A wave-absorbing composite material, an environmental member for radar, a radar, and a production method

Abstract

The application relates to a wave-absorbing composite material, an environmental part for a radar, a radar and a preparation method, which comprises, in terms of mass fraction, 25-35% graphene modified basalt fibers, 5-10% rare earth oxide modified carbon nanotubes and 55-70% nylon PA11. The wave-absorbing composite material is prepared by adopting a nylon PA11 bio-based resin as a base material and adopting graphene modified basalt fibers and rare earth oxide modified carbon nanotubes for modification, and the wave-absorbing composite material has good wave-absorbing performance for 77GHZ millimeter waves and waves of other frequency bands, effectively improves a signal-to-noise ratio, and avoids occurrence of false positives and false negatives. Through experiments, a 2mm-thick radar support is subjected to a 77Ghz millimeter wave electromagnetic loss test by using a QAR method, the transmission loss is greater than or equal to 14dB, the reflection loss is greater than or equal to 6dB, and the wave-absorbing parameter indexes of the millimeter wave radar support are completely met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of materials, in particular to a wave-absorbing composite material, a radar environmental component, a radar and a preparation method. BACKGROUND

[0002] Millimeter waves can be widely used in military radar systems, radio astronomy and space, automotive radar, medical applications of millimeter wave imaging and short-range wireless high-speed transmission and other fields. In order to solve the problem of millimeter wave electromagnetic wave radiation interference and electromagnetic pollution, it is of great significance to use absorbing materials to convert electromagnetic wave energy into other forms of energy to suppress electromagnetic wave radiation and interference, which has wide application prospects in military and civilian fields.

[0003] Some related technologies use double-layer wave-absorbing composite materials. The first layer of composite material is a composite material of iron-based rare earth intermetallic compound magnetic powder and a high molecular adhesive, and the second layer of composite material is a composite material of carbon material and a high molecular adhesive. The typical formula of the first layer is a composite material of 55wt% Y2Fe14Mn3 and polypropylene, and the second layer is composed of 6wt% carbon black and polypropylene as a binder, and its absorption peak at 26.5-40GHz is-20dB. The scheme has a large amount of magnetic powder filling. On the one hand, the forming performance is poor, the density is large, and it also has a bad influence on the mechanical properties, and it cannot be well adapted to the mass production mold of automobile parts. On the other hand, the related formula has poor electromagnetic shielding and absorbing effect in the 24GHz and 77GHz wave bands used in automobiles, and the reflection loss rapidly decays to less than-10dB.

[0004] Some other related technologies describe a super-structure millimeter wave absorbing sheet and its application. The super-structure millimeter wave absorbing sheet is composed of an absorbent and a hollow wave-absorbing super-structure, wherein the structural unit of the wave-absorbing super-structure is a coaxial open ring hollow pattern with a size of 7-13mm. The super-structure material has a significant wide-band light-weight microwave absorption effect: in the frequency range of 30-100GHz, the effective bandwidth less than-10dB is 5.25-41.03GHz. However, the main disadvantage of the super-structure material is that the pattern of the wave-absorbing material needs to be formed or attached, which is relatively complex and cannot be well adapted to the batch production of vehicle radar environmental components, and is only suitable for making small batches of exhibits or purposes. SUMMARY

[0005] The embodiments of the present application provide a wave-absorbing composite material, a radar environmental component, a radar and a preparation method, which have good wave-absorbing performance for 77GHZ millimeter waves and other frequency bands, effectively improve the signal-to-noise ratio, and avoid false positives and false negatives.

[0006] In a first aspect, a wave-absorbing composite material is provided, which comprises, in terms of mass fraction:

[0007] 25% to 35% graphene modified basalt fiber, 5% to 10% rare earth oxide modified carbon nanotube, and 55% to 70% nylon PA11.

[0008] In some embodiments, the particle size of the graphene is 500 nm to 1000 nm;

[0009] In some embodiments, the length of the graphene modified basalt fiber is 1 to 25 mm;

[0010] In some embodiments, the rare earth oxide is in the form of particles with a particle size of 3 to 20 nm;

[0011] In some embodiments, the rare earth includes one or more of samarium (Sm), erbium (Er), and europium (Eu).

[0012] In a second aspect, a method for preparing the wave-absorbing composite material as described above is provided, which includes:

[0013] 25% to 35% graphene modified basalt fiber, 5% to 10% rare earth oxide modified carbon nanotube, and 55% to 70% nylon PA11 are first stirred and mixed uniformly, and then melt-blended and granulated at 240°C to 260°C to obtain the wave-absorbing composite material.

[0014] In some embodiments, the method for preparing the graphene modified basalt fiber includes the following steps:

[0015] The basalt fiber is placed in an oxygen-enriched air atmosphere for first heat treatment;

[0016] An aqueous solution of graphene oxide is coated on the basalt fiber after the first heat treatment, and then second heat treatment is performed under inert gas protection;

[0017] The basalt fiber after the second heat treatment is vacuum impregnated in polydimethylsiloxane containing 1% to 3% organic peroxide curing agent and then cured to obtain the graphene modified basalt fiber.

[0018] In some embodiments, the volume fraction of oxygen in the oxygen-enriched air is 25% to 30%;

[0019] In some embodiments, the first heat treatment includes first treating at 480°C to 520°C for 50 min to 60 min, then increasing the temperature to 580°C to 600°C for 20 min to 30 min, and then increasing the temperature to 680°C to 700°C for 20 min to 30 min, and then naturally cooling, cleaning, and drying;

[0020] In some embodiments, the concentration of the aqueous solution of graphene oxide is 0.5 to 0.7 mg / ml;

[0021] And / or, the second heat treatment includes: treating at 650-700℃ for 10-20min, and then increasing the temperature by 50℃ to 700-750℃ for 5-15min;

[0022] And / or, the soaking time is 10-15min;

[0023] And / or, the curing temperature is 95-100℃, and the curing time is 50-60min;

[0024] And / or, the organic peroxide curing agent is dibutyl phthalate DBP or benzoyl peroxide BPO.

[0025] In some embodiments, the method for preparing the rare earth oxide modified carbon nanotube includes the following steps:

[0026] The rare earth oxide and the carbon nanotube are added into concentrated nitric acid, and then separated after refluxing;

[0027] The separated product is subjected to a third heat treatment under inert gas protection to obtain the rare earth oxide modified carbon nanotube.

[0028] In some embodiments, the mass ratio of the rare earth oxide to the carbon nanotube is 1:1;

[0029] And / or, the rare earth oxide includes Er2O3 and Eu2O3, and the mass ratio of Er2O3 to Eu2O3 is 3-2:1;

[0030] And / or, the rare earth oxide includes samarium Sm2O3, Er2O3 and Eu2O3, and the mass ratio of Sm2O3 to Er2O3 and Eu2O3 is 1:(1-2):1;

[0031] And / or, the concentration of the concentrated nitric acid is 70%-75%;

[0032] And / or, the oscillation dispersion is also performed by ultrasonic wave before refluxing;

[0033] And / or, the refluxing temperature is 90-95℃, and the time is 24-36h;

[0034] And / or, after the separation, the product is washed to neutral with deionized water and dried before the third heat treatment;

[0035] And / or, the inert gas is one or more of helium and neon;

[0036] And / or, the third heat treatment includes: first treating at 400-450℃ for 60-80min, then treating at 450-500℃ for 50-60min, and finally treating at 500-520℃ for 50-60min and then naturally cooling to room temperature.

[0037] In a third aspect, there is provided an environmental member for radar, wherein the material of the environmental member is the wave-absorbing composite material as described above.

[0038] Alternatively, the material of the environmental member is the wave-absorbing composite material prepared by the preparation method of the wave-absorbing composite material as described above.

[0039] In some embodiments, the surface of the environmental member is formed with a raised texture.

[0040] In some embodiments, the raised texture is in a honeycomb shape or a wedge shape.

[0041] In a fourth aspect, there is provided a preparation method of the environmental member for radar as described above, comprising:

[0042] injecting and molding the wave-absorbing composite material by an injection molding machine;

[0043] Alternatively, printing and molding the wave-absorbing composite material by a 3D printer.

[0044] In a fifth aspect, there is provided a radar comprising the environmental member for radar as described above, and a radar wave-transparent sheet window, wherein the environmental member further has a window, and the radar wave-transparent sheet window is in the window of the environmental member.

[0045] In some embodiments, the radar wave-transparent sheet window comprises a visible light wave band transparent module, a 77GHZ wave band transparent module, and a laser wave band transparent module, and the visible light wave band transparent module, the 77GHZ wave band transparent module, and the laser wave band transparent module are connected side by side in a designed order.

[0046] The radar wave-transparent sheet window is movably arranged on the environmental member, so that the visible light wave band transparent module, the 77GHZ wave band transparent module, and the laser wave band transparent module are selectively switched into the window.

[0047] In some embodiments, the designed order is: the visible light wave band transparent module, the 77GHZ wave band transparent module, and the laser wave band transparent module; or the visible light wave band transparent module, the 77GHZ wave band transparent module, and the laser wave band transparent module; or the 77GHZ wave band transparent module, the visible light wave band transparent module, and the laser wave band transparent module; or the 77GHZ wave band transparent module, the laser wave band transparent module, and the visible light wave band transparent module.

[0048] In some embodiments, the material of the visible light wave band transparent module comprises at least one of an optical-grade glass lens and a light-guiding-grade polycarbonate (PC) material.

[0049] In some embodiments, the material of the 77GHZ wave band transparent module includes at least one of polycarbonate PC, glass fiber modified material of polycarbonate PC, polybutylene terephthalate PBT and glass fiber modified material of polybutylene terephthalate PBT.

[0050] In some embodiments, the material of the laser wave band transparent module includes at least one of polycarbonate PC, polybutylene terephthalate PBT and polycarbonate PC containing a mass fraction of 0.5% to 1% black azo pigment color master modifier.

[0051] In some embodiments, the black azo pigment color master modifier includes azo red, azo yellow and azo blue, and the mass ratio of azo red: azo yellow: azo blue is 1:1.2-1.5:1.

[0052] The technical solutions provided by the application have the following beneficial effects:

[0053] The application provides a wave-absorbing composite material, an environmental part for a radar, a radar and a preparation method. The application uses nylon PA11 bio-based resin as a base material, and uses graphene modified basalt fiber and rare earth oxide modified carbon nanotube for modification. The obtained wave-absorbing composite material has good wave-absorbing performance for 77GHZ millimeter waves and waves of other frequency bands, effectively improves the signal-to-noise ratio, and avoids false positives and false negatives. According to experiments, a 2mm-thick radar support is subjected to 77Ghz millimeter wave electromagnetic loss testing by using a QAR method, the transmission loss is greater than or equal to 14dB, and the reflection loss is greater than or equal to 6dB, which fully meets the wave-absorbing parameter indexes of the millimeter wave radar support.

[0054] The environmental part can be prepared by using conventional injection molding and 3D printing, which is beneficial to batch production of products.

[0055] The radar wave-transparent sheet window uses three modules of window to be connected with each other, and is respectively for a visible light wave band, a 77GHZ millimeter wave band and a laser wave band. When the wave band function is switched, the corresponding window can be switched to the corresponding position. The function is more flexible, the multi-mode adaptation scene switching is realized, and the product is more competitive. For example, the infrared night vision mode, the laser detection mode and the millimeter wave detection mode all have good product performance. The window is modularly produced and matched. According to the configuration needs, the types and quantities of the matched products are selected, and the actual production is more easy. BRIEF DESCRIPTION OF DRAWINGS

[0056] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0057] Figure 1 A schematic diagram of the raised texture on the environment piece provided by the embodiment of the present application;

[0058] Figure 2 A schematic diagram of the mold surface hole provided by the embodiment of the present application. DETAILED DESCRIPTION

[0059] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of 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 part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0060] The embodiment of the present application provides a wave-absorbing composite material, which comprises 25-35% graphene modified basalt fiber, 5-10% rare earth oxide modified carbon nanotube and 55-70% nylon PA11 in terms of mass fraction.

[0061] The present application adopts nylon PA11 bio-based resin as the base material, and adopts graphene modified basalt fiber and rare earth oxide modified carbon nanotube for modification, so that the obtained wave-absorbing composite material has good wave-absorbing performance for 77GHZ millimeter waves and other frequency bands, effectively improves the signal-to-noise ratio, and avoids the occurrence of false positives and false negatives.

[0062] In the graphene modified basalt fiber, the particle size of the graphene used is 500-1000nm, and the purity of the graphene is >99wt%.

[0063] The size of the graphene modified basalt fiber can be processed according to subsequent needs, such as processing the size of the graphene modified basalt fiber to 1-25mm. Generally, the length of the short graphene modified basalt fiber is 1-5mm, and the length of the long graphene modified basalt fiber is 6-25mm.

[0064] In the rare earth oxide modified carbon nanotube, the rare earth oxide used is in the form of particles, such as an elliptical shape and the like, and the particle size is 3-20nm, which is equivalent to or slightly smaller than the inner diameter of the carbon nanotube, so that the rare earth oxide is filled in the carbon nanotube by using a liquid-phase wet chemical filling method.

[0065] The typical size of the carbon nanotube is tens of nanometers in diameter and micrometers in length.

[0066] The rare earths are one or more of samarium (Sm), erbium (Er) and europium (Eu), preferably, if one is used, erbium (Er) is used, if two are used, erbium (Er) and one of erbium (Er) and europium (Eu) are used, such as the rare earths are erbium (Er) and europium (Eu), at which time the rare earth oxide is a mixed particle of Er2O3 and Eu2O3, and further such as the rare earths are samarium (Sm), erbium (Er) and europium (Eu), at which time the rare earth oxide is samarium (Sm2O3), erbium (Er2O3) and europium (Eu2O3).

[0067] The complex system using two kinds of rare earths can better adapt to the frequency range of millimeter waves (the frequency width 72-80 GHz used by vehicles).

[0068] In order to obtain the above-mentioned wave-absorbing composite material, the application further provides a preparation method of the wave-absorbing composite material, which comprises the following steps: stirring and mixing 25%-35% graphene modified basalt fibers, 5%-10% rare earth oxide modified carbon nanotubes and 55%-70% nylon PA11 uniformly, and then performing melt blending and granulation under the condition of 240-260 DEG C to obtain the wave-absorbing composite material. The preparation method provided by the application is simple to operate and does not need to use relatively complex instruments.

[0069] Preferably, the melt blending temperature is 260 DEG C.

[0070] In order to obtain the graphene modified basalt fiber, the application further provides a preparation method of the graphene modified basalt fiber, which specifically comprises the following steps:

[0071] 101: placing the basalt fiber in an oxygen-enriched air atmosphere to perform first heat treatment;

[0072] In step 101, the volume fraction of oxygen in the oxygen-enriched air is 25%-30%, preferably 30%. This step is a surface activation treatment of the fiber to enhance adhesion.

[0073] The first heat treatment comprises: first treating at a first temperature for a first time in a muffle furnace, then treating at a second temperature for a second time after being heated to the second temperature, then treating at a third temperature for a third time after being heated to the third temperature, and then cleaning with n-propanol and pure water in sequence and drying for standby use after natural cooling. The three-stage treatment is mainly used to achieve the purpose of activation after surface treatment, and at the same time, serious defects are avoided.

[0074] In the first heat treatment, the first temperature is 480-520 DEG C, the first time is 50-60 min, the second temperature is 580-600 DEG C, the second time is 20-30 min, the third temperature is 680-700 DEG C, and the third time is 20-30 min.

[0075] Preferably, the first temperature is 500℃, the first time is 1h, the second temperature is 600℃, the second time is 0.5h, the third temperature is 700℃, and the third time is 0.5h.

[0076] 102: After the first heat treatment, the basalt fiber is coated with an aqueous graphene oxide solution, and then subjected to a second heat treatment under inert gas protection.

[0077] In step 102, high-purity (≥99%wt%) graphene with a particle size of 500-1000nm is ultrasonically dispersed in pure water for a period of time, and an aqueous graphene oxide solution of 0.5-0.7mg / mL is calculated and prepared. The ultrasonic dispersion time is determined according to actual needs, for example, 1.5h. Preferably, an aqueous graphene oxide solution of 0.6mg / mL is used.

[0078] The coating of the aqueous graphene oxide solution specifically includes: using a spin coating process to coat the basalt fiber after the first heat treatment with graphene oxide, and drying for a period of time. This step is repeated multiple times according to the coating situation, for example, 15-20 times. The duration of each coating and the drying temperature can be determined according to actual needs, for example, the duration of each coating is 3 minutes, and the drying temperature is 50℃.

[0079] The second heat treatment includes: treating at a fourth temperature for a fourth time, then increasing the temperature to a fifth temperature for a fifth time, and finally naturally cooling to obtain a graphene-basalt fiber composite fiber; using a two-stage process, the low-temperature stage is slightly longer to remove most of the oxygen-containing groups, and the high-temperature stage is shorter to remove the oxygen-containing groups while causing fewer defects.

[0080] The second heat treatment is to be protected by inert gas. The inert gas is one or more of helium and neon.

[0081] The fourth temperature is 650-700℃, the fourth time is 10-20min, the fifth temperature is 700-750℃, and the fifth time is 5-15min.

[0082] Preferably, the fourth temperature is 700℃, the fourth time is 15min, the fifth temperature is 750℃, and the fifth time is 15min.

[0083] 103: The basalt fiber after the second heat treatment is placed in polydimethylsiloxane containing 1%-3% organic peroxide curing agent for vacuum impregnation and curing to obtain a graphene-modified basalt fiber.

[0084] The impregnation time, the curing temperature and the curing time can be determined according to actual preparation needs, for example, the impregnation time is 10-15 min, the curing temperature is 95-100 DEG C, and the curing time is 50-60 min.

[0085] The organic peroxide curing agent is dibutyl phthalate DBP or benzoyl peroxide BPO.

[0086] The curing agent, that is, the crosslinking initiator, is used to initiate the crosslinking reaction of the active groups in the polydimethylsiloxane to form a flexible film adhered to the basalt fiber surface, which can be understood as a binder to firmly fix the graphene on the basalt fiber surface.

[0087] The rare earth oxide modified carbon nanotube is prepared by the method, and the preparation method of the rare earth oxide modified carbon nanotube comprises the following steps:

[0088] 201: The rare earth oxide and the carbon nanotube are added into concentrated nitric acid, and then separated after refluxing.

[0089] The mass ratio of the rare earth oxide to the carbon nanotube is 1:1.

[0090] The rare earth oxide is a mixed particle, and if the rare earth oxide is Er2O3 and Eu2O3, the mass ratio of Er2O3 to Eu2O3 is 3-2:1; if the rare earth oxide is Sm2O3, Er2O3 and Eu2O3, the mass ratio of Sm2O3, Er2O3 and Eu2O3 is 1:(1-2):1.

[0091] The concentration of the concentrated nitric acid used in the above method is 70%-75%, the refluxing temperature is 90-95 DEG C, and the refluxing time is 24-36 h.

[0092] In order to better perform the reaction, the ultrasonic oscillation dispersion is further performed before refluxing, and the ultrasonic time is determined according to actual needs, for example, the ultrasonic oscillation time is 2 h. After separation, the product is washed to neutral with deionized water and dried, and the drying temperature and time can be determined according to actual needs, for example, the product is dried in an 80 DEG C oven for 48 h.

[0093] 202: The separated product is subjected to a third heat treatment under inert gas protection to obtain the rare earth oxide modified carbon nanotube.

[0094] The inert gas is one or more of helium and neon.

[0095] The third heat treatment comprises: first treating at 400-450 DEG C for 60-80 min, then treating at 450-500 DEG C for 50-60 min, and finally treating at 500-520 DEG C for 50-60 min and naturally cooling to room temperature.

[0096] Preferably, the third heat treatment comprises: first treating at 400℃ for 1h, then treating at 450℃ for 1h, and finally treating at 500℃ for 1h and naturally cooling to room temperature.

[0097] The embodiment of the present application also provides an environmental member for radar, wherein the material of the environmental member is the wave-absorbing composite material as described in the above embodiment; or the material of the environmental member is the wave-absorbing composite material prepared by the preparation method of the wave-absorbing composite material as described in the above embodiment.

[0098] Referring to Figure 1 The surface of the environmental member is formed with a convex texture to further improve the wave-absorbing performance. The bionic etching texture treatment is performed on the surface of the sample to simulate the concave-convex texture of the eyes of insects and further improve the wave-absorbing performance.

[0099] The convex texture has various shapes, for example, the convex texture is in a honeycomb shape or a wedge shape.

[0100] The embodiment of the present application also provides a preparation method of an environmental member for radar, which comprises the following steps:

[0101] The wave-absorbing composite material is injection molded by an injection molding machine or is printed by a 3D printer.

[0102] For the injection molding scheme, the wave-absorbing composite material is injection molded into a desired part shape by the injection molding machine, and then corresponding texture etching is performed on the surface of the part. The corresponding convex texture can be obtained by mold imprinting or laser program carving. For example, the honeycomb-shaped holes as shown in Figure 2 are machined on the arc surface of the cylindrical steel material (for example, the diameter of each hole near one end of the arc surface is 100 nm, and the depth of each hole is about 250 nm) to form a mold, the mold is heated to 200℃ (slightly higher than the melting point of PA11), and then the surface of the part is imprinted with a texture under a pressure of 0.1 MPa to form the convex texture as shown in Figure 1 The surface convex structure of the part can significantly reduce reflected waves and scattered waves, improve the signal-to-noise ratio, and reduce the interference of clutter on the sensor. Through experiments, the 2mm-thick radar support is tested by the QAR method for 77Ghz millimeter wave electromagnetic loss, the transmission loss is greater than or equal to 14dB, and the reflection loss is greater than or equal to 6dB, which fully meets the wave-absorbing parameter index of the millimeter wave radar support.

[0103] The above environmental member can be a radar support and the like.

[0104] For the 3D printing scheme, specifically including: the dried wave-absorbing composite material is added into a high-speed blender for fully stirring and uniformity. Then, melt blending extrusion is carried out in a double-screw extruder, by selecting different aperture outlet dies, the required different aperture filaments can be extruded, collected into a roll through a disc concentrator, and the 3D printing special filament (a small amount of PE wax and stearic acid need to be added as lubricants in the extrusion filament making process) is obtained. Then, the printing parameters are input on the 3D printer, and the environmental part with wave-absorbing performance is printed, such as a radar support.

[0105] For example, as an example, the 3D printing parameters are as shown in Table 1:

[0106] Table 1

[0107]

[0108] It can be seen that the environmental part is prepared by using the wave-absorbing composite material obtained by taking nylon PA11 bio-based resin as a base material and using graphene modified basalt fiber and rare earth oxide modified carbon nanotube for modification, which is more environmentally friendly and low-carbon, and can be prepared by conventional injection molding and 3D printing, which is conducive to the batch production of products.

[0109] The application also provides a radar, which comprises the environmental part for radar as described in the above embodiments, and a radar wave-transparent sheet window, the environmental part further comprising a window, and the radar wave-transparent sheet window is arranged in the window of the environmental part.

[0110] The radar provided by the application has good wave-absorbing performance for 77GHZ millimeter waves and other frequency bands, effectively improves the signal-to-noise ratio, and avoids the occurrence of false positives and false negatives.

[0111] The radar wave-transparent sheet window comprises a visible light wave band transparent module, a 77GHZ wave band transparent module and a laser wave band transparent module, and the visible light wave band transparent module, the 77GHZ wave band transparent module and the laser wave band transparent module are connected side by side in a designed order; the radar wave-transparent sheet window is movably arranged on the environmental part, so that the visible light wave band transparent module, the 77GHZ wave band transparent module and the laser wave band transparent module are selectively switched into the window.

[0112] In this embodiment, the radar wave-transparent sheet window uses three modules of window interconnection, respectively for visible light waveband, 77GHZ millimeter wave band and laser waveband, and can realize the corresponding window switching to the corresponding position when the waveband function is switched. The function collocation is more flexible, the multi-mode adaptation scene switching makes the product more competitive, for example, the infrared night vision mode, the laser detection mode and the millimeter wave detection mode all have good product performance. The window modular production collocation can select the type and quantity of collocation according to the configuration needs, which is more easy for actual production.

[0113] The material of the visible light waveband wave-transparent module includes at least one of optical-grade glass lens and light-guiding-grade polycarbonate PC material. Good light transmission effect can be achieved, and this module can adapt to the output of optical sensors to output traditional optical signal patterns.

[0114] The material of the 77GHZ waveband wave-transparent module includes at least one of polycarbonate PC, glass fiber modified material of polycarbonate PC, polybutylene terephthalate PBT and glass fiber modified material of polybutylene terephthalate PBT; good wave transmission performance can be achieved.

[0115] The material of the laser waveband wave-transparent module includes at least one of polycarbonate PC, polybutylene terephthalate PBT and polycarbonate PC containing 0.5% to 1% black azo pigment color master modifier by mass fraction. The transmission performance of infrared waveband laser can be well achieved and the working temperature of about 100℃ can be met.

[0116] The black azo pigment color master modifier can use azo red: azo yellow: azo blue = 1:1.2 to 1.5:1 (mass ratio).

[0117] The polycarbonate PC can achieve a transmittance of more than 90% (2mm thick sample) for common infrared laser wavebands of 905nm and 1550nm without modification.

[0118] In order to reduce the influence of visible light on infrared radar, about 1% of black azo pigment color master modifier is added to the polycarbonate PC, which can achieve a transmittance of less than 5% (2mm thick sample) for the 400-700nm visible light waveband, significantly reducing the influence of visible light on near-infrared waveband signals and improving the signal-to-noise ratio.

[0119] The design sequence is: visible light waveband wave-transparent module, 77GHZ waveband wave-transparent module and laser waveband wave-transparent module; or, visible light waveband wave-transparent module, 77GHZ waveband wave-transparent module and laser waveband wave-transparent module; or, 77GHZ waveband wave-transparent module, visible light waveband wave-transparent module and laser waveband wave-transparent module; or, 77GHZ waveband wave-transparent module, laser waveband wave-transparent module and visible light waveband wave-transparent module.

[0120] Different frequency band wave-transparent materials are made into standard size wave-transparent modules, and the modules can be connected by means of gluing, welding and the like.

[0121] In order to switch the visible light band wave-transparent module, the 77GHZ band wave-transparent module and the laser band wave-transparent module into the window alternatively, there are many specific implementation manners for movably arranging the radar wave-transparent sheet window on the environmental member, and all of them can be realized by using existing conventional schemes.

[0122] For example, a tiny transmission mechanism is used for translation, so that the wave-transparent module of the corresponding mode can always be in the middle window position.

[0123] For another example, a track form can also be used, the upper side is a fixed track, only the inner and outer sides are fixed. The lower side is a movable track, not only the inner and outer sides are fixed, but also there is a rectangular clamping groove corresponding to the size of the bottom of the wave-transparent module. The whole clamping groove can be driven to translate left and right by a transmission system, and the corresponding wave-transparent module can also translate.

[0124] Embodiment 1

[0125] A preparation method of a radar support, comprising the following steps:

[0126] (1) Preparation of graphene modified basalt fiber

[0127] 101: The basalt fiber is placed in a muffle furnace, heated to 500℃ under an oxygen-enriched air atmosphere (30% oxygen), treated for 1h, then raised to 600℃ for 0.5h, and finally raised to 700℃ for 0.5h, and then naturally cooled, and cleaned with n-propanol and pure water before and after drying for standby use.

[0128] 102: High-purity (>99%wt%) graphene with a particle size of 500nm-1000nm is used. The graphene oxide aqueous solution is prepared by ultrasonic dispersion in pure water for 1.5h, and the concentration is 0.6mg / mL. The graphene oxide is coated on the heat-treated basalt fiber by spin coating process, and dried at 50℃ for 3 minutes. This step is repeated 20 times. The graphene-coated basalt fiber is heated to 700℃ in a muffle furnace under neon atmosphere, treated for 15min, then raised to 750℃ for 15min, and finally naturally cooled to obtain graphene and basalt fiber composite fiber.

[0129] 103: The graphene and basalt fiber composite fiber is placed in polydimethylsiloxane (containing 2% organic peroxide curing agent DBP) for vacuum impregnation for 10min, and then cured at 100℃ in a drying oven for 50min, thereby obtaining graphene modified basalt fiber material.

[0130] (2) Preparation of rare earth oxide modified carbon nanotube

[0131] 201: Take 0.75 g of Er203, 0.25 g of Eu203 and 1 g of multi-walled carbon nanotubes into a 500 ml round bottom flask containing 200 ml of concentrated nitric acid (70%~75%). Use ultrasonic oscillation for 2 h to ensure that the nanoparticles are fully dispersed. Then the mixture is refluxed at 90°C for 24 h. The product is separated by centrifuge, and the obtained product is washed to neutral with deionized water and dried in an oven at 80°C for 48 h.

[0132] 202: The separated product is heated in a muffle furnace under a neon atmosphere, and is sequentially treated at 400°C for 1 h, at 450°C for 1 h, and finally at 500°C for 1 h, and then naturally cooled to room temperature to obtain rare earth oxide modified carbon nanotubes.

[0133] (3) Modified PA11 granulation

[0134] The dried (80°C, 8 h) mass fraction of 65% nylon PA11, 5% rare earth oxide modified carbon nanotubes and 30% graphene modified basalt short fibers are first fully stirred and mixed uniformly, and then melt blended and granulated at 260°C.

[0135] (4) Sample forming

[0136] After granulation, an injection molding machine is used to injection molding into samples.

[0137] (5) Surface texture etching

[0138] The corresponding convex texture is engraved by mold stamping or laser program, and the final radar support is obtained. The mold is shown in Figure 2 , and the honeycomb-shaped holes shown in Figure 2 are machined on the arc surface of the cylindrical steel, and the diameter of each hole near the arc surface is 100 nm, and the depth of each hole is about 250 nm.

[0139] Example 2:

[0140] A method for preparing a radar support, comprising the following steps:

[0141] (1) Preparation of graphene modified basalt fiber

[0142] The same as example 1.

[0143] (2) Preparation of rare earth oxide modified carbon nanotubes

[0144] The same as example 1.

[0145] (3) Modified PA11 granulation

[0146] Except for the mass ratio of 70% nylon PA11, 5% rare earth oxide modified carbon nanotubes, 25% graphene modified basalt short fibers, the rest is the same as example 1.

[0147] (4) sample forming

[0148] The dried (80℃, 8h) 70% nylon PA11, 5% rare earth oxide modified carbon nanotubes, 25% graphene modified basalt short fibers were added to a high-speed blender and stirred evenly. Then melt blending extrusion was carried out in a twin-screw extruder, by selecting different pore sizes of the outlet die, the required different pore size of the filament (the most common is 1.75±0.1mm) can be extruded, and collected into a roll by a disc concentrator, to obtain a 3D printing special filament (a small amount of PE wax and stearic acid need to be added as lubricant during the extrusion process). Then input the printing parameters on the 3D printer, and print out the radar support with wave absorbing performance.

[0149] (5) surface texture etching

[0150] The same as example 1.

[0151] Example 3:

[0152] A method for preparing a radar support, comprising the following steps:

[0153] (1) preparation of graphene modified basalt fiber

[0154] The same as example 1.

[0155] (2) preparation of rare earth oxide modified carbon nanotubes

[0156] Except for the mass ratio of Sm2O3:Er2O3:Eu2O3=1:2:1, the rest is the same as example 1.

[0157] (3) modification of PA11 granulation

[0158] The same as example 1.

[0159] (4) sample forming

[0160] The same as example 1.

[0161] (5) surface texture etching

[0162] The same as example 1.

[0163] Example 4:

[0164] A method for preparing a radar support, comprising the following steps:

[0165] (1) preparation of graphene modified basalt fiber

[0166] The same as Example 1.

[0167] (2) Preparation of rare earth oxide modified carbon nanotubes

[0168] The same as Example 1 except that the mass ratio is Sm2O3:Er2O3:Eu2O3 = 1:2:1.

[0169] (3) Modification of PA11 granulation

[0170] The same as Example 1 except that the mass fraction is: 70% nylon PA11, 5% rare earth oxide modified carbon nanotubes, 25% graphene modified basalt short fibers.

[0171] (4) Sample forming

[0172] The dried (80℃, 8h) 70% nylon PA11, 5% rare earth oxide modified carbon nanotubes, 25% graphene modified basalt short fibers are added to a high-speed blender and stirred evenly. Then melt-blending extrusion is carried out in a twin-screw extruder, and by selecting different pore sizes of the outlet die, the required different pore size of the filament (the most common is 1.75±0.1mm) can be extruded, and collected into a roll by a disc concentrator, to obtain a filament material special for 3D printing (a small amount of PE wax and stearic acid need to be added as lubricants during the extrusion process). Then input the printing parameters on the 3D printer, and print out the radar support with wave absorption performance.

[0173] (5) Surface texture etching

[0174] The same as Example 1.

[0175] Example 5:

[0176] A method for preparing a radar support, comprising the following steps:

[0177] (1) Preparation of graphene modified basalt fiber

[0178] The same as Example 1.

[0179] (2) Preparation of rare earth oxide modified carbon nanotubes

[0180] The same as Example 1 except that the mass ratio is Sm2O3:Er2O3:Eu2O3 = 1:1:1.

[0181] (3) Modification of PA11 granulation

[0182] The same as Example 1.

[0183] (4) Sample forming

[0184] The same as Example 1.

[0185] (5) surface texture etching

[0186] The same as example 1.

[0187] Example 6:

[0188] A method for preparing a radar support includes the following steps:

[0189] (1) Preparation of graphene modified basalt fiber

[0190] The same as example 1.

[0191] (2) Preparation of rare earth oxide modified carbon nanotubes

[0192] The same as example 1 except that the mass ratio of Sm2O3:Er2O3:Eu2O3 is 1:1:1.

[0193] (3) Modification of PA11 granulation

[0194] The same as example 1 except that the mass fraction is: 70% nylon PA11, 5% rare earth oxide modified carbon nanotubes, 25% graphene modified basalt short fiber.

[0195] (4) Sample forming

[0196] The dried (80℃, 8h) 70% nylon PA11, 5% rare earth oxide modified carbon nanotubes, 25% graphene modified basalt short fiber is added to a high-speed blender and stirred evenly. Then melt blending extrusion is carried out in a twin-screw extruder, and by selecting different pore sizes of the outlet die, the required different pore size of the filament (the most common is 1.75±0.1mm) can be extruded, and collected into a roll by a disc concentrator, to obtain a 3D printing special filament (a small amount of PE wax and stearic acid need to be added as lubricant during the extrusion process). Then input the printing parameters on the 3D printer, and print out the radar support with wave absorption performance.

[0197] (5) surface texture etching

[0198] The same as example 1.

[0199] The above examples 1-6 are tested according to GB / T 30142-2013 Planar electromagnetic shielding material shielding effectiveness measurement method, and the test results are shown in the following table 2.

[0200] Table 2

[0201]

[0202] Reflection loss R LThe 1550nm infrared wave mainly considers the ability of the material environmental part to suppress the corresponding noise when the signal source and the detection object are switched to infrared waves.

[0203] The loss effects of examples 1, 3 and 5 are not much different at 77GHz, within 6%, due to the total content of the same rare earth added being 5% (other components are consistent), and the different proportions. Examples 2, 4 and 6 have a certain degree of reduction in loss effect compared to ordinary molding formulas with the same content of rare earth, due to the reduction of the content of graphene modified fiber and the increase of the proportion of resin, which is limited by the 3D printing processing conditions. The reduction of functional ingredients and the destruction of microstructure by more stringent blending conditions will cause different degrees of reduction in loss performance.

[0204] In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise expressly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0205] It should be noted that in the present application, relational terms such as "first" and "second" and the like are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the sentence "including a…" does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0206] The foregoing detailed description of the application has been presented for purposes of illustration and description. Various modifications and changes can be made to these embodiments without departing from the spirit and scope of the application. It is intended that the scope of the application should not be limited by the particular representative embodiments described above.

Claims

1. A method for preparing a wave-absorbing composite material, characterized in that, The wave-absorbing composite material comprises, in terms of mass fraction: 25%-35% graphene modified basalt fiber, 5%-10% rare earth oxide modified carbon nanotube, and 55%-70% nylon PA11; The preparation method comprises the following steps: The 25%-35% graphene modified basalt fiber, 5%-10% rare earth oxide modified carbon nanotube, and 55%-70% nylon PA11 are first stirred and uniformly mixed, and then subjected to melt blending and granulation under the condition of 240-260 ℃ to obtain the wave-absorbing composite material. The preparation method of the graphene modified basalt fiber comprises the following steps: The basalt fiber is placed in an oxygen-enriched air atmosphere and subjected to first heat treatment; the first heat treatment comprises the following steps: first treated at 480-520 ℃ for 50-60 min, then heated to 580-600 ℃ for 20-30 min, and then heated to 680-700 ℃ for 20-30 min, and then naturally cooled, cleaned and dried; After the first heat treatment, the basalt fiber is coated with an aqueous graphene oxide solution, and then subjected to second heat treatment under inert gas protection; the second heat treatment comprises the following steps: treated at 650-700 ℃ for 10-20 min, and then heated by 50 ℃ to 700-750 ℃ for 5-15 min; The basalt fiber after the second heat treatment is vacuum impregnated in polydimethylsiloxane containing 1%-3% organic peroxide curing agent and then cured to obtain the graphene modified basalt fiber.

2. The preparation method of the wave-absorbing composite material according to claim 1, wherein: The particle size of the graphene is 500-1000 nm; And / or, the length of the graphene modified basalt fiber is 1-25 mm; And / or, the rare earth oxide is in the form of particles with a particle size of 3-20 nm; And / or, the rare earth includes one or more of samarium (Sm), erbium (Er) and europium (Eu).

3. The preparation method of the wave-absorbing composite material according to claim 1, wherein: In the oxygen-enriched air, the volume fraction of oxygen is 25%-30%; And / or, the concentration of the aqueous graphene oxide solution is 0.5-0.7 mg / ml; And / or, the impregnation time is 10-15 min; And / or, the curing temperature is 95-100 ℃, and the curing time is 50-60 min; And / or, the organic peroxide curing agent is dibutyl phthalate (DBP) or benzoyl peroxide (BPO).

4. The method for preparing the microwave absorbing composite material as described in claim 1, characterized in that, The preparation method of the rare earth oxide modified carbon nanotube comprises the following steps: The rare earth oxide and the carbon nanotube are added to concentrated nitric acid, refluxed and then separated; The separated product is subjected to third heat treatment under inert gas protection to obtain the rare earth oxide modified carbon nanotube.

5. The preparation method of the wave-absorbing composite material according to claim 4, wherein: The mass ratio of the rare earth oxide to the carbon nanotube is 1:1; And / or, the rare earth oxide includes Er2O3 and Eu2O3, and the mass ratio of Er2O3 to Eu2O3 is 3-2:

1. And / or, the rare earth oxide includes samarium Sm2O3, Er2O3 and Eu2O3, and the mass ratio of Sm2O3, Er2O3 and Eu2O3 is 1: (1-2): 1; And / or, the concentration of concentrated nitric acid is 70%-75%; And / or, before refluxing, it is also dispersed by ultrasonic oscillation; And / or, the refluxing temperature is 90-95℃, and the time is 24-36h; And / or, after separation, before the third heat treatment, it is also washed with deionized water to neutral and dried; And / or, the inert gas uses one or more of helium and neon; And / or, the third heat treatment includes: first at 400-450℃ for 60-80min, then at 450-500℃ for 50-60min, and finally at 500-520℃ for 50-60min and naturally cooled to room temperature.

6. An environmental part for radar, characterized in that: The material of the environmental part is the wave-absorbing composite material prepared by the preparation method of the wave-absorbing composite material according to any one of claims 1-5.

7. The environmental member for radar use according to claim 6, characterized in that: The surface of the environmental part is formed with raised textures.

8. The environmental member for radar use according to claim 7, characterized in that: The raised textures are in honeycomb shape or wedge shape.

9. A method of producing an environmental member for a radar as claimed in any one of claims 6 to 8, characterized in that, It comprises: The wave-absorbing composite material is injection molded by an injection molding machine; Or, the wave-absorbing composite material is printed by a 3D printer.

10. A radar, characterized by: It comprises the environmental part for radar according to any one of claims 6-8, and a radar wave-transparent sheet window, and the environmental part also has a window, and the radar wave-transparent sheet window is in the window of the environmental part.

11. The radar according to claim 10, characterized in that: The radar wave-transparent sheet window comprises a visible light wave band wave-transparent module, a 77GHZ wave band wave-transparent module and a laser wave band wave-transparent module, and the visible light wave band wave-transparent module, the 77GHZ wave band wave-transparent module and the laser wave band wave-transparent module are connected side by side in a designed order; The radar wave-transparent sheet window is movably arranged on the environmental part, so that the visible light wave band wave-transparent module, the 77GHZ wave band wave-transparent module and the laser wave band wave-transparent module are selectively switched into the window.

12. The radar according to claim 11, characterized in that: The designed order is: visible light wave band wave-transparent module, 77GHZ wave band wave-transparent module and laser wave band wave-transparent module; or visible light wave band wave-transparent module, 77GHZ wave band wave-transparent module and laser wave band wave-transparent module; or 77GHZ wave band wave-transparent module, visible light wave band wave-transparent module and laser wave band wave-transparent module; or 77GHZ wave band wave-transparent module, laser wave band wave-transparent module and visible light wave band wave-transparent module.

13. The radar according to claim 11, characterized in that: The material of the visible light wave band wave-transparent module comprises at least one of optical-grade glass lens and light-guiding-grade polycarbonate PC material.

14. The radar according to claim 11, characterized in that: The material of the 77GHZ wave band wave-transparent module comprises at least one of polycarbonate PC, glass fiber modified polycarbonate PC, polybutylene terephthalate PBT and glass fiber modified polybutylene terephthalate PBT.

15. The radar according to claim 11, characterized in that: The material of the laser wave band transparent wave module includes at least one of polycarbonate PC, polybutylene terephthalate PBT and polycarbonate PC containing 0.5% to 1% of black azo pigment color master modifier in mass fraction.

16. The radar of claim 15, wherein: The black azo pigment color master modifier includes azo red, azo yellow and azo blue, and the mass ratio of azo red: azo yellow: azo blue is 1:1.2-1.5:1.

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