Light / heat insulation / high emission integrated composite material and preparation method thereof

Abstract

The invention relates to a light / heat-insulation / high-emission integrated composite material and a preparation method thereof, and the method comprises the following steps: preparing an aerogel prepolymer from zirconium-hybridized boron phenolic resin, compounding a chromium-aluminum phosphate base solution and a characteristic filler to prepare a composite solution, injecting the chromium-aluminum phosphate / characteristic filler composite solution into a mold filled with the aerogel prepolymer, and molding to obtain the light / heat-insulation / high-emission integrated composite material. The light / heat insulation / high emission integrated composite material is prepared in a co-curing mode. The chromium-aluminum phosphate surface layer of the light / heat-insulation / high-emission integrated composite material prepared by the invention has high emissivity (emissivity epsilon in a range of 3-18 microns is greater than 0.93), heat can be quickly dissipated to the surrounding environment in an infrared radiation manner, and the surface temperature can be effectively reduced; meanwhile, the aerogel inner layer prepared by the experiment has relatively low thermal conductivity, so that heat transfer to the inside can be effectively reduced, and internal devices are protected from being eroded by the heat.

Description

Technical Field

[0001] The present invention belongs to the field of materials, and particularly relates to a lightweight / heat-insulating / high-emissivity integrated composite material and a preparation method thereof. Background Art

[0002] The development of high-speed aircraft is an important direction of modern aerospace technology. It can complete long-distance flight missions in a very short time and has important strategic and tactical values. When an aircraft flies at a high Mach number, the friction between the surface layer and atmospheric molecules will generate a large amount of heat, resulting in a significant increase in the surface temperature of the aircraft. This phenomenon is called aerodynamic heating. Aerodynamic heating will lead to a decline in material performance and even damage. Traditional heat-insulating materials often face problems of heat conduction and radiative heat loss in high-temperature environments. In high-temperature environments, the thermal conductivity of traditional materials may be relatively high, resulting in an increase in heat loss. In addition, the radiative emissivity of traditional materials is not high, resulting in the inability to effectively dissipate heat energy through radiation, making it difficult to control the system temperature. Moreover, the stability and durability of existing high-emissivity coatings at long-term high temperatures are often limited. These factors restrict the realization of effective thermal management and energy efficiency in high-temperature environments. Summary of the Invention

[0003] In view of the above problems in the background art, the present invention provides a lightweight / heat-insulating / high-emissivity integrated composite material and a preparation method thereof. The prepared material has excellent radiative heat dissipation ability and heat-insulating effect to protect the internal structure of the device from high-temperature damage.

[0004] Phenolic aerogel has an extremely low thermal conductivity, excellent thermal resistance value, lightweight, high-temperature resistance and chemical stability, and is an ideal heat-insulating material. The zirconium hybrid boron phenolic aerogel of the present invention improves the heat resistance of ordinary phenolic aerogel, enabling it to adapt to higher temperatures; the high-emissivity surface layer of the present invention has a high emissivity and excellent thermal stability, which helps to continuously radiate the heat generated during flight into space and protect the aircraft from high-temperature damage. The composite material of the present invention can not only reduce heat conduction loss, but also enhance the radiative heat dissipation effect of heat energy by increasing the radiative emissivity, thereby effectively reducing the surface temperature of the system and is applicable to fields such as energy, aerospace, etc.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A preparation method of a lightweight / heat-insulating / high-emissivity integrated composite material, the method being:

[0007] Step 1: Weigh boric acid and phenolic resin. Dissolve boric acid in ethanol to form a boric acid ethanol solution. Add the phenolic resin into a 250 ml single-necked flask. Under the condition of 25 - 35 °C, add the boric acid ethanol solution to the phenolic resin. After the dropping is completed, react at 55 - 65 °C for 4 h. The obtained reaction solution is distilled under reduced pressure to obtain boron phenolic resin.

[0008] Step 2: Dissolve zirconium oxychloride octahydrate in ethanol to obtain a uniform zirconium-containing solution. Mix the zirconium-containing solution with boron phenolic resin, add a certain amount of anhydrous ethanol. The added ethanol is used to adjust the concentration of the mixed solution. Different amounts of ethanol added can prepare aerogels with different densities. Stir and mix until a uniform mixed solution is obtained. Add phosphoric acid and stir until it is fully dissolved. Add a citric acid solution during stirring and mix evenly. Ultrasonically defoam for 5 - 30 min to obtain a mixed solution.

[0009] Step 3: Use a high-speed disperser to disperse and mix the characteristic fillers evenly, wash and dry them. Mix the aluminum phosphate chromate base liquid and the characteristic fillers evenly to obtain a composite liquid of aluminum phosphate chromate / characteristic fillers for standby.

[0010] Step 4: Treat the mold. Place the fiber felt in the mold. Inject the mixed solution obtained in Step 2 into the mold with the fiber felt. Ultrasonically defoam for 10 - 30 min. Place the mold in a constant-temperature oven and heat at 50 - 80 °C for 6 - 24 h to allow the liquid to undergo preliminary gel curing. Inject the composite liquid obtained in Step 3 into the mold and cure at 50 - 80 °C for 1 - 5 days. A lightweight / heat-insulating / high-emissivity integrated composite material is prepared by co-curing the aluminum phosphate chromate / characteristic fillers composite liquid and the aerogel. The composite liquid in Step 3 forms a high-emissivity surface layer on the surface of the aerogel, and the amount of the composite liquid used is determined according to the thickness requirement.

[0011] Further, in Step 1, the mass ratio of boric acid to phenolic resin is 1:9.

[0012] Further, in Step 2, in the zirconium-containing solution, the mass ratio of ethanol to zirconium element is 3:1; the molar ratio of boron in the boron phenolic resin to the molar amount of zirconium oxychloride is 2:1. The molar ratio of zirconium oxychloride to citric acid is 3 - 7:1. The mass ratio of phosphoric acid to boron phenolic is 1:0.09 - 0.25. The mass ratio of ethanol (the latter) to boron phenolic resin is not greater than 2.3.

[0013] Further, in Step 3, the characteristic fillers are one or more of aluminum powder, hollow microspheres, silicon carbide whiskers, zirconia, zirconium boride, alumina, TaSi2, MoSi2, with a particle size of 1 - 50 μm and excellent dispersibility.

[0014] Further, in Step 3, the mass ratio of the aluminum phosphate chromate base liquid to the characteristic fillers is 10 - 1:1.

[0015] Further, in step four, the mold is processed first. The specific processing method is as follows: First, clean the oil stain on the surface of the mold, then wash and dry it with clean water and ethanol respectively, and finally evenly apply a release agent in the mold.

[0016] Further, in step four, the fiber felt is one or several of glass fiber felt, ceramic fiber felt, aramid fiber felt, and polyester fiber felt.

[0017] Further, in step four, the injection amount of the mixed solution is 1 - 3 cm higher than the fiber felt.

[0018] A lightweight / heat-insulating / high-emissivity integrated composite material prepared by the above preparation method.

[0019] The beneficial effects of the present invention compared with the prior art are as follows:

[0020] First, the lightweight / heat-insulating / high-emissivity integrated composite material of the present invention includes a double-layer structure: the bottom layer material is aerogel with excellent heat-insulating performance, and the outermost layer is a chromium aluminum phosphate surface layer with high emissivity and excellent high-temperature resistance performance. Through this design, the present invention can effectively reduce heat conduction and maintain the stability of the surface temperature by increasing radiative heat loss. Combining the heat-insulating aerogel and the high-emissivity chromium aluminum phosphate surface layer into one body forms a composite material with excellent heat-insulating and radiative characteristics. This structure not only improves the heat control performance of the material but also extends its service life in harsh environments.

[0021] Second, the lightweight / heat-insulating / high-emissivity integrated composite material of the present invention has excellent heat insulation and low density. The thermal conductivity is 0.06 - 0.09 W / (m·k), and the density range is 0.2 - 0.50 g / cm 3 .

[0022] Third, the lightweight / heat-insulating / high-emissivity integrated composite material of the present invention is applicable to many fields in addition to deep space exploration, such as buildings, the energy industry, industrial heating equipment, protection, and military applications. In all these fields, the key advantage of the lightweight / heat-insulating / high-emissivity integrated composite material is that it can effectively reduce the heat transfer to the interior and increase the heat radiation to the environment, thereby improving the durability, efficiency, and safety of the equipment. Description of the Drawings

[0023] Figure 1 It is the infrared spectrum diagram after curing of the zirconium hybrid boron phenolic resin solution obtained in Example 1;

[0024] Figure 2 It is the SEM diagram after high-temperature heat treatment of the fiber felt composite zirconium hybrid boron phenolic aerogel: (a), (b) 1100 °C; (c), (d) 1400 °C; (e), (f) 1500 °C;

[0025] Figure 3 Photographs of the fiber felt composite zirconium hybrid boron phenolic aerogel obtained in Example 1 (a) Microscopic morphology of the lightweight / heat-insulating / high-emissivity integrated composite material after being treated at 1500 °C (b), and emissivity spectrum of the lightweight / heat-insulating / high-emissivity integrated composite material (c). Detailed implementation manners

[0026] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention, without departing from the spirit and scope of the technical solutions of the present invention, shall be covered by the protection scope of the present invention.

[0027] The present invention prepares an aerogel prepolymer with zirconium hybrid boron phenolic resin, prepares a composite solution by compounding a chromium aluminum phosphate-based liquid and characteristic fillers, injects the chromium aluminum phosphate / characteristic filler composite solution into a mold filled with the aerogel prepolymer, and prepares a lightweight / heat-insulating / high-emissivity integrated composite material by a co-curing method. The chromium aluminum phosphate surface layer of the composite material of the present invention has a high emissivity (emissivity ε>0.93 in the range of 3-18 μm), can more quickly dissipate heat to the surrounding environment by infrared radiation, and can effectively reduce the surface temperature; at the same time, the aerogel inner layer prepared by the present invention has a low thermal conductivity, can effectively reduce the transfer of heat to the inside, and protects internal devices from heat erosion. The lightweight / heat-insulating / high-emissivity integrated composite material of the present invention realizes the dual advantages of heat insulation and high-efficiency radiation by reasonably combining the chromium aluminum phosphate surface layer and the aerogel inner layer, can operate for a long time under high-temperature environmental conditions, and is applicable to fields such as aerospace, automotive industry, energy systems, and construction to improve the thermal control performance and energy efficiency of the system.

[0028] Example 1

[0029] Step 1: Weigh 3.84 g of boric acid and 34.56 g of phenolic resin. Dissolve the boric acid in ethanol to form a boric acid ethanol solution. Add the phenolic resin to a 250 ml single-necked flask, and dropwise add the boric acid ethanol solution to the flask at 30 °C. After the dropping is completed, react at 60 °C for 4 h, and subject the obtained reaction solution to vacuum distillation for 0.5 h to obtain boron phenolic resin.

[0030] Step 2: Dissolve 10 g of zirconium oxychloride octahydrate in 30 g of ethanol to obtain a uniform zirconium-containing solution; mix the zirconium-containing solution with 34.8 g of boron phenolic resin, add 50 g of absolute ethanol, stir and mix until a uniform mixed solution is obtained; add 5.22 g of phosphoric acid and stir until fully dissolved; add 1.260 g of citric acid solution during stirring and mix evenly, and remove bubbles by ultrasonic treatment for 5 min to obtain a mixed solution, as Figure 1As shown, the B-O-C chain indicates that the boron compound is introduced into the structure of the resin through chemical bonding, so that part of the B atoms are inserted into the organic aerogel network structure formed by the phenolic resin. The Zr-O-Zr chain and Zr-O-C chain indicate that the zirconium oxychloride dehydrates and condenses to crosslink with each other to form a zirconia gel hybridized into the boron phenolic aerogel. There is a chemical connection between the zirconia gel network and the organic gel network formed by the phenolic resin.

[0031] Step 3: Use a high-speed disperser to disperse and uniformly mix 10 g of silicon carbide whiskers, 30 g of zirconia, and 20 g of zirconium diboride filler, grind, wash, and dry. Mix 5 parts by weight of the chromium phosphate-aluminum base liquid and 1 part by weight of the characteristic filler evenly to obtain a chromium phosphate-aluminum / characteristic filler composite liquid for standby.

[0032] Step 4: First, clean the oil stain on the surface of the mold, then wash and dry it with clean water and ethanol respectively, and finally evenly apply a release agent in the mold. Place the aluminosilicate fiber felt in the mold, inject the solution into the mold with the fiber felt, remove bubbles by ultrasonic for 15 min, and place the mold in a constant-temperature oven at 60 °C for heating for 24 h to obtain an aerogel. As Figure 2 shown, after treatment at 1100 °C, the surface of part of the fibers begins to be damaged and lost, and the inside is intact. The fiber felt still has a supporting effect. At 1400 °C, the inside of the fibers is damaged, and there are intact fibers interspersed in the material. After heat treatment at 1500 °C, the aluminosilicate fiber felt fibers decompose and undergo a carbothermal reduction reaction with amorphous carbon to generate SiC, leaving a large number of micron-sized holes on the surface of the material. SiC particles and nanowires are generated inside the holes, preventing the holes from collapsing. The results show that the fiber felt has good high-temperature resistance and can stably exist in the aerogel below 1400 °C to maintain the stability of the microstructure. Inject the composite liquid obtained in Step 3 into the mold and cure it at 60 °C for 72 hours to obtain a lightweight / heat-insulating / high-emissivity integrated composite material.

[0033] Example 2

[0034] Step 1: Weigh 3.84 g of boric acid and 34.56 g of phenolic resin. Dissolve the boric acid in ethanol to form a boric acid ethanol solution. Add the phenolic resin to a 250 ml single-necked flask, and dropwise add the boric acid ethanol solution to the flask at 30 °C. After the addition is complete, react at 60 °C for 4 h, and subject the resulting reaction solution to vacuum distillation for 0.5 h to obtain a boron phenolic resin.

[0035] Step 2: Dissolve 10 g of zirconium oxychloride octahydrate in 30 g of ethanol to obtain a uniform zirconium-containing solution; mix the zirconium-containing solution with 34.8 g of boron phenolic resin, add 50 g of absolute ethanol, stir and mix until a uniform mixed solution is obtained; add 5.22 g of phosphoric acid and stir until fully dissolved; add 1.260 g of citric acid solution during stirring and mix evenly, and remove bubbles by ultrasonic for 5 min to obtain a mixed solution.

[0036] Step 3: Use a high-speed disperser to disperse and uniformly mix 10 g of silicon carbide whiskers, 30 g of zirconia, 20 g of zirconium diboride, 10 g of alumina and other characteristic fillers, grind, wash and dry them, and uniformly mix 10 parts by weight of the chromium aluminum phosphate base liquid and 1 part by weight of the characteristic fillers to obtain a chromium aluminum phosphate / characteristic filler composite liquid for standby;

[0037] Step 4: First, clean the oil stain on the surface of the mold, then wash and dry it with clean water and ethanol respectively, and finally evenly apply a mold release agent in the mold. Place the mullite fiber felt in the mold, inject the solution into the mold with the fiber felt, remove bubbles by ultrasonic for 15 min, and place the mold in a constant temperature oven at 60 °C for 24 h. Inject the composite liquid obtained in Step 3 into the mold and cure it at 60 °C for 72 hours to obtain a lightweight / heat-insulating / high-emissivity integrated composite material.

[0038] The present invention successfully prepares a high-temperature-resistant composite material. The bottom aerogel material has good high-temperature stability and heat-insulating performance, and the surface layer material has excellent emissivity. By combining the two, while resisting extreme thermal loads, the surface heat energy is efficiently dissipated to the external environment through high radiation efficiency, reducing the heat transfer to the interior. This heat-insulating heat-radiation synergistic mechanism can significantly reduce the heat conduction to the interior of the aircraft, thereby protecting key components such as the load-bearing structure and the avionics system from the risk of thermal failure.

[0039] The above are only the implementation schemes of the present invention. The present invention is not limited to the above specific implementation manners. Those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. Any technical solutions based on the idea of the present invention fall within the protection scope of the present invention. Any changes and related substitutions that occur to those skilled in the art within the technical scope of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a lightweight / thermal insulation / high-emission integrated composite material, characterized in that: The method is: Step 1, weighing boric acid and phenolic resin, dissolving boric acid in ethanol to form a boric acid ethanol solution, adding the boric acid ethanol solution to the phenolic resin at 25-35° C., after the dropwise addition is completed, reacting at 55-65° C. for 4 hours, and distilling the obtained reaction solution under reduced pressure to obtain a boron phenolic resin; Step 2: dissolving zirconium oxychloride octahydrate in ethanol to obtain a uniform zirconium-containing solution, mixing the zirconium-containing solution with boron phenolic resin, adding a certain amount of anhydrous ethanol, stirring and mixing until a uniform mixed solution is obtained, adding phosphoric acid, stirring until fully dissolved, adding citric acid solution during stirring and mixing evenly, and ultrasonically degassing for 5 to 30 minutes to obtain a mixed solution; Step 3: Use a high-speed disperser to evenly disperse and mix the characteristic filler, wash and dry, and evenly mix the aluminum chromium phosphate base liquid and the characteristic filler to obtain an aluminum chromium phosphate / characteristic filler composite liquid for standby use; Step 4: Treat the mold, place the fiber felt in the mold, inject the mixed solution obtained in step 2 into the mold with the fiber felt, perform ultrasonic degassing for 10 to 30 minutes, place the mold in a constant temperature oven and heat it at 50 to 80°C for 6 to 24 hours, inject the composite liquid obtained in step 3 into the mold, and cure it at 50 to 80°C for 1 to 5 days to obtain a lightweight / thermal insulation / high-emission integrated composite material.

2. The method for preparing a lightweight / thermal insulation / high emissivity integrated composite material according to claim 1, characterized in that: In step 1, the mass ratio of the boric acid to the phenolic resin is 1:

9.

3. The method for preparing a lightweight / thermal insulation / high emissivity integrated composite material according to claim 1, characterized in that: In step 2, in the zirconium-containing solution, the mass ratio of ethanol to zirconium element is 3:1; the molar ratio of boron in the boron phenolic resin to the molar ratio of zirconium oxychloride is 2:1, the molar ratio of zirconium oxychloride to citric acid is 3-7:1, and the mass ratio of phosphoric acid to boron phenolic resin is 1:0.09-0.

25.

4. The method for preparing a lightweight / thermal insulation / high emissivity integrated composite material according to claim 1, characterized in that: In step three, the characteristic filler is one or more of aluminum powder, hollow microspheres, silicon carbide whiskers, zirconium oxide, zirconium boride, alumina, TaSi2, and MoSi2, and the particle size is 1 to 50 μm.

5. The method for preparing a lightweight / thermal insulation / high emissivity integrated composite material according to claim 1, characterized in that: In step three, the mass ratio of the aluminum chromium phosphate base liquid to the characteristic filler is 10 to 1:

1.

6. The method for preparing a lightweight / thermal insulation / high emissivity integrated composite material according to claim 1, characterized in that: In step 4, the mold is first processed. The specific processing method is: first clean the oil stains on the surface of the mold, then clean and dry it with clean water and ethanol respectively, and finally evenly apply a release agent in the mold.

7. The method for preparing a lightweight / thermal insulation / high emissivity integrated composite material according to claim 1, characterized in that: In step 4, the fiber felt is one or more of glass fiber felt, ceramic fiber felt, aramid fiber felt, and polyester fiber felt.

8. The method for preparing a lightweight / heat-insulating / high-emission integrated composite material according to claim 1, characterized in that: In step 4, the amount of mixed solution injected is 1-3 cm higher than the fiber felt.

9. A lightweight / heat-insulating / high-emissivity integrated composite material prepared by the preparation method of claims 1 to 8.

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