Quartz tube containing porous coating and preparation method thereof

Abstract

The invention provides a quartz tube containing a porous coating and a preparation method thereof. The quartz tube comprises a quartz tube body; the porous coating is located on the inner wall of the quartz tube body, and the porous coating is of a porous structure formed by stacking micro-nano particles. The porous coating provided by the invention can provide a buffer effect for thermal stress generated by thermal expansion coefficient difference between the quartz tube body and the sediment on the inner wall of the quartz tube body, and can effectively reduce the problem of quartz tube fracture caused by stress difference caused by the thermal expansion coefficient difference between the quartz tube body and the sediment; and the service life of the quartz tube is prolonged.

Description

Technical Field

[0001] At least one embodiment of the present application relates to a quartz tube, and more particularly to a quartz tube containing a porous coating and a preparation method thereof. Background Art

[0002] Tunnel Oxide Passivating Contact (TOPcon) solar cells offer advantages such as high cell efficiency, high bifaciality, low degradation, low temperature coefficient, and excellent low-light performance, and have become a mainstream product in the photovoltaic field. Compared to the Passivated Emitter and Rear Cell (PERC) cell era, their process is more complex, with the addition of oxidation and intrinsic polysilicon deposition.

[0003] Among the doped polysilicon routes, low-pressure chemical vapor deposition (LPCVD) technology is the most mature and widely used. However, during LPCVD equipment operation, the quartz tubes typically need to be replaced every two to three months. This, in addition to the cost of the tubes and other accessories, results in significant production capacity losses, severely limiting the equipment's lifespan and cell cost management. Therefore, preventing quartz tube cracking and extending its lifespan is a pressing challenge in the solar cell industry. Summary of the Invention

[0004] In view of this, in order to at least partially solve the above-mentioned technical problems, the present application provides a quartz tube containing a porous coating and a preparation method thereof, so as to extend the service life of the quartz tube.

[0005] In order to achieve the above objectives, the technical solutions of this application are as follows:

[0006] According to an embodiment of one aspect of the present application, a quartz tube is provided, comprising: a quartz tube body; and a porous coating located on the inner wall of the quartz tube body, wherein the porous coating has a porous structure formed by stacking micro-nano particles.

[0007] According to an embodiment of another aspect of the present application, a method for preparing a quartz tube is provided, comprising: mixing a particulate sol and a film-forming aid to obtain a film-forming precursor sol; and spraying the film-forming precursor sol on the inner wall of a quartz tube body and drying it, and obtaining a quartz tube body containing a porous coating after heat treatment.

[0008] According to the quartz tube with a porous coating provided in the above embodiment of the present application, a porous coating is formed on the inner wall of the quartz tube body, which effectively alleviates the thermal stress caused by the large difference in thermal expansion coefficient between the sediments deposited in the quartz tube, such as polysilicon, and the quartz tube body during use, thereby effectively reducing the occurrence of quartz tube body cracking caused by the long-term action of this thermal stress, which is conducive to improving the service life of the quartz tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present application, and are not limitations to the present application.

[0010] Figure 1 A schematic diagram of a quartz tube containing a porous coating provided in an embodiment of the present application;

[0011] Figure 2 A schematic flow chart of a method for preparing a quartz tube containing a porous coating provided in an embodiment of the present application;

[0012] Figure 3 This is an optical microscope image of a porous silica coating with a porosity of 36% provided in Example 1 of the present application;

[0013] Figure 4 This is an optical microscope image of a porous silica coating with a porosity of 70% provided in Example 2 of the present application;

[0014] Figure 5 This is an optical microscope image of a porous silica coating with a porosity of 62% provided in Example 3 of the present application;

[0015] Figure 6 This is an optical microscope image of a porous silica coating with a porosity of 51% provided in Example 4 of the present application;

[0016] Figure 7 This is an optical microscope image of a porous silica coating with a porosity of 43% provided in Example 5 of the present application;

[0017] Figure 8 This is an optical microscope image of a porous silica coating with a porosity of 73% provided in Example 6 of the present application;

[0018] Figure 9 This is an optical microscope image of a porous silica coating with a porosity of 21% provided in Example 7 of the present application;

[0019] Figure 10 An optical microscope image of a porous silica coating with a porosity of 15% provided in Comparative Example 1 of the present application;

[0020] Figure 11 An optical microscope image of a porous silica coating with a porosity of 73% provided in Comparative Example 2 of the present application; and

[0021] Figure 12 Schematic diagram of the hardness and bonding force corresponding to the porous silica coatings with different porosities provided in the examples and comparative examples of the present application.

[0022] Description of reference numerals:

[0023] 1-quartz tube body;

[0024] 2-Porous coating. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of this application more clear, this application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0026] In the detailed description that follows, for ease of explanation, numerous specific details are set forth to provide a comprehensive understanding of the embodiments of the present application. However, it is apparent that one or more embodiments may be implemented without these specific details. Furthermore, in the following description, descriptions of known structures and techniques are omitted to avoid unnecessarily obscuring the concepts of the present application.

[0027] The terms used herein are only for describing specific embodiments and are not intended to limit the present application. The term "comprising" used herein indicates the existence of features, steps, operations, but does not exclude the existence or addition of one or more other features.

[0028] When expressions such as “at least one of A, B, and C, etc.” are used, they should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art (for example, “a system having at least one of A, B, and C” should include but is not limited to systems having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, and C, etc.). When expressions such as “at least one of A, B, or C, etc.” are used, they should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art (for example, “a system having at least one of A, B, or C” should include but is not limited to systems having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, and C, etc.).

[0029] In view of this, in order to address the problem in the related art that quartz tubes are prone to cracking during use and have a short service life, the present application provides a quartz tube containing a porous coating and a preparation method thereof, so as to effectively extend the service life of the quartz tube.

[0030] Figure 1 Schematic diagram of a quartz tube containing a porous coating provided in an embodiment of the present application.

[0031] According to an exemplary embodiment of the present application, the present application provides a quartz tube containing a porous coating, with reference to Figure 1 As shown, it includes a quartz tube body 1 and a porous coating 2, wherein the porous coating 2 is located on the inner wall of the quartz tube body 1 and has a porous structure formed by stacking micro-nano particles. The "micro-nano particles" here refer to particles with a particle size at the micro or nano level.

[0032] According to the embodiments of the present application, due to the difference in thermal expansion coefficient between the quartz tube and the sediments, such as polysilicon, deposited on the inner wall of the quartz tube during operation, and the quartz tube itself, large thermal stress is generated. Repeated high-temperature cycles can cause the quartz tube to crack. As a result, a porous coating composed of stacked particles is formed on the inner wall of the quartz tube. During the use of the quartz tube, on the one hand, the porous structure of the stacked particles has good porosity, which can effectively buffer the thermal stress generated by the difference in thermal expansion coefficient between the quartz tube and the sediments. On the other hand, the porous structure of the stacked particles has a relatively stable three-dimensional spatial structure, which can provide good mechanical properties. When used as a buffer layer, it can effectively alleviate the cracking of the quartz tube and extend its service life.

[0033] In some embodiments, the porous coating 2 is made of a material selected from porous carbon, porous zirconium oxide, porous silicon carbide, porous silicon nitride, or porous silicon dioxide. These materials can be prepared by a sol-gel method to form a porous structure with accumulated micro-nano particles.

[0034] In some embodiments, the porous coating 2 is porous carbon. For example, the porous carbon coating is prepared by a sol-gel method. For example, polypyrrole, phenolic resin and other organic substances can be used as precursors, and acids such as hydrochloric acid, acetic acid, etc., or bases such as sodium carbonate, potassium hydroxide, etc. can be used as catalysts to prepare the porous carbon coating after condensation and carbonization.

[0035] In some embodiments, the porous coating 2 is porous zirconium oxide, for example, the porous zirconium oxide coating is prepared by a sol-gel phase separation method, and an organic zirconium salt such as zirconium propoxide or an inorganic zirconium salt such as zirconium oxychloride (ZrOCl2·8H2O) can be used as a precursor, and polyethylene oxide (PEO, Mv=10 6 ) or PEO as a phase separation inducer, water or ethanol as a solvent, and propylene oxide (PO) as a catalyst to prepare a porous zirconia coating.

[0036] In some embodiments, the porous coating 2 is porous silicon carbide, wherein phenolic resin or silicate is used as a precursor, nickel salt is used as a catalyst, and a sol-gel method is adopted to obtain the porous silicon carbide coating by high-temperature reduction.

[0037] In some embodiments, the porous coating 2 is porous silicon nitride, which is prepared using silicon nitride powder as raw material, water as solvent, magnesium hydroxide and / or ferric hydroxide as catalyst (also pore-forming agent), and a surfactant.

[0038] Compared to porous carbon coatings, porous zirconia coatings, porous silicon carbide coatings, porous silicon nitride coatings, and porous silica coatings can better bond to the quartz tube body, have more appropriate hardness and strength, can resist thermal stress, and improve the durability of the quartz tube. Compared to porous zirconia coatings, porous silicon carbide coatings, porous silicon nitride coatings, and porous silica coatings, porous carbon coatings are more flexible and can resist thermal stress, thereby improving the durability of the quartz tube.

[0039] In some embodiments, the porosity of the porous coating 2 is any value between 30% and 70%, for example, 30%, 40%, 45%, 50%, 60%, 70%, but not limited to the values listed. In some embodiments, the porosity of the porous coating can be further selected as any value between 60% and 65%, for example, 60%, 61%, 62%, 63%, 64%, 65%, but not limited to the values listed. If the porosity of the porous coating is too low, it will not be conducive to the performance of its buffering effect. If the porosity is too high, the strength is poor, and it is easy to crack or damage, which reduces its service life.

[0040] According to the embodiment of the present application, the method for estimating the porosity of the porous coating is not limited in this application, and those skilled in the art can measure it by conventional methods in the art. For example, 10 square areas of 5 cm wide can be randomly selected from different areas of the porous coating of the quartz tube obtained for confocal microscopy photography, photographed at the same magnification, and a 20 μm wide square area is selected. For particles and pores of different sizes and irregular shapes in the selected area, a grayscale method is used, and imagej software is used for processing and analysis, and the photo image is converted into a grayscale image so that different grayscale values represent different pore sizes or material densities. A suitable grayscale threshold is set to distinguish between pores and film matrix, and pores are identified using image processing software, and parameters such as their size and shape are measured. Finally, the pore parameters are statistically analyzed, and the porosity obtained is estimated by taking the average of the 10 groups of data obtained, with an error range of ± 5%. The electron microscope image in this application, in which the void is black, and the high-density bright color is not a void, belongs to a particle stacking structure.

[0041] In some embodiments, a quartz plate sample (quartz sample) made of the same material as the quartz tube body can be provided, and the above-mentioned porous coating can be prepared on the quartz sample. The porosity of the porous coating on the quartz sample can be estimated to obtain the porosity of the porous coating on the quartz tube body.

[0042] In some embodiments, the thickness of the porous coating is any value between 5 μm and 15 μm, for example, 5 μm, 8 μm, 10 μm, 12 μm, and 15 μm, but is not limited to these values. A porous coating that is too thick will not improve mechanical strength, will easily shed powder, and will have poor interfacial bonding with the quartz tube body, making it prone to cracking. A porous coating that is too thin will not be conducive to buffering the thermal stress release between the quartz tube body and the deposit.

[0043] According to the embodiment of the present application, the porous coating 2 located on the inner wall of the quartz tube body 1 is more conducive to the porous coating 2 being stably bonded to the inner wall of the quartz tube body 1 when meeting appropriate hardness and bonding strength, thereby further helping to improve the service life of the quartz tube.

[0044] Among them, the hardness and bonding strength of the porous coating 2 located on the inner wall of the quartz tube body 1 can be measured by using the pencil method according to GB / T 6739-2022 (full name: "Paints and varnishes - Determination of paint film hardness"). The hardness of the porous coating 2 can be measured using the pencil method, and the bonding strength of the porous coating on the inner wall of the quartz tube body can be measured according to the cross-cut test of GBT 9286-2021 (full name: "Paint and varnish film cross-cut test").

[0045] According to an embodiment of the present application, optionally, the pencil hardness of the porous coating 2 is greater than or equal to 3H and less than or equal to 7H, for example, it can be 3H, 4H, 5H, 6H, 7H, but is not limited to the listed values; for ease of measurement, the bonding force of the porous coating 2 on the quartz tube body 1 can be determined by forming a porous coating 2 of the same specification on a quartz sample. In the GBT 9286-2021 cross-cut test, the bonding force of the porous coating 2 on the quartz sample is level 0~1.

[0046] According to an embodiment of the present application, the size of the high-density particle accumulation area on the porous coating 2 is less than 50 μm, and preferably 90% of the high-density particle accumulation area is less than 30 μm. For example, the diagonal size of the high-density particle accumulation area is 30 μm, 25 μm, 20 μm, 15 μm, 10 μm, and 5 μm. By effectively controlling the size of the high-density particle accumulation area on the porous coating 2 within the above range, this solution can prevent the porous coating from breaking, enhance the buffering effect of the porous coating, and thus achieve the effect of preventing the quartz tube from breaking. The dimensions here also include side length, diameter, arc length, etc.

[0047] According to an embodiment of the present application, the maximum size of the high-density pore area in the porous coating is less than 80 μm. Preferably, 90% of the area size of the high-density pore area is less than 30 μm. For example, the diagonal size of the high-density pore area is 30 μm, 25 μm, 20 μm, 15 μm, 10 μm, and 5 μm. Through the above distribution, the distribution uniformity of high-density particles and high-density pores in the coating is improved, and the buffering effect is enhanced. The size here also includes side length, diameter, arc length, etc.

[0048] Figure 2 A schematic flow chart of a method for preparing a quartz tube containing a porous coating provided in an embodiment of the present application.

[0049] According to an exemplary embodiment of the present application, the present application provides a method for preparing a quartz tube containing a porous coating, referring to Figure 1 、 Figure 2 As shown, it includes: operation S1 to operation S2.

[0050] In operation S1 , the particle sol and the film-forming aid are mixed to obtain a film-forming precursor sol.

[0051] In some embodiments, the porous coating 2 is a porous silica coating. The particulate sol may include acidic silica sol and alkaline silica sol. Experiments have shown that by adjusting the mixing ratio of the acidic silica sol and the alkaline silica sol, porous silica coatings with varying porosities can be prepared, thereby preventing quartz tube cracking and extending the service life.

[0052] In some embodiments, the pH of the acidic silica sol can be any value between 1 and 2, for example, 1, 1.5, and 2, but not limited to the values listed above; and / or, the pH of the alkaline silica sol can be any value between 8 and 9, for example, 8, 8.5, and 9, but not limited to the values listed above.

[0053] According to the embodiments of the present application, the pH value of the sol will affect the progress of the hydrolysis reaction. Under acidic conditions, the hydrolysis reaction is slow, the stability of the sol is better, and it is more conducive to the formation of a coating containing smaller particles and low porosity. Under alkaline conditions, the hydrolysis reaction rate is fast, which is more conducive to the formation of a coating containing larger particles and high porosity.

[0054] In some embodiments, the volume ratio of the acidic silica sol to the alkaline silica sol may be 1:3 to 3:1, and may further be 1:2 to 2:1.

[0055] In some embodiments, the porous coating is a porous silica coating. Under alkaline catalysis, silica sol tends to form a granular structure, and the resulting film has a rough and porous surface; under acidic catalysis, silica sol tends to form a tangled or bifurcated linear chain structure, and the resulting film has a smooth surface and low porosity. If the ratio of acidic silica sol to alkaline silica sol is too high, the resulting porous coating has low porosity; if the ratio is too low, the resulting porous coating has high porosity but insufficient strength. In other words, a ratio that is too high or too low is not conducive to forming a porous coating with high porosity and high strength.

[0056] In some embodiments, acidic silica sol and alkaline silica sol can be prepared respectively using a precursor, a solvent, and a catalyst, wherein the volume ratio of the precursor, the solvent, and the catalyst is (1-3): (5-9): (0.01-0.02).

[0057] In some embodiments, the acidic silica sol is prepared. Specifically, the precursor, the solvent, and the acidic catalyst are mixed and stirred in a volume ratio of (1-3): (5-9): (0.01-0.02) to obtain the acidic silica sol.

[0058] In some embodiments, the precursor may include tetramethyl orthosilicate or tetraethyl orthosilicate.

[0059] In some embodiments, the solvent may include an organic solvent and water, and the organic solvent may include one or more of anhydrous ethanol, isopropyl alcohol, and ethylene glycol ethyl ether.

[0060] In some embodiments, the acidic catalyst may include nitric acid.

[0061] In some embodiments, an organic solvent and water are thoroughly mixed to obtain a first mixed solution. A precursor and an acidic catalyst are dropwise added to the first mixed solution and stirred for 1-2 hours. After thorough mixing, a first homogeneous solution is formed. The first homogeneous solution is heated and stirred in a water bath at 50°C-60°C for 24 hours. The resulting first homogeneous solution is allowed to stand at room temperature for 24 hours and then filtered to obtain an acidic silica sol.

[0062] In some embodiments, alkaline silica sol is prepared by mixing and stirring a precursor, a solvent, and an alkaline catalyst in a volume ratio of (1-3): (5-9): (0.01-0.02) to obtain alkaline silica sol.

[0063] In some embodiments, the basic catalyst comprises ammonia.

[0064] In some embodiments, an organic solvent and water are thoroughly mixed to obtain a second mixed solution. A precursor and an alkaline catalyst are dropwise added to the second mixed solution and stirred for 1-2 hours. After thorough mixing, a second homogeneous solution is formed. The second homogeneous solution is heated and stirred in a water bath at 50°C to 60°C for 24 hours. The resulting second homogeneous solution is allowed to stand at room temperature for 24 hours and then filtered to obtain an alkaline silica sol.

[0065] According to an embodiment of the present application, the acidic silica sol and the alkaline silica sol are uniformly mixed in proportion to prepare a granular sol.

[0066] In some embodiments, the film-forming aid may include at least one of a stabilizer, a silane coupling agent, and a leveling agent.

[0067] In some embodiments, the stabilizer may include DMF (N,N-dimethylformamide). The stabilizer is suitable for reducing the viscosity of the particle sol, improving the stability of the particle sol system, and prolonging the gel time.

[0068] In some embodiments, the silane coupling agent may include one or more of F-silane coupling agent (1H,1H,2H,2H-perfluorodecyltrimethoxysilane) and KH-560 (γ-glycidoxypropyltrimethoxysilane). The silane coupling agent is useful for improving the bonding strength between the porous coating and the quartz tube body, making the porous coating less susceptible to demolding.

[0069] In some embodiments, the leveling agent may include polyether-modified polydimethylsiloxane. The leveling agent can promote the flow and leveling of the particle sol without affecting the interlayer adhesion of the particle sol on the quartz tube body, and also has a defoaming effect.

[0070] In some more specific embodiments, the volume ratio of the precursor, organic solvent, water, catalyst, stabilizer, silane coupling agent, and leveling agent can be (1-3):(4-7):(1-2):(0.01-0.02):(0.1-0.25):(0.05-0.06):(0.005-0.04), for example, it can be expressed as (25-600):(100-1400):(25-400) : (0.25~4): (2.5~50): (1.25~12): 1, for example, it can be 200:420:72:3:35:3.5:1, 200:500:72:3:30:3:1, 50:125:250:2:50:5:1, 100:195:25:1:40:4:1, 100:350:50:1:50:5:1, but is not limited to the listed values.

[0071] In operation S2 , the film-forming precursor sol is sprayed onto the inner wall of the quartz tube body 1 and dried, and the quartz tube body 1 containing the porous coating 2 is obtained after heat treatment.

[0072] According to an embodiment of the present application, before the film-forming precursor sol is sprayed on the inner wall of the quartz tube body, a pH adjuster is used to adjust the pH value of the film-forming precursor sol to 1~3, for example, 1, 2, 3, but not limited to the values listed above; so that the film-forming precursor sol remains in a relatively stable and uniform state, and the film-forming precursor sol is prevented from agglomerating.

[0073] According to an embodiment of the present application, before spraying the film-forming precursor sol onto the inner wall of the quartz tube body, the quartz tube body is ultrasonically cleaned with distilled water, ultrasonically cleaned with anhydrous ethanol, and blown dry with a fan to remove impurities on the inner wall of the quartz tube body.

[0074] According to an embodiment of the present application, a film-forming precursor sol is sprayed onto the inner wall of a quartz tube body and dried, and the spraying and drying operations are repeated 30 to 50 times, for example, 30 times, 33 times, 35 times, 38 times, 40 times, 42 times, 45 times, 48 times, and 50 times, but not limited to these values. The appropriate number of repeated sprayings is conducive to forming a porous coating of appropriate thickness, thereby taking into account both the buffering effect and the improvement of mechanical strength.

[0075] In some embodiments, the temperature of the heat treatment is any value between 1000°C and 1100°C, for example, it can be 1000°C, 1020°C, 1050°C, 1080°C, 1100°C, but is not limited to the values cited. The time of the heat treatment is any value between 10min and 60min, for example, it can be 10min, 20min, 30min, 40min, 50min, 60min, but is not limited to the values cited. If the temperature of the heat treatment is too high, it is easy to cause the quartz tube body to crystallize, making the quartz tube brittle and prone to cracking; if the temperature of the heat treatment is too low, the bonding force between the porous coating 2 and the quartz tube body 1 is poor, and the porous coating 2 is prone to fall off. The heat treatment temperature is 1000°C to 1100°C, which can effectively combine the porous coating 2 with the quartz tube body 1 to achieve a buffering effect.

[0076] According to an embodiment of the present application, a porous coating 2 is formed on the inner wall of the quartz tube body 1 by a sol-gel method, and then a porous structure formed by stacking micro-nano particles is obtained by heat treatment.

[0077] The following schematically illustrates the designed quartz tube containing a porous coating and its preparation method. It should be noted that this example is only a specific embodiment of the present application and does not limit the scope of protection of the present application.

[0078] Example 1

[0079] The porous silica coating is prepared on the inner wall of the quartz tube body, including the following operations:

[0080] 1. Prepare the quartz tube body, ultrasonically clean it, and blow it dry for later use;

[0081] 2. Preparation of granular sol:

[0082] (1) Prepare acidic silica sol and alkaline silica sol respectively:

[0083] Prepare a first homogeneous solution. Specifically, thoroughly mix anhydrous ethanol and water to obtain a first mixed solution. Add tetraethyl orthosilicate (precursor) and nitric acid (acidic catalyst) dropwise to the first mixed solution and stir for 1 hour to allow thorough mixing to form a first homogeneous solution. The volume ratio of tetraethyl orthosilicate, anhydrous ethanol, water, and nitric acid in the first homogeneous solution is 200:420:72:3.

[0084] Prepare a second homogeneous solution. Specifically, thoroughly mix anhydrous ethanol and water to obtain a second mixed solution. Add tetraethyl orthosilicate (precursor) and aqueous ammonia (alkaline catalyst) dropwise to the second mixed solution and stir for 1 hour to allow thorough mixing to form a second homogeneous solution. The volume ratio of tetraethyl orthosilicate, anhydrous ethanol, water, and aqueous ammonia in the second homogeneous solution is 200:420:72:3.

[0085] The first homogeneous solution and the second homogeneous solution were placed in a 60°C water bath and heated with stirring for 24 hours.

[0086] After the reaction, the first homogeneous solution and the second homogeneous solution were placed at room temperature for aging for 24 hours, and filtered to obtain an acidic silica sol with a pH of about 1-2 and an alkaline silica sol with a pH of about 8-9, respectively.

[0087] (2) preparing a granular sol. Specifically, the obtained acidic silica sol and alkaline silica sol were mixed in a volume ratio of 2:1, and stirred for 1 hour to fully mix them to obtain a granular sol.

[0088] 3. Preparation of film precursor sol:

[0089] DMF, F-silane coupling agent and leveling agent were sequentially added dropwise to the obtained particle sol to obtain a film-forming precursor sol; wherein, as shown in Table 1, the volume ratio of tetraethyl orthosilicate, DMF: F-silane coupling agent: leveling agent was 200:35:3.5:1;

[0090] Nitric acid (as a pH adjuster) was added dropwise to the obtained film-forming precursor sol to adjust the pH to about 2.

[0091] Table 1

[0092]

[0093] 4. Preparation of quartz tube body with porous coating:

[0094] The quartz tube body was placed on a heating table, the temperature was set to 100°C, and the spraying process was used. The spraying distance was adjusted to 30 cm and the flow rate was set to 10 mL / min. The obtained film-forming precursor sol was evenly sprayed on the inner surface of the quartz tube body. After heating and drying for 1 minute, the spraying was repeated 40 times.

[0095] The quartz tube body after multiple spraying is placed in a high temperature heat treatment at 1050° C. for 30 minutes to obtain a porous silica coating.

[0096] Porosity estimation, hardness testing, and adhesion testing were performed on quartz samples containing porous silica coatings prepared using the same method as in Example 1. The pencil hardness test graded the film layers as follows: 9B-8B-…B-HB-FH-2H-…8H-9H, with 9B being the lowest and 9H being the highest, with the hardness increasing in this order. The cross-hatch method tested the film adhesion strength, with adhesion levels ranging from 0, 1, 2, 3, 4, and 5, with 0 being the strongest and adhesion decreasing from 0 to 5.

[0097] refer to Figure 3 、 Figure 12 As shown, Figure 3 The bright area is the area where high-density particles accumulate in the porous coating, and the dark area is the high-density pore area. The test results show that the hardness of the quartz sample with a porous silica coating containing a porosity of 36% reaches 5H, and the bonding strength of the porous coating on the quartz sample reaches level 1. This shows that the quartz tube containing a porous silica coating prepared in Example 1 has a suitable porosity as well as high hardness and bonding strength, and can effectively provide a buffering effect for the thermal stress generated by the difference in thermal expansion coefficient between the quartz tube body and the sediment.

[0098] Example 2

[0099] The preparation process of the porous silica coating on the inner wall of the quartz tube body is the same as that in Example 1, except that the organic solvent is isopropanol, the volume ratio of tetraethyl orthosilicate, isopropanol, water, and nitric acid in the first homogeneous solution is 200:500:72:3; the volume ratio of tetraethyl orthosilicate, isopropanol, water, and ammonia in the second homogeneous solution is 200:500:72:3; the volume ratio of acidic silica sol to alkaline silica sol is 1:2, and the film precursor sol is prepared according to the raw material ratio shown in Table 2.

[0100] Table 2

[0101]

[0102] The quartz sample containing the porous silica coating obtained by the same preparation method as in Example 2 was subjected to porosity estimation, hardness and bonding strength tests. Figure 4 、 Figure 12 As shown, Figure 4 The highlighted area is the area where high-density particles accumulate in the porous coating, and the dark area is the high-density pore area. The test results show that the hardness of the quartz sample with a porous silica coating containing a porosity of 70% reaches 4H, and the bonding strength of the porous coating on the quartz sample reaches level 2.5. This shows that the quartz tube containing a porous silica coating prepared in Example 2 has a suitable porosity and a high hardness. The bonding strength of the porous silica coating in Example 2 is lower than that in Example 1, but it can still meet the use requirements such as durability, and can effectively provide a buffering effect for the thermal stress generated by the difference in thermal expansion coefficient between the quartz tube body and the sediment.

[0103] Example 3

[0104] The preparation process of the porous silica coating on the inner wall of the quartz tube body is the same as that in Example 1, except that the organic solvents are anhydrous ethanol and isopropanol, the volume ratio of tetraethyl orthosilicate, anhydrous ethanol, isopropanol, water, and nitric acid in the first homogeneous solution is 50:62.5:62.5:250:2; the volume ratio of tetraethyl orthosilicate, anhydrous ethanol, isopropanol, water, and ammonia in the second homogeneous solution is 50:62.5:62.5:250:2; the volume ratio of acidic silica sol to alkaline silica sol is 1:1; and the film precursor sol is prepared according to the raw material ratio shown in Table 3.

[0105] Table 3

[0106]

[0107] The quartz sample containing the porous silica coating obtained by the same preparation method as in Example 3 was subjected to porosity estimation, hardness and bonding strength tests. Figure 5 、 Figure 12 As shown, Figure 5 The bright area is the area where high-density particles accumulate in the porous coating, and the dark area is the high-density pore area. The test results show that the hardness of the quartz sample with a porous silica coating containing a porosity of 62% reaches 6H, and the bonding force of the porous coating on the quartz sample reaches level 0, which shows that the quartz tube containing a porous silica coating prepared in Example 3 has a suitable porosity as well as high hardness and bonding force, and can effectively provide a buffering effect for the thermal stress generated by the difference in thermal expansion coefficient between the quartz tube body and the sediment.

[0108] Example 4

[0109] The preparation process of the porous silica coating on the inner wall of the quartz tube body is the same as that in Example 1, except that the organic solvents are anhydrous ethanol, isopropanol and ethanol diethyl ether, and the volume ratio of tetraethyl orthosilicate, anhydrous ethanol, isopropanol, ethanol diethyl ether, water, and nitric acid in the first homogeneous solution is 100:60:60:75:25:1; the volume ratio of tetraethyl orthosilicate, anhydrous ethanol, isopropanol, ethanol diethyl ether, water, and ammonia in the second homogeneous solution is 100:60:60:75:25:1; the volume ratio of acidic silica sol to alkaline silica sol is 1:1; and the film precursor sol is prepared according to the raw material ratio shown in Table 4.

[0110] Table 4

[0111]

[0112] The quartz sample containing the porous silica coating obtained by the same preparation method as in Example 4 was subjected to porosity estimation, hardness and bonding strength tests. Figure 6 、 Figure 12 As shown, Figure 6 The bright area is the area where high-density particles accumulate in the porous coating, and the dark area is the high-density pore area. The test results show that the hardness of the quartz sample with a porous silica coating of 51% reaches 5H, and the bonding strength of the porous coating on the quartz sample reaches level 2, which shows that the quartz tube containing a porous silica coating prepared in Example 4 has a suitable porosity as well as high hardness and bonding strength, and can effectively provide a buffering effect for the thermal stress generated by the difference in thermal expansion coefficient between the quartz tube body and the sediment.

[0113] Example 5

[0114] The preparation process of the porous silica coating on the inner wall of the quartz tube body is the same as that in Example 1, except that the organic solvents are anhydrous ethanol and isopropanol, the volume ratio of tetraethyl orthosilicate, anhydrous ethanol, isopropanol, water, and nitric acid in the first homogeneous solution is 100:150:200:50:1; the volume ratio of tetraethyl orthosilicate, anhydrous ethanol, isopropanol, water, and ammonia in the second homogeneous solution is 100:150:200:50:1; the volume ratio of acidic silica sol to alkaline silica sol is 2:1; and the film precursor sol is prepared according to the raw material ratio shown in Table 5.

[0115] Table 5

[0116]

[0117] The quartz sample containing the porous silica coating obtained by the same preparation method as in Example 5 was subjected to porosity estimation, hardness and bonding strength tests. Figure 7 、 Figure 12As shown, Figure 7 The bright area is the area where high-density particles accumulate in the porous coating, and the dark area is the high-density pore area. The test results show that the hardness of the quartz sample with a porous silica coating of 43% reaches 5H, and the bonding strength of the porous coating on the quartz sample reaches level 1, which shows that the quartz tube containing a porous silica coating prepared in Example 5 has a suitable porosity as well as high hardness and bonding strength, and can effectively provide a buffering effect for the thermal stress generated by the difference in thermal expansion coefficient between the quartz tube body and the sediment.

[0118] Example 6

[0119] The preparation process of the porous silica coating on the inner wall of the quartz tube body is the same as that of Example 3, except that the volume ratio of the acidic silica sol to the alkaline silica sol is 1:3; and the membrane precursor sol is prepared according to the raw material ratio shown in Table 6.

[0120] Table 6

[0121]

[0122] The quartz sample containing the porous silica coating obtained by the same preparation method as in Example 6 was subjected to porosity estimation, hardness and bonding strength tests. Figure 8 、 Figure 12 As shown, Figure 8 The bright area is the area where high-density particles accumulate in the porous coating, and the dark area is the high-density pore area. The test results show that the hardness of the quartz sample with a porous silica coating containing a porosity of 73% reaches 5H, and the bonding strength of the porous coating on the quartz sample reaches level 2, which indicates that the quartz tube containing a porous silica coating prepared in Example 6 has a higher hardness, and the bonding strength between the porous silica coating and the battery body is moderate. During the operation of the quartz tube, it can effectively provide a buffering effect for the thermal stress generated by the difference in thermal expansion coefficient between the quartz tube body and the sediment.

[0123] Example 7

[0124] The preparation process of the porous silica coating on the inner wall of the quartz tube body is the same as that of Example 3, except that the volume ratio of the acidic silica sol to the alkaline silica sol is 3:1; and the membrane precursor sol is prepared according to the raw material ratio shown in Table 7.

[0125] Table 7

[0126]

[0127] The quartz sample containing the porous silica coating obtained by the same preparation method as in Example 7 was subjected to porosity estimation, hardness and bonding strength tests. Figure 9 、 Figure 12 As shown, Figure 9 The bright area is the area where high-density particles accumulate in the porous coating, and the dark area is the high-density pore area. The test results show that the hardness of the quartz sample with a porous silica coating containing a porosity of 21% reaches 4H, and the bonding strength of the porous coating on the quartz sample reaches level 3, which indicates that the porous silica coating prepared in Example 7 has a relatively suitable hardness, the bonding strength between the porous silica coating and the battery body is moderate, and the porosity of the porous silica coating is relatively low, which basically meets the requirement of providing a buffering effect between the quartz tube body and the sediment.

[0128] Comparative Example 1

[0129] The acidic silica sol was prepared in the same manner as in Example 3. The acidic silica sol was directly used as the particle sol and the membrane precursor sol was prepared according to the raw material ratio shown in Table 8.

[0130] Table 8

[0131]

[0132] The porosity estimation, hardness and bonding strength tests were performed on the quartz sample containing the porous silica coating obtained by the same preparation method as in Comparative Example 1. Figure 10 、 Figure 12 As shown, Figure 10 The bright area is the area where high-density particles accumulate in the porous coating, and the dark area is the high-density pore area. The test results show that the hardness of the quartz sample with a porous silica coating containing a porosity of 15% reaches 5.5H, and the bonding strength of the porous coating on the quartz sample reaches level 1, which indicates that the quartz tube containing a porous silica coating prepared in Comparative Example 1 has a more suitable hardness and bonding strength, but the porosity of the porous silica coating is too low and relatively dense, making it difficult to effectively provide a buffering effect for the thermal stress generated by the difference in thermal expansion coefficient between the quartz tube body and the sediment.

[0133] Comparative Example 2

[0134] The alkaline silica sol was prepared in the same manner as in Example 1. The alkaline silica sol was directly used as the particle sol and the membrane precursor sol was prepared according to the raw material ratio shown in Table 9.

[0135] Table 9

[0136]

[0137] The quartz sample containing porous silica coating obtained by the same preparation method as in Comparative Example 2 was subjected to porosity estimation, hardness and bonding strength tests. Figure 11 、 Figure 12As shown in FIG, the test results show that the hardness of the quartz sample with a porous silica coating having a porosity of 79% reaches 4H, and the bonding strength of the porous coating on the quartz sample is level 4, which indicates that the quartz tube with a porous silica coating prepared in Comparative Example 2 has a relatively suitable hardness, but the porosity of the porous silica coating is too high, the strength of the porous silica coating is relatively poor, the surface is easily damaged, and the bonding strength level is low; Figure 11 The porous morphology shown is non-uniformly distributed, which makes it difficult to effectively provide a buffer for the thermal stress generated by the difference in thermal expansion coefficient between the quartz tube body and the sediment.

[0138] The test results of the above embodiments and comparative examples are described as follows:

[0139] Table 10

[0140]

[0141] According to the above-mentioned embodiments and comparative examples of the present application, by regulating the proportion of reactants, the type of reaction solvent and the acid-base sol ratio, a porous silica coating with adjustable porosity, good mechanical properties and excellent bonding properties can be obtained. The porous silica coating serves as a buffer layer between the quartz tube body and the deposited polysilicon, which can effectively alleviate the problem of easy cracking of the quartz tube during operation due to the difference in thermal expansion coefficients between the polysilicon and the quartz tube body, thereby extending its service life.

[0142] Among them, compared with the use of acid sol alone in Comparative Example 1, Examples 1 to 7 use different raw material ratios and acid-base sol ratios, so that the porosity of the prepared porous silica coating is significantly improved, and the hardness and bonding strength meet the durability requirements, which can effectively play a buffering role and extend the service life; compared with the use of alkali sol alone in Comparative Example 2, the porosity of the porous silica coating prepared in Examples 1 to 7 is reduced, and it is not easy to be damaged and the strength is too low, and the hardness is equivalent to or improved, and the bonding strength is also improved. The hardness and bonding strength meet the durability requirements, which can effectively play a buffering role and extend the service life.

[0143] It is worth mentioning that the porous silica coating with a porosity of 62% prepared in Example 3 has an appropriate porosity, better mechanical properties and bonding strength, and is more effective in protecting the quartz tube from cracking. A comparison of Examples 6 to 7 with Examples 1 to 5 shows that the main difference lies in the different ratios of acid and base sols. The porosity of Examples 1 to 5 is more suitable for use as a buffer layer than that of Examples 6 to 7, and the hardness and bonding strength are comparable or even better. It can be seen that a volume ratio of acidic silica sol to alkaline silica sol of 1:2 to 2:1 is more preferred.

[0144] The use of ordinal numbers such as "first," "second," and "third" in the specification and claims to modify corresponding elements does not in itself mean that the elements have any ordinal number, nor does it represent the order of one element relative to another or the order in the manufacturing method. The use of such ordinal numbers is only used to clearly distinguish one element with a certain name from another element with the same name.

[0145] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of this application. It should be understood that the above is only a specific embodiment of this application and is not intended to limit this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this application.

Claims

1. A quartz tube comprising: Quartz tube body; as well as The porous coating is located on the inner wall of the quartz tube body, and the porous coating has a porous structure formed by stacking micro-nano particles.

2. The quartz tube according to claim 1, wherein The material of the porous coating is selected from porous carbon, porous zirconia, porous silicon carbide, porous silicon nitride or porous silicon dioxide.

3. The quartz tube according to claim 1 or 2, wherein: The porosity of the porous coating layer is 30% to 70%, more preferably 60% to 65%.

4. The quartz tube according to claim 1 or 2, wherein: The thickness of the porous coating layer is 5-15 μm.

5. The quartz tube according to claim 1, wherein The size of the high-density particle accumulation region on the porous coating is less than 50 μm, and preferably, 90% of the high-density particle accumulation region has a size less than 30 μm. The quartz tube according to claim 1 , wherein: The maximum size of the high-density pore region in the porous coating is less than 80 μm. Preferably, 90% of the high-density pore region has a size less than 30 μm.

7. A method for preparing a quartz tube, comprising: mixing the particle sol and the film-forming aid to obtain a film-forming precursor sol; The film-forming precursor sol is sprayed on the inner wall of the quartz tube body and dried, and the quartz tube body containing the porous coating is obtained after heat treatment.

8. The preparation method according to claim 7, wherein The particle sol includes acidic silica sol and alkaline silica sol.

9. The preparation method according to claim 8, wherein The volume ratio of the acidic silica sol to the alkaline silica sol is 1:3 to 3:1, preferably 1:2 to 2:

1.

10. The preparation method according to claim 7, wherein The granular sol is prepared by the following method: The precursor, the solvent and the catalyst are mixed and stirred according to a volume ratio of (1-3): (5-9): (0.01-0.02) to obtain the particle sol.

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