Ultralow-expansion titanium-doped synthetic quartz glass and preparation method thereof

Abstract

The invention discloses ultralow-expansion titanium-doped synthetic quartz glass, which is prepared by depositing and sintering TiO2 particles and SiO2 particles generated by hydrolysis reaction. The invention also discloses a preparation method of the ultralow-expansion titanium-doped synthetic quartz glass. The preparation method comprises the following steps: respectively gasifying a silicon source compound raw material and a titanium source compound raw material, inputting the gasified raw materials into a furnace body, and carrying out flame hydrolysis on the gasified raw materials and hydrogen and oxygen input into the furnace body to generate TiO2 particles and SiO2 particles; or inputting the silicon source compound raw material and the titanium source compound raw material which are evaporated at high temperature into the furnace body, and carrying out high-temperature hydrolysis reaction on the silicon source compound raw material and the titanium source compound raw material and hydrogen and oxygen which are input into the furnace body to generate TiO2 particles and SiO2 particles; tiO2 particles and SiO2 particles generated by the hydrolysis reaction are deposited on a rotating substrate to form a SiO2-TiO2 loose body, and the SiO2-TiO2 loose body is sintered to prepare the titanium-doped quartz glass. The expansion coefficient is low, and the quality of the quartz glass formed by sintering is high; an oxidizing atmosphere is adopted during sintering, so that conversion from Ti < 3 + > to Ti < 4 + > is promoted; the process is simplified, and oxygen gasification atmosphere sintering is achieved through negative pressure sintering and negative pressure.

Description

Technical Field

[0001] The invention relates to a special method for producing quartz or fused silica products, in particular to an ultra-low expansion titanium-doped synthetic quartz glass and a preparation method thereof. Background Art

[0002] By 1968, Corning successfully developed low-expansion quartz glass containing TiO2 and named it ultra low expansion (ULE) quartz glass. ULE quartz glass has a smaller thermal expansion coefficient, and even within a certain temperature range, the thermal expansion coefficient is close to zero. With its excellent performance, SiO2-TiO2 glass can be used as atomic clock cavities, materials for large telescope embryos, delay line glass for radars and color televisions, spacecraft windows, extreme ultraviolet lithography machine masks, reflectors, etc., providing a material basis and technical guarantee for the development of semiconductors, national defense, aerospace and other fields. Patent with publication number CN106430913A: Preparation method of quartz glass with low expansion coefficient and quartz glass, during sintering, an oxidizing atmosphere gas flow is introduced into the sintering space to place the sintering space in an oxidizing environment, so that the titanium-doped silica loose body is sintered in an oxidizing environment. During sintering, the oxidizing environment can prevent Ti 4+ To Ti 3+ Transformation and promotion of Ti 3+ To Ti 4+ Transformation, so that the final titanium-doped quartz glass contains more Ti 4+ Titanium ions, less Ti 3+ Titanium ions can reduce its expansion coefficient; it also uses negative pressure environment for sintering, and the pores in the silica loose body are easy to discharge. There is no need to sinter the silica loose body step by step as in the prior art. The silica loose body can be sintered directly at one time to form a quartz glass with higher quality than the method of sintering the silica loose body step by step in the prior art, which improves the sintering efficiency of the silica loose body and reduces the cost. Patent with publication number CN116375315A: A method for preparing titanium-doped synthetic quartz sand, using direct synthesis chemical vapor deposition to prepare mixed powder particles of silica and titanium dioxide, which uses high-purity chemicals containing silicon and titanium as raw materials to ensure the purity of the powder raw materials; the silicon-titanium powder particles are further sprayed and granulated to obtain powder particles with uniform distribution of silicon and titanium on a micron scale, which ensures the uniformity of titanium element distribution in subsequent quartz glass products. Although the prior art has made certain technical improvements in the preparation of high-quality titanium-doped quartz glass, it has increased the complexity and energy consumption of the preparation process. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects in the prior art and provide an ultra-low expansion titanium-doped synthetic quartz glass with a low expansion coefficient. The quartz glass formed by sintering is of high quality. The sintering is carried out in an oxidizing atmosphere to promote the Ti 3+ To Ti 4+ Transformation; using negative pressure to absorb oxygen into the sintering space in the furnace body, saving energy consumption, and even eliminating the air pump required for gas input, saving the number of equipment; it also simplifies the process, through negative pressure sintering and using negative pressure, to achieve oxygenated atmosphere sintering.

[0004] To achieve the above object, the technical solution of the present invention is to design an ultra-low expansion titanium-doped synthetic quartz glass, wherein the quartz glass is formed by sintering TiO2 particles and SiO2 particles generated by a hydrolysis reaction and then deposited.

[0005] The technical scheme of the present invention is a method for preparing ultra-low expansion titanium-doped synthetic quartz glass, which is prepared by the following steps in sequence: a silicon source compound raw material and a titanium source compound raw material are respectively gasified and input into a furnace body, and then hydrolyzed with hydrogen and oxygen input into the furnace body to form TiO2 particles and SiO2 particles; or a silicon source compound raw material and a titanium source compound raw material evaporated at high temperature are input into the furnace body, and then hydrolyzed with hydrogen and oxygen input into the furnace body at high temperature to form TiO2 particles and SiO2 particles; TiO2 particles and SiO2 particles generated by the hydrolysis reaction are deposited on a rotating substrate to form a SiO2-TiO2 loose body, and the SiO2-TiO2 loose body is sintered to prepare titanium-doped quartz glass. Sintering is performed directly after the hydrolysis reaction. Compared with the prior art method of first generating TiO2 particles and SiO2 particles and then sintering them using a sintering device, only one device is required, and the efficiency is also improved. If flame hydrolysis is used, the efficiency is higher, but the energy consumption is slightly higher; if high-temperature hydrolysis is used, the efficiency is slightly lower, but the energy consumption is low.

[0006] A further technical solution is that the silicon source compound raw material and the titanium source compound raw material are fed into the furnace body driven by a carrier gas; Or silicon source compound raw materials, titanium source compound raw materials, and carrier gas are introduced into the furnace body under negative pressure suction; Or the silicon source compound raw material and the titanium source compound raw material are input into the furnace body under the driving of the carrier gas and negative pressure suction. The input of the gasified or high-temperature evaporated silicon source compound raw material and the titanium source compound raw material can be realized simply by the driving of the carrier gas, or by negative pressure suction, or by both negative pressure suction and the input of the carrier gas to drive the input of the silicon source compound raw material and the titanium source compound raw material. The input of oxygen and hydrogen can also adopt these three methods.

[0007] A further technical solution is that the silicon source compound raw material and the titanium source compound raw material are SiCl4 and TiCl4 respectively; and the carrier gas is high-purity nitrogen gas that has been dehydrated.

[0008] A further technical solution is to evacuate the furnace body and then input gasified or high-temperature evaporated silicon source compound raw materials, titanium source compound raw materials and carrier gas, hydrogen and oxygen, and then perform flame hydrolysis or high-temperature hydrolysis to deposit SiO2-TiO2 loose bodies; during the hydrolysis reaction, oxygen is also input into the sintering space of the furnace body and the SiO2-TiO2 loose bodies are sintered to obtain quartz glass; While inputting silicon source compound raw materials, titanium source compound raw materials, carrier gas, hydrogen and oxygen, the furnace body is continuously evacuated. This method first evacuates the furnace body and sintering is performed in a negative pressure environment, which helps to form higher quality titanium-doped quartz glass. The gases are sucked in and then burned by negative pressure. {The input of carrier gas can also be combined to realize the input of gasified or high-temperature evaporated silicon source compound raw materials and titanium source compound raw materials; the input of air pump can be combined to realize the input of hydrogen and oxygen to achieve the required amount}. During the hydrolysis reaction, additional oxygen is also input into the sintering space to ensure that (the loose body generated by the hydrolysis reaction) is sintered in an oxidizing atmosphere to promote Ti 3+ To Ti 4+ Transformation; using negative pressure to absorb gas into the furnace body, saving energy consumption, and even eliminating the air pump required for gas input, saving the number of equipment; it also simplifies the process, through negative pressure sintering and using negative pressure, to achieve oxygenated atmosphere sintering.

[0009] A further technical solution is that the furnace body is connected with an oxygen pipeline, a hydrogen pipeline and a feed pipe, and a rotating base plate is arranged at the bottom of the furnace body; the oxygen pipeline is also connected with a branch pipe, and one end of the branch pipe away from the oxygen pipeline is connected to the furnace body at the sintering space; a gas valve is arranged on the branch pipe; A combustion nozzle is fixedly arranged at the bottom of the furnace body, facing the bottom end face of the deposited SiO2-TiO2 loose body, so as to sinter the SiO2-TiO2 loose body into quartz glass. A combustion nozzle required for flame hydrolysis can be arranged at the upper part of the furnace body (if it is high temperature hydrolysis, it is not necessary to arrange it).

[0010] The advantages and beneficial effects of the present invention are as follows: the furnace body is first evacuated, and sintering is performed in a negative pressure environment, which is helpful to form a titanium-doped quartz glass with higher quality. After the gases are sucked in by the negative pressure, a high-temperature hydrolysis reaction (or a flame hydrolysis reaction is generated by combustion) occurs. During the hydrolysis reaction, additional oxygen is input into the sintering space to ensure that (the loose body generated by the hydrolysis reaction) is sintered in an oxidizing atmosphere, which promotes the Ti 3+ To Ti 4+Transformation; using negative pressure to absorb gas into the furnace body, saving energy consumption, and even eliminating the air pump required for gas input, saving the number of equipment; it also simplifies the process, through negative pressure sintering and using negative pressure, to achieve oxygenated atmosphere sintering.

[0011] The expansion coefficient is low, and the quartz glass formed by this sintering is of high quality; Sintering is performed directly after the hydrolysis reaction. Compared with the existing technology of first generating TiO2 particles and SiO2 particles and then using a sintering device for sintering, only one device is needed, and the efficiency is also improved. If flame hydrolysis is used, the efficiency is higher, but the energy consumption is slightly higher; if high-temperature hydrolysis is used, the efficiency is slightly lower, but the energy consumption is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of a furnace body in Example 1 of ultra-low expansion titanium-doped synthetic quartz glass of the present invention; Figure 2 yes Figure 1 The main view; Figure 3 yes Figure 2 Schematic diagram of oxygen pipeline and branch pipe; Figure 4 is a schematic diagram of a furnace body in Embodiment 2 or Embodiment 3 of the present invention; Figure 5 is a schematic diagram of a furnace body in a fourth embodiment of the present invention; Figure 6 yes Figure 5 an enlarged schematic diagram of the lower end portion of; Figure 7 yes Figure 6 A partial enlarged schematic diagram of the middle impeller and its surrounding parts.

[0013] In the figure: 1. furnace body; 2. oxygen pipeline; 3. hydrogen pipeline; 4. feed pipe; 5. rotating substrate; 6. branch pipe; 7. sintering space; 8. gas valve; 9. air pump; 10. flow meter; 11. controller; 12. negative pressure pump; 13. combustion nozzle; 14. rotating shaft; 15. flexible shaft; 16. impeller; 17. axle; 18. connecting rod; 19. pressure relief valve. DETAILED DESCRIPTION

[0014] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0015] Embodiment 1: Figures 1 to 3 As shown (for ease of illustration, Figure 1 Only the feed pipe is shown, and the oxygen pipe and hydrogen pipe are not shown; Figure 3The lower end of the middle branch pipe is not shown). The present invention is an ultra-low expansion titanium-doped synthetic quartz glass, which is formed by sintering TiO2 particles and SiO2 particles generated by hydrolysis reaction.

[0016] A method for preparing ultra-low expansion titanium-doped synthetic quartz glass, which is prepared by the following steps in sequence: high-temperature evaporated silicon source compound raw materials and titanium source compound raw materials are input into a furnace body and subjected to high-temperature hydrolysis reaction with hydrogen and oxygen input into the furnace body to generate TiO2 particles and SiO2 particles; the TiO2 particles and SiO2 particles generated by the hydrolysis reaction are deposited on a rotating substrate to form a SiO2-TiO2 loose body, and the SiO2-TiO2 loose body is sintered to prepare titanium-doped quartz glass; the silicon source compound raw materials and the titanium source compound raw materials are input into the furnace body driven by a carrier gas; Or silicon source compound raw materials, titanium source compound raw materials, and carrier gas are introduced into the furnace body under negative pressure suction; Or the silicon source compound raw material and the titanium source compound raw material are input into the furnace body under the drive of the carrier gas and the negative pressure suction; the silicon source compound raw material and the titanium source compound raw material are SiCl4 and TiCl4 respectively; the carrier gas is high-purity nitrogen gas without moisture; the furnace body is evacuated by a negative pressure pump 12, and then the silicon source compound raw material, the titanium source compound raw material and the carrier gas, hydrogen and oxygen that are evaporated at high temperature are input, and then high-temperature hydrolysis is carried out to be deposited into SiO2-TiO2 loose body; during the hydrolysis reaction (by opening the gas valve on the branch pipeline), oxygen is also input into the sintering space of the furnace body and the SiO2-TiO2 loose body is sintered to obtain quartz glass; While the silicon source compound raw material, the titanium source compound raw material, the carrier gas, the hydrogen gas and the oxygen are input, the furnace body is continuously evacuated (the burner is kept in a negative pressure state). The furnace body 1 is connected with an oxygen pipeline 2, a hydrogen pipeline 3 and a feed pipe 4, and a rotating base plate 5 is arranged at the bottom of the furnace body 1; the oxygen pipeline 2 is also connected with a branch pipe 6, and the end of the branch pipe 6 away from the oxygen pipeline is connected to the furnace body at the sintering space 7; a gas valve 8 is arranged on the branch pipe; gas valves 8 are arranged on the oxygen pipeline, hydrogen pipeline and feed pipe (the ends of the oxygen pipeline, hydrogen pipeline and feed pipe away from the furnace body can also be connected with an air pump 9; the gas valves on the oxygen pipeline, hydrogen pipeline and feed pipe are throttle valves, and the oxygen pipeline, hydrogen pipeline and feed pipe are also provided with a flow meter 10, and the air pump, throttle valve, flow meter and controller 11 arranged outside the burner are connected by signal); by detecting the gas flow in each pipe, if the required material ratio cannot be reached, the opening of the corresponding throttle valve is increased, and the air pump is turned on if the throttle valve is opened to the maximum and still cannot reach the ratio; so the energy consumption is low, and the air pump is activated only when the usage requirement cannot be met. Two feeding pipes are provided to achieve mixing of silicon source raw materials and titanium source raw materials during feeding, thereby ensuring uniformity of titanium doping in quartz glass. A combustion nozzle 13 is also fixedly provided at the bottom of the furnace body 1, facing the bottom end face of the deposited SiO2-TiO2 loose body, so as to achieve sintering of the SiO2-TiO2 loose body into quartz glass.

[0017] Embodiment 2: The difference from Embodiment 1 is that Figure 4 As shown, the furnace body is evacuated, and then the gas valve on the oxygen pipeline is opened to input oxygen, and then the gasified (or high-temperature evaporated) silicon source compound raw material, titanium source compound raw material, carrier gas, hydrogen and oxygen are simultaneously input; the burner is kept evacuated during the whole process; The burner comprises a furnace body 1, which is connected with an oxygen pipeline 2, a hydrogen pipeline 3 and a feed pipe 4, and a rotating base plate 5 is arranged at the bottom of the furnace body; Gas valves 8 are provided on the oxygen pipeline, hydrogen pipeline and feed pipe; The method of simultaneously inputting the silicon source compound raw material, the titanium source compound raw material, the carrier gas, the hydrogen and the oxygen is to open the gas valve on the feed pipe to realize negative pressure inhalation and to open the gas valve on the hydrogen pipeline to realize negative pressure inhalation; the gas valve on the oxygen pipeline is opened first, and it is kept open at this time to continue the negative pressure inhalation; by evacuating the furnace body to realize sintering in a negative pressure environment, higher quality quartz glass can be formed, the sintering efficiency is improved, and the cost is reduced; and the negative pressure is utilized to absorb oxygen into the sintering space in the furnace body, which is helpful to promote Ti 3+ To Ti 4+ Transformation, so that the final titanium-doped quartz glass contains more Ti 4+ Titanium ions, less Ti 3+Titanium ions can reduce its expansion coefficient; by first opening the air valve on the oxygen pipeline, oxygen is sucked into the sintering space due to the negative pressure, and then the air valves on other pipelines are opened to input the mixed gas and simultaneously burn to produce a flame hydrolysis reaction (or high-temperature hydrolysis reaction); the negative pressure pump is kept evacuated throughout the whole process to maintain the negative pressure condition, and the gasified (or high-temperature evaporated) silicon source, titanium source and hydrogen and oxygen are also continuously input to complete the combustion (or high-temperature hydrolysis), so the energy consumption is low. Compared with the original technology, each gas source air pump needs to continuously deliver air, but now by using negative pressure, each air pump can even be eliminated.

[0018] Embodiment 3: The difference from Embodiment 2 is that Figure 4 As shown, the furnace body is evacuated (slightly negative pressure, such as 1000 Pa), and then the gas valve on the feed pipe 4 is opened (to achieve the use of slight negative pressure) to simultaneously input the gasified (or high-temperature evaporated) silicon source compound raw materials, titanium source compound raw materials and carrier gas, and the gas valves on the oxygen pipeline 2 and the hydrogen pipeline 3 are opened to simultaneously input hydrogen and oxygen, and at the same time, the vacuum is continued (the same vacuum degree is maintained, and the gas can continue to be inhaled) and high-temperature hydrolysis is performed to generate TiO2 particles and SiO2 particles (combustion, combustion flame hydrolysis to generate TiO2 particles and SiO2 particles) and then the gas valve 8 on the feed pipe 4 and the hydrogen pipeline 3 is closed and the furnace body is continued to be evacuated to a lower vacuum degree (500 Pa), and then sintering is performed under a negative pressure environment; (this method can reduce the waste of oxygen, and it is only inhaled into the sintering space under negative pressure during sintering) (since the explosion limit of hydrogen is 4.0% to 75.6% by volume concentration, oxygen is continued to be inhaled under the subsequent negative pressure state to make the sintering space have more oxygen, so there is no need to worry about the safety problem of the explosion limit of hydrogen) Embodiment 4: The difference from Embodiment 1 is that Figures 5 to 7 As shown, the furnace body 1 is fed with (high temperature evaporated or gasified) silicon source compound raw materials, titanium source compound raw materials, carrier gas, compressed hydrogen and compressed oxygen, and then a hydrolysis reaction is carried out; the carrier gas is compressed nitrogen; during the hydrolysis reaction, compressed oxygen is fed into the sintering space so that sintering is carried out in an oxidizing atmosphere; The furnace body is connected with an oxygen pipeline 2, a hydrogen pipeline 3 and a feed pipe 4, and a rotating base plate 5 is arranged at the bottom of the furnace body; the oxygen pipeline 2 is also connected with a branch pipe 6, and the end of the branch pipe 6 away from the oxygen pipeline is connected to the furnace body at the sintering space 7; a gas valve 8 is arranged on the branch pipe; the feed pipe, hydrogen pipeline and oxygen pipeline are also provided with gas valves 8; The furnace body comprises a shell and a shell cover hinged to the shell; One section of the feed pipe or oxygen pipeline or hydrogen pipeline is located at the part of the rotating base plate 5 whose rotating axis is located outside the shell, and the exposed end of the rotating axis 14 is fixedly connected with a flexible shaft 15, and the flexible shaft 15 passes through the feed pipe or oxygen pipeline or hydrogen pipeline (because the flexible shaft passes through the feed pipe or oxygen pipeline or hydrogen pipeline, a rotary seal is used at the passing point to ensure the airtightness of the feed pipe or oxygen pipeline or hydrogen pipeline), and then is fixedly connected with the wheel shaft 17 of the impeller 16 arranged in the feed pipe or oxygen pipeline or hydrogen pipeline, and the impeller 16 is rotatably arranged on the connecting rod 18, and the connecting rod is fixedly connected to the inner wall of the feed pipe or oxygen pipeline or hydrogen pipeline; The scheme of the first embodiment can also be used as a reference. The gas valves on the oxygen pipeline, the hydrogen pipeline and the feed pipe are throttle valves. The oxygen pipeline, the hydrogen pipeline and the feed pipe are also provided with flow meters. The throttle valves and the flow meters are connected to the controller signal arranged outside the furnace body. By detecting the gas flow in each pipe, if the required material ratio cannot be reached, the opening of the corresponding throttle valve is increased (in this case, there is no situation where the throttle valve cannot be opened to the maximum, because it is compressed gas, so this scheme does not require an air pump); {The input of compressed gas is used to drive the rotation of the rotating substrate using its pressure airflow, which can save the driving source of the rotating substrate and further reduce energy consumption. In addition, since it is compressed nitrogen, compressed hydrogen and compressed oxygen, there is no need for an air pump, and the air intake can be achieved by directly opening the air valves on the feed pipe, hydrogen pipeline and oxygen pipeline. The (high-temperature evaporated or gasified) silicon source compound raw material and titanium source compound raw material can also be mixed into the carrier gas in advance. In this way, when the air valve on the feed pipe is opened, the compressed nitrogen automatically moves into the furnace body, and at the same time drives the silicon source compound raw material and titanium source compound raw material to move into the furnace body. Then, the air valve on the branch pipe is opened to input compressed oxygen into the sintering space; Since the pipelines of the furnace body are fixedly arranged on the inner top wall of the shell cover, the sealing of the furnace body is ensured by the flange seal between the shell cover and the shell after the shell cover is closed; The feed pipe and / or oxygen pipeline (the oxygen pipeline can also be replaced by a hydrogen pipeline) passes through the rotating base plate whose rotating shaft is located outside the burner shell, and blows the impeller on the flexible shaft fixedly connected to the rotating shaft to drive the rotating base plate to rotate; Therefore, the use of compressed gas input in combination with the soft shaft impeller and other settings can not only save the driving source of the rotating substrate, but also save the air pump due to the use of compressed gas input. A pressure relief valve 19 is arranged on the furnace body at a relative position to the branch pipe to avoid safety hazards caused by excessive gas pressure in the furnace body. In addition, since the branch pipe is used to input oxygen into the sintering space to form an oxidizing atmosphere for sintering, the pressure relief valve is arranged at a relative position to the branch pipe (specifically, the relative position of the connection between the branch pipe and the furnace body). When the gas pressure in the furnace body is too high, when the pressure relief valve is opened, an airflow from the sintering space to the pressure relief valve is formed in the sintering space, which is beneficial to the discharge of pores in the silica loose body and the formation of higher quality quartz glass. This method eliminates the process of vacuuming with a negative pressure pump and does not require a negative pressure pump.

[0019] The input of compressed oxygen into the sintering space combined with the setting of the pressure relief valve position can facilitate the outward discharge of pores in the silicon dioxide loose body, thereby forming higher quality quartz glass, eliminating the process of vacuuming with a negative pressure pump and eliminating the need for a negative pressure pump.

[0020] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An ultra-low expansion titanium-doped synthetic quartz glass, characterized in that: The quartz glass is formed by sintering TiO2 particles and SiO2 particles generated by hydrolysis reaction after deposition.

2. The method for preparing the ultra-low expansion titanium-doped synthetic quartz glass according to claim 1, characterized in that: The method is prepared by the following steps: a silicon source compound raw material and a titanium source compound raw material are respectively gasified and then fed into a furnace body and hydrolyzed with hydrogen and oxygen flame fed into the furnace body to form TiO2 particles and SiO2 particles; or a silicon source compound raw material and a titanium source compound raw material evaporated at high temperature are fed into a furnace body and hydrolyzed with hydrogen and oxygen fed into the furnace body to form TiO2 particles and SiO2 particles; TiO2 particles and SiO2 particles generated by the hydrolysis reaction are deposited on a rotating substrate to form a SiO2-TiO2 loose body, and the SiO2-TiO2 loose body is sintered to prepare titanium-doped quartz glass.

3. The method for preparing ultra-low expansion titanium-doped synthetic quartz glass according to claim 2, characterized in that: The silicon source compound raw material and the titanium source compound raw material are fed into the furnace body driven by the carrier gas; Or silicon source compound raw materials, titanium source compound raw materials, and carrier gas are introduced into the furnace body under negative pressure suction; Or the silicon source compound raw material and the titanium source compound raw material are input into the furnace body under the driving of the carrier gas and the negative pressure suction.

4. The method for preparing ultra-low expansion titanium-doped synthetic quartz glass according to claim 3, characterized in that: The silicon source compound raw material and the titanium source compound raw material are SiCl4 and TiCl4 respectively; the carrier gas is high-purity nitrogen gas without moisture.

5. The method for preparing ultra-low expansion titanium-doped synthetic quartz glass according to claim 4, characterized in that: The furnace body is evacuated and then gasified or high-temperature evaporated silicon source compound raw materials, titanium source compound raw materials and carrier gas, hydrogen and oxygen are input, and then flame hydrolysis or high-temperature hydrolysis is performed to deposit SiO2-TiO2 loose bodies; during the hydrolysis reaction, oxygen is also input into the sintering space of the furnace body and the SiO2-TiO2 loose bodies are sintered to obtain quartz glass; The furnace body is continuously evacuated while the silicon source compound raw material, the titanium source compound raw material, the carrier gas, the hydrogen gas and the oxygen gas are input.

6. The method for preparing ultra-low expansion titanium-doped synthetic quartz glass according to claim 5, characterized in that: The furnace body is connected with an oxygen pipeline, a hydrogen pipeline and a feed pipe, and a rotating base plate is arranged at the bottom of the furnace body; the oxygen pipeline is also connected with a branch pipe, and one end of the branch pipe away from the oxygen pipeline is connected to the furnace body at the sintering space; a gas valve is arranged on the branch pipe; A combustion nozzle is fixedly arranged at the bottom of the furnace body, facing the bottom end surface of the deposited SiO2-TiO2 loose body, so as to sinter the SiO2-TiO2 loose body into quartz glass.

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