Preparation method of modified porous ceramic wave-transparent material and application thereof

Abstract

The present application relates to a kind of modified porous ceramic wave-transparent material and its preparation method and application.The method is with porous ceramic wave-transparent material as base material, then impregnation composite impregnation liquid, subsequent processing is carried out, finally the material with better ablation resistance is obtained.In the present application, composite impregnation liquid is polysilazane as base liquid, add various fillers and reagents and process to obtain composite impregnation liquid.The base material is impregnated and post-treated using composite impregnation liquid, so that the ablation resistance of base material is improved.The method of the present application can obtain ceramic wave-transparent material with excellent ablation resistance at lower cost, can effectively improve the performance of composite material especially ablation resistance while not affecting the wave-transparent performance of base material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-temperature-resistant and ablation-resistant materials, and particularly relates to a preparation method and application of a modified porous ceramic-based wave-transparent material. BACKGROUND

[0002] With the continuous development of aircraft technology, the flight speed of aircraft is getting faster and faster, the working environment is becoming more and more severe, and the aerodynamic heating is more serious, which continuously increases the requirement for the temperature resistance of materials. In order to enable the communication system of the aircraft to normally work in the new working environment, the wave-transparent material needs to have the properties of high-temperature resistance, ablation resistance, excellent mechanical properties and wave-transparent performance, etc.

[0003] Common high-temperature-resistant wave-transparent materials mainly include quartz, alumina, mullite, silicon nitride and boron nitride, etc. These wave-transparent materials have certain temperature resistance. Among them, the temperature resistance of quartz materials is generally not more than 1100 DEG C, the temperature resistance of alumina and mullite materials is generally about 1200 DEG C, and the temperature resistance of silicon nitride and boron nitride can be 1400 DEG C and above.

[0004] Based on the development demand of light weight, these wave-transparent materials generally have porous characteristics. In other words, these wave-transparent materials are generally porous ceramic-based wave-transparent materials.

[0005] Based on the need for excellent mechanical properties, the toughness of these materials is usually improved by fiber reinforcement, so as to obtain wave-transparent materials with better comprehensive performance.

[0006] Quartz fiber reinforced composite material is a relatively mature ceramic-based wave-transparent material, which has excellent comprehensive properties of force, heat and electricity, and the cost is relatively low compared with silicon nitride fiber reinforced composite material and boron nitride fiber reinforced composite material. However, the temperature resistance of quartz fiber reinforced composite material is low, which limits its application at higher temperatures.

[0007] Silicon nitride fiber reinforced composite material has the characteristics of excellent comprehensive performance, and the long-time use temperature is more than 1400 DEG C, which is a promising high-temperature wave-transparent material. However, due to the high cost of raw material fibers and precursors, as well as the requirement of high temperature, high pressure and atmosphere in the preparation process, the cost of silicon nitride fiber reinforced composite material is high, which is difficult to popularize on a large scale. Similarly, the cost of boron nitride fiber reinforced composite material is higher, which is more difficult to popularize.

[0008] If the quartz, alumina, mullite and other ceramic-based wave-transparent materials can be modified and treated, the wave-transparent performance of the ceramic-based wave-transparent materials can be ensured, and the ceramic-based wave-transparent materials can have the performance of resisting higher temperature ablation, which will have very important significance for the development of the ceramic-based wave-transparent materials.

[0009] Therefore, it is urgent to provide a method capable of improving the high-temperature ablation performance of existing ceramic wave-transparent materials while ensuring the wave-transparency and light weight of the ceramic wave-transparent materials. SUMMARY

[0010] In order to solve the above technical problems existing in the existing ceramic wave-transparent materials, the application provides a preparation method of a porous ceramic wave-transparent material and application thereof, and the porous ceramic wave-transparent material has excellent comprehensive performance, especially improved ablation resistance.

[0011] In a first aspect, the application provides a preparation method of a porous ceramic wave-transparent material, which comprises the following steps:

[0012] (1) uniformly mixing boron nitride powder, boron oxide powder and a surface modifier to obtain a basic filler;

[0013] (2) adding the basic filler and a defoaming agent into polysilazane and uniformly mixing, and then performing grinding and filtering to obtain a composite impregnation liquid;

[0014] (3) using the composite impregnation liquid to impregnate and dry a substrate material, and then solidifying to obtain a solidified preform;

[0015] (4) performing heat treatment on the solidified preform to obtain a modified porous ceramic wave-transparent material.

[0016] Preferably, the mass ratio of the surface modifier to the boron nitride powder is (2-20):100; and / or the mass ratio of the surface modifier to the boron oxide powder is (3-30):100.

[0017] Preferably, the mass ratio of the basic filler to the polysilazane is (5-30):100; and / or the mass ratio of the defoaming agent to the polysilazane is (0.5-3):100.

[0018] Preferably, the surface modifier is one or more of organic silicone resin, dopamine and silane coupling agent; the defoaming agent is one or more of polyether defoaming agent, organic silicon defoaming agent and polyether modified organic silicon defoaming agent; and / or the ceramic yield of the polysilazane is not less than 60%, and the viscosity of the polysilazane is 50-500 cP.

[0019] Preferably, the grinding is manual grinding or grinding using a grinding device, the speed of the grinding is 10-100 r / min, and the time of the grinding is 1-10 min.

[0020] Preferably, the filtering is manual filtering or filtering using filtering facilities, and the filtering precision is 1-10 μm.

[0021] Preferably, the impregnation process is atmospheric pressure impregnation, vacuum impregnation and / or pressure impregnation, and the impregnation time is 10-60 min.

[0022] Preferably, the impregnation-drying is repeated for 3-15 times; the solidification is carried out in a nitrogen atmosphere, preferably, ultrasonic treatment is introduced during the solidification; and / or the heat treatment is carried out in a nitrogen atmosphere, preferably, during the temperature rise to the heat treatment temperature, the nitrogen flow rate increases with the temperature rise, the initial nitrogen flow rate is 1-2 L / min, the nitrogen flow rate increases at a rate of 0.1-0.2 L / min, and when the heat treatment temperature is reached, the nitrogen flow rate is 10-20 L / min and the heat treatment is carried out at this nitrogen flow rate.

[0023] Preferably, the solidification temperature is 160-230℃; and / or the heat treatment temperature is 550-650℃.

[0024] Preferably, the boron nitride powder and / or boron oxide powder is micron-level powder, sub-micron-level powder or nano-level powder; and / or the purity of the boron nitride powder and / or boron oxide powder is not less than 99%.

[0025] Preferably, the base material is a porous ceramic wave-transparent material; preferably, the porous ceramic wave-transparent material is one or more of quartz fiber reinforced composite material, mullite fiber reinforced composite material, alumina fiber reinforced composite material, quartz ceramic material, mullite ceramic material and alumina ceramic material; preferably, the porosity of the porous ceramic wave-transparent material is 30-60%.

[0026] The present application provides, in a second aspect, a modified porous ceramic wave-transparent material, which is prepared by the method of the first aspect of the present application.

[0027] The present application provides, in a third aspect, the use of the porous ceramic wave-transparent material of the second aspect of the present application as a wave-transparent material for high-speed aircraft.

[0028] Compared with the prior art, the present application has at least the following beneficial effects:

[0029] (1) The method of the present application adds various fillers to polysilazane to form a composite impregnating solution, and modifies the base material by impregnation, thereby obtaining a high-temperature-resistant, oxidation-resistant, and ablation-resistant wave-transparent material with excellent ablation-resistant and wave-transparent properties, which can effectively improve the ablation-resistant and high-temperature-resistant properties of the base material. The polysilazane in the composite impregnating solution has good high-temperature resistance and good oxidation resistance, boron nitride has better high-temperature resistance and wave-transparent properties, and the presence of boron oxide makes the material have better oxidation resistance. The presence of other additives in the composite impregnating solution plays an important role in the uniformity of the composite impregnating solution. The surface modifier can effectively improve the compatibility between the inorganic filler and the organic base solution, and the defoaming agent can effectively improve the problem that bubbles in the high-viscosity composite impregnating solution are not easy to eliminate and defects are easy to occur. The method of the present application can obtain a wave-transparent material with excellent ablation resistance at a low cost.

[0030] (2) The present application solves the problem of high-temperature resistance and ablation resistance of ceramic-based wave-transparent materials by impregnation modification, which can effectively protect the internal base material and reduce the possibility of damage in a high-temperature oxygen-containing and airflow scouring environment, thereby improving the temperature resistance level and enhancing the ablation resistance of the base material.

[0031] (3) The present application uses a main raw material, polysilazane, which has a low price and does not require high pressure and an ammonia atmosphere in the process, so it can achieve higher temperature ablation resistance at a very low cost, which has important promotional significance. Compared with directly using silicon nitride fiber reinforced composite materials, it has the characteristics of low cost and low implementation difficulty, and has wider application. The method of the present application can not only be applied to quartz fiber reinforced composite materials, but also be popularized to mullite fiber reinforced composite materials, alumina fiber reinforced composite materials, and various ceramic wave-transparent materials such as quartz ceramic, mullite ceramic, and alumina ceramic, for improving their temperature resistance level and enhancing their ablation resistance, which has good promotional prospects. DETAILED DESCRIPTION

[0032] The present application will be further described below by way of some specific embodiments. However, it should be understood that the protection scope of the present application is not limited to these specific embodiments.

[0033] As described above, the present application provides, in a first aspect, a preparation method of a modified porous ceramic-based wave-transparent material, the preparation method comprising the following steps:

[0034] (1) uniformly mixing boron nitride powder, boron oxide powder, and a surface modifier to obtain a base filler;

[0035] (2) adding the base filler and defoaming agent into polysilazane and mixing uniformly, then grinding and filtering to obtain a composite impregnation solution;

[0036] (3) curing after impregnation and drying of the base material using the composite impregnation solution to obtain a cured preform;

[0037] (4) heat treating the cured preform to obtain a modified porous ceramic wave-transparent material.

[0038] In the present application, the "impregnation and drying" refers to impregnation and drying. The temperature of the drying is, for example, room temperature 20-30 DEG C, and the drying time is, for example, 4-8 h. In the present application, the modified porous ceramic wave-transparent material is obtained after multiple "impregnation and drying", curing and heat treating.

[0039] The method of the present application uses polysilazane as the base liquid, adds various fillers into polysilazane to form a composite impregnation solution, and modifies by impregnation to obtain a ceramic wave-transparent material with excellent high-temperature resistance, oxidation resistance, ablation resistance and wave-transparent performance, which can effectively improve the high-temperature resistance and ablation resistance of the base material. The polysilazane in the composite impregnation solution of the present application has good high-temperature resistance and better oxidation resistance, boron nitride has better high-temperature resistance and wave-transparent performance, and the presence of boron oxide makes the material have better oxidation resistance. The presence of other additives in the composite impregnation solution of the present application plays an important role in the uniformity of the composite impregnation solution. The surface modifier can effectively improve the compatibility between the inorganic filler and the organic base liquid, and the defoaming agent can effectively solve the problem that bubbles in the high-viscosity composite impregnation solution are not easy to eliminate and defects are easy to occur. The method of the present application can obtain a wave-transparent material with excellent high-temperature resistance and ablation resistance at a lower cost.

[0040] The present application solves the problem of high-temperature resistance and ablation resistance of the ceramic wave-transparent material by impregnation modification, which can effectively protect the internal base material and reduce the possibility of damage in a high-temperature oxygen-containing and airflow scouring environment, and can improve the temperature resistance grade and enhance the ablation resistance of the base material. Compared with directly using silicon nitride fiber reinforced composite material, the present application has the characteristics of low cost and small implementation difficulty, and has a wider application.

[0041] According to some preferred embodiments, the mass ratio of the surface modifier to the boron nitride powder is (2-20):100 (e.g., 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, 11:100, 12:100, 13:100, 14:100, 15:100, 16:100, 17:100, 18:100, 19:100, or 20:100). In some more preferred embodiments, the mass ratio of the surface modifier to the boron nitride powder is (8-12):100 (e.g., 8:100, 9:100, 10:100, 11:100, or 12:100).

[0042] According to some preferred embodiments, the mass ratio of the surface modifier to the boron oxide powder is (3-30):100 (e.g., 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, 11:100, 12:100, 13:100, 14:100, 15:100, 16:100, 17:100, 18:100, 19:100, 20:100, 21:100, 22:100, 23:100, 24:100, 25:100, 26:100, 27:100, 28:100, 29:100, or 30:100). In some more preferred embodiments, the mass ratio of the surface modifier to the boron oxide powder is (12-18):100 (e.g., 12:100, 15:100, or 18:100).

[0043] The present application has obtained the optimal proportioning of the components in the base filler, i.e., the mass ratio of the surface modifier to the boron nitride powder is (8-12):100, and the mass ratio of the surface modifier to the boron oxide powder is (12-18):100, through a large number of creative experiments. Under the optimal proportioning, a high-temperature resistant ablation-resistant and wave-transparent material with better high-temperature resistance, ablation resistance, and wave transmission performance can be advantageously obtained. One of the reasons why the optimal proportioning can achieve better performance is that, by adding boron nitride powder, boron oxide powder, and surface modifier in appropriate amounts in the base filler, on the one hand, the performance advantages of the boron nitride powder and the boron oxide powder can be more effectively brought into play, and on the other hand, the introduction of the surface modifier in a specific mass ratio can more effectively improve the dispersibility of the boron nitride powder and the boron oxide powder, so that the powder filler can be more easily and uniformly distributed in the composite filler, reducing the possibility of agglomeration and uneven particle dispersion, and more effectively improving the compatibility between the inorganic filler and the organic base liquid, thereby helping to enhance the adhesion between the composite impregnated liquid and the base material, and finally ensuring the improvement of the overall stability, uniformity, and compactness of the material, and further helping to prepare a high-quality high-temperature resistant ablation-resistant and wave-transparent material.

[0044] According to some preferred embodiments, the mass ratio of the base filler to the polysilazane is (5-30): 100 (e.g., 5: 100, 10: 100, 15: 100, 20: 100, 25: 100, or 30: 100). In some more preferred embodiments, the mass ratio of the defoaming agent to the polysilazane is (0.03-0.3): 100 (e.g., 0.03: 100, 0.05: 100, 0.1: 100, 0.2: 100, or 0.3: 100).

[0045] According to some preferred embodiments, the mass ratio of the base filler to the polysilazane is (5-30): 100, more preferably (10-20): 100. According to some preferred embodiments, the mass ratio of the defoaming agent to the polysilazane is (0.03-0.3): 100, more preferably (0.05-0.2): 100. In these embodiments, the mass ratio of the base filler, the polysilazane, and the defoaming agent within the above ranges can be more conducive to obtaining a high-temperature resistant ablative wave-transparent material with better high-temperature resistance, better ablative resistance, and better wave-transparent performance. The inventors have found that an appropriate amount of defoaming agent helps to reduce the number of air holes in the composite impregnating liquid, which positively affects the density and uniformity of the material and is conducive to reducing the negative impact of air holes in the material on wave-transparent performance. An appropriate amount of defoaming agent also helps the composite impregnating liquid to impregnate the base material more uniformly, thereby helping to reduce defects in the material. An appropriate amount of defoaming agent also helps to maintain good adhesion between the composite impregnating liquid and the base material. If the amount of defoaming agent is insufficient, it can result in bubbles in the composite impregnating liquid that are difficult to eliminate. If the amount of defoaming agent is too much, it can cause the viscosity of the composite impregnating liquid to decrease sharply, making it difficult to adhere firmly to the base material, thereby affecting the improvement of the high-temperature resistant ablative wave-transparent performance.

[0046] According to some preferred embodiments, the surface modifier includes but is not limited to organosilicon resins, dopamine, silane coupling agents, etc. In some more preferred embodiments, the surface modifier is one or more of organosilicon resin, dopamine, and silane coupling agent.

[0047] According to some preferred embodiments, the defoaming agent includes but is not limited to polyether, organosilicon, polyether-modified organosilicon, etc. In some more preferred embodiments, the defoaming agent is one or more of polyether defoaming agent, organosilicon defoaming agent, and polyether-modified organosilicon defoaming agent.

[0048] According to some preferred embodiments, the ceramic yield of the polysilazane is not less than 60% (e.g. not less than 65% or 70%), and the viscosity of the polysilazane is 50 cP to 500 cP (e.g. 60, 70, 80, 90, 100, 200, 300, 400 or 500 cP).

[0049] The present application does not make specific limitation on the source of each raw material, and products available on the market or products synthesized by existing methods can be used.

[0050] According to some preferred embodiments, the grinding is manual grinding or grinding using a grinding device, the speed of which can be 10 r / min to 100 r / min (e.g. 20, 30, 40, 50, 60, 70, 80 or 90 r / min), and the time of which can be 1 min to 10 min (e.g. 2, 3, 4, 5, 6, 7, 8 or 9 min).

[0051] According to some preferred embodiments, the filtering is manual filtering or filtering using a filtering device, the accuracy of which can be 1 μm to 10 μm (e.g. 1 μm, 5 μm or 10 μm).

[0052] According to some preferred embodiments, the number of times of repeating the dipping and drying is 3 to 15 (e.g. 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15).

[0053] According to some preferred embodiments, the dipping is atmospheric pressure dipping, vacuum dipping and / or pressure dipping, and the time of which can be 10 min to 60 min (e.g. 20, 30, 40 or 50 min).

[0054] According to some preferred embodiments, the solidification is performed in a nitrogen atmosphere, and the present application does not make specific limitation on the flow rate of nitrogen during the solidification, and it is only required that the solidification is performed in a nitrogen atmosphere. For example, it can be performed in a static nitrogen atmosphere. Preferably, ultrasonic treatment is introduced during the solidification. More preferably, interval ultrasonic treatment is performed during the solidification. For example, ultrasonic treatment is performed every 10 min to 30 min (e.g. every 15, 20 or 25 min) for 1 min to 5 min (e.g. 2, 3 or 4 min), and the frequency of the ultrasonic treatment can be 20 kHz to 40 kHz (e.g. 25, 30 or 35 kHz).

[0055] The present application finds that, during the curing stage, proper ultrasonic treatment does not affect the performance of the material, but helps to improve the uniformity, density and quality of the material, and further eliminates pores in the composite impregnating liquid, and improves the density of the material. The present application also finds that the ultrasonic treatment during the curing stage can make the impregnating liquid adhere more firmly to the substrate, and the ultrasonic treatment during the curing stage of the present application can improve the structure and performance of the material before heat treatment, thereby preparing for high-temperature heat treatment in advance, which helps to improve the stability, ablation resistance and wave transmission performance of the high-temperature resistant and ablation resistant wave-transparent material.

[0056] According to some preferred embodiments, the heat treatment is carried out in a nitrogen atmosphere, preferably, during the process of increasing the temperature to the heat treatment temperature, the flow rate of the nitrogen is increased with the increase of the temperature. For example, the initial flow rate of the nitrogen can be 1-2 L / min, the increasing rate of the flow rate of the nitrogen can be 0.1-0.2 L / min, and when the temperature of the heat treatment is reached, the flow rate of the nitrogen can reach 10-20 L / min and the heat treatment is carried out at this flow rate. Preferably, after the end of the heat treatment, the flow rate of the nitrogen is decreased to 0 L / min at a rate of 0.2-0.5 L / min, i.e. until the supply of the nitrogen atmosphere is stopped.

[0057] According to some preferred embodiments, the flow rate of the nitrogen is regulated during the heat treatment, which can promote the uniform penetration of the nitrogen atmosphere into the material, help to remove possible pores and loose parts, and further improve the quality and density of the material. After the end of the heat treatment, the flow rate of the nitrogen is gradually reduced to achieve the atmosphere switching, which helps to prevent sudden atmosphere change and thermal shock, helps to maintain the stability of the material, and thus helps to improve the high-temperature resistant and ablation resistant performance of the material and maintain the wave transmission performance.

[0058] According to some preferred embodiments, the temperature of the curing is 160-230 °C (for example, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C or 230 °C). In some more preferred embodiments, the temperature of the heat treatment is 550-650 °C (for example, 550 °C, 600 °C or 650 °C).

[0059] In the present application, the time of the curing can be determined according to the curing state of the selected raw material. Too short time may result in incomplete curing and stickiness, and too long time may result in over-curing and hardness, both of which can adversely affect the performance of the material. The time of the curing may, for example, be 2-10 h (for example, 3, 4, 5, 6, 7, 8 or 9 h).

[0060] In the present application, the time of heat treatment can be determined according to the heat treatment state of the raw material selected, and needs to be substantially complete so that the volatile small molecules can be more fully released, thereby avoiding the adverse phenomena such as delamination and bulging during subsequent high-temperature use. In some preferred embodiments, the time of heat treatment can be, for example, 1 h to 5 h (for example, 2, 3, or 4 h).

[0061] According to some preferred embodiments, the boron nitride powder and / or the boron oxide powder is a micron-level powder, a sub-micron-level powder, or a nano-level powder. In some further preferred or further preferred embodiments, the purity of the boron nitride powder and / or the boron oxide powder is not less than 99%.

[0062] According to some preferred embodiments, the boron nitride powder is micron-level, sub-micron-level, and / or nano-level particles with a purity of ≥99%, and the boron oxide powder is micron-level, sub-micron-level, and / or nano-level particles with a purity of ≥99%.

[0063] According to some preferred embodiments, the base material is a porous ceramic wave-transparent material, which includes but is not limited to materials with silica, alumina, and / or mullite as the main component, and the porosity of the porous ceramic wave-transparent material can generally be 30% to 60% (for example, 35, 40, 45, 50, or 55%).

[0064] According to some preferred embodiments, the ceramic wave-transparent material can be one or more of a quartz fiber reinforced composite material, a mullite fiber reinforced composite material, an alumina fiber reinforced composite material, a quartz ceramic material, a mullite ceramic material, and an alumina ceramic material. In this case, as described above, the porosity of the porous ceramic wave-transparent material can be 30% to 60%.

[0065] According to some specific embodiments, the preparation of the modified porous ceramic wave-transparent material includes the following steps:

[0066] ① Remove the excess particles on the surface of the base material by air flow scouring or the like.

[0067] ② Mix the boron nitride powder, the boron oxide powder, and the surface modifier uniformly to form a base filler.

[0068] ③ Add the base filler and the defoaming agent to the polysilazane and mix uniformly, then perform grinding and filtration to form a composite impregnation solution.

[0069] ④ Use the composite impregnation solution to impregnate and dry the base material multiple times, then solidify, and then perform heat treatment to finally obtain the modified porous ceramic wave-transparent material.

[0070] The application provides a modified porous ceramic-based wave-transparent material in a second aspect.

[0071] The application provides application of the modified porous ceramic-based wave-transparent material in the second aspect to a wave-transparent material of a high-speed aircraft in a third aspect.

[0072] The application will be further described below in combination with some embodiments of the application. However, it should be understood that the embodiments are only used to exemplify the preferred embodiments of the application, and the protection scope of the application should not be interpreted as being limited to the embodiments.

[0073] Embodiment 1

[0074] ①The surface of quartz fiber reinforced composite material (base material) with a thickness of 10 mm and a porosity of 45% is subjected to airflow scouring to remove excess particles on the surface.

[0075] ②Boron nitride powder (average particle size of 200 nm, purity ≥ 99%), boron oxide powder (average particle size of 500 nm, purity ≥ 99%) and a surface modifier (silane coupling agent KH792) are uniformly mixed according to a mass ratio (denoted as mass ratio A for short) of boron nitride powder, boron oxide powder and the surface modifier of 100:66:10 to form a base filler.

[0076] ③The base filler and a defoaming agent (polyether modified organosilicon defoaming agent HY-6811) are added into polysilazane (ceramic yield of 65%, viscosity of 300 cP) and uniformly mixed, then grinded at a speed of 30 r / min for 5 min, and then filtered at a precision of 5 μm to form a composite impregnation solution, wherein the mass ratio (denoted as mass ratio B for short) of the polysilazane, the base filler and the defoaming agent is 100:15:0.1.

[0077] ④The base material surface is impregnated and dried using the composite impregnation solution, and the impregnation and drying are repeated for 8 times in sequence, the pressure for impregnation is normal pressure, the time for each impregnation is 30 min, the temperature for drying is room temperature 25 ℃, the time for each drying is 5 h, then the temperature is increased from room temperature 25 ℃ to 600 ℃ at a rate of 5 ℃ / min, the nitrogen gas atmosphere with a flow rate of 12.5 L / min is used for heat treatment at 600 ℃ for 2 h, after the heat treatment is completed, the nitrogen gas source is turned off, and the temperature is naturally decreased to room temperature 25 ℃, finally, the modified porous ceramic-based wave-transparent material is obtained.

[0078] Embodiment 2

[0079] Example 2 is substantially the same as Example 1, except that in step IV, the impregnation-drying is repeated 4 times successively.

[0080] Example 3

[0081] Example 3 is substantially the same as Example 1, except that in step IV, the impregnation-drying is repeated 12 times successively.

[0082] Example 4

[0083] Example 4 is substantially the same as Example 1, except that in step II, the mass ratio of boron nitride powder, boron oxide powder and surface modifier (denoted as mass ratio A) is 100:66:3.

[0084] Example 5

[0085] Example 5 is substantially the same as Example 1, except that in step II, the mass ratio of boron nitride powder, boron oxide powder and surface modifier (denoted as mass ratio A) is 100:66:20.

[0086] Example 6

[0087] Example 6 is substantially the same as Example 1, except that in step III, the mass ratio of polysilazane, base filler and defoaming agent (denoted as mass ratio B) is 100:15:0.05.

[0088] Example 7

[0089] Example 7 is substantially the same as Example 1, except that in step III, the mass ratio of polysilazane, base filler and defoaming agent (denoted as mass ratio B) is 100:15:0.2.

[0090] Example 8

[0091] Example 8 is substantially the same as Example 1, except that in step IV, during the curing process, ultrasonic treatment is performed every 25 min for 5 min, and the frequency of the ultrasonic treatment is 25 kHz.

[0092] Example 9

[0093] Example 9 is substantially the same as Example 1, except that in step IV, during the heat treatment, the flow rate of the nitrogen gas is increased as the temperature increases, the initial flow rate of the nitrogen gas is 1 L / min, the increasing rate of the flow rate of the nitrogen gas is 0.1 L / min, when reaching 600℃, the flow rate of the nitrogen gas is 12.5 L / min and the 600℃ heat treatment is carried out for 2h at the flow rate of the nitrogen gas, after the heat treatment, the flow rate of the nitrogen gas is decreased to 0 L / min at a rate of 0.25 L / min and then the nitrogen gas source is closed, at the same time, after the heat treatment, the temperature is naturally decreased to room temperature 25℃, and finally the modified porous ceramic wave-transparent material is obtained.

[0094] Example 10

[0095] Example 10 is substantially the same as Example 1, except that in step IV, during the solidification, ultrasonic treatment is carried out every 25 min for 5 min, the frequency of the ultrasonic treatment is 25 kHz; during the heat treatment, the flow rate of the nitrogen gas is increased as the temperature increases, the initial flow rate of the nitrogen gas is 1 L / min, the increasing rate of the flow rate of the nitrogen gas is 0.1 L / min, when reaching 600℃, the flow rate of the nitrogen gas is 12.5 L / min and the 600℃ heat treatment is carried out for 2h at the flow rate of the nitrogen gas, after the heat treatment, the flow rate of the nitrogen gas is decreased to 0 L / min at a rate of 0.25 L / min and then the nitrogen gas source is closed, at the same time, after the heat treatment, the temperature is naturally decreased to room temperature 25℃, and finally the modified porous ceramic wave-transparent material is obtained.

[0096] Comparative Example 1

[0097] The surface of the quartz fiber reinforced composite material with a thickness of 10 mm and a porosity of 45% in Example 1 is subjected to airflow scouring to remove excess particles on the surface, and no other treatment is carried out subsequently, and the performance test is directly carried out.

[0098] Comparative Example 2

[0099] ① The surface of the quartz fiber reinforced composite material with a thickness of 10 mm and a porosity of 45% in Example 1 is subjected to airflow scouring to remove excess particles on the surface.

[0100] (2) The surface of the base material is impregnated and dried using polysilazane (ceramic yield 65%, viscosity 300 cP), and the impregnation and drying are repeated 8 times in sequence, the drying temperature is room temperature 25 DEG C, the time for each drying is 5 h, then the temperature is raised to 200 DEG C under nitrogen atmosphere, and the material is cured for 4 h, after the curing is completed, the temperature is lowered to room temperature 25 DEG C, finally, the temperature is raised to 600 DEG C at a rate of 5 DEG C / min from room temperature 25 DEG C, the material is heat treated at 600 DEG C for 2 h under nitrogen atmosphere with a flow rate of 12.5 L / min, after the heat treatment is completed, the nitrogen source is turned off, and the material is naturally cooled to room temperature 25 DEG C, and finally the modified porous ceramic wave-transparent material is obtained.

[0101] Comparative Example 3

[0102] Comparative Example 3 is basically the same as Example 1, except that in step (2), the boron nitride powder (average particle size 200 nm, purity ≥ 99%) and the boron oxide powder (average particle size 500 nm, purity ≥ 99%) are mixed uniformly in a mass ratio (denoted as mass ratio A) of 100:66 to form the base filler.

[0103] Comparative Example 4

[0104] Comparative Example 4 is basically the same as Example 1, except that in step (3), the base filler is added to the polysilazane (ceramic yield 65%, viscosity 300 cP) and mixed uniformly, then ground at a speed of 30 r / min for 5 min, and then filtered with a precision of 5 μm to form a composite impregnation solution, wherein the mass ratio (denoted as mass ratio B) of the polysilazane to the base filler is 100:15.

[0105] Comparative Example 5

[0106] Comparative Example 5 is basically the same as Example 1, except that in step (2), the boron nitride powder, the boron oxide powder and the surface modifier are mixed uniformly in a mass ratio (denoted as mass ratio A) of 100:200:10 to form the base filler.

[0107] The modified porous ceramic wave-transparent materials prepared in the examples are tested for performance, and the test results are shown in Table 1; the quartz fiber reinforced composite material in Comparative Example 1 and the modified porous ceramic wave-transparent materials prepared in Comparative Examples 2-5 are tested for performance, and the test results are shown in Table 2.

[0108]

[0109] Table 2

[0110] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Porosity of base material 45％ 45％ 45％ 45％ 45％ Polysilazane ceramic yield / 65％ 65％ 65％ 65％ Mass ratio A / / 100：66：0 100：66：10 100：200：10 Mass ratio B / / 100：15：0.1 100：15：0 100：15：0.1 Dipping and drying frequency (times) / 8 8 8 8 Linear ablation rate at 1400°C (mm / s) 0.210 0.093 0.041 0.045 0.026 Average wave permeability at 8-18 GHz 93％ 80％ 84％ 84％ 60％

[0111] In Table 2, the symbol " / " represents that the parameter does not exist; according to the results of Table 1 and Table 2, it can be seen that the embodiment 1 of the present application is a better example, the modified porous ceramic wave-transparent material prepared by selecting appropriate parameter indicators has better high-temperature resistance and ablation resistance and good wave-transparent performance; in comparison, reducing the impregnation times will reduce the high-temperature resistance and ablation resistance, thus the overall effect also has certain differences (embodiment 2); and increasing the impregnation times has little effect on the performance (embodiment 3), and will cause the cycle to be prolonged and the cost to be increased. The present application finds that reducing the proportion of the surface modifier will reduce the high-temperature resistance and ablation resistance by adjusting the mass ratio A, which may be caused by poor compatibility (embodiment 4); and increasing the proportion of the surface modifier will also reduce the effect to a certain extent, which may be caused by the low high-temperature resistance of the surface modifier after being excessive (embodiment 5); the present application finds that reducing the proportion of the defoaming agent will reduce the high-temperature resistance and ablation resistance by adjusting the mass ratio B, which may be caused by the low density caused by excessive bubbles (embodiment 6); and increasing the proportion of the defoaming agent will also reduce the effect to a certain extent, which may be caused by the fact that the composite impregnation liquid cannot be firmly attached to the base material after being excessive, thus affecting the performance of the ceramic wave-transparent material (embodiment 7); the modified porous ceramic wave-transparent material prepared in the more preferred embodiments 8-10 has better high-temperature resistance and ablation resistance and more excellent wave-transparent performance compared with the embodiment 1. It can be found from the comparative examples that for the quartz fiber reinforced composite material, using polysilazane impregnation alone has certain high-temperature resistance and ablation resistance (comparative example 2), and by adding the composite filler, the high-temperature resistance and ablation resistance are better; and by adding the surface modifier or the defoaming agent, the high-temperature resistance and ablation resistance are further improved (comparative example 3 and comparative example 4). In addition, regarding the amount of the filler, the amount of boron oxide cannot be excessive, otherwise the ablation resistance will be reduced and the wave-transparent rate will be low (comparative example 5). Therefore, the modified porous ceramic wave-transparent material prepared by the present application can better play the high-temperature resistance and ablation resistance and the wave-transparent performance.

[0112] The part not described in detail in the present application is the technology known to those skilled in the art.

[0113] Although the present application has been described in more detail above by way of example, it should be understood that those skilled in the art are capable of modifying the technical solutions of the present application without creative efforts, for example, by replacing the basic same or similar technical features, thus obtaining new technical solutions which are basically the same or similar, but the essence of these technical solutions does not deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should belong to the protection scope of the present application.

Claims

1. A method for preparing a modified porous ceramic-based microwave-transparent material, characterized in that, The preparation method includes the following steps: (1) Mix boron nitride powder, boron oxide powder and surface modifier evenly to obtain basic filler; (2) Add the basic filler and defoamer to polysiloxane and mix evenly, then grind and filter to obtain a composite impregnation solution; (3) The substrate material is impregnated and dried using the composite impregnation liquid and then cured to obtain a cured preform; (4) The solidified preform is subjected to heat treatment to obtain a modified porous ceramic-based microwave-transparent material.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the surface modifier to the boron nitride powder is (2~20):100; and / or The mass ratio of the surface modifier to the boron oxide powder is (3~30):

100.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the base filler to the polysiloxane is (5~30):100; and / or The mass ratio of the defoamer to the polysiloxane is (0.03~0.3):

100.

4. The preparation method according to claim 1, characterized in that: The surface modifier is one or more of the following: organosilicon resins, dopamine, and silane coupling agents; The defoamer is one or more of polyether-based defoamers, silicone-based defoamers, and polyether-modified silicone-based defoamers; and / or The ceramic yield of the polysiloxane is not less than 60%, and the room temperature viscosity of the polysiloxane is 50 cP to 500 cP. The grinding is performed manually or using grinding equipment, the grinding speed is 10 r / min to 100 r / min, and the grinding time is 1 min to 10 min; The filtration is performed manually or using a filtration facility, and the filtration accuracy is... .

5. The preparation method according to claim 1, characterized in that: The impregnation is atmospheric pressure impregnation, vacuum impregnation and / or pressure impregnation, and the impregnation time is 10 min to 60 min; The impregnation and drying process is repeated 3 to 15 times. The curing is carried out in a nitrogen atmosphere; and / or The heat treatment is carried out in a nitrogen atmosphere.

6. The preparation method according to claim 5, characterized in that: Ultrasonic treatment is also introduced during the curing process.

7. The preparation method according to claim 5, characterized in that: During the process of heating to the heat treatment temperature, the flow rate of nitrogen increases with the increase of temperature. The initial flow rate of nitrogen is 1~2 L / min, and the rate of increase of nitrogen flow rate is 0.1~0.2 L / min. When the heat treatment temperature is reached, the flow rate of nitrogen is 10~20 L / min, and heat treatment is carried out at this nitrogen flow rate.

8. The preparation method according to claim 1, characterized in that: The curing temperature is 160℃~230℃, and the curing time is 2h~10h; and / or The heat treatment temperature is 550℃~650℃, and the heat treatment time is 1h~5h.

9. The preparation method according to claim 1, characterized in that: The boron nitride powder and / or boron oxide powder are micron-sized, submicron-sized, or nano-sized powders; and / or The purity of the boron nitride powder and / or boron oxide powder is not less than 99%.

10. The preparation method according to claim 1, characterized in that: The substrate material is a porous ceramic-based wave-transparent material.

11. The preparation method according to claim 10, characterized in that: The porous ceramic-based wave-transmitting material is one or more of the following: quartz fiber reinforced composite material, mullite fiber reinforced composite material, and alumina fiber reinforced composite material.

12. The preparation method according to claim 10, characterized in that: The porous ceramic-based microwave-transparent material is one or more of quartz ceramic materials, mullite ceramic materials, and alumina ceramic materials.

13. The preparation method according to claim 10, characterized in that: The porosity of the porous ceramic-based microwave-transparent material is 30%~60%.

14. A modified porous ceramic-based microwave-transparent material, characterized in that: The porous ceramic-based microwave-transparent material is prepared by any one of claims 1 to 13.

15. The use of the porous ceramic-based wave-transparent material of claim 14 as a wave-transparent material for high-speed aircraft.

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