Annealing load fixture and annealing method for quartz glass with very low residual stress

Abstract

The application provides an annealing loading tool and an annealing method of quartz glass with extremely low residual stress, which can be used in the technical field of quartz glass annealing. The annealing loading tool comprises a container body and a cover, and the container body and the cover are double-layer vacuum structures; an opening is arranged at the upper end of the container body, and a bearing table for bearing a quartz glass mass is arranged in the inner cavity of the container body; and the cover is used for closing the opening. By using the heat preservation performance of the double-layer vacuum structure of the annealing loading tool, the cooling rate of the quartz glass mass in the annealing cooling process is reduced, the internal and external temperature difference of the quartz glass mass in the annealing process is reduced, the stress of the quartz glass mass is better eliminated, the residual stress in the quartz glass mass is reduced to an extremely low level, and the annealing effect of the quartz glass mass is greatly improved.

Description

Technical Field

[0001] This application relates to the field of quartz glass annealing technology, and more particularly to an annealing loading fixture and annealing method for quartz glass with extremely low residual stress. Background Technology

[0002] Quartz glass is an indispensable material in many fields, including the semiconductor industry, high-end optics, high-energy lasers, and aerospace. Among its key performance indicators are stress birefringence, optical homogeneity, metallic impurities, and damage threshold. While different applications may prioritize different performance indicators, stress birefringence is crucial for all applications because it reflects the internal stress state of the quartz glass. Since stress affects the optical properties and mechanical strength of quartz glass, its stress birefringence is of paramount importance.

[0003] When quartz glass is exposed to high temperatures, its internal molecular structure changes, especially during rapid cooling. Due to the large temperature difference between the inside and outside, the outer layer cools quickly and contracts, while the inner layer cools slowly and continues to expand or contract relatively slowly. This uneven contraction and expansion generates stress within the quartz glass. In addition to the permanent stress caused by the uneven thermal expansion and contraction during cooling, mechanical stress can also be generated at the edges of quartz glass during processing.

[0004] In existing technologies, annealing is the most common method for eliminating stress in quartz glass. During annealing, by controlling parameters such as heating rate, holding temperature and time, and cooling rate, the molecular structure inside the quartz glass can be relaxed, thereby eliminating stress. However, current annealing methods still suffer from poor annealing effects, which hinders the elimination of stress in quartz glass. Summary of the Invention

[0005] This application provides an annealing loading fixture and annealing method for quartz glass with extremely low residual stress, in order to optimize the existing annealing methods for quartz glass and solve the technical problem that the current annealing effect is poor and affects the stress relief of quartz glass.

[0006] According to the first aspect disclosed in this application, this application provides an annealing loading fixture for quartz glass with extremely low residual stress, including a container body and a cap, wherein the container body and the cap are a double-layer vacuum structure;

[0007] The container body has an opening at the upper end, and the inner cavity of the container body is provided with a support platform for holding the quartz glass weight.

[0008] The cap is used to close the opening.

[0009] In one feasible implementation, the support platform includes a ring platform disposed on the inner wall of the container body.

[0010] In one feasible implementation, the support platform includes a plurality of bosses, which are arranged around the inner wall of the container body.

[0011] In one possible implementation, the lower end of the cover is provided with a first protrusion, the first protrusion being adapted to the shape and size of the opening.

[0012] In one feasible implementation, a second protrusion is provided at the lower end of the container body, and the shape and size of the second protrusion are adapted to the opening.

[0013] In one feasible implementation, the vacuum level of the double-layer vacuum structure is 50 Pa.

[0014] According to the second aspect disclosed in this application, this application provides an annealing apparatus for quartz glass with extremely low residual stress, including an annealing loading fixture as described in any one of the first aspects, and an annealing furnace.

[0015] According to a third aspect disclosed in this application, this application provides an annealing method for quartz glass with extremely low residual stress, based on the annealing apparatus as described in the second aspect, comprising:

[0016] After placing the annealing loading device containing the quartz glass weight into the annealing furnace, the annealing furnace is sealed, and inert gas is continuously introduced into the annealing furnace and pressurized.

[0017] The furnace temperature of the annealing furnace is raised to 1100-1250℃ at a heating rate of 100℃ / h and held for 8-10 hours.

[0018] The furnace temperature of the annealing furnace is reduced to 700℃ at a cooling rate of 10-20℃ / h, and then the annealing furnace is allowed to cool naturally.

[0019] Once the temperature of the annealing furnace drops below 100°C, open the annealing furnace and remove the quartz glass block to allow it to cool naturally to room temperature.

[0020] In one feasible implementation, the furnace temperature of the annealing furnace is reduced to 700°C at a cooling rate of 10-20°C / h, comprising:

[0021] The furnace temperature of the annealing furnace is reduced to 1000℃ at a cooling rate of 10-15℃ / h.

[0022] The furnace temperature of the annealing furnace is reduced to 700℃ at a cooling rate of 15-20℃ / h.

[0023] In one feasible implementation, the method further includes:

[0024] When the furnace temperature of the annealing furnace drops to 500°C, the introduction of inert gas into the annealing furnace is stopped.

[0025] According to the third aspect disclosed in this application, this application provides a quartz glass product prepared based on the annealing method described in any one of the second aspects.

[0026] Compared with the prior art, this application has the following advantages:

[0027] This application provides an annealing loading fixture and annealing method for quartz glass with extremely low residual stress. By loading the quartz glass ingot to be annealed into an annealing loading fixture with a double-layer vacuum structure, not only can the internal radial and axial temperature field of the quartz glass ingot be made uniform during the cooling process, reducing the internal and external temperature difference of the quartz glass ingot during the cooling process, but also the heat preservation performance of the double-layer vacuum structure of the annealing loading fixture can provide a good heat preservation effect for the quartz glass ingot during the cooling process, reducing the cooling rate of the quartz glass ingot during the annealing cooling process, reducing the internal and external temperature difference caused by the inconsistent cooling rates between the outside and inside of the quartz glass, better eliminating the stress of the quartz glass ingot, reducing the residual stress in the quartz glass ingot to an extremely low level, and greatly improving the annealing effect of the quartz glass ingot. Attached Figure Description

[0028] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0029] Figure 1 A schematic diagram of the structure of an annealing loading fixture for quartz glass with extremely low residual stress provided in an embodiment of this application;

[0030] Figure 2 Top view of the internal cross-section of the container body Figure 1 ;

[0031] Figure 3 Top view of the internal cross-section of the container body Figure 2 ;

[0032] Figure 4 This is a schematic diagram of the stacking structure of the annealing loading fixture provided in the embodiments of this application;

[0033] Figure 5 A schematic diagram of an annealing apparatus for quartz glass with extremely low residual stress provided in an embodiment of this application;

[0034] Figure 6This is a schematic flowchart of an annealing method for quartz glass with extremely low residual stress, provided as an embodiment of this application.

[0035] Explanation of reference numerals in the attached figures:

[0036] 100-Cap;

[0037] 101 - First protrusion;

[0038] 200 - Container body;

[0039] 201-Rounding Taiwan;

[0040] 202 - Second protrusion;

[0041] 203 - convex surface;

[0042] 300-quartz glass weight;

[0043] 400-annealing furnace;

[0044] 500-Pressure Pump.

[0045] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0046] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0047] Quartz glass is an indispensable material in many fields, including the semiconductor industry, high-end optics, high-energy lasers, and aerospace. Among its key performance indicators are stress birefringence, optical homogeneity, metallic impurities, and damage threshold. While the specific performance indicators emphasized may differ across applications, stress birefringence is crucial for all applications because it reflects the internal stress state of the quartz glass. Since stress affects the optical properties and mechanical strength of quartz glass, stress birefringence is of paramount importance.

[0048] When quartz glass is exposed to high temperatures, its internal molecular structure changes, especially during rapid cooling. Due to the large temperature difference between the inside and outside, the outer layer cools quickly and contracts, while the inner layer cools slowly and continues to expand or contract relatively slowly. This uneven contraction and expansion generates stress within the quartz glass. In addition to the permanent stress caused by the uneven thermal expansion and contraction during cooling, mechanical stress can also be generated at the edges of quartz glass during processing.

[0049] In existing technologies, the most common method for eliminating stress in quartz glass is annealing. During annealing, by controlling parameters such as heating rate, holding temperature and time, and cooling rate, the molecular structure inside the quartz glass can be relaxed, thereby eliminating stress.

[0050] Currently, the annealing fixtures used for quartz glass ingots are generally flat plate bearing structures. These independent bearings support the quartz glass ingots, keeping them separated and preventing heat accumulation, thus improving the uniformity of heating and cooling. However, the high temperature environment during annealing can introduce impurities and contaminate the quartz glass, and direct contact between the quartz glass and the bearing can lead to uneven axial temperature distribution. Furthermore, during the annealing cooling stage, the outer layer of the quartz glass ingot cools rapidly while the inner layer cools slowly, resulting in a large temperature difference that can cause permanent stress within the quartz glass that is difficult to eliminate. The rapid heating and cooling rates further exacerbate this temperature difference, negatively impacting annealing and ultimately affecting the stress relief effect.

[0051] Therefore, the existing annealing methods have not yet adequately addressed the impact of the internal and external temperature difference of the quartz glass material on stress relief during the annealing process, and the problem of poor annealing effect still exists, affecting the stress relief of quartz glass.

[0052] To address the aforementioned technical problems, this application proposes an annealing loading fixture and annealing method for quartz glass with extremely low residual stress. By utilizing the thermal insulation performance of the double-layer vacuum structure of the annealing loading fixture, the cooling rate of the quartz glass ingot during the annealing cooling process is reduced, thereby decreasing the internal and external temperature difference of the quartz glass ingot during annealing. This better eliminates the stress in the quartz glass ingot, reducing the residual stress in the quartz glass ingot to an extremely low level and greatly improving the annealing effect of the quartz glass ingot.

[0053] The technical solution of the annealing loading fixture and annealing method for quartz glass with extremely low residual stress provided in this application will be described in detail below through specific embodiments. It should be noted that the following embodiments may exist alone or in combination with each other, and the same or similar content may not be described again in different embodiments.

[0054] Figure 1 A schematic diagram of an annealing loading fixture for quartz glass with extremely low residual stress is provided in this application embodiment. (See attached diagram.) Figure 1 In some embodiments, the annealing loading fixture process includes a container body 200 and a cap 100, the container body 200 and the cap 100 being a double-layer vacuum structure; the upper end of the container body 200 is provided with an opening, and the inner cavity of the container body 200 is provided with a support platform for holding the quartz glass weight 300; the cap 100 is used to close the opening.

[0055] In this embodiment, by loading the quartz glass ingot 300 to be annealed into an annealing fixture with a double-layer vacuum structure, not only can the internal radial and axial temperature field of the quartz glass ingot 300 be made uniform during the cooling process, reducing the internal and external temperature difference of the quartz glass ingot 300 during the cooling process; but also, through the heat preservation performance of the double-layer vacuum structure of the annealing fixture, the quartz glass ingot 300 can be well preserved during the cooling process, reducing the cooling rate of the quartz glass ingot 300 during the annealing cooling process, reducing the internal and external temperature difference caused by the inconsistent cooling rates between the outside and inside of the quartz glass ingot 300, better eliminating the stress of the quartz glass ingot 300, reducing the residual stress in the quartz glass ingot 300 to an extremely low level, and greatly improving the annealing effect of the quartz glass ingot 300.

[0056] In addition, loading the quartz glass ingot 300 to be annealed into the annealing loading fixture can also isolate impurities from contact with the quartz glass ingot 300, thereby preventing impurity contamination.

[0057] Specifically, the quartz glass cylinder 300 is generally a transparent, round column, but there are also irregularly shaped cylinders with special requirements, such as square or hexagonal shapes. Therefore, the container body 200 can be set as rectangular or circular according to the shape of the quartz glass cylinder 300.

[0058] Optionally, the container body 200 and the cap 100 are made of quartz glass, and the quartz glass used to make the container body 200 and the cap 100 has a purity of not less than 99.998%.

[0059] The container body 200 and the cap 100 are made of quartz glass, which can prevent the introduction of other impurities that could affect the annealing effect.

[0060] See Figure 2 Optionally, the support platform includes a ring platform 201, which is disposed on the inner wall of the container body 200.

[0061] Among them, an annular platform 201 is provided on the inner wall of the container body 200. The annular platform 201 can be used to stably support the quartz glass ingot 300, and can also reduce the contact area between the quartz glass ingot 300 and the container body 200, so as to avoid the container body 200 affecting the annealing effect of the quartz glass ingot 300.

[0062] See Figure 3 Optionally, the support platform includes multiple bosses 203, which are arranged around the inner wall of the container body 200.

[0063] Multiple protrusions 203 are provided on the inner wall of the container body 200. The protrusions 203 support the quartz glass weight 300, which can further reduce the contact area between the quartz glass weight 300 and the container body 200.

[0064] See Figure 1 Optionally, the lower end of the cover 100 is provided with a first protrusion 101, which is adapted to the shape and size of the opening.

[0065] The first protrusion 101 at the lower end of the cap 100 is adapted to the shape and size of the opening of the container body 200. Therefore, the first protrusion 101 can be inserted into the opening, thereby improving the sealing and stability of the cap 100.

[0066] See Figure 4 Optionally, a second protrusion 202 is provided at the lower end of the container body 200, and the second protrusion 202 is adapted to the shape and size of the opening.

[0067] The second protrusion 202 at the lower end of the container body 200 is adapted to the shape and size of the opening of the container body 200. Therefore, the second protrusion 202 of the container body 200 can be inserted into the opening of other container bodies 200, thereby stacking multiple annealing loading fixtures to improve the utilization rate and annealing efficiency of the container through multi-layer stacking of annealing loading fixtures.

[0068] Optionally, the vacuum level of the double-layer vacuum structure is 50 Pa.

[0069] The vacuum level of the double-layer vacuum structure affects the heat preservation effect of the annealing loading fixture. Therefore, in order to ensure sufficient heat preservation performance during annealing loading, the vacuum level of the double-layer vacuum structure is set to 50 Pa.

[0070] Figure 5 A schematic diagram of an annealing apparatus for quartz glass with extremely low residual stress is provided in this application embodiment. (See attached diagram.) Figure 5 In some embodiments, the annealing apparatus includes the annealing loading fixture described above, and an annealing furnace 400.

[0071] Specifically, the annealing loading fixture is used to support the annealed quartz glass ingot 300 so that the quartz glass ingot 300 can be heated evenly during the annealing process.

[0072] Specifically, the working principle of the annealing furnace 400 is to use a fan to circulate air and make the temperature distribution inside the furnace uniform. Then, the workpiece is placed in the annealing furnace and slowly heated to a certain temperature. After holding at that temperature for a period of time, it is cooled at an appropriate rate (usually natural cooling, sometimes controlled cooling). This allows the internal structure of the workpiece to relax and remove residual stress.

[0073] Optionally, the annealing furnace 400 is provided with a vent hole for introducing inert gas into the annealing furnace.

[0074] Optionally, the annealing furnace 400 is connected to a pressure pump 500, which is used to pressurize the annealing furnace 400.

[0075] In this embodiment, by loading the quartz glass ingot 300 to be annealed into the container body 200 of the annealing loading fixture, and then placing the annealing loading fixture in the annealing furnace for annealing, the heat preservation performance of the double-layer vacuum structure of the annealing loading fixture can be utilized to reduce the cooling rate of the quartz glass ingot 300 during the annealing cooling process, reduce the internal and external temperature difference of the quartz glass ingot 300 during the annealing process, better eliminate the stress of the quartz glass ingot 300, and reduce the residual stress in the quartz glass ingot 300 to an extremely low level, which greatly improves the annealing effect of the quartz glass ingot 300.

[0076] In addition, loading the quartz glass ingot 300 to be annealed into the annealing loading fixture can also isolate impurities from contact with the quartz glass ingot 300, thereby preventing impurity contamination.

[0077] Specifically, the annealing furnace is a tube furnace or a box furnace, and the annealing furnace can have various shapes and structures such as round, square, hexagonal, and octagonal.

[0078] Figure 6 This is a schematic flowchart of an annealing method for quartz glass with extremely low residual stress provided in an embodiment of this application. (See attached diagram.) Figure 5 In some embodiments, the annealing method is based on the annealing apparatus described above, and the process includes the following steps:

[0079] S601, after placing the annealing loading device containing the quartz glass weight into the annealing furnace, the annealing furnace is sealed, and inert gas is continuously introduced into the annealing furnace and pressurized.

[0080] Introducing inert gas into the annealing furnace can reduce the rate of temperature change of the quartz glass ingot during heating and cooling in subsequent annealing processes, improve the uniformity of the temperature field inside the furnace, thereby reducing the temperature difference between the inside and outside of the quartz glass ingot and enhancing the stress relief effect of annealing. The thermal conductivity of inert gas increases slightly under pressure, and its convection is more stable; pressurizing the annealing furnace can further optimize the uniformity of the temperature field inside the furnace.

[0081] Optionally, helium (He) can be used as the inert gas. He has a smaller molecular weight, which allows for better temperature uniformity during heating, thus reducing residual stress and achieving a better annealing effect. Simultaneously, as an inert gas, helium prevents unnecessary reactions and helps control the temperature. Specifically, the helium purity should be ≥99.9999%.

[0082] Optionally, when loading the quartz glass weight, ensure that the quartz glass weight is stably supported on the support platform inside the annealing loading fixture container and does not contact the inner wall of the container, so as to avoid uneven heating caused by the contact between the quartz glass weight and the inner wall of the annealing loading fixture container.

[0083] Optionally, the quartz glass ingot is ultrasonically cleaned with anhydrous ethanol or deionized water before being placed in the annealing furnace.

[0084] The quartz glass ingots that need to be annealed are ultrasonically cleaned with anhydrous ethanol or deionized water to remove contaminants from the surface of the quartz glass ingots and to prevent impurities from reacting at high temperatures.

[0085] S602, with a heating rate of 100℃ / h, raises the furnace temperature of the annealing furnace to 1100-1250℃ and holds it at that temperature for 8-10 hours.

[0086] The annealing furnace temperature is raised to 1100-1250℃. During the heating process, the atomic mobility inside the quartz glass ingot gradually increases, preparing for subsequent stress relief. After reaching the annealing temperature, the ingot is held at this temperature for a period of time to allow sufficient atomic rearrangement and recrystallization to occur, thus eliminating internal stress. Because crystallization of quartz glass reduces its light transmittance and mechanical strength, the annealing temperature is set at 1100-1250℃, avoiding temperatures exceeding 1300℃ to prevent crystallization. The holding time is set at 8-10 hours, and temperature fluctuations should be controlled within ±5℃ to ensure full stress release from the quartz glass ingot.

[0087] S603, with a cooling rate of 10-20℃ / h, lowers the furnace temperature of the annealing furnace to 700℃, and then allows the annealing furnace to cool naturally.

[0088] By slowly cooling down, internal stress within the material can be eliminated more effectively, grains can be refined, and the microstructure can be homogenized, thereby significantly improving the mechanical properties of the quartz glass ingot.

[0089] Optionally, the furnace temperature of the annealing furnace is reduced to 700℃ at a cooling rate of 10-20℃ / h, including:

[0090] Step 1: Reduce the furnace temperature of the annealing furnace to 1000℃ at a cooling rate of 10-15℃ / h.

[0091] In this stage, cooling is carried out at a relatively slow rate. The main purpose is to minimize the internal stress generated in the quartz glass ingot during the cooling process. The slower cooling rate helps to ensure uniform changes in the internal structure of the material and avoids the generation of new internal stress due to excessive temperature gradient.

[0092] Step 2: Reduce the furnace temperature of the annealing furnace to 700℃ at a cooling rate of 15-20℃ / h.

[0093] The quartz glass ingot has already undergone high-temperature holding and the first stage of cooling, resulting in sufficient stress relief within its internal structure. At this point, cooling at a faster rate can quickly reduce the material temperature to the predetermined range, thereby shortening the overall annealing time and improving annealing efficiency.

[0094] Optionally, when the furnace temperature of the annealing furnace drops to 500°C, the introduction of inert gas into the annealing furnace should be stopped.

[0095] When the furnace temperature of the annealing furnace drops to 500℃, most of the internal stress of the quartz glass ingot has been eliminated. At this point, stopping the inert gas supply has little impact on the quartz glass ingot. Specifically, before stopping the inert gas supply, the flow rate of the inert gas can be gradually reduced to allow the quartz glass ingot to gradually adapt to the environment without inert gas protection.

[0096] S604. Once the temperature of the annealing furnace drops below 100°C, open the annealing furnace and remove the quartz glass block to allow it to cool naturally to room temperature.

[0097] The annealing furnace should be turned on only when the furnace temperature drops below 100°C to avoid the quartz glass block cracking due to temperature difference.

[0098] In this embodiment, by loading the quartz glass ingot to be annealed into an annealing loading fixture with a double-layer vacuum structure, the heat preservation performance of the double-layer vacuum structure of the annealing loading fixture can be utilized to reduce the cooling rate of the quartz glass ingot during the annealing cooling process, thereby reducing the temperature difference between the inside and outside of the quartz glass ingot during the annealing process. Furthermore, by controlling parameters such as heating rate, holding temperature and time, and cooling rate, the molecular structure inside the quartz glass can be relaxed, thereby better eliminating the stress in the quartz glass ingot and reducing the residual stress in the quartz glass ingot to an extremely low level, which greatly improves the annealing effect of the quartz glass ingot.

[0099] Specifically, the stress of the quartz glass ingot after annealing is ≤0.2nm / cm, and the content of metallic impurities is <10ppb. It can be seen that the residual stress of the quartz glass ingot has been reduced to an extremely low level, while the content of metallic impurities remains basically unchanged. The annealing method of this application has excellent annealing effect and can prevent contamination of the quartz glass ingot.

[0100] Based on the above embodiments, the technical solution of this application will be further explained below through several sets of annealing tests.

[0101] Annealing test 1:

[0102] Two quartz glass ingots, each 200 mm in diameter and 100 mm thick, were placed inside a double-layered vacuum quartz glass container with an inner diameter of 240 mm and a depth of 150 mm. The container was then placed in a sealed annealing furnace, and 150 cubic meters of helium gas were introduced. The furnace temperature was raised from room temperature at a rate of 100 °C / h to 1150 °C, maintained at 1150 °C for 8 hours, then lowered to 1000 °C at a rate of 10-15 °C / h, and then further lowered to 700 °C at a rate of 15-20 °C / h before being cooled within the furnace.

[0103] Before annealing, the stress values ​​of the two quartz glass weights were 15 nm / cm and 12 nm / cm, respectively, and after annealing, the stress values ​​were 0.2 nm / cm and 0.1 nm / cm, respectively. The results of metal impurity detection of samples taken before annealing were 9 ppb and 7 ppb, respectively, and the results of metal impurity detection of samples taken after annealing were 9 ppb and 8 ppb, respectively.

[0104] Annealing test 2:

[0105] A quartz glass ingot with a diameter of 300 mm and a thickness of 90 mm was placed inside a double-walled vacuum quartz glass container with an inner diameter of 340 mm and a depth of 130 mm. This container was then placed in a sealed annealing furnace, and 150 cubic meters of helium gas were introduced. The furnace temperature was raised from room temperature at a rate of 100 °C / h to 1150 °C, maintained at 1150 °C for 8 hours, then lowered to 1000 °C at a rate of 10-15 °C / h, and then further lowered to 700 °C at a rate of 15-20 °C / h before being cooled within the furnace.

[0106] The stress value of the quartz glass ingot before annealing was 10.5 nm / cm, and the stress value after annealing was 0.2 nm / cm. The result of metal impurity detection of the sample before annealing was 10 ppb, and the result of metal impurity detection of the sample after annealing was 9 ppb.

[0107] Comparative experiment:

[0108] A quartz glass block of the same size as in Example 1 was placed inside an open, single-layer quartz glass container and then placed in an annealing furnace. The furnace temperature was increased from room temperature to 1150°C at a rate of 100°C / h, maintained at 1150°C for 8 hours, then decreased to 1000°C at a rate of 10-15°C / h, and then decreased to 700°C at a rate of 15-20°C / h, before being cooled in the furnace.

[0109] The stress value of the quartz glass ingot before annealing was 15 nm / cm, and the stress value after annealing was 10 nm / cm. The result of metal impurity detection of the sample before annealing was 30 ppb, and the result of metal impurity detection of the sample after annealing was 58 ppb.

[0110] As can be seen, compared with the comparative test, the annealing test using the technical solution of this application, with the cooperation of the annealing loading fixture, annealing device, and annealing method in the technical solution of this application, significantly improved the residual stress index in the quartz glass ingot after annealing, without introducing new metallic impurities. This indicates that the annealing method of this application can better eliminate the stress in the quartz glass ingot and effectively improve the annealing effect of the quartz glass ingot.

[0111] In some embodiments, this application also provides a quartz glass product prepared based on the annealing method described above.

[0112] In this embodiment, the quartz glass product prepared by the above annealing method has the advantages of low residual stress and low content of metallic impurities.

[0113] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0114] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0115] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0116] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0117] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0118] In the above embodiments, the descriptions of each embodiment have their own emphasis. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments. The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0119] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the appended claims.

[0120] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. An annealing loading fixture for reducing residual stress in quartz glass, characterized in that, Includes the container body and the cap; The container body and the lid are a double-layer vacuum structure; the vacuum degree of the double-layer vacuum structure is 50 Pa to provide heat preservation performance; The container body has an opening at the upper end, and the inner cavity of the container body is provided with a support platform for holding the quartz glass weight. The cap is used to close the opening.

2. The annealing loading fixture according to claim 1, characterized in that, The support platform includes a ring platform, which is disposed on the inner wall of the container body.

3. The annealing loading fixture according to claim 1, characterized in that, The support platform includes multiple protrusions, which are arranged around the inner wall of the container body.

4. The annealing loading fixture according to any one of claims 1-3, characterized in that, The lower end of the cover is provided with a first protrusion, which is adapted to the shape and size of the opening.

5. The annealing loading fixture according to any one of claims 1-3, characterized in that, The lower end of the container body is provided with a second protrusion, which is adapted to the shape and size of the opening.

6. An annealing apparatus for reducing residual stress in quartz glass, characterized in that, Includes the annealing loading fixture as described in any one of claims 1-5, and the annealing furnace.

7. An annealing method for quartz glass with extremely low residual stress, characterized in that, Based on the annealing apparatus as described in claim 6, comprising: After placing the annealing loading device containing the quartz glass weight into the annealing furnace, the annealing furnace is sealed, and inert gas is continuously introduced into the annealing furnace and pressurized. The furnace temperature of the annealing furnace is raised to 1100-1250℃ at a heating rate of 100℃ / h and held for 8-10 hours. The furnace temperature of the annealing furnace is reduced to 700℃ at a cooling rate of 10-20℃ / h, and then the annealing furnace is allowed to cool naturally. Once the temperature of the annealing furnace drops below 100°C, open the annealing furnace and remove the quartz glass block to allow it to cool naturally to room temperature.

8. The annealing method according to claim 7, characterized in that, The annealing furnace temperature is reduced to 700℃ at a cooling rate of 10-20℃ / h, including: The furnace temperature of the annealing furnace is reduced to 1000℃ at a cooling rate of 10-15℃ / h. The furnace temperature of the annealing furnace is reduced to 700℃ at a cooling rate of 15-20℃ / h.

9. The annealing method according to any one of claims 7-8, characterized in that, The method further includes: When the furnace temperature of the annealing furnace drops to 500°C, the introduction of inert gas into the annealing furnace is stopped.

10. A quartz glass product, characterized in that, The quartz glass product is prepared based on the annealing method described in any one of claims 7-9.

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