Aluminum silicate thermal insulation material and preparation method thereof

Abstract

The invention belongs to the technical field of thermal insulation materials, and particularly relates to an aluminum silicate thermal insulation material and a preparation method thereof. The aluminum silicate thermal insulation material is prepared from the following raw materials in parts by weight: 60 to 80 parts of aluminum silicate fiber, 5 to 15 parts of polyvinyl alcohol fiber, 15 to 25 parts of function enhanced compound and 8 to 12 parts of silica sol, the polyvinyl alcohol fiber provides flexible bonding for the aluminum silicate fiber in the initial preparation stage, and the brittleness is improved; functional enhanced compound particles are dispersed in a fiber network, and a rigid framework of the functional enhanced compound particles and a flexible support of fibers form rigid-flexible complementation, so that the compression resistance is improved. The surface active sites of the silicon carbide aerogel activated and modified in the function enhancing compound are increased, the silicon carbide aerogel can be stably combined with polyimide chopped fibers through chemical bonds, and a compact interface layer can be constructed by means of permeation and coating of boehmite sol; the prepared aluminum silicate thermal insulation material has excellent thermal insulation effect and stable mechanical property.

Description

Technical Field

[0001] This invention belongs to the field of thermal insulation materials technology, specifically relating to an aluminum silicate thermal insulation material and its preparation method. Background Technology

[0002] Aluminum silicate insulation materials, due to their advantages such as high temperature resistance, good chemical stability, and wide availability, have become an indispensable core insulation material in fields such as industrial furnaces, building energy conservation, and new energy equipment. Their performance directly affects the energy efficiency, operational safety, and service life of end products. With the deepening of energy conservation and environmental protection policies and the development of high-end manufacturing, the market has placed higher demands on the comprehensive performance of aluminum silicate insulation materials. These materials not only require excellent thermal insulation effects but also need to consider multiple characteristics such as lightweight, mechanical strength, resistance to damp heat, and high-temperature dimensional stability.

[0003] In existing technologies, the preparation of aluminosilicate insulation materials mostly uses aluminosilicate minerals as the base raw material and is produced through conventional processes such as mixing, molding, and sintering. However, these technologies generally suffer from performance bottlenecks that are difficult to overcome. Regarding insulation performance, traditional materials often rely on a single micron-sized pore structure to achieve thermal insulation. Limited by pore control technology, the potential for reducing thermal conductivity is limited, and excessively high pore connectivity can easily lead to a decline in insulation performance. Therefore, the current field of aluminosilicate insulation materials urgently needs a technical solution that can synergistically improve both insulation performance and mechanical strength to meet the pressing needs of various industries for high-end insulation materials. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an aluminosilicate insulation material and its preparation method. This invention constructs an integrated insulation and toughening structure through a functionally enhanced composite, which both reduces thermal conductivity to ensure insulation performance and improves the material's mechanical strength, resolving the performance contradictions of traditional materials. Simultaneously, the synergistic effect of the boehmite sheath and the carbonized fiber skeleton significantly improves the material's high-temperature dimensional stability and resistance to damp heat, inhibiting high-temperature shrinkage and mechanical softening in humid environments. This solves the technical problems of existing aluminosilicate insulation materials, such as the mutual constraint between insulation and mechanical properties, uneven dispersion of functional components, weak interfacial bonding, and poor performance stability under high-temperature environments. The aluminosilicate insulation material prepared by this invention possesses excellent thermal insulation performance, stable mechanical properties, and good environmental adaptability, making it widely applicable to various fields such as building energy conservation, industrial furnaces, and new energy equipment. 。

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows: This invention provides an aluminum silicate insulation material, which comprises the following raw materials in parts by weight: 60-80 parts aluminum silicate fiber, 5-15 parts polyvinyl alcohol fiber, 15-25 parts functional reinforcing composite, 8-12 parts silica sol, and 0.1-0.3 parts anionic polyacrylamide. The functional enhancement composite comprises raw materials in the following mass ratio: silicon carbide aerogel powder: polyimide chopped fibers: boehmite sol: silane coupling agent: anionic dispersant = 10-12: 5: 30: 0.2: 0.05; The method for preparing the functionally enhanced complex includes the following steps: (1) Take silicon carbide aerogel powder and heat-treat it at 600°C for 1 hour in air atmosphere to activate it. Disperse the activated silicon carbide aerogel in toluene with a ratio of silicon carbide aerogel to toluene of 1g:5mL. Add silane coupling agent and reflux at 110°C for 4 hours. After the reaction is completed, filter and wash with toluene. Dry at 80°C to obtain modified silicon carbide aerogel. (2) Disperse polyimide short fibers in deionized water. The ratio of polyimide short fibers to deionized water is 1g:40mL. Add an anionic dispersant and stir at high speed for 1 hour to form a uniform fiber suspension. Under strong stirring, slowly and in batches add modified silicon carbide aerogel to the fiber suspension and continue stirring for 2 hours. Then let it stand for 12 hours and filter under vacuum to obtain wet composite felt. (3) The wet composite felt is completely immersed in boehmite sol and kept under a vacuum of 0.1 MPa for 30 minutes to ensure that the sol fully penetrates into every pore of the composite. The impregnated composite felt is then removed, placed in a sealed container, aged at 80°C for 24 hours, and dried at 105°C for 24 hours to obtain a dried precast reinforced block. The dried block is then gently crushed under a protective airflow, sieved, and particles with a particle size between 0.5 and 2.0 mm are selected to obtain the functional composite reinforcement.

[0006] Furthermore, the boehmite sol comprises raw materials in the following mass ratio: isopropanol:aluminum isopropoxide = 1:7-8; The preparation process of the boehmite sol is as follows: Isopropanol and aluminum isopropoxide are added to a dry three-necked flask. The flask is placed in an oil bath, a condenser and a stirrer are installed, the stirrer is turned on and the temperature is heated to 85°C until the aluminum isopropoxide is completely dissolved, resulting in a clear solution. The oil bath temperature is maintained at 85°C. Using a constant pressure dropping funnel, 54.0 g of deionized water is slowly added dropwise to the above solution at a rate of about 1-2 drops / second. After the deionized water is added, the temperature is maintained at 85°C and the stirring is continued vigorously. The reaction is refluxed for 24 hours. After the reaction is completed, the heating is stopped and the system is cooled to room temperature. Dilute nitric acid solution is added dropwise to the obtained boehmite slurry while stirring. When the pH of the system is 3.5-4.0, the above sol is transferred to a petri dish and placed in a constant temperature drying oven at 60°C with the opening open. The dish is weighed periodically and filtered to obtain the boehmite sol.

[0007] Furthermore, the silane coupling agent is one of KH-550, KH-560, and KH-570.

[0008] Furthermore, the anionic dispersant is polyacrylate or polyphosphate.

[0009] This invention also provides a method for preparing aluminum silicate insulation material, specifically including the following steps: S1. In a large hydraulic pulper, add deionized water and heat to 60-70 ℃. Add polyvinyl alcohol fiber, with a mass ratio of polyvinyl alcohol fiber to deionized water of 1:60. Stir at 600 rpm for 30 minutes until completely dissolved to form a transparent or translucent uniform slurry. Stop heating and add deionized water to the slurry, with a volume ratio of deionized water to slurry of 3-5:1. Stir rapidly to lower the temperature of the slurry to below 50 ℃. Add aluminum silicate fiber and increase the pulper speed. Continue pulping for 40 minutes to form a highly uniform and stable fiber suspension slurry. S2, reduce the speed of the pulper to 400 rpm, slowly and evenly add the functional enhancement complex, and continue stirring at this speed for 15 minutes to form a mixed pulp; S3, pump the mixed slurry into the front box of the paper forming machine, and add anionic polyacrylamide at 0.1%-0.3% of the total mass of the mixed slurry as a flocculant. Adjust the slurry concentration and flow rate, and filter water on the forming screen to form a uniform wet blank. S4. The wet blank is passed through an impregnation tank containing silica sol with a SiO2 content of 5-10%. Excess sol is removed by a slight squeezing roller, so that the silica sol is evenly distributed in the wet blank as a second binder. The wet blank is then fed into a multi-layer conveyor dryer and dried in stages at 90-120℃ until the moisture content is <1%, to obtain a dry blank. S5. The dry blank is fed into a programmable temperature controlled sintering furnace and subjected to the following process: heating from room temperature to 300°C at a heating rate of 1-2°C / min, then heating from 300°C to 500-700°C at a heating rate of 2°C / min to decompose organic matter, and holding at this temperature for 1 hour, then heating from this temperature to 800°C at a heating rate of 3°C / min, and holding at 800°C for 1 hour to activate inorganic phases, and finally heating from 800°C to 1100-1200°C at a heating rate of 5°C / min, and holding at this temperature for 2 hours to perform mullite sintering, and then cooling with the furnace to room temperature to obtain aluminum silicate insulation material.

[0010] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: This invention achieves a breakthrough improvement in the comprehensive performance of thermal insulation materials through the precise formulation of an aluminosilicate fiber matrix, a functional reinforcing composite, organic fibers, and inorganic binders. The activated and coupling agent-modified silicon carbide aerogel within the functional reinforcing composite exhibits increased surface active sites. It can form a stable bond with polyimide chopped fibers through chemical bonds and also construct a dense interface layer through the penetration and encapsulation of boehmite sol. Under vacuum impregnation, the boehmite sol fills the gaps between the aerogel and fibers, forming a sheath structure after aging and gelation. This sheath structure not only fixes the aerogel particles to prevent agglomeration and detachment but also transforms into an inorganic rigid phase at high temperatures to strengthen the skeleton. In the overall material system, polyvinyl alcohol fibers dissolve to form a glue solution in the early stages of preparation, providing flexible bonding for the aluminosilicate fibers and improving the brittleness of traditional aluminosilicate materials. The functional reinforcing composite particles are uniformly dispersed in the fiber network, and their rigid skeleton and the flexible support of the fibers form a complementary rigid-flexible structure, significantly improving the material's compressive and flexural strength. Silane coupling agents, through chemical bonding, connect the inorganic surfaces of aerogel and boehmite at one end and bind to the organic groups of polyimide at the other end, strengthening the interfacial bonding between components. The segmented sintering process further amplifies the synergistic effect of the materials. At low temperatures, the slow decomposition of polyvinyl alcohol and polyimide is achieved, avoiding structural damage caused by violent gas generation. At medium and high temperatures, boehmite transforms into an alumina phase, reacting in situ with aluminosilicate fibers to generate a mullite crystal phase, strengthening the matrix framework. The aluminosilicate insulation material ultimately prepared by this invention achieves systematic improvements in insulation performance, mechanical properties, high-temperature resistance, and structural stability. It retains the high-temperature resistance advantages of traditional aluminosilicate materials while overcoming their brittleness and low upper limit of insulation performance, while also expanding the application possibilities of the material in various scenarios such as construction and industrial furnaces. Attached Figure Description

[0011] Figure 1 This is a cross-sectional schematic diagram of the aluminum silicate material prepared according to the present invention; Figure 2 The graph shows the water absorption rate and softening coefficient of the aluminum silicate material prepared in this invention. Detailed Implementation

[0012] To enable those skilled in the art to better understand the technical solutions of the present invention and to make the above-mentioned features, objectives, and advantages of the present invention clearer and easier to understand, the present invention will be further described below with reference to embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0013] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0014] Unless otherwise specified, all methods used in the following examples are conventional. Unless otherwise specified, all materials used in the following examples are new materials purchased from the market. Among them, the polyvinyl alcohol fiber with a tensile strength of 1560MPa and an elastic modulus of 41GPa was purchased from Kuraray Co., Ltd. of Japan; the polyimide chopped strand fiber, model: S0T, with a relative density of 1.41g / cm3, a tensile strength of 3.5GPa, and a tensile modulus of 120GPa, was purchased from Jiangsu Xiannuo New Material Technology Co., Ltd.

[0015] Example 1: This example provides an aluminum silicate insulation material, which includes the following raw materials in parts by weight: 60 parts aluminum silicate fiber, 5 parts polyvinyl alcohol fiber, 15 parts functional reinforcing composite, 8 parts silica sol, and 0.1 parts anionic polyacrylamide. The functional enhancement composite comprises raw materials in the following mass ratio: silicon carbide aerogel powder: polyimide chopped fibers: boehmite sol: KH-550: ammonium polyacrylate = 10:5:30:0.2:0.05; The method for preparing the functionally enhanced complex includes the following steps: (1) Take silicon carbide aerogel powder and heat-treat it at 600°C for 1 hour in air atmosphere to activate it. Disperse the activated silicon carbide aerogel in toluene with a ratio of silicon carbide aerogel to toluene of 1g:5mL. Add silane coupling agent and reflux at 110°C for 4 hours. After the reaction is completed, filter and wash with toluene. Dry at 80°C to obtain modified silicon carbide aerogel. (2) Disperse polyimide short chopped fibers in deionized water. The ratio of polyimide short chopped fibers to deionized water is 1g:40mL. Add ammonium polyacrylate and stir at 2000rpm for 1 hour to form a uniform fiber suspension. Under strong stirring, slowly and in batches add modified silicon carbide aerogel to the fiber suspension and continue stirring for 2 hours. Then let it stand for 12 hours and filter under vacuum to obtain wet composite felt. (3) The wet composite felt is completely immersed in boehmite sol and kept under a vacuum of 0.1 MPa for 30 minutes to ensure that the sol fully penetrates into every pore of the composite. The impregnated composite felt is then removed, placed in a sealed container, aged at 80°C for 24 hours, and dried at 105°C for 24 hours to obtain a dried precast reinforced block. The dried precast reinforced block is then gently crushed under a protective airflow, sieved, and particles with a particle size between 0.5 and 2.0 mm are selected to obtain the functional reinforced composite.

[0016] The boehmite sol comprises the following raw materials in the following mass ratio: isopropanol:aluminum isopropoxide = 1:7; The preparation process of the boehmite sol is as follows: Isopropanol and aluminum isopropoxide are added to a dry three-necked flask. The flask is placed in an oil bath, a condenser and a stirrer are installed, and stirring is started while heating to raise the oil bath temperature to 85°C until the aluminum isopropoxide is completely dissolved, resulting in a clear solution. The oil bath temperature is maintained at 85°C. Deionized water is slowly added dropwise to the clear solution at a rate of 1 drop / second using a constant pressure dropping funnel. The mass ratio of deionized water to aluminum isopropoxide is 15:7. After the deionized water is added, the temperature is maintained at 85°C. Continue vigorous stirring and reflux for 24 hours. After the reaction is complete, stop heating and cool the system to room temperature. Add a 5% dilute nitric acid solution dropwise to the obtained boehmite slurry while stirring. When the pH of the system is about 3.5, transfer the sol to a petri dish and place it in a 60°C constant temperature drying oven with the opening open to allow excess isopropanol and water to evaporate slowly. Weigh the sol periodically and filter it using a 0.45μm pore size polyethersulfone filter to obtain a clear, light blue boehmite sol.

[0017] This embodiment also provides a method for preparing aluminum silicate thermal insulation material, which specifically includes the following steps: S1. In a large hydraulic pulper, add deionized water and heat to 60°C. Add polyvinyl alcohol fiber, with a mass ratio of polyvinyl alcohol fiber to deionized water of 1:60. Stir at 600 rpm for 30 minutes until completely dissolved to form a transparent or translucent uniform slurry. Stop heating and add deionized water to the slurry, with a volume ratio of deionized water to slurry of 3:1. Stir rapidly to lower the temperature of the slurry to below 50°C. Add aluminosilicate fiber and increase the pulper speed to 1000 rpm. Continue pulping for 40 minutes to form a highly uniform and stable fiber suspension slurry. S2, reduce the pulper speed to 400 rpm, slowly and evenly add the functional reinforcing compound, and continue stirring at this speed for 15 minutes to ensure that the reinforcing particles are completely wetted and evenly dispersed by the slurry, avoiding high-speed shearing that damages their structure and forming a mixed slurry; S3, the mixed slurry is pumped into the front box of the paper forming machine, and anionic polyacrylamide accounting for 0.1% of the total mass of the mixed slurry is added as a flocculant. The slurry concentration and flow rate are adjusted. The slurry is filtered on the forming screen to form a continuous wet felt and a uniform wet blank. It is then further dehydrated through a vacuum dewatering box to make the wet blank dryness reach 35%. S4. The wet blank is passed through an impregnation tank containing silica sol with a SiO2 content of 5%. Excess sol is removed by a slight squeezing roller, so that the silica sol is evenly distributed in the wet blank as a second binder. The wet blank is then fed into a multi-layer crawler dryer and dried in sections at 90°C until the moisture content is <1%, to obtain a dry blank. S5. The dry blank is fed into a programmable temperature controlled sintering furnace and the following process is performed: heating from room temperature to 300°C at a heating rate of 1°C / min, then heating from 300°C to 500°C at a heating rate of 2°C / min to decompose organic matter, and holding at this temperature for 1 hour, then heating from 500°C to 800°C at a heating rate of 3°C / min, and holding at 800°C for 1 hour to activate inorganic phase, and finally heating from 800°C to 1100°C at a heating rate of 5°C / min, and holding at this temperature for 2 hours to perform mullite sintering, and then cooling with the furnace to room temperature to obtain aluminum silicate insulation material.

[0018] Example 2: This example provides an aluminum silicate insulation material, which comprises the following raw materials in parts by weight: 70 parts aluminum silicate fiber, 10 parts polyvinyl alcohol fiber, 20 parts functional reinforcing composite, 10 parts silica sol, and 0.2 parts anionic polyacrylamide. The functional enhancement composite comprises raw materials in the following mass ratio: silicon carbide aerogel powder: polyimide chopped fibers: boehmite sol: KH-560: sodium polyacrylate = 11:5:30:0.2:0.05; The method for preparing the functionally enhanced complex includes the following steps: (1) Take silicon carbide aerogel powder and heat-treat it at 600℃ for 1 hour in air atmosphere to activate it. Disperse the activated silicon carbide aerogel in toluene with a ratio of silicon carbide aerogel to toluene of 1g:5mL. Add KH-560 and reflux at 110℃ for 4 hours. After the reaction is completed, filter and wash with toluene. Dry at 80℃ to obtain modified silicon carbide aerogel. (2) Disperse polyimide short chopped fibers in deionized water. The ratio of polyimide short chopped fibers to deionized water is 1g:40mL. Add sodium polyacrylate and stir at 2000rpm for 1 hour to form a uniform fiber suspension. Under strong stirring, slowly and in batches add modified silicon carbide aerogel to the fiber suspension and continue stirring for 2 hours. Then let it stand for 12 hours and filter under vacuum to obtain wet composite felt. (3) The wet composite felt is completely immersed in boehmite sol and kept under a vacuum of 0.1 MPa for 30 minutes to ensure that the sol fully penetrates into every pore of the composite. The impregnated composite felt is then removed, placed in a sealed container, aged at 80°C for 24 hours, and dried at 105°C for 24 hours to obtain a dried precast reinforced block. The dried block is then gently crushed under a protective airflow, sieved, and particles with a particle size between 0.5 and 2.0 mm are selected to obtain the functional reinforced composite.

[0019] The boehmite sol comprises raw materials in the following mass ratio: isopropanol:aluminum isopropoxide = 1:7.5; The preparation process of the boehmite sol is as follows: Isopropanol and aluminum isopropoxide are added to a dry three-necked flask. The flask is placed in an oil bath, a condenser and a stirrer are installed, and stirring is started while heating to raise the oil bath temperature to 85°C until the aluminum isopropoxide is completely dissolved, resulting in a clear solution. The oil bath temperature is maintained at 85°C. Deionized water is slowly added dropwise to the clear solution at a rate of 2 drops / second using a constant pressure dropping funnel. The mass ratio of deionized water to aluminum isopropoxide is 15:7. After the deionized water is added, the temperature is maintained at 85°C. Continue vigorous stirring and reflux for 24 hours. After the reaction is complete, stop heating and cool the system to room temperature. Add a 6% dilute nitric acid solution dropwise to the obtained boehmite slurry while stirring. When the pH of the system is about 4.0, transfer the sol to a petri dish and place it in a 60°C constant temperature drying oven with the opening open to allow excess isopropanol and water to evaporate slowly. Weigh the sol periodically and filter it using a 0.45μm pore size polyethersulfone filter to obtain a clear, light blue boehmite sol.

[0020] This embodiment also provides a method for preparing aluminum silicate thermal insulation material, which specifically includes the following steps: S1. In a large hydraulic pulper, deionized water is added and heated to 65°C. Polyvinyl alcohol fibers are added, with a mass ratio of polyvinyl alcohol fibers to deionized water of 1:60. The mixture is stirred at 600 rpm for 30 minutes until it is completely dissolved to form a transparent or translucent uniform slurry. Heating is stopped, and deionized water is added to the slurry, with a volume ratio of deionized water to slurry of 4:1. The mixture is stirred rapidly to lower the temperature of the slurry to below 50°C. Aluminum silicate fibers are added, and the pulper speed is increased to 1000 rpm. Pulping is continued for 40 minutes to form a highly uniform and stable fiber suspension slurry. S2, reduce the pulper speed to 400 rpm, slowly and evenly add the functional reinforcing compound, and continue stirring at this speed for 15 minutes to ensure that the reinforcing particles are completely wetted and evenly dispersed by the slurry, avoiding high-speed shearing that damages their structure and forming a mixed slurry; S3, the mixed slurry is pumped into the front box of the paper forming machine, and anionic polyacrylamide accounting for 0.2% of the total mass of the mixed slurry is added as a flocculant. The slurry concentration and flow rate are adjusted. The slurry is filtered on the forming screen to form a continuous wet felt and a uniform wet blank. It is then further dehydrated through a vacuum dewatering box to make the wet blank dryness reach 40%. S4. The wet blank is passed through an impregnation tank containing silica sol with a SiO2 content of 8%. Excess sol is removed by a slight extrusion roller, so that the silica sol is evenly distributed in the wet blank as a second binder. The wet blank is then fed into a multi-layer conveyor dryer and dried in sections at 100°C until the moisture content is <1%, thus obtaining a dry blank. S5. The dry blank is fed into a programmable temperature controlled sintering furnace and the following process is performed: heating from room temperature to 300°C at a heating rate of 2°C / min, then heating from 300°C to 550°C at a heating rate of 2°C / min to decompose organic matter, and holding at this temperature for 1 hour, then heating from 550°C to 800°C at a heating rate of 3°C / min, and holding at 800°C for 1 hour to activate inorganic phase, and finally heating from 800°C to 1150°C at a heating rate of 5°C / min, and holding at this temperature for 2 hours to perform mullite sintering, and then cooling with the furnace to room temperature to obtain aluminum silicate insulation material.

[0021] Example 3: This example provides an aluminum silicate insulation material, which comprises the following raw materials in parts by weight: 80 parts aluminum silicate fiber, 15 parts polyvinyl alcohol fiber, 25 parts functional reinforcing composite, 12 parts silica sol, and 0.3 parts anionic polyacrylamide. The functional enhancement composite comprises raw materials in the following mass ratio: silicon carbide aerogel powder: polyimide chopped fibers: boehmite sol: KH-570: sodium hexametaphosphate = 12:5:30:0.2:0.05; The method for preparing the functionally enhanced complex includes the following steps: (1) Take silicon carbide aerogel powder and heat-treat it at 600℃ for 1 hour in air atmosphere to activate it. Disperse the activated silicon carbide aerogel in toluene with a ratio of silicon carbide aerogel to toluene of 1g:5mL. Add KH-570 and reflux at 110℃ for 4 hours. After the reaction is completed, filter and wash with toluene. Dry at 80℃ to obtain modified silicon carbide aerogel. (2) Disperse polyimide short fibers in deionized water. The ratio of polyimide short fibers to deionized water is 1g:40mL. Add sodium polyphosphate and stir at 2000rpm for 1 hour to form a uniform fiber suspension. Under strong stirring, slowly and in batches add modified silicon carbide aerogel to the fiber suspension and continue stirring for 2 hours. Then let it stand for 12 hours and filter under vacuum to obtain wet composite felt. (3) The wet composite felt is completely immersed in boehmite sol and kept under a vacuum of 0.1 MPa for 30 minutes to ensure that the sol fully penetrates into every pore of the composite. The impregnated composite felt is then removed, placed in a sealed container, aged at 80°C for 24 hours, and dried at 105°C for 24 hours to obtain a dried precast reinforced block. The dried block is then gently crushed under a protective airflow, sieved, and particles with a particle size between 0.5 and 2.0 mm are selected to obtain the functional reinforced composite.

[0022] The boehmite sol comprises the following raw materials in the following mass ratio: isopropanol:aluminum isopropoxide = 1:8; The preparation process of the boehmite sol is as follows: Isopropanol and aluminum isopropoxide are added to a dry three-necked flask. The flask is placed in an oil bath, a condenser and a stirrer are installed, and stirring is started while heating to raise the oil bath temperature to 85°C until the aluminum isopropoxide is completely dissolved, resulting in a clear solution. The oil bath temperature is maintained at 85°C. Deionized water is slowly added dropwise to the clear solution at a rate of 2 drops / second using a constant pressure dropping funnel. The mass ratio of deionized water to aluminum isopropoxide is 15:7. After the deionized water is added, the temperature is maintained at 85°C. Continue vigorous stirring and reflux for 24 hours. After the reaction is complete, stop heating and cool the system to room temperature. Add a 7% dilute nitric acid solution dropwise to the obtained boehmite slurry while stirring. When the pH of the system is about 4.0, transfer the sol to a petri dish and place it in a 60°C constant temperature drying oven with the opening open to allow excess isopropanol and water to evaporate slowly. Weigh the sol periodically and filter it using a 0.45μm pore size polyethersulfone filter to obtain a clear, light blue boehmite sol.

[0023] This embodiment also provides a method for preparing aluminum silicate thermal insulation material, which specifically includes the following steps: S1. In a large hydraulic pulper, deionized water is added and heated to 70°C. Polyvinyl alcohol fibers are added, with a mass ratio of 1:60 between the polyvinyl alcohol fibers and deionized water. The mixture is stirred at 600 rpm for 30 minutes until it is completely dissolved to form a transparent or translucent homogeneous slurry. Heating is stopped, and deionized water is added to the slurry at a volume ratio of 5:1 between the deionized water and the slurry. The mixture is stirred rapidly to lower the temperature of the slurry to below 50°C. Aluminum silicate fibers are added, and the pulper speed is increased to 1000 rpm. Pulping is continued for 40 minutes to form a highly uniform and stable fiber suspension slurry. S2, reduce the pulper speed to 400 rpm, slowly and evenly add the functional reinforcing compound, and continue stirring at this speed for 15 minutes to ensure that the reinforcing particles are completely wetted and evenly dispersed by the slurry, avoiding high-speed shearing that damages their structure and forming a mixed slurry; S3, the mixed slurry is pumped into the front box of the paper forming machine, and anionic polyacrylamide accounting for 0.3% of the total mass of the mixed slurry is added as a flocculant. The slurry concentration and flow rate are adjusted. The slurry is filtered on the forming screen to form a continuous wet felt and a uniform wet blank. It is then further dehydrated through a vacuum dewatering box to make the wet blank dryness reach 40%. S4. The wet blank is passed through an impregnation tank containing silica sol with a SiO2 content of 10%. Excess sol is removed by a slight squeezing roller, so that the silica sol is evenly distributed in the wet blank as a second binder. The wet blank is then fed into a multi-layer crawler dryer and dried in sections at 120°C until the moisture content is <1%, thus obtaining a dry blank. S5. The dry blank is fed into a programmable temperature controlled sintering furnace and the following process is performed: heating from room temperature to 300°C at a heating rate of 2°C / min, then heating from 300°C to 700°C at a heating rate of 2°C / min to decompose organic matter, and holding at this temperature for 1 hour, then heating from 700°C to 800°C at a heating rate of 3°C / min, and holding at 800°C for 1 hour to activate inorganic phases, and finally heating from 800°C to 1200°C at a heating rate of 5°C / min, and holding at this temperature for 2 hours to perform mullite sintering, and then cooling to room temperature with the furnace to obtain aluminum silicate insulation material.

[0024] The difference between Comparative Example 1 and Example 2 is that no functional enhancement complex was added; the rest is exactly the same as Example 2.

[0025] The difference between Comparative Example 2 and Example 2 is that silicon carbide aerogel is not added; the rest is exactly the same as Example 2.

[0026] The difference between Comparative Example 3 and Example 2 is that polyvinyl alcohol fiber is not added; otherwise, they are exactly the same as Example 2.

[0027] Experimental example: 1. Bulk Density: Using the aluminum silicate insulation materials prepared in Examples 1-3 and Comparative Examples 1-3 of this invention as samples, three regularly shaped samples were cut from the sample material using a cutting tool. The samples were placed in an electric heating drying oven and dried at 105°C to constant weight (i.e., weighed at 2-hour intervals, with a mass change not exceeding 0.1%). Then, they were transferred to a desiccator to cool to room temperature. The mass (m) of each dried sample was weighed using an electronic balance, accurate to 0.01 g. Three measurements were taken evenly along the length, width, and thickness of the sample using vernier calipers, and the arithmetic mean of these measurements was taken as the sample's length (L), width (W), and thickness (T), accurate to 0.1 mm. The volume (V) of a single sample was calculated using the following formula: V = L × W × T; the bulk density (ρ) of a single sample was calculated using the following formula: ρ = m / V × 10 9 In the formula: ρ—bulk density, in kilograms per cubic meter (kg / m³) 3 m—sample mass, in grams (g); V—sample volume, in cubic millimeters (mm²) 3 The calculated bulk density is recorded in Table 1.

[0028] 2. Compressive Strength: Using the aluminum silicate insulation materials prepared in Examples 1-3 and Comparative Examples 1-3 of this invention as samples, the compression surface of the sample was selected, and the dimensions of the compression surface were measured using vernier calipers to calculate the cross-sectional area of ​​the sample. The sample was placed in a pressure testing machine, and a load was gradually applied at the standard loading rate until the sample failed. The maximum load was recorded, and the compressive strength was calculated based on the cross-sectional area of ​​the sample. The compressive strength was calculated using the following formula: f = F / A, where: f is the compressive strength value of the specimen, in megapascals (MPa), accurate to 0.01 MPa; F is the maximum failure load, in Newtons (N); and A is the compression area of ​​the specimen, in square millimeters (mm²). 2 The compressive strength of each group of specimens is the average of the compressive strengths of the three specimens, and the results are recorded in Table 1.

[0029] 3. Flexural Strength: Using the aluminum silicate insulation materials prepared in Examples 1-3 and Comparative Examples 1-3 of this invention as samples, and following the "GB / T17671 Test Method for Strength of Cement Mortar", standard prism specimens with dimensions of 160mm × 40mm × 40mm were used. The specimens were placed in a compression testing machine, and a load was gradually applied at the standard loading rate until the specimen failed. The maximum load was recorded, and the flexural strength was calculated using the following formula: R f =(1.5F f *L) / b 3 Wherein, in the formula: F fThe load applied to the upper middle part of the specimen at the time of fracture is expressed in Newtons (N). L is the center-to-center distance between the lower supporting cylinders. For standard clamps, L = 100 mm. b is the height and width of the specimen cross-section (40 mm), i.e., b = 64000 mm. 3 Calculate the flexural strength R f The unit is megapascal (MPa). The results are recorded in Table 1.

[0030] 4. Thermal Conductivity: The thermal conductivity was tested using the method specified in GB / T10295-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Thermal Insulation Materials". Alumina silicate insulation materials prepared in Examples 1-3 and Comparative Examples 1-3 of this invention were used as samples, cut to 200mm × 200mm × 25mm. The samples were installed in the thermal conductivity meter, ensuring good thermal contact between the sample and the heat and cold sources of the instrument. Good contact between the sample surface and the sensor was also ensured. Before the formal test, the instrument and samples were preheated for a certain period to achieve a stable working state. The heat flow method thermal conductivity meter was then started for testing. The instrument calculates the thermal conductivity by measuring the temperature difference between the heat and cold sources and the heat flow between the samples. The unit is (W·m). -1 ∙K -1 The results are recorded in Table 1.

[0031] 5. High-Temperature Shrinkage Rate: This test refers to the provisions on permanent linear changes upon heating in the national standard GB / T17911-2018 "Test Methods for Refractory Materials and Ceramic Fiber Products". Prepare three rectangular specimens from the finished material along the product forming direction (e.g., the copying direction). Recommended dimensions: length 100mm, width 50mm, thickness as per original thickness. The two end faces of the specimen should be parallel and flat, with straight edges. Dry the specimens at 110℃ to constant weight, cool to room temperature, and precisely mark two parallel lines (L0) with an 80mm interval along the specimen length using alumina coating at the center of the specimen. Accurately measure and record their initial lengths. Place the specimens flat in the uniform temperature zone of the furnace covered with clean ceramic fiber pads, ensuring a 10mm spacing between specimens and that they do not contact the inner wall of the furnace. To simulate actual use, the samples should be placed freely without any external pressure. The furnace temperature should be raised to 1000℃ of the material of this invention at a heating rate of 5℃ / min, and held at this temperature for 24 hours. After the holding period, the samples should be allowed to cool naturally to room temperature. The samples should be removed, the surface dust carefully cleaned, and the final length (L1) between the two marked lines should be measured again. The high-temperature linear shrinkage rate (ΔL) of each sample should be calculated according to the following formula, expressed as a percentage (%): ΔL=[(L0-L1) / L0]×100%; where: L0—distance between the marked lines before heating, in millimeters (mm); L1—distance between the marked lines after heating, in millimeters (mm). The results are recorded in Table 1.

[0032] Table 1: Performance Test Results of Alumina Silicate Insulation Materials

[0033] Table 1 shows that the volume density of Comparative Example 1 is higher than that of Examples 1-3, and the matrix packing is more compact. This indicates that the addition of the functional enhancement compound can increase the porous and loose structure of the aluminum silicate insulation material and avoid excessive matrix compaction. The compressive strength and flexural strength of Comparative Examples 1-3 all show a certain degree of decrease compared with Examples 1-3, indicating that the aluminum silicate insulation material prepared in the present invention provides mechanical support, enhances rigidity, and has excellent mechanical properties. The lower thermal conductivity of Examples 1-3 indicates that the added functional enhancement compound and other raw materials work synergistically to achieve good thermal insulation performance and a good thermal insulation effect. The high-temperature shrinkage rate of Examples 1-3 is much lower than that of the comparative examples, further demonstrating the good thermal insulation performance of the aluminum silicate material, which can still maintain structural stability at high temperatures, taking into account both thermal insulation and durability.

[0034] Figure 1 The image shows that the functionally reinforced composite particles are uniformly dispersed within a continuous aluminosilicate fiber matrix. Within the magnified view of the functionally reinforced composite particles, polyimide fibers form a flexible skeleton core, its surface encapsulated by a dense sheath layer formed by boehmite sol, firmly fixing silicon carbide aerogel within. This structure ensures the integrity of the reinforcement during subsequent processing and use. Between the boehmite sheath layer of the reinforcing particles and the outer aluminosilicate matrix, there exists a mullite-treated interface, a transition layer of a certain thickness composed of interwoven fine whiskers. This indicates the specific heat treatment regime of this invention, where the boehmite undergoes an in-situ solid-state reaction with the silica in the matrix, achieving a strong and tough bond between the reinforcing particles and the matrix. Figure 2 Examples 1-3, due to the closed pores of the boehmite sheath, the hydrophobic properties of the modified aerogel, and the dense bonding of the silica sol, exhibit significantly lower water absorption rates than the comparative examples, with softening coefficients close to 0.9, demonstrating excellent resistance to damp heat. Comparative Example 1, lacking the functional enhancement composite, has numerous interconnected pores, resulting in severe degradation of mechanical properties after water absorption, with a softening coefficient of only about 0.5. Comparative Example 2, lacking the aerogel, has an incomplete hierarchical porous structure, allowing water to easily penetrate. Comparative Example 3, lacking the interfacial bridging effect of polyimide fibers, is prone to structural loosening after water absorption. Both examples have softening coefficients lower than those of the examples, indicating that the aluminum silicate material prepared by this invention has excellent water resistance, greatly expanding its application range and extending its service life.

[0035] In summary, this invention successfully constructs an aluminosilicate insulation material with excellent thermal insulation performance, mechanical properties, and high-temperature stability through the synergistic design of the functional enhancement composite and the aluminosilicate matrix, combined with a precisely controlled preparation process. The functional enhancement composite imparts a multi-level porous structure to the material, enhancing its thermal insulation effect; the fiber component improves the material's brittleness and provides flexible support; and the boehmite sheath layer achieves interfacial bonding and skeletal reinforcement. During the preparation process, the full utilization of the functions of each component and the integrity of the material structure are further ensured, effectively solving problems such as poor aerogel dispersibility and easy structural collapse at high temperatures. While maintaining lightweight characteristics, the material of this invention possesses both excellent thermal insulation capabilities due to its low thermal conductivity and stable mechanical strength and resistance to high-temperature shrinkage. It can be adapted to the application needs of various scenarios such as building exterior walls, industrial furnace linings, and new energy equipment, achieving a systematic improvement in the performance of insulation materials and expanding their application boundaries.

[0036] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An aluminum silicate thermal insulation material, characterized in that, The raw materials include the following parts by weight: 60-80 parts aluminosilicate fiber, 5-15 parts polyvinyl alcohol fiber, 15-25 parts functional reinforcing composite, 8-12 parts silica sol, and 0.1-0.3 parts anionic polyacrylamide. The functional enhancement composite comprises raw materials in the following mass ratio: silicon carbide aerogel powder: polyimide chopped fibers: boehmite sol: silane coupling agent: anionic dispersant = 10-12: 5: 30: 0.2: 0.05; The method for preparing the functionally enhanced complex includes the following steps: (1) Heat-treat silicon carbide aerogel powder to activate it, disperse the activated silicon carbide aerogel in toluene, add silane coupling agent, reflux reaction, filter and wash after the reaction is completed, dry to obtain modified silicon carbide aerogel. (2) Take polyimide short chopped fibers and disperse them in deionized water. Add an anionic dispersant and stir at high speed to form a fiber suspension. Under strong stirring, add modified silicon carbide aerogel to the fiber suspension and continue stirring. Then let it stand and age, and vacuum filter to obtain wet composite felt. (3) The wet composite felt is completely immersed in boehmite sol and impregnated under vacuum conditions. Then it is aged at a constant temperature, dried, crushed, and sieved to obtain the functionally enhanced composite.

2. The aluminum silicate insulation material according to claim 1, characterized in that, In step (1), the ratio of silicon carbide aerogel to toluene is 1g:5mL; In step (2), the ratio of the amount of polyimide short-cut fiber to deionized water is 1g:40mL.

3. The aluminum silicate insulation material according to claim 1, characterized in that, The boehmite sol comprises the following raw materials in the following mass ratio: isopropanol:aluminum isopropoxide = 1:7-8; The preparation process of the boehmite sol is as follows: aluminum isopropoxide is added to isopropanol and mixed, placed in an oil bath, heated and dissolved to obtain a clear solution, deionized water is added dropwise to the clear solution at a constant temperature to carry out a hydrolysis reflux reaction, after the reaction is completed, it is cooled to room temperature to obtain boehmite slurry, dilute nitric acid solution is added dropwise to it, and then it is concentrated and filtered to obtain boehmite sol.

4. A method for preparing an aluminum silicate thermal insulation material according to any one of claims 1-3, characterized in that, Specifically, the following steps are included: S1. Polyvinyl alcohol fiber is added to deionized water, heated and stirred to form a uniform slurry. Heating is stopped, deionized water is added to the slurry, and after cooling, aluminum silicate fiber is added and pulped to form a fiber suspension slurry. S2, the functional enhancement compound is added to the fiber suspension slurry under low-speed shearing, and the mixture is stirred and dispersed to obtain a mixed slurry; S3, the mixed slurry is formed into shape, and anionic polyacrylamide is added during the forming process for flocculation and dehydration to obtain a wet blank; S4, the wet blank is immersed in silica sol for reinforcement, and then dried to obtain a dry blank; S5. The dry blank is subjected to programmed temperature-controlled heat treatment to obtain aluminum silicate insulation material.

5. The method for preparing an aluminum silicate thermal insulation material according to claim 4, characterized in that, In step S5, the process of the programmed temperature rise heat treatment is as follows: First, the temperature is raised from room temperature to 300°C at a rate of 1-2°C / min. Then, the temperature is raised from 300°C to 500-700°C at a rate of 2°C / min to decompose organic matter, and held at this temperature for 1 hour. Next, the temperature is raised from this temperature to 800°C at a rate of 3°C / min, and held at 800°C for 1 hour to activate the inorganic phase. Finally, the temperature is raised from 800°C to 1100-1200°C at a rate of 5°C / min, and held at this temperature for 2 hours to perform mullite sintering. Then, the furnace is cooled to room temperature.

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