Environmental barrier-infrared stealth coating and preparation method thereof

Abstract

The invention provides an environmental barrier-infrared stealth coating and a preparation method thereof. The environmental barrier-infrared stealth coating comprises a SiC-based ceramic matrix, a bonding layer, a middle layer and an infrared stealth layer which are sequentially stacked, the surface of one side, relatively close to the infrared stealth layer, of the middle layer is provided with at least one etching area, the infrared stealth layer comprises ceramic columnar crystals, ceramic particles and columnar cavities between every two adjacent ceramic columnar crystals, the ceramic particles are filled in the etching areas, the ceramic columnar crystals are located in non-etching areas of the surface, provided with the etching areas, of the middle layer, and the ceramic particles are located in the columnar cavities between every two adjacent ceramic columnar crystals. And the columnar cavity is positioned above the ceramic particles. The environmental barrier-infrared stealth coating provided by the invention has excellent high-temperature corrosion resistance and infrared stealth performance.

Description

Technical Field

[0001] The present application relates to the technical field of high-temperature protective coatings, and in particular to an environmental barrier-infrared stealth coating and a preparation method thereof. Background Art

[0002] SiC f / SiC ceramic matrix composites (CMC) have low density, excellent high temperature mechanical properties and good oxidation resistance, and are one of the main candidate materials for high temperature structural components of the new generation of aircraft engines. At high temperatures, the surface of the SiC matrix is ​​oxidized to form a SiO2 protective layer, but under actual service conditions, the water vapor in the high temperature gas reacts with SiO2 to generate volatile Si(OH)4 and cause SiC f / SiC components degrade rapidly, so environmental barrier coatings that can isolate water vapor came into being. Environmental barrier coatings used in aircraft engine tail nozzle components not only have to face the erosion of high-temperature water vapor, but also have to deal with the detection of infrared guided weapons.

[0003] At present, more than 95% of the detection sources of mainstream infrared guided weapons come from the tail of the engine (the tail nozzle components and the tail flame). According to the Stefan-Boltzmann law (M=εσT 4 ) It can be seen that the increase in service temperature will lead to a sharp increase in the infrared radiation intensity of the hot end components, and the risk of heat exposure will increase. It is crucial to improve the safety and combat effectiveness of aircraft by preparing a high-temperature coating on the surface of CMC ceramic-based components that can inhibit water vapor corrosion and achieve infrared stealth effects, thereby reducing the impact of water vapor corrosion, improving service safety, extending service life, and reducing the probability of hot end components being detected and identified by infrared detectors. Summary of the invention

[0004] Based on this, the present application provides an environmental barrier-infrared stealth coating and a preparation method thereof to improve the high-temperature corrosion resistance and infrared stealth performance of SiC-based ceramic hot end components.

[0005] The first aspect of the present application provides an environmental barrier-infrared stealth coating, comprising a SiC-based ceramic substrate, an adhesive layer, an intermediate layer and an infrared stealth layer stacked in sequence; the intermediate layer is provided with at least one etching area on the surface of one side relatively adjacent to the infrared stealth layer, the infrared stealth layer comprises ceramic columnar crystals, ceramic particles and a columnar cavity between two adjacent ceramic columnar crystals, the ceramic particles are filled in the etching area, the ceramic columnar crystals are located in the unetched area of ​​the surface of the intermediate layer having the etching area, and the columnar cavity is located above the ceramic particles.

[0006] In some embodiments, the infrared stealth layer has at least one of the following features (1)-(4):

[0007] (1) The material of the infrared stealth layer includes one or more of rare earth zirconates and rare earth hafnates;

[0008] (2) The width of the ceramic columnar crystal is 10 μm-40 μm;

[0009] (3) The thickness of the infrared stealth layer is 100 μm-150 μm;

[0010] (4) The average particle size of the ceramic particles is 0.5 μm-10 μm;

[0011] (5) The volume proportion of the ceramic columnar crystals in the infrared stealth layer is 40%-80%;

[0012] (6) The volume proportion of the ceramic particles in the infrared stealth layer is 5%-30%;

[0013] (7) The volume proportion of the columnar cavity in the infrared stealth layer is 10%-40%;

[0014] (8) The columnar cavity penetrates the infrared stealth layer along the thickness direction of the infrared stealth layer, and the width of the columnar cavity is 8 μm to 15 μm.

[0015] In some embodiments, the intermediate layer has at least one of the following features (1)-(4):

[0016] (1) The depth of the etching area is 5 μm-50 μm, the width of the etching area is 10 μm-30 μm, and the distance between two adjacent etching areas is 20 μm-200 μm;

[0017] (2) The thickness of the intermediate layer is 80 μm-150 μm;

[0018] (3) The material of the intermediate layer includes one or both of ytterbium silicate and ytterbium disilicate;

[0019] (4) The porosity of the intermediate layer is less than 10%.

[0020] In some embodiments, the bonding layer has at least one of the following features (1)-(2):

[0021] (1) The thickness of the adhesive layer is 60 μm-125 μm;

[0022] (2) The material of the adhesive layer includes Si.

[0023] In some embodiments, the SiC-based ceramic matrix is ​​selected from a silicon carbide matrix or a silicon carbide fiber reinforced silicon carbide ceramic-based composite matrix.

[0024] The second aspect of the present application provides a method for preparing an environmental barrier-infrared stealth coating, comprising the following steps:

[0025] Performing sandblasting pretreatment on at least one side surface of the SiC-based ceramic substrate;

[0026] forming an adhesive layer on the surface of the SiC-based ceramic substrate after sandblasting pretreatment, and forming an intermediate layer on the surface of the adhesive layer relatively away from the SiC-based ceramic substrate;

[0027] Performing an etching process on the intermediate layer to form at least one etching area on a surface of the intermediate layer relatively far from the bonding layer;

[0028] An infrared stealth layer is formed on the surface of the intermediate layer having the etching area, and the infrared stealth layer comprises ceramic columnar crystals, ceramic particles and a columnar cavity between two adjacent ceramic columnar crystals, the ceramic particles are filled in the etching area, the ceramic columnar crystals are located in the unetched area of ​​the surface of the intermediate layer having the etching area, and the columnar cavity is located above the ceramic particles.

[0029] In some embodiments, the bonding layer is prepared by atmospheric plasma spraying.

[0030] In some embodiments, the method for preparing the bonding layer includes at least one of the following conditions (1)-(6):

[0031] (1) The spraying current of the atmospheric plasma spraying is 500A-700A;

[0032] (2) The spraying power of the atmospheric plasma spraying is 35KW-40KW;

[0033] (3) The gas used in the atmospheric plasma spraying includes argon gas, and the argon gas flow rate is 30slpm-40slpm;

[0034] (4) The gas used in the atmospheric plasma spraying includes hydrogen, and the hydrogen flow rate is 5slpm-8slpm;

[0035] (5) The powder feeding rate of the atmospheric plasma spraying is 25g / min-35g / min;

[0036] (6) The spraying distance of the atmospheric plasma spraying is 80 mm-100 mm.

[0037] In some embodiments, the preparation method of the intermediate layer includes atmospheric plasma spraying.

[0038] In some embodiments, the method for preparing the intermediate layer includes at least one of the following conditions (1)-(6):

[0039] (1) The spraying current of the atmospheric plasma spraying is 500A-700A;

[0040] (2) The spraying power of the atmospheric plasma spraying is 40KW-45KW;

[0041] (3) The gas used in the atmospheric plasma spraying includes argon gas, and the argon gas flow rate is 30slpm-40slpm;

[0042] (4) The gas used in the atmospheric plasma spraying includes hydrogen, and the hydrogen flow rate is 8slpm-12slpm;

[0043] (5) The powder feeding rate of the atmospheric plasma spraying is 25g / min-35g / min;

[0044] (6) The spraying distance of the atmospheric plasma spraying is 80 mm-100 mm.

[0045] In some embodiments, the preparation method of the intermediate layer includes plasma physical vapor deposition.

[0046] In some embodiments, the method for preparing the intermediate layer includes at least one of the following conditions (1)-(5):

[0047] (1) The deposition current of the plasma physical vapor deposition is 1100A-1200A;

[0048] (2) The deposition power of the plasma physical vapor deposition is 30KW-40KW;

[0049] (3) The plasma gas used in the plasma physical vapor deposition includes argon and helium, the argon flow rate is 20slpm-40slpm, and the helium flow rate is 30slpm-60slpm;

[0050] (4) The powder feeding rate of the plasma physical vapor deposition is 8g / min-10g / min;

[0051] (5) The spraying distance of the plasma physical vapor deposition is 600mm-800mm.

[0052] In some embodiments, a pulse laser is used to etch the intermediate layer.

[0053] In some embodiments, the etching process includes at least one of the following conditions (1)-(7):

[0054] (1) The laser center wavelength of the pulsed laser is 355 nm;

[0055] (2) The laser focus spot diameter of the pulse laser is 10 μm-20 μm;

[0056] (3) The pulse width of the pulse laser is 10ns-20ns;

[0057] (4) The laser power of the pulsed laser is 3W-10W;

[0058] (5) The repetition frequency of the pulsed laser is 10kHz-30kHz;

[0059] (6) The scanning speed of the pulse laser is 50 mm / s-200 mm / s;

[0060] (7) The scanning repetition number of the pulse laser is 1 to 5 times.

[0061] In some embodiments, the method for preparing the infrared stealth layer includes plasma physical vapor deposition.

[0062] In some embodiments, the method for preparing the infrared stealth layer includes at least one of the following conditions (1)-(7):

[0063] (1) The vacuum degree of the plasma physical vapor deposition is 1 mbar-5 mbar;

[0064] (2) The working gas used in the plasma physical vapor deposition includes argon and helium, the argon flow rate is 20slpm-40slpm, and the helium flow rate is 30slpm-60slpm;

[0065] (3) The spray gun distance of the plasma physical vapor deposition is 800mm-1200mm;

[0066] (4) The deposition current of the plasma physical vapor deposition is 1800A-2100A;

[0067] (5) The deposition power of the plasma physical vapor deposition is 55kW-65kW;

[0068] (6) The powder feeding rate of the plasma physical vapor deposition is 8g / min-10g / min;

[0069] (7) The sample preheating temperature of the plasma physical vapor deposition is 600°C-800°C.

[0070] In the environmental barrier-infrared stealth coating provided above, the bonding layer can be rapidly oxidized under high-temperature service conditions to generate a protective SiO2 oxide film to prevent the SiC-based ceramic substrate from being corroded; the intermediate layer has a dense structure, which can inhibit the contact and reaction between high-temperature water vapor and the SiO2 oxide film, reduce the generation and volatilization rate of Si(OH)4, and the bonding layer and the intermediate layer work together to avoid the performance degradation of the SiC-based ceramic substrate. On the one hand, the infrared stealth layer can achieve the diffraction extinction effect of its own radiated infrared rays through the columnar cavity to reduce the infrared emissivity. On the other hand, it can achieve heat insulation through ceramic columnar crystals and ceramic particles with low thermal conductivity to reduce the surface temperature. The two work together to reduce the infrared radiation intensity of the components and achieve infrared stealth. Therefore, the environmental barrier-infrared stealth coating provided by the present application has excellent high-temperature corrosion resistance and infrared stealth performance.

[0071] In the preparation method of the environmental barrier-infrared stealth coating provided above, when the intermediate layer is etched, the etched area is laser remelted, and a dense structure is formed after cooling and solidification, which can further improve the compactness and water vapor corrosion resistance of the intermediate layer. The etching area set on the surface of the intermediate layer can induce the aggregation of ceramic particles during the deposition of the infrared stealth layer, so that the etching area contains more ceramic particles, and a columnar cavity is formed above the ceramic particles, and a micro-nano composite structure containing ceramic columnar crystals, ceramic particles and columnar cavities can be formed in one step. At the same time, the columnar cavity can improve the strain tolerance of the infrared stealth layer, reduce the probability of interface failure due to the mismatch of the thermal expansion coefficients of the infrared stealth layer and the intermediate layer, extend the service life of the coating, and expand the range of choices for infrared stealth layer materials. In addition, the preparation method has high efficiency, strong repeatability, and flexible and controllable process parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the technical solutions in the embodiments of the present application and to more completely understand the present application and its beneficial effects, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0073] Figure 1 A schematic diagram of the structure of an environmental barrier-infrared stealth coating provided in one embodiment;

[0074] Figure 2 The cross-sectional electron backscatter diffraction patterns of the coatings prepared in Example 1, Example 2 and Comparative Example 1;

[0075] Figure 3 The infrared emissivity of the coatings and SiC in the 3 μm to 5 μm band at different temperatures obtained in Example 1, Example 2, Comparative Example 1 and Comparative Example 3 (SiC), wherein Figure 3 (a) and Figure 3 (b) shows the results at 800°C and 1100°C respectively. DETAILED DESCRIPTION

[0076] For ease of understanding of the present invention, the application will be described more fully below with reference to relevant embodiments. The following provides preferred embodiments of the application. However, the application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the application more thorough and comprehensive.

[0077] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0078] The terms "and / or", "or / and", and "and / or" used herein include any one of two or more related listed items, and also include any and all combinations of the related listed items, wherein the any and all combinations include any combination of two related listed items, any more related listed items, or all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that in the present application, the technical solution undoubtedly includes technical solutions connected by "logical and", and also undoubtedly includes technical solutions connected by "logical or".

[0079] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0080] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0081] Only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and likewise any upper limit can be combined with any other upper limit to form an unspecified range. In addition, each separately disclosed point or single value can itself be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an unspecified range.

[0082] The temperature parameters in this application, unless otherwise specified, allow both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0083] In this application, unless otherwise specified, the size, particle size, and diameter generally refer to the average value. In this application, "particle size" and "particle size" have the same definition, both representing the average particle size of a sphere or a spheroid.

[0084] Herein, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc., shall be based on the ability to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0085] In the present application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of the present application.

[0086] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0087] In the description of the application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0088] If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution. If there is no special description, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0089] If there is no special explanation, all the steps of the present application can be performed sequentially or randomly, preferably sequentially.

[0090] It is very important to prepare a high-temperature coating on the surface of CMC ceramic-based components that can inhibit water vapor corrosion and achieve infrared stealth effect, so as to reduce the impact of water vapor corrosion, improve service safety, extend service life, and reduce the probability of hot end components being detected and identified by infrared detectors. Reducing the intensity of infrared radiation can be achieved by reducing the surface emissivity (ε) of the component or reducing the surface temperature (T). Precious metal materials have extremely low emissivity, and ceramic coatings coated with precious metal coatings or filled with precious metal particles can significantly reduce the radiation intensity of components. The Chinese patent application with publication number CN110002900A discloses that the composite coating prepared on the surface of the CMC substrate uses Bi2O3-ZnO glass containing precious metal fillers as a low emissivity layer and mullite / BSAS composite system as an antioxidant layer. The emissivity of the composite coating at 900°C can be as low as 0.14, and it has good high temperature resistance and thermal shock resistance. The Chinese patent application with publication number CN111732457A discloses that the infrared emissivity of the coating is reduced by using precious metal Pt powder as a filler.

[0091] However, since there is only a weak interfacial van der Waals force between the metal filler and the non-metallic coating material, and the thermal expansion coefficients of the two are quite different, under high temperature conditions, the metal-non-metallic interface is very easy to crack and cause the overall failure of the coating. In addition, when the metal film is used as a low-emissivity surface layer, it is very easy to be damaged by the high-speed scouring environment of the combustion chamber, resulting in a decrease in coating performance and a shortened life. Furthermore, the melting point of metal materials limits their use at higher temperatures. Therefore, it is urgent to develop an environmental barrier-infrared stealth coating that can be applied to higher service temperatures and more severe service environments.

[0092] One or more embodiments of the present application provide an environmental barrier-infrared stealth coating, comprising a SiC-based ceramic substrate, an adhesive layer, an intermediate layer and an infrared stealth layer stacked in sequence; at least one etching area is arranged on the surface of the intermediate layer on the side adjacent to the infrared stealth layer, the infrared stealth layer contains ceramic columnar crystals, ceramic particles and columnar cavities between two adjacent ceramic columnar crystals, the ceramic particles are filled in the etching area, the ceramic columnar crystals are located in the unetched area of ​​the surface of the intermediate layer having the etching area, and the columnar cavities are located above the ceramic particles.

[0093] It should be noted that when a plurality of etching areas are arranged on the surface of the intermediate layer on one side adjacent to the infrared stealth layer, the shape and arrangement of the etching areas may be a periodic grid structure.

[0094] Understandably, in the environmental barrier-infrared stealth coating provided above, the bonding layer can be rapidly oxidized under high-temperature service conditions to generate a protective SiO2 oxide film to prevent the SiC-based ceramic substrate from being corroded; the intermediate layer has a dense structure, which can inhibit the contact and reaction between high-temperature water vapor and the SiO2 oxide film, reduce the generation and volatilization rate of Si(OH)4, and the combined action of the bonding layer and the intermediate layer can avoid the performance degradation of the SiC-based ceramic substrate. On the one hand, the infrared stealth layer can achieve the diffraction extinction effect of its own radiated infrared rays through the columnar cavity to reduce the infrared emissivity. On the other hand, it can achieve heat insulation through ceramic columnar crystals and ceramic particles with low thermal conductivity to reduce the surface temperature. The two work together to reduce the infrared radiation intensity of the components and achieve infrared stealth. Therefore, the environmental barrier-infrared stealth coating provided by the present application has excellent high-temperature corrosion resistance and infrared stealth performance.

[0095] like Figure 1 As shown, as a non-limiting example, the environmental barrier-infrared stealth coating includes a SiC-based ceramic substrate 1, an adhesive layer 2, an intermediate layer 3 and an infrared stealth layer 4 which are stacked in sequence; at least one etching area 31 is arranged on the surface of the intermediate layer 3 on one side adjacent to the infrared stealth layer 4, the infrared stealth layer 4 comprises ceramic columnar crystals 41, ceramic particles 42 and a columnar cavity 43 between two adjacent ceramic columnar crystals, the ceramic particles 42 are filled in the etching area 31, the ceramic columnar crystals 41 are located in the unetched area of ​​the surface of the intermediate layer 3 having the etching area 31, and the columnar cavity 43 is located above the ceramic particles 42.

[0096] In some embodiments, the material of the infrared stealth layer includes one or more of rare earth zirconates and rare earth hafnates. Optionally, the rare earth zirconate includes (Gd 0.9 Yb 0.1 )2Zr2O7.

[0097] As a possible implementation, the width of the ceramic columnar crystal is 10 μm-40 μm; for example, it can be but not limited to 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, 32 μm, 34 μm, 36 μm, 38 μm, 40 μm or a range between any two of the above widths. Therefore, the ceramic columnar crystal has good strain tolerance, which is beneficial to improving the high temperature service life of the infrared stealth layer.

[0098] It is to be understood that the “width of the ceramic columnar crystal” mentioned above and below refers to the maximum radial length of each ceramic columnar crystal.

[0099] In some optional embodiments, the thickness of the infrared stealth layer is 100 μm-150 μm; for example, it can be but not limited to 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 125 μm, 130 μm, 135 μm, 140 μm, 145 μm, 150 μm or a range between any two of the above thicknesses. When the thickness of the infrared stealth layer is within the above range, it has a significant heat insulation effect and can significantly reduce the surface temperature of the component. Optionally, the thickness of the infrared stealth layer is 110 μm-120 μm.

[0100] In some embodiments, the average particle size of the ceramic particles is 0.5 μm-10 μm; for example, it can be but not limited to 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm or the range between any two of the above particle sizes, etc. Thus, it has a certain heat insulation effect.

[0101] In some optional embodiments, the average particle size of the ceramic particles is 5 μm-9 μm.

[0102] In some exemplary embodiments, the volume proportion of ceramic columnar crystals in the infrared stealth layer is 40%-80%, for example, but not limited to 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or a range between any two of the above volume proportions, etc. Thus, the infrared stealth layer has low infrared emissivity, good thermal insulation performance and strain tolerance.

[0103] As a possible implementation method, the volume proportion of ceramic columnar crystals in the infrared stealth layer is 65%-80%.

[0104] In some embodiments, the volume proportion of ceramic particles in the infrared stealth layer is 5%-30%, for example, but not limited to 5%, 10%, 15%, 20%, 25%, 30%, or a range between any two of the above volume proportions, etc. Thus, the infrared stealth layer has a lower infrared emissivity and good heat insulation performance.

[0105] In some embodiments, the volume proportion of ceramic particles in the infrared stealth layer is 5%-18%.

[0106] In some embodiments, the volume proportion of the columnar cavity in the infrared stealth layer is 10%-40%, for example, but not limited to 10%, 15%, 20%, 25%, 30%, 35%, 40%, or a range between any two of the above volume proportions, etc. Thus, the infrared stealth layer has low infrared emissivity, good thermal insulation performance and strain tolerance.

[0107] In some optional embodiments, the volume of the columnar cavity in the infrared stealth layer accounts for 15%-25%.

[0108] As a possible implementation, the columnar cavity penetrates the infrared stealth layer along the thickness direction of the infrared stealth layer, and the width of the columnar cavity is 8μm-15μm; for example, it can be but not limited to 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 10.5μm, 11μm, 11.5μm, 12μm, 12.5μm, 13μm, 13.5μm, 14μm, 14.5μm, 15μm or the range between any two of the above particle sizes. When the width of the columnar cavity is within the above range, it is beneficial for the infrared stealth layer to reduce the infrared radiation by diffraction extinction while maintaining a high heat insulation capacity, and jointly reduce the infrared radiation intensity on the surface of the component by reducing the emissivity and lowering the temperature.

[0109] In some optional embodiments, the width of the columnar cavity is 12 μm-15 μm.

[0110] It should be noted that the "width of the columnar cavity" mentioned in the context refers to the longest straight-line distance between two points on the edge of the columnar cavity on a plane perpendicular to the thickness direction of the infrared stealth layer.

[0111] In some exemplary embodiments, the depth of the etched area is 5 μm-50 μm; for example, it can be but not limited to 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, or a range between any two of the above depths. Optionally, the depth of the etched area is 30 μm-50 μm.

[0112] As a possible implementation, the width of the etched area is 10 μm-30 μm, for example, but not limited to 10 μm, 15 μm, 20 μm, 25 μm, 30 μm or a range between any two of the above widths.

[0113] In some optional embodiments, the spacing between two adjacent etching areas is 20 μm-200 μm; for example, it can be but not limited to 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm or a range between any two of the above spacings, etc. Optionally, the spacing between two adjacent etching areas is 50 μm-110 μm.

[0114] When the depth, width and spacing of the etching area are respectively within the above ranges, it is beneficial for the ceramic columnar crystals, ceramic particles and columnar cavities of the infrared stealth layer to be within an appropriate range.

[0115] It should be noted that the depth of the etching zone mentioned above refers to the distance from the surface of the intermediate layer relatively close to the low infrared reflectivity layer to the deepest point along the direction perpendicular to the surface; the width of the etching zone refers to the longest straight line length of the etching zone along the direction parallel to the surface of the intermediate layer. The spacing between two adjacent etching zones refers to the shortest straight line distance between the edges of two adjacent etching zones on the surface of the intermediate layer.

[0116] In some embodiments, the thickness of the intermediate layer is 80 μm-150 μm; for example, it can be but not limited to 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 125 μm, 130 μm, 135 μm, 140 μm, 145 μm, 150 μm, or a range between any two of the above thicknesses. When the thickness of the intermediate layer is within the above range, the intermediate layer has excellent water vapor corrosion resistance and good strain tolerance.

[0117] In some optional embodiments, the thickness of the intermediate layer is 90 μm-145 μm.

[0118] As a possible implementation, the material of the intermediate layer includes one or both of ytterbium silicate (Yb2SiO5, YbMS) and ytterbium disilicate (Yb2Si2O7, YbDS).

[0119] In some optional embodiments, the structure of the intermediate layer is dense. Optionally, the porosity of the intermediate layer is less than 10%. Thus, the intermediate layer has excellent water vapor corrosion resistance.

[0120] As a possible implementation, the thickness of the adhesive layer is 60 μm-125 μm; for example, it can be but not limited to 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 125 μm or a range between any two of the above thicknesses. As a result, the adhesive layer has excellent strain tolerance, and the environmental barrier-infrared stealth coating has excellent high temperature and long service life. Optionally, the thickness of the adhesive layer is 80 μm-125 μm.

[0121] In some optional embodiments, the material of the bonding layer is Si.

[0122] In some embodiments, the SiC-based ceramic matrix is ​​selected from a silicon carbide matrix or a silicon carbide fiber reinforced silicon carbide ceramic-based composite matrix.

[0123] One or more embodiments of the present application provide a method for preparing an environmental barrier-infrared stealth coating, comprising the following steps:

[0124] At least one side surface of a SiC-based ceramic substrate is pre-treated by sandblasting; a bonding layer is formed on the surface of the SiC-based ceramic substrate after the sandblasting pre-treatment, and an intermediate layer is formed on the surface of the bonding layer relatively far away from the SiC-based ceramic substrate; the intermediate layer is etched to form at least one etching area on the surface of the intermediate layer relatively far away from the bonding layer; an infrared stealth layer is formed on the surface of the intermediate layer having the etching area, the infrared stealth layer comprises ceramic columnar crystals, ceramic particles and columnar cavities between two adjacent ceramic columnar crystals, the ceramic particles are filled in the etching area, the ceramic columnar crystals are located in the unetched area of ​​the surface of the intermediate layer having the etching area, and the columnar cavities are located above the ceramic particles.

[0125] Understandably, in the preparation method of the environmental barrier-infrared stealth coating provided by the present application, when the intermediate layer is etched, the etched area is laser remelted, and a dense structure is generated after cooling and solidification, which can further improve the compactness and water vapor corrosion resistance of the intermediate layer. The etching area set on the surface of the intermediate layer can induce the aggregation of ceramic particles during the deposition of the infrared stealth layer, so that the etching area contains more ceramic particles, and a columnar cavity is formed above the ceramic particles, and a micro-nano composite structure containing ceramic columnar crystals, ceramic particles and columnar cavities can be formed in one step. At the same time, the columnar cavity can improve the strain tolerance of the infrared stealth layer, reduce the probability of interface failure due to the mismatch of the thermal expansion coefficients of the infrared stealth layer and the intermediate layer, extend the service life of the coating, and expand the range of choices for infrared stealth layer materials. In addition, the preparation method has high efficiency, strong repeatability, and flexible and controllable process parameters.

[0126] In some embodiments, the bonding layer is prepared by a method comprising atmospheric plasma spraying.

[0127] As a possible implementation manner, when preparing the bonding layer, the spraying current of the atmospheric plasma spraying is 500A-700A; for example, it can be but not limited to 500A, 520A, 540A, 560A, 580A, 600A, 620A, 640A, 660A, 680A, 700A or a range between any two of the above spraying currents, etc.

[0128] In some optional embodiments, when preparing the bonding layer, the spraying power of the atmospheric plasma spraying is 35KW-40KW; for example, it can be but not limited to 35KW, 36KW, 37KW, 38KW, 39KW, 40KW or a range between any two of the above powers, etc.

[0129] In some embodiments, when preparing the bonding layer, the gas used in the atmospheric plasma spraying includes argon. Further optionally, the argon flow rate is 30slpm-40slpm; for example, it can be but not limited to 30slpm, 32slpm, 34slpm, 36slpm, 38slpm, 40slpm, or a range between any two of the above flow rates.

[0130] In some exemplary embodiments, when preparing the bonding layer, the gas used in the atmospheric plasma spraying includes hydrogen. As a non-limiting example, the hydrogen flow rate is 5slpm-8slpm; for example, it can be but not limited to 5slpm, 6slpm, 7slpm, 8slpm, or a range between any two of the above flow rates.

[0131] In some embodiments, when preparing the bonding layer, the powder feeding rate of atmospheric plasma spraying is 25 g / min-35 g / min; for example, it can be but not limited to 25 g / min, 26 g / min, 27 g / min, 28 g / min, 29 g / min, 30 g / min, 31 g / min, 32 g / min, 33 g / min, 34 g / min, 35 g / min or a range between any two of the above powder feeding rates, etc.

[0132] In some optional embodiments, when preparing the bonding layer, the spraying distance of atmospheric plasma spraying is 80mm-100mm; for example, it can be but not limited to 80mm, 82mm, 84mm, 84mm, 86mm, 88mm, 90mm, 92mm, 94mm, 96mm, 98mm, 100mm or a range between any two of the above distances, etc.

[0133] In some embodiments, the method of preparing the intermediate layer comprises atmospheric plasma spraying.

[0134] In some optional embodiments, when preparing the intermediate layer, the spraying current of atmospheric plasma spraying is 500A-700A; for example, it can be but not limited to 500A, 520A, 540A, 560A, 580A, 600A, 620A, 640A, 660A, 680A, 700A or a range between any two of the above spraying currents, etc.

[0135] In some optional embodiments, when preparing the intermediate layer, the spraying power of atmospheric plasma spraying is 40KW-45KW; for example, it can be but not limited to 40KW, 41KW, 42KW, 43KW, 44KW, 45KW or a range between any two of the above powers, etc.

[0136] In some embodiments, when preparing the intermediate layer, the gas used in the atmospheric plasma spraying includes argon. Further optionally, the argon flow rate is 30slpmslpm-40slpmslpm; for example, it can be but not limited to 30slpm, 32slpm, 34slpm, 36slpm, 38slpm, 40slpm or a range between any two of the above flow rates.

[0137] In some exemplary embodiments, when preparing the intermediate layer, the gas used in the atmospheric plasma spraying includes hydrogen. As a non-limiting example, the hydrogen flow rate is 8slpm-12slpm; for example, it can be but not limited to 8slpm, 9slpm, 10slpm, 11slpm, 12slpm, or a range between any two of the above flow rates.

[0138] In some optional embodiments, when preparing the intermediate layer, the powder feeding rate of atmospheric plasma spraying is 25g / min-35g / min; for example, it can be but not limited to 25g / min, 26g / min, 27g / min, 28g / min, 29g / min, 30g / min, 31g / min, 32g / min, 33g / min, 34g / min, 35g / min or a range between any two of the above powder feeding rates, etc.

[0139] In some embodiments, when preparing the intermediate layer, the spraying distance of atmospheric plasma spraying is 80mm-100mm; for example, it can be but not limited to 80mm, 82mm, 84mm, 84mm, 86mm, 88mm, 90mm, 92mm, 94mm, 96mm, 98mm, 100mm or a range between any two of the above distances.

[0140] In some embodiments, the preparation method of the intermediate layer includes plasma physical vapor deposition.

[0141] In some optional embodiments, when preparing the intermediate layer, the deposition current of plasma physical vapor deposition is 1100A-1200A; for example, it can be but not limited to 1100A, 1120A, 1140A, 1160A, 1180A, 1200A or a range between any two of the above currents.

[0142] In some of the embodiments, when preparing the intermediate layer, the deposition power of plasma physical vapor deposition is 30KW-40KW; for example, it can be but not limited to 30KW, 31KW, 32KW, 33KW, 34KW, 35KW, 36KW, 37KW, 38KW, 39KW, 40KW or a range between any two of the above powers, etc.

[0143] In some optional embodiments, when preparing the intermediate layer, the plasma gas used for plasma physical vapor deposition includes argon and helium. Optionally, the argon flow rate is 20slpm-40slpm; for example, it can be but not limited to 20slpm, 25slpm, 30slpm, 35slpm, 40slpm or the range between any two of the above flow rates. Optionally, the helium flow rate is 30slpm-60slpm; for example, it can be but not limited to 30slpm, 35slpm, 40slpm, 45slpm, 50slpm, 55slpm, 60slpm or the range between any two of the above flow rates.

[0144] In some exemplary embodiments, when preparing the intermediate layer, the powder feeding rate of plasma physical vapor deposition is 8g / min-10g / min; for example, it can be but not limited to 8g / min, 9g / min, 10g / min or a range between any two of the above powder feeding rates.

[0145] As a possible implementation manner, when preparing the intermediate layer, the spraying distance of plasma physical vapor deposition is 600mm-800mm; for example, it can be but not limited to 600mm, 620mm, 640mm, 660mm, 680mm, 700mm, 720mm, 740mm, 760mm, 780mm, 800mm or the range between any two of the above distances.

[0146] In some embodiments, a pulsed laser is used to etch the intermediate layer.

[0147] In some optional implementations, when performing the etching process, the laser center wavelength of the pulsed laser is 355 nm.

[0148] In some of the embodiments, during etching, the laser focus spot diameter of the pulsed laser is 10 μm-20 μm; for example, it may be but is not limited to 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm or the distance between any two of the above diameters.

[0149] In some exemplary embodiments, during etching, the pulse width of the pulsed laser is 10ns-20ns; for example, it may be but is not limited to 10ns, 12ns, 14ns, 16ns, 18ns, 20ns or a range between any two of the above pulse widths.

[0150] As a possible implementation, during etching, the laser power of the pulsed laser is 3W-10W; for example, it can be but not limited to 3W, 4W, 5W, 6W, 7W, 8W, 9W, 10W or a range between any two of the above powers.

[0151] In some optional embodiments, during etching treatment, the repetition frequency of the pulsed laser is 10kHz-30kHz; for example, it can be but not limited to 10kHz, 12kHz, 14kHz, 16kHz, 18kHz, 20kHz, 22kHz, 24kHz, 26kHz, 28kHz, 30kHz or a range between any two of the above frequencies, etc.

[0152] As a possible implementation mode, during etching, the scanning speed of the pulse laser is 50 mm / s-200 mm / s; for example, it may be but is not limited to 50 mm / s, 70 mm / s, 90 mm / s, 100 mm / s, 120 mm / s, 140 mm / s, 160 mm / s, 180 mm / s, 200 mm / s or a range between any two of the above speeds.

[0153] In some optional embodiments, during etching processing, the scanning repetition number of the pulse laser is 1-5 times; for example, it can be but not limited to 1 time, 2 times, 3 times, 4 times, 5 times or a range between any two of the above values.

[0154] In some embodiments, the method for preparing the infrared stealth layer includes plasma physical vapor deposition.

[0155] In some optional embodiments, when preparing the infrared stealth layer, the vacuum degree of plasma physical vapor deposition is 1 mbar-5 mbar; for example, it can be but not limited to 1 mbar, 2 mbar, 3 mbar, 4 mbar, 5 mbar or a range between any two of the above vacuum degrees, etc.

[0156] In some embodiments, when preparing the infrared stealth layer, the working gas used in the plasma physical vapor deposition includes argon and helium. Optionally, the argon flow rate is 20slpm-40slpm; for example, it can be but not limited to 20slpm, 25slpm, 30slpm, 35slpm, 40slpm or the range between any two of the above flow rates. Optionally, the helium flow rate is 30slpm-60slpm; for example, it can be but not limited to 30slpm, 35slpm, 40slpm, 45slpm, 50slpm, 55slpm, 60slpm or the range between any two of the above flow rates.

[0157] In some optional embodiments, when preparing the infrared stealth layer, the spray gun distance of plasma physical vapor deposition is 800mm-1200mm; for example, it can be but not limited to 800mm, 900mm, 1000mm, 1100mm, 1200mm or a range between any two of the above distances.

[0158] In some of the embodiments, when preparing the infrared stealth layer, the deposition current of plasma physical vapor deposition is 1800A-2100A; for example, it can be but not limited to 1800A, 1850A, 1900A, 1950A, 2000A, 2050A, 2100A or a range between any two of the above currents.

[0159] As a possible implementation mode, when preparing the infrared stealth layer, the deposition power of plasma physical vapor deposition is 55kW-65kW; for example, it can be but not limited to 55kW, 56kW, 57kW, 58kW, 59kW, 60kW, 61kW, 62kW, 63kW, 64kW, 65kW or a range between any two of the above powers, etc.

[0160] In some optional embodiments, when preparing the infrared stealth layer, the powder feeding rate of plasma physical vapor deposition is 8g / min-10g / min; for example, it can be but not limited to 8g / min, 9g / min, 10g / min or a range between any two of the above powder feeding rates.

[0161] As a non-limiting example, when preparing an infrared stealth layer, the sample preheating temperature of plasma physical vapor deposition is 600°C-800°C; for example, it can be but not limited to 600°C, 620°C, 640°C, 660°C, 680°C, 700°C, 720°C, 740°C, 760°C, 780°C, 800°C or a range between any two of the above temperatures.

[0162] The technical scheme of the present invention is described in detail below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods for which specific conditions are not specified in the following embodiments are preferably referred to the guidance given in the present invention, and can also be carried out according to the experimental manual or conventional conditions in the art, or according to the conditions recommended by the manufacturer, or with reference to experimental methods known in the art.

[0163] Example 1

[0164] S1: The size is 10×10×5mm 3 The SiC ceramic is used as the matrix, and the SiC ceramic matrix is ​​pretreated by sandblasting. The sandblasting pressure is 5 MPa and the sandblasting time is 120 seconds.

[0165] S2: The Si bonding layer is prepared on the surface of the pretreated SiC ceramic substrate by atmospheric plasma spraying, and the spray powder is filled as the spray path program and spray parameters are set, and the gun is fired. The particle size D50 of the Si powder used for spraying is 47μm, the spraying current is 600A, the spray gun power is 36KW, the argon flow rate is 40slpm, the hydrogen flow rate is 6slpm, the powder feeding rate is 30g / min, the spraying distance is 100mm, and the thickness of the Si bonding layer is 100μm.

[0166] S3: The intermediate layer was prepared on the surface of the bonding layer by atmospheric plasma spraying. The spraying powder used was ytterbium disilicate (YbDS), the powder particle size D50 was 325 μm, the spraying current was 600 A, the spray gun power was 40 kW, the argon flow rate was 40 slpm, the hydrogen flow rate was 10 slpm, the powder feeding rate was 30 g / min, the spraying distance was 100 mm, and the intermediate layer thickness was about 120 μm.

[0167] S4: Use CAD software to draw a grid-like periodic structure and import it into the UV laser control software. The overall size of the periodic structure is consistent with the upper surface area of ​​the environmental barrier intermediate layer. Place the sample on the laser processing platform, and adjust the position of the processing platform so that the laser spot is focused on the surface of the environmental barrier intermediate layer. The diameter of the laser spot after focusing is about 15μm.

[0168] S5: Set the processing parameters of the laser to process the environmental barrier intermediate layer, where the laser pulse width is 10ns, the laser power is 4W, the repetition frequency is 10kHz, the scanning speed is 100mm / s, and the scanning repetition number is 4 times; the surface of the sample after processing is as follows Figure 2 As shown in (a), the grid etching depth of laser processing is about 30μm, and the spacing of the etched areas is 100μm.

[0169] S6: Place the laser-etched SiC-based ceramic sample with the bonding layer and the environmental barrier intermediate layer in a fixture, and then fix the fixture to the sample stage of the plasma physical vapor deposition equipment and set the deposition control program; fill the powder feeder with (Gd 0.3 Yb 0.7 )2Zr2O7 powder; close the equipment cabin, check the equipment sealing and then evacuate, when the vacuum degree reaches below 0.1mbar, fill with argon to 130mbar; light the gun to start the arc, wait for the arc to stabilize, evacuate to below 3mbar, start the control program, move the sample stage to a position 1000mm away from the spray gun, and adjust the spray gun to face the sample; gradually increase the spray gun current to 1800A, set the helium flow rate to 40slpm, the argon flow rate to 20slpm, and the spray power to 60k W, and use plasma jet to preheat the sample to 800℃; heat the temperature in the powder feeder cabin to 60℃, open the powder feeding gas line, adjust the powder feeding carrier gas flow rate to 8slpm, spray time to 20min, and deposit coating thickness to about 100μm; close the powder feeding gas line, gradually reduce the spray gun current and plasma gas flow rate, fill with argon to 60mbar, turn off the gun, extinguish the arc, turn off the vacuum pump after cooling for 20min, take out the sample after the cabin is balanced with the atmospheric pressure, and obtain the environmental barrier-infrared stealth coating.

[0170] Example 2

[0171] The preparation method of Example 2 is similar to that of Example 1, except that: in step S5 of Example 2, the laser power is 6 W, the repetition frequency is 30 kHz, the scanning speed is 50 mm / s, and the number of scanning repetitions is 2 times; the cross section of the sample after processing is as follows: Figure 2 As shown in (b), the grid etching depth of laser processing is about 40μm, and the spacing of the etched areas is 50μm.

[0172] Example 3

[0173] The preparation method of Example 3 is similar to that of Example 1, except that in step S5 of Example 3, the laser power is 10 W, the repetition frequency is 20 kHz, the scanning speed is 200 mm / s, and the number of scanning repetitions is 5 times.

[0174] Example 4

[0175] The preparation method of Example 4 is similar to that of Example 1, except that in step S2 of Example 4, the spraying current is 700A, the spray gun power is 40KW, the argon flow rate is 30slpm, the hydrogen flow rate is 8slpm, the powder feeding rate is 35g / min, and the spraying distance is 80mm.

[0176] Example 5

[0177] The preparation method of Example 5 is similar to that of Example 1, except that in step S2 of Example 5, the spraying current is 500A, the spray gun power is 35KW, the argon flow rate is 35slpm, the hydrogen flow rate is 5slpm, the powder feeding rate is 25g / min, and the spraying distance is 90mm.

[0178] Example 6

[0179] The preparation method of Example 6 is similar to that of Example 1, except that in step S3 of Example 6, the spraying current is 600A, the spray gun power is 45KW, the argon flow rate is 30slpm, the hydrogen flow rate is 12slpm, the powder feeding rate is 35g / min, and the spraying distance is 80mm.

[0180] Example 7

[0181] The preparation method of Example 7 is similar to that of Example 1, except that in step S3 of Example 7, the spraying current is 650A, the spray gun power is 42KW, the argon flow rate is 35slpm, the hydrogen flow rate is 10slpm, the powder feeding rate is 25g / min, and the spraying distance is 90mm.

[0182] Example 8

[0183] The preparation method of Example 8 is similar to that of Example 1, except that: in step S6 of Example 8, the vacuum is evacuated to 3 mbar, the sample stage is moved to a position 1200 mm away from the spray gun, the spray gun current is 1950 A, the helium flow rate is set to 40 slpm, the argon flow rate is 20 slpm, the spraying power is 65 kW, and the sample is preheated to 800°C using a plasma jet.

[0184] Example 9

[0185] The preparation method of Example 9 is similar to that of Example 1, except that: in step S6 of Example 9, the vacuum is evacuated to 1 mbar, the sample stage is moved to a position 800 mm away from the spray gun, the spray gun current is 1900 A, the helium flow rate is set to 40 slpm, the argon flow rate is 20 slpm, the spraying power is 62 kW, and the sample is preheated to 800°C using a plasma jet.

[0186] Comparative Example 1

[0187] The preparation method of Comparative Example 1 is similar to that of Example 1, except that: in Comparative Example 1, there is no step S4 and step S5, the intermediate layer is not etched, and there is no etched area on the surface of the intermediate layer. Figure 2 As shown in (c).

[0188] Comparative Example 2

[0189] The preparation method of Comparative Example 2 is similar to that of Example 1, except that: in Comparative Example 2, there is no step S4, step S5 and step S6, the intermediate layer is not etched, there is no etching area on the surface of the intermediate layer, and no infrared stealth layer is prepared.

[0190] Comparative Example 3

[0191] The size is 10×10×5mm 3 SiC ceramics is used as Comparative Example 3.

[0192] The structural parameters of the above-mentioned embodiments 1-9 and comparative example 1 are shown in Table 1.

[0193] Table 1

[0194]

[0195] The above embodiments and comparative examples were tested for performance, and the results are shown in Table 2. The infrared emissivity of Embodiment 1, Embodiment 2, Comparative Example 1 and Comparative Example 3 (SiC) in the 3μm~5μm band at different temperatures is shown in Table 2. Figure 3 As shown, Figure 3 (a) is 800°C, (b) is 1100°C. The test conditions or test standards for each performance test item are as follows:

[0196] (1) Water vapor corrosion life test: A water vapor corrosion test was conducted at 1100°C using a mixture of water vapor and oxygen in a volume ratio of 9:1. The flow rate of the mixed gas was 1 slpm, and the mass change of the sample after 300 hours of corrosion was evaluated.

[0197] (2) Thermal insulation effect test: The thermal insulation effect of the coating was tested according to Q / AVIC06018-2013 "Test method for thermal insulation effect of thermal barrier coatings". The experimental temperature was 1100°C, the cooling gas flow rate was (40±0.5) m / s, the cooling gas temperature was (500±5)°C, the temperature difference between the inner and outer walls was calculated, and the thermal insulation effect of the sample was obtained by comparison with the blank sample.

[0198] (3) Infrared emissivity test: The sample was heated to 800°C and 1100°C respectively, and the hemispherical infrared radiation intensity of the sample and the standard black body in the range of 3 to 5 μm was tested under the same conditions to obtain the infrared emissivity.

[0199] Table 2

[0200]

[0201] From the comparison of the results of Examples 1-9 and Comparative Examples 1-3 in Table 2, it can be seen that compared with Comparative Examples 1-3, the environmental barrier-infrared stealth coating in Examples 1-9 has lower thermal conductivity and infrared emissivity, and has better anti-water vapor corrosion effect; indicating that the environmental barrier-infrared stealth coating provided by the present application has excellent high-temperature corrosion resistance and infrared stealth performance. The reason for this is that: in the environmental barrier-infrared stealth coating provided by the present application, the bonding layer can be rapidly oxidized under high-temperature service conditions to generate a protective SiO2 oxide film to prevent the SiC-based ceramic substrate from being corroded; the middle layer has a dense structure, which can inhibit the contact and reaction of high-temperature water vapor with the SiO2 oxide film, reduce the generation and volatilization rate of Si(OH)4, and the combined action of the bonding layer and the middle layer can avoid the performance degradation of the SiC-based ceramic substrate. On the one hand, the infrared stealth layer can achieve diffraction extinction of its own infrared radiation through the columnar cavity and reduce the infrared emissivity. On the other hand, it can achieve heat insulation through low thermal conductivity ceramic columnar crystals and ceramic particles to reduce the surface temperature. The two work together to reduce the infrared radiation intensity of the components and achieve infrared stealth.

[0202] In addition, by Figure 2 It can be seen that the intermediate layer of Example 1 and Example 2 has an etched structure, such as Figure 2 (a) and Figure 2 As shown in (b), the top infrared stealth layer is composed of ceramic columnar crystals, ceramic particles gathered in the etched area, and columnar cavities above the ceramic particles, forming an environmental barrier-infrared stealth coating with a micro-nano composite structure. Figure 2 As shown in (c), the top layer is composed of densely arranged ceramic columnar crystals and ceramic particles distributed in the gaps between the ceramic columnar crystals, and there are no columnar cavities.

[0203] Depend on Figure 3 It can be seen that at 800℃ ( Figure 3 (a)) and 1100℃ ( Figure 3 In (b), in the wavelength range of 3~5μm, the emissivity of pure silicon carbide (Comparative Example 3) is significantly higher than that of other samples with coatings, while the infrared emissivity of the samples of Example 1 and Example 2 with micro-nano composite structures is significantly lower than that of Comparative Example 1.

[0204] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0205] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An environmental barrier-infrared stealth coating, characterized in that: It includes a SiC-based ceramic substrate, an adhesive layer, an intermediate layer and an infrared stealth layer which are stacked in sequence; at least one etching area is arranged on the surface of the intermediate layer on one side relatively adjacent to the infrared stealth layer; the infrared stealth layer contains ceramic columnar crystals, ceramic particles and a columnar cavity between two adjacent ceramic columnar crystals; the ceramic particles are filled in the etching area; the ceramic columnar crystals are located in the unetched area of ​​the surface of the intermediate layer having the etching area; and the columnar cavity is located above the ceramic particles.

2. The environmental barrier-infrared stealth coating according to claim 1, characterized in that: The infrared stealth layer has at least one of the following characteristics (1)-(4): (1) The material of the infrared stealth layer includes one or more of rare earth zirconates and rare earth hafnates; (2) The width of the ceramic columnar crystal is 10 μm-40 μm; (3) The thickness of the infrared stealth layer is 100 μm-150 μm; (4) The average particle size of the ceramic particles is 0.5 μm-10 μm; (5) The volume proportion of the ceramic columnar crystals in the infrared stealth layer is 40%-80%; (6) The volume proportion of the ceramic particles in the infrared stealth layer is 5%-30%; (7) The volume proportion of the columnar cavity in the infrared stealth layer is 10%-40%; (8) The columnar cavity penetrates the infrared stealth layer along the thickness direction of the infrared stealth layer, and the width of the columnar cavity is 8 μm-15 μm.

3. The environmental barrier-infrared stealth coating according to claim 1, characterized in that: The intermediate layer has at least one of the following features (1)-(4): (1) The depth of the etching area is 5 μm-50 μm, the width of the etching area is 10 μm-30 μm, and the distance between two adjacent etching areas is 20 μm-200 μm; (2) The thickness of the intermediate layer is 80 μm-150 μm; (3) The material of the intermediate layer includes one or both of ytterbium silicate and ytterbium disilicate; (4) The porosity of the intermediate layer is less than 10%.

4. The environmental barrier-infrared stealth coating according to any one of claims 1 to 3, characterized in that: The bonding layer has at least one of the following features (1)-(2): (1) The thickness of the adhesive layer is 60 μm-125 μm; (2) The material of the adhesive layer includes Si.

5. The environmental barrier-infrared stealth coating according to any one of claims 1 to 3, characterized in that: The SiC-based ceramic matrix is ​​selected from a silicon carbide matrix or a silicon carbide fiber reinforced silicon carbide ceramic-based composite material matrix.

6. A method for preparing an environmental barrier-infrared stealth coating, characterized in that: The steps include: Performing sandblasting pretreatment on at least one side surface of the SiC-based ceramic substrate; forming an adhesive layer on the surface of the SiC-based ceramic substrate after sandblasting pretreatment, and forming an intermediate layer on the surface of the adhesive layer relatively away from the SiC-based ceramic substrate; Performing an etching process on the intermediate layer to form at least one etching area on a surface of the intermediate layer relatively far from the bonding layer; An infrared stealth layer is formed on the surface of the intermediate layer having the etching area, and the infrared stealth layer comprises ceramic columnar crystals, ceramic particles and a columnar cavity between two adjacent ceramic columnar crystals, the ceramic particles are filled in the etching area, the ceramic columnar crystals are located in the unetched area of ​​the surface of the intermediate layer having the etching area, and the columnar cavity is located above the ceramic particles.

7. The preparation method according to claim 6, characterized in that: The preparation method of the bonding layer includes atmospheric plasma spraying.

8. The preparation method according to claim 7, characterized in that: The method for preparing the bonding layer comprises at least one of the following conditions (1)-(6): (1) The spraying current of the atmospheric plasma spraying is 500A-700A; (2) The spraying power of the atmospheric plasma spraying is 35KW-40KW; (3) The gas used in the atmospheric plasma spraying includes argon gas, and the argon gas flow rate is 30slpm-40slpm; (4) The gas used in the atmospheric plasma spraying includes hydrogen, and the hydrogen flow rate is 5slpm-8slpm; (5) The powder feeding rate of the atmospheric plasma spraying is 25g / min-35g / min; (6) The spraying distance of the atmospheric plasma spraying is 80 mm-100 mm.

9. The preparation method according to claim 6, characterized in that: The preparation method of the intermediate layer includes atmospheric plasma spraying.

10. The preparation method according to claim 9, characterized in that: The method for preparing the intermediate layer includes at least one of the following conditions (1)-(6): (1) The spraying current of the atmospheric plasma spraying is 500A-700A; (2) The spraying power of the atmospheric plasma spraying is 40KW-45KW; (3) The gas used in the atmospheric plasma spraying includes argon gas, and the argon gas flow rate is 30slpm-40slpm; (4) The gas used in the atmospheric plasma spraying includes hydrogen, and the hydrogen flow rate is 8slpm-12slpm; (5) The powder feeding rate of the atmospheric plasma spraying is 25g / min-35g / min; (6) The spraying distance of the atmospheric plasma spraying is 80 mm-100 mm.

11. The preparation method according to claim 6, characterized in that: The preparation method of the intermediate layer includes plasma physical vapor deposition.

12. The preparation method according to claim 11, characterized in that: The method for preparing the intermediate layer includes at least one of the following conditions (1)-(5): (1) The deposition current of the plasma physical vapor deposition is 1100A-1200A; (2) The deposition power of the plasma physical vapor deposition is 30KW-40KW; (3) The plasma gas used in the plasma physical vapor deposition includes argon and helium, the argon flow rate is 20slpm-40slpm, and the helium flow rate is 30slpm-60slpm; (4) The powder feeding rate of the plasma physical vapor deposition is 8g / min-10g / min; (5) The spraying distance of the plasma physical vapor deposition is 600mm-800mm.

13. The preparation method according to claim 6, characterized in that: The intermediate layer is etched by using a pulse laser.

14. The preparation method according to claim 13, characterized in that: The etching process includes at least one of the following conditions (1)-(7): (1) The laser center wavelength of the pulsed laser is 355 nm; (2) The laser focus spot diameter of the pulse laser is 10 μm-20 μm; (3) The pulse width of the pulse laser is 10ns-20ns; (4) The laser power of the pulsed laser is 3W-10W; (5) The repetition frequency of the pulsed laser is 10kHz-30kHz; (6) The scanning speed of the pulse laser is 50 mm / s-200 mm / s; (7) The scanning repetition number of the pulse laser is 1 to 5 times.

15. The preparation method according to any one of claims 6 to 14, characterized in that: The preparation method of the infrared stealth layer includes plasma physical vapor deposition.

16. The preparation method according to claim 15, characterized in that: The method for preparing the infrared stealth layer includes at least one of the following conditions (1)-(7): (1) The vacuum degree of the plasma physical vapor deposition is 1 mbar-5 mbar; (2) The working gas used in the plasma physical vapor deposition includes argon and helium, the argon flow rate is 20slpm-40slpm, and the helium flow rate is 30slpm-60slpm; (3) The spray gun distance of the plasma physical vapor deposition is 800mm-1200mm; (4) The deposition current of the plasma physical vapor deposition is 1800A-2100A; (5) The deposition power of the plasma physical vapor deposition is 55kW-65kW; (6) The powder feeding rate of the plasma physical vapor deposition is 8g / min-10g / min; (7) The sample preheating temperature of the plasma physical vapor deposition is 600°C-800°C.

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