Preparation method of high-temperature-resistant quartz capillary and high-temperature-resistant quartz capillary

Abstract

The invention provides a preparation method of a high-temperature-resistant quartz capillary tube and the high-temperature-resistant quartz capillary tube. The preparation method of the high-temperature-resistant quartz capillary tube comprises the following steps: providing a hollow quartz tube; the quartz tube is pulled to a heating furnace in the gravity direction, first protective gas is input into the quartz tube, and the area, close to one end of the ground, of the quartz tube is molten to form a capillary tube body; drawing the capillary tube body for annealing treatment; detecting the pipe diameter of the capillary pipe body, and adjusting the flow of the first protective gas and the traction speed of the capillary pipe body based on the pipe diameter of the capillary pipe body until the pipe diameter of the capillary pipe body is qualified; and coating the periphery of the capillary tube body with a high-temperature-resistant layer, and curing to obtain the high-temperature-resistant quartz capillary tube.

Description

Technical Field

[0001] This application relates to the field of capillary technology, and in particular to a method for preparing a high-temperature resistant quartz capillary and the high-temperature resistant quartz capillary itself. Background Technology

[0002] To improve the high-temperature resistance of quartz capillaries, most quartz capillaries are coated with a heat-resistant coating after curing. The coating is then cured. However, the bonding force between the heat-resistant coating and the quartz capillaries is weak and the porosity is high, which can easily lead to coating peeling, pores or cracks. This results in poor heat resistance and tensile strength of the quartz capillaries, affecting their reliability. Summary of the Invention

[0003] This application provides a method for preparing a high-temperature resistant quartz capillary and the high-temperature resistant quartz capillary itself, in order to solve the problem in the known technology that the weak bonding force between the quartz capillary and the high porosity affects the reliability of the quartz capillary.

[0004] This application provides a method for preparing a high-temperature resistant quartz capillary, comprising the following steps: providing a hollow quartz tube; drawing the quartz tube to a heating furnace along the direction of gravity and introducing a first protective gas into the quartz tube, wherein the portion of the quartz tube near the ground melts and forms a capillary body; drawing the capillary body for annealing treatment; detecting the diameter of the capillary body, and adjusting the flow rate of the first protective gas and the drawing speed of the capillary body based on the diameter of the capillary body until the diameter of the capillary body is qualified; coating the outer periphery of the capillary body with a high-temperature resistant layer and curing it to obtain a high-temperature resistant quartz capillary.

[0005] In one possible implementation, the outer diameter of the quartz tube is M, where 30mm ≤ M ≤ 50mm, and the inner diameter of the quartz tube is N, where 5mm ≤ N ≤ 40mm, and N < M.

[0006] In one possible implementation, the median outer diameter of the capillary body is m, 100µm≤m≤500µm, and the median inner diameter of the capillary body is n, 0<n<m and n / m≤N / M.

[0007] In one possible implementation, the traction speed of the quartz tube is V1, 0 mm / min < V1 < 1 mm / min, and the traction speed of the capillary body when it is drawn to the annealing treatment is V2, V2 = (M 2 / m 2 )×V1.

[0008] In one possible implementation, the diameter of the capillary body is detected, and the flow rate of the first protective gas and the traction speed of the capillary body are adjusted based on the diameter of the capillary body, including the following steps: The median value m1 of the outer diameter of the capillary body was detected; If the median value m1 of the outer diameter of the capillary body is greater than m, then the traction speed V2 of the capillary body is increased. If the median value m1 of the outer diameter of the capillary body is less than m, then the traction speed V2 of the capillary body is reduced.

[0009] In one possible implementation, detecting the diameter of the capillary body and adjusting the flow rate of the first protective gas and the traction speed of the capillary body based on the diameter of the capillary body further includes the following steps: The median value n1 of the inner diameter of the capillary body is detected; If the median value n1 of the inner diameter of the capillary body is greater than n, then reduce the flow rate of the first protective gas. If the median value n1 of the inner diameter of the capillary body is less than n, then the flow rate of the first protective gas is increased.

[0010] In one possible implementation, the high-temperature resistant layer is a polyimide coating, which is obtained by polymerization of a polyimide precursor solution, wherein the polyimide precursor solution includes diamine and dianhydride compounds, organic solvents, nanoparticles, and dispersants. The mass ratios of diamines and dianhydrides, organic solvents, nanopowders, and dispersants range from 11 to 21%, 74 to 86%, 0.2 to 1.4%, and 0.1 to 0.6%, respectively.

[0011] In one possible implementation, the diamine compound includes one or more of 4,4'-diaminodiphenyl ether, 4,4'-diaminobinaphthyl, isophorone diamine, and fentanyl benzoyl amine. The dianhydride compounds include one or more of pyromellitic dianhydride, biphenyl dianhydride, and hexafluorodianhydride; The organic solvent includes one or more of sulfolane, N,N-diethylacetamide, and N-methylpyrrolidone; The nanopowder contains one or more of silicon dioxide, titanium dioxide, and aluminum dioxide; The dispersant includes one or more of high molecular weight block copolymers, unsaturated polycarboxylate polymers, and modified polyurethane polymers.

[0012] In one possible implementation, coating the outer periphery of the capillary body with a high-temperature resistant layer includes the following steps: The qualified capillary bodies are then coated. The capillary body that has undergone coating is then cured.

[0013] This application also provides a high-temperature resistant quartz capillary tube, which is prepared using the above-described method for preparing high-temperature resistant quartz capillary tubes.

[0014] The method for preparing the high-temperature resistant quartz capillary of this application involves heating a quartz tube to melt its end to form a capillary body, and then coating the outer periphery of the qualified capillary body with a high-temperature resistant layer online. This allows the capillary body to be fully immersed in the high-temperature resistant coating in the coating mold, thereby ensuring full contact between the capillary body and the high-temperature resistant coating. This improves the bonding force between the capillary body and the formed high-temperature resistant layer, avoids risks such as bubbles, and increases the service life of the capillary. Attached Figure Description

[0015] Figure 1 This is a schematic flowchart of the method for preparing the high-temperature resistant quartz capillary of this application in one embodiment.

[0016] Figure 2 This is a schematic diagram of the production line structure used in one embodiment of the method for preparing the high-temperature resistant quartz capillary tube of this application.

[0017] Figure 3 This is a schematic diagram of the structure of the high-temperature resistant quartz capillary tube of this application in one embodiment.

[0018] Figure 4 This is a schematic diagram of the structure of the quartz tube corresponding to the high-temperature resistant quartz capillary tube of this application in one embodiment.

[0019] Explanation of main component symbols: 100, Preparation method of high temperature resistant quartz capillary; 200, High temperature resistant quartz capillary; 1, Gas filling tube; 2, Pressure detector; 3, Rod feeder; 4, Quartz tube; 5, Heating furnace; 6, Annealing tube; 7, First wire diameter gauge; 8, Auxiliary traction device; 9, Automatic cutting device; 10, Coating device; 11, Curing device; 12, Second wire diameter gauge; 13, Positioning wheel; 14, Main traction device; 15, Take-up machine.

[0020] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0021] The following description will refer to the accompanying drawings to provide a more complete picture of the present application. The drawings illustrate exemplary embodiments of the present application. However, the present application may be implemented in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. These exemplary embodiments are provided to make the present application thorough and complete, and to fully convey the scope of the present application to those skilled in the art. The same reference numerals denote the same or similar components.

[0022] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to limit the application. As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” are intended to also include the plural forms. Furthermore, when used herein, “comprising” and / or “including” and / or “having,” integers, steps, operations, components, and / or components, but does not exclude the presence or addition of one or more other features, regions, integers, steps, operations, components, and / or groups thereof.

[0023] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Furthermore, unless expressly defined herein, terms such as those defined in a general dictionary should be interpreted as having the same meaning as they have in the relevant art and in the content of this application, and will not be interpreted as having an idealized or overly formal meaning.

[0024] The specific embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0025] like Figures 1 to 4 As shown, this embodiment provides a high-temperature resistant quartz capillary 200, which is prepared using the high-temperature resistant quartz capillary preparation method 100.

[0026] like Figures 1 to 4 As shown, this embodiment also provides a method 100 for preparing a high-temperature resistant quartz capillary, comprising the following steps: S1, a quartz tube 4 with an internally hollow structure; S2. The quartz tube 4 is pulled to the heating furnace 5 along the direction of gravity, and the first protective gas is introduced into the quartz tube 4. The area of ​​the quartz tube 4 near the ground melts and forms a capillary body. S3. The capillary body is annealed; the diameter of the capillary body is checked, and the flow rate of the first protective gas and the traction speed of the capillary body are adjusted based on the diameter of the capillary body until the diameter of the capillary body is qualified. S4. A high-temperature resistant layer is coated on the outer periphery of the capillary body and cured to obtain a high-temperature resistant quartz capillary 200.

[0027] Thus, the method 100 for preparing the high-temperature resistant quartz capillary of this application involves heating the quartz tube 4 to melt its end to form a capillary body, and then coating the outer periphery of the qualified capillary body with a high-temperature resistant layer online, allowing the capillary body to be fully immersed in the high-temperature resistant coating in the coating mold, thereby ensuring full contact between the capillary body and the high-temperature resistant coating, thereby improving the bonding force between the capillary body and the formed high-temperature resistant layer, avoiding risks such as bubbles, and improving the service life of the capillary.

[0028] In step S1, the quartz tube 4 is a hollow cylindrical structure with open ends. The quartz tube 4 is made of high-purity quartz glass, meaning the silicon dioxide purity in the quartz tube 4 is ≥99.99%, and the content of metal ions such as trivalent aluminum ions, trivalent iron ions, sodium ions, potassium ions, and divalent calcium ions in the quartz tube 4 is <10ppm, and the hydroxyl (OH-) content is <10ppm.

[0029] The outer diameter of quartz tube 4 is M, where 30mm ≤ M ≤ 50mm, and the inner diameter of quartz tube 4 is N, where 5mm ≤ N ≤ 40mm, and N < M.

[0030] In this embodiment, the outer diameter M of the quartz tube 4 can be 30mm, 31mm, 32mm, 33mm, 34mm, 35mm, 36mm, 37mm, 38mm, 39mm, 40mm, 41mm, 42mm, 43mm, 44mm, 45mm, 46mm, 47mm, 48mm, 49mm, 50mm, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the protection scope of this application.

[0031] In this embodiment, the inner diameter N of the quartz tube 4 can be 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, 27mm, 28mm, 29mm, 30mm, 31mm, 32mm, 33mm, 34mm, 35mm, 36mm, 37mm, 38mm, 39mm, 40mm, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the protection scope of this application.

[0032] In step S2, the quartz tube 4 is fixed to the rod feeder 3 so that it is fed into the heating furnace 5 for heating. The quartz tube 4 remains vertical after entering the heating furnace 5. The traction speed of the quartz tube 4 is V1, which is the same as the operating speed of the rod feeder 3. The operating speed of the rod feeder 3 is controlled to be less than 1 mm / min, i.e., 0 mm / min < V1 < 1 mm / min. The temperature inside the heating furnace 5 is 1700℃ to 1900℃, and the furnace 5 is filled with a second protective gas to create an inert gas atmosphere to protect the quartz tube 4.

[0033] In this embodiment, the traction speed V1 of the quartz tube 4 can be 0.1 mm / min, 0.2 mm / min, 0.3 mm / min, 0.4 mm / min, 0.5 mm / min, 0.6 mm / min, 0.7 mm / min, 0.8 mm / min, 0.9 mm / min, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the protection scope of this application.

[0034] In this embodiment, the furnace temperature of the heating furnace 5 can be 1700℃, 1710℃, 1720℃, 1730℃, 1740℃, 1750℃, 1760℃, 1770℃, 1780℃, 1790℃, 1800℃, 1810℃, 1820℃, 1830℃, 1840℃, 1850℃, 1860℃, 1870℃, 1880℃, 1890℃, 1900℃, etc., but is not limited to the values ​​listed above. Other values ​​not listed within this range are also within the protection scope of this application.

[0035] In this embodiment, the second protective gas is one of helium (He) and argon (Ar), or a mixture of the two. The second protective gas is continuously introduced into the heating furnace 5 to maintain an inert gas atmosphere inside the heating furnace 5. The proportion of helium in the second protective gas is 0% to 40%, and the total flow rate of the second protective gas is 15L / min to 30L / min. The oxygen concentration in the heating atmosphere inside the heating furnace 5 is less than 50ppm.

[0036] It is understood that the total flow rate of the second protective gas can be 15L / min, 16L / min, 17L / min, 18L / min, 19L / min, 20L / min, 21L / min, 22L / min, 23L / min, 24L / min, 25L / min, 26L / min, 27L / min, 28L / min, 29L / min, 30L / min, etc., but is not limited to the values ​​listed above. Other values ​​not listed within this range are also within the scope of protection of this application.

[0037] In this embodiment, the quartz tube 4 gradually melts in the heating furnace 5, and the molten area at the end of the quartz tube 4 closest to the ground extends downwards under the action of gravity, thereby achieving the shrinkage of the quartz tube 4 to obtain a capillary body with a smaller inner and outer diameter. In addition, during the process of the quartz tube 4 shrinking to form a capillary body, a constant flow rate of first protective gas is continuously injected into the interior of the quartz tube 4 through the gas filling pipe 1. The type and composition of the first protective gas are the same as those of the second protective gas, so that the injection of the first protective gas creates a micro-pressure inside the capillary body formed by the shrinkage of the quartz tube 4, thereby applying outward pressure to the inner wall of the capillary body and thus expanding the size of the inner wall of the capillary body.

[0038] In this embodiment, a pressure detector 2 is provided at the rod feeder 3 to detect the micro-pressure generated by the first protective gas in the capillary body and the quartz tube 4. It is worth noting that the capillary body and the quartz tube 4 are connected, and the gas pressures of the two are the same.

[0039] In step S3, after the bottom of the quartz tube 4 is melted and shrunk to form a small capillary body, the formed capillary body passes sequentially through the annealing tube 6, the first wire diameter gauge 7, and the auxiliary traction device 8. Along the direction of gravity, the heating furnace 5, the annealing tube 6, the first wire diameter gauge 7, and the auxiliary traction device 8 are arranged sequentially.

[0040] In this embodiment, the capillary body undergoes annealing treatment as it passes through the annealing tube 6. The annealing tube 6 can be any of an isostatic graphite tube, quartz glass tube, high-temperature resistant ceramic tube, or high-temperature resistant metal tube, and its length ranges from 30cm to 150cm. The top of the annealing tube 6 is connected to the bottom of a high-temperature heating furnace 5, and the bottom outlet of the heating furnace 5 is directly connected to ambient air at room temperature, causing the internal temperature of the heating furnace 5 to gradually decrease from top to bottom. When the capillary body pulled from the heating furnace 5 passes through the annealing tube 6, the glass molecules inside the capillary body have sufficient time to adjust and rearrange their structure, maximizing the elimination of residual thermal stress carried from the heating furnace 5 and thus ensuring the structural strength of the capillary.

[0041] In this embodiment, the auxiliary traction device 8 can be a clamp-type belt traction machine. The clamp-type belt traction machine clamps the capillary body with two ring-shaped traction belts. During the rotation of the two traction belts, the capillary body is pulled to move, thereby pulling the small-sized capillary body formed by the melting and shrinking of the bottom of the quartz tube 4 to pass steadily through the heating furnace 5, annealing tube 6, and first wire diameter gauge 7.

[0042] In this embodiment, the first wire diameter gauge 7 can be a high-resolution laser diameter gauge with an inner diameter measurement function. This instrument is used to detect the inner and outer diameters of the capillary body after it leaves the annealing tube 6. When the inner and outer diameters of the capillary body are not up to standard, the traction speed of the auxiliary traction device 8 and the flow rate of the first protective gas are dynamically adjusted to achieve continuous online processing of the capillary body of the required size. This ensures that the inner and outer diameters of the capillary body before the coating process reach the preset values, thereby ensuring that the two processing steps of melting the quartz tube 4 to form the capillary body and coating the capillary body with a high-temperature resistant layer can be carried out continuously and online. This improves the processing efficiency of the high-temperature resistant quartz capillary 200 while ensuring the processing quality of the high-temperature resistant quartz capillary 200.

[0043] In this embodiment, the median outer diameter of the capillary body is m, where 100µm ≤ m ≤ 500µm, and the median inner diameter of the capillary body is n, where 0 < n < m and n / m ≤ N / M. If m is less than 100µm, the high-temperature resistant coating cannot be completely adsorbed onto the small surface area of ​​the capillary body, easily leading to coating sagging. If m is greater than 500µm, the minimum bending radius that the capillary body can withstand is too large, making it difficult to wind and take up the line without damage via the subsequent positioning wheel 13 and take-up machine 15. If n = 0, the internal pores of the capillary body disappear; if n = m, the capillary body wall thickness is insufficient to support the structure.

[0044] The median value of the outer diameter of a capillary body is obtained by continuously measuring the outer diameter of the capillary body at fixed intervals along its length, and then sorting the data in order of size. The value at the middle position is recorded as the median value of the outer diameter of the capillary body.

[0045] The median value of the inner diameter of a capillary body is obtained by continuously measuring the inner diameter of the capillary body at fixed intervals along its length, and then sorting the data in order of size. The value at the middle position is recorded as the median value of the inner diameter of the capillary body.

[0046] It is understood that the median value m of the outer diameter of the capillary body can be 100µm, 150µm, 200µm, 250µm, 300µm, 350µm, 400µm, 450µm, 500µm, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0047] The traction speed of the capillary body during annealing is V2, where V2 = (M 2 / m 2 The traction speed of the auxiliary traction device 8 is the same as the traction speed when the capillary body is pulled to the annealing process, that is, the traction speed of the auxiliary traction device 8 is V2. By adjusting the relationship between the running speed of the bar feeder 3 and the traction speed of the auxiliary traction device 8, it is ensured that the outer diameter and inner diameter of the formed capillary body can be within the preset range.

[0048] In this embodiment, the diameter of the capillary body is detected, and the flow rate of the first protective gas and the traction speed of the capillary body are adjusted based on the capillary body diameter, including the following steps: S31. Detect the median value m1 of the outer diameter of the capillary body; S32. If the median value m1 of the outer diameter of the capillary body is greater than m, then increase the traction speed V2 of the capillary body; if the median value m1 of the outer diameter of the capillary body is less than m, then decrease the traction speed V2 of the capillary body.

[0049] In this embodiment, detecting the diameter of the capillary body and adjusting the flow rate of the first protective gas and the traction speed of the capillary body based on the capillary body diameter also includes the following steps: S33, Detect the median value n1 of the inner diameter of the capillary body; S34. If the median value n1 of the inner diameter of the capillary body is greater than n, then reduce the flow rate of the first protective gas; if the median value n1 of the inner diameter of the capillary body is less than n, then increase the flow rate of the first protective gas.

[0050] Thus, when the median outer diameter m1 of the capillary body is detected to be equal to m, and the median inner diameter n1 of the capillary body is equal to n, that is, m1 satisfies 100µm≤m1≤500µm, 0<n1<m1 and n1 / m1≤N / M, it is ensured that the size of the capillary body before the high-temperature resistant layer coating can meet the preset range, which facilitates the subsequent coating of the high-temperature resistant layer, and ensures that the surface of the high-temperature resistant coating is free of drips and burrs and can be smoothly and without damage for winding and take-up.

[0051] Furthermore, along the traction direction of the capillary body, an automatic cutting device 9 is provided on the side of the auxiliary traction device 8 away from the first wire diameter gauge 7. During the adjustment of the inner and outer diameters of the capillary body, the automatic cutting device 9 can cut off and discard unqualified capillary bodies at a predetermined frequency. When the inner and outer diameters of the capillary body are within the preset range, the automatic cutting device 9 is turned off, and the traction speed of the current auxiliary traction device 8 and the flow rate of the first protective gas are fixed, thereby conveying the qualified capillary body to the coating station for coating operations.

[0052] For step S4, the high-temperature resistant layer is a polyimide coating, which is obtained by polymerization reaction of a polyimide precursor solution. The polyimide precursor solution includes diamine and dianhydride compounds, organic solvents, nanoparticles, and dispersants.

[0053] The mass proportions of diamines and dianhydrides, organic solvents, nanoparticles, and dispersants in the polyimide precursor solution range from 11–21%, 74–86%, 0.2–1.4%, and 0.1–0.6%, respectively.

[0054] Diamine compounds include one or more of 4,4'-diaminodiphenyl ether, 4,4'-diaminobinaphthyl, isophorone diamine, and fentanyl amine.

[0055] Dihydric compounds include one or more of pyromellitic dianhydride, biphenyl dianhydride, and hexafluorodianhydride.

[0056] Organic solvents include one or more of sulfolane, N,N-diethylacetamide, and N-methylpyrrolidone.

[0057] The nanopowder contains one or more of silicon dioxide, titanium dioxide, and aluminum dioxide.

[0058] The dispersant can be one or more of the following: high molecular weight block copolymers, unsaturated polycarboxylate polymers, and modified polyurethane polymers.

[0059] In this embodiment, the mass ratio of diamine and dianhydride compounds in the polyimide precursor solution can be 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, etc., but is not limited to the values ​​listed above. Other values ​​not listed within this range are also within the scope of protection of this application.

[0060] In this embodiment, the mass ratio of the organic solvent to the polyimide precursor solution can be 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, etc., but is not limited to the values ​​listed above. Other values ​​not listed within this range are also within the scope of protection of this application.

[0061] In this embodiment, the mass ratio of nanopowder to the polyimide precursor solution can be 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0062] In this embodiment, the mass ratio of the dispersant in the polyimide precursor solution can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, etc., but is not limited to the values ​​listed above. Other values ​​not listed within this range are also within the scope of protection of this application.

[0063] In this embodiment, coating the outer periphery of the capillary body with a high-temperature resistant layer includes the following steps: Coating is performed on qualified capillary bodies; The capillary body that has been coated is then cured.

[0064] Specifically, the qualified capillary body is drawn sequentially through the coating device 10, the curing device 11, and the second wire diameter gauge 12. After being steered by the positioning wheel 13, it is transported to the main traction device 14, whose traction speed is the same as that of the auxiliary traction device 8. When the capillary body along the entire conveying path is in a taut state (the auxiliary traction device 8 and the main traction device 14 are synchronized, and there is no redundancy in the capillary body along the entire conveying path), the curing device 11 is activated first, followed by the coating device 10, so that the high-temperature resistant coating fully coats the outer circumference of the capillary body and cures to form a dense high-temperature resistant layer.

[0065] The coating device 10 uses water bath heating or electric heating to maintain a constant temperature of the coating flowing inside (temperature range 25℃ to 40℃). The opening size of the coating mold core is k, k≥m+100µm, to ensure that the capillary body can pass through it smoothly without rubbing.

[0066] It is understood that the coating temperature maintained within the coating apparatus 10 may be 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0067] The curing device 11 is an electric heating furnace 5 that matches the curing method of the polyimide coating. The operating temperature of the electric heating furnace 5 is 250°C to 400°C, and the electric heating furnace 5 is set to one section. It can be understood that, depending on the required final coating thickness and coating curing rate, the electric heating furnace 5 can also be increased to two to four sections.

[0068] It is understood that the operating temperature of the electric heating furnace 5 can be 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, etc., but is not limited to the values ​​listed above. Other values ​​not listed within this range are also within the scope of protection of this application.

[0069] After the coating device 10 and curing device 11 are fully turned on, observe the reading of the second wire diameter gauge 12. After confirming that the high-temperature resistant layer has been cured and the dimensions are stable, turn off the auxiliary traction device 8 and open the belt clamp (to prevent the bare capillary body from being damaged by rubbing against the belt). Wind the high-temperature resistant quartz capillary 200 at the outlet of the main traction device 14 onto the take-up machine 15. The finished high-temperature resistant quartz capillary 200 is collected by winding it through the take-up machine 15.

[0070] The median thickness of the high-temperature resistant layer is p, where 10µm ≤ p ≤ 50µm. If the thickness of the high-temperature resistant layer is less than 10µm, the coating's temperature resistance is easily damaged by scratches. If the thickness of the high-temperature resistant layer is greater than 50µm, it is difficult to achieve uniform curing of the coating, and bubbles are easily generated on the outer layer, affecting both appearance and temperature resistance.

[0071] It is understood that the median value p of the thickness of the high-temperature resistant layer can be 10µm, 11µm, 12µm, 13µm, 14µm, 15µm, 16µm, 17µm, 18µm, 19µm, 20µm, 21µm, 22µm, 23µm, 24µm, 25µm, 26µm, 27µm, 28µm, 29µm, 30µm, 31µm, 32µm, 33µm, 34µm, 35µm, 36µm, 37µm, 38µm, 39µm, 40µm, 41µm, 42µm, 43µm, 44µm, 45µm, 46µm, 47µm, 48µm, 49µm, 50µm, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0072] Example 1 A quartz tube 4 with an inner diameter of 20 mm and an outer diameter of 40 mm is provided and fixed on a rod feeder 3 and fed into a heating furnace 5. The operating speed of the rod feeder 3 is 0.5 mm / min. The furnace temperature of the heating furnace 5 is 1800℃. A second protective gas, formed by mixing 30% helium and 70% argon, is continuously fed into the heating furnace 5 at a flow rate of 20 L / min.

[0073] After the bottom of the quartz tube 4 is melted and shrunk to form a capillary body, it is slowly cooled through the annealing tube 6 to eliminate residual thermal stress. Based on the inner and outer diameters of the quartz tube 4 detected by the first wire diameter gauge 7, the flow rate of the first protective gas and the traction speed of the auxiliary traction device 8 are dynamically adjusted until the inner and outer diameters of the capillary body are within the qualified range.

[0074] Subsequently, the qualified capillary body passes through the coating device 10 in sequence. The coating device 10 applies polyimide coating to the outer surface of the capillary body by means of compressed air to achieve complete wetting and coating. The temperature of the polyimide coating maintained in the coating device 10 is 34°C, and the coated capillary body is pulled into the curing device 11. The working temperature of the curing device 11 is 350°C.

[0075] The polyimide coating is obtained by polymerization of a polyimide precursor solution, which includes 8% 4,4'-diaminodiphenyl ether, 10% pyromellitic dianhydride, 81% N,N-diethylacetamide, 0.6% silica, and 0.4% unsaturated polycarboxylic acid polymer dispersant.

[0076] Testing revealed that the median inner diameter of the high-temperature resistant quartz capillary 200 is 180µm, the median outer diameter is 340µm, and the median thickness of the high-temperature resistant layer is 20µm. The high-temperature resistant layer is smooth and free of bubbles or obvious damage, with a coating non-roundness ≤6%. All high-temperature resistant quartz capillary 200 tubes passed the 100kpsi tension screening, with an average tensile breaking force ≥60N.

[0077] Comparative Example 1 The only difference between it and Example 1 is that it was not annealed.

[0078] Testing revealed that the median inner diameter of the high-temperature resistant quartz capillary 200 was 180µm, the median outer diameter was 300µm, and the median thickness of the high-temperature resistant layer was 20µm. The high-temperature resistant layer was smooth and free of bubbles or obvious damage, with a coating non-roundness ≤6%. Not all high-temperature resistant quartz capillary 200s passed the 100kpsi tension screening, with an average tensile breaking force ≤30N. Compared to Example 1, the high-temperature resistant quartz capillary 200 produced in Comparative Example 1, lacking an annealing process, resulted in the accumulation of residual thermal stress within the capillary body, making it more susceptible to breakage under external forces.

[0079] Comparative Example 2 The only difference between this and Example 1 is that a pre-formed capillary body is provided, with a median outer diameter of 300µm and a median inner diameter of 180µm, and the capillary body is coated and cured in accordance with the method described in Example 1.

[0080] After testing, the median thickness of the high-temperature resistant layer of the high-temperature resistant quartz capillary 200 was found to be 20µm. The high-temperature resistant layer was smooth and free of bubbles or obvious damage, with a coating non-roundness ≤6%. Not all of the high-temperature resistant quartz capillary 200 passed the 100kpsi tension screening, with an average tensile breaking force ≤30N. Compared to Example 1, the strength of the high-temperature resistant quartz capillary 200 produced in Comparative Example 2 was significantly reduced. This is because the pre-formed capillary body needs to be guided into the coating device 10 using a guide wheel system or similar device; the friction and impact during this process can damage the capillary surface, causing scratches or micro-cracks.

[0081] Comparative Example 3 The only difference between it and Example 1 is that the high-temperature resistant layer is applied using a spraying process.

[0082] Testing revealed that the median inner diameter of the high-temperature resistant quartz capillary 200 was 180µm, the median outer diameter was 300µm, and the median thickness of the high-temperature resistant layer was 20µm. The surface of the high-temperature resistant layer had a granular, uneven texture and contained bubbles, with a coating non-roundness >6%. Not all high-temperature resistant quartz capillary 200s passed the 100kpsi tension screening, with an average tensile breaking force ≤40N. Compared to Example 1, the high-temperature resistant quartz capillary 200 produced in Comparative Example 3 exhibited insufficient coating adhesion and was affected by bubbles, impacting both its temperature resistance and tensile strength.

[0083] The specific embodiments of this application have been described above with reference to the accompanying drawings. However, those skilled in the art will understand that various changes and substitutions can be made to the specific embodiments of this application without departing from the scope of this application. All such changes and substitutions fall within the scope defined by this application.

Claims

1. A method for preparing a high-temperature resistant quartz capillary, characterized in that, Includes the following steps: Provides quartz tubes with an internally hollow structure; The quartz tube is pulled to the heating furnace along the direction of gravity, and a first protective gas is introduced into the quartz tube. The area of ​​the quartz tube near the ground melts and forms a capillary body. The capillary body is then subjected to annealing treatment. The diameter of the capillary body is detected, and based on the diameter of the capillary body, the flow rate of the first protective gas and the traction speed of the capillary body are adjusted until the diameter of the capillary body is qualified. A high-temperature resistant layer is coated on the outer periphery of the capillary body and cured to obtain a high-temperature resistant quartz capillary.

2. The method for preparing the high-temperature resistant quartz capillary as described in claim 1, characterized in that, The outer diameter of the quartz tube is M, where 30mm ≤ M ≤ 50mm, and the inner diameter of the quartz tube is N, where 5mm ≤ N ≤ 40mm, and N < M.

3. The method for preparing the high-temperature resistant quartz capillary as described in claim 2, characterized in that, The median outer diameter of the capillary body is m, where 100µm ≤ m ≤ 500µm, and the median inner diameter of the capillary body is n, where 0 < n < m and n / m ≤ N / M.

4. The method for preparing the high-temperature resistant quartz capillary as described in claim 3, characterized in that, The traction speed of the quartz tube is V1, 0 mm / min < V1 < 1 mm / min, and the traction speed of the capillary body when it is drawn to the annealing treatment is V2, V2 = (M 2 / m 2 )×V1.

5. The method for preparing the high-temperature resistant quartz capillary as described in claim 4, characterized in that, The process of detecting the diameter of the capillary body and adjusting the flow rate of the first protective gas and the traction speed of the capillary body based on the diameter includes the following steps: The median value m1 of the outer diameter of the capillary body was detected; If the median value m1 of the outer diameter of the capillary body is greater than m, then the traction speed V2 of the capillary body is increased. If the median value m1 of the outer diameter of the capillary body is less than m, then the traction speed V2 of the capillary body is reduced.

6. The method for preparing the high-temperature resistant quartz capillary as described in claim 4, characterized in that, The process of detecting the diameter of the capillary body, adjusting the flow rate of the first protective gas and the traction speed of the capillary body based on the diameter of the capillary body, further includes the following steps: The median value n1 of the inner diameter of the capillary body is detected; If the median value n1 of the inner diameter of the capillary body is greater than n, then reduce the flow rate of the first protective gas. If the median value n1 of the inner diameter of the capillary body is less than n, then the flow rate of the first protective gas is increased.

7. The method for preparing the high-temperature resistant quartz capillary as described in claim 1, characterized in that, The high-temperature resistant layer is a polyimide coating, which is obtained by polymerization of a polyimide precursor solution. The polyimide precursor solution includes diamine and dianhydride compounds, organic solvents, nanoparticles, and dispersants. The mass ratios of diamines and dianhydrides, organic solvents, nanopowders, and dispersants range from 11 to 21%, 74 to 86%, 0.2 to 1.4%, and 0.1 to 0.6%, respectively.

8. The method for preparing the high-temperature resistant quartz capillary as described in claim 7, characterized in that, The diamine compounds include one or more of 4,4'-diaminodiphenyl ether, 4,4'-diaminobinaphthyl, isophorone diamine, and quinacrine. The dianhydride compounds include one or more of pyromellitic dianhydride, biphenyl dianhydride, and hexafluorodianhydride; The organic solvent includes one or more of sulfolane, N,N-diethylacetamide, and N-methylpyrrolidone; The nanopowder contains one or more of silicon dioxide, titanium dioxide, and aluminum dioxide; The dispersant includes one or more of high molecular weight block copolymers, unsaturated polycarboxylate polymers, and modified polyurethane polymers.

9. The method for preparing the high-temperature resistant quartz capillary as described in claim 1, characterized in that, The process of coating the outer periphery of the capillary body with a high-temperature resistant layer includes the following steps: The qualified capillary bodies are then coated. The capillary body that has undergone coating is then cured.

10. A high-temperature resistant quartz capillary tube, characterized in that, It is prepared using the method for preparing high-temperature resistant quartz capillary tubes as described in any one of claims 1 to 9.

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