A heat-proof and stealth dual-functional coating material capable of being coated into a shape and a preparation method thereof

Abstract

This invention discloses a coatable, moldable dual-functional coating material for heat protection and stealth, and its preparation method. The coating material is formed from a SiC-based composite ceramic aerogel slurry, a perovskite / MAX phase composite ceramic absorber, and a high-temperature resistant binder. The composite ceramic aerogel slurry is composed of SiC micro / nano-scale aerogel powder, SiC nanowires, and a high-temperature resistant binder; the perovskite ceramic absorber is lanthanum strontium manganese oxide (La). 1‑x Sr x MnO3), lanthanum strontium iron oxide (La) 1‑ x Sr x FeO3), lanthanum strontium cobalt oxide (La) 1‑x Sr x The MAX phase ceramic absorber is Ti3SiC2, and it contains substances such as CoO3. The technology of this invention enables the rapid application of coating materials to the surface of equipment via brushing, enhancing high-temperature radar absorption stealth and thermal protection capabilities, and facilitating the preparation and efficient repair of high-temperature stealth coatings.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of stealth coating material preparation, and particularly relates to a heat-proof and stealth dual-functional coating material capable of being coated and formed and a preparation method thereof. BACKGROUND

[0002] The fierce competition between radar detection and counter-detection has become a hot topic. Since the stereoscopic reconnaissance strike capability of the early warning detection and defense interception system network is continuously improved, military aircraft urgently needs to have strong stealth performance to improve the survival and penetration capabilities. In addition, when the aircraft is flying at hypersonic speed, the shell part needs to withstand the high temperature generated by aerodynamic heating and the strong thermal shock and ablation damage caused thereby, and the efficient thermal insulation problem needs to be considered. At the same time, with the increase of flight Mach number, the shell surface temperature will increase significantly. Due to the low Curie temperature and the limitation of high-temperature soft magnetic performance of the traditional magnetic wave-absorbing material, the stealth performance will be greatly attenuated. Therefore, the integration technology of stealth and heat protection has become the key to the development and application of future hypersonic aircraft.

[0003] Ceramic-based materials have high melting point, high thermal stability, good ablation resistance, and thus are highly concerned in the field of thermal protection of hypersonic aircraft at home and abroad. However, most of the ceramic-based thermal protection coatings are prepared by methods such as thermal spraying and plasma spraying, which have harsh process conditions, long preparation period, high cost, and certain damage to the structure parts, and are not conducive to large-scale application. Since most of the ceramic-based thermal protection coatings have poor impedance matching with free space, they also do not have good electromagnetic wave-absorbing stealth performance. In addition, the current thermal spraying technology of stealth coating is relatively complex and inefficient. At the same time, due to long-term aerodynamic friction and external impact, the surface stealth coating needs to be repaired and maintained regularly to maintain the survival and penetration capabilities of the equipment for performing military tasks. Therefore, it is of great significance to develop a new type of high-temperature thermal protection / electromagnetic stealth integrated coating and preparation technology to realize the low-temperature, rapid and low-cost preparation of heat-proof / stealth coating. SUMMARY

[0004] The realization of lightweight, high-temperature stealth and thermal protection integrated coating and its efficient and low-cost coating preparation process has important value for improving the performance of equipment. Therefore, the present application provides a heat-proof and stealth dual-functional coating material capable of being coated and formed and a preparation method thereof, which can quickly coat the coating material on the surface of the equipment by brushing, improve the high-temperature wave-absorbing stealth and thermal protection capability, and facilitate the realization of high-temperature stealth coating preparation and efficient repair. In order to achieve the above application purposes, the present application discloses the following technical solutions.

[0005] Firstly, the application provides a heat-proof and stealth dual-functional coating material which can be coated and formed, and the coating material is formed by a SiC-based composite ceramic aerogel slurry, a perovskite / MAX phase composite ceramic absorber and a high-temperature-resistant binder.

[0006] Further, the perovskite / MAX phase mixed ceramic absorber is prepared by the following method:

[0007] (1) The lanthanum source, strontium source, manganese source or cobalt source or iron source and citric acid are sequentially added to water and stirred uniformly, and then the obtained mixed solution is heated and stirred to form a gel product.

[0008] (2) The gel product is dried and ground into powder, and the obtained powder product is annealed to obtain the perovskite ceramic absorber with the chemical formula of La 1-x Sr x MO3, and the x ranges from 0 to 0.5. The M can be manganese, cobalt, iron and the like, i.e., the perovskite ceramic absorber is lanthanum strontium manganese oxide (La 1-x Sr x MnO3), lanthanum strontium iron oxide (La 1-x Sr x FeO3), lanthanum strontium cobalt oxide (La 1-x Sr x CoO3) and the like.

[0009] (3) The perovskite ceramic absorber is mixed with the MAX phase ceramic absorber and then ball milled to obtain the perovskite / MAX phase composite ceramic absorber. The mass ratio of the perovskite ceramic absorber to the MAX phase ceramic absorber in the perovskite / MAX phase mixed ceramic absorber is 1:1-3:2, and the MAX phase ceramic absorber is Ti3SiC2.

[0010] Further, in step (1), the lanthanum source includes at least one of lanthanum nitrate, lanthanum sulfate and lanthanum chloride. The strontium source includes at least one of strontium nitrate, strontium sulfate and strontium chloride. The manganese source includes at least one of manganese nitrate, manganese sulfate and manganese chloride. The cobalt source includes at least one of cobalt nitrate, cobalt sulfate and cobalt chloride. The iron source includes at least one of iron nitrate, iron sulfate and iron chloride.

[0011] Further, in step (1), the heating temperature is 60°C.

[0012] Further, in step (2), the drying temperature is 150°C, and the drying time is 2.5-4 hours.

[0013] Further, in step (2), the annealing temperature is 600-800 DEG C, and the annealing time is 20-22 hours.

[0014] Further, in step (3), the ball milling time is 6-10 hours.

[0015] Further, the mass ratio of the SiC micro-nano aerogel powder and the SiC nanowire of the composite ceramic aerogel is 1:1-7:3, and then the composite ceramic aerogel is mixed with the high-temperature resistant binder at a mass ratio of 1:4-2:3.

[0016] Further, the mass ratio of the composite ceramic aerogel slurry and the perovskite / MAX phase mixed ceramic absorber is 1:4-3:7.

[0017] Further, the high-temperature resistant binder comprises at least one of water glass, copper oxide-phosphoric acid glue, etc.

[0018] Secondly, the application discloses a preparation method of the heat-proof and stealth dual-functional coating material which can be coated and formed, comprising the following steps: mixing the composite ceramic aerogel slurry and the perovskite / MAX phase composite ceramic absorber to form a uniform slurry, then coating the slurry on the surface of a metal base plate to form a coating, and naturally airing or heating and drying.

[0019] Further, when the thickness of the coating is not more than 2 mm, the natural airing time is 12-24 hours, or the heating and drying temperature is 40-300 DEG C and the time is 1-5 hours.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] Benefited from the complementary and coupling gain effect between the SiC micro-nano aerogel powder-SiC nanowire composite ceramic aerogel and the perovskite / MAX phase composite ceramic absorber, a lightweight high-temperature heat protection and high-temperature stealth integrated composite coating is obtained. The porous structure of the SiC-based composite ceramic aerogel is beneficial to the entry of electromagnetic waves into the interior of the composite material, and can effectively adjust the electromagnetic parameters of the composite material, improve the impedance matching between the material and the electromagnetic wave, and then increase the absorption of the composite material to the electromagnetic wave. In addition, the pores of different sizes generated in the electromagnetic wave absorbing material can produce multiple scattering and reflection of the incident electromagnetic wave, prolong the propagation path and increase the loss process. At the same time, the high-efficiency heat insulation of the ceramic aerogel material can help to reduce the temperature of the inner layer, so that the perovskite / MAX phase composite ceramic absorber in the inner layer can weaken the influence of the high-temperature environment and maintain better performance. Especially, the perovskite / MAX phase composite ceramic absorber prepared by the process of the application still has good chemical stability in the air atmosphere at 800-1200 DEG C environment, and has excellent high-temperature wave absorbing capacity. The SiC nanowire fiber is used to enhance the SiC micro-nano aerogel powder and the ceramic absorber, which can better provide mechanical properties and shape retention performance. At the same time, the perovskite / MAX phase composite ceramic absorber has light weight and low density, and the SiC-based composite ceramic aerogel has lower density, which provides a solution to the problem of reducing the mass of the overall composite wave absorbing material and providing lightweight high-temperature efficient wave absorbing stealth application for aircraft heat / stealth protection. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which form a part of the present description, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application.

[0023] Figure 1 The lanthanum-strontium-manganese-oxygen ceramic nanometer powder sample diagram prepared for the following example 1.

[0024] Figure 2 The heat and stealth dual-functional coating material sample diagram prepared for the following example 1.

[0025] Figure 3 The microwave absorption stealth effect test diagram of the heat and stealth dual-functional coating material of the following example 1.

[0026] Figure 4 The thermogravimetric analysis curve diagram of the heat and stealth dual-functional coating material of the following example 1.

[0027] Figure 5 The microwave absorption stealth effect test diagram of the heat and stealth dual-functional coating material of the following example 2.

[0028] Figure 6 The thermogravimetric analysis curve diagram of the heat and stealth dual-functional coating material of the following example 2.

[0029] Figure 7 Figure for microwave absorption stealth effect test of heat-proof and stealth dual-functional coating material of Example 3 below.

[0030] Figure 8 Figure for thermogravimetric analysis curve of heat-proof and stealth dual-functional coating material of Example 3 below. DETAILED DESCRIPTION

[0031] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. The present application is further illustrated by specific embodiments.

[0032] Example 1

[0033] A preparation method of a coatable and formable heat-proof and stealth dual-functional coating material, comprising the steps of:

[0034] 1. Preparation of lanthanum-strontium-manganese oxide ceramic wave absorber:

[0035] (1) Take lanthanum nitrate (La(NO3)3) 0.2 mol, manganese nitrate (Mn(NO3)2) 0.25 mol, strontium nitrate (Sr(NO3)2) 0.05 mol, and citric acid (C6H 10 O8) 0.5 mol, and add them into 1 L of water in sequence and stir until uniform. Then, continuously stir magnetically at 60°C to slowly evaporate the excess water, and obtain a gel.

[0036] (2) Grind the gel into powder after drying at 150°C for 3 hours, and then anneal at 600°C for 20 hours to obtain black lanthanum-strontium-manganese oxide ceramic nano-powder, as shown in the figure. Figure 1

[0037] 2. Preparation of composite ceramic aerogel slurry: Mix SiC nano-particles and SiC micro-nano level aerogel powder according to a mass ratio of 1:1, and then mix the obtained mixture with water glass according to a mass ratio of 1:4, stir to form uniform, and obtain the composite ceramic aerogel slurry, ready for use.

[0038] 3. Mix the ceramic nano-powder prepared in this embodiment with Ti3SiC2 according to a mass ratio of 1:1, and then mix by ball milling process for 10 hours to obtain perovskite / MAX phase composite ceramic absorber.

[0039] 4. Mix the composite ceramic aerogel slurry and the perovskite / MAX phase composite ceramic absorber prepared in this embodiment according to a mass ratio of 4:6, and then stir to be uniform, and obtain the coating material.

[0040] 5. Apply the coating material to the surface of a metal base plate by scraping method, and naturally cool and dry for 15 hours to obtain a heat-proof and stealth dual-functional coating material, as shown in the figure. Figure 2 ​The heat-proof and stealth dual-functional coating material shown.

[0041] Benefiting from the reinforcing effect of the SiC nanowire fibers, the coating material prepared in the embodiment can ensure better mechanical properties and shape retention properties. Meanwhile, benefiting from the porous structure of the SiC aerogel, the coating material prepared in the embodiment can ensure high-efficiency heat insulation effect. In addition, the SiC nanowire fiber reinforced SiC aerogel composite material has better high-temperature heat resistance. Since the lanthanum-strontium-manganese-oxygen / Ti3SiC2 composite ceramic absorber has better electromagnetic wave absorption stealth performance in a high-temperature environment, and the porous structure of the SiC-based composite ceramic aerogel is conducive to the entry of electromagnetic waves into the inside of the composite material, improving the impedance matching between the material and the electromagnetic waves, and thus increasing the absorption of the coating material prepared in the embodiment to the electromagnetic waves. As shown in the figure, the microwave absorption stealth effect of the coating material prepared in the embodiment is about 2 mm in a 900℃ high-temperature environment in a 2-18 GHz frequency band. Figure 3 As shown in the figure, the coating material prepared in the embodiment has better low reflectivity due to strong wave absorption, and the minimum reflectivity can reach -32.56 dB. The thermogravimetric analysis curve of the coating material prepared in the embodiment is as shown in the figure. Figure 4 Obviously, the composite material has good thermal stability within 1200℃. In addition, the lanthanum-strontium-manganese-oxygen / Ti3SiC2 composite ceramic absorber has light weight and low density, and the SiC-based composite ceramic aerogel has lower density, which is conducive to reducing the mass of the overall composite wave-absorbing coating material and providing a light-weight high-temperature-resistant high-efficiency wave-absorbing stealth coating for aircraft thermal / stealth protection.

[0042] Embodiment 2

[0043] A preparation method of a heat-proof and stealth dual-functional coating material that can be coated and formed, comprising the steps of:

[0044] 1. Preparation of lanthanum-strontium-cobalt-oxygen ceramic wave absorber:

[0045] (1) Take lanthanum nitrate (La(NO3)3) 0.2 mol, cobalt nitrate (Co(NO3)2) 0.25 mol, strontium nitrate (Sr(NO3)2) 0.05 mol, and citric acid (C6H 10 O8) 0.5 mol, and add them to 1L water in sequence and stir until uniform. Then, continuously magnetically stir at 60℃ to slowly evaporate the excess water, and obtain a gel.

[0046] (2) Grind the gel into powder after drying at 150℃ for 2.5 hours, and then anneal at 800℃ for 20 hours to obtain lanthanum-strontium-cobalt-oxygen ceramic nano powder.

[0047] 2. Preparation of composite ceramic aerogel slurry: SiC nanoparticles and SiC micro-nano aerogel powder are mixed in a mass ratio of 7:3, and the obtained mixture is mixed with water glass in a mass ratio of 2:3 to form a uniform mixture, thereby obtaining the composite ceramic aerogel slurry, which is ready for use.

[0048] 3. The perovskite / MAX phase composite ceramic absorber is obtained by mixing the ceramic nanopowder prepared in this example and Ti3SiC2 in a mass ratio of 3:2 and then ball milling for 6 hours.

[0049] 4. The coating material is obtained by mixing the composite ceramic aerogel slurry prepared in this example and the perovskite / MAX phase composite ceramic absorber in a mass ratio of 1:4 and then stirring uniformly.

[0050] 5. The coating material is applied to the surface of a metal base plate by the doctor blade method, and is naturally cooled and dried for 24 hours to obtain a heat-resistant and stealth dual-functional coating material.

[0051] Thanks to the reinforcing effect of SiC nanowire fibers, the coating material prepared in this example has good mechanical properties and shape retention performance. At the same time, thanks to the porous structure of SiC aerogel, the coating material prepared in this example has high efficient heat insulation effect. In addition, SiC nanofiber reinforced SiC aerogel composite material has good high temperature resistance. Since the lanthanum-strontium-cobalt oxide / Ti3SiC2 composite ceramic absorber has good electromagnetic wave absorption stealth performance in a high temperature environment, and the porous structure of the SiC-based composite ceramic aerogel is conducive to the entry of electromagnetic waves into the interior of the composite material, improving the impedance matching between the material and the electromagnetic waves, thereby increasing the absorption of the coating material prepared in this example to electromagnetic waves. As shown in Figure 5 , the coating material prepared in this example has good low reflectivity due to strong wave absorption, with the lowest reflectivity reaching -25.42 dB. The thermogravimetric analysis curve of the coating material prepared in this example is shown in Figure 6 , which shows that the composite material has good thermal stability at 1000°C. In addition, the lanthanum-strontium-cobalt oxide / Ti3SiC2 composite ceramic absorber has low density, and the SiC-based composite ceramic aerogel has lower density, which helps to reduce the mass of the overall composite wave-absorbing coating material and provide a lightweight high-temperature-resistant efficient wave-absorbing stealth coating for aircraft thermal / stealth protection.

[0052] Example 3

[0053] A method for preparing a heat-resistant and stealth dual-functional coating material that can be coated and formed, comprising the steps of:

[0054] 1. Preparation of lanthanum-strontium-iron oxide ceramic wave absorber:

[0055] (1) Take lanthanum nitrate (La(NO3)3) solution 0.2 mol, iron nitrate (Fe(NO3)2) solution 0.25 mol, strontium nitrate (Sr(NO3)2) solution 0.05 mol, citric acid (C6H 10 O8) 0.5 mol into 1L water in turn, stir evenly, then continue to evaporate the excess water at 60℃ under magnetic stirring, get the gel.

[0056] (2) The gel is dried at 150℃ for 4 hours, then ground into powder, then annealed at 700℃ for 22 hours to get lanthanum strontium ferrite nanometer powder.

[0057] 2, Preparation of composite ceramic aerogel slurry: SiC nanoparticles, SiC micro-nano aerogel powder are mixed according to the mass ratio of 2:1, then the mixture is mixed with copper oxide-phosphoric acid glue according to the mass ratio of 1:4 to form a uniform mixture, which is the composite ceramic aerogel slurry.

[0058] 3, The ceramic nanometer powder prepared in this embodiment is mixed with Ti3SiC2 according to the mass ratio of 1:1, and then ball milling is used to mix the mixture for 8 hours to obtain perovskite / MAX phase composite ceramic absorber.

[0059] 4, The composite ceramic aerogel slurry and perovskite / MAX phase composite ceramic absorber prepared in this embodiment are mixed according to the mass ratio of 3:7, and then stirred uniformly to obtain the coating material.

[0060] 5, The coating material is coated on the surface of the metal base plate by scraping method, and then naturally cooled and dried for 12 hours to obtain the heat-proof and stealth dual-functional coating material.

[0061] Thanks to the reinforcing effect of SiC nanowire fibers, the coating material prepared in this embodiment has good mechanical properties and shape retention performance. At the same time, thanks to the porous structure of SiC aerogel, the coating material prepared in this embodiment has high efficient heat insulation effect. In addition, SiC nanofiber reinforced SiC aerogel composite material has good high temperature resistance. Since the lanthanum strontium ferrite / Ti3SiC2 composite ceramic absorber has good electromagnetic wave absorption stealth performance in high temperature environment, and the porous structure of SiC-based composite ceramic aerogel is beneficial to the entry of electromagnetic waves into the composite material, improving the impedance matching between the material and the electromagnetic waves, thereby increasing the absorption of the coating material prepared in this embodiment to the electromagnetic waves. The microwave absorption stealth effect of the coating material prepared in this embodiment is about 1.5 mm in the frequency range of 2~18 GHz in a 500℃ high temperature environment as shown in the figure. Figure 7As shown, the low reflectivity is good due to strong wave absorption, and the minimum reflectivity can reach-29.36 dB. The thermogravimetric analysis curve of the coating material prepared in the embodiment is as shown in Figure 8 As shown, it is obvious that the composite material has good thermal stability within 1000℃. In addition, the lanthanum-strontium ferrite / Ti3SiC2 composite ceramic absorber has low density, and the SiC-based composite ceramic aerogel has lower density, which is beneficial to reduce the mass of the overall composite wave-absorbing coating material and provide a light-weight high-temperature-resistant high-efficiency wave-absorbing stealth coating for aircraft thermal / stealth protection.

[0062] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A dual functional coating material for heat protection and stealth, which can be coated into a shaped form, characterized in that, The coating material is formed by a SiC-based composite ceramic aerogel slurry and a perovskite / MAX phase composite ceramic absorber; the composite ceramic aerogel slurry is composed of SiC micro-nano aerogel powder, SiC nanowires and a high-temperature resistant binder; the high-temperature resistant binder includes at least one of water glass and copper oxide-phosphoric acid glue. The perovskite / MAX phase mixed ceramic absorber is prepared by the following method: (1) adding a lanthanum source, a strontium source, a manganese source or a cobalt source or an iron source and citric acid into water in sequence and stirring until uniform, and then heating and stirring the mixed solution to form a gel product; (2) The gelatinous product is dried and ground into powder, and the obtained powder is annealed to obtain the perovskite ceramic wave-absorbing agent of the formula La 1-x Sr x MO3, wherein x is in the range of 0≤x≤0.5, and M includes any one of manganese, cobalt and iron elements. (3) mixing the perovskite ceramic absorber and the MAX phase ceramic absorber and then ball milling to obtain the perovskite / MAX phase composite ceramic absorber; the mass ratio of the perovskite ceramic absorber to the MAX phase ceramic absorber in the perovskite / MAX phase mixed ceramic absorber is 1:1-3:2, and the MAX phase ceramic absorber is Ti3SiC2.

2. The coatable shaped dual function thermal and stealth coating material according to claim 1, wherein, In step (1), the lanthanum source includes at least one of lanthanum nitrate, lanthanum sulfate and lanthanum chloride.

3. The thermo- and stealth dual functional coating material according to claim 1, wherein, The strontium source includes at least one of strontium nitrate, strontium sulfate and strontium chloride.

4. The thermo- and stealth dual functional coating material according to claim 1, wherein, The manganese source includes at least one of manganese nitrate, manganese sulfate and manganese chloride.

5. The thermo- and stealth dual functional coating material according to claim 1, wherein, The cobalt source includes at least one of cobalt nitrate, cobalt sulfate and cobalt chloride.

6. The thermo- and stealth dual function coatable shaped coating material according to claim 1, wherein, The iron source includes at least one of iron nitrate, iron sulfate and iron chloride.

7. The thermo- and stealth dual function coatable shaped coating material according to claim 1, wherein, In step (1), the heating temperature is 60°C.

8. The thermo- and stealth dual function coatable shaped coating material according to claim 1, wherein, In step (2), the drying temperature is 150°C, and the drying time is 2.5-4 hours.

9. The thermo- and stealth dual function coatable shaped coating material according to claim 1, wherein In step (2), the annealing temperature is 600-800°C, and the annealing time is 20-22 hours.

10. The coatable shaped dual function thermal and stealth coating material of claim 1, wherein, In step (3), the ball milling time is 6-10 hours.

11. The coatable shaped dual function thermal and stealth coating material according to any one of claims 1-10, wherein, The mass ratio of the SiC micro-nano aerogel powder to the SiC nanowires in the composite ceramic aerogel is 1:1-7:3, and then the composite ceramic aerogel is mixed with the high-temperature resistant binder at a mass ratio of 1:4-2:

3.

12. The coatable shaped dual function thermal and stealth coating material according to any one of claims 1-10, wherein, The mass ratio of the composite ceramic aerogel slurry to the perovskite / MAX phase mixed ceramic absorber is 1:4-3:

7.

13. A process for the preparation of the coatable shaped dual function thermal and stealth coating material according to any one of claims 1 to 10, characterized in that, The method includes the following steps: mixing the composite ceramic aerogel slurry and the perovskite / MAX phase composite ceramic absorber to form a uniform slurry, and then applying the slurry to the surface of a metal base plate to form a coating, and then naturally air-drying or heating and drying.

14. The method of claim 13, wherein the method of preparing the coatable shaped dual function thermal and stealth coating material is characterized by, When the thickness of the coating is not more than 2 mm, the natural air-drying time is 12-24 hours, or the heating and drying temperature is 40-300°C, and the time is 1-5 hours.

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