Nanometer structure heat protection coating resistant to long-time high temperature oxidation and preparation method thereof

Abstract

The application discloses a nano-structure heat protection coating resistant to long-time high-temperature oxidation and a preparation method thereof. The nano-structure heat protection coating takes a ceramic matrix composite as a matrix, and a bonding layer and a composite component coating are sprayed on the surface of the matrix in sequence. The specific preparation steps are as follows: a nano-structure self-healing additive / Re2Si2O7 spherical powder is prepared by using a spray granulation method; the ceramic matrix composite is taken as the matrix, and the bonding layer is prepared on the surface of the matrix; and the nano-structure self-healing additive / Re2Si2O7 spherical powder is deposited on the surface of the bonding layer to form the composite component coating. The self-healing additive / Re2Si2O7 is prepared into the nano-structure spherical powder suitable for thermal spraying for the first time, and a method for implementing the high-performance material on the nano-structure coating by thermal spraying is provided. The coating prepared by the application is stable in phase structure at high temperature, the powder does not change phase in the spraying process, and the coating has good thermal expansion coefficient matching with the matrix.

Description

Technical Field

[0001] This invention relates to a high-temperature thermal protective coating and its preparation method, specifically to a nanostructured thermal protective coating resistant to long-term high-temperature oxidation and its preparation method. Background Technology

[0002] With the continuous development of the aerospace and marine industries, the operating temperatures of engines and gas turbines are constantly increasing, and traditional nickel-based superalloys can no longer meet future service requirements. Ceramic matrix composites, represented by silicon-based structural ceramics, are considered the most promising alternatives to nickel-based superalloys for engine hot-end components due to their lightweight and excellent high-temperature mechanical properties. However, ceramic matrix composites are susceptible to corrosion from environmental media during service, leading to rapid material failure. Therefore, environmental barrier coatings have been proposed as an important barrier to protect ceramic matrix composites from environmental corrosion.

[0003] With the continuous development of environmental barrier coatings, rare earth silicate materials have attracted widespread attention from researchers due to their low thermal conductivity, good resistance to water-oxygen corrosion and molten salt corrosion, and excellent stability under the high-temperature airflow environment of engines. Atmospheric plasma, as the most widely used spraying method, causes silicate decomposition and phase transition during the preparation of silicate coatings. However, due to the multiple temperature cycles during service, cracks may occur during use, leading to the growth of thermally grown oxides. This will result in thermal stress accumulation and ultimately vertical crack relaxation, resulting in a short service life. Summary of the Invention

[0004] To address the problems of poor high-temperature long-term service stability, easy phase transformation during spraying, interlayer thermal expansion mismatch, and poor thermal cycling performance leading to coating failure in existing environmental barrier coatings, this invention provides a nanostructured thermal protective coating resistant to long-term high-temperature oxidation and its preparation method. This method, starting from the perspective of raw material design, involves composite self-healing components with commonly used silicate materials. A self-healing additive / Re2Si2O7 sprayable powder is prepared using spray granulation. A self-healing component / silicate composite coating is constructed using thermal spraying technology. This two-layer coating structure replaces the current three-layer environmental barrier coating system, successfully solving the phase transformation problem during silicate spraying. The coating prepared by this invention exhibits good high-temperature phase stability, a thermal expansion coefficient more compatible with the silicon-based ceramic matrix, and can effectively suppress phase transformations during spraying, resulting in higher high-temperature long-term service stability and thermal cycling life.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A self-healing additive / Re2Si2O7 sprayable powder, made primarily from the self-healing additive and Re2Si2O7, is produced by spray granulation. The powder comprises:

[0007] The self-healing additive is one or more of Si, MoSi2, SiC, TiC, and Al2O3;

[0008] The content of the self-healing additive is 1-60% of the total mass of the sprayable powder;

[0009] In the Re2Si2O7, Re is one or more of Y, Yb, Lu, Er, and Sc.

[0010] A method for preparing the above-mentioned self-healing additive / Re2Si2O7 sprayable powder includes the following steps:

[0011] Step 1: Add deionized water to a ball mill, then add a dispersant. After the dispersant is completely dissolved, add nano-Re2O3 powder, nano-SiO2 powder, and self-healing additive according to the designed Re2Si2O7 ratio and self-healing additive content. Ball mill for 6–24 hours, then add a binder and continue ball milling for 0.5–2 hours to obtain a uniform slurry, wherein:

[0012] The nano Re2O3 powder and nano SiO2 powder have a particle size of 5-60 nm and a purity of 4N grade.

[0013] The dispersant is sodium tripolyphosphate (Na5P3O4). 10 Sodium hexametaphosphate ((NaPO3)6), ammonium citrate (C6H5O7(NH4)3), sodium citrate (C6H5Na3O7) 、 One or more of methylpentanol (C6HO), polyacrylamide (PAM), etc., are used, and the amount of dispersant is 0.03 to 4% of the total mass of the sprayable powder.

[0014] The binder is one of gum arabic (Acacia), polyvinyl alcohol (PVA), polyethylene glycol (PEG), epoxy resin, etc., and the amount of binder used is 0.02-15% of the total mass of the sprayable powder.

[0015] Step 2: After spray granulation and solid-phase sintering, the uniform slurry is used to obtain spherical powder, wherein:

[0016] The solid-state sintering is carried out in a protective atmosphere, which can be one or more of nitrogen, argon, and helium.

[0017] The solid-state sintering conditions are as follows: first, heat the temperature to 350℃ at a rate of 2-15℃ / min and hold for 1-4 hours, then heat the temperature to 1100-1600℃ at a rate of 5-20℃ / min and hold for 0.5-4 hours.

[0018] The particle size of the spherical powder is 25–100 μm;

[0019] The spherical powder is a nanostructured self-healing additive / Re2Si2O7 powder.

[0020] A nanostructured thermal protective coating resistant to long-term high-temperature oxidation, using a ceramic matrix composite material as the substrate, wherein an adhesive layer and a composite component coating are sequentially sprayed onto the substrate surface, wherein:

[0021] The ceramic matrix composite material is one of silicon carbide structural ceramics and silicon nitride structural ceramics;

[0022] The adhesive layer is made of one or more of the following materials: Si, SiC, SiN, MoSi2, Si-HfO2, MoSi2-HfO2, and HfSiO4.

[0023] The thickness of the adhesive layer is 50–150 μm;

[0024] The material of the composite coating is a self-healing additive / Re2Si2O7 sprayable powder;

[0025] The thickness of the composite coating is 80–350 μm.

[0026] A method for preparing the above-mentioned nanostructured thermal protective coating resistant to long-term high-temperature oxidation, such as... Figure 1 As shown, it includes the following steps:

[0027] Step 1: Using spray granulation, nanostructured self-healing additive / Re2Si2O7 spherical powders with different rare earth elements and different self-healing additive contents were prepared.

[0028] Step 1: Add deionized water to the ball mill, then add a dispersant. After the dispersant is completely dissolved, add nano-Re2O3 powder, nano-SiO2 powder, and self-healing additive according to the designed Re2Si2O7 ratio and self-healing additive content. Ball mill for 6–24 hours, then add a binder and continue ball milling for 0.5–2 hours to obtain a uniform slurry, wherein:

[0029] The self-healing additive is one or more of Si, MoSi2, SiC, TiC, and Al2O3;

[0030] The content of the self-healing additive is 1-60% of the total mass of the sprayable powder;

[0031] In the Re2Si2O7, Re is one or more of Y, Yb, Lu, Er, and Sc;

[0032] The nano Re2O3 powder and nano SiO2 powder have a particle size of 5-60 nm and a purity of 4N grade.

[0033] The dispersant is sodium tripolyphosphate (Na5P3O4). 10 Sodium hexametaphosphate ((NaPO3)6), ammonium citrate (C6H5O7(NH4)3), sodium citrate (C6H5Na3O7) 、 One or more of methylpentanol (C6HO), polyacrylamide (PAM), etc., are used, and the amount of dispersant is 0.03 to 4% of the total mass of the sprayable powder;

[0034] The binder is one of gum arabic (Acacia), polyvinyl alcohol (PVA), polyethylene glycol (PEG), epoxy resin, etc., and the amount of binder is 0.02-15% of the total mass of the sprayable powder.

[0035] Steps 1 and 2: After spray granulation and solid-phase sintering, the homogeneous slurry is used to obtain spherical powder, wherein:

[0036] The solid-state sintering is carried out in a protective atmosphere, which can be one or more of nitrogen, argon, and helium.

[0037] The solid-state sintering conditions are as follows: first, heat the temperature to 350℃ at a rate of 2-15℃ / min and hold for 1-4 hours, then heat the temperature to 1100-1600℃ at a rate of 5-20℃ / min and hold for 0.5-4 hours.

[0038] The particle size of the spherical powder is 25–100 μm;

[0039] The spherical powder is a nanostructured self-healing additive / Re2Si2O7 spherical powder;

[0040] Step 2: Using a ceramic matrix composite material as the matrix, its surface is ground and polished to achieve a smooth surface, followed by roughening treatment to create a certain roughness. Then, it is ultrasonically cleaned with ethanol and acetone respectively. After drying, a bonding layer is prepared on its surface using thermal spraying technology, wherein:

[0041] The roughening treatment includes one or more of sandblasting, femtosecond laser processing, and surface chemical etching.

[0042] The thermal spraying technology is one of atmospheric plasma spraying (APS), low-pressure plasma spraying (LPPS), and high-velocity oxygen flame spraying (HVOF).

[0043] When the adhesive layer is prepared by atmospheric plasma spraying, the preparation parameters are as follows: spraying distance is 7-250 mm, powder feeding rate is 8-25 g / min, carrier gas flow rate is 3-14 SCFH, spraying current is 450-700 A, spraying voltage is 40-70 V, main gas flow rate is 25-70 SCFH, auxiliary gas flow rate is 2-18 SCFH, and spraying speed is 10-40 mm / s.

[0044] When the adhesive layer is prepared by supersonic flame spraying, the preparation parameters are as follows: spraying distance is 150-500 mm, powder feeding rate is 10-50 g / min, carrier gas flow rate is 1-8 NLPM, shielding gas flow rate is 150-550 NLPM, fuel flow rate is 80-350 NLPM, oxygen flow rate is 100-400 NLPM, and spraying speed is 20-110 mm / s.

[0045] Step 3: Using atmospheric plasma spraying (APS) technology, the nanostructured self-healing additive / Re2Si2O7 spherical powder obtained in Step 1 is deposited on the surface of the adhesive layer obtained in Step 2 to form a composite coating. This yields a thermally protective coating with a nanostructure, good high-temperature phase stability, a thermal expansion coefficient that is more compatible with the silicon-based ceramic matrix, and maintains phase stability during the spraying process.

[0046] The preparation parameters of the composite coating are as follows: spraying distance of 60-350 mm, powder feeding rate of 5-30 g / min, carrier gas flow rate of 4-165 CFH, spraying current of 400-800 A, spraying voltage of 45-80 V, main gas flow rate of 15-70 SCFH, and auxiliary gas flow rate of 3-20 SCFH.

[0047] Compared with the prior art, the present invention has the following advantages:

[0048] 1. This invention utilizes nanoparticle regranulation technology to prepare Selfhealing additive / Re2Si2O7 into nanostructured spherical powder suitable for thermal spraying for the first time, providing a method for implementing this high-performance material on thermal spraying nanostructured coatings.

[0049] 2. This invention is the first to utilize APS technology to prepare a nanostructured Selfhealing additive / Re2Si2O7 thermal protection coating. This technology has advantages such as high energy, wide applicability of materials, ease of operation, high deposition efficiency, and ease of industrialization.

[0050] 3. The coating prepared by the present invention has a typical multimodal structure, that is, there are fully molten, partially molten and unmolten particles, and the porosity is 4 to 13%. The large number of defects in the coating can increase phonon and photon scattering, thereby reducing the thermal conductivity of the coating, relieving the internal stress of the coating, and improving the service life of the coating.

[0051] 4. The coating prepared by this invention has a stable phase structure at high temperatures, and the powder does not undergo phase change during the spraying process. It has good thermal expansion coefficient matching with the substrate, which significantly improves the service life of existing environmental barrier coatings and has broad application prospects. Attached Figure Description

[0052] Figure 1 A process flow diagram for the preparation of a nanostructured thermal protective coating resistant to long-term high-temperature oxidation;

[0053] Figure 2 Surface morphology of coatings with different amounts of self-healing ingredients added;

[0054] Figure 3 Cross-sectional morphology of coatings with different amounts of self-healing components added;

[0055] Figure 4 XRD patterns of deposited coatings with different amounts of self-healing components. Detailed Implementation

[0056] The technical solution of the present invention will be further described below with reference to the embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0057] Example 1:

[0058] This embodiment provides a method for preparing a nanostructured thermal protective coating resistant to long-term high-temperature oxidation, which is achieved through the following steps:

[0059] Step 1: Add deionized water to a ball mill, then add ammonium citrate dispersant to the deionized water. After the ammonium citrate dispersant is completely dissolved, add nano-Yb₂O₃ powder, nano-SiO₂ powder, self-healing additive SiC nano-powder, and 5mm zirconia grinding balls. Ball mill for 8 hours, then add PVA binder and continue ball milling for 0.5 hours to obtain a uniform slurry. The SiC nano-powder is used at 10% of the total mass of the sprayable powder, and the ammonium citrate is used at a concentration equal to the total mass of the sprayable powder. The amount of PVA is 0.5% of the total mass of the sprayable powder, the mass ratio of deionized water to the sprayable powder is 1:1, and the amount of zirconia grinding balls is twice the total mass of the sprayable powder. The uniform slurry is sprayed, granulated, and solid-state sintered to obtain the sprayable composite powder. The solid-state sintering conditions are as follows: in an argon-protected atmosphere furnace, the temperature is first increased to 350℃ at a rate of 5℃ / min and held for 2 hours, then increased to 1200℃ at a rate of 10℃ / min and held for 1 hour.

[0060] Step 2: Use 80-320 mesh silicon carbide sandpaper to sand the SiC. f After the SiC substrate surface is polished, it is then sandblasted with 60-mesh white corundum to give it a certain roughness. Then, it is ultrasonically cleaned with anhydrous ethanol and acetone for 15 minutes each to obtain a substrate with a certain roughness.

[0061] Step 3: Prepare a Si-HfO2 adhesive layer on the substrate surface using atmospheric plasma spraying technology. The preparation parameters for the adhesive layer are as follows: spraying distance 110 mm, powder feed rate 16 g / min, carrier gas flow rate 10 SCFH, spraying current 570 A, spraying voltage 57 V, main gas flow rate 48 SCFH, auxiliary gas flow rate 12 SCFH, and adhesive layer thickness 100 μm.

[0062] Step 4: The sprayable composite powder obtained in Step 1 is deposited onto the surface of the adhesive layer prepared in Step 3 using atmospheric plasma spraying to obtain a two-layer composite ceramic coating. The preparation parameters for the composite coating are: spraying distance of 120 mm, powder feed rate of 20.0 g / min, carrier gas flow rate of 11 SCFH, spraying current of 720 A, spraying voltage of 72 V, main gas flow rate of 50 SCFH, auxiliary gas flow rate of 10 SCFH, and ceramic layer thickness of 150 μm.

[0063] The surface morphology of the coating prepared in this embodiment is as follows: Figure 2 As shown in c) and d), the overall cladding effect of the coating is good. With the increase of self-healing components, the rice-grain-like submicrostructure on the coating surface increases; the cross-sectional morphology of the coating is as follows. Figure 3As shown in d), e), and f), the overall coating thickness remains uniform, the tortuous interface enhances the locking effect, the element distribution is uniform, no phase transformation occurs, and with the increase of self-healing components, the submicro-porosity in the coating increases, which can increase the coating strain tolerance; the coating XRD pattern is shown in... Figure 4 As shown, no phase change or decomposition occurred on the coating surface; the coating withstood 1000 cycles of thermal cycling at 1400℃ without peeling off, and remained intact after 2000 hours of thermal oxidation at 1400℃.

[0064] Example 2:

[0065] This embodiment provides a method for preparing a nanostructured thermal protective coating resistant to long-term high-temperature oxidation, which is achieved through the following steps:

[0066] Step 1: Add deionized water to a ball mill, then add sodium hexametaphosphate as a dispersant. After the sodium hexametaphosphate dispersant is completely dissolved, add nano-Lu2O3 powder, nano-SiO2 powder, self-healing additive MoSi2 nano-powder, and 3mm zirconia grinding balls. After ball milling for 10 hours, add PVA binder and continue ball milling for 0.5 hours to obtain a uniform slurry. The amount of MoSi2 nano-powder is 15% of the total mass of the sprayable powder, and sodium hexametaphosphate... The amount of [agent] used is 1% of the total mass of the sprayable powder, the amount of PVA used is 0.5% of the total mass of the sprayable powder, the mass ratio of deionized water to the sprayable powder is 1.5:1, and the amount of zirconia grinding balls used is 3 times the total mass of the sprayable powder. The uniform slurry is sprayed and granulated and solid-phase sintered to obtain the sprayable composite powder. The solid-phase sintering conditions are: first, in a vacuum muffle furnace, the temperature is raised to 350℃ at a rate of 4℃ / min and held for 1 hour, then raised to 1300℃ at a rate of 8℃ / min and held for 2 hours.

[0067] Step 2: Use 80-320 grit silicon carbide sandpaper to sand C f After the SiC substrate surface is polished, it is then sandblasted with 60-mesh white corundum to give it a certain roughness. Then, it is ultrasonically cleaned with anhydrous ethanol and acetone for 30 minutes each to obtain a substrate with a certain roughness.

[0068] Step 3: Prepare a Si bonding layer on the substrate surface using atmospheric plasma spraying technology. The bonding layer preparation parameters are as follows: spraying distance 100 mm, powder feed rate 12 g / min, carrier gas flow rate 8 SCFH, spraying current 530 A, spraying voltage 53 V, main gas flow rate 45 SCFH, auxiliary gas flow rate 10 SCFH, and bonding layer thickness 150 μm.

[0069] Step 4: The sprayable composite powder obtained in Step 1 is deposited onto the surface of the adhesive layer prepared in Step 3 using atmospheric plasma spraying to obtain a two-layer composite ceramic coating. The preparation parameters for the composite coating are: spraying distance of 110 mm, powder feed rate of 13.0 g / min, carrier gas flow rate of 10 SCFH, spraying current of 740 A, spraying voltage of 74 V, main gas flow rate of 55 SCFH, auxiliary gas flow rate of 14 SCFH, and ceramic layer thickness of 170 μm.

[0070] Example 3:

[0071] This embodiment provides a method for preparing a nanostructured thermal protective coating resistant to long-term high-temperature oxidation, which is achieved through the following steps:

[0072] Step 1: Add deionized water to a ball mill, then add sodium citrate as a dispersant. After the sodium citrate dispersant is completely dissolved, add nano-Sc2O3 powder, nano-SiO2 powder, self-healing additive TiC nano-powder, and 3mm zirconia grinding balls. After ball milling for 7 hours, add gum arabic as a binder and continue ball milling for 0.5 hours to obtain a uniform slurry. The amount of TiC nano-powder is 10% of the total mass of the sprayable powder, and the amount of sodium citrate is [missing information - likely a percentage]. The amount of gum arabic is 0.8% of the total mass of the sprayable powder, the amount of deionized water to sprayable powder is 0.5% of the total mass of the sprayable powder, the mass ratio of deionized water to sprayable powder is 3:1, and the amount of zirconia grinding balls is 2.5 times the total mass of the sprayable powder. The homogeneous slurry is sprayed and granulated and solid-state sintered to obtain sprayable composite powder. The solid-state sintering conditions are: first, in a helium-protected atmosphere furnace, the temperature is raised to 350℃ at a rate of 3℃ / min and held for 2h, then raised to 1400℃ at a rate of 10℃ / min and held for 1.5h.

[0073] Step 2: Use 80-320 grit silicon carbide sandpaper to sand C f After the SiC substrate surface is polished, it is then sandblasted with 60-mesh white corundum to give it a certain roughness. Then, it is ultrasonically cleaned with anhydrous ethanol and acetone for 20 minutes each to obtain a substrate with a certain roughness.

[0074] Step 3: Prepare a Si bonding layer on the substrate surface using high-velocity plasma spraying (HVOF) technology. The bonding layer preparation parameters are: spraying distance 350 mm, powder feed rate 30 g / min, oxygen flow rate 1400 SLPM, kerosene flow rate 20 / h, spray gun moving speed 750 mm / s, and the bonding layer thickness is 140 μm.

[0075] Step 4: The sprayable composite powder obtained in Step 1 is deposited onto the surface of the adhesive layer prepared in Step 3 using atmospheric plasma spraying to obtain a two-layer composite ceramic coating. The preparation parameters for the composite coating are: spraying distance of 100 mm, powder feed rate of 14.5 g / min, carrier gas flow rate of 12 SCFH, spraying current of 710 A, spraying voltage of 67 V, main gas flow rate of 52 SCFH, auxiliary gas flow rate of 13 SCFH, and ceramic layer thickness of 180 μm.

[0076] Example 4:

[0077] The difference between this embodiment and Example 1 is that the amount of SiC nanoparticles used is 5% of the total mass of the sprayable powder. The surface morphology of the coating prepared in this embodiment is as follows. Figure 2 As shown in a) and b), the cross-sectional morphology of the coating is as follows: Figure 3 As shown in a), b), and c), the coating XRD patterns are as follows: Figure 4 As shown.

[0078] Example 5:

[0079] The difference between this embodiment and Example 1 is that the amount of SiC nanoparticles used is 15% of the total mass of the sprayable powder. The surface morphology of the coating prepared in this embodiment is as follows. Figure 2 As shown in e) and f), the cross-sectional morphology of the coating is as follows: Figure 3 As shown in g), h), i), the coating XRD patterns are as follows: Figure 4 As shown.

[0080] Example 6:

[0081] The difference between this embodiment and Example 1 is that the amount of SiC nanoparticles used is 20% of the total mass of the sprayable powder. The surface morphology of the coating prepared in this embodiment is as follows. Figure 2 As shown in g) and h), the cross-sectional morphology of the coating is as follows: Figure 3 As shown in j), k), l), the coating XRD patterns are as follows: Figure 4 As shown.

Claims

1. A self-healing additive / Re2Si2O7 sprayable powder, characterized in that... The sprayable powder is mainly composed of a self-healing additive and Re2Si2O7, and is formed by spray granulation. The self-healing additive is one or more of Si, MoSi2, SiC, TiC, and Al2O3; the content of the self-healing additive is 1-60% of the total mass of the sprayable powder; and in the Re2Si2O7, Re is one or more of Y, Yb, Lu, Er, and Sc. The specific preparation steps are as follows: Step 1: Add deionized water to a ball mill, then add a dispersant. After the dispersant is completely dissolved, add nano-Re2O3 powder, nano-SiO2 powder, and self-healing additive according to the designed Re2Si2O7 ratio and self-healing additive content. Ball mill for 6-24 hours, then add a binder and continue ball milling for 0.5-2 hours to obtain a uniform slurry. The nano-Re2O3 powder and nano-SiO2 powder have a particle size of 5-60 nm; the dispersant is used at 0.03-4% of the total mass of the sprayable powder; and the binder is used at 0.02-15% of the total mass of the sprayable powder. Step 2: After spray granulation and solid-state sintering, the uniform slurry is used to obtain spherical powder. The solid-state sintering conditions are as follows: first, the temperature is raised to 350℃ at a rate of 2~15℃ / min and held for 1~4h, then the temperature is raised to 1100~1600℃ at a rate of 5~20℃ / min and held for 0.5~4h.

2. A method for preparing the self-healing additive / Re2Si2O7 sprayable powder according to claim 1, characterized in that... The method includes the following steps: Step 1: Add deionized water to a ball mill, then add a dispersant. After the dispersant is completely dissolved, add nano-Re2O3 powder, nano-SiO2 powder, and self-healing additive according to the designed Re2Si2O7 ratio and self-healing additive content. Ball mill for 6-24 hours, then add a binder and continue ball milling for 0.5-2 hours to obtain a uniform slurry. The amount of dispersant is 0.03-4% of the total mass of the sprayable powder; the amount of binder is 0.02-15% of the total mass of the sprayable powder. Step 2: After spray granulation and solid-state sintering, the uniform slurry is used to obtain spherical powder. The solid-state sintering conditions are as follows: first, the temperature is raised to 350℃ at a rate of 2~15℃ / min and held for 1~4h, then the temperature is raised to 1100~1600℃ at a rate of 5~20℃ / min and held for 0.5~4h.

3. The method for preparing the self-healing additive / Re2Si2O7 sprayable powder according to claim 2, characterized in that... The nano-Re2O3 powder and nano-SiO2 powder have a purity of 4N; the dispersant is one or more of sodium tripolyphosphate, sodium hexametaphosphate, ammonium citrate, sodium citrate, methylpentanol, and polyacrylamide; the binder is one of gum arabic, polyvinyl alcohol, polyethylene glycol, and epoxy resin; the solid-state sintering is carried out in a protective atmosphere, which is one or more of nitrogen, argon, and helium; the particle size of the spherical powder is 25~100μm.

4. A nanostructured thermal protective coating resistant to prolonged high-temperature oxidation, characterized in that... The nanostructured thermal protective coating uses a ceramic matrix composite material as the substrate, and an adhesive layer and a composite component coating are sequentially sprayed onto the substrate surface, wherein: the material of the composite component coating is the self-healing additive / Re2Si2O7 sprayable powder as described in claim 1.

5. The nanostructured thermal protective coating resistant to long-term high-temperature oxidation according to claim 4, characterized in that... The ceramic matrix composite material is one of silicon carbide structural ceramics and silicon nitride structural ceramics; the adhesive layer is one or more of Si, SiC, SiN, MoSi2, Si-HfO2, MoSi2-HfO2, and HfSiO4; the thickness of the adhesive layer is 50~150μm; and the thickness of the composite coating is 80~350μm.

6. A method for preparing a nanostructured thermal protective coating resistant to prolonged high-temperature oxidation as described in any one of claims 4-5, characterized in that... The method includes the following steps: Step 1: Prepare nanostructured self-healing additive / Re2Si2O7 spherical powder using spray granulation: Step 1: Add deionized water to a ball mill, then add a dispersant. After the dispersant is completely dissolved, add nano-Re2O3 powder, nano-SiO2 powder, and self-healing additive according to the designed Re2Si2O7 ratio and self-healing additive content. Ball mill for 6-24 hours, then add a binder and continue ball milling for 0.5-2 hours to obtain a uniform slurry. The amount of dispersant is 0.03-4% of the total mass of the sprayable powder; the amount of binder is 0.02-15% of the total mass of the sprayable powder. Step 1 and 2: After spray granulation and solid-state sintering, the uniform slurry is used to obtain spherical powder. The solid-state sintering conditions are as follows: first, the temperature is raised to 350℃ at a rate of 2~15℃ / min and held for 1~4h, then the temperature is raised to 1100~1600℃ at a rate of 5~20℃ / min and held for 0.5~4h. Step 2: Using ceramic matrix composite material as the matrix, the surface is polished and smoothed, then roughened. It is then ultrasonically cleaned with ethanol and acetone respectively, and after drying, an adhesive layer is prepared on its surface using thermal spraying technology. Step 3: Using atmospheric plasma spraying technology, the nanostructured self-healing additive / Re2Si2O7 spherical powder obtained in Step 1 is deposited on the surface of the adhesive layer obtained in Step 2 to form a composite coating.

7. The method for preparing the nanostructured thermal protective coating resistant to long-term high-temperature oxidation according to claim 6, characterized in that... The nano-Re2O3 powder and nano-SiO2 powder have a particle size of 5-60 nm and a purity of 4N grade; the dispersant is one or more of sodium tripolyphosphate, sodium hexametaphosphate, ammonium citrate, sodium citrate, methylpentanol, and polyacrylamide; the binder is one of gum arabic, polyvinyl alcohol, polyethylene glycol, and epoxy resin; the solid-state sintering is carried out in a protective atmosphere, which is one or more of nitrogen, argon, and helium; the spherical powder has a particle size of 25-100 μm.

8. The method for preparing the nanostructured thermal protective coating resistant to long-term high-temperature oxidation according to claim 6, characterized in that... The roughening treatment includes one or more of sandblasting, femtosecond laser processing, and surface chemical etching; the thermal spraying technology is one of atmospheric plasma spraying, low-pressure plasma spraying, and supersonic flame spraying.

9. The method for preparing the nanostructured thermal protective coating resistant to long-term high-temperature oxidation according to claim 8, characterized in that... When the adhesive layer is prepared by atmospheric plasma spraying, the preparation parameters are as follows: spraying distance 7~250mm, powder feeding rate 8~25g / min, carrier gas flow rate 3~14SCFH, spraying current 450~700A, spraying voltage 40~70V, main gas flow rate 25~70SCFH, auxiliary gas flow rate 2~18SCFH, and spraying speed 10~40mm / s. When the adhesive layer is prepared by supersonic flame spraying, the preparation parameters are as follows: spraying distance 150~500mm, powder feeding rate 10~50g / min, carrier gas flow rate 1~8NLPM, shielding gas flow rate 150~550NLPM, fuel flow rate 80~350NLPM, oxygen flow rate 100~400NLPM, and spraying speed 20~110mm / s.

10. The method for preparing the nanostructured thermal protective coating resistant to long-term high-temperature oxidation according to claim 6, characterized in that... The preparation parameters of the composite coating are as follows: spraying distance of 60~350mm, powder feeding rate of 5~30g / min, carrier gas flow rate of 4~16 SCFH, spraying current of 400~800A, spraying voltage of 45~80V, main gas flow rate of 15~70 SCFH, and auxiliary gas flow rate of 3~20 SCFH; the thickness of the composite coating is 80~350μm.

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