A coating, a quartz tube containing the same, and applications thereof

Abstract

The present invention provides a coating, a quartz tube containing the same, and applications thereof. The coating comprises 90 to 110 parts of inorganic fine powder, 140 to 160 parts of water, 1 to 2 parts of a thickening agent, 2.5 to 4 parts of a high-temperature binder, and 1.5 to 3 parts of a foaming agent. The quartz tube of the present invention comprises a quartz tube and a porous coating provided on the inner wall of the quartz tube, and the raw material of the porous coating comprises the above-mentioned coating. The coating in the present invention has the advantages of high temperature resistance, uniform pores, high viscosity, and high adhesion. The coating cured by the coating of the present invention has a porous structure, which can effectively reduce the stress difference caused by the difference in expansion coefficients, thereby improving the thermal shock performance of the coating.

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaic materials, relates to a coating, and particularly relates to a coating, a quartz tube containing the same, and an application thereof. Background Art

[0002] In the processing of photovoltaic material semiconductors, the LPCVD (Low Pressure Chemical Vapor Deposition) equipment is a vacuum high-temperature furnace. As the cavity material of the vacuum furnace, the quartz furnace tube has the advantages of high temperature resistance, good light transmittance, and good thermal stability. During the operation of the LPCVD equipment, the gas-phase deposits will erode and damage the quartz furnace tube, thereby greatly reducing the service life of the furnace tube. This not only increases the production cost, but also the damaged quartz furnace tube may damage the furnace body structure, causing greater losses and risks.

[0003] Therefore, improving the life of the quartz furnace tube can generate significant economic value and enhance the core competitiveness of the enterprise. At present, the research directions for improving the life of the quartz furnace tube mainly focus on two aspects: functional coatings and double-layer structures.

[0004] The functional coating of the quartz tube is mainly determined by the components of the coating. The quartz tube is often used for high-temperature calcination. Therefore, the coating needs to have good high-temperature resistance. The coating with high-temperature resistance has low thermal conductivity, which can effectively prevent damage to the substrate material at high temperatures.

[0005] Currently, the commonly used high-temperature resistant coatings mainly include organic high-temperature resistant coatings and inorganic high-temperature resistant coatings. However, most high-temperature resistant coatings are applied in static high-temperature environments. When used in high-temperature dynamic environments, cracks will appear on the surface of the coating obtained by curing the coating, resulting in problems such as cracking, peeling, and fracture.

[0006] Therefore, how to prepare a coating that can be cured into a coating with good thermal shock resistance is an important research direction in this field. Summary of the Invention

[0007] The purpose of the present invention is to provide a coating, a quartz tube containing the same, and an application thereof. The coating in the present invention has the advantages of high temperature resistance, uniform pores, high viscosity, high curing strength, and high adhesion. The coating obtained by curing the coating of the present invention has a porous structure, which can effectively reduce the stress difference caused by the difference in expansion coefficients, thereby improving the thermal shock performance of the coating.

[0008] To achieve the purpose of this invention, the following technical solutions are adopted in the present invention:

[0009] One of the purposes of the present invention is to provide a coating, which includes 90-110 parts of inorganic fine powder, 140-160 parts of water, 1-2 parts of thickener, 2.5-4 parts of high-temperature binder, and 1.5-3 parts of foaming agent.

[0010] Among them, the number of parts of the inorganic fine powder can be 90 parts, 92 parts, 94 parts, 96 parts, 98 parts, 100 parts, 102 parts, 104 parts, 106 parts, 108 parts or 110 parts, etc., and the number of parts of water can be 140 parts, 142 parts, 144 parts, 146 parts, 148 parts, 150 parts, 152 parts, 154 parts, 156 parts, 158 parts or 160 parts, etc. Among them, the number of parts of the thickener can be 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts or 2 parts, etc., and the number of parts of the high-temperature binder can be 2.5 parts, 2.8 parts, 3.0 parts, 3.2 parts, 3.4 parts, 3.6 parts, 3.8 parts or 4 parts, etc. Among them, the number of parts of the foaming agent can be 1.5 parts, 1.8 parts, 2.0 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts or 3 parts, etc., but not limited to the listed values. Other unlisted numerical ranges within the above numerical ranges are equally applicable.

[0011] The coating in the present invention has the advantages of high temperature resistance, uniform pores, high viscosity and high adhesion. At the same time, the coating obtained after the coating in the present invention is cured can be a coating with a porous structure. The porous structure of the porous coating can effectively reduce the stress difference caused by the difference in expansion coefficients, thereby improving the thermal shock performance of the coating.

[0012] In the present invention, the ratio of the inorganic fine powder to the foaming agent affects the size and number of pores in the coating. If the ratio of the foaming agent in the present invention is too high, there will be many pores and large pore diameters in the pores of the prepared coating, the pores are uneven, and even the pores are broken to form gaps; if the ratio of the foaming agent in the present invention is too small, the pores in the prepared coating are few and the pore diameters are small, and even there is a problem of partial unfoamed structure.

[0013] In the present invention, the high-temperature binder is related to the sintering process of the coating. If the content of the added high-temperature binder is too high, it will increase the cost of coating preparation, and the coating obtained after coating curing will have the risk of cracking and peeling. If the content of the added high-temperature binder is too small, the curing strength of the inorganic fine powder is low, or it cannot be cured, and the phenomenon of inorganic fine powder falling off is likely to occur during the coating curing process.

[0014] In the present invention, the ratio of the thickener to water is used to affect the viscosity and solid content of the coating, and further affect the spraying construction of the coating and the adhesion between the coating and the quartz tube wall after spraying. Therefore, on the basis of ensuring a certain solid content, by adjusting the ratio of the thickener, the viscosity of the coating can be adjusted. If the ratio of the thickener is too high, the coating viscosity is too high, and it cannot be atomized well to form a uniform coating. If the thickener is too little, the coating viscosity is too low, then the coating cannot adhere well to the tube wall, and even the flow of the coating will occur.

[0015] As a preferred technical solution of the present invention, the inorganic micropowders include silica powder, alumina powder, talc powder, feldspar powder and broken glass.

[0016] Preferably, the mass ratio of the silica powder, alumina powder, talc powder, feldspar powder and broken glass is

[0017] (20~40):(14~26):(5~10):(12~16):(25~35), where the mass ratio can be 30:26:5:14:25, 30:20:10:15:25, 35:18:5:12:30 or 40:18:5:12:25, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0018] Preferably, the thickener includes any one or a combination of at least two of polyacrylamide, hydroxypropyl methylcellulose or carboxymethylcellulose. Typical but non-limiting examples of the combination are: the combination of polyacrylamide and hydroxypropyl methylcellulose, the combination of hydroxypropyl methylcellulose and carboxymethylcellulose, or the combination of polyacrylamide and carboxymethylcellulose, etc.

[0019] Preferably, the high-temperature binder includes any one or a combination of at least two of silica sol, phosphoric acid solution or aluminum dihydrogen phosphate. Typical but non-limiting examples of the combination are: the combination of silica sol and phosphoric acid solution, the combination of phosphoric acid solution and aluminum dihydrogen phosphate, or the combination of silica sol and aluminum dihydrogen phosphate, etc.

[0020] Preferably, the foaming agent includes any one or a combination of at least two of calcium carbonate, sodium carbonate or silicon carbide. Typical but non-limiting examples of the combination are: the combination of heavy calcium powder and soda ash, the combination of soda ash and silicon carbide, or the combination of heavy calcium powder and silicon carbide, etc.

[0021] The second object of the present invention is to provide a quartz tube, which includes a quartz tube and a porous coating provided on the inner wall of the quartz tube.

[0022] The raw materials of the porous coating include the coating as described in the first object.

[0023] In order to improve the thermal shock performance of the coating and prevent the coating from peeling off at high temperatures, a coating containing a foaming agent is added during the preparation of the porous coating. The porous structure of the coating can effectively reduce the stress difference caused by the difference in expansion coefficients between the coating and the quartz tube, thereby improving the thermal shock performance of the coating. The porous coating can also effectively block the erosion of sediments and improve the average service life of the quartz tube. In addition, the presence of the porous coating significantly reduces the heat dissipation of the furnace, achieving the purpose of reducing heat loss and realizing energy conservation and emission reduction.

[0024] As a preferred technical solution of the present invention, the thickness of the porous coating is 0.3 - 1.0 mm. The thickness can be 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0025] Preferably, the pore diameter of the porous coating is 0.3 - 1.0 mm. The pore diameter can be 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0026] The pores of the porous coating in the present invention are a closed pore structure with uniform size.

[0027] The third object of the present invention is to provide a method for preparing a quartz tube as described in the second object. The preparation method includes:

[0028] Disperse the raw materials of the porous coating to obtain a coating material, spray the coating material on the inner wall of the quartz tube, and obtain the quartz tube through drying and sintering;

[0029] The raw materials of the porous coating include inorganic micropowders, water, thickeners, high-temperature binders, and foaming agents.

[0030] In the present invention, by adding a foaming agent and controlling the sintering temperature, a lightweight and porous coating structure is prepared, which can effectively relax the stress difference caused by different expansion coefficients.

[0031] As a preferred technical solution of the present invention, the preparation method of the coating material includes: after preparing the inorganic micropowders into an inorganic micropowder slurry, then dispersing it with a thickener, a high-temperature binder, and a foaming agent.

[0032] Preferably, the preparation method of the inorganic micropowder slurry includes: ball-milling inorganic micropowders, grinding balls, and water to obtain the inorganic micropowder slurry.

[0033] Preferably, the mass ratio of the inorganic fine powder, the grinding balls, and water is 1:(0.8~1.2):(1.2~1.7), where the mass ratio can be 1:0.8:1.2, 1:0.8:1.3, 1:0.8:1.4, 1:0.8:1.5, 1:0.8:1.6, 1:0.8:1.7, 1:1.0:1.2, 1:1.0:1.3, 1:1.0:1.4, 1:1.0:1.5, 1:1.0:1.6, 1:1.0:1.7, 1:1.2:1.2, 1:1.2:1.3, 1:1.2:1.4, 1:1.2:1.5, 1:1.2:1.6, or 1:1.2:1.7, etc., but not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0034] Preferably, the ball milling time is 6~8h, where the time can be 6h, 6.2h, 6.4h, 6.6h, 6.8h, 7.0h, 7.2h, 7.4h, 7.6h, 7.8h, or 8h, etc., but not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0035] As a preferred technical solution of the present invention, the spraying thickness is 0.3~1mm, where the thickness can be 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1 mm, etc., but not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0036] If the spraying thickness of the coating of the present invention is too thick, a three-dimensional structure will be formed, which will have an adverse effect on the temperature rise and fall of the quartz tube, and further cause a large difference in thermal stress, damaging the quartz tube; if the spraying thickness of the coating is too thin, the coating distribution will be uneven, resulting in the phenomenon of coating missing or excessive accumulation, reducing the protective effect of the coating.

[0037] Preferably, the drying time is 2.5~3.5h, where the time can be 2.5h, 2.6h, 2.7h, 2.8h, 2.9h, 3.0h, 3.1h, 3.2h, 3.3h, 3.4h, or 3.5h, etc., but not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0038] Preferably, the drying temperature is 10~35°C, where the temperature can be 10°C, 12°C, 14°C, 16°C, 18°C, 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C, or 35°C, etc., but not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0039] As a preferred technical solution of the present invention, the sintering includes one-stage sintering, two-stage sintering, and three-stage sintering that are carried out in sequence.

[0040] In the present invention, the sintering is divided into three stages. The first stage is to remove moisture and a small amount of organic matter. The second stage is for the binder and the fine powder to crystallize and solidify. The third stage is to induce the blowing agent to generate gas, and at this temperature, the coating has a certain viscosity to wrap the gas and form a closed structure.

[0041] Preferably, the heating rate of the one-stage sintering is 5 - 8 °C / min. The heating rate can be 5 °C / min, 6 °C / min, 7 °C / min, 8 °C / min, etc., but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0042] Preferably, the temperature of the one-stage sintering is 100 - 140 °C. The temperature can be 100 °C, 105 °C, 110 °C, 115 °C, 120 °C, 125 °C, 130 °C, 135 °C, 140 °C, etc., but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0043] Preferably, the holding time of the one-stage sintering is 25 - 35 mins. The holding time can be 25 mins, 26 mins, 27 mins, 28 mins, 29 mins, 30 mins, 31 mins, 32 mins, 33 mins, 34 mins, 35 mins, etc., but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0044] Preferably, the heating rate of the two-stage sintering is 8 - 10 °C / min. The heating rate can be 8 °C / min, 9 °C / min, 10 °C / min, etc., but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0045] Preferably, the temperature of the two-stage sintering is 350 - 400 °C. The temperature can be 350 °C, 360 °C, 370 °C, 380 °C, 390 °C, 400 °C, etc., but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0046] Preferably, the holding time of the second-stage sintering is 15 - 25 mins. The holding time can be 15 mins, 16 mins, 17 mins, 18 mins, 19 mins, 20 mins, 21 mins, 22 mins, 23 mins, 24 mins, or 25 mins, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0047] Preferably, the heating rate of the third-stage sintering is 5 - 8 °C / min. The heating rate can be 5 °C / min, 6 °C / min, 7 °C / min, or 8 °C / min, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0048] Preferably, the temperature of the third-stage sintering is 1100 - 1200 °C. The temperature can be 1100 °C, 1110 °C, 1120 °C, 1130 °C, 1140 °C, 1150 °C, 1160 °C, 1170 °C, 1180 °C, 1190 °C, or 1200 °C, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0049] Preferably, the holding time of the third-stage sintering is 15 - 25 mins. The holding time can be 15 mins, 16 mins, 17 mins, 18 mins, 19 mins, 20 mins, 21 mins, 22 mins, 23 mins, 24 mins, or 25 mins, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0050] Preferably, after sintering, it is naturally cooled to room temperature to obtain the quartz tube.

[0051] As a preferred technical solution of the present invention, the preparation method includes:

[0052] The raw materials of the porous coating are dispersed to obtain a coating material, and the coating material is sprayed on the inner wall of the quartz tube, and the spraying thickness is 0.3 - 1 mm;

[0053] The porous coating quartz tube is obtained through drying at room temperature for 2.5 - 3.5 h and successively performing first-stage sintering, second-stage sintering, and third-stage sintering. Among them, the heating rate of the first-stage sintering is 5 - 8 °C / min, the temperature is 100 - 140 °C, and the holding time is 25 - 35 mins; the heating rate of the second-stage sintering is 8 - 10 °C, the temperature is 350 - 400 °C, and the holding time is 15 - 25 mins; the heating rate of the third-stage sintering is 5 - 8 °C, the temperature is 1100 - 1200 °C, and the holding time is 15 - 25 mins.

[0054] A third object of the present invention is to provide an application of a coating as described in the first object, and the coating is applied in the field of photovoltaic materials.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (1) The coating in the present invention has the advantages of high temperature resistance, uniform pores, high viscosity and high adhesion. The coating obtained by curing the coating of the present invention has a porous structure, which can effectively reduce the stress difference caused by the difference in expansion coefficient, thereby improving the thermal shock performance of the coating;

[0057] (2) The present invention provides a porous coating quartz tube with good high temperature resistance, corrosion resistance and thermal shock performance. The porous structure of the coating can effectively reduce the stress difference caused by the difference in expansion coefficient between the coating and the quartz tube, thereby improving the thermal shock performance of the coating. Moreover, the porous coating quartz tube of the present invention can significantly reduce the heat dissipation of the furnace. During the heating and intermittent use of the quartz tube multiple times, the quartz tube can achieve the heat preservation effect, so that the heat loss can be reduced during continuous use, and the purpose of energy conservation and emission reduction can be achieved;

[0058] (3) The heat resistance of the porous coating quartz tube of the present invention can be as high as above 1000 °C. The porous coating quartz tube is heated to 800 °C, taken out and quickly cooled to room temperature after being kept warm for 20 minutes, and the operation is repeated 5 times, and there is no peeling, cracking or delamination of the coating; in addition, the porous coating quartz tube can effectively block the erosion of sediments, and the service life is longer than 60 days. Description of the Drawings

[0059] Figure 1 It is a coating morphology diagram of the porous coating quartz tube in Example 1 of the present invention.

[0060] Figure 2 It is a coating morphology diagram of the porous coating quartz tube in Example 2 of the present invention.

[0061] Figure 3 It is a coating morphology diagram of the porous coating quartz tube in Example 3 of the present invention.

[0062] Figure 4 It is a coating morphology diagram of the porous coating quartz tube in Example 4 of the present invention.

[0063] Figure 5 It is a coating morphology diagram of the porous coating quartz tube in Example 6 of the present invention.

[0064] Figure 6 It is a coating morphology diagram of the porous coating quartz tube in Example 8 of the present invention.

[0065] Figure 7It is the coating morphology diagram of the porous coated quartz tube in Embodiment 10 of the present invention.

[0066] Figure 8 It is the coating morphology diagram of the porous coated quartz tube in Embodiment 11 of the present invention.

[0067] Figure 9 It is the coating morphology diagram of the porous coated quartz tube in Comparative Example 1 of the present invention. Detailed implementation manners

[0068] The technical solution of the present invention will be further described below through specific implementation manners. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0069] Embodiment 1

[0070] This embodiment provides a preparation method of a porous coated quartz tube. The preparation method includes:

[0071] I. Preparation of inorganic micropowder slurry

[0072] Weigh the raw materials according to the specifications in Table 1.1. After mixing them evenly to obtain inorganic micropowder, reserve it for later use.

[0073] Table 1.1

[0074]

[0075] Pour the mixture of the above inorganic micropowder into a stainless steel ball milling tank. Add 1.5 kg of water and 5 kg of stainless steel balls in sequence. Ball mill at a rotation speed of 70 r / mins for 8 h. Take out the slurry and pass it through a 600-mesh sieve to obtain inorganic micropowder slurry.

[0076] II. Preparation of coating

[0077] Add hydroxypropyl methylcellulose, silica sol, aluminum dihydrogen phosphate solution and calcium carbonate to the inorganic micropowder slurry and stir evenly with an automatic stirrer to obtain a coating. The addition amounts of various additives are shown in Table 1.2.

[0078] Table 1.2

[0079]

[0080] III. Preparation of porous coated quartz tube

[0081] Take 300 ml of the coating material, atomize and granulate it using a high-pressure sprayer, and evenly spray it on the inner wall of the quartz tube. After spraying, control the thickness of the coating to 0.6 mm. After drying, sinter it. Raise the temperature to 120 °C at a heating rate of 8 °C / min, hold for 30 min for the first-stage sintering, then raise the temperature to 380 °C at a heating rate of 8 °C / min, hold for 20 min for the second-stage sintering, and finally raise the temperature to 1180 °C at a heating rate of 5 °C / min, hold for 20 min for the third-stage sintering. Subsequently, turn off the power supply and let the quartz tube cool naturally with the sintering furnace to room temperature, and then take out the porous-coated quartz tube. The coating morphology diagram of the porous-coated quartz tube in this example is as shown in Figure 1 shown.

[0082] Example 2

[0083] This example provides a method for preparing a porous-coated quartz tube, and the preparation method includes:

[0084] I. Preparation of inorganic micro-powder slurry

[0085] Weigh the raw materials according to the specifications in Table 2.1, mix them evenly to obtain inorganic micro-powder, and set aside.

[0086] Table 2.1

[0087]

[0088] Pour the mixture of the above inorganic micro-powder into a stainless steel ball milling tank, add 1.5 kg of water and 5 kg of stainless steel balls in sequence, mill at a rotation speed of 70 r / mins for 8 h, take out the slurry, and pass it through a 600-mesh sieve to obtain the inorganic micro-powder slurry.

[0089] II. Preparation of the coating material

[0090] Add hydroxypropyl methylcellulose, silica sol, phosphoric acid solution and calcium carbonate to the inorganic micro-powder slurry and stir evenly with an automatic stirrer to obtain the coating material. Among them, the addition amounts of various additives are shown in Table 2.2.

[0091] Table 2.2

[0092]

[0093] III. Preparation of the porous-coated quartz tube

[0094] Take 300 ml of the coating material, atomize and granulate it using a high-pressure sprayer, and evenly spray it on the inner wall of the quartz tube. After spraying, control the thickness of the coating to 0.3 mm. After drying, perform sintering. Raise the temperature to 100 °C at a heating rate of 5 °C / min, hold for 30 min for the first-stage sintering, then raise the temperature to 350 °C at a heating rate of 9 °C / min, hold for 20 min for the second-stage sintering, and finally raise the temperature to 1100 °C at a heating rate of 6 °C / min, hold for 20 min for the third-stage sintering. Subsequently, turn off the power supply, let the quartz tube cool naturally with the sintering furnace to room temperature, and then take out the porous-coated quartz tube. The coating morphology diagram of the porous-coated quartz tube in this example is as shown in Figure 2 shown.

[0095] Example 3

[0096] This example provides a method for preparing a porous-coated quartz tube, and the preparation method includes:

[0097] I. Preparation of inorganic micro-powder slurry

[0098] Weigh the raw materials according to the specifications in Table 3.1, mix them evenly to obtain inorganic micro-powder, and set it aside.

[0099] Table 3.1

[0100]

[0101] Pour the mixture of the above inorganic micro-powder into a stainless steel ball mill tank, add 1.5 kg of water and 5 kg of stainless steel balls in sequence, ball mill at a rotation speed of 70 r / mins for 8 h, take out the slurry, and pass it through a 600-mesh sieve to obtain the inorganic micro-powder slurry.

[0102] II. Preparation of the coating material

[0103] Add hydroxypropyl methylcellulose, silica sol, phosphoric acid solution, and calcium carbonate to the inorganic micro-powder slurry, and stir evenly with an automatic stirrer to obtain the coating material. Among them, the addition amounts of various additives are shown in Table 3.2.

[0104] Table 3.2

[0105]

[0106] III. Preparation of the porous-coated quartz tube

[0107] Take 300 ml of the coating material, atomize and granulate it using a high-pressure sprayer, and evenly spray it on the inner wall of the quartz tube. After spraying, control the thickness of the coating to 1.0 mm. After drying, perform sintering. Raise the temperature to 140 °C at a heating rate of 8 °C / min, hold for 30 min for the first-stage sintering, then raise the temperature to 400 °C at a heating rate of 10 °C / min, hold for 20 min for the second-stage sintering, and finally raise the temperature to 1200 °C at a heating rate of 8 °C / min, hold for 20 min for the third-stage sintering. Subsequently, turn off the power supply and let the quartz tube cool down to room temperature naturally with the sintering furnace, and then take out the porous-coated quartz tube. The coating morphology diagram of the porous-coated quartz tube in this example is as shown in Figure 3 shown.

[0108] Example 4

[0109] In this example, except that the thickness of the sprayed coating is controlled to 0.1 mm instead of 0.6 mm, other conditions are the same as those in Example 1. The coating morphology diagram of the porous-coated quartz tube in this example is as shown in Figure 4 shown.

[0110] Example 5

[0111] In this example, except that the thickness of the sprayed coating is controlled to 1.2 mm instead of 0.6 mm, other conditions are the same as those in Example 1.

[0112] Example 6

[0113] In this example, except that the sintering method is replaced by raising the temperature to 1180 °C at a heating rate of 5 °C / min and sintering for 20 min, other conditions are the same as those in Example 1. The coating morphology diagram of the porous-coated quartz tube in this example is as shown in Figure 5 shown.

[0114] Example 7

[0115] In this example, except that the sintering method is replaced by raising the temperature to 120 °C at a heating rate of 8 °C / min, holding for 30 min for the first-stage sintering, and then raising the temperature to 1180 °C at a heating rate of 5 °C / min and holding for 20 min for the second-stage sintering, other conditions are the same as those in Example 1.

[0116] Example 8

[0117] In this example, except that the content of silicon micropowder is replaced by 280 g and the content of alumina powder is replaced by 220 g, other conditions are the same as those in Example 1. The coating morphology diagram of the porous-coated quartz tube prepared in this example is as shown in Figure 6 shown.

[0118] Example 9

[0119] In this example, except that the content of silica powder is replaced with 240 g and the content of alumina powder is replaced with 260 g, other conditions are the same as those in Example 1.

[0120] Example 10

[0121] In this example, except that the content of silica powder is replaced with 360 g and the content of alumina powder is replaced with 140 g, other conditions are the same as those in Example 1. The coating morphology diagram of the porous coated quartz tube in this example is as Figure 7 shown.

[0122] Example 11

[0123] In this example, except that the content of silica powder is replaced with 400 g and the content of alumina powder is replaced with 100 g, other conditions are the same as those in Example 1. The coating morphology diagram of the porous coated quartz tube in this example is as Figure 8 shown.

[0124] Comparative Example 1

[0125] In this comparative example, except that calcium carbonate is not added in the preparation of the coating, other conditions are the same as those in Example 1.

[0126] The coating morphology diagram of the porous coated quartz tube in this comparative example is as Figure 9 shown.

[0127] Appearance defect analysis, adhesion test and coating thermal shock (i.e., thermal shock test) test were carried out on the porous coated quartz tubes prepared in Examples 1 - 11 and Comparative Example 1, and the test results are shown in Table 3.

[0128] Among them, the coating appearance defects are mainly compared in terms of coating thickness and its uniformity, pore size, etc.;

[0129] The test method for coating adhesion is the cross - cut method. Use a utility knife to cut 6×6 grids. After cutting the lines, gently sweep the surface with a brush to remove loose particles, then stick a tape on the test area, rub it back and forth with your finger to make it stick firmly, and then pull it up. Then classify it according to the following:

[0130] Grade 0: Completely smooth, no delamination in any grid;

[0131] Grade 1: Small pieces of peeling at the intersections, with an affected area of 5%;

[0132] Grade 2: Edge peeling along the intersections, with an affected area of 5% - 15%;

[0133] Grade 3: Whole edge peeling, and part or all of different grids, with an affected area of 15% - 35%;

[0134] Level 4: Peeling along the entire edge, with some grids partially or completely peeled off, affecting an area of 35% - 65%;

[0135] Level 5: Any peeling level that cannot be classified according to 4.

[0136] The test method for the coating under thermal shock is as follows: Heat the porous coating quartz tube to 800 °C, keep it at this temperature for 20 minutes, then take it out and quickly cool it to room temperature. Repeat this operation 5 times, and then test for coating peeling, cracking, and delamination defects.

[0137] Table 3

[0138]

[0139] From the above table, it can be seen that the sample in Example 1 is the most ideal, achieving the purpose of the present invention.

[0140] By comparing Example 1 with Examples 2 - 3, it can be seen that fluctuations in the composition of inorganic micro-materials, differences in the additives for coating preparation, and changes in the spraying thickness will all affect the porous coating structure. Based on the process parameters in Example 1, a coating with achievable performance, appearance, and erosion resistance functions can be prepared;

[0141] By comparing Example 1 with Examples 4 - 5, it can be seen that when the spraying thickness of the coating is too thick, during the gas foaming and expansion process, the force is uneven, forming bubble structures of different sizes. When the spraying thickness is too thin, some areas may not be sprayed properly, resulting in blanks, and the bubbles will directly volatilize into the air without forming bubble structures inside the coating;

[0142] By comparing Example 1 with Examples 6 - 7, it can be seen that replacing sintering with one-stage sintering or two-stage sintering has a great impact on the formation of the porous structure of the coating. Drying → debinding → curing → sintering and foaming are all indispensable.

[0143] By comparing Example 1 with Examples 8 - 11, it can be seen that the mass ratio of silica powder and alumina powder has an obvious impact on the high-temperature properties of the coating. As the framework oxide of the glass, SiO2 can greatly improve the high-temperature viscosity, crystallization performance, chemical stability, etc. of the glass. Alumina, as an intermediate oxide, increases the high-temperature viscosity of the glass and weakens the glass melting property, thereby changing the high-temperature properties of the glass. The processes of bubble generation, diffusion, and encapsulation are all related to the high-temperature properties of the coating. Therefore, a suitable silica-alumina ratio can have a significant impact on the porous structure. Examples show that, on the premise that other processes remain unchanged, when the silica-alumina ratio is around 310:180, the prepared porous coating is the most ideal. With the adjustment of the silica-alumina ratio up and down, the coating structure will change in terms of silica and alumina.

[0144] The mixing ratio of the coatings in Example 8 and Example 10 is within the range of (24~40):(14~26):(5~10):(12~16):(25~35) in terms of the mass ratio of silica powder, alumina powder, talc powder, feldspar powder and cullet in the present invention. The coatings in Example 8 and Example 10 also meet the coating formulation requirements of the invention.

[0145] It can be seen from the comparison between Example 1 and Comparative Example 1 that no foaming agent is added during the coating preparation process, and the coating fails to produce a porous structure.

[0146] The applicant declares that the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A quartz tube, characterized in that, The quartz tube includes a quartz tube and a porous coating provided on the inner wall of the quartz tube; the raw material of the porous coating includes a coating material, and the coating material includes 90-110 parts of inorganic fine powder, 140-160 parts of water, 1-2 parts of thickener, 2.5-4 parts of high-temperature binder, and 1.5-3 parts of foaming agent; The inorganic fine powder includes silica powder, alumina powder, talc powder, feldspar powder, and crushed glass; The mass ratio of the silica powder, alumina powder, talc powder, feldspar powder, and crushed glass is (28-40):(14-26):(5-10):(12-16):(25-35); The foaming agent includes any one or a combination of at least two of calcium carbonate, sodium carbonate, or silicon carbide; The high-temperature binder includes any one or a combination of at least two of silica sol, phosphoric acid solution, or aluminum dihydrogen phosphate; The thickness of the porous coating is 0.4-1.0 mm; The quartz tube is prepared by the following method, and the method includes: spraying the coating material on the inner wall of the quartz tube, and obtaining the quartz tube after drying and sintering; the sintering includes one-stage sintering, two-stage sintering, and three-stage sintering carried out in sequence, the temperature of the one-stage sintering is 100-140 °C, the temperature of the two-stage sintering is 350-400 °C, and the temperature of the three-stage sintering is 1100-1200 °C.

2. The quartz tube according to claim 1, characterized in that, The thickener includes any one or a combination of at least two of polyacrylamide, hydroxypropyl methylcellulose, or carboxymethyl cellulose; 3. The quartz tube according to claim 1, characterized in that, The pore size of the porous coating is 0.3-1.0 mm.

4. A method for preparing a quartz tube according to any one of claims 1-3, characterized in that, The preparation method includes: Dispersing the raw material of the porous coating to obtain a coating material, spraying the coating material on the inner wall of the quartz tube, and obtaining the quartz tube after drying and sintering; the sintering includes one-stage sintering, two-stage sintering, and three-stage sintering carried out in sequence, the temperature of the one-stage sintering is 100-140 °C, the temperature of the two-stage sintering is 350-400 °C, and the temperature of the three-stage sintering is 1100-1200 °C.

5. The preparation method according to claim 4, characterized in that, The preparation method of the coating material includes: preparing the inorganic fine powder into an inorganic fine powder slurry, and then dispersing it with a thickener, a high-temperature binder, and a foaming agent to obtain the coating material.

6. The preparation method according to claim 5, characterized in that, The preparation method of the inorganic fine powder slurry includes: ball-milling the inorganic fine powder, grinding balls, and water to obtain the inorganic fine powder slurry.

7. The preparation method according to claim 6, characterized in that, The mass ratio of the inorganic fine powder, grinding balls, and water is 1:(2-7):(1.2-1.7).

8. The preparation method according to claim 6, wherein The time of the ball-milling is 6-8 h.

9. The preparation method according to claim 4, characterized in that, The thickness of the spraying is 0.4-1 mm.

10. The preparation method according to claim 4, wherein The time of the drying is 2.5-3.5 h.

11. According to the preparation method described in claim 4, characterized in that, The temperature of the drying is 10-35 °C.

12. The preparation method according to claim 4, characterized in that, The heating rate of the one-stage sintering is 5-8 °C / min.

13. The preparation method according to claim 4, characterized in that, The heat preservation time of the one-stage sintering is 25-35 min.

14. The preparation method according to claim 4, characterized in that, The heating rate of the two-stage sintering is 8-10 °C / min.

15. The preparation method according to claim 4, characterized in that, The heat preservation time of the two-stage sintering is 15-25 min.

16. The preparation method according to claim 4, characterized in that, The heating rate of the three-stage sintering is 5-8 °C / min.

17. The preparation method according to claim 4, characterized in that, The heat preservation time of the three-stage sintering is 15-25 min.

18. The preparation method according to claim 4, wherein After the sintering, it is naturally cooled to room temperature to obtain the porous coating quartz tube.

19. The preparation method according to claim 4, characterized in that, The preparation method includes: The raw materials of the porous coating are dispersed to obtain a coating, and the coating is sprayed on the inner wall of the quartz tube with a spraying thickness of 0.4 to 1 mm; The quartz tube is obtained through drying and successive first-stage sintering, second-stage sintering, and third-stage sintering. Among them, the heating rate of the first-stage sintering is 5 to 8 °C / min, the temperature is 100 to 140 °C, and the holding time is 25 to 35 min; the heating rate of the second-stage sintering is 8 to 10 °C / min, the temperature is 350 to 400 °C, and the holding time is 15 to 25 min; the heating rate of the third-stage sintering is 5 to 8 °C / min, the temperature is 1100 to 1200 °C, and the holding time is 15 to 25 min.

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