High-temperature environment barrier / thermal barrier / electromagnetic shielding multifunctional composite coating and preparation method thereof

Abstract

The invention provides a high-temperature environmental barrier / thermal barrier / electromagnetic shielding multifunctional composite coating and a preparation method thereof.The multifunctional composite coating comprises a bonding layer, a Yb2Si2O7 environmental barrier layer, an electromagnetic shielding layer and an yttria-stabilized zirconia thermal barrier layer which are sequentially arranged from the surface of a composite material substrate to the outside; wherein the electromagnetic shielding layer is formed by screen-printing high-temperature-resistant electromagnetic shielding slurry on the surface of the Yb2Si2O7 environmental barrier layer, and the high-temperature-resistant electromagnetic shielding slurry comprises a conductive filler, modified glass powder and an organic carrier. The multifunctional composite coating in the scheme has excellent high-temperature oxidation resistance, water vapor corrosion resistance, low heat conductivity and high-temperature electromagnetic shielding effectiveness on the whole, and can stably work for a long time in an air environment of 1200 DEG C; the method is particularly suitable for reliable protection of hypersonic aircrafts, high-temperature precision equipment and measurement and control systems in an extreme heat-force-electricity multi-field coupling environment.

Description

Technical Field

[0001] This invention relates to the field of high-temperature protection and multifunctional composite coating materials, and particularly to a high-temperature environment barrier / thermal barrier / electromagnetic shielding multifunctional composite coating and its preparation method. Background Technology

[0002] With the accelerated development of aerospace technology towards hypersonic and extreme thermal environments, high-temperature ceramic composite materials have become key materials for hot-end components of aircraft and high-temperature measurement and control equipment. However, existing high-temperature ceramic composite materials face significant risks of environmental degradation and performance decline under multiple coupled loads such as high-temperature humid oxygen, strong heat flux, and complex electromagnetic environments. For example, in humid oxygen or water vapor environments exceeding 1200°C, glassy oxides easily form on their surfaces, leading to surface erosion, interface degradation, and even mechanical property deterioration. Strong temperature gradients under high heat flux density conditions also exacerbate the risk of surface microcrack propagation and interlayer delamination. Furthermore, in complex electromagnetic environments, high-temperature sensitive equipment and measurement and control systems are susceptible to electromagnetic interference or radiation damage. Therefore, the development of integrated composite coatings that simultaneously possess thermal barrier, environmental barrier, and electromagnetic shielding functions has become an urgent need.

[0003] However, existing coatings on composite material surfaces have relatively limited functions, primarily focusing on thermal insulation and oxidation protection, lacking effective electromagnetic shielding capabilities. This fails to meet the stringent requirements of advanced equipment for multifunctional material integration in complex electromagnetic environments. Furthermore, while conventional metal or carbon-based electromagnetic shielding coatings possess some shielding effectiveness, they are prone to oxidation, melting, or structural agglomeration in high-temperature environments, leading to a sharp decline in conductivity and stability, making it difficult to maintain reliable performance under prolonged high-temperature service conditions. In addition, existing coating systems often suffer from insufficient structural compatibility. Mismatches in thermal expansion coefficients, bonding strength, and interfacial reactions between different functional layers can easily cause interlayer delamination and microcrack propagation, hindering the systematic integration and synergy of thermal insulation, protection, and electromagnetic shielding performance.

[0004] Therefore, there is an urgent need to provide a multifunctional composite coating for high-temperature environment barrier / thermal barrier / electromagnetic shielding and its preparation method. Summary of the Invention

[0005] This invention provides a multifunctional composite coating for high-temperature environment barrier / thermal barrier / electromagnetic shielding and its preparation method, which can solve the problem that existing composite material coatings are difficult to achieve systematic integration and synergy of heat insulation, protection and electromagnetic shielding performance.

[0006] In a first aspect, the present invention provides a multifunctional composite coating for high-temperature environmental barrier / thermal barrier / electromagnetic shielding. Extending outward from the surface of a composite material matrix, the multifunctional composite coating comprises, sequentially arranged, an adhesive layer, a Yb₂Si₂O₇ environmental barrier layer, an electromagnetic shielding layer, and a yttrium oxide-stabilized zirconium oxide thermal barrier layer; wherein... The electromagnetic shielding layer is formed by screen printing a high-temperature resistant electromagnetic shielding paste onto the surface of the Yb2Si2O7 environmental barrier layer. The high-temperature resistant electromagnetic shielding paste contains conductive fillers, modified glass powder, and an organic carrier.

[0007] Preferably, the adhesive layer is a Si adhesive layer, an Al2O3 adhesive layer, or a 3Al2O3·2SiO2 adhesive layer.

[0008] Preferably, the thickness of the adhesive layer is 30~50μm.

[0009] Preferably, the thickness of the Yb2Si2O7 environmental barrier layer is no greater than 200 μm.

[0010] Preferably, the porosity of the yttrium oxide-stabilized zirconia thermal barrier layer is 5-20%, and the thickness is 0.8-2 mm.

[0011] Preferably, the thickness of the electromagnetic shielding layer is 10~50μm.

[0012] Preferably, the preparation method of the high-temperature resistant electromagnetic shielding paste is as follows: (11) Terpineol, butyl carbitol, tributyl citrate, ethyl cellulose and dispersant are mixed to obtain an organic carrier; wherein the dispersant is Span-85; (12) The conductive filler and modified glass powder are added to the organic carrier and mixed evenly, and then ground and degassed to obtain the high temperature electromagnetic shielding slurry; the conductive filler is preferably at least one of Ag, Pd, Pt, ITO or Au; the modified glass powder is preferably aluminoborosilicate glass powder.

[0013] Preferably, in step (11), the contents of each component in the organic carrier by mass percentage are as follows: terpineol 50-70%, butyl carbitol 15-25%, tributyl citrate 15-25%, dispersant 1-5%, ethyl cellulose 2-5%.

[0014] More preferably, in step (12), the aluminoborosilicate glass powder contains the following components by mass percentage: SiO2 60-75%, Al2O3 5-15%, B2O3 5-12%, Na2O 5-10%, ZnO 2-8%.

[0015] Preferably, in step (12), the mass ratio of conductive filler, modified glass powder and organic carrier is (15~45):(15~45):(40~60).

[0016] Secondly, embodiments of the present invention also provide a method for preparing the high-temperature environment barrier / thermal barrier / electromagnetic shielding multifunctional composite coating as described in any of the first aspects above, the preparation method comprising the following steps: (1) An adhesive layer is prepared on the surface of the composite matrix by spraying process, and then an atmospheric plasma spraying process is used to prepare a Yb2Si2O7 environmental barrier layer on the surface of the adhesive layer; (2) The high-temperature resistant electromagnetic shielding paste is printed onto the surface of the Yb2Si2O7 environmental barrier layer using screen printing technology, and the electromagnetic shielding layer is obtained after drying and sintering. (3) After the electromagnetic shielding layer is sandblasted, an atmospheric plasma spraying process is used to prepare a yttrium-stabilized zirconia thermal barrier layer on the surface of the electromagnetic shielding layer, thereby obtaining the high-temperature environment barrier / thermal barrier / electromagnetic shielding multifunctional composite coating.

[0017] Preferably, in step (2), the drying temperature is 100~200℃ and the heat preservation time is 30~60min.

[0018] Preferably, in step (2), the sintering temperature is 750~1000℃ and the holding time is 10~20min.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects: This invention employs a functionally graded structure design, with an adhesive layer, a Yb₂Si₂O₇ environmental barrier layer, an electromagnetic shielding layer, and a yttrium-stabilized zirconia (YSZ) thermal barrier layer sequentially arranged from the matrix outwards. The synergistic effect of these layers achieves integrated optimization and compatibility of environmental protection, thermal protection, and electromagnetic shielding performance. The inner Yb₂Si₂O₇ environmental barrier layer effectively blocks water vapor and oxygen corrosion, providing antioxidant protection for the composite matrix. The electromagnetic shielding layer utilizes a specially formulated high-temperature resistant slurry composed of conductive fillers, modified glass powder, and an organic carrier. The material, through screen printing, is tightly bonded to the environmental barrier layer. At high temperatures, it not only forms a stable and continuous conductive network, achieving efficient and durable electromagnetic shielding in the 4-18GHz frequency band, but its coefficient of thermal expansion after sintering is also similar to that of the environmental and thermal barrier layers. This allows for a gradient transition between the two layers, effectively mitigating stress concentration caused by thermal mismatch and inhibiting interlayer delamination and microcrack propagation. The outermost YSZ thermal barrier layer provides good thermal insulation, protecting the inner structure from aerodynamic erosion and thermal shock. Thus, this multifunctional composite coating possesses excellent resistance to high-temperature oxidation, water vapor corrosion, low thermal conductivity, and high-temperature electromagnetic shielding performance. It can operate stably for extended periods in an air environment at 1200℃, making it particularly suitable for reliable protection of hypersonic vehicles, high-temperature precision equipment, and telemetry and control systems in extreme thermo-mechanical-electric multi-field coupling environments. Attached Figure Description

[0020] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is an electromagnetic shielding effectiveness diagram of a high-temperature environment barrier / thermal barrier / electromagnetic shielding multifunctional composite coating provided in Embodiment 1 of the present invention in the frequency range of 4-18 GHz; in the figure, the horizontal axis is the frequency of electromagnetic waves, and the vertical axis is the total value of electromagnetic shielding effectiveness; Figure 2 This is an electromagnetic shielding effectiveness diagram of a high-temperature environment barrier / thermal barrier / electromagnetic shielding multifunctional composite coating provided in Embodiment 2 of the present invention in the frequency range of 4-18 GHz; in the figure, the horizontal axis is the frequency of electromagnetic waves, and the vertical axis is the total value of electromagnetic shielding effectiveness. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] As mentioned above, in the prior art, the coating on the surface of composite materials is often protected by thermal barrier coatings or environmental barrier coatings. Among them, thermal barrier coatings usually use yttrium-stabilized zirconia (YSZ) as the ceramic surface material, which is prepared by plasma spraying or electron beam physical vapor deposition. Its low thermal conductivity can effectively reduce the temperature of the substrate. For example, Chinese patent CN119707488A discloses a low thermal conductivity and sintering-resistant thermal barrier coating material, its preparation method and application. It achieves a thermal conductivity of less than 0.7 W / (m·k) by doping rare earth oxides in ZrO2, and has better thermal stability than YSZ. Furthermore, to improve the service reliability of SiC substrates in high-temperature and humid oxygen environments, environmental barrier coating systems represented by rare-earth silicates are often used, among which Yb₂Si₂O₇ is widely considered one of the most effective environmental barrier materials. For example, Chinese patent CN119707531B discloses an Al₂O₃-modified Yb₂Si₂O₇ material for surface environmental barrier coatings, its preparation method, and its application. By using Al₂O₃ to modify Yb₂Si₂O₇, its density and high-temperature corrosion resistance are improved, effectively enhancing the environmental protection performance of the coating. However, the aforementioned thermal barrier coatings and environmental barrier coatings mainly focus on heat insulation and oxidation resistance, with relatively simple functions, and all lack electromagnetic shielding capabilities.

[0024] To address the aforementioned problems, embodiments of the present invention provide a multifunctional composite coating for high-temperature environmental barrier / thermal barrier / electromagnetic shielding. Extending outwards from the surface of the composite material matrix, the multifunctional composite coating comprises, sequentially arranged, an adhesive layer, a Yb₂Si₂O₇ environmental barrier layer, an electromagnetic shielding layer, and a yttrium oxide-stabilized zirconium oxide thermal barrier layer; wherein... The electromagnetic shielding layer is formed by screen printing a high-temperature resistant electromagnetic shielding paste onto the surface of the Yb2Si2O7 environmental barrier layer. The high-temperature resistant electromagnetic shielding paste contains conductive fillers, modified glass powder, and an organic carrier.

[0025] In this embodiment of the invention, a functionally graded structure design is adopted, with an adhesive layer, a Yb₂Si₂O₇ environmental barrier layer, an electromagnetic shielding layer, and a yttrium-stabilized zirconia (YSZ) thermal barrier layer sequentially arranged from the matrix outwards. The synergistic effect between these layers achieves integrated optimization and compatibility of environmental protection, thermal protection, and electromagnetic shielding performance. The inner Yb₂Si₂O₇ environmental barrier layer effectively blocks water vapor and oxygen corrosion, providing antioxidant protection for the composite matrix. The electromagnetic shielding layer uses a specially formulated high-temperature resistant material composed of conductive fillers, modified glass powder, and an organic carrier. The paste, through screen printing, is tightly bonded to the environmental barrier layer. At high temperatures, it not only forms a stable and continuous conductive network, achieving efficient and durable electromagnetic shielding within the 4-18 GHz frequency band, but its coefficient of thermal expansion after sintering is also similar to that of the environmental and thermal barrier layers. This allows for a gradient transition between the two layers, effectively mitigating stress concentration caused by thermal mismatch and inhibiting interlayer delamination and microcrack propagation. The outermost YSZ thermal barrier layer provides good thermal insulation, protecting the inner structure from aerodynamic erosion and thermal shock. Thus, this multifunctional composite coating possesses excellent resistance to high-temperature oxidation, water vapor corrosion, low thermal conductivity, and high-temperature electromagnetic shielding performance. It can operate stably for extended periods in an air environment at 1200℃, making it particularly suitable for reliable protection of hypersonic vehicles, high-temperature precision equipment, and telemetry and control systems in extreme thermo-mechanical-electric multi-field coupling environments.

[0026] According to some preferred embodiments, the adhesive layer is a Si adhesive layer, an Al2O3 adhesive layer, or a 3Al2O3·2SiO2 adhesive layer; the thickness of the adhesive layer is 30~50μm (for example, it can be 30μm, 40μm or 50μm).

[0027] In this embodiment of the invention, by setting an adhesive layer of appropriate thickness on the surface of the composite matrix, a stable and reliable bond between the environmental barrier layer and the composite matrix can be ensured. If the thickness of the adhesive layer is too large, it is easy to cause a mismatch in the coefficient of thermal expansion, weakening the interfacial bonding strength between the environmental barrier layer and the composite matrix, and even inducing early coating failure. At the same time, the type of adhesive layer can be adapted to the type of composite matrix, which is beneficial to achieving better chemical compatibility and bonding effect. Thus, through the synergistic design of the thickness and material type, a durable and firm bond between the environmental barrier layer and the matrix can be achieved.

[0028] According to some preferred embodiments, the thickness of the Yb2Si2O7 environmental barrier layer is no greater than 200 μm (for example, it can be 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm or 200 μm).

[0029] According to some preferred embodiments, the porosity of the yttrium oxide stabilized zirconia thermal barrier layer is 5 to 20% (e.g., 5%, 10%, 15% or 20%), and the thickness is 0.8 to 2 mm (e.g., 0.8 mm, 1.0 mm, 1.5 mm or 2 mm).

[0030] According to some preferred embodiments, the thickness of the electromagnetic shielding layer is 10~50μm (for example, it can be 10μm, 20μm, 30μm, 40μm or 50μm).

[0031] In this embodiment of the invention, by spraying a Yb2Si2O7 environmental barrier layer of a certain thickness onto the surface of the adhesive layer, a dense protective barrier can be formed on the surface of the composite matrix, effectively blocking the penetration of water vapor and oxygen, and providing reliable anti-oxidation and corrosion protection for the composite matrix. By controlling the thickness of the environmental barrier layer, it is beneficial to achieve long-term environmental protection. If the thickness of the environmental barrier layer is too high, it will not only be difficult to further improve the environmental protection performance, but will also cause the coating to crack, thus reducing its environmental protection performance.

[0032] Meanwhile, a suitable thickness of yttrium-stabilized zirconia (YSZ) thermal barrier layer and electromagnetic shielding layer is beneficial to achieve high-temperature thermal insulation and electromagnetic shielding functions synergistically while ensuring good interfacial bonding performance of the coating. If the thickness of the YSZ thermal barrier layer is too high, crack propagation is easily triggered during thermal cycling, which will reduce the thermal protection performance. In addition, if the thickness of the electromagnetic shielding layer is too large, it will form a weak interface, which will reduce the interfacial bonding performance between the electromagnetic shielding layer and the adjacent layer.

[0033] According to some preferred embodiments, the preparation method of the high-temperature resistant electromagnetic shielding paste is as follows: (11) Terpineol, butyl carbitol, tributyl citrate, ethyl cellulose and dispersant are mixed to obtain an organic carrier; wherein the dispersant is Span-85; (12) The conductive filler and modified glass powder are added to the organic carrier and mixed evenly, and then ground and degassed to obtain the high temperature electromagnetic shielding slurry; the conductive filler is preferably at least one of Ag, Pd, Pt, ITO or Au; the modified glass powder is preferably aluminoborosilicate glass powder.

[0034] According to some preferred embodiments, in step (11), the contents of each component in the organic carrier by mass percentage are as follows: terpineol 50-70% (e.g., 50%, 55%, 60%, 65% or 70%), butyl carbitol 15-25% (e.g., 15%, 18%, 20%, 22% or 25%), tributyl citrate 15-25% (e.g., 15%, 18%, 20%, 22% or 25%), dispersant 1-5% (e.g., 1%, 2%, 3%, 4% or 5%), and ethyl cellulose 2-5% (e.g., 2%, 3%, 4% or 5%).

[0035] In this embodiment of the invention, by synergistically designing the components and proportions in the organic carrier, the integrity of the high-temperature structure of the electromagnetic shielding layer can be further guaranteed while taking into account the adaptability to the printing process. By rationally controlling the proportions of each component, not only can the high-temperature resistant electromagnetic shielding paste have a suitable viscosity, thus matching the requirements of the screen printing process and ensuring the uniformity of the printing process, but also, since the ignition points of the components in the organic carrier are different, gradient glue removal can be achieved in the subsequent sintering process. This can effectively avoid the problem of internal pores or cracks in the coating caused by the concentrated release of a large amount of gas in a short period of time, thereby ensuring that the electromagnetic shielding layer has good density and long-term stability after high-temperature sintering.

[0036] It should be noted that in the embodiments of the present invention, the particle size of the conductive filler is 0.1~5µm, and the average particle size of the glass powder is 2000 mesh.

[0037] According to some preferred embodiments, in step (12), the aluminoborosilicate glass powder comprises the following components by mass percentage: SiO2 60-75% (e.g., 60%, 62%, 65%, 70% or 75%), Al2O3 5-15% (e.g., 5%, 8%, 10%, 12% or 15%), B2O3 5-12% (e.g., 5%, 6%, 7%, 8%, 9%, 10%, 11% or 12%), Na2O 5-10% (e.g., 5%, 6%, 7%, 8%, 9% or 10%), and ZnO 2-8% (e.g., 2%, 3%, 4%, 5%, 6%, 7% or 8%).

[0038] Unlike traditional glass powder compositions, in this embodiment of the invention, the glass powder composition is optimized, with SiO2 and Al2O3 as the main components. This adjusts the sintering temperature and high-temperature viscosity of the glass phase. A small amount of B2O3, ZnO, and Na2O are added as fluxes to lower the melting temperature and improve fluidity and spreadability. The glass powder with the above-mentioned composition can be controlled to melt during sintering, thereby bonding the conductive fillers together to form a continuous and stable three-dimensional conductive network. At the same time, it promotes the overall densification of the coating and forms a strong chemical bond with adjacent layers. Furthermore, by precisely controlling the content of each component, not only can the thermal expansion coefficient of the electromagnetic shielding layer be well matched with that of the environmental barrier layer and the thermal barrier layer, but sintering can also be completed at a suitable temperature. This ensures the conductivity and structural stability of the electromagnetic shielding layer while improving its compatibility with the overall coating.

[0039] According to some preferred embodiments, in step (12), the mass ratio of conductive filler, modified glass powder and organic carrier is (15~45):(15~45):(40~60) (for example, it can be 15:15:40, 15:15:50, 15:15:60, 20:15:40, 20:20:50, 20:30:60, 30:20:40, 30:30:50, 30:45:60, 40:40:40, 40:40:60 or 45:45:60).

[0040] In this embodiment of the invention, by synergistically controlling the proportions of conductive filler, modified glass powder, and organic carrier in the high-temperature electromagnetic shielding slurry, a good overall performance of the electromagnetic shielding layer can be ensured. By adjusting the ratio of conductive filler to glass powder, the coefficient of thermal expansion of the electromagnetic shielding layer can be made similar to that of the environmental barrier layer and the thermal barrier layer, thereby effectively suppressing coating interface peeling or cracking caused by thermal mismatch. If the glass powder content is too low, it cannot fully encapsulate and bond the conductive filler, making it difficult to form a continuous and complete conductive path after thermal sintering, thus reducing the electromagnetic shielding performance. If the glass powder content is too high, the conductive filler content is relatively low, and the glass powder will isolate the contact between conductive particles, similarly hindering the connectivity of the conductive network and reducing the electromagnetic shielding performance. The content of organic carrier directly affects the printability of the slurry. If the organic carrier content is too high, although it is beneficial to the printing uniformity, it will generate a large number of pores or cracks during the sintering process due to excessive or rapid volatile matter, thereby destroying the integrity of the coating and affecting the close contact between the conductive filler and the glass powder.

[0041] In summary, by synergistically controlling the proportions of the three components, the glass phase can bond conductive fillers and fully fill the pores during sintering, forming a stable and continuous conductive network. At the same time, it can form a good interface bond with adjacent layers, thereby ensuring high-frequency electromagnetic shielding performance (in the range of 4-18 GHz) while endowing the coating with excellent thermal stability and long-term compatibility with the interface of multilayer coatings.

[0042] This invention also provides a method for preparing a multifunctional composite coating for high-temperature environment barrier / thermal barrier / electromagnetic shielding as described in any of the above embodiments, the method comprising the following steps: (1) An adhesive layer is prepared on the surface of the composite matrix by spraying process, and then an atmospheric plasma spraying process is used to prepare a Yb2Si2O7 environmental barrier layer on the surface of the adhesive layer; (2) The high-temperature resistant electromagnetic shielding paste is printed onto the surface of the Yb2Si2O7 environmental barrier layer using screen printing technology, and the electromagnetic shielding layer is obtained after drying and sintering. (3) After the electromagnetic shielding layer is sandblasted, an atmospheric plasma spraying process is used to prepare a yttrium-stabilized zirconia thermal barrier layer on the surface of the electromagnetic shielding layer, thereby obtaining the high-temperature environment barrier / thermal barrier / electromagnetic shielding multifunctional composite coating.

[0043] According to some preferred embodiments, in step (2), the drying temperature is 100~200℃ (for example, it can be 100℃, 120℃, 150℃, 180℃ or 200℃), and the holding time is 30~60min (for example, it can be 30min, 40min, 50min or 60min); the sintering temperature is 750~1000℃ (for example, it can be 750℃, 800℃, 850℃, 900℃, 950℃ or 1000℃), and the holding time is 10~20min (for example, it can be 10min, 15min or 20min).

[0044] In this embodiment of the invention, an adhesive layer and a Yb2Si2O7 environmental barrier layer are first formed on the substrate surface by plasma spraying. Then, a high-temperature resistant shielding paste is coated onto the surface of the environmental barrier layer by screen printing and dried and sintered to form an electromagnetic shielding layer. Finally, a YSZ thermal barrier layer is sprayed onto the surface of the electromagnetic shielding layer, thereby constructing a complete multifunctional gradient coating system that achieves multifunctional compatibility of high temperature resistance, low thermal conductivity, atmosphere protection, and electromagnetic shielding.

[0045] It should be noted that in the embodiments of the present invention, the plasma spraying process and the screen printing process are existing technologies. The process parameters can be selected according to actual needs during the preparation of the corresponding coating, which will not be elaborated here.

[0046] In summary, the high-temperature environment barrier / thermal barrier / electromagnetic shielding multifunctional composite coating prepared in the embodiments of the present invention is particularly suitable for key structural components of aircraft engines, reentry vehicles, hypersonic vehicles and other vehicles that are subjected to high heat flux and strong electromagnetic loads, as well as high-temperature precision equipment and functional components that need to operate stably for a long time under harsh temperature and atmosphere conditions. It can meet the integrated requirements for high-temperature insulation, atmosphere protection and electromagnetic shielding performance.

[0047] To more clearly illustrate the technical solution and advantages of the present invention, the following detailed description of a high-temperature environment barrier / thermal barrier / electromagnetic shielding multifunctional composite coating and its preparation method is provided through several embodiments.

[0048] Example 1: (1) Plasma spraying process is used on SiC f A bonding layer (a Si bonding layer with a thickness of 50 μm) was prepared on the surface of the SiC composite matrix, and then a Yb2Si2O7 environmental barrier layer with a thickness of 100 μm was prepared on the surface of the bonding layer by atmospheric plasma spraying. Preparation of high-temperature resistant electromagnetic shielding paste: (11) By mass percentage, 8% ethyl cellulose and 2% dispersant (Span-85) were added to 60% terpineol, 15% butyl carbitol and 15% tributyl citrate and stirred until homogeneous to obtain an organic carrier. (12) The conductive filler (Ag, Pt and ITO in a mass ratio of 1:1:1) and modified glass powder are added to the organic carrier and stirred and mixed. After grinding and degassing, a high-temperature electromagnetic shielding slurry is obtained. The modified glass powder contains 70% SiO2, 10% Al2O3, 10% B2O3, 7% Na2O, and 3% ZnO by mass percentage. The mass ratio of conductive filler, modified glass powder and organic carrier is 35:15:50. (2) Using screen printing technology, the high temperature resistant electromagnetic shielding paste is printed on the surface of Yb2Si2O7 environmental barrier layer, and then placed in an oven at 150℃ to dry for 1 hour. The dried coating is then placed in a muffle furnace and sintered at 1000℃ for 10 minutes. After cooling in the furnace, an electromagnetic shielding layer with a thickness of 30μm is obtained. (3) After the electromagnetic shielding layer is sandblasted, an atmospheric plasma spraying process is used to prepare a yttrium-stabilized zirconia thermal barrier layer with a porosity of 8% and a thickness of 1.5 mm on the surface of the electromagnetic shielding layer, thus obtaining a high-temperature environment barrier / thermal barrier / electromagnetic shielding multifunctional composite coating.

[0049] Example 2: (1) Plasma spraying process is used on Al2O 3fAn adhesive layer (50 μm thick Al2O3 adhesive layer) was prepared on the surface of the Al2O3 composite matrix, and then an atmospheric plasma spraying process was used to prepare a 150 μm thick Yb2Si2O7 environmental barrier layer on the surface of the adhesive layer. Preparation of high-temperature resistant electromagnetic shielding paste: (11) By mass percentage, 8% ethyl cellulose and 2% dispersant (Span-85) were added to 50% terpineol, 20% butyl carbitol and 20% tributyl citrate and stirred until homogeneous to obtain an organic carrier. (12) The conductive filler (Pd and Pt in a mass ratio of 1:1) and modified glass powder are added to the organic carrier and stirred and mixed. After grinding and degassing, a high-temperature electromagnetic shielding slurry is obtained. The modified glass powder contains 60% SiO2, 20% Al2O3, 10% B2O3, 7% Na2O, and 3% ZnO by mass percentage. The mass ratio of conductive filler, modified glass powder and organic carrier is 25:25:50. (2) Using screen printing technology, the high temperature resistant electromagnetic shielding paste is printed on the surface of Yb2Si2O7 environmental barrier layer, and then placed in an oven at 150℃ to dry for 1 hour. The dried coating is then placed in a muffle furnace and sintered at 800℃ for 20 minutes. After cooling in the furnace, an electromagnetic shielding layer with a thickness of 30μm is obtained. (3) After the electromagnetic shielding layer is sandblasted, an atmospheric plasma spraying process is used to prepare a yttrium-stabilized zirconia thermal barrier layer with a porosity of 8% and a thickness of 0.9 mm on the surface of the electromagnetic shielding layer, thus obtaining a high-temperature environment barrier / thermal barrier / electromagnetic shielding multifunctional composite coating.

[0050] The performance of the high-temperature environment barrier / thermal barrier / electromagnetic shielding multifunctional composite coating samples provided in the examples and comparative examples was tested, and the test results are shown in Table 1 below: Standard for thermal conductivity testing: GB / T 22588-2008 Flash method for measuring thermal diffusivity or thermal conductivity; Electromagnetic shielding parameter testing standard: GB / T 35679-2017 Method for measuring electromagnetic parameters of waveguide devices used in microwave bands for solid materials.

[0051] Table 1 Combining Table 1 and Figure 1 and Figure 2 It can be seen that the high-temperature environment barrier / thermal barrier / electromagnetic shielding multifunctional composite coating prepared in the embodiments of the present invention has excellent thermal insulation performance, electromagnetic shielding performance and atmosphere protection performance.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multifunctional composite coating for high-temperature environment barrier / thermal barrier / electromagnetic shielding, characterized in that, From the surface of the composite matrix outwards, the multifunctional composite coating includes, sequentially arranged, an adhesive layer, a Yb₂Si₂O₇ environmental barrier layer, an electromagnetic shielding layer, and a yttrium oxide-stabilized zirconium oxide thermal barrier layer; wherein, The electromagnetic shielding layer is formed by screen printing a high-temperature resistant electromagnetic shielding paste onto the surface of the Yb2Si2O7 environmental barrier layer. The high-temperature resistant electromagnetic shielding paste contains conductive fillers, modified glass powder, and an organic carrier.

2. The multifunctional composite coating according to claim 1, characterized in that, The adhesive layer is a Si adhesive layer, an Al2O3 adhesive layer, or a 3Al2O3·2SiO2 adhesive layer; and / or The thickness of the adhesive layer is 30~50μm.

3. The multifunctional composite coating according to claim 1, characterized in that, The thickness of the Yb2Si2O7 environmental barrier layer is no greater than 200 μm.

4. The multifunctional composite coating according to claim 1, characterized in that, The porosity of the yttrium oxide-stabilized zirconia thermal barrier layer is 5-20%, and the thickness is 0.8-2 mm.

5. The multifunctional composite coating according to claim 1, characterized in that, The thickness of the electromagnetic shielding layer is 10~50μm.

6. The multifunctional composite coating according to claim 1, characterized in that, The preparation method of the high-temperature resistant electromagnetic shielding paste is as follows: (11) Terpineol, butyl carbitol, tributyl citrate, ethyl cellulose and dispersant are mixed to obtain an organic carrier; wherein the dispersant is Span-85; (12) The conductive filler and modified glass powder are added to the organic carrier and mixed evenly, and then ground and degassed to obtain the high temperature electromagnetic shielding slurry; the conductive filler is preferably at least one of Ag, Pd, Pt, ITO or Au; the modified glass powder is preferably aluminoborosilicate glass powder.

7. The multifunctional composite coating according to claim 6, characterized in that, In step (11), the contents of each component in the organic carrier, by mass percentage, are as follows: terpineol 50-70%, butyl carbitol 15-25%, tributyl citrate 15-25%, dispersant 1-5%, ethyl cellulose 2-5%; and / or In step (12), the aluminoborosilicate glass powder contains the following components by mass percentage: SiO2 60-75%, Al2O3 5-15%, B2O3 5-12%, Na2O 5-10%, ZnO 2-8%.

8. The multifunctional composite coating according to claim 6, characterized in that, In step (12), the mass ratio of conductive filler, modified glass powder and organic carrier is (15~45):(15~45):(40~60).

9. A method for preparing a multifunctional composite coating for high-temperature environmental barrier / thermal barrier / electromagnetic shielding according to any one of claims 1 to 8, characterized in that, The preparation method includes the following steps: (1) A bonding layer is prepared on the surface of the composite matrix by spraying process, and then a Yb2Si2O7 environmental barrier layer is prepared on the surface of the bonding layer by atmospheric plasma spraying process; (2) The high-temperature resistant electromagnetic shielding paste is printed onto the surface of the Yb2Si2O7 environmental barrier layer using screen printing technology, and the electromagnetic shielding layer is obtained after drying and sintering. (3) After the electromagnetic shielding layer is sandblasted, an atmospheric plasma spraying process is used to prepare a yttrium-stabilized zirconia thermal barrier layer on the surface of the electromagnetic shielding layer, thereby obtaining the high-temperature environment barrier / thermal barrier / electromagnetic shielding multifunctional composite coating.

10. The preparation method according to claim 9, characterized in that, In step (2), the drying temperature is 100~200℃, and the holding time is 30~60min; and / or The sintering temperature is 750~1000℃, and the holding time is 10~20min.

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