A metallized rigid thermal insulation material for patch antennas and its preparation method

Abstract

The present invention provides a metallized rigid thermal insulation material for patch antennas and a preparation method thereof, belonging to the field of thermal insulation materials. The preparation method of the metallized rigid thermal insulation material for patch antennas consists of the following steps: slurry preparation, filtration molding, densification treatment, metallization treatment, and laser processing. The metallized rigid thermal insulation material for patch antennas and the preparation method thereof of the present invention can effectively avoid the loose and porous structural limitations of rigid thermal insulation materials, and can prepare fine metal units on the surface of rigid thermal insulation and wave-transmitting materials to exert antenna functions, thereby effectively overcoming the serious electrical loss and insufficient temperature resistance of existing patch array antennas.

Description

Technical Field

[0001] The invention relates to the field of heat-insulating materials, and in particular to a metallized rigid heat-insulating material for a patch antenna and a preparation method thereof. Background Art

[0002] The patch antenna has the characteristics of compact structure, small size, light weight and strong designability. It is used as an aircraft radar communication antenna. Its structural form is generally composed of a multi-element array plane and a feed source. The shape of the directional pattern and the maximum direction of the directional pattern are changed by controlling the feeding phase of the radiating unit in the array antenna to achieve the purpose of beam scanning. In the prior art, researchers have carried out a lot of research on patch array antennas and made certain progress, but the design and application of its patch array antenna mainly rely on PCB board technology, usually in the form of PCB / metal array element multi-layer alternation to achieve the various radiation functions of the antenna. However, in the actual application of aircraft, on the one hand, the temperature resistance of the PCB board is insufficient and it cannot be used under the high Mach conditions of the aircraft; on the other hand, in order to effectively reduce dielectric loss and improve radiation efficiency, the ideal dielectric substrate is "air". Therefore, the researchers support the metal patch with a dielectric column to achieve "air elevation", but the dielectric column will undoubtedly cause additional electrical loss and inconvenience in application.

[0003] Rigid thermal insulation and wave-transmitting materials have the advantages of light weight, ultra-low dielectric and high temperature resistance, and have been widely used in various types of aircraft antennas and their thermal protection parts. Preparing metal array elements on the surface of rigid thermal insulation and wave-transmitting materials can effectively solve the serious power loss and insufficient temperature resistance problems faced by the above-mentioned patch array antennas. However, due to the loose porous structure of rigid thermal insulation materials (air volume accounts for more than 90%), preparing fine metal units on their surface to perform antenna functions has always been a technical difficulty in this field. Therefore, the breakthrough of this technology is of great significance to the development and application of high-temperature resistant patch antennas.

[0004] Therefore, a method for preparing a metallized rigid thermal insulation material for a patch antenna is provided, which effectively avoids the loose and porous structural limitations of the rigid thermal insulation material, can prepare fine metal units on the surface of the rigid thermal insulation and wave-transmitting material to exert the antenna function, and thus effectively overcomes the serious electrical loss and insufficient temperature resistance of existing patch array antennas, which has important technical significance and research value. Summary of the invention

[0005] In order to solve the technical problems existing in the prior art, the present invention provides a metallized rigid thermal insulation material for patch antennas and a preparation method thereof, which can effectively avoid the loose and porous structural limitations of the rigid thermal insulation material, and can prepare fine metal units on the surface of the rigid thermal insulation and wave-transmitting material to exert the antenna function, thereby effectively overcoming the serious electrical loss and insufficient temperature resistance of the existing patch array antenna.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a metallized rigid heat-insulating material for a patch antenna, comprising the following steps: slurry preparation, filtration molding, densification treatment, metallization treatment, and laser processing;

[0008] The method for preparing the slurry is as follows: short-cut fibers, aluminum silica sol, sintering aid, modified ceramic hollow ball powder and deionized water are uniformly mixed to obtain a first matrix slurry; short-cut fibers, aluminum silica sol, sintering aid and deionized water are uniformly mixed to obtain a second matrix slurry;

[0009] The modified ceramic hollow sphere powder is hollow silicon oxide sphere powder and / or hollow aluminum oxide sphere powder modified by a silane coupling agent;

[0010] The filtration molding method comprises pouring a first matrix slurry in a mold, vacuum filtration to form a first layer of filter cake, pouring a second matrix slurry when the slurry liquid level drops to the same level as the first layer of filter cake, and vacuum filtration to form a second layer of filter cake; drying and sintering to obtain a rigid thermal insulation material blank with a high-low porosity gradient distribution;

[0011] The densification treatment method is to process the rigid thermal insulation material blank with high and low porosity gradient distribution into a predetermined thickness, apply the densification slurry to the surface of the low-porosity thermal insulation layer of the rigid thermal insulation material blank, spray a reinforcing agent after drying, and sinter to obtain a rigid thermal insulation material with a densified surface layer;

[0012] The densified slurry is uniformly prepared by ball milling modified ceramic powder, aluminum silica sol and boric acid;

[0013] The metallization treatment method is to spray a metal slurry spray coating onto the densified surface of the rigid thermal insulation material, and obtain a rigid thermal insulation material with a metal coating after drying and sintering;

[0014] The laser processing method comprises: performing laser etching on the metal coating of the rigid heat-insulating material to obtain the metallized rigid heat-insulating material that can be used for the patch antenna.

[0015] Preferably, in the first matrix slurry, the mass fraction of chopped fibers is 5-10wt%, the mass fraction of aluminum silica sol is 2-7wt%, the mass fraction of sintering aid is 0.5-1.0wt%, the mass fraction of modified ceramic hollow sphere powder is 3-5wt%, and the balance is deionized water;

[0016] In the second matrix slurry, the mass fraction of chopped fibers is 8-10wt%; the mass fraction of aluminum silica sol is 2-7wt%; the mass fraction of sintering aid is 0.5-1.0wt%, and the balance is deionized water.

[0017] Preferably, in the preparation of the slurry, the chopped fibers are a combination of quartz fibers, alumina fibers, and mullite fibers with a length of 20-250 μm; the solid content of the aluminum silica sol is 20-25 wt %; and the sintering aid is boron oxide and / or boron nitride;

[0018] The silane coupling agent used in the modified ceramic hollow ball powder is at least one of the following: silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570.

[0019] Preferably, in the suction filtration molding, the thickness of the first layer of filter cake is controlled to 3-5 mm, and the thickness of the second layer of filter cake is controlled to 5-15 mm;

[0020] The sintering temperature is 1200-1300°C and the sintering time is 2-4h.

[0021] Preferably, in the densification treatment, the rigid thermal insulation material blank with high and low porosity gradient distribution is processed into a thickness of 3-5 mm, and a low-porosity thermal insulation layer with a thickness of 0.5-0.8 mm is retained;

[0022] The coating layer thickness of the densified slurry is 0.02-0.1 mm.

[0023] Preferably, in the densified slurry, the modified ceramic powder accounts for 30-45% of the total mass of the densified slurry; the aluminum silica sol accounts for 50-65% of the total mass of the slurry; and the balance is boric acid;

[0024] The modified ceramic powder is composed of silicon oxide, magnesium fluoride, lithium oxide and aluminum oxide in a mass ratio of 3-5:1:1:2-3; the silicon oxide is obtained by modification with a silane coupling agent; the aluminum oxide is obtained by modification with a silane coupling agent;

[0025] The solid content of aluminum silica sol is 20-25wt%;

[0026] The mass concentration of boric acid is 3-5wt%;

[0027] The strengthening agent is a toluene or xylene solution of polysilazane or polysiloxane, and the mass fraction of polysilazane or polysiloxane in the strengthening agent is 30-40%.

[0028] Preferably, in the metallization treatment, the metal slurry spray coating is controlled to be 2 The spraying amount of the densified surface of the rigid insulation material is 1.0-1.5g;

[0029] The metal slurry spray coating is prepared by diluting highly conductive metal slurry with a diluent; the diluent is an ethanol or propanol solution of butyl carbitol or terpineol.

[0030] Preferably, the highly conductive metal slurry is one of the following: silver slurry, gold slurry, platinum slurry, silver-palladium alloy slurry;

[0031] The mass fraction of butyl carbitol or terpineol in the diluent is 8-15%;

[0032] The amount of the diluent is 25-35% of the total weight of the metal slurry spray coating.

[0033] Preferably, in the laser processing, a picosecond laser is used for laser etching; the laser power is controlled to be 2-5W, the linear speed is 300-500mm / s, and the number of etchings is 2-4 times.

[0034] A metallized rigid thermal insulation material for a patch antenna, which is manufactured by the aforementioned method, is provided with: a high-porosity thermal insulation layer, a low-porosity thermal insulation layer, a dense layer, and a metal patch layer in sequence.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The method for preparing the metallized rigid thermal insulation material for patch antennas of the present invention realizes the transition of the matrix from a high-porosity structure to a low-porosity structure by controlling the molding of the rigid thermal insulation material; realizes surface densification by coating a special slurry, thereby improving the adhesion of the metal coating to the thermal insulation material and its surface consistency and microscopic continuity; obtains different types of metal patch structures by a spraying process combined with laser etching; and obtains metallized rigid thermal insulation materials for patch antennas with different temperature resistance grades by selecting different metal slurries; can effectively avoid the loose and porous structural limitations of the rigid thermal insulation material, can prepare fine metal units on the surface of the rigid thermal insulation and wave-transmitting material to exert the antenna function, thereby effectively overcoming the serious power loss and insufficient temperature resistance of the existing patch array antenna.

[0037] (2) The metallized rigid thermal insulation material for patch antennas of the present invention has a porosity of more than 90% and a thermal conductivity of no more than 0.06 W•m -1 •k -1 The porosity of the low-porosity insulation layer is less than 15%, and the thermal conductivity is not higher than 0.1W•m -1 •k -1 ; The adhesion between the metal patch and the rigid insulation material substrate was evaluated as level 0 using the ISO 2409 method.

[0038] (3) The preparation method of the metallized rigid thermal insulation material for patch antennas of the present invention is to design a gradient structure of the rigid wave-transmitting thermal insulation material and perform surface densification treatment, thereby making a breakthrough in preparing a metal coating on a loose and porous rigid thermal insulation material; secondly, the present invention introduces low thermal conductivity ceramic hollow sphere powder, which not only significantly reduces the porosity of the rigid thermal insulation material, but also does not significantly increase the thermal conductivity of the thermal insulation material; thirdly, the present invention develops a surface densification process and a densification slurry for the rigid thermal insulation material, which will not significantly affect the overall dielectric properties of the rigid thermal insulation material within the thickness range of the densified layer; thirdly, the present invention effectively combines the low dielectric properties and the temperature resistance and heat insulation properties of the rigid thermal insulation material, can effectively avoid the loose and porous structural limitations of the rigid thermal insulation material, can prepare fine metal units on the surface of the rigid thermal insulation and wave-transmitting material, and realize the "air elevation" of the radiation array element of the patch antenna, which provides a technical option for the application of patch antennas that can withstand higher temperatures; finally, the preparation method of the present invention has strong process applicability, simple operation, low equipment requirements, and does not require complex process equipment, which is conducive to large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic structural diagram of the metallized rigid thermal insulation material for patch antennas of the present invention; in the figure, 1-high-porosity thermal insulation layer, 2-low-porosity thermal insulation layer, 3-dense layer, 4-metal patch layer.

[0040] Figure 2 It is a schematic diagram of the metallized rigid thermal insulation material for patch antenna of the present invention. DETAILED DESCRIPTION

[0041] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described. It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those of ordinary skill in the art to which the present invention belongs.

[0042] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, "first", "second", etc. are used to distinguish similar objects, and are not used to describe a specific order or sequence. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0043] The embodiment of the present invention provides a method for preparing a metallized rigid thermal insulation material for a patch antenna, which is achieved by the following method:

[0044] First, a rigid thermal insulation material with a gradient pore structure is prepared and processed to a predetermined size; secondly, a densified slurry is prepared and coated on the surface of the rigid thermal insulation material, and the rigid thermal insulation material with a surface densification treatment is obtained through drying and sintering; thirdly, a metal slurry is coated on the densified surface of the rigid thermal insulation material by spraying, and the rigid thermal insulation material with a surface metallized is obtained through drying and sintering; finally, a metal radiation unit is processed on the surface metallized rigid thermal insulation material by laser etching, and finally a metallized rigid thermal insulation material that can be used for a patch antenna is obtained.

[0045] As a further elaboration of the above scheme, the preparation method of the metallized rigid thermal insulation material for the patch antenna of the present invention specifically comprises the following steps:

[0046] (1) Slurry preparation. Prepare two different components of thermal insulation material matrix slurries, the first matrix slurry is a mixture of chopped fibers, aluminum silica sol, sintering aid, modified ceramic hollow ball powder, and deionized water; the second matrix slurry is a mixture of chopped fibers, aluminum silica sol, sintering aid, and deionized water; mix the raw materials of the first matrix slurry and the second matrix slurry, adjust the pH of the matrix slurry, and evenly disperse it with a disperser to obtain the first matrix slurry and the second matrix slurry.

[0047] (2) Filtration molding. First, pour the first matrix slurry into the mold, and form the first filter cake (low-porosity insulation layer 2) through vacuum filtration. When the slurry liquid level drops to the same level as the first filter cake, slowly pour the second matrix slurry, and continue to form the second filter cake (high-porosity insulation layer 1) through vacuum filtration until the filtration is completed. Finally, after drying and sintering, a rigid insulation material blank with a high-low porosity gradient distribution is obtained.

[0048] (3) Densification treatment. The rigid thermal insulation material blank with high and low porosity gradient distribution obtained in step (2) is processed into a flat plate of predetermined size, and a low porosity thermal insulation layer of a certain thickness is retained. The densified slurry is evenly coated on the surface of the low porosity thermal insulation layer of the rigid thermal insulation material using a nylon brush. After drying and polishing, the thickness of the coating layer is controlled, and then a layer of strengthening agent is sprayed. Finally, it is sintered in a muffle furnace to densify the surface of the rigid thermal insulation material to form a dense layer 3, thereby obtaining a surface densified rigid thermal insulation material.

[0049] (4) Metallization treatment: Use the spraying method to spray the metal slurry spray coating on the densified surface of the rigid thermal insulation material, control the spraying weight gain, and after drying and sintering, the metal coating and the rigid thermal insulation material are well combined.

[0050] (5) Laser processing. The metal layer is finely processed into patch units by laser etching to form a metal patch layer 4, thereby obtaining a metalized rigid thermal insulation material (such as Figure 2 as shown).

[0051] Furthermore, in step (1), the chopped fibers include but are not limited to one or a combination of materials such as quartz fibers, alumina fibers, and mullite fibers, and the length of the chopped fibers is 20-250 μm; the solid content of the aluminum silica sol is 20-25 wt %; the sintering aid is boron oxide and / or boron nitride; and the modified ceramic hollow sphere powder is hollow silica sphere powder and / or hollow alumina sphere powder, with a diameter of 2-5 μm, obtained after being modified by one or more of the silane coupling agents KH550, KH560, and KH570.

[0052] Furthermore, the specific preparation method of the modified ceramic hollow sphere powder is to add a silane coupling agent to an ethanol aqueous solution (volume concentration of 10%) to obtain a modified solution; add silicon oxide and / or aluminum oxide hollow sphere powder to the modified solution for dispersion and modification, and then dry the solution to obtain the modified ceramic hollow sphere powder. The amount of the silane coupling agent used is 2-5% of the total mass of the hollow sphere powder.

[0053] Preferably, in step (1), in the first matrix slurry, the mass fraction of chopped fibers is 5-10wt%, the mass fraction of aluminum silica sol is 2-7wt%, the mass fraction of sintering aid is 0.5-1.0wt%, the mass fraction of modified ceramic hollow sphere powder is 3-5wt%, and the balance is deionized water; in the second matrix slurry, the mass fraction of chopped fibers is 8-10wt%, the mass fraction of aluminum silica sol is 2-7wt%, the mass fraction of sintering aid is 0.5-1.0wt%, and the balance is deionized water.

[0054] Furthermore, in step (2), the thickness of the first filter cake layer is controlled to 3-5 mm, and the thickness of the second filter cake layer is controlled to 5-15 mm.

[0055] In the step (2), the second filter cake is formed by liquid phase connection between the second matrix slurry and the first matrix slurry, rather than forming the second filter cake after the first filter cake is filtered.

[0056] In the step (2), the drying temperature is 50-60°C and the drying time is 8-12h; the sintering temperature is 1200-1300°C and the sintering time is 2-4h.

[0057] Furthermore, in step (3), the retained thickness of the low-porosity thermal insulation layer is controlled to be 0.5-1 mm.

[0058] In the step (3), the densified slurry is obtained by mixing modified ceramic powder, aluminum silica sol and boric acid through ball milling, and the ball milling time is 0.5-1h.

[0059] Preferably, the modified ceramic powder accounts for 30-45% of the total mass of the densified slurry, and is composed of silicon oxide, magnesium fluoride, lithium oxide, and aluminum oxide in a mass ratio of 3-5:1:1:2-3; wherein silicon oxide and aluminum oxide are modified by one or more of the silane coupling agents KH550, KH560, and KH570; the solid content of the aluminum silica sol is 20-25wt%, accounting for 50-65% of the total mass of the densified slurry; the balance is boric acid (boric acid concentration specification is 3-5wt%).

[0060] In the step (3), the coating layer thickness is controlled to be 0.02-0.1 mm, and after drying, it is polished smooth with 800-1000 mesh sandpaper.

[0061] In step (3), the reinforcing agent is a toluene or xylene solution of polysilazane or polysiloxane, and the mass fraction of polysilazane or polysiloxane in the reinforcing agent is 30-40%; the spraying amount of the reinforcing agent is 0.3-0.5 g / 100 cm 2 .

[0062] In the step (3), the sintering temperature is 850-1000°C, and the constant temperature sintering time is 2-4h.

[0063] Furthermore, in the step (4), the metal slurry spray coating is prepared by diluting the metal slurry with a diluent and using one of the following high-temperature resistant and oxidation-resistant highly conductive metal slurries: silver slurry, gold slurry, platinum slurry, and silver-palladium alloy slurry.

[0064] The highly conductive metal slurry is a conventional commercial product, which is composed of corresponding metal powder, epoxy resin, glass powder and solvent, wherein the content of the metal powder is 75-85wt%.

[0065] Preferably, the diluent is an ethanol (or propanol) solution of butyl carbitol (or terpineol); the mass fraction of butyl carbitol (or terpineol) in the diluent is 8-15%; and the amount of the diluent is 25-35% of the total weight of the metal slurry spray coating.

[0066] In the step (4), the spraying weight gain is controlled by controlling the feeding amount through the spraying times, and the thickness of the metal layer is intuitively controlled. Preferably, the spraying weight gain is controlled to be 100 cm 2 The amount of metal slurry spray coating applied to the surface of the rigid thermal insulation material is 1.0-1.5 g, so as to obtain a metal layer with a thickness of 8-15 μm.

[0067] In the step (4), the drying temperature is 85-100°C, and the drying time is 0.5-1h; the sintering temperature is 750-900°C, and the heat preservation sintering time is 15-30min.

[0068] Furthermore, in the step (5), the laser etching uses a 3D galvanometer to control the laser direction, and the etching is performed with a picosecond laser; the laser power is controlled to be 2-5 W, the linear speed is 300-500 mm / s, and the etching times are 2-4 times.

[0069] The preparation method of the metallized rigid thermal insulation material for the patch antenna of the present invention is to prepare the metal coating on the loose and porous rigid thermal insulation material by designing the gradient structure of the rigid wave-transparent thermal insulation material and performing surface densification treatment. Among them, the present invention not only significantly reduces the porosity of the rigid thermal insulation material, but also does not significantly increase the thermal conductivity of the thermal insulation material by introducing low thermal conductivity ceramic hollow sphere powder; at the same time, the present invention effectively avoids the significant impact on the overall dielectric properties of the rigid thermal insulation material within the thickness range of the dense layer through the densification treatment process and the densification slurry; and then further combines the low dielectric properties and temperature resistance and heat insulation properties of the rigid thermal insulation material, which can effectively avoid the loose and porous structural limitations of the rigid thermal insulation material, and can prepare fine metal units on the surface of the rigid thermal insulation and wave-transparent material, so as to realize the "air elevation" of the radiation array element of the patch antenna.

[0070] like Figure 1 As shown, the embodiment of the present invention also provides a metallized rigid thermal insulation material for a patch antenna prepared by the aforementioned method, which is sequentially provided with a high-porosity thermal insulation layer 1, a low-porosity thermal insulation layer 2, a dense layer 3, and a metal patch layer 4; the porosity of the high-porosity thermal insulation layer 1 is greater than 90%, and the thermal conductivity is not higher than 0.06W•m -1 •k -1 The porosity of the low-porosity thermal insulation layer 2 is less than 15%, and the thermal conductivity is not higher than 0.1W•m -1 •k -1 ; The pore size of the dense layer 3 is less than 5μm.

[0071] It should be noted that the process technology involved in the aforementioned preparation method of the present invention is not only limited to rigid thermal insulation material flat pieces, but also includes rigid thermal insulation materials with curved and special-shaped structures and their preparation, as well as improvements that can be obtained by technical personnel in this field without creative labor, all of which fall within the scope of protection of the present invention.

[0072] The present invention is further described below in conjunction with some specific embodiments.

[0073] Example 1

[0074] This embodiment provides a method for preparing a metallized rigid thermal insulation material for a patch antenna, specifically:

[0075] 1. Slurry preparation

[0076] Two different components of thermal insulation material matrix slurries are prepared, wherein the first matrix slurry is a mixture of chopped fibers, aluminum silica sol, a sintering aid, modified ceramic hollow ball powder, and deionized water; the second matrix slurry is a mixture of chopped fibers, aluminum silica sol, a sintering aid, and deionized water; the raw materials of the first matrix slurry and the second matrix slurry are mixed respectively, the pH is adjusted, and the mixture is evenly dispersed using a disperser to obtain the first matrix slurry and the second matrix slurry respectively.

[0077] The chopped fibers are a combination of quartz fibers, alumina fibers, and mullite fibers with a chopped length of 100 μm, and the weight ratio of the quartz fibers, alumina fibers, and mullite fibers is 1:1:1.

[0078] The solid content of the aluminum silica sol is 22wt%.

[0079] The sintering aid is boron oxide.

[0080] The modified ceramic hollow sphere powder is a hollow silica sphere powder and a hollow alumina sphere powder with an average diameter of 3 μm (mass ratio 1:1), which is obtained after being modified by silane coupling agent KH550 and silane coupling agent KH570. Specifically, silane coupling agent KH550 and silane coupling agent KH570 are added to an ethanol aqueous solution (ethanol volume concentration 10%) to obtain a modified liquid; then the hollow silica sphere powder and the hollow alumina sphere powder are added to the modified liquid for dispersion modification, and then dried to obtain the modified ceramic hollow sphere powder. The total amount of the silane coupling agent KH550 and the silane coupling agent KH570 is 3.5% of the total mass of the hollow sphere powder. The weight ratio of the silane coupling agent KH550 and the silane coupling agent KH570 is 1:1.

[0081] In the first matrix slurry, the mass fraction of chopped fibers is 7wt%, the mass fraction of aluminum silica sol is 5wt%, the mass fraction of sintering aid is 0.6wt%, the mass fraction of modified ceramic hollow sphere powder is 4.2wt%, and the balance is deionized water; in the second matrix slurry, the mass fraction of chopped fibers is 8.5wt%; the mass fraction of aluminum silica sol is 5wt%; the mass fraction of sintering aid is 0.6wt%, and the balance is deionized water.

[0082] 2. Filtration molding

[0083] First, pour the first matrix slurry in the mold and form the first layer of filter cake by vacuum filtration. When the slurry liquid level drops to the same level as the first layer of filter cake, slowly pour the second matrix slurry and form the second layer of filter cake by vacuum filtration until the filtration is completed. Then, keep warm and dry at 55°C for 11 hours. Keep warm and sinter at 1250°C for 3 hours to obtain a rigid insulation material blank with a high and low porosity gradient distribution.

[0084] The thickness of the first filter cake layer is controlled to 4 mm, and the thickness of the second filter cake layer is controlled to 12 mm. The second filter cake layer is formed by liquid phase connection between the second matrix slurry and the first matrix slurry, rather than forming the second filter cake layer after the first filter cake layer is filtrated.

[0085] 3. Densification treatment

[0086] The rigid thermal insulation material blank with high and low porosity gradient distribution obtained above was processed into a flat plate with a thickness of 3.02 mm, and a low-porosity thermal insulation layer with a thickness of 0.5 mm was retained; a nylon brush was used to evenly apply the densified slurry to the surface of the low-porosity thermal insulation layer of the rigid thermal insulation material, and the coating layer thickness was controlled to be 0.02 mm. After drying, it was polished flat with 1000 mesh sandpaper, and then a layer of strengthening agent was sprayed. Finally, it was sintered at 950°C in a muffle furnace for 3.5 hours to densify the surface of the rigid thermal insulation material to obtain a rigid thermal insulation material with a densified surface.

[0087] The densified slurry is prepared by ball milling and mixing modified ceramic powder, aluminum silica sol and boric acid for 1 hour; in the densified slurry, the modified ceramic powder accounts for 38% of the total mass of the densified slurry, and is composed of silicon oxide, magnesium fluoride, lithium oxide and aluminum oxide in a mass ratio of 4.5:1:1:2.5; silicon oxide and aluminum oxide are modified by silane coupling agent KH550 and silane coupling agent KH570, and the specific modification method is the same as the silane coupling agent modification method of the aforementioned modified ceramic hollow ball powder, and the total amount of silane coupling agent is 3.5% of the total mass of silicon oxide and aluminum oxide; the weight ratio of silane coupling agent KH550 and silane coupling agent KH570 is 1:1; the solid content of aluminum silica sol is 22wt%, accounting for 58% of the total mass of the densified slurry; the balance is boric acid (the boric acid concentration specification is 3wt%).

[0088] The reinforcing agent is a toluene solution of polysilazane, and the mass fraction of polysilazane in the reinforcing agent is 35%; the spraying amount of the reinforcing agent is 0.3g / 100cm 2 .

[0089] After testing, at the 10G test frequency, the dielectric constant of the surface densified rigid insulation material of this embodiment is 1.29, and the loss tangent is 8.8×10 -4 .

[0090] 4. Metallization treatment

[0091] The metal slurry spray coating is sprayed on the densified surface of the rigid thermal insulation material by spraying. The amount of material is controlled by the number of spraying times, which is controlled to be every 100cm 2The amount of metal slurry spray coating on the surface of the rigid thermal insulation material is 1.2g; then it is kept warm and dried at 95°C for 1h; and it is kept warm and sintered at 850°C for 20min to achieve a good combination of the metal coating and the rigid thermal insulation material.

[0092] The metal slurry spray coating is prepared by diluting a high-temperature resistant and anti-oxidative highly conductive metal slurry (silver slurry) with a diluent. The diluent is an ethanol solution of butyl carbitol; the mass fraction of butyl carbitol in the diluent is 12%; and the amount of the diluent is 30% of the total weight of the metal slurry spray coating.

[0093] The silver paste is a conventional commercial product, which is composed of silver powder, epoxy resin, glass powder and solvent, wherein the content of metal powder is 80wt%.

[0094] 5. Laser processing

[0095] The metal layer is finely processed into patch units by laser etching to obtain a metalized rigid thermal insulation material that can be used for patch antennas.

[0096] Among them, laser etching uses a 3D galvanometer to control the laser direction and uses picosecond laser for etching; the laser power is controlled to 4W, the linear speed is 450mm / s, and the number of etching times is 3 times.

[0097] This embodiment also provides a metallized rigid thermal insulation material for a patch antenna made by the above method. The adhesion level between the metal patch and the rigid thermal insulation material substrate is evaluated as level 0 by the ISO 2409 method.

[0098] Example 2

[0099] This embodiment provides a method for preparing a metallized rigid thermal insulation material for a patch antenna, specifically:

[0100] 1. Slurry preparation

[0101] Two different components of thermal insulation material matrix slurries are prepared, wherein the first matrix slurry is a mixture of chopped fibers, aluminum silica sol, a sintering aid, modified ceramic hollow ball powder, and deionized water; the second matrix slurry is a mixture of chopped fibers, aluminum silica sol, a sintering aid, and deionized water; the raw materials of the first matrix slurry and the second matrix slurry are mixed respectively, the pH value of the matrix slurry is adjusted, and the slurry is evenly dispersed using a disperser to obtain the first matrix slurry and the second matrix slurry respectively.

[0102] The chopped fibers are a combination of quartz fibers, alumina fibers, and mullite fibers with a chopped length of 120 μm, and the weight ratio of the quartz fibers, alumina fibers, and mullite fibers is 1:1:1.

[0103] The solid content of the aluminum silica sol is 22wt%.

[0104] The sintering aid is boron nitride.

[0105] The modified ceramic hollow sphere powder is a hollow silica sphere powder and a hollow alumina sphere powder with an average diameter of 4 μm (mass ratio 1:1), which is obtained after being modified by silane coupling agent KH550 and silane coupling agent KH570. Specifically, silane coupling agent KH550 and silane coupling agent KH570 are added to an ethanol aqueous solution (ethanol volume concentration 10%) to obtain a modified liquid; then the hollow silica sphere powder and the hollow alumina sphere powder are added to the modified liquid for dispersion modification, and then dried to obtain the modified ceramic hollow sphere powder. The total amount of the silane coupling agent KH550 and the silane coupling agent KH570 is 4% of the total mass of the hollow sphere powder. The weight ratio of the silane coupling agent KH550 and the silane coupling agent KH570 is 1.5:1.

[0106] In the first matrix slurry, the mass fraction of chopped fibers is 8wt%, the mass fraction of aluminum silica sol is 5wt%, the mass fraction of sintering aid is 0.7wt%, the mass fraction of modified ceramic hollow sphere powder is 4.5wt%, and the balance is deionized water; in the second matrix slurry, the mass fraction of chopped fibers is 9wt%; the mass fraction of aluminum silica sol is 5.5wt%; the mass fraction of sintering aid is 0.7wt%, and the balance is deionized water.

[0107] 2. Filtration molding

[0108] First, pour the first matrix slurry in the mold and form the first layer of filter cake by vacuum filtration. When the slurry liquid level drops to the same level as the first layer of filter cake, slowly pour the second matrix slurry and form the second layer of filter cake by vacuum filtration until the filtration is completed. Then, keep warm and dry at 55°C for 11 hours. Keep warm and sinter at 1250°C for 3.5 hours to obtain a rigid insulation material blank with a high and low porosity gradient distribution.

[0109] The thickness of the first filter cake layer is controlled to 4 mm, and the thickness of the second filter cake layer is controlled to 12 mm. The second filter cake layer is formed by liquid phase connection between the second matrix slurry and the first matrix slurry, rather than forming the second filter cake layer after the first filter cake layer is filtrated.

[0110] 3. Densification treatment

[0111] The rigid thermal insulation material blank with high and low porosity gradient distribution obtained above was processed into a flat plate with a thickness of 3.04 mm, and a low-porosity thermal insulation layer with a thickness of 0.5 mm was retained. The densified slurry was evenly coated on the surface of the low-porosity thermal insulation layer of the rigid thermal insulation material using a nylon brush, and the coating layer thickness was controlled to be 0.04 mm. After drying, it was polished flat with 1000 mesh sandpaper, and then a layer of strengthening agent was sprayed. Finally, it was sintered at 950°C in a muffle furnace for 3.5 hours to densify the surface of the rigid thermal insulation material to obtain a rigid thermal insulation material with a densified surface.

[0112] The densified slurry is prepared by ball milling and mixing modified ceramic powder, aluminum silica sol and boric acid for 1 hour; in the densified slurry, the modified ceramic powder accounts for 40% of the total mass of the densified slurry, and is composed of silicon oxide, magnesium fluoride, lithium oxide and aluminum oxide in a mass ratio of 4:1:1:2.7; wherein silicon oxide and aluminum oxide are modified by silane coupling agent KH550 and silane coupling agent KH570, and the specific modification method is the same as the silane coupling agent modification method of the aforementioned modified ceramic hollow ball powder, and the total amount of silane coupling agent is 4% of the total mass of silicon oxide and aluminum oxide; the weight ratio of silane coupling agent KH550 and silane coupling agent KH570 is 1.5:1; the solid content of aluminum silica sol is 22wt%, accounting for 56% of the total mass of the densified slurry; the balance is boric acid (the boric acid concentration specification is 3wt%).

[0113] The reinforcing agent is a toluene solution of polysilazane, and the mass fraction of polysilazane in the reinforcing agent is 35%; the spraying amount of the reinforcing agent is 0.4g / 100cm 2 .

[0114] After testing, at the 10G test frequency, the dielectric constant of the green body before being coated with the densified slurry in this embodiment (i.e., the green body with a thickness of 3.04 mm and a low-porosity thermal insulation layer thickness of 0.5 mm) is 1.28, and the loss tangent is 5.6×10 -4 After densification treatment, the dielectric constant of the surface densified rigid thermal insulation material with a dense layer is 1.31, and the loss tangent is 8.4×10 -4 It can be seen that the use of a specific densification process and densification slurry, under the aforementioned layer thickness conditions, will not significantly affect the overall dielectric properties of the rigid thermal insulation material; and can lay the foundation for subsequent metallization treatment and laser processing, and achieve the "air elevation" of the radiation element of the patch antenna through the densification layer.

[0115] 4. Metallization treatment

[0116] The metal slurry spray coating is sprayed on the densified surface of the rigid thermal insulation material by spraying. The amount of material is controlled by the number of spraying times, which is controlled to be every 100cm 2The amount of metal slurry spray coating on the surface of the rigid thermal insulation material is 1.2g; then it is kept warm and dried at 95°C for 1h; and it is kept warm and sintered at 850°C for 20min to achieve a good combination of the metal coating and the rigid thermal insulation material.

[0117] The metal slurry spray coating is prepared by diluting a high-temperature resistant and anti-oxidative highly conductive metal slurry (silver slurry) with a diluent. The diluent is an ethanol solution of butyl carbitol; the mass fraction of butyl carbitol in the diluent is 11%; and the amount of the diluent is 32% of the total weight of the metal slurry spray coating.

[0118] The silver paste is a conventional commercial product, which is composed of silver powder, epoxy resin, glass powder and solvent, wherein the content of metal powder is 80wt%.

[0119] 5. Laser processing

[0120] The metal layer is finely processed into patch units by laser etching to obtain a metalized rigid thermal insulation material that can be used for patch antennas.

[0121] Among them, laser etching uses a 3D galvanometer to control the laser direction and uses picosecond laser for etching; the laser power is controlled to 4W, the linear speed is 450mm / s, and the number of etching times is 3 times.

[0122] This embodiment also provides a metallized rigid thermal insulation material for a patch antenna made by the above method. The adhesion level between the metal patch and the rigid thermal insulation material substrate is evaluated as level 0 by the ISO 2409 method.

[0123] Example 3

[0124] This embodiment provides a method for preparing a metallized rigid thermal insulation material for a patch antenna, specifically:

[0125] 1. Slurry preparation

[0126] Two different components of thermal insulation material matrix slurries are prepared, wherein the first matrix slurry is a mixture of chopped fibers, aluminum silica sol, a sintering aid, modified ceramic hollow ball powder, and deionized water; the second matrix slurry is a mixture of chopped fibers, aluminum silica sol, a sintering aid, and deionized water; the raw materials of the first matrix slurry and the second matrix slurry are mixed respectively, the pH value of the matrix slurry is adjusted, and the slurry is evenly dispersed using a disperser to obtain the first matrix slurry and the second matrix slurry respectively.

[0127] The chopped fibers are a combination of quartz fibers, alumina fibers, and mullite fibers with a chopped length of 130 μm, and the weight ratio of the quartz fibers, alumina fibers, and mullite fibers is 1:2:1.

[0128] The solid content of the aluminum silica sol is 25wt%.

[0129] The sintering aid is boron oxide.

[0130] The modified ceramic hollow sphere powder is a hollow silica sphere powder and a hollow alumina sphere powder (mass ratio 1:2) with an average diameter of 5 μm, which is obtained after being modified by silane coupling agent KH550. Specifically, the silane coupling agent KH550 is added to an ethanol aqueous solution (ethanol volume concentration 10%) to obtain a modified liquid; then the hollow silica sphere powder and the hollow alumina sphere powder are added to the modified liquid for dispersion modification, and then dried to obtain the modified ceramic hollow sphere powder. The amount of the silane coupling agent KH550 is 4% of the total mass of the hollow sphere powder.

[0131] In the first matrix slurry, the mass fraction of chopped fibers is 9wt%, the mass fraction of aluminum silica sol is 6wt%, the mass fraction of sintering aid is 0.8wt%, the mass fraction of modified ceramic hollow sphere powder is 5wt%, and the balance is deionized water; in the second matrix slurry, the mass fraction of chopped fibers is 10wt%; the mass fraction of aluminum silica sol is 6.5wt%; the mass fraction of sintering aid is 0.8wt%, and the balance is deionized water.

[0132] 2. Filtration molding

[0133] First, pour the first matrix slurry in the mold and form the first layer of filter cake by vacuum filtration. When the slurry liquid level drops to the same level as the first layer of filter cake, slowly pour the second matrix slurry and form the second layer of filter cake by vacuum filtration until the filtration is completed. Then, keep warm and dry at 50°C for 12 hours. Keep warm and sinter at 1200°C for 4 hours to obtain a rigid insulation material blank with a high and low porosity gradient distribution.

[0134] The thickness of the first filter cake layer is controlled to 4.5 mm, and the thickness of the second filter cake layer is controlled to 10 mm. The second filter cake layer is formed by the liquid phase connection between the second matrix slurry and the first matrix slurry, rather than the second filter cake layer being formed after the first filter cake layer is filtrated.

[0135] 3. Densification treatment

[0136] The rigid thermal insulation material blank with high and low porosity gradient distribution obtained above was processed into a flat plate with a thickness of 3.10 mm, and a low-porosity thermal insulation layer with a thickness of 0.5 mm was retained. The densified slurry was evenly coated on the surface of the low-porosity thermal insulation layer of the rigid thermal insulation material using a nylon brush, and the coating layer thickness was controlled to be 0.06 mm. After drying, it was smoothed with 1000 mesh sandpaper, and then a layer of strengthening agent was sprayed. Finally, it was sintered at 850°C in a muffle furnace for 4 hours to densify the surface of the rigid thermal insulation material to obtain a rigid thermal insulation material with a densified surface.

[0137] Among them, the densification slurry is prepared by ball milling and mixing modified ceramic powder, aluminum silica sol and boric acid for 0.5h; in the densification slurry, the modified ceramic powder accounts for 35% of the total mass of the densification slurry, and is composed of silicon oxide, magnesium fluoride, lithium oxide and aluminum oxide in a mass ratio of 3:1:1:3; wherein, silicon oxide and aluminum oxide are modified by silane coupling agent KH550, and the specific modification method is the same as the silane coupling agent modification method of the aforementioned modified ceramic hollow ball powder, and the amount of silane coupling agent is 4% of the total mass of silicon oxide and aluminum oxide; the solid content of aluminum silica sol is 25wt%, accounting for 60% of the total mass of the densification slurry; the balance is boric acid (boric acid concentration specification is 5wt%).

[0138] The reinforcing agent is a polysilazane toluene solution, and the mass fraction of polysilazane in the reinforcing agent is 30%; the spraying amount of the reinforcing agent is 0.5g / 100cm 2 .

[0139] After testing, at the 10G test frequency, the dielectric constant of the surface densified rigid insulation material of this embodiment is 1.32, and the loss tangent is 1.4×10 -3 .

[0140] 4. Metallization treatment

[0141] The metal slurry spray coating is sprayed on the densified surface of the rigid thermal insulation material by spraying. The amount of material is controlled by the number of spraying times, which is controlled to be every 100cm 2 The amount of metal slurry spray coating on the surface of the rigid thermal insulation material is 1.0g; then it is kept warm and dried for 0.5h at 100℃; and it is kept warm and sintered for 30min at 750℃ to achieve a good combination of the metal coating and the rigid thermal insulation material.

[0142] The metal slurry spray coating is prepared by diluting a high-temperature resistant and anti-oxidative high-conductive metal slurry (silver slurry) with a diluent. The diluent is an ethanol solution of butyl carbitol; the mass fraction of butyl carbitol in the diluent is 15%; and the amount of the diluent is 25% of the total weight of the metal slurry spray coating.

[0143] The silver paste is a conventional commercial product, which is composed of silver powder, epoxy resin, glass powder and solvent, wherein the content of metal powder is 80wt%.

[0144] 5. Laser processing

[0145] The metal layer is finely processed into patch units by laser etching to obtain a metalized rigid thermal insulation material that can be used for patch antennas.

[0146] Among them, laser etching uses a 3D galvanometer to control the laser direction and uses picosecond laser for etching; the laser power is controlled to 3.5W, the linear speed is 400mm / s, and the number of etching times is 4 times.

[0147] This embodiment also provides a metallized rigid thermal insulation material for a patch antenna made by the above method. The adhesion level between the metal patch and the rigid thermal insulation material substrate is evaluated as level 0 by the ISO 2409 method.

[0148] Example 4

[0149] This embodiment provides a method for preparing a metallized rigid thermal insulation material for a patch antenna, specifically:

[0150] 1. Slurry preparation

[0151] Two different components of thermal insulation material matrix slurries are prepared, wherein the first matrix slurry is a mixture of chopped fibers, aluminum silica sol, a sintering aid, modified ceramic hollow ball powder, and deionized water; the second matrix slurry is a mixture of chopped fibers, aluminum silica sol, a sintering aid, and deionized water; the raw materials of the first matrix slurry and the second matrix slurry are mixed respectively, the pH value of the matrix slurry is adjusted, and the slurry is evenly dispersed using a disperser to obtain the first matrix slurry and the second matrix slurry respectively.

[0152] The chopped fibers are a combination of quartz fibers, alumina fibers, and mullite fibers with a chopped length of 80 μm, and the weight ratio of the quartz fibers, alumina fibers, and mullite fibers is 1:1:1.

[0153] The solid content of the aluminum silica sol is 20wt%.

[0154] The sintering aid is boron nitride.

[0155] The modified ceramic hollow sphere powder is an alumina hollow sphere powder with an average diameter of 3 μm, which is obtained after being modified by a silane coupling agent KH560. Specifically, the silane coupling agent KH560 is added to an ethanol aqueous solution (ethanol volume concentration of 10%) to obtain a modified solution; then the alumina hollow sphere powder is added to the modified solution for dispersion modification, and then dried to obtain a modified ceramic hollow sphere powder. The amount of the silane coupling agent used is 5% of the total mass of the hollow sphere powder.

[0156] In the first matrix slurry, the mass fraction of chopped fibers is 10wt%, the mass fraction of aluminum silica sol is 7wt%, the mass fraction of sintering aid is 1.0wt%, the mass fraction of modified ceramic hollow sphere powder is 5wt%, and the balance is deionized water; in the second matrix slurry, the mass fraction of chopped fibers is 10wt%; the mass fraction of aluminum silica sol is 7wt%; the mass fraction of sintering aid is 1.0wt%, and the balance is deionized water.

[0157] 2. Filtration molding

[0158] First, pour the first matrix slurry in the mold and form the first layer of filter cake by vacuum filtration. When the slurry liquid level drops to the same level as the first layer of filter cake, slowly pour the second matrix slurry and form the second layer of filter cake by vacuum filtration until the filtration is completed. Then, keep warm and dry at 60°C for 8 hours. Keep warm and sinter at 1300°C for 2 hours to obtain a rigid insulation material blank with a high and low porosity gradient distribution.

[0159] The thickness of the first filter cake layer is controlled to 5 mm, and the thickness of the second filter cake layer is controlled to 15 mm; the second filter cake layer is formed by the liquid phase connection between the second matrix slurry and the first matrix slurry, rather than the second filter cake layer being formed after the first filter cake layer is filtrated.

[0160] 3. Densification treatment

[0161] The rigid thermal insulation material blank with high and low porosity gradient distribution obtained above was processed into a flat plate with a thickness of 3.10 mm, and a low-porosity thermal insulation layer with a thickness of 0.5 mm was retained. The densified slurry was evenly coated on the surface of the low-porosity thermal insulation layer of the rigid thermal insulation material using a nylon brush, and the coating layer thickness was controlled to be 0.08 mm. After drying, it was smoothed with 900-mesh sandpaper, and then a layer of strengthening agent was sprayed. Finally, it was sintered at 1000°C in a muffle furnace for 2 hours to densify the surface of the rigid thermal insulation material to obtain a rigid thermal insulation material with a densified surface.

[0162] Among them, the densification slurry is prepared by ball milling and mixing modified ceramic powder, aluminum silica sol and boric acid for 0.5h; in the densification slurry, the modified ceramic powder accounts for 45% of the total mass of the densification slurry, and is composed of silicon oxide, magnesium fluoride, lithium oxide and aluminum oxide in a mass ratio of 5:1:1:2; wherein silicon oxide and aluminum oxide are modified by silane coupling agent KH560, and the specific modification method is the same as the silane coupling agent modification method of the aforementioned modified ceramic hollow ball powder, and the amount of silane coupling agent KH560 is 5% of the total mass of silicon oxide and aluminum oxide; the solid content of aluminum silica sol is 20wt%, accounting for 50% of the total mass of the densification slurry; the balance is boric acid (boric acid concentration specification is 3wt%).

[0163] The reinforcing agent is a xylene solution of polysiloxane, and the mass fraction of polysiloxane in the reinforcing agent is 35%; the spraying amount of the reinforcing agent is 0.4g / 100cm 2 .

[0164] After testing, at the 10G test frequency, the dielectric constant of the surface densified rigid insulation material of this embodiment is 1.32, and the loss tangent is 4.6×10 -3 .

[0165] 4. Metallization treatment

[0166] The metal slurry spray coating is sprayed on the densified surface of the rigid thermal insulation material by spraying. The amount of material is controlled by the number of spraying times, which is controlled to be every 100cm 2 The amount of metal slurry spray coating on the surface of the rigid thermal insulation material is 1.5g; then it is kept warm and dried for 0.5h at 100℃; and sintered for 15min at 900℃ to achieve a good combination of the metal coating and the rigid thermal insulation material.

[0167] The metal slurry spray coating is prepared by diluting a high-temperature resistant and anti-oxidation highly conductive metal slurry (silver slurry) with a diluent. The diluent is an ethanol solution of butyl carbitol; the mass fraction of butyl carbitol in the diluent is 8%; and the amount of the diluent is 35% of the total weight of the metal slurry spray coating.

[0168] The silver paste is a conventional commercial product, which is composed of silver powder, epoxy resin, glass powder and solvent, wherein the content of metal powder is 80wt%.

[0169] 5. Laser processing

[0170] The metal layer is finely processed into patch units by laser etching to obtain a metalized rigid thermal insulation material that can be used for patch antennas.

[0171] Among them, laser etching uses a 3D galvanometer to control the laser direction and uses picosecond laser for etching; the laser power is controlled to 2W, the linear speed is 500mm / s, and the number of etching times is 4 times.

[0172] This embodiment also provides a metallized rigid thermal insulation material for a patch antenna made by the above method. The adhesion level between the metal patch and the rigid thermal insulation material substrate is evaluated as level 0 by the ISO 2409 method.

[0173] Example 5

[0174] This embodiment provides a method for preparing a metallized rigid thermal insulation material for a patch antenna, specifically:

[0175] 1. Slurry preparation

[0176] Two different components of thermal insulation material matrix slurries are prepared, wherein the first matrix slurry is a mixture of chopped fibers, aluminum silica sol, a sintering aid, modified ceramic hollow ball powder, and deionized water; the second matrix slurry is a mixture of chopped fibers, aluminum silica sol, a sintering aid, and deionized water; the raw materials of the first matrix slurry and the second matrix slurry are mixed respectively, the pH value of the matrix slurry is adjusted, and the slurry is evenly dispersed using a disperser to obtain the first matrix slurry and the second matrix slurry respectively.

[0177] The chopped fibers are a combination of quartz fibers, alumina fibers, and mullite fibers with a chopped length of 200 μm, and the weight ratio of the quartz fibers, alumina fibers, and mullite fibers is 1:1:2.

[0178] The solid content of the aluminum silica sol is 25wt%.

[0179] The sintering aids are boron oxide and boron nitride; the mass ratio of boron oxide to boron nitride is 1:1.

[0180] The modified ceramic hollow sphere powder is a hollow silica sphere powder and a hollow alumina sphere powder with an average diameter of 3 μm (mass ratio 1:1), which is obtained after being modified by silane coupling agent KH560 and silane coupling agent KH570. Specifically, silane coupling agent KH560 and silane coupling agent KH570 are added to an ethanol aqueous solution (ethanol volume concentration 10%) to obtain a modified liquid; then the hollow silica sphere powder and the hollow alumina sphere powder are added to the modified liquid for dispersion modification, and then dried to obtain the modified ceramic hollow sphere powder. The total amount of the silane coupling agent KH560 and the silane coupling agent KH570 is 2% of the total mass of the hollow sphere powder. The weight ratio of the silane coupling agent KH560 and the silane coupling agent KH570 is 1:1.

[0181] In the first matrix slurry, the mass fraction of chopped fibers is 5wt%, the mass fraction of aluminum silica sol is 2wt%, the mass fraction of sintering aid is 0.5wt%, the mass fraction of modified ceramic hollow sphere powder is 3wt%, and the balance is deionized water; in the second matrix slurry, the mass fraction of chopped fibers is 8wt%, the mass fraction of aluminum silica sol is 2wt%, the mass fraction of sintering aid is 0.5wt%, and the balance is deionized water.

[0182] 2. Filtration molding

[0183] First, pour the first matrix slurry in the mold and form the first layer of filter cake by vacuum filtration. When the slurry liquid level drops to the same level as the first layer of filter cake, slowly pour the second matrix slurry and form the second layer of filter cake by vacuum filtration until the filtration is completed. Then, keep warm and dry at 60°C for 12 hours. Keep warm and sinter at 1300°C for 3.5 hours to obtain a rigid insulation material blank with a high and low porosity gradient distribution.

[0184] The thickness of the first filter cake layer is controlled to 3 mm, and the thickness of the second filter cake layer is controlled to 11 mm. The second filter cake layer is formed by liquid connection between the second matrix slurry and the first matrix slurry, rather than after the first filter cake layer is filtered out and then the second filter cake layer is formed.

[0185] 3. Densification treatment

[0186] The rigid thermal insulation material blank with high and low porosity gradient distribution obtained above was processed into a flat plate with a thickness of 3.08 mm, and a low-porosity thermal insulation layer with a thickness of 0.5 mm was retained. The densified slurry was evenly coated on the surface of the low-porosity thermal insulation layer of the rigid thermal insulation material using a nylon brush, and the coating layer thickness was controlled to be 0.1 mm. After drying, it was smoothed with 800-mesh sandpaper, and then a layer of strengthening agent was sprayed. Finally, it was sintered at 900°C in a muffle furnace for 3 hours to densify the surface of the rigid thermal insulation material to obtain a rigid thermal insulation material with a densified surface.

[0187] Among them, the densification slurry is prepared by ball milling and mixing modified ceramic powder, aluminum silica sol and boric acid for 0.75h; in the densification slurry, the modified ceramic powder accounts for 40% of the total mass of the densification slurry, and is composed of silicon oxide, magnesium fluoride, lithium oxide and aluminum oxide in a mass ratio of 4.5:1:1:2.2; wherein, silicon oxide and aluminum oxide are modified by silane coupling agent KH560 and silane coupling agent KH570, and the specific modification method is the same as the silane coupling agent modification method of the aforementioned modified ceramic hollow ball powder, and the total amount of silane coupling agent KH560 and silane coupling agent KH570 is 4% of the total mass of silicon oxide and aluminum oxide; the solid content of aluminum silica sol is 25wt%, accounting for 55% of the total mass of the densification slurry; the balance is boric acid (boric acid concentration specification is 5wt%).

[0188] The reinforcing agent is a xylene solution of polysilazane, and the mass fraction of polysilazane in the reinforcing agent is 40%; the spraying amount of the reinforcing agent is 0.4g / 100cm 2 .

[0189] After testing, at the 10G test frequency, the dielectric constant of the surface densified rigid insulation material of this embodiment is 1.35, and the loss tangent is 5.2×10 -3 .

[0190] 4. Metallization treatment

[0191] The metal slurry spray coating is sprayed on the densified surface of the rigid thermal insulation material by spraying. The amount of material is controlled by the number of spraying times, which is controlled to be every 100cm 2 The amount of metal slurry spray coating on the surface of the rigid thermal insulation material is 1.0g; then it is kept warm and dried at 85°C for 1h; and it is kept warm and sintered at 750°C for 15min to achieve a good combination of the metal coating and the rigid thermal insulation material.

[0192] The metal slurry spray coating is prepared by diluting a high-temperature resistant and anti-oxidative high-conductive metal slurry (silver slurry) with a diluent. The diluent is an ethanol solution of butyl carbitol; the mass fraction of butyl carbitol in the diluent is 8%; and the amount of the diluent is 25% of the total weight of the metal slurry spray coating.

[0193] The silver paste is a conventional commercial product, which is composed of silver powder, epoxy resin, glass powder and solvent, wherein the content of metal powder is 80wt%.

[0194] 5. Laser processing

[0195] The metal layer is finely processed into patch units by laser etching to obtain a metalized rigid thermal insulation material that can be used for patch antennas.

[0196] Among them, laser etching uses a 3D galvanometer to control the laser direction and uses picosecond laser for etching; the laser power is controlled to 4W, the linear speed is 300mm / s, and the number of etching times is 2 times.

[0197] This embodiment also provides a metallized rigid thermal insulation material for a patch antenna made by the above method. The adhesion level between the metal patch and the rigid thermal insulation material substrate is evaluated as level 0 by the ISO 2409 method.

[0198] According to the test, in the metallized rigid thermal insulation materials for patch antennas of Examples 1-5, the transition of the matrix from high porosity to low porosity structure is achieved by controlling the molding of the rigid thermal insulation materials. The porosity of the high porosity thermal insulation layer is greater than 90%, and the thermal conductivity is not higher than 0.06 W•m -1 •k -1 The porosity of the low-porosity insulation layer is less than 15%, and the thermal conductivity is no higher than 0.1W•m -1 •k -1 . By applying a special slurry to achieve surface densification, the adhesion of the metal coating to the thermal insulation material, as well as its surface consistency and microscopic continuity, the pore size of the dense layer is less than 5μm, and the adhesion level of the metal patch to the rigid thermal insulation material substrate is level 0. By designing the gradient structure of the rigid wave-transmitting thermal insulation material and performing surface densification treatment, the metal coating can be prepared on the loose and porous rigid thermal insulation material in a breakthrough manner; and the problem of introducing low thermal conductivity ceramic hollow sphere powder to affect the thermal conductivity of the rigid thermal insulation material, and the problem of densification treatment and the dense layer prepared by it affecting the overall dielectric properties of the rigid thermal insulation material can be effectively avoided; the low dielectric properties and temperature resistance and thermal insulation properties of the rigid thermal insulation material can be effectively combined, and the loose and porous structural limitations of the rigid thermal insulation material can be effectively avoided. Fine metal units can be prepared on the surface of the rigid thermal insulation and wave-transmitting material to achieve the "air elevation" of the radiation array element of the patch antenna.

[0199] Unless otherwise specified, all percentages used in the present invention are by mass.

[0200] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a metallized rigid thermal insulation material for a patch antenna, characterized in that: The method consists of the following steps: slurry preparation, filtration molding, densification treatment, metallization treatment, and laser processing; The method for preparing the slurry is as follows: short-cut fibers, aluminum silica sol, sintering aid, modified ceramic hollow ball powder and deionized water are uniformly mixed to obtain a first matrix slurry; short-cut fibers, aluminum silica sol, sintering aid and deionized water are uniformly mixed to obtain a second matrix slurry; The modified ceramic hollow sphere powder is hollow silicon oxide sphere powder and / or hollow aluminum oxide sphere powder modified by a silane coupling agent; The filtration molding method comprises pouring a first matrix slurry in a mold, vacuum filtration to form a first layer of filter cake, pouring a second matrix slurry when the slurry liquid level drops to the same level as the first layer of filter cake, and vacuum filtration to form a second layer of filter cake; drying and sintering to obtain a rigid thermal insulation material blank with a high-low porosity gradient distribution; The densification treatment method is to process the rigid thermal insulation material blank with high and low porosity gradient distribution into a predetermined thickness, apply the densification slurry to the surface of the low-porosity thermal insulation layer of the rigid thermal insulation material blank, spray a reinforcing agent after drying, and sinter to obtain a rigid thermal insulation material with a densified surface layer; The densified slurry is uniformly prepared by ball milling modified ceramic powder, aluminum silica sol and boric acid; The metallization treatment method is to spray a metal slurry spray coating onto the densified surface of the rigid thermal insulation material, and obtain a rigid thermal insulation material with a metal coating after drying and sintering; The laser processing method comprises: performing laser etching on the metal coating of the rigid heat-insulating material to obtain the metallized rigid heat-insulating material that can be used for the patch antenna.

2. The method for preparing the metallized rigid thermal insulation material for patch antenna according to claim 1, characterized in that: In the first matrix slurry, the mass fraction of chopped fibers is 5-10wt%, the mass fraction of aluminum silica sol is 2-7wt%, the mass fraction of sintering aid is 0.5-1.0wt%, the mass fraction of modified ceramic hollow ball powder is 3-5wt%, and the balance is deionized water; In the second matrix slurry, the mass fraction of chopped fibers is 8-10wt%; the mass fraction of aluminum silica sol is 2-7wt%; the mass fraction of sintering aid is 0.5-1.0wt%, and the balance is deionized water.

3. The method for preparing the metallized rigid thermal insulation material for patch antenna according to claim 1, characterized in that: In the slurry preparation, the chopped fibers are a combination of quartz fibers, alumina fibers, and mullite fibers with a length of 20-250 μm; the solid content of the aluminum silica sol is 20-25 wt %; and the sintering aid is boron oxide and / or boron nitride; The silane coupling agent used in the modified ceramic hollow ball powder is at least one of the following: silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570.

4. The method for preparing the metallized rigid thermal insulation material for patch antenna according to claim 1, characterized in that: In the suction filtration molding, the thickness of the first layer of filter cake is controlled to 3-5 mm, and the thickness of the second layer of filter cake is controlled to 5-15 mm; The sintering temperature is 1200-1300°C and the sintering time is 2-4h.

5. The method for preparing the metallized rigid thermal insulation material for patch antenna according to claim 1, characterized in that: In the densification process, the rigid thermal insulation material blank with high and low porosity gradient distribution is processed into a thickness of 3-5 mm, and a low-porosity thermal insulation layer with a thickness of 0.5-0.8 mm is retained; The coating layer thickness of the densified slurry is 0.02-0.1 mm.

6. The method for preparing the metallized rigid thermal insulation material for patch antenna according to claim 1, characterized in that: In the densified slurry, the modified ceramic powder accounts for 30-45% of the total mass of the densified slurry; the aluminum silica sol accounts for 50-65% of the total mass of the slurry; and the balance is boric acid; The modified ceramic powder is composed of silicon oxide, magnesium fluoride, lithium oxide and aluminum oxide in a mass ratio of 3-5:1:1:2-3; the silicon oxide is obtained by modification with a silane coupling agent; the aluminum oxide is obtained by modification with a silane coupling agent; The solid content of aluminum silica sol is 20-25wt%; The mass concentration of boric acid is 3-5wt%; The strengthening agent is a toluene or xylene solution of polysilazane or polysiloxane, and the mass fraction of polysilazane or polysiloxane in the strengthening agent is 30-40%.

7. The method for preparing the metallized rigid thermal insulation material for patch antenna according to claim 1, characterized in that: During the metallization treatment, the metal slurry spray coating is controlled to be at a rate of 100 cm 2 The spraying amount of the densified surface of the rigid insulation material is 1.0-1.5g; The metal slurry spray coating is prepared by diluting highly conductive metal slurry with a diluent; the diluent is an ethanol or propanol solution of butyl carbitol or terpineol.

8. The method for preparing the metallized rigid thermal insulation material for patch antenna according to claim 7, characterized in that: The highly conductive metal slurry is one of the following: silver slurry, gold slurry, platinum slurry, silver-palladium alloy slurry; The mass fraction of butyl carbitol or terpineol in the diluent is 8-15%; The amount of the diluent is 25-35% of the total weight of the metal slurry spray coating.

9. The method for preparing the metallized rigid thermal insulation material for patch antenna according to claim 1, characterized in that: In the laser processing, picosecond laser is used for laser etching; the laser power is controlled to be 2-5W, the linear speed is 300-500mm / s, and the etching times are 2-4 times.

10. A metallized rigid thermal insulation material for a patch antenna prepared by the preparation method according to any one of claims 1 to 9, characterized in that: The following are arranged in sequence: a high-porosity heat-insulating layer (1), a low-porosity heat-insulating layer (2), a dense layer (3), and a metal patch layer (4).

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