Radiation-inhibiting aerogel material and preparation method thereof
By adding reflective radiation inhibitors to SiO2 aerogel, the infrared transmittance is reduced, and the problem of excessive radiant heat transfer at high temperatures is solved, and better high-temperature thermal insulation performance is achieved.
Patent Information
- Application Number
- CN202411829921.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-12
- Publication Date
- 2025-03-21
AI Technical Summary
SiO2 aerogel material has excessive radiant heat transfer at high temperatures, resulting in a degradation of its thermal insulation performance.
By adding reflective radiation inhibitors, the infrared transmittance of the aerogel is reduced, the radiant thermal conductivity is reduced, and the thermal insulation performance is improved. Specific methods include modifying silica aerogels using high reflectivity powders (such as metal oxides or highly reflective metals) and preparing them by supercritical drying and other processes.
It significantly improves the thermal insulation performance of aerogel at high temperatures, reduces the radiant thermal conductivity, and enhances the radiation resistance.
Smart Images
Figure CN119660752A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a radiation suppressing aerogel material and a preparation method thereof, in particular to a doped and modified SiO2 aerogel, belonging to the field of new materials. Background Art
[0002] SiO2 aerogel is a nanoporous material with excellent thermal insulation properties, especially in high-temperature environments. Its low density, high porosity and ultra-low thermal conductivity enable it to effectively isolate heat transfer under extreme temperature conditions. In high-temperature applications, aerogel is often used in thermal protection systems in the aerospace field, such as spacecraft insulation tiles and heat shields to withstand temperatures of thousands of degrees Celsius; in the industrial field, it is widely used in the insulation layer of high-temperature pipes, boilers, kilns and other equipment, greatly reducing heat loss and improving energy utilization; in addition, aerogel can also be used as a carrier for high-temperature catalysts and high-temperature sealing materials, showing great potential in the chemical and energy fields. Its high temperature resistance makes it an ideal high-efficiency thermal insulation and energy-saving material, suitable for a variety of extreme working conditions.
[0003] However, due to the structural characteristics of the SiO2 aerogel material itself, its radiation transmittance is relatively high, resulting in its poor ability to block radiation heat transfer. Radiation heat transfer increases to the fourth power with increasing temperature. Therefore, radiation heat transfer is very serious at high temperatures. The high infrared radiation transmittance effect of aerogel causes its thermal insulation performance at high temperatures to decrease. Summary of the invention
[0004] The purpose of the present invention is to solve the problem of excessively high heat transfer of high-temperature radiation of silica aerogel, and to provide a radiation-suppressing aerogel material and a preparation method thereof. The present invention reduces the infrared transmittance of aerogel and the radiation thermal conductivity of aerogel material by adding a reflective radiation inhibitor, thereby improving the thermal insulation performance of aerogel material at high temperature.
[0005] The present invention is achieved through the following technical solutions.
[0006] A radiation suppressing aerogel material is a high-reflectivity powder-modified silica aerogel, wherein the high-reflectivity powder is a metal oxide or a high-reflectivity metal.
[0007] Furthermore, the density of the radiation-suppressing aerogel material is 250-350 kg / m 3 .
[0008] Furthermore, the mass fraction of high reflectivity powder in the radiation suppression aerogel material is 2-5%, and the high reflectivity powder is metal oxide or high reflectivity metal (TiO2, ZrO2, Al, Ti, etc.).
[0009] Furthermore, the silicon source of the radiation suppressing aerogel material is alkaline nano-silica sol.
[0010] Furthermore, the radiation suppressing aerogel material is prepared by a supercritical drying method.
[0011] Furthermore, the back temperature of the radiation-suppressing aerogel material is more than 50° C. lower than that of conventional silica aerogel when subjected to single-sided thermal testing at 800° C. for 3600 s.
[0012] A method for preparing a radiation-suppressing aerogel material, the steps of the method are as follows:
[0013] (1) Plasma modification of high reflectivity powder;
[0014] (2) adding the modified high reflectivity powder into an alkaline nano-silica sol solution to obtain a suspension;
[0015] (3) adding a surfactant to the suspension and stirring to obtain a mixed glue solution;
[0016] (4) adding acid to the mixed gel solution and allowing it to stand for a certain period of time to obtain a hydrogel;
[0017] (5) heating the hydrogel;
[0018] (6) performing solvent replacement on the hydrogel after the heating treatment;
[0019] (7) The replaced hydrogel is subjected to supercritical drying to obtain a radiation-suppressing aerogel material.
[0020] Furthermore, in step (1), a high reflectivity powder (TiO2, ZrO2, Al, Ti, etc.) with a particle size of 10 to 50 nm is selected and plasma modified, wherein the plasma is Ar and the modification time is 4 to 6 minutes. Plasma treatment can remove organic groups on the surface of the high reflectivity powder and further improve its reflectivity in the near-infrared and mid-infrared bands.
[0021] Furthermore, in step (2), the modified high reflectivity powder is added to an alkaline nano-silica sol solution with a solid content of 20 to 25% at a mass fraction of 2 to 5% to obtain a suspension. The alkaline nano-silica sol can be an existing commercially available silica sol, which has a mesh structure and a more excellent aerogel structure after gelation. In addition, the alkaline silica sol is neutralized and gelled with a strong acid without the introduction of metal cations, while the acidic silica sol is usually neutralized and gelled with a strong base, which often introduces metal cations and causes the temperature resistance of the gel to decrease.
[0022] Furthermore, in step (3), the mass of the surfactant added to the suspension accounts for 0.5-1% of the mass of the high reflectivity powder, and the suspension is placed on a magnetic stirrer and stirred at a speed of 150-250 rpm for 10-15 minutes to obtain a mixed glue solution.
[0023] Furthermore, the surfactant is a non-ionic surfactant, which helps to evenly disperse the high reflectivity powder in the aqueous solvent after being added. The surfactant is preferably polyvinyl pyrrolidone (PVP), and triethanolamine, polyethylene glycol, hydroxyethyl cellulose, etc. can also be used.
[0024] Furthermore, in step (4), an acid (HCl, HNO3, H2SO4) is continuously added to the mixed gel solution by dripping, and the pH of the gel solution is judged by pH test paper or pH indicator until the pH is 6.5 to 7.5, then the dripping is stopped and the mixture is allowed to stand for 24 to 48 hours to obtain a hydrogel.
[0025] Furthermore, in step (5), the hydrogel is placed in a constant temperature oven at 60 to 80° C. and heated for 48 to 72 hours.
[0026] Furthermore, in step (6), the hydrogel after the heat treatment is placed in an organic solution such as ethanol, methane or n-hexane for solvent replacement. The replacement time is 7 to 10 days, and the volume of the organic solution during the replacement is 15 to 25 times the volume of the hydrogel.
[0027] Furthermore, in step (7), the replaced hydrogel is subjected to supercritical drying, the drying solvent is CO2, and the drying pressure is 5 to 10 MPa.
[0028] The beneficial effects of the present invention are as follows:
[0029] 1) The present invention adds a reflective radiation inhibitor, which can effectively improve the radiation resistance of the aerogel and reduce its radiation thermal conductivity at high temperatures, so that it can obtain better high-temperature thermal insulation performance.
[0030] 2) The radiation-resistant aerogel prepared by the present invention adopts a supercritical drying scheme, and the obtained aerogel has small internal nanoparticle size, high porosity and good stability.
[0031] 3) The aerogel prepared by the present invention is prepared by aqueous solvent, which avoids the cumbersome process caused by using orthosilicate hydrolysis gel, and does not produce high-waste brine. The process is simple and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Figure 1 The organizational structure of the radiation suppression aerogel material prepared in Example 1;
[0033] Figure 2 The organizational structure of the radiation suppression aerogel material prepared in Example 2;
[0034] Figure 3 This is the organizational structure of the radiation suppressing aerogel material prepared in Example 3. Specific implementation methods
[0036] The present invention is further described in detail below by examples.
[0037] Example 1
[0038] A preparation process of a radiation-suppressing aerogel material, the method steps are as follows:
[0039] (1) Select TiO2 powder material with a particle size of 10 nm and perform plasma modification on it. The plasma is Ar and the modification time is 4 minutes.
[0040] (2) The modified high reflectivity powder material is added into an alkaline nano-silica sol solution with a solid content of 20% at a mass fraction to obtain a suspension.
[0041] (3) Add polyvinyl pyrrolidone (PVP) in a ratio of 0.5% of the mass of the high reflectivity powder material to the suspension, and place it on a magnetic stirrer and stir it at a speed of 150 rpm for 10 minutes to obtain a mixed glue solution.
[0042] (4) HCl is continuously added dropwise to the mixed gel solution, and the pH of the gel solution is determined by pH test paper or a pH indicator until the pH reaches 6.5, then the addition is stopped and the mixture is allowed to stand for 24 hours to obtain a hydrogel.
[0043] (5) The hydrogel was placed in a constant temperature oven at 60°C and heated for 48 h.
[0044] (6) The heated hydrogel was placed in ethanol for solvent replacement for 7 days. The volume of the organic solution during the replacement was 15 times the volume of the hydrogel.
[0045] (7) The replaced hydrogel is subjected to supercritical drying, the drying solvent is CO2, and the drying pressure is 5 MPa.
[0046] The organizational structure of the radiation-suppressing aerogel material prepared in this embodiment is as follows: Figure 1 As shown in the figure, the aerogel material has a back temperature 53°C lower than that of traditional silica aerogel when subjected to a single-sided thermal test at 800°C for 3600s.
[0047] Example 2
[0048] A preparation process of a radiation-suppressing aerogel material, the method steps are as follows:
[0049] (1) Select ZrO2 powder material with a particle size of 50 nm and perform plasma modification on it. The plasma is Ar and the modification time is 6 minutes.
[0050] (2) The modified high reflectivity powder material is added into an alkaline nano-silica sol solution with a solid content of 25% at a mass fraction of 5% to obtain a suspension.
[0051] (3) Add polyvinyl pyrrolidone (PVP) in a ratio of 1% of the mass of the high reflectivity powder material to the suspension, and place it on a magnetic stirrer and stir it at a speed of 250 rpm for 15 minutes to obtain a mixed glue solution.
[0052] (4) HNO3 is continuously added dropwise to the mixed gel solution, and the pH of the gel solution is determined by pH test paper or a pH indicator until the pH reaches 7.5, then the addition is stopped and the mixture is allowed to stand for 48 hours to obtain a hydrogel.
[0053] (5) The hydrogel was placed in a constant temperature oven at 80°C and heated for 72 h.
[0054] (6) The heated hydrogel was placed in methane for solvent replacement for 10 days. The volume of the organic solution during the replacement was 25 times the volume of the hydrogel.
[0055] (7) The replaced hydrogel is subjected to supercritical drying, the drying solvent is CO2, and the drying pressure is 10 MPa.
[0056] The organizational structure of the radiation-suppressing aerogel material prepared in this embodiment is as follows: Figure 2 As shown in the figure, the aerogel material has a back temperature 59°C lower than that of traditional silica aerogel when subjected to a single-sided thermal test at 800°C for 3600s.
[0057] Example 3
[0058] A preparation process of a radiation-suppressing aerogel material, the method steps are as follows:
[0059] (1) A Ti powder material with a particle size of 30 nm was selected and plasma modified. The plasma was Ar and the modification time was 5 min.
[0060] (2) The modified high reflectivity powder material is added into an alkaline nano-silica sol solution with a solid content of 22% at a mass fraction of 3% to obtain a suspension.
[0061] (3) Add polyvinyl pyrrolidone (PVP) in a ratio of 0.7% of the mass of the high reflectivity powder material to the suspension, and place it on a magnetic stirrer and stir it at a speed of 200 rpm for 12 minutes to obtain a mixed glue solution.
[0062] (4) H2SO4 is continuously added dropwise to the mixed gel solution, and the pH of the gel solution is determined by pH test paper or a pH indicator until the pH reaches 7, then the addition is stopped and the mixture is allowed to stand for 36 hours to obtain a hydrogel.
[0063] (5) The hydrogel was placed in a constant temperature oven at 70°C and heated for 60 h.
[0064] (6) The heated hydrogel was placed in n-hexane for solvent replacement. The replacement time was 9 days, and the volume of the organic solution during the replacement was 20 times the volume of the hydrogel.
[0065] (7) The replaced hydrogel is subjected to supercritical drying, the drying solvent is CO2, and the drying pressure is 8 MPa.
[0066] The organizational structure of the radiation-suppressing aerogel material prepared in this embodiment is as follows: Figure 3 As shown in the figure, the aerogel material has a back temperature 62°C lower than that of traditional silica aerogel when subjected to a single-sided thermal test at 800°C for 3600s.
[0067] The specific description above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A radiation-suppressing aerogel material, characterized in that: The radiation suppression aerogel material is a high reflectivity powder-modified silica aerogel, and the high reflectivity powder is a metal oxide or a high reflectivity metal.
2. The radiation suppressant aerogel material according to claim 1, characterized in that: The mass fraction of high reflectivity powder in the radiation suppression aerogel material is 2-5%; the high reflectivity powder is at least one of TiO2, ZrO2, Al and Ti; the silicon source of the radiation suppression aerogel material is alkaline nano-silica sol.
3. The radiation suppressant aerogel material according to claim 1, characterized in that: The density of the radiation-suppressing aerogel material is 250-350 kg / m 3 The back temperature of the radiation-suppressing aerogel material is more than 50°C lower than that of traditional silica aerogel when subjected to single-sided thermal testing at 800°C for 3600s.
4. A method for preparing a radiation-suppressing aerogel material, characterized in that: The following steps are involved: (1) Plasma modification of high reflectivity powder; (2) adding the modified high reflectivity powder into an alkaline nano-silica sol solution to obtain a suspension; (3) adding a surfactant to the suspension and stirring to obtain a mixed glue solution; (4) adding acid to the mixed gel solution and allowing it to stand for a certain period of time to obtain a hydrogel; (5) heating the hydrogel; (6) performing solvent replacement on the hydrogel after the heating treatment; (7) The replaced hydrogel is subjected to supercritical drying to obtain a radiation-suppressing aerogel material.
5. The method according to claim 4, characterized in that Step (1) selects high reflectivity powder with a particle size of 10 to 50 nm for plasma modification, the plasma is selected as Ar, and the modification time is 4 to 6 minutes.
6. The method according to claim 4, characterized in that Step (2) adding the modified high reflectivity powder into an alkaline nano-silica sol solution with a solid content of 20 to 25% at a mass fraction of 2 to 5% to obtain a suspension.
7. The method according to claim 4, characterized in that In step (3), the mass of the surfactant added to the suspension accounts for 0.5-1% of the mass of the high reflectivity powder, and the suspension is placed on a magnetic stirrer and stirred at a speed of 150-250 rpm for 10-15 minutes to obtain a mixed glue solution; the surfactant is one of polyvinyl pyrrolidone, triethanolamine, polyethylene glycol, and hydroxyethyl cellulose.
8. The method according to claim 4, characterized in that Step (4) adding acid to the mixed gel solution in a continuous dripping manner, and judging the pH of the gel solution by pH test paper or pH indicator until the pH is 6.5 to 7.5, then stopping the dripping and standing for 24 to 48 hours to obtain a hydrogel.
9. The method according to claim 4, characterized in that Step (5) placing the hydrogel in a constant temperature oven at 60 to 80° C. and heating it for 48 to 72 hours; Step (6) placing the heated hydrogel in ethanol, methane or n-hexane for solvent replacement, the replacement time is 7 to 10 days, and the volume of the organic solution during the replacement is 15 to 25 times the volume of the hydrogel.
10. The method according to claim 4, characterized in that The drying solvent of the supercritical drying in step (7) is CO2, and the drying pressure is 5 to 10 MPa.