A composite tin bath top cover brick with heat preservation and insulation function and a preparation method thereof

Abstract

The application discloses a heat-preservation and heat-insulation composite tin bath top cover brick and a preparation method thereof, and belongs to the technical field of heat-insulation brick preparation. The application comprises the following raw material components in parts by weight: 80-100 parts of modified refractory material, 15-20 parts of heat-resistant aerogel, 10-15 parts of composite binder, 5-8 parts of water glass and 8-10 parts of silica sand. In the process of preparing heat-resistant fibers by electrostatic spinning, conductive carbon black is introduced to improve the process efficiency, then the carbon structure is removed by calcination, and hydroxyl groups are introduced to improve the contact area and reaction activity of the heat-resistant fibers and the remaining materials, and the hydroxyl groups are used as the filling structure of the heat-resistant aerogel, the modified refractory material and the composite binder to improve the composite performance of the materials. After mixing and pressing, the lightweight, high-temperature deformation-resistant and compression-resistant heat-preservation and heat-insulation composite top cover brick is obtained.

Description

Technical Field

[0001] This invention relates to the field of heat-insulating brick preparation technology, specifically to a composite tin bath top cover brick for heat insulation and its preparation method. Background Technology

[0002] Lightweight thermal insulation composite tin bath cover bricks are a type of high-performance material commonly used in the metallurgical field. They are mainly used to improve furnace efficiency and control operating temperature. The development of this type of material has gradually transitioned from traditional refractory materials such as clay bricks to lightweight composite materials, such as those combining refractory ceramic fibers and high-performance ceramics. Modern composite materials improve mechanical strength and chemical resistance by adding components such as carbon fibers, while also optimizing thermal insulation performance. Nevertheless, existing technologies still have drawbacks such as temperature resistance limitations, high costs, joint surface issues, and environmental challenges. Future research and development will focus on solving these problems and seeking innovative solutions to promote the widespread application of this material, especially in areas where lightweight and thermal insulation are pursued while improving mechanical properties.

[0003] The prior art CN106278202A discloses a lightweight refractory brick and its preparation method, comprising the following raw materials in the following mass percentages: 20-55% alumina hollow spheres, 20-40% cenospheres, 6-10% binder, 1-3% alumina micro powder, 5-20% soft clay, and 10-30% mullite micro powder. The brick blank prepared using the above-mentioned raw materials in the above mass percentages and then dried and sintered has high refractory performance and good thermal stability, as well as long service life and low heat loss.

[0004] However, the aforementioned patent describes the introduction of hollow alumina spheres into the refractory brick structure to reduce the bulk density and refractory performance of the material. However, the hollow alumina sphere structure is relatively fragile and has low mechanical strength. The alumina microspheres lack support during the filling process and are prone to breakage during processing and use, which affects the stability of the structure. As a result, the lightweight performance and thermal insulation performance of the material need to be further improved.

[0005] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a thermally insulating composite tin bath top cover brick and its preparation method, which solves the technical problem that the lightweight performance and thermal insulation performance of existing composite top cover bricks need to be further improved.

[0007] The objective of this invention can be achieved through the following technical solution: a thermal insulation composite tin bath top cover brick, comprising the following raw material components by weight: 80-100 parts modified refractory, 15-20 parts heat-resistant aerogel, 10-15 parts composite binder, 5-8 parts water glass and 8-10 parts silica sand.

[0008] The preparation method of modified refractory materials includes the following steps:

[0009] A1. Add ultrafine calcined kaolin, heat-resistant fiber, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, deionized water and sodium hydroxide powder to a reaction vessel and stir. Raise the temperature of the reaction vessel to 60-80℃, keep it at the temperature and stir for 20-40 minutes, and then process to obtain refractory material.

[0010] The reaction principle for preparing refractory materials is as follows: under alkaline conditions and with the promotion of heating, the silane-hydrogen bonds on 3-(2,3-epoxypropoxy)propyltrimethoxysilane undergo hydrolysis to form a silanol structure, and the epoxy group undergoes ring opening to generate free radicals, which act as a bridge to enable ultrafine calcined kaolin and heat-resistant fibers to form a cross-linked structure, thus obtaining refractory materials.

[0011] A2. After pressing the refractory material into shape, it is transferred to a muffle furnace and calcined to obtain modified refractory material.

[0012] Further, in step A1, the stirring speed of the reactor is 80-120 rpm, and the ratio of ultrafine calcined kaolin, heat-resistant fiber, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, deionized water, and sodium hydroxide powder is 8-10 g: 1-2 g: 0.5-0.8 g: 20-30 mL. The post-treatment includes: after the reaction is completed, after the reactor temperature drops to room temperature, the reaction liquid is filtered to collect the filter cake, and the filter cake is washed 3-5 times with anhydrous ethanol and deionized water. The filter cake is then transferred to a drying oven at 60-80℃ and vacuum dried until the filter cake reaches a constant weight to obtain the refractory material. In step A2, the calcination operation is as follows: after nitrogen protection is introduced into the muffle furnace, the muffle furnace is heated to 1350-1600℃ at a heating rate of 5-8℃ / min, and the reaction is held at this temperature for 4-6 hours. The mixture is then naturally cooled to room temperature to obtain the modified refractory material.

[0013] Furthermore, the method for preparing heat-resistant aerogel includes the following steps:

[0014] B1. Add modified hollow spheres, heat-resistant fibers and deionized water to a reaction vessel. Stir at room temperature for 10-15 minutes. After the temperature of the reaction vessel is raised to 80-90℃, stop stirring. Adjust the pH of the system to 8-10 using saturated sodium hydroxide solution. Keep the reaction at this temperature for 2-3 hours to obtain a composite gel.

[0015] The reaction principle for preparing the composite gel is as follows: under alkaline conditions and high temperature catalysis, the siloxane structure on the surface of the modified hollow sphere undergoes hydrolysis, generating self-crosslinking and crosslinking with hydroxyl groups on the surface of the heat-resistant fiber and inside the void structure, ultimately preparing the composite gel.

[0016] B2. After transferring the composite gel into a stainless steel mold, the stainless steel mold is transferred to a copper column immersed in liquid nitrogen and left to stand for 20-30 minutes. The heat-resistant aerogel is then obtained through post-processing.

[0017] The reaction principle for preparing heat-resistant aerogel is as follows: after the composite gel is frozen by an ultra-low temperature copper column, the solvent inside the composite gel takes the form of an ice crystal structure. After vacuum sublimation, an aerogel structure is obtained, and finally, a heat-resistant aerogel is prepared.

[0018] Further, in step B1, the stirring rate of the reactor is 80-120 rpm, and the ratio of modified hollow spheres, heat-resistant fibers and deionized water is 3-5 g: 2-3 g: 20-30 mL; in step B2, the post-treatment includes: after standing, transferring the mold to a vacuum dryer, setting the temperature to 40-60℃, the vacuum degree to 5-8 mBar, and vacuum drying for 1-2 hours to obtain heat-resistant aerogel.

[0019] Furthermore, the preparation method of the modified hollow spheres includes the following steps:

[0020] C1. Add hollow glass microspheres and 2-4wt% sodium hydroxide aqueous solution to a reaction vessel and stir. Raise the temperature of the reaction vessel to 60-80℃ and keep it at this temperature for 1-2 hours. After post-treatment, etched microspheres are obtained.

[0021] The reaction principle for preparing etched microspheres is as follows: under alkaline and heating conditions, the surface of hollow glass microspheres is etched, resulting in an etching effect and introducing the active functional group hydroxyl structure, ultimately preparing etched microspheres.

[0022] C2. Add the etched microspheres, triethylamine, and N,N-dimethylformamide to the reaction vessel, purge with nitrogen for protection, add the modification solution to the reaction vessel, react for 40-60 min, and then perform post-treatment to obtain modified hollow spheres.

[0023] The reaction principle for preparing modified hollow spheres is as follows: under the promotion of a catalyst and the protection of a nitrogen atmosphere, the isocyanate groups on 3-isocyanate-propyltrimethoxysilane in the modification solution react with the hydroxyl groups on the surface of the etched microspheres, ultimately introducing a siloxane structure onto the surface of the etched microspheres, and finally preparing the modified hollow spheres.

[0024] Further, in step C1, the ratio of hollow glass microspheres to 2-4 wt% sodium hydroxide aqueous solution is 1-2 g: 10-15 mL, the stirring speed of the reactor is 80-120 rpm, and the post-treatment includes: after the reaction is completed, after the temperature of the reactor drops to room temperature, the reaction solution is filtered to collect the filter cake, the filter cake is washed 3-5 times with anhydrous ethanol and deionized water, and the filter cake is transferred to a drying oven at a temperature of 60-80℃ and vacuum dried until the filter cake reaches constant weight to obtain etched microspheres.

[0025] Further, in step C2, the ratio of etching microspheres, triethylamine, N,N-dimethylformamide, and modification solution is 4-5g:0.5-0.8g:15-18mL:8-10mL. The modification solution is obtained by mixing 3-isocyanate-propyltrimethoxysilane and N,N-dimethylformamide at a ratio of 1-2g:5mL. The post-treatment includes: after the reaction is completed, after the temperature of the reaction vessel drops to room temperature, the reaction solution is filtered to collect the filter cake. The filter cake is washed 3-5 times with anhydrous ethanol and deionized water. The filter cake is then transferred to a drying oven at a temperature of 60-80℃ and vacuum dried until the filter cake reaches a constant weight to obtain modified hollow spheres.

[0026] Furthermore, the method for preparing heat-resistant fibers includes the following steps:

[0027] D1. Add aluminum chloride hexahydrate, methyl orthosilicate and deionized water to the reaction vessel, stir at room temperature for 10-15 minutes, then add auxiliary agent and conductive carbon black to the reaction vessel to obtain spinning solution;

[0028] D2. Add the spinning solution to the electrospinning machine and obtain the heat-resistant fiber precursor by electrospinning.

[0029] D3. The heat-resistant fiber precursor is transferred to a tube furnace and calcined to obtain heat-resistant fiber.

[0030] The reaction principle for preparing heat-resistant fibers is as follows: with the aid of supplementation and catalysis, the spinning solution has an aluminum-silicon hydrolysis mixed structure. After the addition of conductive carbon black, the electrospinning process is promoted. After spinning is completed, calcination is performed to remove the carbon structure and make the fiber form a stable aluminum-silicon structure. After modification with water vapor, hydroxyl structures are formed in the voids and surface of the fiber, and finally a heat-resistant fiber with high porosity and high activity is prepared.

[0031] Further, in step D1, the ratio of aluminum chloride hexahydrate, methyl orthosilicate, deionized water, auxiliary agent, and conductive carbon black is 12-15g:6-8g:40-50mL:12-16g:3-5g. The auxiliary agent is a mixture of aluminum isopropoxide, acetic acid, and polyvinylpyrrolidone in a ratio of 12-16g:2-3g:1-2g. In step D2, the electrospinning voltage is 20-24kV, the receiving distance is 20-25cm, the infusion rate is 6-8mL / h, the sliding table moving speed is 25-30cm / min, and the receiving roller rotation speed is 25-30r / min.

[0032] Furthermore, in step D3, the calcination operation includes the following steps: After nitrogen protection is introduced into the tubular furnace, the furnace is heated to 600-650℃ at a heating rate of 5-6℃ / min. The nitrogen is then turned off, and oxygen is introduced at a flow rate of 1-2L / min. After holding at this temperature for 1-2 hours, the oxygen is turned off, and nitrogen is introduced again. The furnace is then heated to 1250-1350℃ at a heating rate of 5-6℃ / min. After holding at this temperature for 1-2 hours, the furnace is allowed to cool naturally to 100-120℃. The nitrogen is then turned off, and water vapor is introduced at a flow rate of 1-3L / min. After holding at this temperature for 1-2 hours, heat-resistant fibers are obtained.

[0033] Furthermore, the preparation method of the composite adhesive is as follows: Bisphenol A type epoxy resin, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, triethylamine and acetone are added to a reaction vessel and stirred. The temperature of the reaction vessel is raised to 60-80℃ and stirred for 20-40 min. Then, heat-resistant fiber and hydroxyl polysiloxane are added to the reaction vessel and stirred for 10-15 min. Then, saturated sodium hydroxide solution is added to the reaction vessel to adjust the pH of the system to 8-10. The reaction is carried out for 1-2 h and then post-treated to obtain the composite adhesive.

[0034] The reaction principle for preparing the composite adhesive is as follows: after modification with 3-(2,3-epoxypropoxy)propyltrimethoxysilane, a siloxane structure is introduced into the structure of bisphenol A epoxy resin. Then, through hydrolysis, the bisphenol A epoxy resin is combined with heat-resistant fibers and hydroxyl polysiloxane to finally prepare the composite adhesive.

[0035] Furthermore, the stirring speed of the reactor is 80-120 rpm, and the ratio of bisphenol A epoxy resin, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, triethylamine, acetone, heat-resistant fiber and hydroxyl polysiloxane is 8-10g:2-3g:0.3-0.5g:30-40mL:2-3g:5-6g. The post-treatment includes: after the reaction is completed, wait for the reactor temperature to drop to room temperature, add the reaction solution to a rotary evaporator with a water bath temperature of 80-100℃, and distill under reduced pressure until no liquid is collected to obtain the composite adhesive.

[0036] This invention also proposes a method for preparing a composite tin bath top cover brick with thermal insulation properties, comprising the following steps:

[0037] S1. Add the modified refractory, heat-resistant aerogel and silica sand to a pulverizer, pulverize and pass through a 400-600 mesh sieve to obtain a mixture;

[0038] S2. After adding the mixture into the homogenizer, add the composite binder into the homogenizer, homogenize and mix for 8-10 minutes, then add water glass and continue homogenizing and mixing for 5-6 minutes. Discharge and press into bricks.

[0039] S3. Transfer the bricks to a drying kiln at 250-270℃ for drying for 24-36 hours. After cooling, the composite top cover bricks are obtained.

[0040] The present invention has the following beneficial effects:

[0041] This invention introduces conductive carbon black into the electrospinning process for preparing heat-resistant fibers, significantly improving the overall conductivity of the spinning solution. During electrospinning, this facilitates the formation of jetted fibers under high voltage, resulting in a structurally stable heat-resistant fiber precursor. During calcination, the carbon black is pyrolyzed at controlled temperatures to form a stable porous structure. High-temperature steam modification then forms active hydroxyl structures with functional groups on its surface. This allows for the formation of a tight cross-linked support structure with the abundant porous structure and surface-active hydroxyl groups during the preparation of heat-resistant aerogels, modified refractory materials, and composite binders. This significantly enhances the structural stability of the materials. Finally, through mixing and pressing, a lightweight, high-temperature resistant, and pressure-resistant composite roofing brick with thermal insulation properties is obtained.

[0042] In the preparation of heat-resistant aerogel, this invention utilizes the hydrolysis of silica-oxygen groups on the surface of modified hollow spheres and the hydrolysis of heat-resistant fibers modified with high-porosity active functional groups to obtain a structurally stable heat-resistant aerogel. The microstructure of the heat-resistant aerogel consists of a very fine and continuous network-like solid framework. These microstructures significantly reduce the actual volume of the material while maintaining its integrity. Working synergistically with the hollow structure of the modified hollow spheres, this reduces the bulk density of the composite top cover brick. Furthermore, the air layer inside the heat-resistant aerogel and the modified glass spheres significantly reduces heat transfer through the material, thereby significantly lowering the thermal conductivity of the composite top cover brick. During vacuum drying, the fiber structure provides a larger surface area, which helps accelerate the contact between ice crystals and air, making the sublimation process faster and more uniform. During use, the fiber structure provides support for the glass hollow structure, thus ensuring the stability of the material structure.

[0043] In the preparation of the composite binder, this invention utilizes a composite binder with heat-resistant fibers as the supporting structure, which is a mixture of bisphenol A type epoxy resin and hydroxyl polysiloxane. Compared to directly using bisphenol A type epoxy resin, the composite binder's internal structure, supported by heat-resistant fibers and modified by hydroxyl polysiloxane, reduces the material's coefficient of thermal expansion and improves its dimensional stability under temperature changes. This reduces the permanent linear change of the composite top cover brick during heating. The heat-resistant fibers enhance the overall mechanical properties of the bisphenol A type epoxy resin, thereby improving the structural stability of the composite binder and helping to maintain the material's structural integrity, thus increasing the material's room temperature compressive strength. In the preparation of the refractory material, a silane coupling agent is used to crosslink the heat-resistant fibers and ultrafine calcined kaolin, providing structural support to the ultrafine calcined kaolin during calcination, ultimately resulting in a structurally stable modified refractory material. Detailed Implementation

[0044] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] The ultrafine calcined kaolin used in this invention was purchased from Shandong Qiyi Chemical Technology Co., Ltd.

[0046] The bisphenol A type epoxy resin used in this invention was purchased from Guodu Chemical (Kunshan) Co., Ltd., and its brand name is YD-128.

[0047] The hydroxyl polysiloxane used in this invention was purchased from Jiangsu Kexing New Materials Co., Ltd., with product number F-20. Example 1

[0048] This embodiment provides a method for preparing modified hollow spheres for the preparation of heat-resistant aerogel in composite tin bath top cover bricks with thermal insulation properties, including the following steps:

[0049] Step 1: Preparation of etched microspheres

[0050] Weigh 100.0g of hollow glass microspheres and 1.0L of 2.0wt% sodium hydroxide aqueous solution and add them to the reaction vessel. Stir at 80rpm and raise the temperature of the reaction vessel to 60℃. Keep the reaction vessel at this temperature for 1h. After the reaction is complete, wait for the temperature of the reaction vessel to drop to room temperature, filter the reaction solution and collect the filter cake. Wash the filter cake three times with anhydrous ethanol and deionized water. Transfer the filter cake to a drying oven at 60℃ and vacuum dry it until the filter cake reaches a constant weight to obtain etched microspheres.

[0051] Step 2: Preparation of modified hollow spheres

[0052] Weigh out 100.0 g of 3-isocyanate-propyltrimethoxysilane and mix with 500.0 mL of N,N-dimethylformamide to obtain the modified solution;

[0053] Weigh out 400.0 g of etched microspheres, 50.0 g of triethylamine and 1.5 L of N,N-dimethylformamide and add them to the reaction vessel. Purge with nitrogen for protection. Add 800.0 mL of modification solution to the reaction vessel and react for 40 min. After the reaction is complete, wait for the temperature of the reaction vessel to drop to room temperature, filter the reaction solution and collect the filter cake. Wash the filter cake three times with anhydrous ethanol and deionized water. Transfer the filter cake to a drying oven at 60 °C and vacuum dry it until the filter cake reaches constant weight to obtain modified hollow spheres. Example 2

[0054] This embodiment provides a method for preparing modified hollow spheres for the preparation of heat-resistant aerogel in composite tin bath top cover bricks with thermal insulation properties, including the following steps:

[0055] Step 1: Preparation of etched microspheres

[0056] Weigh 200.0g of hollow glass microspheres and 1.5L of 4.0wt% sodium hydroxide aqueous solution and add them to the reaction vessel. Stir at 120rpm and raise the temperature of the reaction vessel to 80℃. Keep the reaction vessel at this temperature for 2h. After the reaction is complete, wait for the temperature of the reaction vessel to drop to room temperature, filter the reaction solution and collect the filter cake. Wash the filter cake 5 times with anhydrous ethanol and deionized water. Transfer the filter cake to a drying oven at 80℃ and vacuum dry it until the filter cake reaches a constant weight to obtain etched microspheres.

[0057] Step 2: Preparation of modified hollow spheres

[0058] Weigh out 150.0 g of 3-isocyanate-propyltrimethoxysilane and mix with 500.0 mL of N,N-dimethylformamide to obtain the modified solution;

[0059] Weigh out 450.0 g of etched microspheres, 65.0 g of triethylamine and 1.6 L of N,N-dimethylformamide and add them to the reaction vessel. Purge with nitrogen for protection. Add 1.0 L of modification solution to the reaction vessel and react for 60 min. After the reaction is complete, wait for the temperature of the reaction vessel to drop to room temperature, filter the reaction solution and collect the filter cake. Wash the filter cake 5 times with anhydrous ethanol and deionized water. Transfer the filter cake to a drying oven at 60 °C and vacuum dry it until the filter cake reaches constant weight to obtain modified hollow spheres. Example 3

[0060] This embodiment provides a method for preparing modified hollow spheres for the preparation of heat-resistant aerogel in composite tin bath top cover bricks with thermal insulation properties, including the following steps:

[0061] Step 1: Preparation of etched microspheres

[0062] Weigh 150.0g of hollow glass microspheres and 1.2L of 3.0wt% sodium hydroxide aqueous solution and add them to the reaction vessel. Stir at 100rpm and raise the temperature of the reaction vessel to 70℃. Keep the reaction vessel at this temperature for 2h. After the reaction is complete, wait for the temperature of the reaction vessel to drop to room temperature, filter the reaction solution and collect the filter cake. Wash the filter cake four times with anhydrous ethanol and deionized water. Transfer the filter cake to a drying oven at 70℃ and vacuum dry it until the filter cake reaches a constant weight to obtain etched microspheres.

[0063] Step 2: Preparation of modified hollow spheres

[0064] Weigh out 150.0 g of 3-isocyanate-propyltrimethoxysilane and mix with 500.0 mL of N,N-dimethylformamide to obtain the modified solution;

[0065] Weigh out 450.0 g of etched microspheres, 70.0 g of triethylamine and 1.6 L of N,N-dimethylformamide and add them to the reaction vessel. Purge with nitrogen for protection. Add 900.0 mL of modification solution to the reaction vessel and react for 50 min. After the reaction is complete, wait for the temperature of the reaction vessel to drop to room temperature, filter the reaction solution and collect the filter cake. Wash the filter cake four times with anhydrous ethanol and deionized water. Transfer the filter cake to a drying oven at 70 °C and vacuum dry it until the filter cake reaches constant weight to obtain modified hollow spheres. Example 4

[0066] This embodiment provides a method for preparing heat-resistant fibers for heat-resistant aerogel used in the preparation of thermally insulating composite tin bath top cover bricks, including the following steps:

[0067] Step ①: Prepare spinning solution

[0068] Weigh out 1.2 kg of aluminum isopropoxide, 200.0 g of acetic acid and 100.0 g of polyvinylpyrrolidone and mix them to obtain the auxiliary agent;

[0069] Weigh out 1.2 kg of aluminum chloride hexahydrate, 600.0 g of methyl orthosilicate and 4.0 L of deionized water and add them to the reaction vessel. Stir at room temperature for 10 min, then add 1.2 kg of auxiliary agent and 300.0 g of conductive carbon black to the reaction vessel to obtain the spinning solution.

[0070] Step 2: Preparation of heat-resistant fiber precursor

[0071] The spinning solution was added to an electrospinning machine. The electrospinning voltage was 20kV, the receiving distance was 20cm, the infusion rate was 6.0mL / h, the slide table moving speed was 25cm / min, and the receiving roller rotation speed was 25r / min, to obtain a heat-resistant fiber precursor.

[0072] Step 3: Preparation of heat-resistant fibers

[0073] The heat-resistant fiber precursor was transferred to a tube furnace. After nitrogen protection was introduced into the tube furnace, the temperature was increased to 600°C at a heating rate of 5°C / min. The nitrogen was then turned off, and oxygen was introduced at a flow rate of 1.0 L / min. After holding at this temperature for 1 hour, the oxygen was turned off, and nitrogen was introduced again. The temperature was increased to 1250°C at a heating rate of 5°C / min. After holding at this temperature for 1 hour, the temperature was allowed to cool naturally to 100°C. The nitrogen was then turned off, and water vapor was introduced at a flow rate of 1.0 L / min. After holding at this temperature for 1 hour, heat-resistant fiber was obtained. Example 5

[0074] This embodiment provides a method for preparing heat-resistant fibers for heat-resistant aerogel used in the preparation of thermally insulating composite tin bath top cover bricks, including the following steps:

[0075] Step ①: Prepare spinning solution

[0076] Weigh out 1.6 kg of aluminum isopropoxide, 300.0 g of acetic acid and 200.0 g of polyvinylpyrrolidone and mix them to obtain the auxiliary agent;

[0077] Weigh out 1.5 kg of aluminum chloride hexahydrate, 800.0 g of methyl orthosilicate and 5.0 L of deionized water and add them to the reaction vessel. Stir at room temperature for 15 min, then add 1.6 kg of auxiliary agent and 500.0 g of conductive carbon black to the reaction vessel to obtain the spinning solution.

[0078] Step 2: Preparation of heat-resistant fiber precursor

[0079] The spinning solution was added to an electrospinning machine. The electrospinning voltage was 24kV, the receiving distance was 25cm, the infusion rate was 8mL / h, the slide table moving speed was 30cm / min, and the receiving roller rotation speed was 30r / min, to obtain a heat-resistant fiber precursor.

[0080] Step 3: Preparation of heat-resistant fibers

[0081] The heat-resistant fiber precursor was transferred to a tube furnace. After nitrogen protection was introduced into the tube furnace, the temperature was increased to 650°C at a heating rate of 6°C / min. The nitrogen was then turned off, and oxygen was introduced at a flow rate of 2.0 L / min. After holding at this temperature for 2 hours, the oxygen was turned off, and nitrogen was introduced again. The temperature was increased to 1350°C at a heating rate of 6°C / min. After holding at this temperature for 2 hours, the temperature was allowed to cool naturally to 120°C. The nitrogen was then turned off, and water vapor was introduced at a flow rate of 3.0 L / min. After holding at this temperature for 2 hours, the heat-resistant fiber was obtained. Example 6

[0082] This embodiment provides a method for preparing heat-resistant fibers for heat-resistant aerogel used in the preparation of thermally insulating composite tin bath top cover bricks, including the following steps:

[0083] Step ①: Prepare spinning solution

[0084] Weigh out 1.5 kg of aluminum isopropoxide, 250.0 g of acetic acid and 150.0 g of polyvinylpyrrolidone and mix them to obtain the auxiliary agent;

[0085] Weigh out 1.3 kg of aluminum chloride hexahydrate, 700.0 g of methyl orthosilicate and 4.5 L of deionized water and add them to the reaction vessel. Stir at room temperature for 12 min, then add 1.5 kg of auxiliary agent and 400.0 g of conductive carbon black to the reaction vessel to obtain the spinning solution.

[0086] Step 2: Preparation of heat-resistant fiber precursor

[0087] The spinning solution was added to an electrospinning machine. The electrospinning voltage was 21kV, the receiving distance was 24cm, the infusion rate was 7mL / h, the slide table moving speed was 27cm / min, and the receiving roller rotation speed was 27r / min, thus obtaining a heat-resistant fiber precursor.

[0088] Step 3: Preparation of heat-resistant fibers

[0089] The heat-resistant fiber precursor was transferred to a tube furnace. After nitrogen protection was introduced into the tube furnace, the temperature was increased to 640°C at a heating rate of 6°C / min. The nitrogen was then turned off, and oxygen was introduced at a flow rate of 1.5 L / min. After holding at this temperature for 2 hours, the oxygen was turned off, and nitrogen was introduced again. The temperature was increased to 1300°C at a heating rate of 6°C / min. After holding at this temperature for 2 hours, the temperature was allowed to cool naturally to 110°C. The nitrogen was then turned off, and water vapor was introduced at a flow rate of 2.0 L / min. After holding at this temperature for 2 hours, the heat-resistant fiber was obtained. Example 7

[0090] This embodiment provides a method for preparing heat-resistant aerogel for composite tin bath top cover bricks with thermal insulation properties, including the following steps:

[0091] Step I: Preparation of composite gel

[0092] Weigh out 300.0g of the modified hollow spheres prepared in Example 1, 200.0g of the heat-resistant fiber prepared in Example 4, and 2.0L of deionized water and add them to the reaction vessel. Stir at 80rpm for 10min at room temperature, then raise the temperature of the reaction vessel to 800℃ and stop stirring. Adjust the pH of the system to 8 using saturated sodium hydroxide solution and keep the reaction at this temperature for 2h to obtain the composite gel.

[0093] Step II: Preparation of heat-resistant aerogel

[0094] After transferring the composite gel into a stainless steel mold, the stainless steel mold was transferred to a copper column immersed in liquid nitrogen and allowed to stand for 20 minutes. After standing, the mold was transferred to a vacuum dryer, and the temperature was set to 40℃ and the vacuum degree to 5mBar. Vacuum drying was carried out for 1 hour to obtain a heat-resistant aerogel. Example 8

[0095] This embodiment provides a method for preparing heat-resistant aerogel for composite tin bath top cover bricks with thermal insulation properties, including the following steps:

[0096] Step I: Preparation of composite gel

[0097] Weigh out 500.0g of the modified hollow spheres prepared in Example 2, 300.0g of the heat-resistant fiber prepared in Example 5, and 3.0L of deionized water and add them to the reaction vessel. Stir at 120rpm for 15min at room temperature. After the temperature of the reaction vessel is raised to 90℃, stop stirring. Adjust the pH of the system to 10 using saturated sodium hydroxide solution and keep the reaction at this temperature for 3h to obtain the composite gel.

[0098] Step II: Preparation of heat-resistant aerogel

[0099] After transferring the composite gel into a stainless steel mold, the stainless steel mold was transferred to a copper column immersed in liquid nitrogen and allowed to stand for 30 minutes. After standing, the mold was transferred to a vacuum dryer, and the temperature was set to 60℃ and the vacuum degree to 8mBar. Vacuum drying was carried out for 2 hours to obtain a heat-resistant aerogel. Example 9

[0100] This embodiment provides a method for preparing heat-resistant aerogel for composite tin bath top cover bricks with thermal insulation properties, including the following steps:

[0101] Step I: Preparation of composite gel

[0102] Weigh out 400.0g of the modified hollow spheres prepared in Example 3, 250.0g of the heat-resistant fiber prepared in Example 6, and 2.5L of deionized water and add them to the reaction vessel. Stir at 100rpm for 12min at room temperature. After the temperature of the reaction vessel is raised to 85℃, stop stirring. Adjust the pH of the system to 9 using saturated sodium hydroxide solution and keep the reaction at this temperature for 3h to obtain the composite gel.

[0103] Step II: Preparation of heat-resistant aerogel

[0104] After transferring the composite gel into a stainless steel mold, the stainless steel mold was transferred to a copper column immersed in liquid nitrogen and allowed to stand for 25 minutes. After standing, the mold was transferred to a vacuum dryer, and the temperature was set to 50°C and the vacuum degree to 6 mBar. Vacuum drying was carried out for 1.5 hours to obtain a heat-resistant aerogel. Example 10

[0105] This embodiment provides a method for preparing a thermally insulating composite tin bath top cover brick, including the following steps:

[0106] Step 1: Preparation of modified refractory materials

[0107] Weigh out 800.0g of ultrafine calcined kaolin, 100.0g of heat-resistant fiber prepared in Example 4, 50.0g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 2.0L of deionized water and 50.0g of sodium hydroxide powder and add them to the reaction vessel. Stir at 80 rpm and raise the temperature of the reaction vessel to 60°C. Keep the temperature and stir for 20 min. After the reaction is completed, wait for the temperature of the reaction vessel to drop to room temperature, filter the reaction liquid and collect the filter cake. Wash the filter cake three times with anhydrous ethanol and deionized water. Transfer the filter cake to a drying oven at 60°C and vacuum dry it until the filter cake reaches constant weight to obtain refractory material.

[0108] After the refractory material is pressed into shape, it is transferred to a muffle furnace. The muffle furnace is then purged with nitrogen for protection and heated to 1350°C at a rate of 5°C / min. The reaction is held at this temperature for 4 hours and then allowed to cool naturally to room temperature to obtain the modified refractory material.

[0109] Step 2: Preparation of composite adhesive

[0110] Weigh out 800.0g of bisphenol A epoxy resin, 200.0g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 30.0g of triethylamine, and 3.0L of acetone and add them to a reaction vessel. Stir at 80rpm and raise the temperature of the reaction vessel to 60℃. After stirring for 20min, add 200.0g of the heat-resistant fiber prepared in Example 4 and 500.0g of hydroxyl polysiloxane to the reaction vessel. After stirring for 10min, add saturated sodium hydroxide solution to the reaction vessel to adjust the pH of the system to 8. Keep the reaction vessel at this temperature for 1h. After the reaction is complete, wait for the temperature of the reaction vessel to drop to room temperature, and then add the reaction solution to a rotary evaporator with a water bath temperature of 80℃. Distill under reduced pressure until no liquid is collected to obtain the composite adhesive.

[0111] Step 3: Preparation of composite top cover bricks

[0112] Weigh out 8.0 kg of modified refractory material, 1.5 kg of heat-resistant aerogel prepared in Example 7, and 800.0 g of silica sand, add them to a pulverizer, pulverize them, and pass them through a 400-mesh sieve to obtain a mixture;

[0113] After adding the mixture to the homogenizer, add 1.0 kg of composite binder to the homogenizer and homogenize for 8 minutes. Then add 500.0 g of water glass and continue homogenizing for 5 minutes. The material is then discharged and pressed into bricks.

[0114] The bricks were transferred to a drying kiln at 250°C for 24 hours to dry. After cooling, composite top cover bricks were obtained. Example 11

[0115] This embodiment provides a method for preparing a thermally insulating composite tin bath top cover brick, including the following steps:

[0116] Step 1: Preparation of modified refractory materials

[0117] Weigh out 1.0 kg of ultrafine calcined kaolin, 200.0 g of heat-resistant fiber prepared in Example 5, 80.0 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3.0 L of deionized water and 80.0 g of sodium hydroxide powder and add them to the reaction vessel. Stir at 120 rpm and raise the temperature of the reaction vessel to 80 °C. Keep stirring for 40 min. After the reaction is completed, wait for the temperature of the reaction vessel to drop to room temperature, filter the reaction liquid and collect the filter cake. Wash the filter cake 5 times with anhydrous ethanol and deionized water. Transfer the filter cake to a drying oven at 80 °C and vacuum dry it until the filter cake reaches constant weight to obtain refractory material.

[0118] After the refractory material is pressed into shape, it is transferred to a muffle furnace. The muffle furnace is then purged with nitrogen for protection and heated to 1600°C at a rate of 8°C / min. The reaction is held at this temperature for 6 hours and then allowed to cool naturally to room temperature to obtain the modified refractory material.

[0119] Step 2: Preparation of composite adhesive

[0120] Weigh out 1.0 kg of bisphenol A type epoxy resin, 300.0 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 50.0 g of triethylamine, and 4.0 L of acetone and add them to a reaction vessel. Stir at 120 rpm and raise the temperature of the reaction vessel to 80°C. After stirring for 40 min, add 300.0 g of the heat-resistant fiber prepared in Example 5 and 600.0 g of hydroxyl polysiloxane to the reaction vessel. After stirring for 15 min, add saturated sodium hydroxide solution to the reaction vessel to adjust the pH of the system to 10. Keep the reaction vessel at this temperature for 2 h. After the reaction is complete, wait for the temperature of the reaction vessel to drop to room temperature, and then add the reaction solution to a rotary evaporator with a water bath temperature of 100°C. Distill under reduced pressure until no liquid is collected to obtain the composite adhesive.

[0121] Step 3: Preparation of composite top cover bricks

[0122] Weigh out 10.0 kg of modified refractory, 2.0 kg of heat-resistant aerogel prepared in Example 8, and 1.0 kg of silica sand. Add them to a pulverizer, pulverize them, and pass them through a 400-mesh sieve to obtain a mixture.

[0123] After adding the mixture to the homogenizer, add 1.5 kg of composite binder to the homogenizer and homogenize for 10 minutes. Then add 800.0 g of water glass and continue homogenizing for 6 minutes. The material is then discharged and pressed into bricks.

[0124] The bricks were transferred to a drying kiln at 270℃ for 36 hours to dry. After cooling, composite top cover bricks were obtained. Example 12

[0125] This embodiment provides a method for preparing a thermally insulating composite tin bath top cover brick, including the following steps:

[0126] Step 1: Preparation of modified refractory materials

[0127] Weigh out 900.0g of ultrafine calcined kaolin, 150.0g of heat-resistant fiber prepared in Example 6, 65.0g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 2.5L of deionized water and 65.0g of sodium hydroxide powder and add them to the reaction vessel. Stir at 100rpm and raise the temperature of the reaction vessel to 70℃. Keep the temperature and stir for 30min. After the reaction is completed, wait for the temperature of the reaction vessel to drop to room temperature, filter the reaction liquid and collect the filter cake. Wash the filter cake 4 times with anhydrous ethanol and deionized water. Transfer the filter cake to a drying oven at 70℃ and vacuum dry it until the filter cake reaches constant weight to obtain refractory material.

[0128] After the refractory material is pressed into shape, it is transferred to a muffle furnace. The muffle furnace is then purged with nitrogen for protection and heated to 1560°C at a rate of 6°C / min. The reaction is held at this temperature for 5 hours and then allowed to cool naturally to room temperature to obtain the modified refractory material.

[0129] Step 2: Preparation of composite adhesive

[0130] Weigh out 900.0g of bisphenol A epoxy resin, 250.0g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 40.0g of triethylamine, and 3.5L of acetone and add them to a reaction vessel. Stir at 100rpm and raise the temperature of the reaction vessel to 70℃. After stirring for 30min, add 250.0g of the heat-resistant fiber prepared in Example 6 and 540.0g of hydroxyl polysiloxane to the reaction vessel. After stirring for 12min, add saturated sodium hydroxide solution to the reaction vessel to adjust the pH of the system to 9. Keep the reaction vessel at this temperature for 2h. After the reaction is complete, wait for the temperature of the reaction vessel to drop to room temperature, and then add the reaction solution to a rotary evaporator with a water bath temperature of 90℃. Distill under reduced pressure until no liquid is collected to obtain the composite adhesive.

[0131] Step 3: Preparation of composite top cover bricks

[0132] Weigh out 9.0 kg of modified refractory material, 1.8 kg of heat-resistant aerogel prepared in Example 9, and 900.0 g of silica sand. Add them to a pulverizer, pulverize them, and pass them through a 500-mesh sieve to obtain a mixture.

[0133] After adding the mixture to the homogenizer, add 1.2 kg of composite binder to the homogenizer and homogenize for 9 minutes. Then add 650.0 g of water glass and continue homogenizing for 6 minutes. The material is then discharged and pressed into bricks.

[0134] The bricks were transferred to a drying kiln at 260℃ for 30 hours to dry. After cooling, composite top cover bricks were obtained.

[0135] Comparative Example 1

[0136] The difference between this comparative example and Example 12 is that the addition of conductive carbon black was omitted in step ① during the preparation of the heat-resistant fiber.

[0137] Comparative Example 2

[0138] The difference between this comparative example and Example 12 is that the heat-resistant aerogel is omitted in step three.

[0139] Comparative Example 3

[0140] The difference between this comparative example and Example 12 is that the step of preparing the composite adhesive is omitted in step three, and bisphenol A type epoxy resin is used to replace the composite adhesive in an equal amount.

[0141] Performance testing:

[0142] The bulk density, permanent linear change upon heating, compressive strength at room temperature, and thermal conductivity of the composite top cover bricks prepared in Examples 10-12 and Comparative Examples 1-3 were tested according to standard YB / T 4857-2020 "Semi-siliceous Insulating Refractory Bricks". Specific data are shown in Table 1.

[0143] Table 1 - Performance Data Table

[0144] Data Analysis:

[0145] Comparative analysis of the data in Table 1 above shows that the bulk density of the coating composition prepared by this invention is 0.6 g·cm³. -3 The permanent linear change upon heating is -0.2%, the compressive strength at room temperature is 3.8 MPa, and the thermal conductivity is 0.15 W·(m·K). -1 ;

[0146] By comparing the data of Example 12 and Comparative Example 1, it can be found that the composite top cover brick prepared in Example 12 has a significantly reduced permanent linear change at heating and a significantly improved compressive strength at room temperature. This indicates that in the process of preparing heat-resistant fibers, the addition of conductive carbon black in Example 12 significantly improves the overall conductivity of the spinning solution. During electrospinning, it facilitates the formation of sprayed fibers under high voltage, forming a structurally stable heat-resistant fiber precursor. During calcination, the carbon black is pyrolyzed to form a stable porous structure by controlling the temperature, and active hydroxyl structures with active functional groups are formed on its surface by high-temperature water vapor modification. Thus, in the process of preparing heat-resistant aerogels, modified refractory materials, and composite binders, its rich porous structure and surface active functional group hydroxyl groups form a tight cross-linked support structure with the material, significantly improving the structural stability of the material and significantly improving the permanent linear change at heating and compressive strength at room temperature of the composite top cover brick.

[0147] By comparing the data of Example 12 and Comparative Example 1, it can be found that the volume density and thermal conductivity of the composite top cover brick prepared in Example 12 are significantly reduced. This indicates that in the process of preparing the composite top cover brick in Example 12, a structurally stable heat-resistant aerogel is prepared by hydrolyzing the siloxy groups on the surface of the modified hollow spheres and the heat-resistant fibers modified with high-porosity active functional groups. The microstructure of the heat-resistant aerogel is composed of a very fine and continuous network-like solid framework. These microstructures greatly reduce the actual volume of the material while maintaining the integrity of the material. In synergy with the hollow structure of the modified hollow spheres, the volume density of the composite top cover brick is reduced. Furthermore, the air layer inside the heat-resistant aerogel and the modified glass spheres can significantly reduce the transfer of heat energy through the material, and significantly reduce the thermal conductivity of the composite top cover brick.

[0148] By comparing the data of Example 12 and Comparative Example 1, it can be found that the composite top cover brick prepared in Example 12 has a significantly reduced permanent linear change due to heating and a significantly improved room temperature compressive strength. This indicates that the composite top cover brick prepared in Example 12 uses a composite adhesive with a heat-resistant fiber as the support structure, which is a mixture of bisphenol A type epoxy resin and hydroxyl polysiloxane. Compared with the direct use of bisphenol A type epoxy resin, the composite adhesive is internally supported by heat-resistant fibers and modified by hydroxyl polysiloxane, which reduces the coefficient of thermal expansion of the material, improves its dimensional stability under temperature changes, reduces the permanent linear change due to heating of the composite top cover brick, and enhances the overall mechanical properties of bisphenol A type epoxy resin by heat-resistant fibers, thereby improving the structural stability of the composite adhesive, helping to maintain the structural integrity of the material, and improving the room temperature compressive strength of the material.

[0149] This invention involves introducing conductive carbon black during the electrospinning process to prepare heat-resistant fibers. After improving process efficiency, calcination is used to remove the carbon structure and introduce hydroxyl groups to increase the contact area and reactivity between the heat-resistant fibers and other auxiliary materials. This carbon black then serves as the skeleton structure for heat-resistant aerogels, modified refractory materials, and composite binders, improving the composite performance of the materials. Finally, after mixing and pressing, a lightweight, high-temperature resistant, and pressure-resistant composite roof brick with thermal insulation properties is obtained.

[0150] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A composite tin bath top cover brick with thermal insulation properties, characterized in that, It comprises the following raw materials in parts by weight: 80-100 parts modified refractory, 15-20 parts heat-resistant aerogel, 10-15 parts composite binder, 5-8 parts water glass and 8-10 parts silica sand; The preparation method of modified refractory materials includes the following steps: A1. Add ultrafine calcined kaolin, heat-resistant fiber, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, deionized water and sodium hydroxide powder to a reaction vessel and stir. Raise the temperature of the reaction vessel to 60-80℃, keep it at the temperature and stir for 20-40 minutes, and then process to obtain refractory material. A2. After pressing the refractory material into shape, transfer it to a muffle furnace and calcine it to obtain modified refractory material; The method for preparing the heat-resistant aerogel includes the following steps: B1. Add modified hollow spheres, heat-resistant fibers and deionized water to a reaction vessel. Stir at room temperature for 10-15 minutes. After the temperature of the reaction vessel is raised to 80-90℃, stop stirring. Adjust the pH of the system to 8-10 using saturated sodium hydroxide solution. Keep the reaction at this temperature for 2-3 hours to obtain a composite gel. B2. After transferring the composite gel into a stainless steel mold, the stainless steel mold is transferred to a copper column immersed in liquid nitrogen and left to stand for 20-30 minutes. The heat-resistant aerogel is then obtained through post-treatment. The preparation method of modified hollow spheres includes the following steps: C1. Add hollow glass microspheres and 2-4wt% sodium hydroxide aqueous solution to a reaction vessel and stir. Raise the temperature of the reaction vessel to 60-80℃ and keep it at this temperature for 1-2 hours. Then, after post-treatment, etched microspheres are obtained. C2. Add the etched microspheres, triethylamine and N,N-dimethylformamide to the reaction vessel, purge with nitrogen for protection, add the modification solution to the reaction vessel, react for 40-60 min, and then perform post-treatment to obtain modified hollow spheres; The method for preparing the heat-resistant fiber includes the following steps: D1. Add aluminum chloride hexahydrate, methyl orthosilicate and deionized water to the reaction vessel, stir at room temperature for 10-15 minutes, then add auxiliary agent and conductive carbon black to the reaction vessel to obtain spinning solution. D2. Add the spinning solution to the electrospinning machine and obtain the heat-resistant fiber precursor by electrospinning. D3. The heat-resistant fiber precursor is transferred to a tube furnace and calcined to obtain heat-resistant fiber. The composite adhesive is prepared as follows: bisphenol A type epoxy resin, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, triethylamine and acetone are added to a reaction vessel and stirred. The temperature of the reaction vessel is raised to 60-80℃ and stirred for 20-40 min. Then, heat-resistant fiber and hydroxyl polysiloxane are added to the reaction vessel and stirred for 10-15 min. Finally, saturated sodium hydroxide solution is added to the reaction vessel to adjust the pH of the system to 8-10. The reaction is carried out for 1-2 h, and the composite adhesive is obtained after post-treatment.

2. The composite tin bath top cover brick with thermal insulation as described in claim 1, characterized in that, In step A1, the ratio of ultrafine calcined kaolin, heat-resistant fiber, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, deionized water, and sodium hydroxide powder is 8-10g:1-2g:0.5-0.8g:20-30mL. In step A2, the calcination operation is as follows: after nitrogen protection is introduced into the muffle furnace, the muffle furnace is heated to 1350-1600℃ at a heating rate of 5-8℃ / min, the reaction is held at this temperature for 4-6 hours, and then naturally cooled to room temperature to obtain the modified refractory.

3. The composite tin bath top cover brick with thermal insulation as described in claim 1, characterized in that, In step C1, the ratio of hollow glass microspheres to 2-4 wt% sodium hydroxide aqueous solution is 1-2 g: 10-15 mL, and the stirring speed of the reaction vessel is 80-120 rpm. In step C2, the ratio of etching microspheres, triethylamine, N,N-dimethylformamide and modification solution is 4-5 g: 0.5-0.8 g: 15-18 mL: 8-10 mL, and the modification solution is obtained by mixing 3-isocyanate-propyltrimethoxysilane and N,N-dimethylformamide at a ratio of 1-2 g: 5 mL.

4. The composite tin bath top cover brick with thermal insulation as described in claim 1, characterized in that, In step D1, the ratio of aluminum chloride hexahydrate, methyl orthosilicate, deionized water, auxiliary agent, and conductive carbon black is 12-15g:6-8g:40-50mL:12-16g:3-5g. The auxiliary agent is a mixture of aluminum isopropoxide, acetic acid, and polyvinylpyrrolidone in a ratio of 12-16g:2-3g:1-2g. In step D2, the electrospinning voltage is 20-24kV, the receiving distance is 20-25cm, the infusion rate is 6-8mL / h, the sliding table moving speed is 25-30cm / min, and the receiving roller rotation speed is 25-30r / min.

5. The composite tin bath top cover brick with thermal insulation as described in claim 1, characterized in that, In step D3, the calcination operation includes the following steps: After nitrogen protection is introduced into the tubular furnace, the temperature of the tubular furnace is raised to 600-650℃ at a heating rate of 5-6℃ / min. The nitrogen is then turned off, and oxygen is introduced at a flow rate of 1-2L / min. After holding at this temperature for 1-2 hours, the oxygen is turned off, and nitrogen is introduced again. The temperature is then raised to 1250-1350℃ at a heating rate of 5-6℃ / min. After holding at this temperature for 1-2 hours, the temperature is allowed to cool naturally to 100-120℃. The nitrogen is then turned off, and water vapor is introduced at a flow rate of 1-3L / min. After holding at this temperature for 1-2 hours, heat-resistant fibers are obtained.

6. A method for preparing a thermally insulating composite tin bath top cover brick according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Add the modified refractory, heat-resistant aerogel and silica sand to a pulverizer, pulverize and pass through a 400-600 mesh sieve to obtain a mixture; S2. After adding the mixture into the homogenizer, add the composite binder into the homogenizer, homogenize and mix for 8-10 minutes, then add water glass and continue homogenizing and mixing for 5-6 minutes. Discharge and press into bricks. S3. Transfer the bricks to a drying kiln at 250-270℃ for drying for 24-36 hours. After cooling, the composite top cover bricks are obtained.

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