CN111908842A - Nano heat-insulating material and preparation method thereof - Google Patents

Nano heat-insulating material and preparation method thereof Download PDF

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Publication number
CN111908842A
CN111908842A CN202010758264.9A CN202010758264A CN111908842A CN 111908842 A CN111908842 A CN 111908842A CN 202010758264 A CN202010758264 A CN 202010758264A CN 111908842 A CN111908842 A CN 111908842A
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mixed
mass
nano
long
gas
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刘晓波
孔德隆
安烜熜
张凡
刘韬
李文静
杨洁颖
张昊
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Aerospace Research Institute of Materials and Processing Technology
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Aerospace Research Institute of Materials and Processing Technology
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    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/76Use at unusual temperatures, e.g. sub-zero
    • C04B2111/763High temperatures
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2201/00Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/20Mortars, concrete or artificial stone characterised by specific physical values for the density
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2201/00Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/30Mortars, concrete or artificial stone characterised by specific physical values for heat transfer properties such as thermal insulation values, e.g. R-values
    • C04B2201/32Mortars, concrete or artificial stone characterised by specific physical values for heat transfer properties such as thermal insulation values, e.g. R-values for the thermal conductivity, e.g. K-factors
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2201/00Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/50Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength

Abstract

The invention provides a nano heat-insulating material and a preparation method thereof. The invention fundamentally solves the dust problem in the mixing and pressing stages by the method of carrying out wet granulation on the powder and then carrying out compression molding, and simultaneously, the components of the granulated raw materials are fixed, so that the problem of raw material sinking caused by high density of individual raw material components is avoided in the transportation and storage processes, thereby solving the problem of uniformity of products.

Description

Nano heat-insulating material and preparation method thereof
Technical Field
The invention relates to a nano heat-insulating material and a preparation method thereof, belonging to the technical field of heat-insulating structural materials.
Background
The heat insulating material is a material capable of retarding heat flow transmission, and is also called a heat protective material, a heat insulating material or a heat insulating material. The heat insulating material is widely applied to the fields of national defense and civil use, particularly the heat insulating material with light weight, high strength and high temperature resistance, and has great requirements in the fields of aerospace, metallurgy, nuclear energy, electric power and the like.
The existing nanometer heat insulating material is prepared by mixing gas phase nanometer silicon dioxide as a main component and adding components such as an anti-radiation agent, short fibers and the like, and then directly pressing, is a heat insulating material with low cost and excellent heat insulating performance, and has the advantages of low production cost, good heat insulating performance, high heat resisting temperature and the like. However, this material also has significant disadvantages: firstly, as the material is formed by dry mixing and dry pressing, and no adhesive is used, the fumed silica with extremely low density can cause extremely large dust in the mixing and pressing processes, and the working environment of workers is seriously influenced; secondly, because the components of the raw materials have density difference, the additive with high density gradually settles at the bottom of the mixture in the processes of storage and transportation of the uniformly mixed materials, so that the uniformity of the raw materials is changed, and the performance of the product is further fluctuated and different. Thirdly, the strength of the nano heat-insulating material obtained by the method is low, and the product has a remarkable powder falling phenomenon.
If the adhesive is added into the material to improve the powder falling phenomenon, under the condition of not influencing the performance, the addition amount of the adhesive cannot be too much, and the adhesive is difficult to disperse if being directly added, and if the adhesive is added with a solvent to prepare thinner glue solution, the problem of raw material sinking caused by high density of individual raw material components in the transportation and storage processes also exists, and the uniformity of the raw materials is changed.
If granulation is adopted, although storage and transportation can be facilitated, and the problem of material layering can be solved, due to the fact that the chopped fibers are contained, the chopped fibers cannot guarantee the length and the natural state in the granulation process, and the effect of adding the chopped fibers in a subsequently obtained product is lost.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a nano heat-insulating material which is environment-friendly, good in uniformity, low in cost, high in strength and high in temperature resistance and a preparation method thereof.
The technical solution of the invention is as follows: a preparation method of a nanometer heat-insulating material is realized by the following steps:
the first step, the preparation of the material,
a1.1, weighing the gas-phase nano-silica, the chopped fiber and the adhesive in proportion, wherein the mass percent of the gas-phase nano-silica is not less than 60%, the mass percent of the adhesive is not more than 15%, the addition amount of the chopped fiber is not more than 50% of the mass of the gas-phase nano-silica, and the sum of the mass percent of the gas-phase nano-silica, the chopped fiber and the adhesive is 100;
a1.2, uniformly mixing the gas-phase nano silicon dioxide and the chopped fibers according to the proportion of the step A1.1 to obtain a mixed dry material, and preparing an adhesive solution from an adhesive and water;
secondly, adding a binder solution into the mixed dry material, and kneading uniformly to obtain a mixed material;
thirdly, granulating the mixed material to obtain long particles, judging the state of the long particles, if the state of the long particles does not meet the requirement, performing the fourth step, and if the state of the long particles meets the requirement, performing the fifth step;
fourthly, adding a proper amount of water or dry mixed materials into the mixed materials, kneading uniformly, and returning to the third step;
fifthly, granulating the mixed material to obtain long granules;
sixthly, weighing a certain quantity of the long granules obtained in the fifth step according to design requirements, and performing compression molding;
and seventhly, performing hydrophobic treatment.
A nanometer heat-insulating material obtained by the preparation method.
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention carries on the wet granulation to the powder first, then the method of the compression molding, have solved the dust problem in compounding, pressing stage fundamentally, meanwhile, the raw materials after granulating are fixed among every component, in transporting, storing, have avoided the sinking problem of raw materials caused by the density of individual raw materials is great, thus has solved the homogeneity problem of the products;
(2) according to the invention, through special granulation and judgment of the state of the granules, high-quality granules are obtained (the granules are not loosened or adhered, and the integrity of fibers in the granules is ensured as much as possible), the strength of the heat-insulating material obtained by pressing and molding is greatly increased, the powder falling phenomenon is obviously improved, and the heat-insulating material has uniform performance, high strength and high heat resistance;
(3) in the compression molding stage, the high-strength high-temperature-resistant nano heat-insulating material with controllable structure, composition and density gradient can be further prepared by controlling the structure, composition and particle size of added particles or pre-arranging fibers, braided fabrics, woven fabrics and non-woven fabrics among the particles;
(4) the preparation process of the invention does not need supercritical drying, high-temperature sintering and other process measures, so that the preparation cost is greatly reduced;
(5) the invention has the advantages of controllable density, high strength, high heat-resisting temperature, good heat-insulating property, good machinability and the like, and the density range is 0.4-1.5g/cm3The compression strength is not lower than 1.5MPa, the room temperature thermal conductivity is not higher than 0.055W/(m.K), and the maximum temperature range of the long-term service is 1000-1200 ℃.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
The present invention will be described in detail with reference to the following examples and accompanying drawings.
The invention provides a preparation method of a nanometer heat-insulating material, as shown in figure 1, and the preparation method is realized by the following steps:
step one, preparing a material,
a1.1, weighing the gas-phase nano-silica, the chopped fiber and the adhesive according to the proportion, wherein the mass percent of the gas-phase nano-silica is not less than 60 percent, the mass percent of the adhesive is not more than 15 percent, the addition amount of the chopped fiber is not more than 50 percent of the mass of the gas-phase nano-silica, and the sum of the mass percent of the gas-phase nano-silica, the chopped fiber and.
In the step, the gas phase nano silicon dioxide is a heat insulation main body material, and can be commercially available without other special limitations if the gas phase nano silicon dioxide has hydrophilicity.
In the step, a small amount of binder is added to serve as a material particle interface bonding carrier, and a water-soluble binder is adopted, preferably an inorganic water-soluble binder, such as one or a combination of silica sol, water glass, and aluminum sol, but not limited thereto, and is selected by those skilled in the art according to specific needs.
The addition amount of the binder in the step is the percentage of the mass of the solid remained in the material after the binder glue solution is dried to the total mass of the material.
The chopped fiber in the step has the functions of reinforcement, heat insulation, filling, mechanical reinforcement, high temperature resistance and the like, and preferably adopts inorganic fibers, the length of the inorganic fibers is 1-15 mm, and no bundling exists among the fibers. The type of the fiber is not particularly limited as long as the properties of the final product are not adversely affected, and one or a combination of more of quartz fiber, high silica glass fiber, mullite fiber, basalt fiber and the like is preferred, but the fiber is not limited thereto, and is selected by those skilled in the art according to specific needs.
Further, the step can also comprise a high-temperature stabilizer, the addition amount of the high-temperature stabilizer is not more than 30% of the mass of the gas-phase nano silicon dioxide, and the high-temperature stabilizer has the functions of filling, strengthening, heat insulation, solid-phase dispersion, anti-melting, delayed phase change and the like, and comprises but is not limited to one or any combination of more of expanded vermiculite, expanded perlite, bentonite, nano montmorillonite and the like.
Further, the step may further include a functional filler, the addition amount of the functional filler is not more than 5% of the mass of the fumed nano-silica, and the functional filler may have functions of reinforcement, heat insulation, filling, radiation resistance, melting resistance, crystal transformation resistance and the like, and includes one or more of nano-alumina, nano-zirconia, nano-titania, nano-silicon carbide, nano-boron carbide and the like in any proportion, but is not limited thereto, and a person skilled in the art selects the functional filler according to specific needs.
Further, the method can also comprise industrial additives, the addition amount of the industrial additives is not more than 1% of the mass of the gas-phase nano silicon dioxide, and the industrial additives have single or multiple effects of antistatic, moisture-proof, anticorrosion, aging resistance, plasticization, ultraviolet resistance, frost resistance, coloring, skinning resistance, dispersion and the like, and are selected by the technical personnel in the field according to specific needs.
In the step, the nano heat-insulating material with different heat-resisting temperatures, different strengths, different heat-insulating properties and different densities can be prepared by adjusting the raw material ratio in the material composition formula. The proportion is adjusted within the range according to specific needs by the person skilled in the art.
A1.2, uniformly mixing the gas-phase nano silicon dioxide and the chopped fibers according to the proportion of the step A1.1 to obtain a mixed dry material, and preparing an adhesive solution from an adhesive and water.
In the step, the adhesive solution is generally prepared from an adhesive glue solution and water, wherein the mass of the adhesive glue solution is equal to the mass of the adhesive/the concentration of the adhesive glue solution.
The mass of the water in the step is 2-5 times, preferably 2-3 times of the total mass of the gas-phase nano silicon dioxide, the chopped fiber and the adhesive.
And further, if the high-temperature stabilizing agent, the functional filler and/or the industrial auxiliary agent are/is contained, the gas-phase nano silicon dioxide, the chopped fiber, the high-temperature stabilizing agent, the functional filler and/or the industrial auxiliary agent are uniformly mixed to obtain a mixed dry material. The mass of the water is 2 to 5 times, preferably 2 to 3 times of the total mass of the gas-phase nano-silica, the chopped fiber, the high-temperature stabilizer, the functional filler and/or the industrial auxiliary agent and the adhesive.
And step two, adding a binder solution into the mixed dry material, and kneading uniformly to obtain a mixed material.
The kneading time in this step is selected on the basis of uniformity, generally not less than 10 minutes, and is selected by those skilled in the art according to actual conditions.
And step three, granulating the mixed material to obtain long particles, judging the state of the long particles, if the state of the long particles does not meet the requirement, performing step four, and if the state of the long particles meets the requirement, performing step five.
The granulation in the step adopts a known extrusion granulation technology, a small amount of materials can be granulated by using existing equipment such as a hand-operated small granulator and a copper screen, the preferred particle size range is 20-60 meshes, a granulation device is modified during granulation, an extruded product is not cut off, and the extruded product is naturally broken under the action of gravity to obtain long particles, so that the integrity of fibers in the particles is ensured as much as possible, and other granulation processes refer to the known technology in the field.
The long particle state judgment standard in the step is that the produced particles naturally break at a length of 5-50 mm, whether the naturally broken long particles are secondarily broken after naturally falling at a height of 10-20 cm is judged, if the secondary breakage is caused, the requirement is judged to be not met, and if the secondary breakage is not caused, the requirement is judged to be met.
According to the invention, special long particles are obtained through granulation, and the preparation process and the formula are finely adjusted through judging the state of the long particles, so that high-quality particles are finally obtained, the obtained particles are not loosened or adhered, the integrity of fibers in the particles is ensured as far as possible, the subsequent compression molding is facilitated, and the heat-insulating material with uniform performance, high strength and high heat resistance is obtained.
And step four, adding a proper amount of water or mixed dry materials into the mixture, kneading uniformly, and returning to the step three.
In this step, if the third granulation cannot be naturally broken at a predetermined length, a proper amount of dry mixed material is added to the mixed material, and if the third granulation can be naturally broken at a predetermined length but naturally falls at a predetermined height and is secondarily broken, a proper amount of water is added to the mixed material.
Further, in this step, for better process control, the addition amount of water or dry mixed materials is preferably not more than 10% of the mass of the water or dry mixed materials in step a1.2, and the specific addition amount is determined by the actual state of the mixed materials.
The kneading time in this step is selected on the basis of uniformity, and is generally not less than 10 minutes. The skilled person will select the choice depending on the actual situation.
And step five, granulating the mixed material to obtain long granules.
The granulation process in the step is consistent with that in the step three, and long granules are obtained by natural fracture under the action of gravity without cutting treatment.
Other steps of the granulation process of the step I and the step II can adopt the known technology in the field, and can also specifically adopt the following process, long granules produced by the granulator are transferred to a blowing oven at 50-90 ℃ to be dried for 1-3 hours, then the temperature is raised to 120-200 ℃ to be dried for 1-3 hours, and the long granules are taken out and cooled to the room temperature.
And step six, weighing the long particles obtained in the step five according to the design requirement, and performing compression molding.
Furthermore, fibers, woven fabrics or non-woven fabrics and the like are preset among the long particles in the step, and the nano heat-insulating material with controllable structure, composition and density gradient is obtained through pressing.
The design of the mould and the design density of the product in the step are known technologies, and the pressing process comprises forming and pressure maintaining pressure, pressure maintaining time, forming temperature and the like, wherein the forming and pressure maintaining pressure is preferably 2-5 MPa and the pressure maintaining time is 10-300 minutes by taking the prior art as reference.
The mass of the long particles is calculated as follows: the mass of the long particles is the mold volume design density. In the step, the density value is designed to be 0.4-1.5g/cm3The range is adjustable.
And step seven, according to requirements, machining, such as turning, punching and other operations can be carried out on the nano heat insulation material obtained in the step six, and the nano heat insulation material added product with the required size and shape is further obtained.
And step eight, performing hydrophobic treatment on the machined product obtained in the step seven.
The hydrophobic treatment in this step can be performed by techniques known in the art, such as placing in a vacuum tank filled with trimethyl methoxy silane vapor for hydrophobic treatment, treating at 70-150 deg.C for 5-30 hr, and taking out to obtain a high-strength high-temperature-resistant nano heat-insulating material.
Further, the invention provides the nano heat-insulating material obtained by the preparation method, and the raw materials are prepared into long particles with controllable particle size through a wet granulation process without cutting, and then the long particles are dried and finally directly pressed and molded through a dry method.
Example 1
The preparation method of the nanometer heat-insulating material comprises the following specific steps:
1. and (5) preparing materials.
A1.1, weighing 60% of hydrophilic gas-phase nano-silica, 15% of adhesive and 25% of chopped fiber according to the mass percentage.
In the embodiment, the adhesive is selected from silica sol with a solid content of 20%, in the step, the adhesive solution is generally prepared from adhesive glue solution and water, and the mass of the adhesive glue solution is equal to the mass of the adhesive/the concentration of the adhesive glue solution. In this example, a quartz fiber having a length of 15mm and no bundling between fiber fibers was selected.
A1.2, uniformly mixing the gas-phase nano silicon dioxide and the chopped fibers according to the proportion of the step A1.1 to obtain a mixed dry material, and preparing an adhesive solution from an adhesive and water.
The mass of the water in the step is 2 times of the total mass of the gas-phase nano silicon dioxide, the chopped fiber and the adhesive.
2. And adding a binder solution into the mixed dry material, and kneading uniformly to obtain a mixed material.
The kneading time in this step was 10 minutes.
3. The mixed material is granulated to obtain long granules, in the embodiment, a hand-operated small granulator is used for granulating a small amount of materials, the particle size is 20 meshes, and a granulating device is modified during granulation, so that an extrudate is not cut off and naturally broken under the action of gravity to obtain long granules, and the integrity of fibers in the granules is ensured as much as possible.
4. Judging the state of the long particles, naturally breaking the produced particles at the length of 8-12 mm, exposing the fibers from the cross section, and breaking the long particles twice after naturally falling at the height of 20 cm, and judging that the long particles are not in accordance with the requirements.
5. And (3) adding 10% of the water in the step (1) into the mixture, kneading for 12 minutes until the mixture is uniform, granulating and dropping in the steps (3) and (4) again, and judging that the long granules are qualified if no secondary fracture exists.
6. And granulating the mixed material meeting the requirements to obtain long granules.
In the step, the granulation process step 3 is consistent, and the long granules are obtained by natural fracture under the action of gravity without cutting treatment.
This step and the granulation process of step 3 the other steps in this example were carried out by transferring the long granules produced by the granulator to a 90 ℃ forced air oven for drying for 1 hour, then heating to 120 ℃ for drying for 3 hours, taking out the long granules, and cooling to room temperature.
7. And (4) weighing a certain mass of the long granules obtained in the step (6) according to design requirements, and performing compression molding. In this example, the dwell pressure was 2MPa and the dwell time was 300 minutes.
The mass of the long particles is calculated as follows: the mass of the long particles is the mold volume design density. In the step, the density value is designed to be 0.4-1.5g/cm3The range is adjustable, in this embodiment, the designed density value is 0.4g/cm3
8. According to the requirement, in this embodiment, the nano heat insulation material obtained in step 7 is subjected to machining of 150 × 20mm, so as to further obtain a nano heat insulation material added product with a desired size and shape.
9. And (4) performing hydrophobic treatment on the machined product obtained in the step (8).
The hydrophobic treatment in this step can be performed by techniques known in the art, and in this example, the material is placed in a vacuum tank filled with trimethyl methoxy silane vapor for hydrophobic treatment, and the material is taken out after treatment at 150 ℃ for 5 hours, so as to obtain the high-strength high-temperature-resistant nano heat-insulating material.
Through tests, the high-strength high-temperature-resistant nano heat-insulating material product obtained in the embodiment is white and has the density of 0.4g/cm3The compression strength is 1.0MPa, the room temperature thermal conductivity is 0.036W/(m.K), and the maximum temperature range of the long-term service is 1000 ℃.
Example 2
The preparation method of the nanometer heat-insulating material comprises the following specific steps:
1. and (5) preparing materials.
A1.1, weighing 60% of hydrophilic gas-phase nano-silica, 15% of adhesive and 25% of chopped fiber according to the mass percentage.
In the embodiment, the adhesive is selected from silica sol with a solid content of 20%, in the step, the adhesive solution is generally prepared from adhesive glue solution and water, and the mass of the adhesive glue solution is equal to the mass of the adhesive/the concentration of the adhesive glue solution. In this example, a quartz fiber having a length of 15mm and no bundling between fiber fibers was selected.
A1.2, uniformly mixing the gas-phase nano silicon dioxide and the chopped fibers according to the proportion of the step A1.1 to obtain a mixed dry material, and preparing an adhesive solution from an adhesive and water.
The mass of the water in the step is 5 times of the total mass of the gas-phase nano silicon dioxide, the chopped fiber and the adhesive.
2. And adding a binder solution into the mixed dry material, and kneading uniformly to obtain a mixed material.
The kneading time in this step was 10 minutes.
3. The mixed material is granulated to obtain long granules, in the embodiment, a hand-operated small granulator is used for granulating a small amount of materials, the particle size is 20 meshes, and a granulating device is modified during granulation, so that an extrudate is not cut off and naturally broken under the action of gravity to obtain long granules, and the integrity of fibers in the granules is ensured as much as possible.
4. Judging the state of the long granules, and judging that the produced granules exceed 50mm, do not break naturally and are not qualified.
5. And (3) adding 10% of the dry mixed material in the step (1) into the mixture, kneading for 15 minutes until the mixture is uniform, performing granulation and falling again in the steps (3) and (4), wherein the produced particles naturally break at 20-24mm, and do not have secondary fracture after naturally falling at a height of 20 cm, and the judgment is that the particles meet the requirements.
6. And granulating the mixed material meeting the requirements to obtain long granules.
In the step, the granulation process step 3 is consistent, and the long granules are obtained by natural fracture under the action of gravity without cutting treatment.
This step and the granulation process of step 3 the other steps in this example were carried out by transferring the long granules produced by the granulator to a 90 ℃ forced air oven for drying for 1 hour, then heating to 120 ℃ for drying for 3 hours, taking out the long granules, and cooling to room temperature.
7. And (4) weighing a certain mass of the long granules obtained in the step (6) according to design requirements, and performing compression molding. In this example, the dwell pressure was 2MPa and the dwell time was 300 minutes.
The mass of the long particles is calculated as follows: the mass of the long particles is the mold volume design density. In the step, the density value is designed to be 0.4-1.5g/cm3The range is adjustable, in this embodiment, the designed density value is 0.4g/cm3
8. According to the requirement, in this embodiment, the nano heat insulation material obtained in step 7 is subjected to machining of 150 × 20mm, so as to further obtain a nano heat insulation material added product with a desired size and shape.
9. And (4) performing hydrophobic treatment on the machined product obtained in the step (8).
The hydrophobic treatment in this step can be performed by techniques known in the art, and in this example, the material is placed in a vacuum tank filled with trimethyl methoxy silane vapor for hydrophobic treatment, and the material is taken out after treatment at 150 ℃ for 5 hours, so as to obtain the high-strength high-temperature-resistant nano heat-insulating material.
Through tests, the high-strength high-temperature-resistant nano heat-insulating material product obtained in the embodiment is white and has the density of 0.4g/cm3The compression strength is 1.05MPa, the room temperature thermal conductivity is 0.038W/(m.K), and the maximum temperature range of the long-term service is 1000 ℃.
Example 3
The preparation method of the nanometer heat-insulating material comprises the following specific steps:
1. and (5) preparing materials.
A1.1, weighing 60% of hydrophilic gas-phase nano-silica, 15% of adhesive and 25% of chopped fiber according to the mass percentage.
Silica sol with a solid content of 10% was selected in this example. The chopped fiber is high silica glass fiber with length of 1mm and no bundling between fibers.
The embodiment also comprises a high-temperature stabilizer, the addition amount of the high-temperature stabilizer is 30% of the mass of the gas-phase nano silicon dioxide, and the mass ratio of the expanded vermiculite to the nano montmorillonite is 1: 1.
The embodiment also comprises a functional filler, the addition amount of the functional filler is 5% of the mass of the gas-phase nano silicon dioxide, and the mass ratio of the nano silicon carbide to the nano titanium dioxide is 1: 1.
A1.2, uniformly mixing the gas-phase nano-silica, the chopped fibers, the high-temperature stabilizer and the functional filler according to the proportion of the step A1.1 to obtain a mixed dry material, and preparing an adhesive solution from an adhesive and water.
In the step, the adhesive solution is prepared from adhesive glue solution and water, and the quality of the adhesive glue solution is equal to the mass of the adhesive/the concentration of the adhesive glue solution.
The mass of the water in the step is 3 times of the total mass of the gas-phase nano-silica, the chopped fiber, the high-temperature stabilizer, the functional filler and the adhesive.
2. And adding a binder solution into the mixed dry material, and kneading uniformly to obtain a mixed material.
In this example, the actual kneading time was 15 minutes.
3. Granulating the mixed material to obtain long granules, granulating a small amount of material by using a hand-operated small granulator, preferably, the particle size range is 60 meshes, and modifying a granulating device during granulation to ensure that the extrudate is not cut off and naturally broken under the action of gravity to obtain the long granules so as to ensure the integrity of fibers in the granules as far as possible.
4. And judging the state of the long particles, wherein the produced particles naturally break within the length range of 5-10 mm, the naturally broken long particles naturally break for a second time after falling down at a height of 15 cm, and the state of the long particles does not meet the requirement.
5. And (3) adding 10% of the water in the step (1) into the mixture, kneading for 15 minutes until the mixture is uniform, granulating and dropping in the steps (3) and (4) again, and judging that the long granules are qualified if no secondary fracture exists.
6. And granulating the mixed material to obtain long granules.
In the step, the granulation process step 3 is consistent, and the long granules are obtained by natural fracture under the action of gravity without cutting treatment.
This step and the other steps of the granulation process of step 3 can adopt the technology known in the art, and the following process is adopted in the embodiment, after the long granules produced by the granulator are transferred to a 60 ℃ air blast oven for drying for 3 hours, the temperature is increased to 200 ℃ for drying for 1 hour, and the long granules are taken out and cooled to the room temperature.
7. And (4) weighing a certain mass of the long granules obtained in the step (6) according to design requirements, and performing compression molding.
In the step, a three-dimensional braided fabric is preset among the long particles, and the nano heat-insulating material with controllable structure, composition and density gradient is obtained by pressing.
The design of the molding die and the design density of the product in this step are known technologies, and in this embodiment, the molding and pressure holding pressure is 5MPa, and the pressure holding time is 30 minutes.
The mass of the long particles is calculated as follows: the mass of the long particles is the mold volume design density. The density value designed in the step is 1.5g/cm3
8. And (4) according to requirements, carrying out mechanical processing on the nano heat insulation material obtained in the step (7), such as turning, punching and other operations, and further obtaining a nano heat insulation material added product with the required size and shape.
9. And (4) performing hydrophobic treatment on the machined product obtained in the step (8).
The hydrophobic treatment in this step can be performed by techniques known in the art, and in this example, the material is placed in a vacuum tank filled with trimethyl methoxy silane vapor for hydrophobic treatment, and the material is taken out after treatment at 120 ℃ for 20 hours, so as to obtain the high-strength high-temperature-resistant nano heat-insulating material.
Through tests, the high-strength high-temperature-resistant nano heat-insulating material product obtained in the embodiment is white and has the density of 1.5g/cm3The compression strength is 1.8MPa, the room temperature thermal conductivity is 0.045W/(m.K), and the maximum temperature range of the long-term service is 1200 ℃.
Example 4
The preparation method of the nanometer heat-insulating material comprises the following specific steps:
1. and (5) preparing materials.
A1.1, weighing 60% of hydrophilic gas-phase nano-silica, 15% of adhesive and 25% of chopped fiber according to the mass percentage.
In this example, an alumina sol having a solid content of 5% was selected. In this embodiment, the quartz fibers are selected to have a length of 5-10 mm and no bundling between the fibers.
The embodiment also comprises a high-temperature stabilizer, the addition amount of the high-temperature stabilizer is 10% of the mass of the gas-phase nano silicon dioxide, and the nano montmorillonite is selected.
The embodiment also comprises a functional filler, the addition amount of the functional filler is 3% of the mass of the gas-phase nano-silica, and the mass ratio of the nano-zirconia to the nano-titania to the nano-silicon carbide is 1:1: 1.
The embodiment also comprises an industrial additive, wherein the addition amount of the industrial additive is 1% of the mass of the gas-phase nano silicon dioxide, and the industrial additive with antistatic and moisture-proof effects is selected.
A1.2, uniformly mixing the gas-phase nano-silica, the chopped fibers, the high-temperature stabilizer, the functional filler and the industrial auxiliary agent according to the proportion of the step A1.1 to obtain a mixed dry material, and preparing an adhesive solution from the adhesive and water.
The mass of the water in the step is 5 times of the total mass of the gas-phase nano-silica, the chopped fiber, the high-temperature stabilizer, the functional filler, the industrial auxiliary agent and the adhesive.
2. And adding a binder solution into the mixed dry material, and kneading uniformly to obtain a mixed material.
The actual kneading time in this example was 20 minutes.
3. Granulating the mixed material to obtain long granules, granulating a small amount of material by using a hand-operated small granulator, preferably, the particle size range is 20 meshes, modifying a granulating device during granulation to ensure that the extrudate is not cut off and naturally breaks under the action of gravity to obtain long granules so as to ensure the integrity of fibers in the granules as far as possible, and using other granulating processes for reference by the known technology in the field.
4. And judging the state of the long particles, wherein the produced particles naturally break within the length range of 12-15 mm, the naturally broken long particles naturally break for a second time after falling down at a height of 10 cm, and the state of the long particles does not meet the requirement.
5. And (3) adding 10% of the water in the step (1) into the mixture, kneading for 20 minutes until the mixture is uniform, granulating and dropping in the steps (3) and (4) again, and judging that the long granules are qualified if no secondary fracture exists.
6. And granulating the mixed material to obtain long granules.
In the step, the granulation process step 3 is consistent, and the long granules are obtained by natural fracture under the action of gravity without cutting treatment.
The present step and other steps of the granulation process in step 3 may adopt techniques known in the art, and in this example, the following process is specifically adopted, after the long granules produced by the granulator are transferred to a vacuum oven at 90 ℃ for drying for 10 hours, the long granules are taken out and cooled to room temperature.
7. And (3) weighing a certain mass of the long particles obtained in the step (6) according to design requirements, and pressing to obtain the nano heat-insulating material with controllable structure, composition and density gradient.
The design of the molding die and the design density of the product in this step are known technologies, and in this example, the molding and pressure holding pressure is 3MPa, and the pressure holding time is 30 minutes.
The mass of the long particles is calculated as follows: the mass of the long particles is the mold volume design density. The density value designed in the step is 0.7g/cm3
8. And (4) machining the nano heat insulation material obtained in the step (7) according to requirements, and further obtaining a nano heat insulation material added product with the required size and shape.
9. And (4) performing hydrophobic treatment on the machined product obtained in the step (8).
In this embodiment, the nano heat insulating material is placed in a vacuum tank filled with trimethyl methoxy silane vapor for hydrophobic treatment, and is taken out after being treated at 120 ℃ for 24 hours, so as to obtain the high-strength high-temperature-resistant nano heat insulating material.
Tests prove that the high-strength high-temperature-resistant nano heat insulation material obtained in the embodimentThe material product is white, and has the advantages of controllable density, high strength, high heat-resisting temperature, good heat-insulating property, good machinability and the like, and the density is 0.7g/cm3The compression strength is 2.85MPa, the room temperature thermal conductivity is 0.043W/(m.K), and the maximum temperature range of the long-term service is 1050 ℃.
Example 5
The preparation method of the nanometer heat-insulating material comprises the following specific steps:
1. and (5) preparing materials.
A1.1, weighing 80% of hydrophilic gas-phase nano-silica, 5% of adhesive and 15% of chopped fiber according to the mass percentage.
In this example, an alumina phosphate gel having a solid content of 10% was selected. In the embodiment, alumina fibers with the length of 2mm are selected, and no bundling exists among the fibers. The embodiment also comprises a high-temperature stabilizer, the addition amount of the high-temperature stabilizer is 10% of the mass of the gas-phase nano silicon dioxide, and expanded vermiculite powder is selected.
The embodiment also comprises a functional filler, wherein the addition amount of the functional filler is 5% of the mass of the gas-phase nano silicon dioxide, and the functional filler is the combination of nano titanium oxide, micron silicon carbide and micron zirconium silicate in a mass ratio of 1:1: 1.
The embodiment also comprises an industrial additive, wherein the addition amount of the industrial additive is 0.5 percent of the mass of the gas-phase nano silicon dioxide, and the industrial additive with the antistatic effect is selected.
A1.2, uniformly mixing the gas-phase nano-silica, the chopped fibers, the high-temperature stabilizer, the functional filler and the industrial auxiliary agent according to the proportion of the step A1.1 to obtain a mixed dry material, and preparing an adhesive solution from the adhesive and water.
In the step, the adhesive solution is prepared from adhesive glue solution and water, and the quality of the adhesive glue solution is equal to the mass of the adhesive/the concentration of the adhesive glue solution.
The mass of the water in the step is 5 times of the total mass of the gas-phase nano-silica, the chopped fiber, the high-temperature stabilizer, the functional filler, the industrial auxiliary agent and the adhesive.
2. And adding a binder solution into the mixed dry material, and kneading uniformly to obtain a mixed material.
The kneading time in this example was 30 minutes.
3. And (3) granulating the mixed material to obtain long granules, extruding and granulating a small amount of material by using a common copper sieve, preferably selecting the particle size range to be 20 meshes, and naturally breaking under the action of gravity to obtain the long granules so as to ensure the integrity of fibers in the granules as far as possible.
4. And judging the state of the long particles, wherein the produced particles naturally break within the length range of 8-12 mm, the naturally broken long particles naturally break for a second time after falling down at a height of 10 cm, and the state of the long particles does not meet the requirement.
5. And (3) adding 10% of the water in the step (1) into the mixture, kneading for 30 minutes until the mixture is uniform, granulating and dropping in the steps (3) and (4) again, and judging that the long granules are qualified if no secondary fracture exists.
6. And granulating the mixed material to obtain long granules.
The granulation process in the step is consistent with that in the step 3, and specifically adopts the following process, the produced long granules are transferred to a ventilated place for natural drying for 24 hours, then transferred to a blast drying oven for drying for 8 hours at 120 ℃, and then taken out and cooled to room temperature.
7. And (4) weighing a certain mass of the long granules obtained in the step (5) according to design requirements, and performing compression molding.
The design of the mould and the design density of the product in the step are known technologies, the forming and pressure maintaining pressure is 5MPa, and the pressure maintaining time is 300 minutes.
The mass of the long particles is calculated as follows: the mass of the long particles is the mold volume design density. The density value designed in the step is 1.0g/cm3
8. According to the requirement, the nano heat insulation material obtained in the step 7 can be subjected to mechanical processing, such as turning, punching and other operations, so as to further obtain a nano heat insulation material added product with the required size and shape.
9. And (4) performing hydrophobic treatment on the machined product obtained in the step (8).
The hydrophobic treatment in the step adopts the technology known in the art, the hydrophobic treatment is carried out in a vacuum tank filled with trimethyl methoxy silane steam, the hydrophobic treatment is carried out for 20 hours at the temperature of 80 ℃, and then the hydrophobic treatment is taken out, thus obtaining the high-strength high-temperature-resistant nano heat-insulating material.
Tests prove that the high-strength high-temperature-resistant nano heat-insulating material product obtained by the embodiment is white, has the advantages of controllable density, high strength, high heat-resistant temperature, good heat-insulating property, good machinability and the like, and has the density of 1.0g/cm3, the compression strength of 3.28MPa, the room-temperature heat conductivity of 0.056W/(m.K), and the maximum temperature range of 1200 ℃ for long-term service.
The invention has not been described in detail and is in part known to those of skill in the art.

Claims (10)

1. The preparation method of the nanometer heat-insulating material is characterized by comprising the following steps of:
the first step, the preparation of the material,
a1.1, weighing the gas-phase nano-silica, the chopped fiber and the adhesive in proportion, wherein the mass percent of the gas-phase nano-silica is not less than 60%, the mass percent of the adhesive is not more than 15%, the addition amount of the chopped fiber is not more than 50% of the mass of the gas-phase nano-silica, and the sum of the mass percent of the gas-phase nano-silica, the chopped fiber and the adhesive is 100;
a1.2, uniformly mixing the gas-phase nano silicon dioxide and the chopped fibers according to the proportion of the step A1.1 to obtain a mixed dry material, and preparing an adhesive solution from an adhesive and water;
secondly, adding a binder solution into the mixed dry material, and kneading uniformly to obtain a mixed material;
thirdly, granulating the mixed material to obtain long particles, judging the state of the long particles, if the state of the long particles does not meet the requirement, performing the fourth step, and if the state of the long particles meets the requirement, performing the fifth step;
fourthly, adding a proper amount of water or dry mixed materials into the mixed materials, kneading uniformly, and returning to the third step;
fifthly, granulating the mixed material to obtain long granules;
sixthly, weighing a certain quantity of the long granules obtained in the fifth step according to design requirements, and performing compression molding;
and seventhly, performing hydrophobic treatment.
2. The method for preparing a nano heat insulating material according to claim 1, wherein the method comprises the following steps: the step A1.1 also comprises a high-temperature stabilizer, a functional filler and/or an industrial additive, the addition amount of the high-temperature stabilizer is not more than 30% of the mass of the gas-phase nano-silica, the addition amount of the functional filler is not more than 5% of the mass of the gas-phase nano-silica, the addition amount of the industrial additive is not more than 1% of the mass of the gas-phase nano-silica, and the dry material mixed in the step A1.2 also comprises the high-temperature stabilizer, the functional filler and/or the industrial additive.
3. The method for preparing a nano heat insulating material according to claim 1 or 2, wherein: the mass of the water in the step A1.2 is 2-5 times of the total mass of the solid parts, and the solid parts comprise mixed dry materials and adhesives.
4. The method for preparing a nano heat insulating material according to claim 3, wherein the method comprises the following steps: the mass of the water in the step A1.2 is 2-3 times of the total mass of the solid parts.
5. The method for preparing a nano heat insulating material according to claim 1 or 2, wherein: and the long particle state judgment standard in the third step is that the manufactured particles naturally break at the length of 5-50 mm, whether the naturally broken long particles are secondarily broken after naturally falling at the height of 10-20 cm is judged, if the naturally broken long particles are secondarily broken, the requirement is judged to be not met, and if the naturally broken long particles are not secondarily broken, the requirement is judged to be met.
6. The method for preparing a nano heat insulating material according to claim 1 or 2, wherein: in the fourth step, if the third granulation cannot be naturally broken at a predetermined length, a proper amount of dry mixed material is added to the mixed material, and if the third granulation can be naturally broken at a predetermined length but naturally falls and is broken twice at a predetermined height, a proper amount of water is added to the mixed material.
7. The method for preparing a nano heat insulating material according to claim 6, wherein the method comprises the following steps: in the fourth step, the adding amount of the water or the mixed dry material is not more than 10% of the mass of the water or the mixed dry material in the step A1.2.
8. The method for preparing a nano heat insulating material according to claim 1 or 2, wherein: in the third and fifth granulation steps, the extrudate is not cut and naturally broken under the action of gravity.
9. The method for preparing a nano heat insulating material according to claim 1 or 2, wherein: in the sixth step of press forming, fibers, woven fabrics or nonwoven fabrics are preset among the long particles.
10. A nano heat-insulating material obtained by adopting any one of the preparation methods.
CN202010758264.9A 2020-07-31 2020-07-31 Nano heat-insulating material and preparation method thereof Pending CN111908842A (en)

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