2 and communicate with the inside of the furnace body. The exhaust pipes 5 are arranged 250-450 mm below the deposition surface. A rotary lifting device 6 is connected with the furnace bottom 3 and can drive the crucible 7 to rotate around the central axis at an adjustable speed. The deposition surface 8 of the crucible has a diameter of 800 mm and is arranged on the upper end of the rotary lifting device 6, which is used to collect the fused quartz particles. The top of the furnace body is provided with an opening 9 for monitoring the temperature distribution in the furnace.

[0047] One main torch 41 is arranged on each straight track 10. The main torch 41 is arranged according to the above formula (1), i.e. f(x) = 0.5x2- 100x + 5000. As shown in the arrangement shown in Figure 2 During the deposition process, the main torch 41 is fixed on the straight track 10 and does not move. The deposition amount and temperature thermal map are shown in Figure 3 .

[0048] According to the above method, a large-size synthetic quartz glass ingot with a diameter of 800 mm and a thickness of 300 mm is prepared by depositing for 48 hours. The quartz glass ingot obtained above is subjected to processing such as rounding, milling, polishing and the like. The edge of the round crystal ingot is uniform in light and poor in stress. After processing, a quartz glass finished product of ø650x250 mm is obtained. By detecting the optical uniformity, the optical performance is 6.8 ppm, the 81% area stress birefringence is 4.5 nm / cm, and there is no stripe in other areas except the central D100 range. The optical performance is obviously better than that of the same size quartz glass prepared by the existing process. Compared with Comparative Example 1, the product demand can be met without annealing treatment.

[0049] Comparative Example 1 In the comparative example, the structure of the burner on the furnace top 1 is shown in Figure 4 .

[0050] In the comparative example, most of the structures and sizes of the furnace body are the same as those in Embodiment 1, except that the position of the torch group 4 and the straight track 10 are not arranged.

[0051] In the comparative example, the plurality of conventional torches 43 of the torch group 44 are arranged on virtual circles with radii of 100 mm, 200 mm and 300 mm, respectively. A plurality of conventional torches 43 are fixed on each virtual circle, and the number of torches on different virtual circles is different. The arrangement is shown in Figure 4 . The deposition amount and temperature thermal map are shown in Figure 5 .

[0052] A large-size synthetic quartz glass ingot with a diameter of 800 mm and a thickness of 300 mm is prepared according to the above method. The quartz glass ingot obtained above is subjected to processing treatment such as rounding, milling and polishing, and the edge of the round ingot is poor in light uniformity and stress. After processing, a quartz glass finished product with a diameter of 650 mm and a thickness of 250 mm is obtained. Through detection, the optical uniformity thereof is 19.6 ppm, there are multiple annular refractive index mutation regions, the stress birefringence of 81% area is 15 nm / cm, there are obvious grooves on the surface before milling, and there are obvious visible refractive stripes in the glass after milling. It must be subjected to an annealing program in an annealing furnace to become a qualified product.

[0053] Example 2 The difference between this example and Example 1 is that one auxiliary burner 42 is arranged on each straight track 10 in this example. The other structures of the deposition furnace are the same as those in Example 1. The auxiliary burner 42 only provides heat compensation and does not participate in the deposition of silicon dioxide.

[0054] During the deposition process, the main burner 41 and the auxiliary burner 42 are fixed in the initial arrangement position and do not move. The deposition heat map is as shown in Figure 7 .

[0055] According to the above method, a large-size synthetic quartz glass ingot with a diameter of 800 mm and a thickness of 300 mm is prepared by depositing for 48 hours. After the quartz glass ingot obtained above is subjected to processing treatment such as rounding, milling and polishing, a quartz glass finished product with a diameter of 740 mm and a thickness of 250 mm is obtained. Through detection, the optical uniformity thereof is 3.2 ppm, the stress birefringence of 81% area is 2.61 nm / cm, and there are no stripes in other regions except the central D100 range. Compared with Example 1, after the auxiliary burner 42 is added, the light uniformity and stress parameters of the edge of the ingot are obviously improved, and the usable product area is increased.

[0056] Example 3 With reference to Figure 8 , the difference between this example and Example 2 is that the crucible deposition surface 8 at the bottom of the crucible is changed from 800 mm to 2000 mm, that is, the furnace for producing an ingot with a diameter of 800 mm is directly used to produce an ingot with a diameter of 2000 mm after the crucible 7 is replaced, and therefore the radius of the virtual circle is different. The main burner 41 is arranged according to the foregoing f(x) = C(r / R) r .

[0057] A large-size synthetic quartz glass ingot with a diameter of 2000 mm and a thickness of 300 mm is prepared by depositing for 168 hours according to the above method. After processing such as rounding, milling, polishing and the like, the quartz glass ingot obtained above is processed to obtain a finished product of ø1750*250 mm. The optical uniformity is 3.2 ppm, the 81% area stress birefringence is 3.4 nm / cm, and there are no stripes except for the center D100. Compared with Example 2, the optical performance is slightly worse, but the product caliber can be changed without the need to re-manufacture the furnace, greatly meeting the flexibility of industrial production, saving fixed costs, and the product quality is still significantly better than the same size quartz glass prepared by the existing process.

[0058] The application further provides a quartz glass deposition furnace roof burner assembly.

[0059] In the preferred embodiment, a quartz glass deposition furnace roof burner assembly comprises a linear track 10 fixed to the body of the furnace roof 1 and a main torch 41, wherein, The bottom end surface of the body of the furnace roof 1 is fixed with two or more linear tracks 10 in a direction outward from the center thereof, and each linear track 10 is installed with a main torch 41 slidable thereon. The main torch 41 is used for injecting silicon-containing substances and heating. A circle is drawn with the center of the body of the furnace roof 1 as the center and the distance from the center of the body of the furnace roof 1 to the center of the main torch 41 as the radius, forming one or two or more virtual circles. When the number of virtual circles formed is greater than or equal to 2, the two or more virtual circles are arranged at non-uniform intervals to avoid ripple defects.

[0060] Specifically, the main torch 41 and the linear track 10 adopt a sliding rail mode, but are not limited to the sliding rail mode. The main torch 41 can freely move along the radial direction on the linear track 10, and can also be fixed at a point for stable operation. The number of torches between different linear tracks 10 can be equal or unequal, but at least one main torch 41 exists.

[0061] When the number of virtual circles formed is greater than or equal to 2, the radius of the virtual circle is calculated by a function f(x). The radius X1=f(1) of the main torch 41 on the first virtual circle on the innermost side, and the radius X M =f(M) of the main torch 41 on the outermost side, f(x) is a function related to the number of linear tracks 10 and the quartz glass product crystal ingot finished product to be manufactured, and f(x) is a function with a first derivative greater than 0 and a second derivative less than 0, the domain x is any positive integer between 1 and M, M is the number of virtual circles, and N is the number of linear tracks 10.

[0062] Specifically, when the number of the formed virtual circles is greater than or equal to 2, the distance between adjacent virtual circles gradually decreases along the straight track 10 from outside to inside. That is, f(M+1)-f(M) < f(M)-f(M-1).

[0063] With this gradually decreasing arrangement, that is, the gradually dense arrangement of the main torches 41, this design avoids the local accumulation of large thickness caused by arranging multiple torches on the same virtual circle, and avoids the obvious zoning (ringing) of the torch arrangement, which causes the transition area between different rings distributed in the entire finished quartz glass ingot to have a visible circular ring that affects the quality, and is beneficial to produce quartz glass ingots with higher optical uniformity.

[0064] In this embodiment, when the finished quartz glass product ingot diameter to be produced is less than 1000 mm, the radius of the virtual circle is determined by the following formula: f(x) ; (1) wherein, R is the radius of the outermost virtual circle, r and C are coefficients.

[0065] According to formula (1), the diameter relationship of the multiple virtual circles on the inside relative to the outermost virtual circle can be obtained. Formula (1) is suitable for the scene of linearly regulating the deposition rate at different radial positions.

[0066] Taking N=6 and M=2 as an example, one main torch 41 is slidably installed on each straight track 10, that is, there are 6 main torches 41, and the arrangement of the 6 main torches 41 forms two virtual circles. The diameter of the virtual circle on the inside can be obtained by substituting x=1 into the above formula (1). The coefficient r=6 can be set, which is substituted into to obtain the relationship between f(1) and R, and f(2)=R, that is, the radius of the virtual circle on the outside is R.

[0067] When the finished quartz glass product ingot diameter to be produced is equal to 1000 mm, the radius of the virtual circle is determined by the following formula: f(x)= , (2) wherein, R is the radius of the outermost virtual circle, and r and C are coefficients.

[0068] The outer peripheral torch arrangement of this formula (2) is more dense than the torch arrangement calculated by formula (1) in the outer ring, which can compensate for the edge temperature decay under large size.

[0069] Further, the plurality of straight tracks 10 are uniformly arranged in the circumferential direction of the furnace top 1 body. That is, the furnace top is uniformly arranged with N straight tracks 10 along the circumferential direction, and the straight tracks 10 at least include a first straight track 10, a second straight track 10 and a third straight track 10 arranged in sequence, and up to an Nth straight track 10. At this time, the plurality of straight tracks 10 have a fixed interval angle θ in the circumferential direction array, and the interval angle is related to the number of straight tracks 10, and the interval angle θ = 360 / N.

[0070] Further, the straight track 10 is also slidably connected with an auxiliary burner 42 for heating. The main burner 41 sprays silicon-containing substances and heats. The auxiliary burner 42 does not spray silicon-containing substances, and is only used as a burner for providing heat.

[0071] Because of the presence of the movable auxiliary burner 42, during the cooling stage after deposition is completed, stress unevenness caused by fast peripheral cooling and slow internal cooling can be avoided. After the main burner 41 stops spraying material, it can be concentrated at the center of the furnace top; the auxiliary burner 42 continues to burn, while slowly moving back and forth along the radial direction, and gradually reducing the moving range, to ensure the uniformity of the overall cooling, which can effectively reduce the internal stress of the glass, and reduce the cracks, stripes and bubbles on the edges of the finished quartz glass ingot.

[0072] The auxiliary burner 42 can be arranged at the periphery of the crucible 7 of different sizes at the same radius, to freely control the size of the high-temperature area, for ensuring the stability of the temperature environment of the deposition core area inside the furnace when the size of the crucible 7 changes; or it can be arranged inside the crucible 7 at different radii, to make up for the local low temperature caused by the circumferential uneven arrangement of the main burner 41. The auxiliary burner 42 is located inside the main burner 41.

[0073] The application also proposes a control method of a quartz glass deposition furnace.

[0074] Specifically, in the embodiment, a control method of a quartz glass deposition furnace includes the following steps: Step S10, according to the diameter of the quartz glass product ingot to be produced, determine how many virtual circles are to be arranged in the furnace top burner assembly, and determine the positions of the main burner 41 and the auxiliary burner 42; Step S20, during the preheating stage and the material spraying deposition stage of the deposition process, control the main burner 41 and the auxiliary burner 42 to be fixed; Step S30, during the material stopping and preheating stage of the deposition process, control the main burner 41 to be fixed, and control the auxiliary burner 42 to move on the straight track.

[0075] During deposition, both the main torch 41 and the auxiliary torch 42 are stationary. After the deposition is completed, the main torch 41 is retracted, and the auxiliary torch 42 is continuously moved. After the deposition is stopped, the main torch 41 is controlled to move to the end of the linear track 10 closest to the center of the body of the furnace top 1, and the auxiliary torch 42 is controlled to reciprocate outside the main torch 41 to perform annealing treatment on the crystal ingot. That is, after the deposition is completed, the quartz glass deposition furnace can be used as an annealing furnace by using the auxiliary torch 42, and the finished product does not need to be transferred back and forth, thereby improving the production efficiency.

[0076] Specifically, during annealing, all the main torches 41 are gathered to the center of the hearth (the end of the linear track 10 close to the center) to stop fuel supply, and the peripheral auxiliary torches 42 can move on the linear track 10 at a speed of 200 mm / min during the shutdown process, and the minimum radius of movement gradually increases at a speed of 50 mm / h, approaches the center of the hearth, and reduces the coverage of the heating area; the hydrogen supply amount of the auxiliary torch 42 gradually decreases at a speed of 5 L / h, and the flame outer flame combustion temperature gradually decreases from 1800°C to 1300°C, until the burner cannot maintain normal combustion of the flame, and the hearth is naturally cooled after the flame is extinguished. The movement process of the burner is as shown in Figures 7 to 8 , Figure 9 is a partial movement trajectory, the horizontal coordinate is time, and the vertical coordinate is the distance of the auxiliary lamp from the center.

[0077] After the gradient movement cooling method is used, the temperature difference between the edge and the center of the crystal ingot during cooling is ≤50°C, the edge stress is <10 nm / cm, (the traditional process is >100°C, and the edge stress is >20 nm / cm), the average stress birefringence value is reduced to below 3 nm / cm, and annealing is not required.

[0078] The following specific examples are used for illustration.

[0079] Comparative Example 1 The quartz glass deposition furnace of the embodiment includes a furnace body composed of a furnace top 1, a furnace wall 2, and a furnace bottom 3. A torch group 4 is arranged on the furnace top 1, and is used to generate heat and water by burning hydrogen-oxygen mixture, and to react with raw materials to generate SiO2 particles. Exhaust pipes 5 are symmetrically arranged on the side of the furnace wall 2, and are in communication with the inside of the furnace body. The exhaust pipes 5 are arranged 250-450 mm below the deposition surface. A rotary lifting device 6 is connected to the furnace bottom 3, and can rotate the crucible 77 around the central axis at a variable speed. The crucible deposition surface 8 has a diameter of 800 mm, is arranged on the upper end of the rotary lifting device 6, and is used to collect fused quartz particles. One main torch 41 and one auxiliary torch 42 are arranged on each moving linear track 10, the auxiliary torch 42 only provides heat compensation and does not participate in SiO2 deposition, and the main torch 41 is arranged according to f(x)=r=R=400mm. Arrangement, r=6, R=400mm.

[0080] During the deposition process, the main torch 41 and the auxiliary torch 42 are fixed in the initial arrangement position and do not move.

[0081] A large-size synthetic quartz glass ingot with a diameter of 800 mm and a thickness of 300 mm is prepared by depositing for 48 hours according to the above method. After processing such as rounding, milling, polishing, etc. of the quartz glass ingot obtained above, a finished product of quartz glass with ø740*250 mm is obtained. The optical uniformity thereof is 3.2 ppm, the 81% area stress birefringence is 2.61 nm / cm, and there are no stripes in other regions except the central D100 range.

[0082] Example 1 The structure of the quartz glass deposition furnace in this example is the same as that in Comparative Example 1. The difference from the above-mentioned Comparative Example 1 is that the main torch 41 is fixed during the deposition process, while the auxiliary torch 42 is not fixed.

[0083] During the deposition process, the auxiliary torch 42 is arranged outside the main torch 41 and is on the same linear track 10. During the product size expansion and the air burning stage after the deposition process, the auxiliary torch 42 moves on the linear track 10 to uniformly heat the ingot, compensate for the influence of uneven distribution of the burners on the furnace top 1, and control the distribution area of the high-temperature atmosphere in the furnace. The arrangement radius of the outermost torch is R, the arrangement radius of the auxiliary torch 42 is R+150 mm at the beginning of the deposition to assist in rapidly increasing the overall furnace temperature while avoiding mutual interference with the flame of the material torch; the gas quantity of the auxiliary torch 42 is reduced at the end of the deposition (the main torch stops spraying the deposition material, and the fuel continues to be sprayed), and the arrangement radius of the auxiliary torch 42 is R+75 mm. At this time, the edge of the ingot (crucible 7) is heated in a targeted manner, which is helpful to further improve the edge stress and optical uniformity parameters.

[0084] After the deposition process using the auxiliary torch 42 moving scheme, a large-size synthetic quartz glass ingot with a diameter of 800 mm and a thickness of 300 mm is produced. Compared with Comparative Example 1, the furnace warming-up time is shortened from 12 hours to 8 hours from the start of the furnace to the start of the material spraying; the optical uniformity of the finished ingot is reduced from 3.2 ppm to 2.61 ppm, and the edge stress birefringence (full bore maximum value) is reduced from 4.2 nm / cm to 2.61 nm / cm.

[0085] The above is only a preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation using the content of the specification and drawings, or direct or indirect application in other related technical fields is also included in the patent protection scope of the present application.

Claims

1. A quartz glass deposition furnace roof burner assembly characterized by, The quartz glass deposition furnace top burner assembly comprises straight tracks fixed on the top body and main torches, wherein, The bottom end surface of the top body is fixed with two or more straight tracks in a direction outward from the center of the top body, and each straight track is installed with a main torch slidable relative to the straight track, the main torch being used for injecting silicon-containing substances and heating, and a circle is drawn with the center of the top body as the center and the distance from the center of the top body to the center of the main torch as the radius, forming one or two or more virtual circles, and when the number of the formed virtual circles is greater than or equal to two, the two or more virtual circles are arranged at non-uniform intervals to avoid ripple defects.

2. The quartz glass deposition furnace roof burner assembly of claim 1, wherein, The straight tracks are also connected with auxiliary torches for heating.

3. The quartz glass deposition furnace roof burner assembly of claim 2, wherein, When the number of the formed virtual circles is greater than or equal to two, the distance between adjacent virtual circles gradually decreases in the direction from the outside to the inside along the straight tracks.

4. The quartz glass deposition furnace roof burner assembly of claim 1, wherein, When the number of the virtual circles formed is greater than or equal to 2, the radius of the virtual circle is calculated by a function f(x), the radius of the main burner on the first virtual circle in the innermost side is X1=f(1), and the radius of the main burner on the outermost side is X M =f(M), f(x) is a function related to the number of the virtual circles required to make the quartz glass product ingot finished product, and f(x) is a function with a first derivative greater than 0 and a second derivative less than 0, the domain x is any positive integer between 1 and M, M is the number of the virtual circles, and N is the number of the linear tracks.

5. The quartz glass deposition furnace roof burner assembly of claim 4, wherein, When the diameter of the quartz glass product ingot to be produced is less than 1000 mm, the radius of the virtual circle is determined according to the following formula: ； wherein R is the radius of the outermost virtual circle, is a coefficient.

6. The quartz glass deposition furnace roof burner assembly of claim 4, wherein, When the diameter of the quartz glass product ingot to be produced is greater than or equal to 1000 mm, the radius of the virtual circle is determined according to the following formula: ， wherein r is the radius of the outermost virtual circle, r, C are coefficients.

7. The quartz glass deposition furnace roof burner assembly of claim 2 wherein, The plurality of straight tracks are arranged uniformly in the circumferential direction of the top body, and the auxiliary torches are outside the main torches, and when the diameter of the quartz glass product ingot to be produced is D (mm), the number of the virtual circles is greater than D / 100.

8. A quartz glass deposition furnace characterized by comprising: The quartz glass deposition furnace top burner assembly comprises a furnace body, a crucible, an exhaust pipe, an air inlet pipe and a rotating lifting device, the furnace body comprises a furnace top, a furnace wall and a furnace bottom, and the furnace top is provided with the quartz glass deposition furnace top burner assembly according to any one of claims 2 to 7.

9. A control method of the quartz glass deposition furnace according to claim 8, characterized by, The method comprises the following steps: According to the diameter of the quartz glass product ingot to be produced, the number of the virtual circles to be arranged in the top burner assembly is determined, and the positions of the main torches and the auxiliary torches are determined; During the preheating and deposition stages, the main torches and the auxiliary torches are fixed; During the stoppage and preheating stage, the main torches are fixed, and the auxiliary torches are moved along the straight tracks.

10. The control method of the quartz glass deposition furnace according to claim 9, wherein After the deposition is stopped, the main torches are moved to the end surface of the straight tracks closest to the center of the top body, and the auxiliary torches are moved reciprocally outside the main torches to anneal the ingot.

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