Application of boron nitride aerogel in laser protection, laser protection material and laser protection method

Abstract

The application discloses application of boron nitride aerogel in laser protection, a laser protection material and a laser protection method. The laser protection material has a three-dimensional porous network structure assembled by boron nitride nano building blocks, and the three-dimensional porous network structure comprises micropores with a pore diameter of less than 2 nm, mesopores with a pore diameter of 2-50 nm and macropores with a pore diameter of 50 nm-100 microns. The laser protection material can effectively reflect laser and manage local high-temperature field and thermal stress in the process of laser irradiation. The laser protection material can withstand continuous laser irradiation and maintain itself intact. The protection power density range of the laser protection material is 1.0-9*10 4 W / cm 2 . Meanwhile, the preparation process of the laser protection material is simple, the preparation period is short, the reaction condition is mild, and the laser protection material has great application value in the field of laser protection.

Description

Technical Field

[0001] This invention relates to a laser protection material, particularly to a novel application of boron nitride aerogel in laser protection, as well as a laser protection material and its preparation method and laser protection method, belonging to the field of laser protection technology. Background Technology

[0002] Laser light is the energy released as photons when electrons in atoms absorb energy and transition from a low energy level to a high energy level, and then fall back down. The emitted photons have similar energies and highly consistent optical properties. Because of this, lasers, with their excellent monochromaticity, collimation, resistance to interference, and high brightness, are now widely used in industry, commerce, scientific research, and medicine.

[0003] With the continuous advancement and expansion of laser science and technology, the hazards of lasers are becoming increasingly prominent, and the research on laser protection materials is receiving more and more attention. However, compared with the rapid development of laser technology, the development of laser protection technology is still in a particularly slow state, and the gap between laser technology and laser protection technology is widening. Therefore, the research on laser protection materials has become an urgent need in all aspects of industrial production and scientific and technological research.

[0004] Laser damage to materials primarily originates from thermal ablation and thermal stress. Therefore, laser protection materials face the following requirements: firstly, they should have the highest possible surface reflectivity to reduce heat absorption and temperature rise; secondly, they should possess high heat sink capacity and low thermal conductivity to increase the protection threshold; and thirdly, in specific situations, they need to withstand ultraviolet and X-rays generated by ionization. Currently, numerous scholars have conducted research on laser protection materials, and their findings can be broadly categorized as follows:

[0005] 1) Ablation-type protection: Utilizing the endothermic reaction of high ablation heat enthalpy materials to consume laser energy, thereby protecting the substrate;

[0006] 2) Reflective protection: It has high reflective properties, reflects heat, reduces absorption, and thus protects the substrate;

[0007] 3) Thermal insulation protection: Utilizes thermal insulation to block heat transfer, thereby protecting the substrate;

[0008] 4) Composite protection: A protection method that combines two or three of the above protection strategies through simple combination and superposition.

[0009] However, current research on laser protection materials still has some shortcomings. For example:

[0010] 1) Reflective protection primarily using metallic materials involves spraying a metallic protective layer onto a metallic substrate. While this method offers high reflectivity to lasers, its relatively low melting point and susceptibility to oxidation at high temperatures limit its application in high-energy laser protection. Furthermore, these reflective protective materials are often mirror-like, and this mirror structure is easily damaged by lasers, thus losing its high reflectivity.

[0011] 2) Thermal ablation protection based on organic materials involves spraying an organic material protective layer onto the upper part of the metal substrate. However, when dissipating laser energy, it is often accompanied by open flame combustion, causing significant quality loss and contaminating or damaging equipment or precision instruments.

[0012] 3) Thermal barrier coating-based thermal insulation protection involves spraying a thermal barrier coating protective layer onto the upper part of the metal substrate. The low thermal conductivity of the material itself can reduce the temperature of the substrate. However, as the laser loading time increases, the low thermal conductivity causes the area affected by the laser spot to heat up rapidly due to heat accumulation. This leads to thermal ablation damage to the coating and even the substrate material first, and the reduction in thermal conductivity is limited, resulting in low protection efficiency and poor protection effect.

[0013] Given the current development of high-power lasers and the shortcomings of existing laser protection materials, there is an urgent need to propose a novel laser protection material with novel structure and performance, which can take into account multiple optical, thermal, and mechanical coupling effects and buffer the effects of instantaneous local high-temperature fields, thereby achieving the protection requirements of high-efficiency laser protection. Simultaneously, a simple, short-cycle, and low-cost fabrication strategy should be developed to meet the future demand for new structural / functional integrated materials in complex environments. Summary of the Invention

[0014] The main objective of this invention is to provide the application of boron nitride aerogel in the field of laser protection and to provide a corresponding laser protection material to overcome the shortcomings of the prior art.

[0015] Another object of the present invention is to provide a method for laser protection.

[0016] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0017] This invention provides the application of boron nitride aerogel in the field of laser protection.

[0018] Furthermore, the boron nitride aerogel has a three-dimensional porous network structure assembled from boron nitride nano-building units. The three-dimensional porous network structure includes micropores with a pore size of less than 2 nm, mesopores with a pore size of 2 to 50 nm, and macropores with a pore size of 50 nm to 100 μm.

[0019] This invention also provides a laser protection material having a three-dimensional porous network structure assembled from boron nitride nanostructures. The three-dimensional porous network structure includes micropores with a pore size of less than 2 nm, mesopores with a pore size of 2 to 50 nm, and macropores with a pore size of 50 nm to 100 μm. The laser protection material can reflect laser light and manage the local high-temperature field and thermal stress during laser irradiation. Furthermore, the laser protection material can maintain its integrity during continuous laser irradiation.

[0020] This invention also provides a method for preparing a laser protection material, comprising: dissolving a boron source precursor and a nitrogen source precursor in a solvent to obtain a transparent precursor solution, followed by sol-gel transformation, drying and high-temperature pyrolysis to obtain the laser protection material.

[0021] This invention also provides a resin-based laser protection material, comprising: a resin material composited with each other, and a laser protection material serving as an optical enhancer, wherein the resin material is distributed within the three-dimensional porous network structure of the laser protection material.

[0022] The embodiments of the present invention also provide the application of the aforementioned laser protection materials, or resin-based laser protection materials, in the field of laser protection.

[0023] Accordingly, embodiments of the present invention also provide a laser protection method, which includes:

[0024] Provide the aforementioned laser protection material, or resin-based laser protection material;

[0025] The laser protection material or resin-based laser protection material is embedded in the target surface, and laser protection is achieved by irradiating the surface of the laser protection material or resin-based laser protection material with a laser.

[0026] Compared with existing laser protection materials, the advantages of this invention are at least as follows:

[0027] 1) The laser protection material provided by this invention has the characteristics of low density, high reflectivity, high thermal stability, low thermal conductivity, low coefficient of thermal expansion, and flexible porous skeleton. It is a lightweight, high reflectivity, and heat-insulating laser protection material. The lightweight feature can effectively reduce the target's load, which is of great significance for weight reduction of aircraft, etc.; the high reflectivity feature can effectively reflect lasers and reduce the heat deposition of lasers on the material surface; the low thermal conductivity can effectively attenuate the longitudinal transfer of heat on the material surface and protect the target from high temperature damage; the low coefficient of thermal expansion and flexible skeleton feature can ensure that the aerogel material can effectively buffer the thermal stress impact caused by the local high temperature field induced by laser.

[0028] 2) The lightweight, high-reflectivity, and heat-insulating laser protection material provided by this invention can protect against lasers in the visible and infrared bands, and its laser protection power density threshold can reach approximately 9.0 × 10⁻⁶. 4 W / cm 2 ;

[0029] 3) The lightweight, high-reflectivity, and heat-insulating laser protection material provided by this invention can also be used as an optical reinforcement to develop new high-reflectivity and ablation-resistant resin-based laser protection materials;

[0030] 4) The laser protection material provided by this invention has a simple preparation process, mild reaction conditions, is easy to operate, has low energy consumption, and is green and pollution-free. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 These are optical photographs of the laser protection material obtained in Embodiment 1 of the present invention;

[0033] Figure 2 These are scanning electron microscope (SEM) images of the laser protection material obtained in Embodiment 1 of the present invention;

[0034] Figure 3 These are SEM images of the laser protection material obtained in Embodiment 2 of the present invention;

[0035] Figure 4 These are SEM images of the laser protection material obtained in Embodiment 3 of the present invention;

[0036] Figure 5 This is a SEM image of the laser protection material obtained in Example 4 of the present invention;

[0037] Figure 6 This is a SEM image of the laser protection material obtained in Embodiment 5 of the present invention;

[0038] Figure 7 This is a SEM image of the laser protection material obtained in Embodiment 6 of the present invention;

[0039] Figure 8 This is a SEM image of the laser protection material obtained in Embodiment 7 of the present invention;

[0040] Figure 9 This is a SEM image of the laser protection material obtained in Example 8 of the present invention;

[0041] Figure 10 These are transmission electron microscope (TEM) images of the laser protection material obtained in Embodiment 1 of the present invention;

[0042] Figure 11 Here is a SEM image of the boron nitride / polydimethylsiloxane composite material obtained in Example 1 of this invention;

[0043] Figure 12 This is an image of silicon elemental composition of the boron nitride / polydimethylsiloxane composite material obtained in Example 1 of this invention;

[0044] Figure 13 This is the X-ray diffraction (XRD) pattern of the laser protection material obtained in Example 1 of the present invention;

[0045] Figure 14 This is a thermogravimetric curve of the laser protective material obtained in Embodiment 1 of the present invention;

[0046] Figure 15 This is a reflectivity curve of the laser protection material obtained in Embodiment 1 of the present invention;

[0047] Figure 16 This is a thermal expansion strain curve of the laser protection material obtained in Embodiment 1 of the present invention;

[0048] Figure 17 This is a stress-strain cycle curve of the laser protection material obtained in Embodiment 1 of the present invention;

[0049] Figure 18 These are optical photographs of the laser irradiation protection experiment of the laser protection material obtained in Embodiment 1 of the present invention;

[0050] Figure 19 This is a low-magnification SEM image of the laser protective material obtained in Embodiment 1 of the present invention after high-energy laser irradiation;

[0051] Figure 20 This is a high-magnification SEM image of the laser protective material obtained in Embodiment 1 of the present invention after high-energy laser irradiation;

[0052] Figure 21 This is a laser irradiation protection photograph of the boron nitride / polydimethylsiloxane composite material obtained in Example 1 of the present invention. Detailed Implementation

[0053] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention, which mainly provides a laser protection material and its preparation method, as well as a corresponding laser protection method. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0054] One aspect of this invention provides the application of boron nitride aerogel in the field of laser protection. The boron nitride aerogel has a three-dimensional porous network structure assembled from boron nitride nanobuilding units. The three-dimensional porous network structure includes micropores with a pore size of less than 2 nm, mesopores with a pore size of 2 to 50 nm, and macropores with a pore size of 50 nm to 100 μm.

[0055] In some implementations, the morphology of the boron nitride nanobuilding units includes any one or a combination of two or more of the following: fibrous, ribbon-like, irregular bodies, etc., preferably ribbon-like nanobuilding units, but not limited thereto.

[0056] Furthermore, the macroscopic morphology of the boron nitride aerogel includes any one or more combinations of cubes, cylinders, sheets, polyhedra, and spheres, but is not limited thereto.

[0057] Another aspect of the present invention provides a laser protection material, which has the characteristics of low density, high reflectivity, high thermal stability, low thermal conductivity, low coefficient of thermal expansion and flexible porous framework. The laser protection material is an ultralight solid material assembled from boron nitride nanostructures.

[0058] Specifically, the laser protection material has a three-dimensional porous network structure assembled from a large number of boron nitride nanostructures. The three-dimensional porous network structure includes micropores with a pore size of less than 2 nm, mesopores with a pore size of 2 to 50 nm, and macropores with a pore size of 50 nm to 100 μm. The laser protection material can effectively reflect lasers in the visible and near-infrared bands and effectively manage the local high-temperature field and thermal stress during laser irradiation. The laser protection material can maintain its integrity during continuous laser irradiation, and the duration of laser irradiation is 1 second to 1 hour.

[0059] In some implementations, the morphology of the boron nitride nanobuilding units includes any one or a combination of two or more of the following: fibrous, ribbon-like, irregular bodies, etc., preferably ribbon-like nanobuilding units, but not limited thereto.

[0060] Furthermore, the macroscopic morphology of the laser protective material includes any one or more combinations of cubes, cylinders, sheets, polyhedra, and spheres, but is not limited thereto.

[0061] In some embodiments, the density of the laser protective material is 1–600 mg / cm³. 3 .

[0062] Furthermore, the thermal conductivity of the laser protection material is 0.02–0.5 W / mK.

[0063] Furthermore, the laser protection material has a reflectivity of 10% to 99.9% in the visible to near-infrared range.

[0064] Furthermore, the coefficient of thermal expansion of the laser protective material is -5 × 10⁻⁵. -1 ~2×10 -1 / ℃.

[0065] Furthermore, the laser protection material has good mechanical flexibility and can be bent, compressed, and twisted.

[0066] Furthermore, the laser protection power density of the laser protection material is 1.0 to 9 × 10⁻⁶. 4 W / cm 2 .

[0067] Another aspect of the present invention provides a method for preparing a laser protection material, comprising: dissolving a boron source precursor and a nitrogen source precursor in a solvent to obtain a transparent precursor solution, followed by ultrasonic-assisted sol-gel transformation, drying and high-temperature pyrolysis to obtain the laser protection material.

[0068] Furthermore, the boron source precursor includes any one or a combination of two or more of boric acid, diboric acid, boric anhydride, etc., but is not limited thereto.

[0069] Furthermore, the nitrogen source precursor includes any one or a combination of two or more of urea, melamine, cyanuric acid, biuret, dimethyl guanidine, etc., but is not limited thereto.

[0070] Furthermore, the mass ratio of the boron source precursor to the nitrogen source precursor is 10:1 to 1:10.

[0071] Furthermore, the solvent includes any one or a combination of two or more of the following: water, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, acetone, etc., but is not limited thereto.

[0072] Furthermore, the sol-gel transition temperature is -10℃ to 50℃, the sol-gel transition time is 1 min to 1 h, and the ultrasonic power used is 0 to 10 kW.

[0073] Furthermore, the drying method includes any one or a combination of two or more of the following: freeze drying, atmospheric pressure drying, vacuum drying, and supercritical drying, but is not limited thereto.

[0074] Furthermore, the temperature of the high-temperature pyrolysis is 600–1600°C.

[0075] Furthermore, the atmosphere for the high-temperature pyrolysis is any one or a combination of two or more of the following: air, nitrogen, ammonia, argon, and vacuum.

[0076] Furthermore, the high-temperature pyrolysis time is 0.5h to 12h.

[0077] In summary, the laser protection material provided by this invention has a simple preparation process, mild reaction conditions, is easy to operate, has low energy consumption, low cost, is green and pollution-free, and can be mass-produced.

[0078] This invention also provides a laser protection material prepared by the aforementioned method that can serve as an optical enhancer, improving the optical reflectivity of the resin material and enabling the development of novel high-reflectivity, ablation-resistant resin-based laser protection materials. Specifically, a resin-based laser protection material is a composite material of boron nitride and resin, comprising: a resin material that is composited with each other, and a laser protection material serving as an optical enhancer, wherein the resin material is distributed within the three-dimensional porous network structure of the laser protection material.

[0079] Furthermore, the resin material includes any one or a combination of two or more of epoxy resin, silicone resin, phenolic resin, polyamide resin, polyester resin, etc., but is not limited thereto.

[0080] Furthermore, the content of laser protective material in the resin-based laser protective material is 1-95 wt%.

[0081] Furthermore, the method for preparing the resin-based laser protection material includes:

[0082] The laser protection material is impregnated in a resin fluid, and then the resin fluid is introduced into the three-dimensional porous network structure of the laser protection material by means of aerogel capillary force through solution filling and / or melt filling. The resin fluid is then evaporated and / or cured to prepare the resin-based laser protection material.

[0083] Another aspect of the present invention provides the use of the laser protection material, or resin-based laser protection material, in the field of laser protection.

[0084] Another aspect of the present invention provides a laser protection method that specifically includes:

[0085] The aforementioned laser protection material or resin-based laser protection material is embedded in the target surface, and laser protection is achieved by irradiating the surface of the laser protection material or resin-based laser protection material with a laser.

[0086] In some implementation schemes, the laser protection method specifically includes:

[0087] The laser protection material is embedded in the target surface. When the laser irradiates the material surface, the boron nitride nanoparticles backscatter the laser light, reflecting most of the laser energy into the air and weakening the laser energy reaching the target surface. At the same time, the boron nitride nanoparticles themselves have excellent high-temperature thermal stability and can withstand the influence of the local high-temperature field brought about by laser thermal deposition. The flexible porous network effectively buffers the longitudinal transfer of heat and thermal stress impact. Based on the management of the coupling effect between the above-mentioned light, heat and force, laser protection is achieved.

[0088] In other embodiments, the laser protection method may further include:

[0089] Resin-based laser protection materials are embedded in the target surface. When a laser is irradiated onto the surface of the resin-based laser protection material, the laser energy is dissipated on the surface of the composite material by utilizing the backscattering function of the laser by the boron nitride unit and the high-temperature in-situ ceramization reaction and / or vaporization exothermic reaction of the resin under the laser action, thereby achieving laser protection.

[0090] In summary, the laser protection material provided by this invention possesses characteristics such as low density, high reflectivity, high thermal stability, low thermal conductivity, low coefficient of thermal expansion, and a flexible porous framework, making it a lightweight, highly reflective, and heat-insulating laser protection material. Its lightweight nature effectively reduces the target's weight, which is significant for weight reduction in aircraft and similar applications; its high reflectivity effectively reflects laser light, reducing heat deposition on the material surface; its low thermal conductivity effectively attenuates the longitudinal transfer of heat from the material surface, protecting the target from high-temperature damage; and its low coefficient of thermal expansion and flexible framework ensure that the aerogel material effectively buffers the thermal stress impact caused by the localized high-temperature field induced by the laser.

[0091] To make the objectives, technical solutions, and descriptions of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that these embodiments are only illustrative of the invention and are not intended to limit the invention. The technical solutions of the invention are further described in detail below through several embodiments and in conjunction with the accompanying drawings. However, the selected embodiments are only for illustrating the invention and do not limit the scope of the invention.

[0092] Example 1

[0093] (a) Add 1g of boric acid and 1g of melamine to 100mL of aqueous solution and stir in an 85°C water bath until the solution becomes transparent.

[0094] (b) The transparent solution from step (a) was sonicated at 0.1W power for 1 min at -10°C to obtain a white hydrogel.

[0095] (c) The white hydrogel from step (b) is placed in a freeze dryer and freeze-dried to obtain a white bulk material.

[0096] (d) The white block from step (c) was subjected to high-temperature pyrolysis treatment at 600°C in an argon / air atmosphere for 12 hours to obtain laser protection material (lightweight-high reflectivity-heat insulation boron nitride aerogel laser protection material).

[0097] (e) The lightweight, high-reflectivity, and heat-insulating boron nitride aerogel laser protection material from step (d) is impregnated in an organosilicon (such as polydimethylsiloxane) fluid to achieve organosilicon composite filling and curing, thereby obtaining a high-reflectivity and ablation-resistant resin-based laser protection material.

[0098] The structural and performance characterization data of the lightweight, high-reflectivity, and heat-insulating boron nitride aerogel laser protection material obtained in this embodiment are as follows: The specific surface area of ​​this laser protection material is 768 m². 2 / g, its optical photograph is as follows Figure 1 SEM structure as follows Figure 2 Its TEM image is as follows Figure 10 SEM images of boron nitride / polydimethylsiloxane composites are shown below. Figure 11 As shown, the width statistics of its nanoribbons are as follows: Figure 12 Its X-ray diffraction pattern is as follows Figure 13 Its thermogravimetric curve is as follows Figure 14 Its reflectance curve is as follows Figure 15 Its thermal expansion strain curve is as follows Figure 16 Its stress-strain cycle curve is as follows: Figure 17 Optical photographs of laser irradiation protection experiments, such as Figure 18 As shown, the low-magnification SEM image after laser ablation is as follows: Figure 19 High-magnification SEM images, such as Figure 20 Laser irradiation protection photographs of the obtained boron nitride / polydimethylsiloxane composite material are shown below. Figure 21 As shown in Table 1, the relevant physical properties of the laser protection material obtained in this embodiment are shown in Table 1.

[0099] Example 2

[0100] (a) Add 0.2 g boric acid and 2 g melamine to 100 mL methanol solution and stir in an 85 °C water bath until the solution becomes transparent.

[0101] (b) The transparent solution from step (a) was ultrasonically treated at 10 kW power for 1 h at 50 °C to obtain a white hydrogel.

[0102] (c) Place the white hydrogel from step (b) in an ambient pressure environment and dry it under ambient pressure to obtain a white bulk material.

[0103] (d) The white block from step (c) was subjected to high-temperature pyrolysis treatment at 1600℃ under an argon atmosphere for 0.5h to obtain laser protection material (lightweight-high reflectivity-heat insulation boron nitride aerogel laser protection material).

[0104] (e) The lightweight, high-reflectivity, and heat-insulating boron nitride aerogel laser protection material from step (d) is impregnated in an epoxy resin fluid to achieve composite filling and curing of the epoxy resin, thereby obtaining a high-reflectivity and ablation-resistant resin-based laser protection material.

[0105] The SEM image of the laser protection material obtained in this embodiment is as follows: Figure 3 As shown, the relevant physical properties are shown in Table 1.

[0106] Example 3

[0107] (a) Add 2g of boric acid and 0.2g of melamine to 100mL of ethanol solution and stir in an 85°C water bath until the solution becomes transparent.

[0108] (b) The transparent solution from step (a) was subjected to ultrasonic treatment at 100W power for 0.5h at 20°C to obtain a white hydrogel.

[0109] (c) The white hydrogel from step (b) is placed in a supercritical apparatus and dried via supercritical drying to obtain a white bulk material.

[0110] (d) The white block from step (c) is subjected to high-temperature pyrolysis treatment at 1000°C under a nitrogen atmosphere for 3 hours to obtain laser protection material (lightweight-high reflectivity-heat insulation boron nitride aerogel laser protection material).

[0111] (e) The lightweight, high-reflectivity, and heat-insulating boron nitride aerogel laser protection material from step (d) is impregnated in a phenolic resin fluid to achieve composite filling and curing of the phenolic resin, thereby obtaining a high-reflectivity and ablation-resistant resin-based laser protection material.

[0112] The SEM image of the laser protection material obtained in this embodiment is as follows: Figure 4 As shown, the relevant physical properties are shown in Table 1.

[0113] Example 4

[0114] (a) Add 1g boric acid, 1g cyanuric acid and 0.1g urea to 100mL water / tert-butanol solution and stir in an 85°C water bath until the solution becomes transparent.

[0115] (b) The transparent solution from step (a) was subjected to ultrasonic treatment at 30°C and 1W power for 15 minutes to obtain a white hydrogel.

[0116] (c) The white hydrogel from step (b) is placed in a vacuum environment and dried under vacuum to obtain a white bulk material.

[0117] (d) The white block from step (c) is subjected to high-temperature pyrolysis treatment at 900°C in a vacuum atmosphere for 6 hours to obtain laser protection material (lightweight-high reflectivity-heat insulation boron nitride aerogel laser protection material).

[0118] (e) The lightweight, high-reflectivity, and heat-insulating boron nitride aerogel laser protection material from step (d) is impregnated in a polyamide resin fluid to achieve polyamide composite filling and curing, thereby obtaining a high-reflectivity and ablation-resistant resin-based laser protection material.

[0119] The SEM image of the laser protection material obtained in this embodiment is as follows: Figure 5 As shown, the relevant physical properties are shown in Table 1.

[0120] Example 5

[0121] (a) Add 1g of boric anhydride and 1g of dimethyl guanidine to 100mL of isopropanol solution and stir in a water bath at 85°C until the solution becomes transparent.

[0122] (b) The transparent solution from step (a) was subjected to ultrasonic treatment at 1kW power for 20 minutes at 40°C to obtain a white hydrogel.

[0123] (c) The white hydrogel from step (b) is placed in a freeze dryer and freeze-dried to obtain a white bulk material.

[0124] (d) The white block from step (c) is subjected to high-temperature pyrolysis treatment at 1200°C in an ammonia atmosphere for 10 hours to obtain laser protection material (lightweight-high reflectivity-heat insulation boron nitride aerogel laser protection material).

[0125] (e) The lightweight, high-reflectivity, and heat-insulating boron nitride aerogel laser protection material from step (d) is impregnated in a polyester resin fluid to achieve composite filling and curing of the polyester resin, thereby obtaining a high-reflectivity and ablation-resistant resin-based laser protection material.

[0126] The SEM image of the laser protection material obtained in this embodiment is as follows: Figure 6 As shown, the relevant physical properties are shown in Table 1.

[0127] Example 6

[0128] (a) Add 1g of diboric acid and 1g of melamine to 100mL of aqueous solution and stir in an 85°C water bath until the solution becomes transparent.

[0129] (b) The transparent solution from step (a) was subjected to ultrasonic treatment at 10°C and 500W for 10 minutes to obtain a white hydrogel.

[0130] (c) The white hydrogel from step (b) is placed in a freeze dryer and freeze-dried to obtain a white bulk material.

[0131] (d) The white block from step (c) was subjected to high-temperature pyrolysis treatment at 1300℃ in an argon / ammonia atmosphere for 8 hours to obtain laser protection material (lightweight-high reflectivity-heat insulation boron nitride aerogel laser protection material).

[0132] (e) The lightweight, high-reflectivity, and heat-insulating boron nitride aerogel laser protection material from step (d) is impregnated in an organosilicon (such as polydimethylsiloxane) fluid to achieve organosilicon composite filling and curing, thereby obtaining a high-reflectivity and ablation-resistant resin-based laser protection material.

[0133] The SEM image of the laser protection material obtained in this embodiment is as follows: Figure 7 As shown, the relevant physical properties are shown in Table 1.

[0134] Example 7

[0135] (a) Add 1g of boric acid and 1g of melamine to 100mL of acetone solution and stir in a water bath at 85°C until the solution becomes transparent.

[0136] (b) The transparent solution from step (a) was subjected to ultrasonic treatment at 30°C and 10W power for 40 minutes to obtain a white hydrogel.

[0137] (c) The white hydrogel from step (b) is placed in a freeze dryer and freeze-dried to obtain a white bulk material.

[0138] (d) The white block from step (c) is subjected to high-temperature pyrolysis treatment at 900°C under an argon atmosphere for 0.5 h to obtain laser protection material (lightweight-high reflectivity-heat insulation boron nitride aerogel laser protection material).

[0139] (e) The lightweight, high-reflectivity, and heat-insulating boron nitride aerogel laser protection material from step (d) is impregnated in an organosilicon (such as polydimethylsiloxane) fluid to achieve organosilicon composite filling and curing, thereby obtaining a high-reflectivity and ablation-resistant resin-based laser protection material.

[0140] The SEM image of the laser protection material obtained in this embodiment is as follows: Figure 8 As shown, the relevant physical properties are shown in Table 1.

[0141] Example 8

[0142] (a) Add 1g of boric acid and 1g of melamine to 100mL of n-butanol / water solution and stir in an 85°C water bath until the solution becomes transparent.

[0143] (b) The transparent solution from step (a) was sonicated at 150W for 15 minutes at 20°C to obtain a white hydrogel.

[0144] (c) The white hydrogel from step (b) is placed in a freeze dryer and freeze-dried to obtain a white bulk material.

[0145] (d) The white block from step (c) is subjected to high-temperature pyrolysis treatment at 1100°C in a nitrogen / air atmosphere for 12 hours to obtain laser protection material (lightweight-high reflectivity-heat insulation boron nitride aerogel laser protection material).

[0146] (e) The lightweight, high-reflectivity, and heat-insulating boron nitride aerogel laser protection material from step (d) is impregnated in an organosilicon (such as polydimethylsiloxane) fluid to achieve organosilicon composite filling and curing, thereby obtaining a high-reflectivity and ablation-resistant resin-based laser protection material.

[0147] The SEM image of the laser protection material obtained in this embodiment is as follows: Figure 9 As shown, the relevant physical properties are shown in Table 1.

[0148] Table 1. Test performance parameters of the laser protection materials prepared in Examples 1-8

[0149]

[0150] In addition, the inventors of this invention also used other raw materials and process conditions listed in this specification, and prepared a series of laser protection materials with reference to Examples 1-8. Testing revealed that these laser protection materials also possess the excellent properties described in this specification. The foregoing examples demonstrate that the laser protection materials of this invention exhibit excellent performance, superior flexibility and elastic recovery properties, require simple preparation equipment, significantly shorten the preparation cycle and reduce costs, and have enormous application potential.

[0151] It should be understood that the above descriptions are only some embodiments of the present invention. It should be noted that those skilled in the art can make other modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. Application of boron nitride aerogel in the field of laser protection, wherein the boron nitride aerogel has a three-dimensional porous network structure assembled from boron nitride nano-building units, wherein the three-dimensional porous network structure includes micropores with a pore size of less than 2 nm, mesopores with a pore size of 2~50 nm, and macropores with a pore size of 50 nm~100 μm; The preparation method of the boron nitride aerogel includes: Boron source precursors and nitrogen source precursors are dissolved in a solvent to obtain a transparent precursor solution, which is then subjected to sol-gel transformation, drying, and high-temperature pyrolysis to obtain boron nitride aerogel. The boron source precursor is boric acid or diboric acid, and the nitrogen source precursor is melamine. The mass ratio of the boron source precursor to the nitrogen source precursor is 1:1 to 1:

10. The sol-gel transformation is an ultrasound-assisted transformation at a temperature of -10 °C to 50 °C, a transformation time of 1 min to 1 h, and an ultrasonic power of 0.1 W to 10 kW. The high-temperature pyrolysis temperature is 600 to 1600 °C, and the atmosphere for high-temperature pyrolysis is argon, a mixture of air and argon, or a mixture of ammonia and argon. The high-temperature pyrolysis time is 0.5 h to 12 h.

2. The application according to claim 1, characterized in that: The morphology of the boron nitride nanobuilding units includes any one or a combination of two or more of the following: fibrous, ribbon-like, and irregular bodies.

3. The application according to claim 2, characterized in that: The boron nitride nanobuilding units are in the form of ribbon-like nanobuilding units.

4. The application according to claim 1, characterized in that: The macroscopic morphology of the boron nitride aerogel includes any one or more combinations of cubes, cylinders, sheets, polyhedra, and spheres.

5. The application according to claim 1, characterized in that: The solvent is selected from any one or a combination of two or more of water, methanol, and acetone.

6. The application according to claim 1, characterized in that: The drying method is selected from one or a combination of two of freeze drying and atmospheric pressure drying.

7. A laser protection method, characterized in that, include: Provide laser protection materials, or resin-based laser protection materials; The laser protection material or resin-based laser protection material is embedded in the target surface, and the surface of the laser protection material or resin-based laser protection material is irradiated with a laser to achieve laser protection. The laser protection material is boron nitride aerogel, which has a three-dimensional porous network structure assembled from boron nitride nano-building units. The three-dimensional porous network structure includes micropores with a pore size of less than 2 nm, mesopores with a pore size of 2 to 50 nm, and macropores with a pore size of 50 nm to 100 μm. The resin-based laser protection material comprises: a composite resin material and a laser protection material serving as an optical enhancer, wherein the resin material is distributed within the three-dimensional porous network structure of the laser protection material; the resin material is selected from any one or a combination of two of epoxy resin and polydimethylsiloxane. The preparation method of the boron nitride aerogel includes: Boron source precursors and nitrogen source precursors are dissolved in a solvent to obtain a transparent precursor solution, which is then subjected to sol-gel transformation, drying, and high-temperature pyrolysis to obtain boron nitride aerogel. The boron source precursor is boric acid or diboric acid, and the nitrogen source precursor is melamine. The mass ratio of the boron source precursor to the nitrogen source precursor is 1:1 to 1:

10. The sol-gel transformation is an ultrasound-assisted transformation at a temperature of -10 °C to 50 °C, a transformation time of 1 min to 1 h, and an ultrasonic power of 0.1 W to 10 kW. The high-temperature pyrolysis temperature is 600 to 1600 °C, and the atmosphere for high-temperature pyrolysis is argon, a mixture of air and argon, or a mixture of ammonia and argon. The high-temperature pyrolysis time is 0.5 h to 12 h.

8. The laser protection method according to claim 7, characterized in that, The method for preparing the resin-based laser protection material includes: immersing the laser protection material in a resin fluid, and then introducing the resin fluid into the three-dimensional porous network structure of the laser protection material through solution filling and / or melt filling, followed by solvent evaporation and / or curing to obtain the resin-based laser protection material.

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