High-temperature-resistant honeycomb sandwich wave-absorbing structure and preparation method thereof

Abstract

The present application relates to wave-absorbing structure technical field, especially relates to a kind of honeycomb sandwich wave-absorbing structure and preparation method thereof of high temperature resistance.The present application embodiment provides a kind of preparation method of high temperature resistance honeycomb sandwich wave-absorbing structure:(1) pyrolytic carbon coating and silicon carbide coating are prepared in turn on the surface of carbon fiber, to obtain modified carbon fiber;(2) the modified carbon fiber, high temperature resistant resin and solvent are mixed uniformly, to obtain high temperature resistant wave-absorbing slurry;(3) high temperature resistant honeycomb structure is immersed in the high temperature resistant wave-absorbing slurry, after heating and curing, high temperature resistant wave-absorbing honeycomb is obtained;(4) high temperature resistant fiber cloth impregnated with high temperature resistant resin is laid and cured, to obtain skin;(5) along the thickness direction, the skin, the high temperature resistant wave-absorbing honeycomb and the reflector are cured in turn, to obtain the high temperature resistance honeycomb sandwich wave-absorbing structure.The present application embodiment provides a kind of honeycomb sandwich wave-absorbing structure and preparation method thereof, can provide a kind of high temperature resistance honeycomb sandwich wave-absorbing structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wave-absorbing structures, and particularly relates to a high-temperature-resistant honeycomb sandwich wave-absorbing structure and a preparation method thereof. BACKGROUND

[0002] The development of radar detection technology puts forward higher and higher requirements for the low-scattering performance of flight targets.

[0003] In the related art, the honeycomb sandwich wave-absorbing structure can be used to make the flight target have low-scattering performance. However, some special parts of the flight target need to withstand high temperature and high-speed hot gas impact, and the local working temperature will reach more than 1000 DEG C. The existing honeycomb sandwich wave-absorbing structure will fail at high temperature.

[0004] Therefore, in view of the above problems, there is an urgent need for a high-temperature-resistant honeycomb sandwich wave-absorbing structure and a preparation method thereof. SUMMARY

[0005] The present application provides a honeycomb sandwich wave-absorbing structure and a preparation method thereof, which can provide a high-temperature-resistant honeycomb sandwich wave-absorbing structure.

[0006] In a first aspect, the present application provides a preparation method of a high-temperature-resistant honeycomb sandwich wave-absorbing structure, comprising:

[0007] (1) preparing a pyrolytic carbon coating and a silicon carbide coating on the surface of carbon fiber in sequence to obtain modified carbon fiber;

[0008] (2) mixing the modified carbon fiber, high-temperature-resistant resin and solvent uniformly to obtain high-temperature-resistant wave-absorbing slurry;

[0009] (3) immersing the high-temperature-resistant honeycomb structure in the high-temperature-resistant wave-absorbing slurry, and heating and curing to obtain a high-temperature-resistant wave-absorbing honeycomb;

[0010] (4) curing the high-temperature-resistant fiber cloth impregnated with high-temperature-resistant resin to obtain a skin;

[0011] (5) curing the skin, the high-temperature-resistant wave-absorbing honeycomb and the reflecting layer in sequence along the thickness direction to obtain the high-temperature-resistant honeycomb sandwich wave-absorbing structure.

[0012] In a possible design, in step (1), the pyrolytic carbon coating is prepared by a gas phase chemical deposition method, the source gas for preparing the pyrolytic carbon coating is propane, the deposition temperature is 1000-1200 DEG C, the heating rate is 8-12 DEG C / min, the deposition pressure is 240-260 Pa, and the deposition time is 0.8-1.2 h.

[0013] In a possible design, in step (1), the silicon carbide coating is prepared by a gas phase chemical deposition method, a source gas for preparing the silicon carbide coating is trichloromethylsilane, a deposition temperature is 1000-1200 ℃, a temperature rising rate is 8-12 ℃ / min, a deposition pressure is 240-260 Pa, and a deposition time is 3.8-4.2 h.

[0014] In a possible design, step (2) comprises:

[0015] 80-120 parts of the modified carbon fiber, 380-420 parts of the high-temperature-resistant resin, and 180-220 parts of the solvent are mixed, and then stirred at 75-85 ℃ and at a speed of 400-500 r / min for 25-35 min;

[0016] ultrasonic oscillation is performed for 10-20 min;

[0017] 280-320 parts of the solvent are added, and then stirred at a speed of 400-500 r / min for 25-35 min again;

[0018] ultrasonic oscillation is performed for 10-20 min, and a high-temperature-resistant wave-absorbing slurry is obtained.

[0019] In a possible design, in step (2), the high-temperature-resistant resin comprises an organic polysilazane resin, and the solvent is acetone.

[0020] In a possible design, in step (3), the high-temperature-resistant honeycomb comprises a glass fiber honeycomb or a quartz fiber honeycomb.

[0021] In a possible design, in step (4), the high-temperature-resistant resin comprises a polyimide resin, the high-temperature-resistant fiber cloth comprises a glass fiber cloth or a quartz fiber cloth, and the high-temperature-resistant resin is coated on the high-temperature-resistant fiber cloth by a wet flow casting film forming mode.

[0022] In a possible design, in step (5), the skin, the high-temperature-resistant wave-absorbing honeycomb, and the reflective layer are combined by a high-temperature-resistant adhesive film.

[0023] In a possible design, the reflective layer comprises at least one layer of carbon fiber cloth.

[0024] In a second aspect, an embodiment of the present application provides a high-temperature-resistant honeycomb sandwich wave-absorbing structure, which is prepared by any of the preparation methods described above.

[0025] Compared with the prior art, the present application has at least the following beneficial effects:

[0026] In the present embodiment, silicon carbide has excellent high-temperature resistance, but its wave-absorbing capacity is not ideal. Therefore, a silicon carbide coating is arranged on the surface of the carbon fiber to obtain a high-temperature-resistant carbon fiber with better wave-absorbing effect. It should be noted that direct deposition of silicon carbide on the carbon fiber will cause damage to the carbon fiber, and therefore, a pyrolytic carbon coating needs to be arranged on the carbon fiber first, and then a silicon carbide coating is arranged on the pyrolytic carbon coating. The pyrolytic carbon coating and the silicon carbide coating can be arranged by a chemical vapor deposition method. After obtaining the modified carbon fiber with high-temperature resistance and high wave-absorbing performance, the obtained modified carbon fiber, high-temperature-resistant resin, and solvent are uniformly mixed to obtain a high-temperature-resistant wave-absorbing slurry. The high-temperature-resistant honeycomb structure is immersed in the high-temperature-resistant wave-absorbing slurry, and after sufficient immersion, the high-temperature-resistant honeycomb structure reaches a preset weight gain, and then solidification is performed to obtain a high-temperature-resistant wave-absorbing honeycomb. After the high-temperature-resistant resin-impregnated high-temperature-resistant fiber cloth is laid and solidified, a skin for wave transmission is obtained. The skin, the high-temperature-resistant wave-absorbing honeycomb, and the reflecting layer are sequentially solidified along the thickness direction to obtain a high-temperature-resistant honeycomb sandwich wave-absorbing structure. When the honeycomb sandwich wave-absorbing structure is used, the skin faces outward, electromagnetic waves enter the honeycomb through the wave-transmitting skin, are absorbed in the honeycomb, and the remaining part is reflected by the reflecting layer and is again absorbed by the honeycomb layer. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0028] Figure 1 is a preparation flow chart of a high-temperature-resistant honeycomb sandwich wave-absorbing structure provided by the present embodiment;

[0029] Figure 2 is the reflectivity test result of the high-temperature-resistant sandwich wave-absorbing material made in Example 1 at room temperature and high temperature (300°C);

[0030] Figure 3 is the reflectivity test result of the high-temperature-resistant sandwich wave-absorbing material made in Example 2 at room temperature and high temperature (300°C);

[0031] Figure 4 is the reflectivity test result of the high-temperature-resistant sandwich wave-absorbing material made in Example 3 at room temperature and high temperature (300°C);

[0032] Figure 5 is the reflectivity test result of the high-temperature-resistant sandwich wave-absorbing material made in Comparative Example 1 at room temperature and high temperature (300°C);

[0033] Figure 6The high-temperature-resistant sandwich structure wave-absorbing material prepared in Comparative Example 2 was tested for reflectivity at room temperature and at high temperature (300 DEG C). DETAILED DESCRIPTION

[0034] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0035] In the description of the embodiments of the present application, unless explicitly defined and limited otherwise, the terms "first", "second" are only used for the purpose of description and cannot be understood as indicating or implying relative importance; unless otherwise specified or explained, the term "multiple" means two or more; the terms "connection", "fixation" and the like should be understood in a broad sense, for example, "connection" can be fixed connection, can be detachable connection, or integral connection, or electrical connection; can be directly connected, or indirectly connected through an intermediate medium. For a person of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0036] As shown in Figure 1 The present application provides a preparation method of a high-temperature-resistant honeycomb sandwich wave-absorbing structure, comprising:

[0037] (1) preparing a pyrolytic carbon coating and a silicon carbide coating on the surface of carbon fiber in sequence to obtain modified carbon fiber;

[0038] (2) mixing the modified carbon fiber, high-temperature-resistant resin and solvent uniformly to obtain high-temperature-resistant wave-absorbing slurry;

[0039] (3) dipping the high-temperature-resistant honeycomb structure in the high-temperature-resistant wave-absorbing slurry, and heating and curing to obtain a high-temperature-resistant wave-absorbing honeycomb;

[0040] (4) curing the high-temperature-resistant fiber cloth impregnated with high-temperature-resistant resin to obtain a skin;

[0041] (5) curing the skin, the high-temperature-resistant wave-absorbing honeycomb and the reflecting layer in sequence along the thickness direction to obtain a high-temperature-resistant honeycomb sandwich wave-absorbing structure.

[0042] In the embodiment, the silicon carbide has excellent high-temperature resistance, but its wave-absorbing capacity is not ideal. Therefore, a silicon carbide coating is arranged on the surface of the carbon fiber to obtain a high-temperature-resistant carbon fiber with good wave-absorbing effect. It should be noted that the silicon carbide is directly deposited on the carbon fiber, which may cause damage to the carbon fiber. Therefore, a pyrolytic carbon coating is arranged on the carbon fiber first, and then a silicon carbide coating is arranged on the pyrolytic carbon coating. The pyrolytic carbon coating and the silicon carbide coating can be arranged by a chemical vapor deposition method. After the modified carbon fiber with high-temperature resistance and high wave-absorbing performance is obtained, the modified carbon fiber, the high-temperature-resistant resin, and the solvent are uniformly mixed to obtain a high-temperature-resistant wave-absorbing slurry. The high-temperature-resistant honeycomb structure is immersed in the high-temperature-resistant wave-absorbing slurry, and after sufficient immersion, the high-temperature-resistant honeycomb structure reaches a preset weight gain, and then solidification is performed to obtain a high-temperature-resistant wave-absorbing honeycomb. After the high-temperature-resistant resin-impregnated high-temperature-resistant fiber cloth is laid and solidified, a skin for wave transmission is obtained. The skin, the high-temperature-resistant wave-absorbing honeycomb, and the reflecting layer are sequentially solidified in the thickness direction to obtain a high-temperature-resistant honeycomb sandwich wave-absorbing structure. When the honeycomb sandwich wave-absorbing structure is used, the skin faces outward, electromagnetic waves enter the honeycomb through the wave-transmitting skin, are absorbed in the honeycomb, and the remaining part is reflected by the reflecting layer and is again absorbed by the honeycomb layer.

[0043] In some embodiments of the present application, in step (1), the pyrolytic carbon coating is prepared by a chemical vapor deposition method, a source gas for preparing the pyrolytic carbon coating is propane, a deposition temperature is 1000-1200℃, a temperature rising rate is 8-12℃ / min, a deposition pressure is 240-260Pa, and a deposition time is 0.8-1.2h.

[0044] In some embodiments of the present application, in step (1), the silicon carbide coating is prepared by a chemical vapor deposition method, a source gas for preparing the silicon carbide coating is trichloromethylsilane, a deposition temperature is 1000-1200℃, a temperature rising rate is 8-12℃ / min, a deposition pressure is 240-260Pa, and a deposition time is 3.8-4.2h.

[0045] In some embodiments of the present application, step (2) comprises:

[0046] After 80-120 parts of the modified carbon fiber, 380-420 parts of the high-temperature-resistant resin, and 180-220 parts of the solvent are mixed, stirring is performed at 75-85℃ and at a speed of 400-500r / min for 25-35min;

[0047] Ultrasonic oscillation is performed for 10-20min;

[0048] After 280-320 parts of the solvent are added, stirring is again performed at a speed of 400-500r / min for 25-35min;

[0049] Ultrasonic oscillation is performed for 10-20min to obtain the high-temperature-resistant wave-absorbing slurry.

[0050] In some embodiments of the present application, in step (2), the high-temperature-resistant resin comprises an organic polysilazane resin, and the solvent is acetone.

[0051] In some embodiments of the present application, in step (3), the high-temperature-resistant honeycomb comprises a glass fiber honeycomb or a quartz fiber honeycomb.

[0052] In some specific embodiments, the thickness of the honeycomb is 10 mm. The curing condition is to increase the temperature to 120℃ at a rate of not more than 4℃ / min, keep for 30 mins, continue to increase the temperature to 180℃ at a rate of not more than 4℃ / min, keep for 2h, and complete the curing.

[0053] In some embodiments of the present application, in step (4), the high-temperature-resistant resin comprises a polyimide resin, and the high-temperature-resistant fiber cloth comprises a glass fiber cloth or a quartz fiber cloth, and the high-temperature-resistant resin is coated on the high-temperature-resistant fiber cloth by a wet flow casting film forming method.

[0054] In this embodiment, the thickness of the single high-temperature-resistant fiber cloth is 0.1 mm, the slurry blade coating thickness is 0.2 mm±0.05 mm, the drying tunnel temperature is 70℃-80℃, and the drying time is 30 mins. The wave-transparent prepreg is covered with release paper on the top and bottom.

[0055] In some embodiments of the present application, in step (5), the skin, the high-temperature-resistant wave-absorbing honeycomb, and the reflective layer are combined by a high-temperature-resistant adhesive film.

[0056] In this embodiment, the high-temperature-resistant adhesive film is a high-temperature-resistant polyimide (PI) adhesive film.

[0057] The skin is designed to have a thickness of 2 mm, 10 layers of wave-transparent prepreg are laid, and hot pressing and curing are performed. The curing condition is to increase the temperature to 350℃ at a rate of 2℃ / min, apply a pressure of 2.5 MPa, continue to increase the temperature to 370℃ at a rate of 2℃ / min, keep for 2.5h, naturally cool to 80℃, release the pressure, naturally cool to below 40℃, and demold.

[0058] The curing in step (5) comprises: increasing the temperature to 80℃ at a rate of not more than 4℃ / min, applying a curing pressure of 0.3 MPa, keeping for 3h, continuing to increase the temperature to 100℃, keeping for 1h, continuing to increase the temperature to 260℃, keeping for 1h, continuing to increase the temperature to 300℃, keeping for 2h, naturally cooling to 80℃, releasing the pressure, naturally cooling to 40℃, and demolding.

[0059] In some embodiments of the present application, the reflective layer comprises at least one layer of carbon fiber cloth.

[0060] The present application provides a high-temperature-resistant honeycomb sandwich wave-absorbing structure prepared by any of the above preparation methods.

[0061] In order to more clearly illustrate the technical solutions and advantages of the present application, the preparation method of a high-temperature-resistant honeycomb sandwich wave-absorbing structure is described in detail below through several examples.

[0062] Example 1

[0063] S1, a sufficient amount of carbon fiber is weighed, a pyrolytic carbon coating is prepared on the surface of the carbon fiber by chemical vapor deposition, and a silicon carbide coating is prepared on the surface of the carbon fiber again by chemical vapor deposition to modify the carbon fiber;

[0064] S2, 200g of acetone is slowly added to 400g of organic polysilazane resin, the system is heated to 80℃ at a rate of 4℃ / min while stirring manually, and then kept at 80℃, 100g of high-temperature-resistant absorbent is slowly added, stirred until the absorbent and the organic polysilazane resin are mixed uniformly, and ultrasonic oscillation is performed. The mixed absorbent and the organic polysilazane resin are ground twice. 300g of acetone is added to the ground material for dilution, and stirring and ultrasonic oscillation are performed again to prepare a high-temperature-resistant wave-absorbing slurry;

[0065] S3, 50g of glass fiber honeycomb with a thickness of 10mm is weighed and placed in the high-temperature-resistant wave-absorbing slurry, and fully immersed for 15mins. The glass fiber honeycomb is taken out, turned over and immersed again, and this process is repeated three times. The immersed glass fiber honeycomb is placed on a hollow stainless steel mesh, and after the wave-absorbing slurry no longer flows down the honeycomb wall, it is placed in an oven for curing. The honeycomb is continuously turned over during the curing process to prevent uneven immersion of the honeycomb. A high-temperature-resistant wave-absorbing honeycomb core is prepared, and the weight is 150g. If the designed weight is not reached, the immersion process is repeated until the honeycomb reaches the designed weight increase;

[0066] S4, a PI solution is coated on a glass fiber cloth using a wet flow casting film forming method, the thickness is 0.2mm, and release paper is covered on the top and bottom. After drying through an oven, a wave-transparent prepreg is obtained; the wave-transparent prepreg is sealed with a polyethylene bag and stored in a refrigerator at -18℃;

[0067] S5, the wave-transparent prepreg prepared in S4 is taken out of the polyethylene bag after being placed at room temperature, the release paper is removed, and the layers are laid. A flat mold with release paper is used to lay 10 layers of wave-transparent prepreg on the mold, 2mm spacers are placed around the mold for positioning, and the mold is closed for curing. The autoclave is heated to 350℃ at a rate of 2℃ / min, a curing pressure of 2.5MPa is applied, and the temperature is further increased to 370℃ at a rate of 2℃ / min, and the temperature is kept for 2.5h. The temperature is naturally lowered to 80℃, and the pressure is released. The temperature is naturally lowered to below 40℃, and the mold is removed to obtain a wave-transparent skin;

[0068] S6, the flat plate layer, the order from bottom to top is flat plate mold lower mold, 2 layers of carbon fiber cloth, 1 layer of PI adhesive film, the high-temperature-resistant wave-absorbing honeycomb core prepared by S3, 1 layer of PI adhesive film, the wave-transparent skin prepared by S5, flat plate mold upper mold;

[0069] S7, the sample of S6 is placed in a hot press tank, the temperature is increased to 80℃ at a rate of 4℃ / min, a curing pressure of 0.3MPa is applied, the temperature is kept for 3h, the temperature is continuously increased to 100℃, the temperature is kept for 1h, the temperature is continuously increased to 260℃, the temperature is kept for 1h, the temperature is continuously increased to 300℃, the temperature is kept for 2h, the temperature is naturally decreased to 80℃, the pressure is released, the temperature is naturally decreased to 40℃, the sample is taken out after demolding, and a high-temperature-resistant sandwich structure wave-absorbing material flat plate sample based on a wave-absorbing honeycomb is obtained;

[0070] S8, the sample prepared in S7 is taken out and trimmed into a size of 300*300mm to be measured, and the reflectivity test at normal temperature and high temperature (300℃) is carried out according to GJB2038A-2011, and the results are shown in Figure 2 .

[0071] Example 2

[0072] S1, a sufficient amount of carbon fiber is weighed, a pyrolytic carbon coating is prepared on the surface of the carbon fiber by chemical vapor deposition, and the carbon fiber is modified by again preparing a silicon carbide coating on the surface of the carbon fiber by chemical vapor deposition;

[0073] S2, 200g of acetone is slowly added to 400g of organic polysilazane resin, the system is heated to 80℃ at a rate of 4℃ / min while stirring manually, 50g of high-temperature-resistant absorbent is slowly added, stirring is carried out until the absorbent and the organic polysilazane resin are uniformly mixed, and ultrasonic oscillation is carried out. The uniformly mixed absorbent and the organic polysilazane resin are ground twice. 300g of acetone is added to the ground material for dilution, and stirring and ultrasonic oscillation are carried out again, and a high-temperature-resistant wave-absorbing slurry is prepared;

[0074] S3, 50g of glass fiber honeycomb with a thickness of 10mm is weighed, and is placed in the high-temperature-resistant wave-absorbing slurry, and is fully immersed for 15mins. The glass fiber honeycomb is taken out, is turned over and is fully immersed again, and the process is repeated three times. The immersed glass fiber honeycomb is taken out, is placed on a hollow stainless steel mesh, and after the wave-absorbing slurry no longer flows down along the honeycomb wall, is placed in an oven for curing. The honeycomb is continuously turned over during the curing process to prevent uneven immersion of the honeycomb. A high-temperature-resistant wave-absorbing honeycomb core is prepared, and the weight is 150g. If the designed weight is not reached, the immersion process is repeated until the honeycomb reaches the designed weight increase;

[0075] S4, the PI solution was coated on the glass fiber cloth using a wet flow casting method, with a thickness of 0.2 mm, and covered with release paper on both sides. After drying through the oven, a wave-transparent prepreg was obtained; the wave-transparent prepreg was sealed in a polyethylene bag and stored in a refrigerator at -18°C;

[0076] S5, the wave-transparent prepreg prepared in S4 was taken out of the polyethylene bag after being placed at room temperature, the release paper was removed, and the layers were laid. A flat mold was adhered with release paper, 10 layers of wave-transparent prepreg were laid on the mold, 2 mm spacers were placed around the mold for positioning, and the mold was closed and cured. The autoclave was heated to 350°C at a rate of 2°C / min, a curing pressure of 2.5 MPa was applied, the temperature was continued to be raised to 370°C at a rate of 2°C / min, and the temperature was maintained for 2.5 h. The temperature was naturally lowered to 80°C, and the pressure was released. The temperature was naturally lowered to below 40°C, the mold was removed, and a wave-transparent skin was prepared;

[0077] S6, flat layering, in order from bottom to top: flat mold lower mold, 2 layers of carbon fiber cloth, 1 layer of PI adhesive film, high-temperature-resistant wave-absorbing honeycomb core prepared in S3, 1 layer of PI adhesive film, wave-transparent skin prepared in S5, flat mold upper mold;

[0078] S7, the sample of S6 was placed in an autoclave, heated to 80°C at a rate of 4°C / min, a curing pressure of 0.3 MPa was applied, the temperature was maintained for 3 h, the temperature was continued to be raised to 100°C, the temperature was maintained for 1 h, the temperature was continued to be raised to 260°C, the temperature was maintained for 1 h, the temperature was continued to be raised to 300°C, the temperature was maintained for 2 h, the temperature was naturally lowered to 80°C, the pressure was released, the temperature was naturally lowered to 40°C, the mold was removed, and a wave-absorbing material flat sample based on wave-absorbing honeycomb sandwich structure was obtained;

[0079] S8, the sample prepared in S7 was taken out and trimmed to a size of 300*300 mm for testing, and the reflectivity test was performed at room temperature and high temperature (300°C) according to GJB2038A-2011, and the results are shown in Figure 3 .

[0080] Example 3

[0081] S1, a sufficient amount of carbon fiber was weighed, a pyrolytic carbon coating was prepared on the surface of the carbon fiber by chemical vapor deposition, and a silicon carbide coating was prepared on the surface of the carbon fiber again by chemical vapor deposition to modify the carbon fiber;

[0082] S2, 200g of acetone was slowly added to 400g of organic polysilazane resin, the system was heated to 80°C at a rate of 4°C / min while stirring manually, and then maintained; 200g of high-temperature-resistant absorbent was slowly added, stirred until the absorbent and organic polysilazane resin were uniformly mixed, and ultrasonic oscillation was performed. The uniformly mixed absorbent and organic polysilazane resin were ground twice. 300g of acetone was added to the ground material for dilution, and stirring and ultrasonic oscillation were performed again to prepare a high-temperature-resistant wave-absorbing slurry;

[0083] S3, weigh 50 g of glass fiber honeycomb with a thickness of 10 mm, put it into the high-temperature absorbing paste, and fully immerse it for 15 mins. Take out the glass fiber honeycomb, turn it over and immerse it again. Repeat this process three times. Take out the immersed glass fiber honeycomb and place it on a hollowed-out stainless steel mesh. After the absorbing paste no longer flows down the honeycomb wall, place it in an oven for curing. Turn it over constantly during the curing process to prevent uneven immersion of the honeycomb from top to bottom. A high-temperature absorbing honeycomb core is obtained, with a weight of 150 g. If the designed weight is not reached, repeat the immersion process until the honeycomb reaches the designed weight increase;

[0084] S4, use the wet-laid film forming method to coat the PI solution on the glass fiber cloth with a thickness of 0.2 mm, and cover it with release paper on both sides. After drying through the oven, a wave-transparent prepreg is obtained. Seal the wave-transparent prepreg in a polyethylene bag and store it in a refrigerator at -18°C;

[0085] S5, take out the wave-transparent prepreg prepared in S4 from the polyethylene bag after it reaches room temperature, remove the release paper, and lay it up. A flat mold with release paper is used to lay 10 layers of wave-transparent prepreg on the mold, with 2 mm spacers placed around the periphery for positioning. The mold is closed and cured. The autoclave is heated to 350°C at a rate of 2°C / min, and a curing pressure of 2.5 MPa is applied. The temperature is then increased to 370°C at a rate of 2°C / min, and the temperature is maintained for 2.5 h. The temperature is then naturally lowered to 80°C, and the pressure is released. The temperature is then naturally lowered to below 40°C, and the mold is removed. A wave-transparent skin is obtained.

[0086] S6, flat lay, in order from bottom to top: flat mold lower mold, 2 layers of carbon fiber cloth, 1 layer of PI adhesive film, high-temperature absorbing honeycomb core prepared in S3, 1 layer of PI adhesive film, wave-transparent skin prepared in S5, flat mold upper mold;

[0087] S7, place the sample of S6 in an autoclave, heat it to 80°C at a rate of 4°C / min, apply a curing pressure of 0.3 MPa, and maintain the temperature for 3 h. Continue to heat it to 100°C, maintain the temperature for 1 h, continue to heat it to 260°C, maintain the temperature for 1 h, continue to heat it to 300°C, maintain the temperature for 2 h, naturally cool it to 80°C, release the pressure, naturally cool it to 40°C, remove the mold, and obtain a wave-absorbing material flat sample based on absorbing honeycomb.

[0088] S8, trim the sample prepared in S7 to a size of 300*300 mm, and test the reflectivity at room temperature and high temperature (300°C) according to GJB2038A-2011. The results are shown in Table 1. Figure 4

[0089] Comparative Example 1

[0090] ​S1, take enough carbon fiber, prepare pyrolytic carbon coating on the surface of carbon fiber by chemical vapor deposition method, and then modify the carbon fiber by preparing silicon carbide coating on the surface of carbon fiber again by chemical vapor deposition method;

[0091] S2, slowly add 200g of acetone to 400g of organic polysilazane resin, heat the system to 80℃ at a rate of 4℃ / min while stirring manually, and keep it at this temperature, slowly add 80g of high-temperature-resistant absorbent, stir until the absorbent and organic polysilazane resin are evenly mixed, and ultrasonic oscillation. Grind the evenly mixed absorbent and organic polysilazane resin for two times. Add 300g of acetone to dilute the ground material, stir and ultrasonic oscillate again to prepare a high-temperature-resistant wave-absorbing slurry;

[0092] S3, take 50g of aramid fiber honeycomb with a thickness of 10mm, put it into the high-temperature-resistant wave-absorbing slurry, and fully immerse it for 15 minutes. Take out the aramid fiber honeycomb, turn it over and immerse it again. Repeat this process three times. Take out the immersed aramid fiber honeycomb and place it on a hollow stainless steel mesh. After the wave-absorbing slurry no longer flows down the honeycomb wall, place it in an oven for curing. Turn it over constantly during the curing process to prevent uneven immersion of the honeycomb. Prepare a wave-absorbing honeycomb core with a weight of 150g. If the designed weight is not reached, repeat the immersion process until the honeycomb reaches the designed weight increase;

[0093] S4, use the wet-laid film forming method to coat the PI solution on the glass fiber cloth with a thickness of 0.2mm, and cover it with release paper on both sides. After drying through the oven, a wave-transparent prepreg is obtained. Seal the wave-transparent prepreg in a polyethylene bag and store it in a refrigerator at-18℃;

[0094] S5, take out the wave-transparent prepreg prepared in S4 from the polyethylene bag after it reaches room temperature, remove the release paper, and lay it up. Stick release paper on the flat mold, lay 10 layers of wave-transparent prepreg on the mold, position it with 2mm blocks around, and assemble and cure it. Heat the autoclave to 350℃ at a rate of 2℃ / min, apply a curing pressure of 2.5MPa, continue to heat to 370℃ at a rate of 2℃ / min, and keep it at this temperature for 2.5h. Naturally cool to 80℃, and release the pressure. Naturally cool to below 40℃, demold, and prepare a wave-transparent skin;

[0095] S6, flat lay, the sequence from bottom to top is flat mold lower mold, 2 layers of carbon fiber cloth, 1 layer of PI adhesive film, wave-absorbing honeycomb core prepared in S3, 1 layer of PI adhesive film, wave-transparent skin prepared in S5, and flat mold upper mold;

[0096] S7, the sample of S6 was placed in a hot press tank, and the temperature was increased to 80℃ at a rate of 4℃ / min, a curing pressure of 0.3 MPa was applied, and the temperature was kept for 3 h, then the temperature was increased to 100℃, and the temperature was kept for 1 h, then the temperature was increased to 260℃, and the temperature was kept for 1 h, then the temperature was increased to 300℃, and the temperature was kept for 2 h, then the temperature was naturally decreased to 80℃, the pressure was released, and the temperature was naturally decreased to 40℃, then the sample was taken out after demolding, and a high-temperature-resistant sandwich structure wave-absorbing material plate sample based on wave-absorbing honeycomb was obtained;

[0097] S8, the sample prepared in S7 was taken out and trimmed into a size of 300*300 mm, and the reflectivity test at room temperature and high temperature (300℃) was performed according to GJB2038A-2011, and the results are shown in Figure 5 .

[0098] As can be seen from the figure, the material still has good wide-band wave-absorbing performance at room temperature, but the wave-absorbing performance and mechanical properties are both obviously reduced at high temperature (300℃), because the glass fiber has more excellent high-temperature resistance than aramid fiber, and the use of honeycomb material with more excellent high-temperature resistance helps to improve the high-temperature performance of the material.

[0099] Comparative Example 2

[0100] S1, a sufficient amount of carbon fiber was weighed, a pyrolytic carbon coating was prepared on the surface of the carbon fiber by chemical vapor deposition, and the carbon fiber was modified by again preparing a silicon carbide coating on the surface of the carbon fiber by chemical vapor deposition;

[0101] S2, 200 g of acetone was slowly added to 400 g of epoxy resin, stirred uniformly, 80 g of high-temperature-resistant absorbent was slowly added, stirred until the absorbent and the epoxy resin were uniformly mixed, and ultrasonic oscillation was performed. The uniformly mixed absorbent and organic polysilazane resin were ground twice. 300 g of acetone was added to the ground material for dilution, and stirring and ultrasonic oscillation were performed again to prepare a wave-absorbing slurry;

[0102] S3, 50 g of glass fiber honeycomb with a thickness of 10 mm was placed in the wave-absorbing slurry, and was fully immersed for 15 mins, then the glass fiber honeycomb was taken out, turned over and fully immersed again, and this process was repeated three times. The immersed glass fiber honeycomb was placed on a hollow stainless steel mesh, and after the wave-absorbing slurry no longer flowed down the honeycomb wall, it was placed in an oven and heated to 80℃ at a rate of 4℃ / min, and was kept for 4 h. During the curing process, the honeycomb was continuously turned over to prevent uneven immersion of the honeycomb. A wave-absorbing honeycomb core was prepared, and the weight was 150 g. If the designed weight was not reached, the immersion process was repeated until the honeycomb reached the designed weight increase;

[0103] S4, the epoxy resin is coated on the glass fiber cloth by using a wet flow casting film forming method, and the thickness is 0.2 mm, and the glass fiber cloth is covered with release paper up and down. After drying through the oven, a wave-transparent prepreg is obtained; the wave-transparent prepreg is sealed with a polyethylene bag and stored in a refrigerator at-18 DEG C;

[0104] S5, the wave-transparent prepreg prepared in S4 is taken out from the polyethylene bag after being placed at room temperature, the release paper is removed, and the layers are laid, the flat mold is adhered with release paper, 10 layers of wave-transparent prepreg are laid on the mold, 2 mm blocks are placed around for positioning, the mold is closed, the temperature is raised to 80 DEG C at a rate of 4 DEG C / min, and the temperature is kept for 4 h, and a wave-transparent skin is prepared;

[0105] S6, the flat layer is laid, and the sequence from bottom to top is as follows: the lower mold of the flat mold, 2 layers of carbon fiber cloth, 1 layer of epoxy adhesive film, the wave-absorbing honeycomb core prepared in S3, 1 layer of epoxy adhesive film, the wave-transparent skin prepared in S5, and the upper mold of the flat mold;

[0106] S7, the sample in S6 is placed in an oven, the temperature is raised to 80 DEG C at a rate of 4 DEG C / min, the temperature is kept for 4 h, the temperature is naturally lowered to 40 DEG C, the sample is taken out after demolding, and a wave-absorbing material flat sample based on a wave-absorbing honeycomb sandwich structure is obtained;

[0107] S8, the sample prepared in S7 is taken out and trimmed into a size to be measured of 300*300 mm, the reflectivity at room temperature and high temperature (300 DEG C) is tested according to GJB2038A-2011, and the results are shown in Figure 6 .

[0108] As shown in the figure, the material still has good wide-band wave-absorbing performance at room temperature, but the wave-absorbing performance at high temperature (300 DEG C) decreases obviously, and the mechanical properties cannot be measured due to the disintegration of the material at high temperature. It is shown that the application of a high-temperature-resistant resin helps to improve the high-temperature performance of the material.

[0109] In addition, the product obtained in the example can also maintain excellent mechanical properties at high temperature, and the products obtained in the example and the comparative example are tested, and the results are shown in Table 1.

[0110] Table 1: Mechanical property test results of the example and the comparative example

[0111]

[0112] In summary, the high-temperature-resistant wave-absorbing material based on a wave-absorbing honeycomb sandwich structure prepared by the application has excellent wave-absorbing performance and mechanical properties, and the performance is excellent at high temperature (300 DEG C), and has good application prospect.

[0113] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a high-temperature-resistant honeycomb sandwich wave-absorbing structure, characterized in that, The preparation method comprises the following steps: (1) preparing a pyrolytic carbon coating and a silicon carbide coating on the surface of carbon fiber in sequence to obtain modified carbon fiber; (2) uniformly mixing the modified carbon fiber, high-temperature-resistant resin and solvent to obtain high-temperature-resistant wave-absorbing slurry; (3) immersing a high-temperature-resistant honeycomb structure in the high-temperature-resistant wave-absorbing slurry, and then heating and curing to obtain a high-temperature-resistant wave-absorbing honeycomb; (4) laying and curing high-temperature-resistant fiber cloth impregnated with high-temperature-resistant resin to obtain a skin; (5) sequentially curing the skin, the high-temperature-resistant wave-absorbing honeycomb and a reflective layer in the thickness direction to obtain the high-temperature-resistant honeycomb sandwich wave-absorbing structure. In step (1), the pyrolytic carbon coating is prepared by a gas phase chemical deposition method, the source gas for preparing the pyrolytic carbon coating is propane, the deposition temperature is 1000-1200℃, the heating rate is 8-12℃ / min, the deposition pressure is 240-260Pa, and the deposition time is 0.8-1.2h. In step (1), the silicon carbide coating is prepared by a gas phase chemical deposition method, the source gas for preparing the silicon carbide coating is trichloromethylsilane, the deposition temperature is 1000-1200℃, the heating rate is 8-12℃ / min, the deposition pressure is 240-260Pa, and the deposition time is 3.8-4.2h. In step (2), the high-temperature-resistant resin comprises organic polysilazane resin, and the solvent is acetone. In step (3), the high-temperature-resistant honeycomb comprises a glass fiber honeycomb or a quartz fiber honeycomb.

2. The production method according to claim 1, characterized by, In step (2), the following steps are performed in parts by weight: 80-120 parts of the modified carbon fiber, 380-420 parts of the high-temperature-resistant resin and 180-220 parts of the solvent are mixed, and then stirred at 75-85℃ and at a speed of 400-500r / min for 25-35min; ultrasonic oscillation is performed for 10-20min; 280-320 parts of the solvent are added, and then stirred at a speed of 400-500r / min for 25-35min; ultrasonic oscillation is performed for 10-20min to obtain the high-temperature-resistant wave-absorbing slurry.

3. The preparation method according to claim 1, characterized in that, In step (4), the high-temperature-resistant resin comprises polyimide resin, the high-temperature-resistant fiber cloth comprises glass fiber cloth or quartz fiber cloth, and the high-temperature-resistant resin is coated on the high-temperature-resistant fiber cloth by a wet flow casting film forming method.

4. The preparation method according to claim 1, characterized in that, In step (5), the skin, the high-temperature-resistant wave-absorbing honeycomb and the reflective layer are combined by a high-temperature-resistant adhesive film.

5. The preparation method according to claim 1, characterized in that, The reflective layer comprises at least one layer of carbon fiber cloth.

6. A high temperature resistant honeycomb sandwich wave absorbing structure, characterized in that, The preparation method is prepared by any one of claims 1-5.

Images