Organosilicon composite material for improving high-temperature wave-transparent performance through in-situ oxygen release and carbon removal and preparation method thereof

Abstract

The invention relates to an organic silicon composite material capable of improving high-temperature wave-transparent performance through in-situ oxygen release and carbon removal and a preparation method thereof, methyl organic silicon resin (namely a high-molecular compound with a silicon-oxygen bond (Si-O) as a main chain and methyl (CH3) as a side chain) is selected as a precursor, toluene and ethanol are mixed according to a ratio of (4-5): 1 to serve as a solvent, a resin solution is prepared through mixing, and the high-temperature wave-transparent performance is improved through in-situ oxygen release and carbon removal. Mixing and adding cerium octanoate and cerium acetylacetonate into the resin solution according to a certain proportion; and compounding the resin solution with the fiber preform through a vacuum impregnation process, and carrying out impregnation-curing to obtain the organic silicon composite material with good dielectric properties. Compared with the prior art, the composite material has the function of stable dielectric property at high temperature, and can be applied to missile radar radome materials.

Description

Technical Field

[0001] The present invention relates to the technical field of organic wave-transmitting materials, and in particular to an organic silicon composite material having improved high-temperature wave-transmitting performance through in-situ oxygen release and carbon removal, and a preparation method thereof. Background Art

[0002] In the field of aerospace technology, the material properties of radar antenna covers are crucial to system effectiveness. Fiber-reinforced silicone resin composites are widely used in practical applications due to their mature preparation process, low cost, and short cycle time. However, during high Mach number flight, the large amount of organic groups in ordinary resin-based composites are easily decomposed in the high-temperature environment, producing a large amount of free carbon or carbon compounds, which changes the electromagnetic properties of the material and causes large fluctuations in the dielectric constant and loss tangent, affecting the quality and accuracy of radar signal transmission. Therefore, the research and development of fiber-reinforced silicone resin composites with stable dielectric properties at high temperatures has become a top priority. This is related to the reliability and survivability of aerospace systems and is of great significance to the development of future hypersonic vehicles.

[0003] Patent CN103387748A discloses a high-temperature, wave-transmitting composite material composed of an organic-inorganic hybrid resin and a method for preparing the same. This hybrid resin exhibits superior heat resistance, with decomposition temperatures exceeding 500°C in both air and nitrogen, and a resin residual weight exceeding 70% after oxidizing in air at 500°C for one hour. Compared to existing inorganic resins, the quartz fiber-reinforced composite material prepared from this hybrid resin exhibits superior mechanical properties, with a room temperature flexural strength exceeding 300 MPa and a high-temperature flexural strength of 150 MPa at 500°C. The composite material also exhibits excellent dielectric properties from room temperature to 500°C, within the 1-12 GHz range, with a dielectric constant below 3.25 and a dielectric loss below 0.012. This composite material can meet the high-temperature, short-duration application requirements of missiles, rockets, and other aircraft, and has excellent application prospects in the field of high-wave resistance and transmission. However, its dielectric constant and dielectric loss still fall short of the requirements for high-performance radome materials. Summary of the Invention

[0004] The purpose of the present invention is to provide an organic silicon composite material with improved high-temperature wave transmission performance through in-situ oxygen release and carbon removal and a preparation method thereof, which has the characteristics of stable dielectric properties at high temperatures.

[0005] The object of the present invention can be achieved by the following technical solution: A method for preparing an organosilicon composite material with improved high-temperature wave transmission performance by in-situ oxygen release and carbon removal, comprising the following steps:

[0006] S1: Using a methyl silicone resin (i.e., a polymer compound with a silicon-oxygen bond (Si-O) as the main chain and a methyl group (CH3) as the side chain) as a precursor, a mixture of a benzene solvent and ethanol is selected as the solvent, a resin solution is prepared by mixing, and cerium octanoate and cerium acetylacetonate are mixed into the resin solution;

[0007] S2: Compounding the resin solution with the fiber preform through a vacuum impregnation process;

[0008] S3: performing a stepwise temperature curing treatment on the composite material after the vacuum impregnation process to obtain the organosilicon composite material.

[0009] The present invention obtains an organic silicon composite material with good dielectric properties through impregnation-curing.

[0010] In the present invention, the selection of methyl silicone resin as a precursor has significant advantages in dielectric properties. The cross-linked network formed after curing and the ceramic structure generated by high-temperature pyrolysis have a low dielectric constant (usually <3.5) and a low dielectric loss factor (stable at high frequencies), which are suitable for high-frequency electronic devices and insulating materials. At the same time, during high-temperature pyrolysis, methyl escapes in the form of small molecules (such as methane), and the carbon residue is low, which avoids the formation of conductive carbon black and ensures the high insulation properties of the composite material.

[0011] The cerium octanoate and acetylacetonate added to the resin solution can decompose into cerium oxide at high temperatures, releasing oxygen that combines with carbon ions produced by the decomposition of organic groups to form gas, which helps maintain the dielectric properties of the material. Furthermore, compared to directly adding cerium oxide, cerium octanoate and cerium acetate are more soluble in organic solutions. Furthermore, the cerium octanoate and cerium acetate added to the resin solution decompose into cerium oxide at high temperatures, which is distributed as nanoparticles in the composite material. Compared to directly adding cerium oxide particles, the cerium octanoate and cerium acetate added to the resin solution have a larger specific surface area, which is more conducive to in-situ oxygen release and the removal of free carbon / carbon compound bonds. The simultaneous addition of cerium acetylacetonate and cerium octanoate to the resin solution is more effective in inhibiting free carbon formation, reducing dielectric loss, and improving dielectric stability compared to adding cerium octanoate / cerium acetylacetonate alone. The synergistic effect of the two optimizes the material's microstructure, reduces defects and impurities, and further improves dielectric properties. Furthermore, the good chemical stability of the two helps maintain the material's dielectric properties in high-temperature environments.

[0012] Preferably, the methyl silicone resin in step S1 has the following structural formula:

[0013] [-O-Si(CH3)2-O-Si(CH3)2-] n

[0014] n is 100-10000.

[0015] Preferably, the benzene solvent in step S1 includes toluene and xylene.

[0016] Preferably, the mass ratio of toluene to ethanol in step S1 is (4-5):1.

[0017] Preferably, in step S1, cerium octoate and cerium acetylacetonate are mixed and added into the resin solution in a total mass fraction of 2 to 10%.

[0018] Further preferably, the mass ratio of the cerium octanoate salt to the cerium acetylacetonate salt is 1:(0.5-2).

[0019] Preferably, the vacuum impregnation process in step S1 includes:

[0020] Place the fiber preform into a mold (vacuum container), evacuate to 0.05MPa-0.1MPa, and maintain the vacuum state for a period of time to allow the resin solution to fully penetrate into the interior of the fiber preform.

[0021] Further preferably, in step S3, the mold after the vacuum impregnation process is placed in an oven for step temperature curing treatment, and then the cured composite material is taken out of the mold to obtain the organic silicon composite material with good dielectric properties.

[0022] Preferably, the stepwise temperature-varying curing process in step S3 includes:

[0023] The heating rate during the curing process is set to be no less than 1°C / min, and the maximum curing temperature is set to be no more than 160°C.

[0024] More preferably, the initial heating rate is set at 3-5°C / min, the temperature is raised to 80-100°C and kept warm for 2-3 hours, and the final heating rate is set at 1-3°C / min, the temperature is raised to 120-160°C and kept warm for 4-5 hours.

[0025] Preferably, the mass ratio of the resin solution to the fiber preform is (3-5):1.

[0026] Preferably, the fiber preform is selected from quartz fiber, alumina fiber, and silicon nitride fiber.

[0027] An organic silicon composite material with improved high-temperature wave transmission performance through in-situ oxygen release and carbon removal is prepared by the above-mentioned preparation method.

[0028] An application of the above-mentioned organosilicon composite material is to use the organosilicon composite material in a radar antenna cover.

[0029] Preferably, the organosilicon composite material is used for aerospace radar radomes and missile radar radomes.

[0030] The resin-based composite material prepared by the present invention can still maintain stable dielectric properties under high temperature conditions and can be applied to aerospace vehicle radar antenna covers and missile radar antenna covers.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The cerium octanoate and acetylacetonate added to the resin solution of the present invention can decompose into cerium oxide at high temperature, thereby releasing oxygen and combining with carbon ions produced by decomposition of organic groups to generate gas, which is beneficial to maintaining the dielectric properties of the material; in addition, compared with directly adding cerium salts, cerium octanoate and cerium acetate acetonate are more soluble in organic solutions; and the cerium octanoate and cerium acetate acetonate added to the resin solution decompose into cerium oxide at high temperature, which is distributed as nanoparticles in the composite material. Compared with directly added cerium oxide particles, it has a larger specific surface area, which is more conducive to the in-situ oxygen release function and the removal of free carbon / carbon compound binding. Adding cerium acetylacetonate and cerium octanoate to the resin solution at the same time can more effectively inhibit the formation of free carbon, reduce dielectric loss, and improve dielectric stability compared to adding cerium octanoate / cerium acetylacetonate alone. The synergistic effect of the two optimizes the material microstructure, reduces defects and impurities, and further improves dielectric properties. In addition, under high temperature conditions, the good chemical stability of the two helps maintain the dielectric properties of the material, thereby reducing interface reflection loss and improving material transmittance.

[0033] 2. The methyl silicone resin of the present invention has significant advantages in dielectric properties as a precursor. The cross-linked network formed after curing and the ceramic structure generated by high-temperature pyrolysis have a low dielectric constant (usually <3.5) and a low dielectric loss factor (stable at high frequencies), making it suitable for high-frequency electronic devices and insulating materials. At the same time, during high-temperature pyrolysis, the methyl group escapes in the form of small molecules (such as methane), and the carbon residue is low, which avoids the formation of conductive carbon black and ensures the high insulation properties of the composite material.

[0034] 3. By selecting a mixture of toluene and ethanol as the solvent, the present invention can effectively reduce the reflection of electromagnetic waves and energy loss in the material by optimizing dielectric properties (reducing dielectric constant and loss), improving material processability (enhancing solubility, dispersibility and regulating volatilization rate), and improving material density (reducing surface tension to reduce interface defects), while taking into account environmental protection (reducing benzene toxicity) and process adaptability.

[0035] 4. The dielectric constant of the present invention is less than 2.4 and the dielectric loss is less than 0.027 at 1000°C, which can meet the requirements of high-level antenna cover materials. DETAILED DESCRIPTION

[0036] The embodiments of the present invention are described in detail below. The following embodiments are implemented based on the technical solutions of the present invention, and provide detailed implementation methods and specific operating processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0037] A silicone composite material that improves high-temperature wave transmission performance through in-situ oxygen release and carbon removal, and a preparation method thereof. A methyl silicone resin (i.e., a polymer compound with a silicon-oxygen bond (Si-O) as the main chain and a methyl group (CH3) as the side chain) is selected as a precursor, and a mixture of toluene and ethanol is selected as a solvent. A resin solution is prepared by mixing, and cerium octanoate and cerium acetylacetonate are added to the resin solution in a certain proportion. The resin solution is compounded with a fiber preform through a vacuum impregnation process, and an organosilicon composite material with excellent dielectric properties is obtained through impregnation-curing. Compared with the prior art, the composite material of the present invention has the function of stable dielectric properties at high temperatures and can be used as a missile radar antenna cover material.

[0038] The following describes the details in conjunction with specific embodiments.

[0039] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0040] In the following examples and comparative examples, the methyl silicone resin has the following structural formula:

[0041] [-O-Si(CH3)2-O-Si(CH3)2-] n

[0042] n is 6000.

[0043] Example 1

[0044] Step 1: Using methyl silicone resin as a precursor, selecting toluene and ethanol mixed in a ratio of 4:1 as a solvent, and preparing a resin solution by mixing;

[0045] Step 2: The mass fraction of cerium octanoate and cerium acetylacetonate is set to 2%, and the mass ratio of cerium octanoate and cerium acetylacetonate is set to 1:1.

[0046] Step 3: Select a 2.5D quartz fiber preform as the reinforcement material.

[0047] Step 4: Place the quartz fiber preform in a vacuum container, evacuate to 0.05 MPa, and maintain the vacuum state for a period of time to allow the resin to fully penetrate into the interior of the quartz fiber preform.

[0048] Step 5: Place the vacuum impregnation mold in an oven for a step-by-step temperature curing process to obtain a silicone composite with excellent dielectric properties. Set the initial heating rate at 3°C / min to 80°C and hold for 2 hours. Finally, increase the temperature at a rate of 1°C / min to 120°C and hold for 4 hours.

[0049] Example 2

[0050] Step 1: Using methyl silicone resin as a precursor, a mixture of toluene and ethanol in a ratio of 5:1 was selected as a solvent, and a resin solution was prepared by mixing;

[0051] Step 2: The mass fraction of cerium octanoate and cerium acetylacetonate is set to 6%, and the mass ratio of cerium octanoate to cerium acetylacetonate is set to 1:0.5.

[0052] Step 3: Select an orthogonal triaxial quartz fiber preform as the reinforcement material.

[0053] Step 4: Place the quartz fiber preform into a vacuum container, evacuate to 0.1 MPa, and maintain the vacuum state for a period of time to allow the resin to fully penetrate into the interior of the quartz fiber preform.

[0054] Step 5: Place the vacuum impregnation mold in an oven for a step-by-step temperature curing process to obtain a silicone composite with excellent dielectric properties. Set the initial heating rate at 3°C / min to 90°C and hold for 2 hours. Finally, increase the temperature at a rate of 3°C / min to 140°C and hold for 4 hours.

[0055] Example 3

[0056] Step 1: Using methyl silicone resin as a precursor, selecting toluene and ethanol mixed in a ratio of 4:1 as a solvent, and preparing a resin solution by mixing;

[0057] Step 2: The mass fraction of cerium octanoate and cerium acetylacetonate is set to 10%, and the mass ratio of cerium octanoate to cerium acetylacetonate is set to 1:2.

[0058] Step 3: Select an alumina fiber preform as the reinforcement material.

[0059] Step 4: Place the quartz fiber preform in a vacuum container, evacuate to 0.05 MPa, and maintain the vacuum state for a period of time to allow the resin to fully penetrate into the interior of the quartz fiber preform.

[0060] Step 5: Place the vacuum impregnation mold in an oven for a step-by-step temperature curing process to obtain a silicone composite with excellent dielectric properties. Set the initial heating rate to 3°C / min, raise the temperature to 100°C and hold for 2 hours, and finally increase the temperature to 160°C at a rate of 3°C / min and hold for 4 hours.

[0061] Comparative Example 1

[0062] Step 1: Using methyl silicone resin as a precursor, selecting toluene and ethanol mixed in a ratio of 4:1 as a solvent, and preparing a resin solution by mixing;

[0063] Step 2: Select a 2.5D quartz fiber preform as the reinforcement material.

[0064] Step 3: Place the quartz fiber preform into a vacuum container, evacuate to 0.05 MPa, and maintain the vacuum state for a period of time to allow the resin to fully penetrate into the interior of the quartz fiber preform.

[0065] Step 4: Place the vacuum impregnation mold in an oven for a step-by-step temperature curing process to obtain a silicone composite with excellent dielectric properties. Set the initial heating rate at 3°C / min to 80°C and hold for 2 hours. Finally, increase the temperature at a rate of 1°C / min to 120°C and hold for 4 hours.

[0066] Comparative Example 2

[0067] Step 1: Using methyl silicone resin as a precursor, a mixture of toluene and ethanol in a ratio of 5:1 was selected as a solvent, and a resin solution was prepared by mixing;

[0068] Step 2: Set the mass fraction of cerium octoate to 2%.

[0069] Step 3: Select an orthogonal triaxial quartz fiber preform as the reinforcement material.

[0070] Step 4: Place the quartz fiber preform into a vacuum container, evacuate to 0.1 MPa, and maintain the vacuum state for a period of time to allow the resin to fully penetrate into the interior of the quartz fiber preform.

[0071] Step 5: Place the vacuum impregnation mold in an oven for a step-by-step temperature curing process to obtain a silicone composite with excellent dielectric properties. Set the initial heating rate at 3°C / min to 90°C and hold for 2 hours. Finally, increase the temperature at a rate of 3°C / min to 140°C and hold for 4 hours.

[0072] Comparative Example 3

[0073] Step 1: Using methyl silicone resin as a precursor, selecting toluene and ethanol mixed in a ratio of 4:1 as a solvent, and preparing a resin solution by mixing;

[0074] Step 2: Set the mass fraction of cerium oxide to 10%.

[0075] Step 3: Select an alumina fiber preform as the reinforcement material.

[0076] Step 4: Place the quartz fiber preform in a vacuum container, evacuate to 0.05 MPa, and maintain the vacuum state for a period of time to allow the resin to fully penetrate into the interior of the quartz fiber preform.

[0077] Step 5: Place the vacuum impregnation mold in an oven for a step-by-step temperature curing process to obtain a silicone composite with excellent dielectric properties. Set the initial heating rate to 3°C / min, raise the temperature to 100°C and hold for 2 hours, and finally increase the temperature to 160°C at a rate of 3°C / min and hold for 4 hours.

[0078] Table 1 summarizes the properties of the fiber-reinforced organosilicon composite materials obtained in Examples 1 to 3 and the resin-based composite materials obtained in Comparative Examples 1 to 3 after carbonization at 800°C. The dielectric constant was tested according to GBT 32361-2015, and the transmittance was tested according to GJB 7954-2012.

[0079] Table 1

[0080]

[0081] By comparing Examples 1, 2, and 3, it can be found that when the temperature reaches above the decomposition temperature of cerium octoate and cerium acetonate, as the content of cerium acetylacetonate and cerium octoate increases, the dielectric properties and wave transmittance of the material are significantly improved.

[0082] By comparing Example 1 and Comparative Example 1, it can be found that in the organic wave-transmitting material, the silicone resin solution with cerium acetylacetonate and cerium octoate added as the precursor has greatly improved the ability to maintain stable dielectric properties at high temperatures compared to the resin solution without cerium acetylacetonate and cerium octoate added.

[0083] By comparing Example 2 and Comparative Example 2, it can be found that in the organic wave-transmitting material, the silicone resin solution with cerium acetylacetonate and cerium octoate added as the precursor has greatly improved the ability to maintain stable dielectric properties at high temperatures compared to the resin solution with only a small amount of cerium octoate added.

[0084] By comparing Example 3 and Comparative Example 3, it can be found that in the organic wave-transmitting material, the silicone resin solution with cerium acetylacetonate and cerium octoate added as a precursor has greatly improved the ability to maintain stable dielectric properties at high temperatures compared to the resin solution with only an equal amount of cerium oxide added.

[0085] The material obtained by the present invention has the function of maintaining stable dielectric properties at high temperatures and has broad application prospects in aerospace radar antenna covers.

[0086] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A method for preparing an organosilicon composite material with improved high-temperature wave transmission performance by in-situ oxygen release and carbon removal, characterized in that: The following steps are involved: S1: using methyl silicone resin as a precursor and a mixture of toluene and ethanol as a solvent, a resin solution is prepared by mixing, and cerium octanoate and cerium acetylacetonate are mixed into the resin solution; S2: Compounding the resin solution with the fiber preform through a vacuum impregnation process; S3: performing a stepwise temperature curing treatment on the composite material after the vacuum impregnation process to obtain the organosilicon composite material.

2. The method for preparing an organosilicon composite material with improved high-temperature wave transmission performance by in-situ oxygen release and carbon removal according to claim 1, characterized in that: The mass ratio of toluene to ethanol in step S1 is (4-5):

1.

3. The method for preparing an organosilicon composite material with improved high-temperature wave transmission performance through in-situ oxygen release and carbon removal according to claim 1, characterized in that: Step S1: adding cerium octoate and cerium acetylacetonate in a total mass fraction of 2-10% into the resin solution.

4. The method for preparing an organosilicon composite material with improved high-temperature wave transmission performance through in-situ oxygen release and carbon removal according to claim 3, characterized in that: The mass ratio of the cerium octanoate salt to the cerium acetylacetonate salt is 1:(0.5-2).

5. The method for preparing an organosilicon composite material with improved high-temperature wave transmission performance through in-situ oxygen release and carbon removal according to claim 1, characterized in that: The vacuum impregnation process in step S1 includes: Place the fiber preform into the mold, evacuate to 0.05MPa-0.1MPa, and maintain the vacuum state for a period of time to allow the resin solution to fully penetrate into the interior of the fiber preform.

6. The method for preparing an organosilicon composite material with improved high-temperature wave transmission performance through in-situ oxygen release and carbon removal according to claim 5, characterized in that: In step S3, the mold after the vacuum impregnation process is placed in an oven for step-by-step temperature curing treatment, and then the cured composite material is taken out of the mold to obtain the organic silicon composite material.

7. The method for preparing an organosilicon composite material with improved high-temperature wave transmission performance through in-situ oxygen release and carbon removal according to claim 1, characterized in that: The stepwise temperature-changing curing process in step S3 includes: The heating rate during the curing process is set to be no less than 1°C / min, and the maximum curing temperature is set to be no more than 160°C.

8. The method for preparing an organosilicon composite material with improved high-temperature wave transmission performance through in-situ oxygen release and carbon removal according to claim 7, characterized in that: Set the initial heating rate to 3-5°C / min, heat to 80-100°C and keep warm for 2-3 hours, and the final heating rate to 1-3°C / min, heat to 120-160°C and keep warm for 4-5 hours.

9. The method for preparing an organosilicon composite material with improved high-temperature wave transmission performance through in-situ oxygen release and carbon removal according to claim 1, characterized in that: The mass ratio of the resin solution to the fiber preform is (3-5):1; The fiber preform is selected from quartz fiber, alumina fiber, and silicon nitride fiber.

10. An organic silicon composite material that improves high-temperature wave transmission performance by in-situ oxygen release and carbon removal, characterized in that: The preparation method according to any one of claims 1 to 9 is used.

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