Broadband heat-insulating ceramic wave-absorbing material and preparation method and infrared stealth application thereof

Abstract

The invention discloses a broadband heat-insulating ceramic wave-absorbing material and a preparation method and infrared stealth application thereof, and belongs to the technical field of functional materials. The wave-absorbing material comprises a polymer blank which is subjected to photocuring 3D printing through polymer precursor slurry and is subjected to pyrolysis ceramization forming, and the polymer precursor slurry comprises photosensitive polyborosiloxane, hollow glass microspheres, an acrylate cross-linking agent and an initiator. The hollow glass microspheres are doped in the polymer precursor slurry containing the photosensitive polysiloxane, and the 3D printing coupling pyrolysis ceramic forming technology is combined, so that controllable forming of the structure and function integrated ceramic wave-absorbing material is effectively achieved, the preparation is simple, the cost is low, and the formed composite ceramic structure can be accurately controlled; meanwhile, the prepared wave-absorbing material has the advantages of multiple reflection loss mechanisms, impedance matching adjustment, wave-absorbing frequency band widening, good heat insulation performance and the like, and has good electromagnetic and infrared compatible stealth performance.

Description

Technical Field

[0001] This application belongs to the technical field of microwave absorbing materials, and particularly relates to a broadband heat-insulating ceramic microwave absorbing material, its preparation method, and infrared stealth application. Background Art

[0002] Ceramic microwave absorbing materials have the advantages of high temperature resistance, high strength, low creep, and corrosion resistance, and can show great superiority when used for infrared stealth. However, the forming temperature of traditional ceramic microwave absorbing materials is generally high (>1600°C), and the industrialization prospect is not good. Therefore, the design of high-performance ceramic microwave absorbing materials that are easy to form has attracted much attention.

[0003] At present, relevant reports have disclosed the technical strategy of polymer-derived ceramics, that is, after designing and synthesizing a polymer with a specific structure, it is pyrolyzed at 800-1400°C to form a ceramic microwave absorbing material, which has the advantages of low pyrolysis temperature and clear composition, and has good prospects in fields such as micro-devices and stealth coatings.

[0004] However, the existing polymer-derived ceramic technology still has deficiencies. For example, the volume shrinkage that occurs during the ceramization transformation is likely to cause cracks or structural collapse, resulting in great technical difficulties in preparing a structure-function integrated ceramic microwave absorbing material and restricting large-scale production. Summary of the Invention

[0005] This application discloses a broadband heat-insulating ceramic microwave absorbing material, its preparation method, and infrared stealth application. By setting a polymer precursor slurry with a specific composition combination and combining 3D printing and pyrolytic ceramization forming technology, the controllable preparation of a structure-function integrated ceramic microwave absorbing material is effectively realized.

[0006] To achieve the above object, the technical solution adopted in this application is:

[0007] In the first aspect of this application, a broadband heat-insulating ceramic microwave absorbing material is provided. The broadband heat-insulating ceramic microwave absorbing material includes a composite ceramic formed by photocuring 3D printing a polymer green body through the following polymer precursor slurry and subjecting the polymer green body to pyrolytic ceramization;

[0008] Among them, the polymer precursor slurry includes:

[0009] (1) Photosensitive polyborosiloxane;

[0010] (2) Hollow glass microspheres;

[0011] (3) Acrylate cross-linking agent;

[0012] (4) Initiator.

[0013] According to the broadband heat-insulating ceramic wave-absorbing material of the present disclosure, the hollow glass microspheres are selected as silicon borate hollow glass microspheres, with a particle size of 5-40 μm and a wall thickness of 0.5-3 μm.

[0014] According to the broadband heat-insulating ceramic wave-absorbing material of the present disclosure, the content of the hollow glass microspheres is 20-80 wt% of the sum of the masses of the photosensitive polyborosiloxane, acrylate cross-linking agent, and photoinitiator.

[0015] According to the broadband heat-insulating ceramic wave-absorbing material of the present disclosure, the acrylate cross-linking agent is any one of pentaerythritol tetraacrylate, 1,6-hexanediol diacrylate, and trimethylolpropane triacrylate, and its content is 5-30 wt% of the mass of the photosensitive polyborosiloxane.

[0016] According to the broadband heat-insulating ceramic wave-absorbing material of the present disclosure, the initiator is selected as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and its content is 1-6 wt% of the sum of the masses of the photosensitive polyborosiloxane and acrylate cross-linking agent.

[0017] The second aspect of the present application also provides a preparation method of the broadband heat-insulating ceramic wave-absorbing material of the present invention, which includes the following steps:

[0018] Prepare photosensitive polyborosiloxane;

[0019] Add an acrylate cross-linking agent, an initiator, and hollow glass microspheres to the photosensitive polyborosiloxane and mix evenly to obtain a polymer precursor slurry;

[0020] Photocure the polymer precursor slurry by 3D printing to form a polymer green body, and perform pyrolytic ceramization treatment on the polymer green body to obtain the broadband heat-insulating ceramic wave-absorbing material.

[0021] According to the preparation method of the present disclosure, the preparation of the photosensitive polyborosiloxane includes:

[0022] Provide a precursor solution containing methylboronic acid, 3-(methacryloyloxy)propyltrimethoxysilane, diphenyldimethoxysilane, dimethoxymethylvinylsilane, and trimethylmethoxysilane;

[0023] Place the precursor solution at a temperature of 60-120°C and stir for 3-10 h, and perform vacuum rotary evaporation drying on the reaction product to obtain photosensitive polyborosiloxane.

[0024] According to the preparation method of the present disclosure, the molar ratio of methylboronic acid, 3-(methacryloyloxy)propyltrimethoxysilane, diphenyldimethoxysilane, dimethoxymethylvinylsilane, and trimethylmethoxysilane is (1 to 1.5):(0.1 to 0.4):(0.05 to 0.4):(0.4 to 1):(0.01 - 0.05).

[0025] According to the preparation method of the present disclosure, the parameter settings of the photocuring 3D printing include:

[0026] The irradiation intensity of the light source is 5 to 15 mW / cm 2 , and the exposure duration for a single layer is 2 to 15 s;

[0027] The moving speed of the squeegee is 50%; and,

[0028] The layer thickness of the printed slice is 10 to 100 μm.

[0029] The third aspect of the present application also provides the application of the broadband heat-insulating ceramic absorbing material of the present invention in the field of electromagnetic and infrared compatible stealth.

[0030] Compared with the prior art, the advantages or beneficial effects of the present application at least include:

[0031] By setting a polymer precursor slurry containing the above components and combining 3D printing with coupled pyrolysis ceramization conversion molding technology, the controllable preparation of a structure-functional integrated ceramic absorbing material is effectively achieved. The operation is simple, the cost is low, and the formed composite ceramic structure can be precisely controlled. Specifically, through the combined design of the components contained in the polymer precursor slurry and the structure-functional integrated cooperation of the 3D printing complex precise structure regulation and pyrolysis ceramization coupling molding strategy, multiple reflection loss mechanisms and good impedance matching can be given to the formed composite ceramic, enabling the formed composite ceramic to have excellent absorbing properties. At the same time, the absorption bandwidth of the formed composite ceramic can be broadened and the density can be reduced, making the composite ceramic absorbing material have the characteristics of low density and wide absorption frequency band. In addition, the heat-insulating performance of the formed composite ceramic can be enhanced, achieving the effect of reducing infrared signals and improving the comprehensive stealth performance, and having broad prospects in the field of electromagnetic / infrared compatible stealth. Description of the Drawings

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments recorded in the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1Physical photos of the coaxial ring polymer green body with 60wt% HGM content and the corresponding coaxial ring broadband heat-insulating ceramic microwave absorbing material provided by this application;

[0034] Figure 2 Dielectric property diagrams of the coaxial ring broadband heat-insulating ceramic microwave absorbing materials with different HGM contents provided by this application;

[0035] Figure 3 Impedance matching diagrams of the coaxial ring broadband heat-insulating ceramic microwave absorbing materials with different HGM contents provided by this application;

[0036] Figure 4 Microwave absorption property diagrams within 2 - 18 GHz of the coaxial ring broadband heat-insulating ceramic microwave absorbing materials prepared with different HGM contents and different pyrolysis temperatures provided by this application;

[0037] Figure 5 Thermal conductivity diagrams of the coaxial ring broadband heat-insulating ceramic microwave absorbing materials with different HGM contents provided by this application;

[0038] Figure 6 High-temperature infrared thermal imaging pictures of the coaxial ring broadband heat-insulating ceramic microwave absorbing material with 60wt% HGM content provided by this application;

[0039] Figure 7 Physical photos of the Schwarz P-structured polymer green body with 60wt% HGM content and the corresponding Schwarz P-structured broadband heat-insulating ceramic microwave absorbing material provided by this application;

[0040] Figure 8 Microwave absorption property diagrams within 2 - 18 GHz of the Schwarz P-structured broadband heat-insulating ceramic microwave absorbing materials with different HGM contents provided by this application. Detailed implementation manners

[0041] Next, the technical solutions in the embodiments of this application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

[0042] In the following description of this disclosure, the term "and / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: the case of A alone, the case of B alone, and the case of both A and B existing simultaneously. Where A and B may be singular or plural.

[0043] In the following description of the present disclosure, the term "at least one" means one or more; "a plurality" means two or more. "At least one of the following" or similar descriptions all refer to any combination of these items, including any combination of single item or plural items. For example, "at least one of A, B or C", or, "at least one of A, B and C" both mean one of A, B, C, or A + B, or A + C, or B + C, or A + B + C, where A, B, C can be single or multiple respectively.

[0044] In the following description of the present disclosure, the sequence numbers do not mean the order of execution, and some or all steps can be executed in parallel or successively. The execution order of each process should be specifically determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0045] In the following description of the present disclosure, the numerical range should be understood as specifically disclosing each intermediate value between the upper and lower limits of the range. The intermediate value within any stated value or stated range and each smaller range between any other stated value or intermediate value within the stated range are also included in the present application. The upper and lower limits of these smaller ranges can be independently included or excluded within the range.

[0046] Unless otherwise specified, the technical / scientific terms used in the present disclosure have the same meaning as commonly understood by those of ordinary skill in the art. Although only preferred methods and materials are described in the present application, any methods and materials similar or equivalent to those described in the present disclosure can also be used in the implementation or testing of the present disclosure. All documents mentioned in the present disclosure are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of the present disclosure shall prevail.

[0047] In a first aspect, an embodiment of the present invention provides a broadband heat-insulating ceramic wave-absorbing material, which includes a composite ceramic formed by photocuring a 3D printed polymer green body through the following polymer precursor slurry and subjecting the polymer green body to pyrolytic ceramization;

[0048] Wherein, the polymer precursor slurry includes:

[0049] (1) Photosensitive polyborosiloxane;

[0050] (2) Hollow glass microspheres;

[0051] (3) Acrylate crosslinking agent;

[0052] (4) Initiator.

[0053] It should be noted that the polymer green body can be of various simple or complex structures, such as a simple coaxial ring structure or a complex Schwarz P structure; the pyrolytic ceramization refers to the process of pyrolyzing the polymer green body to generate ceramics.

[0054] Combined with the above, the present invention effectively achieves the controllable preparation of the structural-functional integrated ceramic wave-absorbing material by setting the polymer precursor slurry containing the above components and combining the 3D printing coupled with pyrolytic ceramization transformation molding technology. The operation is simple, the cost is low, and the formed composite ceramic structure can be precisely controlled, which is convenient for large-scale industrial production. Specifically, by setting the combination of the effective components contained in the polymer precursor slurry and the 3D printing complex structure coupled with pyrolytic ceramization molding technology, the structural-functional integrated composite ceramic wave-absorbing material is precisely constructed. First, it can endow the formed composite ceramic with multiple reflection loss mechanisms and good impedance matching, effectively improving the wave-absorbing ability of the composite ceramic wave-absorbing material; second, it can broaden the absorption bandwidth of the formed composite ceramic and reduce the density, so that the composite ceramic wave-absorbing material has the characteristics of low density and wide absorption frequency band; third, it can also enhance the heat insulation performance of the formed composite ceramic, reduce the infrared signal and improve the comprehensive stealth performance, and has broad prospects for electromagnetic / infrared compatible stealth fields.

[0055] In a specific example of the present disclosure, the hollow glass microspheres are preferably commercially available silicon borate hollow glass microspheres, more preferably silicon borate hollow glass microspheres with a particle size of 5-40 μm and a wall thickness of 0.5-3 μm. For example, 3M™ Hollow Glass Microspheres iM30K are used in the embodiments of the present invention.

[0056] In a specific example of the present disclosure, the content of the hollow glass microspheres is preferably 20-80 wt% of the sum of the masses of the photosensitive polyborosiloxane, acrylate crosslinking agent and photoinitiator, preferably 40-70 wt%, more preferably 60 wt%, so that the formed composite ceramic has the minimum reflection loss, the best absorption bandwidth and the lowest thermal conductivity, and thus is better used for infrared stealth.

[0057] In a specific example of the present disclosure, the acrylate crosslinking agent is any one of pentaerythritol tetraacrylate, 1,6-hexanediol diacrylate, and trimethylolpropane triacrylate, and its content is 5-30 wt% of the mass of the photosensitive polyborosiloxane, preferably 10 wt%.

[0058] In a specific example of the present disclosure, the initiator is selected as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and its content is 1-6 wt% of the sum of the masses of the photosensitive polyborosiloxane and acrylate crosslinking agent, preferably 4 wt%.

[0059] Second aspect, the embodiments of the present application also disclose a preparation method of the broadband heat-insulating ceramic absorbing material of the present invention, and its steps include:

[0060] Prepare photosensitive polyborosiloxane;

[0061] Add an acrylate crosslinking agent, an initiator and hollow glass microspheres to the photosensitive polyborosiloxane and mix evenly to obtain a polymer precursor slurry;

[0062] Photocure the polymer precursor slurry by 3D printing to form a polymer green body, and perform pyrolytic ceramization treatment on the polymer green body to obtain the broadband heat-insulating ceramic absorbing material.

[0063] In a specific example of the present disclosure, the preparation of the photosensitive polyborosiloxane includes:

[0064] Provide a precursor solution containing methylboronic acid, 3-(methacryloyloxy)propyltrimethoxysilane, diphenyldimethoxysilane, dimethoxymethylvinylsilane and trimethylmethoxysilane;

[0065] Place the precursor solution at a temperature of 60-120 °C and stir for 3-10 h, and perform vacuum rotary evaporation drying on the reaction product to obtain photosensitive polyborosiloxane.

[0066] It should be noted that the present application has no special limitation on the specific parameters of the stirring reaction of the above precursor solution, and any value within its range can be used, such as 60 °C / 10 h, 70 °C / 9 h, 90 °C / 8 h, 100 °C / 6 h, 120 °C / 3 h, etc.

[0067] In a specific example of the present disclosure, the molar ratio of the methylboronic acid, 3-(methacryloyloxy)propyltrimethoxysilane, diphenyldimethoxysilane, dimethoxymethylvinylsilane and trimethylmethoxysilane is (1-1.5):(0.1-0.4):(0.05-0.4):(0.4-1):(0.01-0.05), such as 1.17:0.2:0.1:0.7:0.02, etc.

[0068] Those skilled in the art understand that the precursor solution in the preferred example of the present disclosure should be prepared in an inert atmosphere of anhydrous and oxygen-free. The present application has no special limitation on the solvent for preparing the precursor solution, and it can be reasonably selected according to the properties of the polymer precursor. For example, 1,4-dioxane is selected in the example of the present invention.

[0069] In a specific example of the present disclosure, the parameters of the photocuring 3D printing are preferably:

[0070] Light source irradiation intensity 5-15 mW / cm 2, the single-layer exposure time is 2 to 15 s;

[0071] the moving speed of the squeegee is 50%; and,

[0072] the printing slice layer thickness is 10 to 100 μm.

[0073] In a third aspect, the present application also provides an application of the broadband heat-insulating ceramic wave-absorbing material of the present invention. Specifically, the broadband heat-insulating ceramic wave-absorbing material of the present invention is used in the fields of electromagnetic / infrared compatible stealth, etc. Among them, due to the advantages of low density, wide absorption frequency band, good wave-absorbing performance, good heat insulation, etc. of the broadband heat-insulating ceramic wave-absorbing material of the present invention, the infrared signal can be effectively reduced and an excellent comprehensive stealth effect can be achieved.

[0074] The technical solutions of the present application will be further described below in conjunction with specific embodiments.

[0075] Example 1

[0076] This example provides the preparation of a coaxial ring broadband heat-insulating ceramic wave-absorbing material [SiBOC(60wt%HGM)-1100℃], specifically including:

[0077] S1: Heat a 500 mL Schlenk flask to 100 °C with a hot air gun. After fully removing water vapor, perform the "vacuum pumping - argon gas passing" cyclic operation 3 times to ensure an anhydrous and oxygen-free argon gas environment inside the flask. While continuously passing argon gas into the flask and stirring, add 400 mL of 1,4-dioxane into the flask, and then sequentially add 70.00 g (1.17 mol) of methylboronic acid into the flask. After the methylboronic acid is dissolved evenly, add 51.20 g (0.20 mol) of 3-(methacryloyloxy)propyltrimethoxysilane, 24.94 g (0.1 mol) of diphenyldimethoxysilane, 95.42 g (0.7 mol) of dimethoxymethylvinylsilane, and 2 g (0.02 mol) of trimethylmethoxysilane through a syringe, and continuously stir and react at a temperature of 90 °C for 8 h. The reaction product is placed in a water bath at 50 °C and heated and vacuum rotary evaporated for 3 h to remove 1,4-dioxane and by-products, and a photosensitive polyborosiloxane (UV-PBSO) is prepared.

[0078] S2: Add 5 g (10 wt%) of pentaerythritol tetraacrylate to 50 g of UV-PBSO. After mixing evenly, add 2.2 g (4 wt%) of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) and stir evenly in the dark, and then add 60 wt% of hollow glass microspheres (iM30K, HGM) and mix evenly to obtain a polymer precursor slurry (60 wt%HGM / UV-PBSO).

[0079] S3: Add 60wt% HGM / UV-PBSO to the raw material tank of the DLP 3D printer. The wavelength of the printer light source is 405 nm, and the parameter settings are as follows: the irradiation intensity of the light source is 7 mW / cm 2 , the single-layer exposure time is 2 s, and the moving speed of the squeegee is 50%. Use the slicing software 10dim to slice the 3D modeling printing model, and the slicing thickness is 50 μm. After inputting the generated printer-specific file into the printer, print it into a coaxial ring polymer green body (60wt% HGM / -UV-PBSO).

[0080] S4: Place the 60wt% HGM / -UV-PBSO into a tubular vacuum furnace and pyrolyze it at 1100 °C in an argon atmosphere to obtain the coaxial ring broadband thermal insulation ceramic wave-absorbing material SiBOC (60wt% HGM)-1100 °C.

[0081] Among them, Figure 1 are the physical photos of the coaxial ring polymer green body with 60wt% HGM doping and the corresponding coaxial ring broadband thermal insulation ceramic wave-absorbing material.

[0082] According to Figure 1 It can be seen that the structures of the coaxial ring broadband thermal insulation ceramic wave-absorbing material with 60wt% HGM doping and the coaxial ring polymer green body with 60wt% HGM doping are highly similar, only the volume has shrunk to a certain extent, indicating that the structure has not changed during the pyrolysis ceramization process. Among them, the inner diameter of SiBOC (60wt% HGM)-1100 °C is 3.04 mm, and the outer diameter is 7.00 mm.

[0083] Examples 2-4

[0084] Referring to the preparation process of Example 1, the difference is that the addition amounts of the hollow glass microspheres mentioned in step S2 are respectively replaced with 40wt%, 50wt% and 70wt%, and the coaxial ring broadband thermal insulation ceramic wave-absorbing materials SiBOC (40wt% HGM)-1100 °C, SiBOC (50wt% HGM)-1100 °C and SiBOC (70wt% HGM)-1100 °C are prepared in sequence.

[0085] Examples 5-7

[0086] Referring to the preparation process of Example 1, the difference is that the pyrolysis temperatures mentioned in step S4 are respectively replaced with 1200 °C, 1000 °C and 800 °C, and the coaxial ring broadband thermal insulation ceramic wave-absorbing materials SiBOC (60wt% HGM)-1200 °C, SiBOC (50wt% HGM)-1000 °C and SiBOC (70wt% HGM)-800 °C are prepared in sequence.

[0087] Example 8

[0088] Referring to the preparation process of Example 1, the differences are as follows: while replacing the addition amount of the hollow glass microspheres mentioned in step S2 with 40 wt%, the pyrolysis temperature mentioned in step S4 is replaced with 1000 °C, and the coaxial ring broadband heat-insulating ceramic wave-absorbing material SiBOC(40wt%HGM)-1000℃ is prepared.

[0089] Comparative Example 1

[0090] Referring to the preparation process of Example 1, the differences are as follows: the addition of the hollow glass microspheres mentioned in step S2 is omitted, and the coaxial ring broadband heat-insulating ceramic wave-absorbing material SiBOC(0wt%HGM)-1100℃ is prepared.

[0091] Comparative Example 2

[0092] Referring to the preparation process of Example 1, the differences are as follows: the addition of the hollow glass microspheres mentioned in step S2 is omitted, and the pyrolysis temperature mentioned in step S4 is replaced with 1000 °C, and the coaxial ring broadband heat-insulating ceramic wave-absorbing material SiBOC(0wt% HGM)-1000℃ is prepared.

[0093] To clarify the actual performance of the broadband heat-insulating ceramic wave-absorbing material prepared in the embodiments of the present invention, the present application is described in conjunction with the following test results.

[0094] 1. Dielectric constant

[0095] To verify the influence of the HGM doping amount on the dielectric properties, the present application uses the MS4644A vector network analyzer of Anritsu Corporation of Japan and measures the dielectric parameters of the coaxial ring broadband heat-insulating ceramic wave-absorbing materials SiBOC(40wt%HGM)-1100℃, SiBOC(50wt% HGM)-1100℃, SiBOC(60wt%HGM)-1100℃, and SiBOC(70wt%HGM)-1100℃ prepared in Examples 1 to 4 respectively based on the coaxial method (non-magnetic mode). The results are Figure 2 as shown. Among them, Figure 2 is the dielectric property diagram of the coaxial ring broadband heat-insulating ceramic wave-absorbing material with different HGM doping amounts.

[0096] According to Figure 2 it can be seen that the addition of HGM can effectively reduce the dielectric properties of the composite ceramic, and at the same time, the pyrolysis temperature also has an important influence on the regulation of the dielectric properties of the composite ceramic.

[0097] 2. Impedance matching

[0098] The present application also calculates and fits and analyzes the impedance matching based on Figure 2 the measured dielectric parameters. The results are Figure 3 as shown. Among them, Figure 3Impedance matching diagram of coaxial ring broadband heat-insulating ceramic wave-absorbing materials with different HGM contents.

[0099] When the impedance matching is closer to 1, electromagnetic waves can enter the wave-absorbing material interior to the greatest extent, which is more conducive to reducing electromagnetic wave loss and improving wave-absorbing performance. According to Figure 3 it can be seen that the addition of HGM can effectively adjust the impedance matching and improve the wave-absorbing performance of the composite ceramic.

[0100] 3. Wave-absorbing performance

[0101] To verify the effects of HGM content and pyrolysis temperature on wave-absorbing performance, this application calculated the wave-absorbing performance of the coaxial ring broadband heat-insulating ceramic wave-absorbing materials SiBOC(40wt%HGM)-1100℃, SiBOC(50wt%HGM)-1100℃, SiBOC(60wt%HGM)-1100℃, SiBOC(70wt% HGM)-1100℃, SiBOC(60wt%HGM)-1000℃, SiBOC(60wt%HGM)-1200℃ prepared in Examples 1 to 6 based on the coaxial method within 2 - 18 GHz. The results are Figure 4 as shown. Among them, Figure 4 is the wave-absorbing performance diagram of the coaxial ring broadband heat-insulating ceramic wave-absorbing materials prepared with different HGM contents and different pyrolysis temperatures within 2 - 18 GHz.

[0102] According to Figure 4It can be seen that the minimum reflection loss of SiBOC(40wt%HGM)-1100℃ is -17.6 dB(7.5 mm), and the optimal absorption bandwidth is 3.92 GHz(1.9 mm); the minimum reflection loss of SiBOC(50wt%HGM)-1100℃ is -27.9 dB(5.8 mm), and the optimal absorption bandwidth is 7.50 GHz(2.2 mm); the minimum reflection loss of SiBOC(60wt%HGM)-1100℃ is -43.4 dB(5.7 mm), and the optimal absorption bandwidth is 8.48 GHz(3.2 mm); the minimum reflection loss of SiBOC(70wt%HGM)-1100℃ is -49.4 dB(3.9 mm), and the optimal absorption bandwidth is 7.3 GHz(2.6 mm); the minimum reflection loss of SiBOC(60wt%HGM)-1000℃ is -12.3 dB(5.7 mm), and the optimal absorption bandwidth is 0.8 GHz(4.8 mm); the minimum reflection loss of SiBOC(60wt%HGM)-1200℃ is -54.8 dB(5.7 mm), and the optimal absorption bandwidth is 7.44 GHz(3.1 mm). Therefore, the wave absorption performance of SiBOC(60wt%HGM)-1100℃ is the best at a single thickness, which can reach 8.48 GHz(3.2 mm) within 2 - 18 GHz. Moreover, the addition of HGM and the change of pyrolysis temperature both have a significant impact on the wave absorption performance, which can effectively improve the wave absorption performance.

[0103] 4. Thermal Conductivity

[0104] To verify the influence of the HGM content on the heat insulation performance of the coaxial ring broadband heat insulation ceramic wave absorbing material, the present application also tested the thermal conductivities of SiBOC(0wt%HGM)-1100℃, SiBOC(40wt%HGM)-1100℃ and SiBOC(60wt%HGM)-1100℃ respectively, and the results are Figure 5 as shown. Among them, Figure 5 is the thermal conductivity diagram of SiBOC(0wt% HGM)-1100℃, SiBOC(40wt%HGM)-1100℃ and SiBOC(60wt%HGM)-1100℃.

[0105] According to Figure 5 it can be known that the incorporation of HGM has an impact on the thermal conductivity of the coaxial ring broadband heat insulation ceramic wave absorbing material, and the thermal conductivity of the broadband heat insulation ceramic wave absorbing material decreases with the increase of the hollow glass microsphere content.

[0106] 5. Infrared Stealth Performance

[0107] To verify the heat insulation performance of the coaxial ring broadband heat insulation ceramic absorbing material, this application also heated SiBOC (60wt% HGM)-1100°C (thickness 10.5 mm) on a heating table with a heat source temperature of 420°C, and measured the change of its central temperature over time through an infrared spectrometer. The results are as follows Figure 6 as shown. Among them, Figure 6 is the high-temperature infrared thermal imaging diagram of SiBOC (60wt% HGM)-1100°C.

[0108] According to Figure 6 it can be seen that the coaxial ring broadband heat insulation ceramic absorbing material with a thickness of 10.5 mm reaches the equilibrium temperature within 180 s, and can finally isolate a high temperature of 193.8°C, with a temperature isolation rate of 46.1%.

[0109] The above test results show that the coaxial ring broadband heat insulation ceramic absorbing material prepared by pyrolytic ceramization transformation after the polymer precursor slurry provided in this application is formed into a coaxial ring polymer green body by photocuring 3D printing has small reflection loss, a wide absorption band and good heat insulation performance. Especially when the content of hollow glass microspheres is 60wt% and the pyrolysis temperature is 1100°C, the minimum reflection loss of the prepared SiBOC (60wt% HGM)-1100°C reaches -43.4 dB (5.7 mm), and the best absorption bandwidth reaches 8.48 GHz (3.2 mm), with the best comprehensive wave absorption performance, and also has good heat insulation performance, and the thermal conductivity drops to 0.208 W / mK.

[0110] Example 9

[0111] Referring to the preparation process of Example 1, the difference is that in step S3, 60wt% HGM / UV-PBSO is printed into a Schwarz P structured polymer green body, and finally a Schwarz P structured broadband heat insulation ceramic absorbing material is prepared.

[0112] Comparative Example 3

[0113] Referring to the preparation process of Example 9, the difference is that the addition of hollow glass microspheres mentioned in step S2 is omitted to prepare a Schwarz P structured broadband heat insulation ceramic absorbing material.

[0114] Among them, Figure 7 are the physical photos of the Schwarz P structured polymer green body and the corresponding Schwarz P structured broadband heat insulation ceramic absorbing material with a 60wt% HGM content.

[0115] According to Figure 7It can be seen that the structures of the Schwarz P-structured broadband heat-insulating ceramic wave-absorbing material and the Schwarz P-structured polymer green body are highly similar, except that there is a certain reduction in volume, indicating that the pyrolytic ceramization process does not cause changes in complex structures.

[0116] To further illustrate the influence of the structure on the wave-absorbing performance, in this application, a waveguide method vector network analyzer is used to measure the dielectric properties of the Schwarz P-structured broadband heat-insulating ceramic wave-absorbing material within 2 - 18 GHz. Among them, according to the different test frequency bands, waveguide sample pieces of different sizes are prepared for the composite ceramic samples, as shown in the following table:

[0117]

[0118] Among them, Figure 8 shows the wave-absorbing performance diagrams of the Schwarz P-structured broadband heat-insulating ceramic wave-absorbing material with different HGM contents within 2 - 18 GHz.

[0119] According to Figure 8 it can be known that the effective wave-absorbing bandwidth of the Schwarz P-structured broadband heat-insulating ceramic wave-absorbing material with 0 wt% HGM content is 5.68 GHz at a thickness of 2.4 mm; the effective wave-absorbing bandwidth of the Schwarz P-structured broadband heat-insulating ceramic wave-absorbing material with 60 wt% HGM content is 8.56 GHz at a thickness of 2.5 mm, which also indicates that the addition of HGM can effectively improve the wave-absorbing performance of the complex-structured ceramic materials prepared by 3D printing. At the same time, by comparing Figure 8 with Figure 4 it can be known that the Schwarz P structure can further broaden the optimal wave-absorbing bandwidth and improve the wave-absorbing performance.

[0120] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other, and the key points of each embodiment are the differences from other embodiments.

[0121] The above embodiments are only used to illustrate the technical solutions of this application, rather than limiting this application; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of this application.

Claims

1. A broadband heat-insulating ceramic wave-absorbing material, characterized in that, It includes a composite ceramic formed by photocuring a polymer green body through the following polymer precursor slurry and subjecting the polymer green body to pyrolytic ceramization; Among them, the polymer precursor slurry includes: (1) Photosensitive polyborosiloxane; (2) Hollow glass microspheres; (3) Acrylate crosslinking agent; (4) Initiator.

2. The broadband heat-insulating ceramic wave-absorbing material according to claim 1, wherein The hollow glass microspheres are selected as borosilicate hollow glass microspheres, with a particle size of 5 - 40 μm and a wall thickness of 0.5 - 3 μm.

3. The broadband heat-insulating ceramic wave-absorbing material according to claim 2, characterized in that, The content of the hollow glass microspheres is 20 - 80 wt% of the sum of the masses of the photosensitive polyborosiloxane, acrylate crosslinking agent, and photoinitiator.

4. The broadband heat-insulating ceramic wave-absorbing material according to claim 1, characterized in that, The acrylate crosslinking agent is any one of pentaerythritol tetraacrylate, 1,6 - hexanediol diacrylate, and trimethylolpropane triacrylate, and its content is 5 - 30 wt% of the mass of the photosensitive polyborosiloxane.

5. The broadband heat-insulating ceramic wave-absorbing material according to claim 1, wherein The initiator is selected as 2,4,6 - trimethylbenzoyl - diphenylphosphine oxide, and its content is 1 - 6 wt% of the sum of the masses of the photosensitive polyborosiloxane and acrylate crosslinking agent.

6. A preparation method of the broadband heat-insulating ceramic wave-absorbing material according to any one of claims 1 to 5, characterized in that, It includes the following steps: Prepare photosensitive polyborosiloxane; Add an acrylate crosslinking agent, an initiator, and hollow glass microspheres to the photosensitive polyborosiloxane and mix evenly to obtain a polymer precursor slurry; Photocure the polymer precursor slurry by 3D printing to form a polymer green body, and perform pyrolytic ceramization treatment on the polymer green body to obtain the broadband heat - insulating ceramic absorbing material.

7. The preparation method according to claim 6, characterized in that, The preparation of the photosensitive polyborosiloxane includes: Provide a precursor solution containing methylboronic acid, 3 - (methacryloyloxy)propyltrimethoxysilane, diphenyldimethoxysilane, dimethoxymethylvinylsilane, and trimethylmethoxysilane; Place the precursor solution at a temperature of 60 - 120 °C and stir - react for 3 - 10 h, and perform vacuum rotary evaporation drying on the reaction product to obtain photosensitive polyborosiloxane.

8. The preparation method according to claim 7, characterized in that, The molar ratio of the methylboronic acid, 3 - (methacryloyloxy)propyltrimethoxysilane, diphenyldimethoxysilane, dimethoxymethylvinylsilane, and trimethylmethoxysilane is (1 - 1.5):(0.1 - 0.4):(0.05 - 0.4):(0.4 - 1):(0.01 - 0.05).

9. The preparation method according to claim 6, characterized in that, The parameter settings of the photocuring 3D printing include: Light source irradiation intensity: 5 - 15 mW / cm 2 , single-layer exposure duration: 2 - 15 s; The moving speed of the doctor blade is 50%; and, The layer thickness of the printed slice is 10 - 100 μm.

10. The application of the broadband heat - insulating ceramic absorbing material according to any one of claims 1 - 5 in the field of electromagnetic and infrared compatible stealth.

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