Composite material for radome, high-power resistant radome and preparation method thereof

Abstract

The present invention discloses a composite material for radome, a high-power resistant radome and a preparation method thereof. The composite material comprises a plurality of skin layers and a foam core layer, the skin layers and the foam core layer are spaced from each other, and the inner and outer layers are skin layers; the skin layer is formed by compounding silicone resin and a plurality of layers of fiber cloth; the preparation method at least comprises the following steps: preparing a silicone resin composition, and compounding the silicone resin composition with the fiber cloth layer by layer; using the inner and outer layers as skin layers, and alternately laying in the middle in a manner that the skin layers and the foam core layer are spaced from each other to form a preform; heating and pressurizing the preform to cure to obtain a high-power resistant composite radome. The advantages are that the silicone resin material has a low dielectric constant and a low loss tangent, so the heat energy conversion rate is low, and due to its high heat resistance performance, it can withstand high-power electromagnetic waves more, avoiding the radome being burned through and damaged; at the same time, the compounding of silicone resin and multiple layers of fiber cloth improves the mechanical properties and working bandwidth of the radome.

Description

Technical Field

[0001] The present invention relates to the technical field of radomes, and particularly to a radome that can withstand higher-power electromagnetic wave irradiation and a preparation method thereof. Background Art

[0002] A radome is a component that covers the antenna of communication, telemetry, guidance, fire control, navigation and other systems. It is used to protect the antenna to work properly under various harsh environmental conditions. For airborne and missile-borne applications, it also needs to maintain the aerodynamic shape. Therefore, the radome should not only have good wave transmission performance and mechanical properties to resist tensile, compressive, bending, shearing, impact and vibration, but also have environmental adaptability such as acid resistance, high and low temperature resistance, humidity resistance, corrosion resistance, sand and dust resistance, etc.

[0003] For example, the patent document of the hybrid fiber radome with the application publication number of CN109494471A is composed of a C-shaped sandwich material including an inner skin, a foam core layer, a middle skin, a foam core layer and an outer skin. The inner skin and the outer skin contain a Kevlar fiber layer and a glass fiber layer, and the two fibers are laid in a way of interlayer hybridization. The middle skin is a pure glass fiber layer, and an isotropic and low-density foam core layer is used between the inner and middle skins and between the middle and outer skins.

[0004] With the development of electronic countermeasure technology, the electromagnetic interference power is getting larger and larger. In airborne equipment, the continuous wave transmission power of a single antenna can reach hundreds of watts or even thousands of watts. Since the airborne radome is very close to the transmitting antenna, high-power electromagnetic waves enter the radome with almost no attenuation in space, resulting in a very high power density inside the radome. At this time, if the wave transmission loss of the radome material is large and the heat conduction and heat resistance are poor, the electromagnetic waves will be converted into heat energy and gradually accumulate, making the surface temperature of the radome higher and higher, and finally causing the surface coating of the radome to be damaged, the radome to be yellowed by baking, or even to be blackened or burned through and scrapped.

[0005] Therefore, the high-power radome has become a research hotspot in this field. Scientists are seeking a material with high power resistance, high strength and good wave transmission performance to prepare the radome and actively investing in research and development.

[0006] For example, the patent document with the authorization publication number of CN102709703B discloses a manufacturing method of metamaterials and a radome made of the metamaterials prepared by this method. The special electromagnetic characteristics of the metamaterials of this invention are used to meet the high-power requirements of the product. This kind of radome material includes a dielectric substrate, and a plurality of mutually separated artificial microstructures are arranged on both surfaces of the dielectric substrate. Two polymer layers are respectively bonded to both surfaces of the dielectric substrate to cover the artificial microstructures on the corresponding surfaces, so as to form an integrated metamaterial.

[0007] As disclosed in the patent document with the authorization announcement number CN106129615B, a broadband wave-transparent double-layer composite ceramic radome and its preparation method are provided. The ceramic radome meets the power tolerance requirements of the product with the high-temperature resistance of inorganic materials. The profiling fabric of the radome is an integrated structure, which includes an inner layer and an outer layer. The inner layer is formed by alternately laying and stitching hollow quartz fiber cloth and hollow quartz fiber web, and the outer layer is formed by laying and stitching solid quartz fiber cloth. A diaphragm layer is laid between the inner layer and the outer layer; both the inner layer and the outer layer are compounded with a silicon oxide matrix.

[0008] As disclosed in the patent document with the authorization announcement number CN102931482B, a symmetric multi-layer dual-band radome structure and its preparation method are provided. The material of the skin dielectric layer is dense silicon nitride ceramic; the material of the transition dielectric layer is one of porous silicon nitride ceramic, porous boron nitride ceramic or ceramic matrix composite; the material of the intermediate dielectric layer is a resin-based lattice composite material layer. Similar to the aforementioned patent, the heat resistance of silicon nitride ceramic is also used to meet the power tolerance requirements of the product.

[0009] However, ceramic materials have inherent deficiencies in weight and bandwidth compared with organic polymer materials. While improving heat resistance, selecting polymer materials with low dielectric constant and low dielectric loss is the research and development direction of high-power-tolerant polymer radome products.

[0010] As disclosed in [Xia Wenqian, Han Yangjun, etc., Research on High-Power High-Wave-Transparent Materials, High-Tech Fibers and Applications, Vol.28, No.2, 2003.] literature, researchers prepared high-power-tolerant high-wave-transparent materials using natural rubber (TRR). As a non-polar rubber material, it usually has good wave-transparent properties. However, the material stiffness is an insurmountable obstacle. In radome products, if the deformation of the radome under load cannot be effectively controlled, it may damage internal devices such as antennas. In airborne or missile-borne equipment, it may also lose its aerodynamic shape due to the deformation of the radome, and in severe cases, it may lead to major accidents such as equipment damage and casualties.

[0011] [Tong Wenqing, Li Lei, Bai Yifeng, Selection of High-Temperature Composites and Their Application in High-Power Radar Radomes, Technology and Equipment, 9, 2019.] literature discloses that researchers believe that the combination of bismaleimide resin / S glass fiber is an ideal skin material for high-power-tolerant radomes. However, the experimental method used in the article avoids the material temperature rise caused by microwaves and only simply examines the heat resistance of the materials. Therefore, this conclusion still needs to be verified and discussed.

[0012] In addition, there are also studies on the application of metamaterials in high-power resistant radomes, such as [Wang Chu, Zhou Juehui, etc., Multiphysical Field Coupling Behavior of Metamaterials under High-Power Electromagnetic Wave Irradiation, Materials Review, Vol. 33, No. 21, 2019.] and left-handed materials [Li Zhenqiang, Zhang Xiaoping, etc., Experimental Study on High-Power Microwave Radome of X-Band Left-Handed Materials, High Power Laser and Particle Beams, Vol. 25, No. 6, 2013.]. However, it is estimated that it will still take some time for these studies to be put into practical use.

[0013] At present, high-power resistant radomes are mostly prepared from cyanate ester resin or polyimide (PI) resin. For example, the broadband millimeter-wave radome and its preparation method with the application publication number CN110571522A disclose a radome prepared from cyanate ester resin. The radome disclosed in this patent document is a C-type sandwich material, which from top to bottom is quartz fiber-reinforced cyanate ester resin, PMI foam, quartz fiber-reinforced cyanate ester resin, PMI foam, and quartz fiber-reinforced cyanate ester resin.

[0014] The main disadvantages of radomes prepared from cyanate ester resin are mainly the complex process and high processing temperature. The curing process of cyanate ester resin needs to go through three stages: pre-curing, curing, and post-curing. Taking E-type bisphenol cyanate ester resin (containing 0.02% dibutyltin dilaurate catalyst) as an example, the temperatures of the three stages need to reach 120°C, 200°C, and above 250°C respectively, and the entire curing time exceeds 10 hours. The molding process cycle is long and the energy consumption is high.

[0015] In addition, PI resin has a very high heat-resistant temperature, but it is easy to generate voids during the molding process, resulting in a low product yield. The biggest disadvantage lies in its high price, especially the high heat-resistant varieties. Summary of the Invention

[0016] On the premise of meeting the electrical and mechanical properties of the radome, the present invention increases the power capacity of the radome product, and provides a high-power resistant radome and its preparation method, so that the radome can withstand higher-power electromagnetic wave irradiation and will not be burned out.

[0017] The technical solution adopted by the present invention to solve the above technical problems is: the composite material for the radome is a laminated structure composed of several skin layers and several foam core layers. The inner and outer sides are skin layers, and the skin layers and foam core layers are alternately laminated in an alternating manner; the skin layer is composed of silicone resin and several layers of fiber cloth. The silicone resin enters the fiber gaps of each layer of fiber cloth and penetrates to both sides of each layer of fiber cloth. The silicone resin between each layer of fiber cloth and between the fiber cloth and the foam core layer tightly bonds each layer of material to form an integral structure.

[0018] A further preferred technical solution adopted by the present invention to solve the above technical problems is that the silicone resin is a composition of phenyl vinyl silicone resin and phenyl hydrogen-containing silicone resin.

[0019] A further preferred technical solution adopted by the present invention to solve the above technical problems is that the number of skin layers is 2 - 5 layers, and correspondingly, the number of foam core layers is 1 - 4 layers.

[0020] A further preferred technical solution adopted by the present invention to solve the above technical problems is that the fiber cloth is prepared from at least one of quartz fiber, D-glass fiber, S-glass fiber, and high-silica glass fiber, and the fiber cloth is a fabric or a unidirectional tape.

[0021] A further preferred technical solution adopted by the present invention to solve the above technical problems is that the mass fraction of the silicone resin in the skin is 25 - 50%.

[0022] A further preferred technical solution adopted by the present invention to solve the above technical problems is that in the phenyl vinyl silicone resin, the mass fraction ratio of phenyl to methyl is 100 / 0 - 30 / 70, and the mass fraction of vinyl is 1.0 - 8.0%; the hydrogen mass fraction of the phenyl hydrogen-containing silicone resin is 0.5 - 1.8%; the molar ratio of the silicon hydride group in the phenyl hydrogen-containing silicone resin to the silicon vinyl group in the phenyl vinyl silicone resin is 1.0 - 1.7.

[0023] A further preferred technical solution adopted by the present invention to solve the above technical problems is that the foam core layer is polymethacrylimide (PMI) foam with a density of 30 - 100 kg / m3.

[0024] The technical solution adopted by the present invention to solve the above technical problems is that the radome composite material is a multi-layer sandwich structure composed of several skin layers and foam core layers, and the inner and outer sides are skin layers, and the skin layers and foam core layers are alternately laminated in an alternating manner;

[0025] The skin layer is composed of a silicone resin and several layers of fiber cloths laminated layer by layer. The silicone resin enters the fiber gaps of each layer of fiber cloth and penetrates to both sides of each layer of fiber cloth. The silicone resin between each layer of fiber cloth and between the fiber cloth and the foam core layer tightly bonds each layer of material into an integral structure;

[0026] The foam core layer is PMI foam with a density of 50 - 110 kg / m3;

[0027] The silicone resin is a composition of phenyl vinyl silicone resin and phenyl hydrogen-containing silicone resin; the mass fraction of the silicone resin in the skin is 25 - 50%;

[0028] In the described phenylvinyl silicone resin, the mass fraction ratio of phenyl to methyl is 100 / 0 to 30 / 70, and the mass fraction of vinyl is 1.0 to 5.0%; the hydrogen mass fraction of the phenylhydrogen silicone resin is 0.8 to 1.5%, and the molar ratio of the silicon-hydrogen group in the phenylhydrogen silicone resin to the silicon-vinyl group in the phenylvinyl silicone resin is 1.2 to 1.5.

[0029] The technical solution adopted by the present invention to solve the above technical problems is: a high-power resistant radome, which is made of the composite material for radome described above.

[0030] The technical solution adopted by the present invention to solve the above technical problems is: the preparation method of the composite material for radome at least includes the following steps:

[0031] Prepare a silicone resin composition: the described silicone resin composition includes a silicone resin, a plasticizer, an inhibitor, and a curing agent;

[0032] Provide a number of fiber cloths, and layer-by-layer composite the silicone resin composition with the fibers;

[0033] Use the inner and outer two layers as the skin layers, and alternately lay layers in the way that the skin layers and the foam core layer are spaced from each other to form a preform;

[0034] Heat and press the preform until the preform is cured to form the composite material for radome.

[0035] A further preferred technical solution adopted by the present invention to solve the above technical problems is: the silicone resin composition and the fiber cloth are composite by a vacuum bag pressing hand lay-up molding process.

[0036] The technical solution adopted by the present invention to solve the above technical problems is: the preparation method of a high-power resistant radome, including the following steps:

[0037] Step 1, prepare a mold adapted to the contour of the radome body;

[0038] Step 2, prepare the above-mentioned fiber cloth and foam core layer, and perform surface treatment, and prepare a silicone resin composition;

[0039] Step 3, layer-by-layer lay the fiber cloth and layer-by-layer composite the silicone resin combination, and layer-by-layer composite the silicone resin composition with each layer of fiber cloth; the silicone resin composition infiltrates into each layer of stone fiber cloth, enters the fiber gaps of the fiber cloth and penetrates to both sides of each layer of fiber cloth;

[0040] Step 4, place the foam core layer on the uppermost layer of fiber cloth laid in Step 2, and the uppermost layer of fiber cloth and the silicone resin composition are in contact with the lower surface of the foam core layer at the same time;

[0041] Step 5, continue to layer-by-layer lay the fiber cloth and layer-by-layer or spray the silicone resin composition and then place the foam core layer;

[0042] Step Six: By analogy in the above manner, use the inner and outer layers as the skin layers, and alternately lay layers in the way that the skin layers and the foam core layer are spaced from each other, to complete the preparation of the preform;

[0043] Step Seven: Use the vacuum bag pressing method to evacuate the preform at a certain temperature, and the preform is cured and demolded;

[0044] Step Eight: Trim and polish the blank obtained in Step Seven to further process it into a high-power resistant radome.

[0045] Compared with the existing material system, the advantages of the present invention are that silicone resin has a low dielectric constant, a low loss tangent, a low heat energy conversion rate, and coupled with the high heat resistance of silicone resin, it can make it more resistant to high-power electromagnetic waves, thereby avoiding the radome being damaged or burned through by high-power electromagnetic waves; at the same time, the working bandwidth of the radome is adjusted by using the composite of silicone resin and multi-layer fiber cloth, and the mechanical properties of the radome are improved.

[0046] The silicone resin composition infiltrates into each layer of fiber cloth, enters the gaps between the fibers of the fiber cloth and penetrates to both sides of each layer of fiber cloth. The silicone resin located between the layers tightly bonds the materials of each layer into one body, reduces the interlayer defects, increases the overall strength and stiffness of the radome, and improves the mechanical properties of the radome. Description of the Drawings

[0047] The present invention will be further described in detail below in conjunction with the drawings and preferred embodiments. However, those skilled in the art will understand that these drawings are only drawn for the purpose of explaining the preferred embodiments and should not be used as a limitation on the scope of the present invention. In addition, unless otherwise specified, the drawings only schematically show the composition or structure of the described object and may include exaggerated displays, and the drawings are not necessarily drawn to scale.

[0048] Figure 1 It is a schematic structural diagram of the composite material for the radome of the A sandwich structure in Embodiment 1;

[0049] Figure 2 It is a flow chart for preparing the radome body in Embodiment 1;

[0050] Figure 3 It is a schematic structural diagram of the composite material for the radome of the C sandwich structure in Embodiment 2;

[0051] Figure 4 It is a flow chart for preparing the radome body in Embodiment 1;

[0052] Figure 5 It is a schematic structural diagram of the composite material for the radome of the seven-layer sandwich structure in Embodiment 3;

[0053] Figure 6 It is a flow chart for preparing the radome body in Embodiment 3. Specific Embodiment

[0054] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Those skilled in the art will appreciate that these descriptions are only descriptive and exemplary, and should not be construed as limiting the scope of protection of the present invention.

[0055] It should be noted that similar reference numerals denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it may not be further defined and explained in subsequent drawings.

[0056] Embodiment 1:

[0057] As Figure 1 shown, the composite material for the radome, which is used to make the radome body, includes an outer skin layer 1 located on the outside, an inner skin layer 2 located on the inside, and a foam core layer 3 sandwiched between the inner skin layer 2 and the outer skin layer 1. The composite material structure is an A sandwich, wherein both the inner skin layer 2 and the outer skin layer 1 are composed of a silicone resin 10 and several layers of fiber cloth 20.

[0058] In this embodiment, there are a total of 5 layers of fiber cloth 20 in the inner and outer skins. The silicone resin penetrates through the fiber gaps of the fiber cloth to both sides of each layer of the fiber cloth, so that the silicone resin wraps each fiber of the fiber, and further makes the silicone resin and the fiber combine into a whole, which further increases the overall strength and stiffness of the skin layer and improves the load-bearing capacity of the radome.

[0059] It should be noted that the silicone resin has a low dielectric constant, a low loss tangent, and can be used for a long time under the condition of +250 °C. Therefore, while having high wave permeability, it can be more resistant to high-power electromagnetic waves and more heat-resistant, so as to avoid the radome being roasted yellow, burned black, or burned through and scrapped. It should be noted that the coating is likely to still be burned out, but even if the coating is burned out, the body of the radome will not be burned through and scrapped.

[0060] Preferably, in this embodiment, the silicone resin is a composition of phenyl vinyl silicone resin and phenyl hydrogen silicone resin, the fiber cloth is quartz fiber, the foam core layer is PMI foam, and the density is 30 kg / m3. The mass fraction of the silicone resin in the skin is 35%.

[0061] The radome body containing the above composite material for the radome is prepared through the steps as Figure 2 shown:

[0062] I. Preparation work:

[0063] a. Prepare a mold that fits the contour of the radome's cover body;

[0064] b. Prepare quartz fiber cloth and PMI foam, and perform surface treatment.

[0065] c.. Prepare the silicone resin composition:

[0066] Design the formula according to the molar ratio of Si-H (silicon hydride group) in phenyl hydrogen-containing silicone resin to Si-Vi (silicon vinyl group) in phenyl vinyl silicone resin being 1.25;

[0067] Weigh 90 parts of phenyl vinyl silicone resin, where the mass fraction of vinyl is 1.2%; the mass fraction ratio of phenyl to methyl is 80 / 20;

[0068] Dissolve the above-mentioned phenyl vinyl silicone resin in 20 parts of vinyl silicone oil with a viscosity of 500 mPa·s as a plasticizer, and the mass content of silicon vinyl group is 0.8%;

[0069] After dissolving evenly, add 4.10 parts of phenyl hydrogen-containing silicone resin and 0.1 part of tackifier, where the mass content of hydrogen in the phenyl hydrogen-containing silicone resin is 1.3%.

[0070] After high-speed stirring evenly, weigh 0.001 part of hexynol as an inhibitor, and add 0.01 part of Pt curing agent with a Pt content of 800 ppm after stirring for 30 min.

[0071] Stir at room temperature for 1 h (rotation speed 300 rpm) to obtain the silicone resin composition.

[0072] II. Prepare a preform of the composite material by the hand lay-up molding process:

[0073] a. Lay 5 layers of quartz fiber cloth layer by layer in the mold and hand lay the above-mentioned silicone resin composition layer by layer to composite the silicone resin composition with the 5 layers of fiber cloth; the silicone resin composition infiltrates each layer of quartz fiber cloth and enters the fiber gaps of the fiber cloth and penetrates to both sides of each layer of quartz fiber cloth;

[0074] b. Place PMI foam on the topmost layer of the quartz fiber cloth laid above, and the quartz fiber cloth and the silicone resin composition are in contact with the lower surface of the PMI foam at the same time;

[0075] c. Continue to lay 5 layers of quartz fiber cloth layer by layer and hand lay the above-mentioned silicone resin composition layer by layer to complete the preparation of the preform.

[0076] III. Prepare a sandwich composite radome by vacuum bag pressing:

[0077] The above uncured preform and the mold are wrapped with the same airtight bag film, and vacuum is pumped at 180 °C for 3 hours, so that the surface of the preform bears pressure under the heated state and is cured to form a silicone resin composite power-resistant radome. The blank obtained by demolding is trimmed and polished and further processed to form a power-resistant radome.

[0078] It should be noted that after the molding process is carried out using a mold adapted to the radome body, the radome body itself is obtained after curing and molding. Only simple trimming and polishing are required, and no further processing is needed, thus simplifying the processing technology.

[0079] Curing reaction formula:

[0080]

[0081] At this time, it can be seen that the silicone resin located between the layers tightly bonds the layer materials together, reducing the interlayer defects, increasing the overall strength and stiffness of the radome, and enhancing the load-bearing capacity of the radome.

[0082] The sandwich composite prepared above is tested to confirm the effect:

[0083] I. Prepare a silicone resin PMI foam A sandwich flat plate for testing and a silicone resin fiber composite board with the same skin layer using the above preparation method;

[0084] a. The thickness of the inner skin layer and the outer skin layer is 0.48 mm, the thickness of the foam core layer is 6.54 mm, and the overall thickness of the specimen is 7.50 mm;

[0085] b. The dielectric constant of the skin layer is 3.22, and the loss tangent value is 0.012;

[0086] The dielectric constant of the foam core layer is 1.05, and the loss tangent value is 0.0009;

[0087] d. The tensile strength of the silicone resin fiber composite board is 325 MPa, the tensile modulus is 9.4 GPa, and the flexural strength is 187 MPa. It can meet the mechanical property requirements of the radome skin layer.

[0088] II. Prepare a comparative sample, and through comparative testing, the power-resistant performance of the composite material is tested. The dimensions of each part of the honeycomb sandwich panel in the comparative sample are the same as those of the silicone resin / PMI foam test panel. The temperature rise value in the table is equal to the difference between the highest temperature on the surface of the sample during the test and the temperature on the surface of the sample before the test.

[0089] specimen electromagnetic wave temperature rise silicone resin PMI foam A sandwich <![CDATA[15GHz, 14.5W / cm 2 > 54℃ vinyl ester resin PMI foam A sandwich <![CDATA[15GHz, 13W / cm 2 > 93℃ epoxy resin aramid paper honeycomb A sandwich (bonded with epoxy film) <![CDATA[17GHz, 13W / cm 2 > 185℃ cyanate ester resin aramid paper honeycomb A sandwich (bonded with epoxy film) <![CDATA[17GHz, 14.5W / cm 2 > 97℃ bismaleimide resin aramid paper honeycomb A sandwich (bonded with epoxy film) <![CDATA[17GHz, 14.5W / cm 2 > 120℃

[0090] Example two:

[0091] As Figure 3As shown, the composite material for radome includes, from outside to inside, a first skin layer 1', a first foam core layer 4', a second skin layer 2', a second foam core layer 5', and a third skin layer 3'. The structure of this composite material is a C sandwich. Each skin layer is composed of a silicone resin 10' and several layers of fiber cloth 20' laminated together. Each foam core layer is a PMI foam.

[0092] In this embodiment, each skin layer contains a total of 3 layers of fiber cloth 20'. The fiber cloth is a fabric made of a blend of S glass fiber and high silica glass fiber. The silicone resin penetrates through the fiber gaps of the fiber cloth to both sides of each layer of the fiber cloth, so that the silicone resin wraps each fiber, and then the silicone resin and the fiber are combined into a whole, which further increases the overall strength and stiffness of the skin layer and improves the load-bearing capacity of the radome.

[0093] It should be noted that the silicone resin has a low dielectric constant, a low loss tangent, and can be used for a long time under the condition of +250°C. Therefore, while having high wave transmission performance, it can be more resistant to high-power electromagnetic waves, with a low heat conversion rate, thereby reducing the damage of the radome coating and the yellowing of the radome body, and avoiding the radome being burned black or burned through and scrapped.

[0094] Preferably, in this embodiment, the silicone resin is a composition of phenyl vinyl silicone resin and phenyl hydrogen silicone resin. The density of the foam core layer is 80 kg / m3. The mass fraction of the silicone resin in the skin is 45%.

[0095] The radome body containing the above composite material for radome is prepared through the steps as Figure 4 shown:

[0096] I. Preparation operations:

[0097] a. Prepare a mold adapted to the contour of the radome body;

[0098] b. Prepare the above fabric fiber cloth and PMI foam, and perform surface treatment.

[0099] c.. Prepare the silicone resin composition:

[0100] Design the formula according to the molar ratio of Si-H (silicon hydride group) in phenyl hydrogen silicone resin / Si-Vi (silicon vinyl group) in phenyl vinyl silicone resin being 1.05;

[0101] Weigh 70 parts of phenyl vinyl silicone resin, where the mass fraction of vinyl is 1.2%; the mass fraction ratio of phenyl to methyl is 90 / 10;

[0102] Dissolve the above phenyl vinyl silicone resin in 30 parts of vinyl silicone oil with a viscosity of 8000 mPa·s as a plasticizer, and the mass content of silicon vinyl group is 1.2%;

[0103] After uniform dissolution, 4.1 parts of phenyl hydrogen-containing silicone resin and 0.05 part of tackifier are added, and the mass content of hydrogen in the phenyl hydrogen-containing silicone resin is 0.8%.

[0104] After uniformly stirring at high speed, 0.1 part of hexynol is weighed, and after stirring for 30 min, 0.001 part of Pt curing agent with a Pt content of 3000 ppm is added.

[0105] Stir at room temperature for 1 h (rotation speed 300 rpm) to obtain a silicone resin composition.

[0106] IV. Preparation of a preform of a composite material by a spraying process

[0107] a. Lay 3 layers of fabric fiber cloth layer by layer in a mold and spray the above silicone resin composition layer by layer, and laminate the silicone resin composition with 5 layers of fabric fiber cloth layer by layer; the silicone resin composition infiltrates each layer of fabric fiber cloth, enters the fiber gaps of the fabric fiber cloth, and penetrates to both sides of each layer of fabric fiber cloth.

[0108] b. Place PMI foam on the topmost layer of the fabric fiber cloth laid above, and the fabric fiber cloth and the silicone resin composition are in contact with the lower surface of the PMI foam at the same time.

[0109] c. Continue to lay 3 layers of fabric fiber cloth layer by layer and spray the above silicone resin composition layer by layer, and then place PMI foam.

[0110] d. By analogy in the above manner, complete the preparation of the preform in the form of skin-foam-skin-foam-skin-foam-skin.

[0111] V. Preparation of a composite material by vacuum bag pressing:

[0112] Wrap the above uncured preform and the mold with the same airtight bag film, and under vacuum bag pressing, carry out curing at 140 °C × 1 h + 180 °C × 2.5 h, so that the preform bears pressure in the heated state, so that the preform cures into a silicone resin power-resistant radome. Trim and polish the blank obtained by demolding to further process it into a power-resistant radome.

[0113] Curing reaction formula:

[0114]

[0115] Adopt the C sandwich radome wall structure. Compared with the A sandwich, since an additional layer of skin and an additional layer of foam are added, the stiffness and strength of the radome are increased, and the bandwidth of the operating frequency is improved.

[0116] Example III:

[0117] As Figure 5As shown, the radome uses a seven-layer composite material, including 4 skin layers 1" and 3 foam core layers 2". The skin layers 1" and the foam core layers 2" are laminated at intervals, and the outermost two layers are skin layers 1". The composite material structure is a seven-layer sandwich. Each skin layer is composed of silicone resin 10" and several layers of fiber cloth 20" compounded together. Each foam core layer is PMI foam.

[0118] In this embodiment, there are a total of 5 layers of fiber cloth 20", and the fiber cloth is a unidirectional tape using quartz fiber, D-glass fiber, and S-glass fiber. The silicone resin penetrates through the fiber gaps of each fiber cloth to both sides of each layer of fiber cloth, so that the silicone resin wraps each fiber, and then the silicone resin and the fiber are combined into a whole, further increasing the overall strength and stiffness of the skin layer and improving the load-bearing capacity of the radome.

[0119] It should be noted that the silicone resin has a low dielectric constant, a low loss tangent, and can be used for a long time under the condition of +250 °C. Therefore, while having high wave transparency, it can be more resistant to high-power electromagnetic waves and more heat-resistant, thereby reducing the damage of the radome coating and the radome being roasted yellow, and avoiding the radome being burned black or burned through and scrapped.

[0120] Preferably, in this embodiment, the silicone resin is a composition of phenyl vinyl silicone resin and phenyl hydrogen-containing silicone resin. The density of the foam core layer is 100 kg / m3. The mass fraction of the silicone resin in the skin is 30%.

[0121] The radome housing containing the above-mentioned composite material for the radome is prepared through the steps as Figure 6 shown:

[0122] I. Preparation work:

[0123] a. Prepare a mold adapted to the contour of the radome housing;

[0124] b. Prepare the above-mentioned fiber cloth and PMI foam and perform surface treatment.

[0125] c.. Prepare the silicone resin composition:

[0126] Design the formula according to the molar ratio of Si-H (silicon hydride group) in phenyl hydrogen-containing silicone resin / Si-Vi (silicon vinyl group) in phenyl vinyl silicone resin being 1.10;

[0127] Weigh 80 parts of phenyl vinyl silicone resin, where the mass fraction of vinyl is 2.0%; the mass fraction ratio of phenyl to methyl is 100 / 0;

[0128] Dissolve the above-mentioned phenyl vinyl silicone resin into 50 parts of vinyl silicone oil with a viscosity of 3000 mPa.s as a plasticizer, and the mass content of silicon vinyl group is 3.0%;

[0129] After uniform dissolution, 3.7 parts of phenyl hydrogen-containing silicone resin and 0.1 part of tackifier are added, and the mass content of hydrogen in the phenyl hydrogen-containing silicone resin is 1.8%.

[0130] After uniformly stirring at high speed, 0.1 part of hexynol is weighed, and after stirring for 30 min, 0.001 part of Pt curing agent with a Pt content of 1500 ppm is added.

[0131] Stir at room temperature for 1 h (rotation speed 300 rpm) to obtain a silicone resin composition.

[0132] VI. Preparation of a preform of the composite material by an impregnation process:

[0133] a. Lay 5 layers of fiber cloth impregnated with the above silicone resin composition layer by layer in the mold, and the silicone resin composition is laminated with the 5 layers of fabric fiber cloth layer by layer; the silicone resin composition enters the fiber gaps of the fabric fiber cloth and penetrates to both sides of each layer of fabric fiber cloth.

[0134] b. Place PMI foam on the uppermost layer of the fiber cloth laid above, and the fabric fiber cloth and the silicone resin composition are simultaneously in contact with the lower surface of the PMI foam.

[0135] c. Continue to lay 5 layers of fiber cloth impregnated with the above silicone resin composition layer by layer and then place PMI foam.

[0136] d. By analogy in the above manner, the inner and outer two layers are used as the skin layers, and the intermediate layers are alternately laminated in a manner of alternating skin layers and foam core layers to complete the preparation of the preform.

[0137] VII. Preparation of the composite material by vacuum bag pressing:

[0138] The above uncured preform and the mold are wrapped with the same airtight bag film, and under vacuum bag pressing, it is cured at 120 °C × 1 h + 140 °C × 1 h + 180 °C × 2.5 h, so that the surface of the preform bears pressure under the heated state, and is cured to form a silicone resin high-power composite radome. The blank obtained by demolding is trimmed and polished for further processing to form a high-power radome.

[0139] It should be noted that the above three embodiments are only the preferred modes among many embodiments. The composite material can also be a multi-layer structure such as a 9-layer sandwich.

[0140] The layering superposition of the above fiber cloth for reinforcement has certain angular requirements according to specific product designs. Specifically, it can include one of quartz fiber, D-glass fiber, S-glass fiber, and high-silica glass fiber, or a fabric and unidirectional tape made of two or more of them used in combination / blended. Other foam materials can also be selected for the foam core layer, and PMI foam is the best.

[0141] The mass fraction of silicone resin in the skin is 25 to 50%, preferably 35 to 45%; the density of PMI foam is 30 to 100 kg / m3, preferably 50 to 80 kg / m3.

[0142] In the selection of silicone resin, the mass fraction ratio of phenyl to methyl in phenyl vinyl silicone resin is 100 / 0 to 30 / 70, preferably 100 / 0 to 80 / 20. The mass fraction of vinyl is 1.0 to 8.0%, preferably 1.0 to 5.0%. The hydrogen mass fraction of phenyl hydrogen-containing silicone resin is 0.5 to 1.8%, preferably 0.8 to 1.5%.

[0143] The molar ratio of silicon hydride group in phenyl hydrogen-containing silicone resin to silicon vinyl group in phenyl vinyl silicone resin is 1.0 to 1.7, preferably 1.2 to 1.5.

[0144] The plasticizer is vinyl silicone oil, and the dosage is 0 to 20%. The mass fraction of silicon vinyl is 0.8 to 5.0%, preferably 0.8 to 1.2%. The curing agent is Pt curing agent, and the Pt content is 200 to 3000 ppm, preferably 800 to 1500 ppm.

[0145] The above has introduced in detail the silicone resin power-resistant radome material, structure and preparation method provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the present invention and its core idea. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a high-power radome, characterized in that It includes the following steps: Step 1: Prepare a mold adapted to the contour of the radome cover; Step 2: Prepare fiber cloth and foam core layer, perform surface treatment, and formulate a silicone resin composition; The fiber cloth is prepared from at least one of quartz fiber, D-glass fiber, S-glass fiber, and high-silica glass fiber, and the fiber cloth is a fabric or a unidirectional tape; The silicone resin composition includes silicone resin, plasticizer, and curing agent. The silicone resin is a composition of phenyl vinyl silicone resin and phenyl hydrogen-containing silicone resin; in the phenyl vinyl silicone resin, the mass fraction ratio of phenyl to methyl is 100:0 to 30:70, and the mass fraction of vinyl is 1.0 to 8.0%; the hydrogen mass fraction of the phenyl hydrogen-containing silicone resin is 0.5 to 1.8%, and the molar ratio of the silicon hydride group in the phenyl hydrogen-containing silicone resin to the silicon vinyl group in the phenyl vinyl silicone resin is 1.0 to 1.7; Step 3: Layer by layer lay the fiber cloth and layer by layer compound the silicone resin composition, and compound the silicone resin composition and each layer of fiber cloth through a vacuum bag pressing hand lay-up process to form a skin layer layer by layer; the silicone resin composition infiltrates each layer of fiber cloth, enters the fiber gaps of the fiber cloth, and penetrates to both sides of each layer of fiber cloth; the mass fraction of the silicone resin in the skin layer is 25 to 50%; Step 4: Place the foam core layer on the topmost layer of fiber cloth laid in Step 2, and the topmost layer of fiber cloth and the silicone resin composition simultaneously contact the lower surface of the foam core layer; Step 5: Continue to layer by layer lay the fiber cloth and layer by layer spray the silicone resin composition and then place the foam core layer; or continue to layer by layer lay the fiber cloth impregnated in the above silicone resin composition and then place the foam core layer; Step 6: Use the inner and outer two layers as the skin layer, and alternately lay the layers in the middle in a way that the skin layer and the foam core layer are spaced from each other to complete the preparation of the preform; Step 7: Use the vacuum bag pressing method to evacuate the preform at a certain temperature, and the preform is cured and demolded; Step 8: Trim and polish the blank obtained in Step 7 for further processing to form a high-power radome.

2. The preparation method of the power-resistant radome according to claim 1, characterized in that It includes the following steps: The plasticizer is vinyl silicone oil, with a dosage of 0 to 20%, the mass fraction of silicon vinyl is 0.8 to 5.0%, and the curing agent is Pt curing agent, with a Pt content of 200 to 3000 ppm.

3. Power-resistant radome, characterized in that Prepared by the method according to any one of claims 1-2, the high-power radome includes a sandwich structure composed of several skin layers and foam core layers, with the inner and outer sides being skin layers, and the layers in the middle are alternately laid in a way that the skin layer and the foam core layer are spaced from each other; the silicone resin between each layer of fiber cloth in the skin layer and the silicone resin between the fiber cloth and the foam core layer tightly bond each layer of materials into an integral structure.

4. The power-resistant radome according to claim 3, characterized in that The number of the skin layers is 2-5, and correspondingly, the number of the foam core layers is 1-4.

5. The power-resistant radome according to claim 3, characterized in that The described foam core layer is PMI foam with a density of 30 to 110 kg / m 3 .

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