A broadband thermal insulation ceramic absorbing material, its preparation method and infrared stealth application

Abstract

The present application discloses a broadband thermal insulation ceramic absorbing material, its preparation method and infrared stealth application, which belongs to the field of functional material technology. The absorbing material of the present application comprises a composite ceramic formed by photocuring 3D printing a polymer embryo through a polymer precursor slurry, and subjecting the polymer embryo to pyrolysis and ceramicization, wherein the polymer precursor slurry comprises photosensitive polyborosiloxane, hollow glass microspheres, acrylate crosslinking agents and initiators. The present application effectively achieves the controllable molding of structural and functional integrated ceramic absorbing materials by doping hollow glass microspheres into the polymer precursor slurry containing photosensitive polysiloxane and combining 3D printing coupled pyrolysis and ceramic molding technology. The preparation is simple, the cost is low and the molding composite ceramic structure can be precisely controlled. At the same time, the prepared absorbing material has the advantages of multiple reflection loss mechanisms, adjustable impedance matching, widened absorbing frequency band and good thermal insulation performance, and has good electromagnetic and infrared compatible stealth performance.

Description

Technical Field

[0001] The present application belongs to the technical field of absorbing materials, and in particular relates to a broadband thermal insulation ceramic absorbing material, a preparation method thereof, and infrared stealth applications. Background Art

[0002] Ceramic absorbers offer advantages such as high temperature resistance, high strength, low creep, and corrosion resistance, making them highly advantageous for infrared stealth. However, the molding temperatures of traditional ceramic absorbers are generally high (>1600°C), hindering their commercialization prospects. Consequently, the design of high-performance ceramic absorbers that are easy to mold has attracted considerable attention.

[0003] At present, relevant reports have disclosed the technical strategy of polymer conversion into ceramics, that is, after designing and synthesizing a high-molecular polymer with a specific structure, it is pyrolyzed at 800~1400℃ to form ceramic absorbing materials. This has the advantages of low pyrolysis temperature and clear composition, and has good prospects for use in microdevices, stealth coatings and other fields.

[0004] However, the existing polymer-to-ceramic technology still has shortcomings. For example, the volume shrinkage during the ceramic transformation can easily cause cracks or structural collapse, resulting in great technical difficulties in preparing ceramic absorbing materials with integrated molding structure and function, which limits large-scale production. Summary of the Invention

[0005] The present application discloses a broadband thermal insulation ceramic absorbing material, a preparation method thereof, and infrared stealth applications. By setting a polymer precursor slurry with a specific composition and combining 3D printing coupled pyrolysis ceramic molding technology, the controllable preparation of a structurally and functionally integrated ceramic absorbing material is effectively achieved.

[0006] In order to achieve the above objectives, the technical solutions adopted in this application are:

[0007] In a first aspect, the present application provides a broadband thermal insulation ceramic absorbing material, which comprises a composite ceramic formed by photocuring 3D printing a polymer blank using the following polymer precursor slurry, and pyrolyzing and ceramicizing the polymer blank;

[0008] Wherein, the polymer precursor slurry comprises:

[0009] (1) Photosensitive polyborosiloxane;

[0010] (2) Hollow glass microspheres;

[0011] (3) Acrylate crosslinking agent;

[0012] (4) Initiator.

[0013] According to the broadband thermal insulation ceramic absorbing material disclosed herein, the hollow glass microspheres are selected as borosilicate hollow glass microspheres, with a particle size of 5 to 40 μm and a wall thickness of 0.5 to 3 μm.

[0014] According to the broadband thermal insulation ceramic absorbing material disclosed herein, the content of the hollow glass microspheres is 20-80 wt % of the sum of the mass of the photosensitive polyborosiloxane, the acrylate crosslinking agent and the photoinitiator.

[0015] According to the broadband thermal insulation ceramic absorbing material disclosed herein, the acrylate crosslinking agent is any one of pentaerythritol tetraacrylate, 1,6-hexanediol diacrylate, and trimethylolpropane triacrylate, and its content is 5-30wt% of the mass of the photosensitive polyborosiloxane.

[0016] According to the broadband thermal insulation ceramic absorbing material disclosed herein, the initiator is selected from 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and its content is 1-6 wt % of the sum of the mass of the photosensitive polyborosiloxane and the acrylate crosslinking agent.

[0017] A second aspect of the present application further provides a method for preparing the broadband thermal insulation ceramic absorbing material of the present invention, which comprises the following steps:

[0018] Preparation of photosensitive polyborosiloxane;

[0019] Adding an acrylate crosslinking agent, an initiator, and hollow glass microspheres to the photosensitive polyborosiloxane and mixing them uniformly to prepare a polymer precursor slurry;

[0020] The polymer precursor slurry is subjected to light-curing 3D printing to form a polymer embryo, and the polymer embryo is subjected to pyrolysis and ceramic treatment to obtain the broadband thermal insulation ceramic absorbing material.

[0021] According to the preparation method disclosed herein, the preparation of photosensitive polyborosiloxane comprises:

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

[0023] The precursor solution is placed at a temperature of 60-120° C. and stirred for reaction for 3-10 hours, and the reaction product is vacuum-dried by rotary evaporation to obtain photosensitive polyborosiloxane.

[0024] According to the preparation method disclosed herein, the molar ratio of methylboric 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).

[0025] According to the preparation method disclosed herein, the parameter settings for the light-curing 3D printing include:

[0026] Light source irradiation intensity 5~15mW / cm 2 , single layer exposure time is 2~15s;

[0027] Scraper movement speed 50%; and,

[0028] The printed slice layer thickness is 10~100μm.

[0029] The third aspect of the present application also provides the application of the broadband thermal insulation 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 this application include at least:

[0031] The present invention effectively achieves the controllable preparation of structural and functional integrated ceramic absorbing materials by setting a polymer precursor slurry containing the above-mentioned components and combining it with 3D printing coupled pyrolysis ceramic conversion molding technology. It is simple to operate, low-cost and can accurately control the molded composite ceramic structure. Specifically, through the combined design of the components contained in the polymer precursor slurry, and the structural and functional integration of the complex and precise structure control of 3D printing and the pyrolysis ceramic coupling molding strategy, it can not only give the molded composite ceramics multiple reflection loss mechanisms and good impedance matching, so that the molded composite ceramics have excellent absorbing performance, but also can broaden the absorption bandwidth of the molded composite ceramics and reduce the density, so that the composite ceramic absorbing material has the characteristics of low density and wide absorption bandwidth. At the same time, it can also enhance the thermal insulation performance of the molded composite ceramics, thereby reducing infrared signals and improving comprehensive stealth performance. It has broad prospects for use in the field of electromagnetic / infrared compatible stealth. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To more clearly illustrate the technical solutions of the embodiments of this application, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some of the embodiments described in this application. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0033] Figure 1Photos of the coaxial ring polymer embryo with a 60wt% HGM content and the corresponding coaxial ring broadband thermal insulation ceramic absorbing material provided in this application;

[0034] Figure 2 The dielectric properties of the coaxial ring broadband thermal insulation ceramic absorbing material with different HGM doping amounts provided in this application;

[0035] Figure 3 Impedance matching diagram of the coaxial ring broadband thermal insulation ceramic absorbing material with different HGM doping amounts provided in this application;

[0036] Figure 4 This is a graph showing the absorption performance of the coaxial ring broadband thermal insulation ceramic absorbing material prepared at different HGM dosages and different pyrolysis temperatures provided in this application within the range of 2-18 GHz;

[0037] Figure 5 Thermal conductivity diagram of the coaxial ring broadband thermal insulation ceramic absorbing material with different HGM dosages provided in this application;

[0038] Figure 6 This is a high-temperature infrared thermal imaging image of the coaxial ring broadband thermal insulation ceramic absorbing material with a 60wt% HGM content provided in this application;

[0039] Figure 7 Photos of the Schwarz P structured polymer blank with 60 wt% HGM content and the corresponding Schwarz P structured broadband thermal insulation ceramic absorbing material provided in this application;

[0040] Figure 8 This is a graph of the absorption performance of the Schwarz P structured broadband thermal insulation ceramic absorbing material with different HGM content provided in this application within the range of 2~18GHz. DETAILED DESCRIPTION

[0041] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are 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 can represent: A exists alone, B exists alone, and A and B exist at the same time. A and B can be singular or plural.

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

[0044] In the following description of the present disclosure, the order of serial numbers does not mean the order of execution. Some or all steps can be executed in parallel or sequentially. The execution order of each process should be determined based on its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0045] In the following description of the present disclosure, numerical ranges should be understood to also specifically disclose every intervening value between the upper and lower limits of the range. Each smaller range between any stated value or stated range and any other stated value or intervening value in the stated range is also included in this application. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

[0046] Unless otherwise indicated, the technical / scientific terms used in this disclosure have the same meanings as those commonly understood by those skilled in the art. Although this application describes only preferred methods and materials, any methods and materials similar or equivalent to those described in this disclosure may also be used in the practice or testing of this disclosure. All documents mentioned in this disclosure are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this disclosure shall prevail.

[0047] In a first aspect, an embodiment of the present invention provides a broadband thermal insulation ceramic absorbing material, the broadband thermal insulation ceramic absorbing material comprising a composite ceramic formed by photocuring 3D printing a polymer blank using the following polymer precursor slurry, and pyrolyzing and ceramicizing the polymer blank;

[0048] Wherein, the polymer precursor slurry comprises:

[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 embryo can be various simple or complex structures, such as a simple coaxial ring structure or a complex Schwarz P structure; the pyrolysis ceramicization refers to the process of pyrolyzing the polymer embryo to generate ceramics.

[0054] In combination with the above, the present invention effectively achieves the controllable preparation of structural and functional integrated ceramic absorbing materials by setting a polymer precursor slurry containing the above ingredients and combining it with 3D printing coupled pyrolysis ceramic conversion molding technology. It is simple to operate, low cost and can accurately control the molding of composite ceramic structures, which is convenient for large-scale industrial production. Specifically, by setting a combination of effective ingredients contained in the polymer precursor slurry and 3D printing complex structure coupled pyrolysis ceramic molding technology, a structural and functional integrated composite ceramic absorbing material is accurately constructed. First, it can give the molded composite ceramic multiple reflection loss mechanisms and good impedance matching, effectively improving the absorbing ability of the composite ceramic absorbing material; second, it can broaden the absorption bandwidth of the molded composite ceramic and reduce the density, so that the composite ceramic wave absorbing material has the characteristics of low density and wide absorption bandwidth; third, it can also enhance the thermal insulation performance of the molded composite ceramic, reduce infrared signals and improve comprehensive stealth performance, and has broad prospects for use in the field of electromagnetic / infrared compatible stealth.

[0055] In the specific example of the present disclosure, the hollow glass microspheres are preferably commercially available borosilicate hollow glass microspheres, more preferably borosilicate hollow glass microspheres with a particle size of 5~40um and a wall thickness of 0.5~3μm, for example, 3M™ hollow glass microspheres iM30K are used in the embodiment of the present invention.

[0056] In the specific example of the present disclosure, the content of the hollow glass microspheres is preferably 20~80wt% of the sum of the mass of the photosensitive polyborosiloxane, acrylate crosslinker and photoinitiator, and can be preferably 40~70wt%, and more preferably 60wt%, so that the formed composite ceramic has minimal reflection loss, optimal absorption bandwidth and lowest thermal conductivity, so as to be 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 from 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and its content is 1-6 wt % of the sum of the mass of the photosensitive polyborosiloxane and the acrylate crosslinker, and may be preferably 4 wt %.

[0059] In a second aspect, the present application also discloses a method for preparing the broadband thermal insulation ceramic absorbing material of the present invention, the steps of which include:

[0060] Preparation of photosensitive polyborosiloxane;

[0061] Adding an acrylate crosslinking agent, an initiator, and hollow glass microspheres to the photosensitive polyborosiloxane and mixing them uniformly to prepare a polymer precursor slurry;

[0062] The polymer precursor slurry is subjected to light-curing 3D printing to form a polymer embryo, and the polymer embryo is subjected to pyrolysis and ceramic treatment to obtain the broadband thermal insulation ceramic absorbing material.

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

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

[0065] The precursor solution is placed at a temperature of 60-120° C. and stirred for reaction for 3-10 hours, and the reaction product is vacuum-dried by rotary evaporation to obtain photosensitive polyborosiloxane.

[0066] It should be noted that the present application does not specifically limit the specific parameters for the stirring reaction of the above-mentioned precursor solution, and can be any value within the range, such as 60℃ / 10h, 70℃ / 9h, 90℃ / 8h, 100℃ / 6h, 120℃ / 3h, etc.

[0067] In the specific examples of the present disclosure, the molar ratio of methylboric 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), for example, 1.17: 0.2: 0.1: 0.7: 0.02, etc.

[0068] It is understood by those skilled in the art that the precursor solution in the preferred example of the present disclosure should be prepared in an inert atmosphere without water or oxygen. The present application does not specifically limit 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 light-curing 3D printing are preferably:

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

[0071] Scraper movement speed 50%; and,

[0072] The printed slice layer thickness is 10~100μm.

[0073] Thirdly, this application also provides applications of the broadband thermal-insulating ceramic absorbing material described herein. Specifically, the broadband thermal-insulating ceramic absorbing material described herein is used in fields such as electromagnetic / infrared compatible stealth. Due to its low density, wide absorption bandwidth, excellent absorbing performance, and superior thermal insulation, the broadband thermal-insulating ceramic absorbing material described herein can effectively reduce infrared signals and achieve excellent overall stealth effects.

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

[0075] Example 1

[0076] This example provides a preparation method for a coaxial ring broadband thermal insulation ceramic absorbing material [SiBOC (60wt% HGM)-1100°C], which specifically includes:

[0077] S1: Heat a 500 mL Schlenk flask to 100°C using a heat gun. After sufficient removal of moisture, perform a "vacuum-and-argon" cycle three times to ensure an argon-free, water-free, and oxygen-free environment in the flask. While continuously passing argon into the bottle and stirring, 400 mL of 1,4-dioxane was added to the bottle, and 70.00 g (1.17 mol) of methylboric acid was added to the bottle in sequence. After the methylboric acid was evenly dissolved, 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 were added via a syringe, and the reaction was stirred at 90 ° C for 8 h. The reaction product was 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 to obtain photosensitive polyborosiloxane (UV-PBSO).

[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. 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 into the raw material tank of the DLP 3D printer. The wavelength of the printer light source is 405nm. The parameters are set as follows: the light source irradiation intensity is 7mW / cm 2 The single-layer exposure time was 2 seconds, and the scraper speed was 50%. The 3D printed model was sliced ​​using 10dim slicing software with a slice thickness of 50 μm. The generated printer-specific file was input into the printer and printed into a coaxial ring polymer embryo (60wt% HGM / -UV-PBSO).

[0080] S4: 60wt% HGM / -UV-PBSO was placed in a tubular vacuum furnace and pyrolyzed at 1100°C in an argon atmosphere to obtain a coaxial ring broadband thermal insulation ceramic absorber SiBOC (60wt% HGM)-1100°C.

[0081] in, Figure 1 These are actual photos of the coaxial ring polymer embryo with 60wt% HGM doping and the corresponding coaxial ring broadband thermal insulation ceramic absorbing material.

[0082] according to Figure 1 It can be seen that the structures of the coaxial ring broadband thermal insulation ceramic absorber with a 60wt% HGM content and the coaxial ring polymer embryo with a 60wt% HGM content remain highly similar, with only a certain reduction in volume, indicating that the pyrolysis ceramicization process did not cause any structural changes. Among them, the inner diameter of SiBOC (60wt% HGM) at -1100℃ is 3.04mm, and the outer diameter is 7.00mm.

[0083] Examples 2 to 4

[0084] The preparation process was similar to that of Example 1, except that the amounts of hollow glass microspheres added in step S2 were replaced with 40 wt %, 50 wt %, and 70 wt %, respectively, to prepare coaxial ring broadband thermal insulation ceramic absorbing materials SiBOC (40 wt % HGM)-1100°C, SiBOC (50 wt % HGM)-1100°C, and SiBOC (70 wt % HGM)-1100°C, respectively.

[0085] Examples 5 to 7

[0086] The preparation process was similar to that of Example 1, except that the pyrolysis temperatures in step S4 were replaced with 1200°C, 1000°C, and 800°C, respectively, to prepare coaxial ring broadband thermal insulation ceramic absorbing materials SiBOC (60wt% HGM)-1200°C, SiBOC (50wt% HGM)-1000°C, and SiBOC (70wt% HGM)-800°C, respectively.

[0087] Example 8

[0088] The preparation process is similar to that of Example 1, except that the amount of hollow glass microspheres added in step S2 is replaced with 40 wt %, and the pyrolysis temperature in step S4 is replaced with 1000° C. to obtain a coaxial ring broadband thermal insulation ceramic absorbing material SiBOC (40 wt % HGM)-1000° C.

[0089] Comparative Example 1

[0090] The preparation process was similar to that of Example 1, except that the addition of the hollow glass microspheres in step S2 was omitted, and a coaxial ring broadband thermal insulation ceramic absorbing material SiBOC (0 wt % HGM)-1100°C was obtained.

[0091] Comparative Example 2

[0092] The preparation process is similar to that of Example 1, except that the addition of hollow glass microspheres described in step S2 is omitted, and the thermal cracking temperature described in step S4 is replaced with 1000°C to obtain a coaxial ring broadband thermal insulation ceramic absorbing material SiBOC (0wt% HGM)-1000°C.

[0093] In order to illustrate the actual performance of the broadband thermal insulation ceramic absorbing material prepared in the embodiment of the present invention, this application is described in conjunction with the following test results.

[0094] 1. Dielectric constant

[0095] In order to verify the effect of HGM content on dielectric properties, the present application used the MS4644A vector network analyzer of Anristu Company of Japan and measured the dielectric parameters of the coaxial ring broadband thermal insulation ceramic 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 based on the coaxial method (non-magnetic mode). The results are as follows: Figure 2 As shown. Among them, Figure 2 The dielectric properties of coaxial ring broadband thermal insulation ceramic absorbing materials with different HGM doping amounts are shown in the figure.

[0096] according to Figure 2 It can be seen that the addition of HGM can effectively reduce the dielectric properties of composite ceramics, and the pyrolysis temperature also has an important influence on the regulation of the dielectric properties of composite ceramics.

[0097] 2. Impedance matching

[0098] This application is also based on Figure 2 The measured dielectric parameters were calculated and fitted to analyze the impedance matching, and the results were as follows: Figure 3 As shown. Among them, Figure 3Impedance matching diagram of coaxial ring broadband thermal insulation ceramic absorbing material with different HGM doping amounts.

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

[0100] 3. Wave absorbing performance

[0101] In order to verify the influence of HGM content and pyrolysis temperature on the absorption performance, the present application tests and calculates the absorption performance of the coaxial ring broadband thermal insulation ceramic absorbing materials SiBOC (40wt% HGM)-1100℃, SiBOC (50wt% HGM)-1100℃, SiBOC (60wt% HGM)-1100℃, SiBOC (70wt% HGM)-1100℃, SiBOC (60wt% HGM)-1000℃, and SiBOC (60wt% HGM)-1200℃ prepared in Examples 1 to 6 in the range of 2 to 18 GHz based on the coaxial method. The results are as follows: Figure 4 As shown. Among them, Figure 4 The diagram shows the absorbing performance of the coaxial ring broadband thermal insulation ceramic absorbing material prepared at different HGM dosages and different pyrolysis temperatures within 2~18GHz.

[0102] according to Figure 4It can be seen that the minimum reflection loss of SiBOC (40wt% HGM) at -1100℃ is -17.6dB (7.5mm), and the optimal absorption bandwidth is 3.92GHz (1.9mm); the minimum reflection loss of SiBOC (50wt% HGM) at -1100℃ is -27.9dB (5.8mm), and the optimal absorption bandwidth is 7.50GHz (2.2mm); the minimum reflection loss of SiBOC (60wt% HGM) at -1100℃ is -43.4dB (5.7mm), and the optimal absorption bandwidth is 8.48GHz (3.2mm). The minimum reflection loss of SiBOC (70wt% HGM) at -1100°C was −49.4dB (3.9mm), with an optimal absorption bandwidth of 7.3GHz (2.6mm). The minimum reflection loss of SiBOC (60wt% HGM) at -1000°C was −12.3dB (5.7mm), with an optimal absorption bandwidth of 0.8GHz (4.8mm). The minimum reflection loss of SiBOC (60wt% HGM) at -1200°C was −54.8dB (5.7mm), with an optimal absorption bandwidth of 7.44GHz (3.1mm). Therefore, SiBOC (60wt% HGM) at -1100°C exhibits optimal absorption performance, reaching 8.48GHz (3.2mm) within the 2-18 GHz range. The addition of HGM and changes in the thermal decomposition temperature both significantly affect the absorption performance, effectively improving it.

[0103] 4. Thermal conductivity

[0104] In order to verify the effect of HGM content on the thermal insulation performance of the coaxial ring broadband thermal insulation ceramic absorber, the thermal conductivity of SiBOC (0wt% HGM)-1100℃, SiBOC (40wt% HGM)-1100℃ and SiBOC (60wt% HGM)-1100℃ were tested respectively. The results are as follows: Figure 5 As shown. Among them, Figure 5 Thermal conductivity diagrams of SiBOC (0wt% HGM)-1100℃, SiBOC (40wt% HGM)-1100℃ and SiBOC (60wt% HGM)-1100℃.

[0105] according to Figure 5 It can be seen that the addition of HGM affects the thermal conductivity of the coaxial ring broadband thermal insulation ceramic absorber, and the thermal conductivity of the broadband thermal insulation ceramic absorber decreases with the increase of the hollow glass microsphere content.

[0106] 5. Infrared stealth performance

[0107] In order to verify the thermal insulation performance of the coaxial ring broadband thermal insulation ceramic absorber, the present application also heated SiBOC (60wt% HGM) -1100℃ (thickness 10.5mm) on a heating table with a heat source temperature of 420℃, and measured the change of its center temperature over time using an infrared spectrometer. The results were as follows: Figure 6 As shown. Among them, Figure 6 This is the high-temperature infrared thermal imaging image of SiBOC (60wt% HGM) at -1100℃.

[0108] according to Figure 6 It can be seen that the coaxial ring broadband thermal insulation ceramic absorbing material with a thickness of 10.5 mm reaches the equilibrium temperature within 180 seconds and can eventually isolate the 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 thermal insulation ceramic absorber material, formed by photocuring 3D printing a polymer precursor slurry and then pyrolyzing and ceramicizing it, exhibits low reflection loss, a wide absorption band, and excellent thermal insulation performance. In particular, when the hollow glass microsphere content is 60wt% and the pyrolysis temperature is 1100°C, the prepared SiBOC (60wt% HGM) achieves a minimum reflection loss of -43.4dB (5.7mm) at -1100°C and an optimal absorption bandwidth of 8.48GHz (3.2mm), achieving the best overall absorption performance. It also has good thermal insulation properties, with a thermal conductivity reduced to 0.208W / mK.

[0110] Example 9

[0111] The preparation process is similar to that of Example 1, except that in step S3, 60 wt % HGM / UV-PBSO is printed into a Schwarz P structured polymer blank, and finally a Schwarz P structured broadband thermal insulation ceramic absorbing material is prepared.

[0112] Comparative Example 3

[0113] The preparation process is similar to that of Example 9, except that the addition of the hollow glass microspheres in step S2 is omitted to obtain a Schwarz P structured broadband thermal insulation ceramic absorbing material.

[0114] in, Figure 7 These are actual photos of the Schwarz P structured polymer embryo with 60wt% HGM doping and the corresponding Schwarz P structured broadband thermal insulation ceramic absorbing material.

[0115] according to Figure 7It can be seen that the structures of the Schwarz P structured broadband thermal insulation ceramic absorber and the Schwarz P structured polymer embryo remain highly similar, with only a certain reduction in volume, indicating that the pyrolysis ceramicization process did not cause any changes in the complex structure.

[0116] To further illustrate the impact of structure on absorbing performance, this application uses a waveguide method vector network analyzer to measure the dielectric properties of Schwarz P structure broadband thermal insulation ceramic absorbing materials within the range of 2-18 GHz. Waveguide samples of different sizes are prepared from the composite ceramic sample according to the different test bands, as shown in the following table:

[0117]

[0118] in, Figure 8 The graph shows the absorption performance of Schwarz P structured broadband thermal insulation ceramic absorber with different HGM content in the range of 2~18GHz.

[0119] according to Figure 8 It can be seen that the effective absorption bandwidth of Schwarz P structured broadband thermal insulation ceramic absorbing material with 0wt% HGM content at 2.4mm thickness is 5.68GHz; the effective absorption bandwidth of Schwarz P structured broadband thermal insulation ceramic absorbing material with 60wt% HGM content at 2.5mm thickness is 8.56GHz, which also shows that the addition of HGM can effectively improve the absorption performance of complex structure ceramic materials prepared by 3D printing. Figure 8 and Figure 4 By comparison, the Schwarz P structure can further broaden the optimal absorption bandwidth and improve the absorption 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 referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0121] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A broadband thermal insulation ceramic absorbing material, characterized in that: The method comprises forming a polymer embryo by photocuring 3D printing of the following polymer precursor slurry, and pyrolyzing and ceramicizing the polymer embryo to generate a composite ceramic; Wherein, the polymer precursor slurry comprises: (1) Photosensitive polyborosiloxane; (2) hollow glass microspheres, wherein the hollow glass microspheres are borosilicate hollow glass microspheres; (3) Acrylate crosslinking agent; (4) photoinitiator; The content of the hollow glass microspheres is 40-70 wt % of the total mass of the photosensitive polyborosiloxane, the acrylate crosslinking agent and the photoinitiator; The preparation of the photosensitive polyborosiloxane comprises: Providing a precursor solution containing methylboric acid, 3-(methacryloyloxy)propyltrimethoxysilane, diphenyldimethoxysilane, dimethoxymethylvinylsilane, and trimethylmethoxysilane; The precursor solution is placed at a temperature of 60-120° C. and stirred for reaction for 3-10 hours, and the reaction product is vacuum-dried by rotary evaporation to obtain photosensitive polyborosiloxane.

2. The broadband thermal insulation ceramic absorbing material according to claim 1, characterized in that: The hollow glass microspheres have a particle size of 5 to 40 μm and a wall thickness of 0.5 to 3 μm.

3. The broadband thermal insulation ceramic 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.

4. The broadband thermal insulation ceramic absorbing material according to claim 1, characterized in that: The photoinitiator is selected from 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and its content is 1-6 wt % of the total mass of the photosensitive polyborosiloxane and the acrylate crosslinking agent.

5. The broadband thermal insulation ceramic absorbing material according to claim 1, characterized in that: The molar ratio of methylboric 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).

6. A method for preparing the broadband thermal insulation ceramic absorbing material according to any one of claims 1 to 5, characterized in that: The following steps are included: Preparation of photosensitive polyborosiloxane; Adding an acrylate crosslinking agent, a photoinitiator, and hollow glass microspheres to the photosensitive polyborosiloxane and mixing them uniformly to prepare a polymer precursor slurry; The polymer precursor slurry is subjected to light-curing 3D printing to form a polymer embryo, and the polymer embryo is subjected to pyrolysis and ceramic treatment to obtain the broadband thermal insulation ceramic absorbing material.

7. The preparation method according to claim 6, characterized in that: The parameter settings of the light-curing 3D printing include: Light source irradiation intensity 5~15mW / cm 2 , single layer exposure time is 2~15s; Scraper movement speed 50%; Also, the printed slice layer thickness is 10~100μm.

8. Application of the broadband thermal insulation ceramic absorbing material according to any one of claims 1 to 5 in the field of electromagnetic and infrared compatible stealth.

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