Infrared stealth coating, preparation method and application thereof

Abstract

This invention belongs to the field of functional coatings, specifically disclosing an infrared stealth coating, its preparation method, and its application. The coating comprises a first ceramic layer, a second ceramic layer, and a modified layer stacked sequentially. The first ceramic layer is made of yttrium-stabilized zirconium oxide. The second ceramic layer is made of zirconium oxide and at least two oxides selected from yttrium oxide, gadolinium oxide, ytterbium oxide, cerium oxide, thulium oxide, and neodymium oxide doped in the zirconium oxide. The modified layer contains Ti, Al, or an AlTi alloy. The coating of this invention, by introducing a modified layer to encapsulate the ceramic layer, exhibits high bonding strength between the ceramic layer and the modified layer, exceeding 70 MPa, and possesses excellent thermal insulation performance and low infrared emissivity. Specifically, the coating's thermal conductivity from room temperature to 1500℃ is <1 W / m·K, and its infrared emissivity under atmospheric conditions is ≤0.55.

Description

Technical Field

[0001] This invention belongs to the field of functional coating technology, and specifically relates to an infrared stealth coating, its preparation method, and its application. Background Technology

[0002] Infrared stealth coatings refer to the application of materials with low infrared emissivity under atmospheric windows (8-14μm band) to the surface of components in the form of coatings or thin films, giving them low infrared detection capabilities. They have important applications in military technology, and their design and preparation are indispensable key technologies for national defense weapons and equipment.

[0003] As infrared stealth coatings have evolved, simply maintaining low infrared emission is no longer sufficient to meet the increasingly stringent high-temperature / ultra-high-temperature service requirements of aerospace equipment. Boltzmann's law defines infrared radiation intensity. Where ε represents the material emissivity, σ is the Boltzmann constant, and T is the material thermodynamic temperature, then to reduce the infrared radiation intensity of the material, it is necessary to reduce both the infrared emissivity and the surface temperature. Traditional infrared stealth coatings with low infrared emissivity generally have high thermal conductivity and poor heat insulation performance, resulting in high surface temperatures and inability to operate stably at 1150℃. Reducing surface infrared emissivity cannot simultaneously control surface temperature. According to the Boltzmann equation, the overall infrared radiation intensity cannot be optimally controlled. Therefore, there is an urgent need to develop high-temperature / ultra-high-temperature infrared stealth coatings with low infrared emissivity and high heat insulation performance. Summary of the Invention

[0004] In order to overcome at least one of the technical problems existing in the prior art, one of the objectives of the present invention is to provide a coating.

[0005] The second objective of this invention is to provide a method for preparing a coating.

[0006] The third objective of this invention is to provide a product.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A first aspect of the present invention provides a coating comprising a first ceramic layer, a second ceramic layer, and a modified layer disposed sequentially.

[0009] The material of the first ceramic layer includes yttrium oxide-stabilized zirconium oxide;

[0010] The material of the second ceramic layer includes zirconium oxide and at least two oxides selected from yttrium oxide, gadolinium oxide, ytterbium oxide, cerium oxide, thulium oxide, and neodymium oxide doped in the zirconium oxide;

[0011] The modified layer contains Ti, Al, or an AlTi alloy.

[0012] In this invention, the first and second ceramic layers are feather-like columnar structures with high thermal insulation and low thermal conductivity. A modified layer with low infrared emissivity covers the top of the feather-like columnar ceramic layers (i.e., the first and second ceramic layers). The coating with the above structure exhibits good stability and thermal insulation performance at ultra-high temperatures of 1400℃. The modified layer and feather-like columnar ceramic layers covering the top can improve the scattering of infrared light by the coating at atmospheric windows, and the modified layer covering the top of the feather-like columnar ceramic layers can improve the back reflection of infrared light by the coating at atmospheric windows, thereby reducing the overall infrared emissivity of the coating. The coating of this invention has an infrared emissivity of no more than 0.55 within an 8-14μm atmospheric window while maintaining good thermal barrier performance. It is suitable for infrared stealth protection of hot-end components of aero-engines, significantly improving the thermal stealth and service life of equipment.

[0013] In some embodiments of the present invention, the coating further includes an adhesive layer located on the side of the first ceramic layer opposite to the second ceramic layer.

[0014] In some embodiments of the present invention, the mass percentage of yttrium oxide in the first ceramic layer is 5-10%, and the mass percentage of zirconium oxide is 90-95%.

[0015] In some embodiments of the present invention, the mass percentage of yttrium oxide in the first ceramic layer can be any value of 5%, 6%, 7%, 8%, 9%, 10%, or a range formed by any two of these values.

[0016] In some embodiments of the present invention, the mass percentage of zirconium oxide in the first ceramic layer is any one of 90%, 91%, 92%, 93%, 94%, 95%, or a range formed by any two of these values.

[0017] In some embodiments of the present invention, in the second ceramic layer, the mass percentage of each of at least two oxides selected from yttrium oxide, gadolinium oxide, ytterbium oxide, cerium oxide, thulium oxide, and neodymium oxide is 1-10%, with zirconium oxide as the balance.

[0018] In some embodiments of the present invention, the second ceramic layer contains 3-10% yttrium oxide, 3-10% gadolinium oxide, 3-10% ytterbium oxide, and 70-91% zirconium oxide by mass.

[0019] In some embodiments of the present invention, the mass percentage of yttrium oxide in the second ceramic layer is any one of 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a range formed by any two of these values.

[0020] In some embodiments of the present invention, the mass percentage of gadolinium oxide in the second ceramic layer is any one of 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a range formed by any two of these values.

[0021] In some embodiments of the present invention, the mass percentage of ytterbium oxide in the second ceramic layer is any one of 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a range formed by any two of these values.

[0022] In some embodiments of the present invention, the mass percentage of zirconium oxide in the second ceramic layer is any one of 70%, 73%, 75%, 76%, 78%, 80%, 82%, 84%, 85%, 86%, 88%, 90%, 91%, or a range formed by any two of these values.

[0023] In some embodiments of the present invention, the mass percentage of Ti in the AlTi alloy is 5-50%, and the mass percentage of Al is 50-95%.

[0024] In some embodiments of the present invention, the mass percentage of Ti in the AlTi alloy is any value or a range formed by any two of the following: 5%, 7%, 10%, 13%, 15%, 17%, 20%, 23%, 25%, 27%, 30%, 33%, 35%, 37%, 40%, 43%, 45%, 47%, 50%.

[0025] In some embodiments of the present invention, the mass percentage of Al in the AlTi alloy is any value or a range formed by any two of 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, and 95%.

[0026] In some embodiments of the present invention, the thickness of the modified layer is 1-100 μm; in some embodiments of the present invention, the thickness of the modified layer is any value or a range formed by any two of the following: 1 μm, 3 μm, 5 μm, 7 μm, 10 μm, 13 μm, 15 μm, 17 μm, 20 μm, 23 μm, 25 μm, 27 μm, 30 μm, 33 μm, 35 μm, 37 μm, 40 μm, 43 μm, 45 μm, 47 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm; in some embodiments of the present invention, the thickness of the modified layer is 1-50 μm.

[0027] In some embodiments of the present invention, the thickness of the first ceramic layer is 10-500 μm; in some embodiments of the present invention, the thickness of the first ceramic layer is any value or a range formed by any two of 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, and 500 μm.

[0028] In some embodiments of the present invention, the thickness of the second ceramic layer is 10-500 μm; in some embodiments of the present invention, the thickness of the second ceramic layer is any value or a range formed by any two of 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, and 500 μm.

[0029] In some embodiments of the present invention, the modified layer further contains TiAlZrO3; the presence of TiAlZrO3 in the modified layer gives it low infrared emissivity, excellent thermal stability and corrosion resistance, and significantly improves the high-temperature infrared stealth performance of the coating.

[0030] In some embodiments of the present invention, the structure formed by the stacking of the first ceramic layer and the second ceramic layer is feather-like. The stacking of the first ceramic layer and the second ceramic layer to form a feather-like structure achieves phase structure stability at 1500°C, and the thermal conductivity from room temperature to 1500°C is <1W / m·K, which can significantly improve the stable service temperature of the infrared stealth coating and reduce the surface temperature of the material, thereby reducing the infrared radiation intensity.

[0031] A second aspect of the present invention provides a method for preparing the coating described in the first aspect of the present invention, comprising the following steps:

[0032] S1: A first ceramic layer and a second ceramic layer are sequentially prepared on the surface of a substrate; or, an adhesive layer, a first ceramic layer, and a second ceramic layer are sequentially prepared on the surface of a substrate.

[0033] S2: Prepare a modified layer on the second ceramic layer, and then heat treat it to obtain the coating;

[0034] The first ceramic layer, the second ceramic layer, and the adhesive layer are respectively prepared by plasma spraying-physical vapor deposition or low-pressure plasma deposition.

[0035] The modified layer is prepared by vacuum arc ion plating or magnetron sputtering.

[0036] The coating preparation method of this invention uses plasma spraying-physical vapor deposition or low-pressure plasma deposition to prepare a first ceramic layer with a feather columnar structure and a second ceramic layer to obtain a composite ceramic layer. A low infrared emission modification layer is prepared by vacuum arc ion plating or magnetron sputtering. By adjusting the process parameters, a dense bond between the modification layer and the composite ceramic layer (i.e., the first ceramic layer and the second ceramic layer) is achieved, ensuring that the coating does not undergo phase change or peel off under ultra-high temperature conditions.

[0037] This invention uses vacuum arc ion plating or magnetron sputtering to form a modified layer on a second ceramic layer in situ. Because it is generated in situ, the modified layer will not fall off due to stress accumulation inside the coating caused by interface factors. Furthermore, since the modified layer and the surface of the second ceramic layer are chemically bonded, the overall bonding performance of the coating will not be reduced. As a result, the bonding strength between the second ceramic layer and the modified layer is greater than 70 MPa, which is suitable for infrared stealth requirements of key hot-end components such as aero-engines under high or ultra-high temperature conditions.

[0038] In some embodiments of the present invention, the heat treatment is performed in a vacuum heat treatment furnace.

[0039] In some embodiments of the present invention, the temperature of the heat treatment is 400-1100°C; in some embodiments of the present invention, the temperature of the heat treatment is any value or a range formed by any two of 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, and 1100°C.

[0040] In some embodiments of the present invention, the heat treatment time is 1-10 hours; in some embodiments of the present invention, the heat treatment time is any value of 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, or a range formed by any two of these values.

[0041] In some embodiments of the present invention, the heating rate of the heat treatment is 150-200℃ / h; in some embodiments of the present invention, the heating rate of the heat treatment is any value of 150℃ / h, 160℃ / h, 170℃ / h, 180℃ / h, 190℃ / h, 200℃ / h, or a range formed by any two of these values.

[0042] In some embodiments of the present invention, the heat treatment is performed under a vacuum or protective atmosphere.

[0043] In some embodiments of the present invention, the protective atmosphere refers to an inert atmosphere formed by at least one of nitrogen, argon, and helium.

[0044] When the modified layer in this invention is heat-treated under vacuum or a protective atmosphere, it reacts and generates TiAlZrO3 with low infrared emissivity and excellent high-temperature stability. This completely coats the surface of the feather-like columnar crystals (i.e., the composite structure of the first and second ceramic layers) and forms a modified layer with low infrared emissivity. During service, the ultra-high temperature coating of the feather-like columnar crystals formed by the stacking of the first and second ceramic layers maintains phase structure stability at 1500℃, achieving a thermal conductivity of <1W / m·K from room temperature to 1500℃. This enables high thermal insulation and stable service at ultra-high temperatures, reducing infrared radiation intensity by lowering the surface temperature. The low infrared emissivity and high-temperature stability of the modified TiAlZrO3 layer further reduce infrared radiation intensity. The preparation method in this invention can improve the integrity and uniformity of the modified layer coating on the surface of the feather-like columnar crystals, significantly improving infrared stealth performance.

[0045] In some embodiments of the present invention, the substrate needs to be sandblasted before use.

[0046] In some embodiments of the present invention, the sandblasting pressure is 0.3-0.4 MPa.

[0047] In some embodiments of the present invention, the sandblasting angle is 50°-70°.

[0048] In some embodiments of the present invention, the sandblasting time is 1-5 minutes.

[0049] In some embodiments of the present invention, the sandblasting is performed using zirconium corundum as the sandblasting material.

[0050] In some embodiments of the present invention, the substrate is ultrasonically cleaned before sandblasting.

[0051] In some embodiments of the present invention, the ultrasonic cleaning is performed using alcohol and / or acetone as the cleaning solution.

[0052] In some embodiments of the present invention, at least one of the following parameters is used when preparing the adhesive layer using the plasma spraying-physical vapor deposition method:

[0053] (a1) NiCoCrAlY was used as the spraying material during preparation;

[0054] (a2) The spraying distance is 300-500mm;

[0055] (a3) The bonding layer is applied under a vacuum of 5-100 mbar, an argon flow rate of 50-200 L / min, and a hydrogen flow rate of 1-10 L / min;

[0056] (a4) Spraying current 1000-2000A.

[0057] In some embodiments of the present invention, before the first ceramic layer is prepared on the adhesive layer, the adhesive layer needs to be ground and polished to make the surface roughness of the adhesive layer 1-5 μm.

[0058] In some embodiments of the present invention, in NiCoCrAlY, the mass percentage of Co is 20-25%, the mass percentage of Cr is 15-20%, the mass percentage of Al is 10-15%, the mass percentage of Y is 0.1-1%, and Ni is the balance.

[0059] In some embodiments of the present invention, the thickness of the adhesive layer is 10-300 μm.

[0060] In some embodiments of the present invention, at least one of the following parameters is used when preparing the first ceramic layer using the plasma spraying-physical vapor deposition method:

[0061] (b1) Yttrium-stabilized zirconium oxide was used as the raw material in the preparation process;

[0062] (b2) The spraying distance is 500-1200mm;

[0063] (b3) The first ceramic layer is formed under a vacuum of 5-100 mbar, an argon flow rate of 5-50 L / min, a helium flow rate of 10-100 L / min, and a hydrogen flow rate of 1-10 L / min;

[0064] (b4) Spraying current 1500-3000A;

[0065] (b5) Spraying power 100-150kW.

[0066] In some embodiments of the present invention, when the first ceramic layer is prepared by the plasma spraying-physical vapor deposition method, the spraying distance is any value of 500mm, 600mm, 700mm, 800mm, 900mm, 1000mm, 1100mm, 1200mm or a range formed by any two of them.

[0067] In some embodiments of the present invention, when the first ceramic layer is prepared using the plasma spraying-physical vapor deposition method, the spraying current is any value of 1500A, 1600A, 1800A, 2000A, 2200A, 2400A, 2500A, 2600A, 2800A, 3000A, or a range formed by any two of these values.

[0068] In some embodiments of the present invention, when the first ceramic layer is prepared using the plasma spraying-physical vapor deposition method, the spraying power is any value of 100 kW, 110 kW, 120 kW, 130 kW, 140 kW, 150 kW, or a range formed by any two of these values.

[0069] In some embodiments of the present invention, at least one of the following parameters is used when preparing the second ceramic layer using the plasma spraying-physical vapor deposition method:

[0070] (c1) Spraying distance is 500-1200mm;

[0071] (c2) The second ceramic layer is formed under a vacuum of 5-100 mbar, an argon flow rate of 5-50 L / min, a helium flow rate of 10-100 L / min, and a hydrogen flow rate of 1-10 L / min;

[0072] (c3) Spraying current 1500-3000A;

[0073] (c4) Spraying power 100-150kW.

[0074] In some embodiments of the present invention, when the second ceramic layer is prepared by the plasma spraying-physical vapor deposition method, the spraying distance is any value of 500mm, 600mm, 700mm, 800mm, 900mm, 1000mm, 1100mm, 1200mm or a range formed by any two of these values.

[0075] In some embodiments of the present invention, when the second ceramic layer is prepared using the plasma spraying-physical vapor deposition method, the spraying current is any value of 1500A, 1600A, 1800A, 2000A, 2200A, 2400A, 2500A, 2600A, 2800A, 3000A, or a range formed by any two of these values.

[0076] In some embodiments of the present invention, when the second ceramic layer is prepared using the plasma spraying-physical vapor deposition method, the spraying power is any value of 100 kW, 110 kW, 120 kW, 130 kW, 140 kW, 150 kW, or a range formed by any two of these values.

[0077] In some embodiments of the present invention, the second ceramic layer needs to be cleaned before preparing the modified layer. In some embodiments of the present invention, the second ceramic layer is brushed with ethanol and / or acetone and then dried with nitrogen gas before preparing the modified layer.

[0078] In some embodiments of the present invention, at least one of the following parameters is used when preparing the modified layer using the vacuum arc ion plating method:

[0079] (d1) The material used to prepare the modified layer is used as the target material;

[0080] (d2) Temperature is 150-350℃;

[0081] (d3) Bias voltage is 80-180V;

[0082] (d4) The current is 50-150A;

[0083] (d5) The flow rate of the protective gas is 18-28 sccm.

[0084] In some embodiments of the present invention, when the modified layer is prepared by the vacuum arc ion plating method, the temperature can be any value or a range formed by any two of the following: 150°C, 160°C, 180°C, 200°C, 220°C, 240°C, 250°C, 260°C, 280°C, 300°C, 320°C, 340°C, and 350°C.

[0085] In some embodiments of the present invention, when the modified layer is prepared by the vacuum arc ion plating method, the bias voltage can be any value or a range formed by any two of 80V, 90V, 100V, 110V, 120V, 130V, 140V, 150V, 160V, 170V, and 180V.

[0086] In some embodiments of the present invention, when the modified layer is prepared by the vacuum arc ion plating method, the current can be any value of 50A, 60A, 70A, 80A, 90A, 100A, 110A, 120A, 130A, 140A, 150A, or a range of any two.

[0087] In some embodiments of the present invention, when the modified layer is prepared by the vacuum arc ion plating method, the flow rate of the protective gas can be any value of 18 sccm, 20 sccm, 22 sccm, 24 sccm, 26 sccm, 28 sccm or a range formed by any two of them.

[0088] In some embodiments of the present invention, at least one of the following parameters is used when preparing the modified layer using the magnetron sputtering method:

[0089] (e1) Use the material for preparing the modified layer as the target material;

[0090] (e2) Temperature is 150-350℃;

[0091] (e3) Bias voltage is 60-140V;

[0092] (e4) The flow rate of the protective gas is 140-180 sccm;

[0093] (e5) Vacuum degree is 4×10 -3 Pa -6×10 -3 Pa.

[0094] In some embodiments of the present invention, the target material may be selected from at least one of Ti target, Al target, and Al-Ti alloy target.

[0095] In some embodiments of the present invention, the purity of the target material is ≥99.99%.

[0096] In some embodiments of the present invention, when the modified layer is prepared by the magnetron sputtering method, the temperature can be any value or a range formed by any two of 150°C, 160°C, 180°C, 200°C, 220°C, 240°C, 250°C, 260°C, 280°C, 300°C, 320°C, 340°C, and 350°C.

[0097] In some embodiments of the present invention, when the modified layer is prepared by the magnetron sputtering method, the bias voltage can be any value of 60V, 70V, 80V, 90V, 100V, 110V, 120V, 130V, 140V or a range formed by any two of them.

[0098] In some embodiments of the present invention, when the modified layer is prepared by the magnetron sputtering method, the flow rate of the protective atmosphere is any value of 140 sccm, 150 sccm, 160 sccm, 170 sccm, 180 sccm, or a range formed by any two of them.

[0099] In some embodiments of the present invention, when the modified layer is prepared using the magnetron sputtering method, the vacuum degree is 4 × 10⁻⁶. -3 Pa, 4.5 × 10 -3 Pa, 5×10 -3 Pa, 5.5 × 10 -3 Pa, 6×10 -3 Any value in Pa, or a range of values ​​formed by any two of them.

[0100] In some embodiments of the present invention, target refining is required before the modified layer is prepared using the magnetron sputtering method.

[0101] In some embodiments of the present invention, the target refining step has at least one of the following parameters:

[0102] (f1) The temperature during target refining is 300-400℃;

[0103] (f2) The vacuum level during target refining is 4×10⁻⁶. -2 Pa -6×10 -2 Pa;

[0104] (f3) The bias voltage during target refining is 400-600V;

[0105] (f4) The magnetic bias voltage during target refining is 7-9V and the magnetic field frequency is 8-9Hz.

[0106] A third aspect of the invention provides a product comprising the coating described in the first aspect of the invention; the product includes aircraft equipment, marine equipment, or fighter jets.

[0107] In some embodiments of the present invention, the aviation equipment includes an engine.

[0108] In some embodiments of the present invention, the aviation equipment includes an aircraft or flying vehicle.

[0109] In some embodiments of the present invention, the product is selected from the surface skin of an aircraft engine or a high-speed aircraft.

[0110] The beneficial effects of the present invention are: the coating of the present invention covers the ceramic layer (i.e., the first ceramic layer and the second ceramic layer) by introducing a modified layer, the bonding strength between the ceramic layer and the modified layer is high, reaching more than 70MPa, and has excellent heat insulation performance and low infrared emissivity, specifically: the thermal conductivity of the coating from room temperature to 1500℃ is <1W / m·K, and the infrared emissivity of the coating under the atmospheric window is ≤0.55.

[0111] This invention utilizes the feather-like columnar ceramic layer structure formed by the stacking of the first and second ceramic layers to maintain phase structure stability at ultra-high temperatures of 1500℃, thereby achieving a thermal conductivity of <1W / m·K from room temperature to 1500℃, realizing high thermal insulation and stable service at ultra-high temperatures, and reducing infrared radiation intensity by lowering the surface temperature; and utilizing the low infrared emissivity and high-temperature stability of TiAlZrO3 in the modified layer to reduce infrared radiation intensity. Attached Figure Description

[0112] Figure 1 The image shows a cross-sectional SEM image (scale bar is 200 μm) of the infrared stealth coating in Example 1.

[0113] Figure 2 The image shows a cross-sectional SEM image (scale bar is 10 μm) of the infrared stealth coating in Example 1.

[0114] Figure 3 The image shows the XRD pattern of the infrared stealth coating in Example 1.

[0115] Figure 4 This is a graph showing the infrared emissivity of the infrared stealth coating in Example 1.

[0116] Figure 5 The image shows the infrared emissivity test results of the ultra-high temperature ceramic coating prepared in Comparative Example 1.

[0117] Figure 6 The image shows the infrared emissivity test results of the high-temperature ceramic coating prepared in Comparative Example 2.

[0118] Figure 7 This is a photograph of the infrared stealth coating in Example 1 after its antioxidant performance was tested at 1400°C. Detailed Implementation

[0119] The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described in detail below are those that can be implemented or understood by those skilled in the art by referring to the prior art. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0120] This invention utilizes a plasma spraying-physical vapor deposition (PS-PVD) process to prepare a unique feather-like columnar coating (i.e., a structure formed by stacking a first YSZ ceramic layer and a second GYYZO ceramic layer). This coating enhances thermal radiation scattering through multiphase depositional units, resulting in lower thermal conductivity and higher thermal insulation performance. The PS-PVD process can prepare this unique feather-like columnar coating, which is a gas-liquid-solid multiphase deposition with nanoscale depositional units, thus exhibiting strong interfacial scattering of thermal radiation. Unlike traditional YSZ materials (yttrium-stabilized zirconia), GYYZO materials rely on multi-source rare-earth co-doping to introduce oxygen vacancies. On one hand, this stabilizes the low thermal conductivity tetragonal zirconia at 1500℃; on the other hand, the introduced oxygen vacancies act as strong mass and stress field scattering centers, significantly enhancing the scattering of thermal radiation and reducing thermal conductivity, thereby exhibiting excellent phase stability and thermal insulation at ultra-high temperatures of 1500℃.

[0121] The in-situ reaction of the feather-shaped thermal barrier coating involves generating an intermediate through magnetron sputtering deposition and then synthesizing an AlTi modified layer in situ at the tip of the feather-shaped column under vacuum heat treatment. This technique achieves strong bonding with the ceramic layers without compromising the high strain tolerance of the feather-shaped columnar structure. Furthermore, the in-situ reaction of Al, Ti, and ZrO2 under vacuum heat treatment synthesizes a modified TiAlZrO3 layer with excellent thermal stability and low infrared emissivity, thereby reducing infrared radiation intensity.

[0122] In view of this, the inventors, through long-term research, creatively proposed to synthesize a material with low infrared emissivity and excellent high-temperature stability in situ on the surface of a feather-shaped high-insulation ultra-high temperature coating. This material reduces the surface temperature by lowering the surface infrared emissivity, increasing infrared radiation back reflection, and improving thermal radiation scattering insulation, thereby synergistically reducing the infrared radiation intensity. It also has excellent high-temperature stability and maintains low thermal conductivity even at ultra-high temperatures.

[0123] The specific implementation of the present invention will be further described in detail below with reference to specific embodiments and comparative examples:

[0124] The raw material information used in the embodiments and comparative examples of this invention is as follows:

[0125] In YSZ powder, the mass percentage of Y2O3 is 7%, and the mass percentage of zirconium oxide is 93%.

[0126] The GYYZO powder contains 5% by mass of Gd2O3, Yb2O3, and Y2O3, and 85% by mass of zirconium oxide.

[0127] In NiCoCrAlY powder, the mass percentage of Co is 23%, the mass percentage of Cr is 17%, the mass percentage of Al is 12%, the mass percentage of Y is 0.5%, and the mass percentage of Ni is 47.5%.

[0128] The AlTi target contains 10% Ti by mass and 90% Al by mass.

[0129] Example 1

[0130] This example provides a method for preparing a low thermal conductivity ultra-high temperature infrared stealth coating, including the following steps:

[0131] Step 1: Preparation of ultra-high temperature double ceramic layer by plasma spraying-physical vapor deposition (PS-PVD)

[0132] (1) Select NiCoCrAlY powder, YSZ powder and GYYZO powder with a purity greater than 99.9% and dry them for later use.

[0133] (2) Use alcohol and acetone to ultrasonically clean the substrate material to be sprayed for 5 minutes. Use #46 zirconium corundum (i.e., zirconium corundum with a mesh size of 46) to sandblast and activate the surface to be sprayed. The sandblasting pressure is 0.35 MPa, the sandblasting angle is 60°, and the sandblasting time is 3 minutes.

[0134] (3) A bonding layer (i.e., NiCoCrAlY layer) was prepared on the surface of the substrate material by low-pressure plasma spraying. The coating thickness was 100μm and the material used was NiCoCrAlY powder. The spraying was carried out at a distance of 400mm, a chamber pressure of 15mbar, an argon flow rate of 70L / min, a hydrogen flow rate of 2L / min, and a spraying current of 1500A to obtain the bonding layer. The obtained bonding layer was then polished to make the surface roughness of the bonding layer 4μm.

[0135] (4) A YSZ ceramic layer was prepared on the surface of the polished adhesive layer by plasma spraying-physical vapor deposition, with a coating thickness of 150 μm. The material used was YSZ powder, the spraying distance was 1100 mm, the chamber pressure was 5 mbar vacuum, the argon flow rate was 40 L / min, the helium flow rate was 80 L / min, the hydrogen flow rate was 2 L / min, the spraying current was 2400 A, and the spraying power was 120 kW.

[0136] (5) A GYYZO ceramic layer was prepared on the surface of the YSZ ceramic layer by plasma spraying-physical vapor deposition, with a coating thickness of 150 μm. The material used was GYYZO powder, the spraying distance was 1100 mm, the chamber pressure was 5 mbar vacuum, the argon flow rate was 45 L / min, the helium flow rate was 90 L / min, the hydrogen flow rate was 2 L / min, the spraying current was 2800 A, and the spraying power was 130 kW.

[0137] Step 2: Modified layer magnetron sputtering vacuum coating

[0138] (1) The surface of the GYYZO ceramic layer obtained by plasma spraying-physical vapor deposition (PS-PVD) is cleaned by brushing with ethanol or acetone and then drying with nitrogen.

[0139] (2) Install the AlTi target required for coating in the magnetron sputtering equipment. Set the parameters: temperature 350℃, vacuum degree 5×10 -2 Pa, start heating, evacuate, introduce argon gas and turn on the bias voltage, set the bias voltage to 500V, adjust the magnetron bias voltage to 8.0V, and the magnetic field frequency to 8.3Hz to carry out target refining.

[0140] (3) Place the cleaned coated sample (i.e., the sample with YSZ / GYYZO coating obtained after step (1) in step two) into the magnetron sputtering equipment, evacuate, and set the parameters: 300℃, vacuum degree 5×10 -3 Pa, turntable speed 5.0 rpm, start heating, evacuate, purge argon gas, argon gas flow rate 150 sccm, apply bias point target to AlTi target (the mass percentage of Ti in AlTi target is 10% and the mass percentage of Al is 90%), set voltage 70V, coating time 400min.

[0141] (5) After the coating is completed, release the gas until the pressure is balanced, then open the door and take out the sample.

[0142] Step 3: Vacuum heat treatment of the modified layer

[0143] The sample obtained in step two was placed in a vacuum heat treatment furnace, and the heat treatment curve was set to a vacuum level below 2.0 × 10⁻⁶. - 2 The low thermal conductivity ultra-high temperature infrared stealth coating in this example was prepared by heating to 1000℃ within 360 min and holding at that temperature for 120 min under Pa conditions. The coating thickness was 410-420 μm.

[0144] Comparative Example 1

[0145] This example provides a method for preparing an ultra-high temperature ceramic coating, including the following steps:

[0146] Step 1: Plasma Spraying-Physical Vapor Deposition (PS-PVD) Ultra-High Temperature Double Ceramic Layer

[0147] (1) Select NiCoCrAlY powder, YSZ powder and GYYZO powder with a purity greater than 99.9% and dry them for later use.

[0148] (2) Use alcohol and acetone to ultrasonically clean the substrate material to be sprayed for 5 minutes, and use #46 zirconium corundum to activate the surface to be sprayed. The sandblasting pressure is 0.35 MPa, the sandblasting angle is 60°, and the sandblasting time is 3 minutes.

[0149] (3) A bonding layer was prepared on the surface of the substrate material by low-pressure plasma spraying with a coating thickness of 100 μm. The raw material used was NiCoCrAlY powder. The spraying was carried out at a distance of 400 mm, a chamber pressure of 15 mbar, an argon flow rate of 70 L / min, a hydrogen flow rate of 2 L / min, and a spraying current of 1500 A. The surface roughness of the bonding layer was reduced to 4 μm by grinding and polishing.

[0150] (4) A YSZ ceramic layer was prepared on the surface of the polished bonding layer by plasma spraying-physical vapor deposition, with a coating thickness of 150 μm. The material used was YSZ powder, the spraying distance was 1100 mm, the chamber pressure was 5 mbar vacuum, the argon flow rate was 40 L / min, the helium flow rate was 80 L / min, the hydrogen flow rate was 2 L / min, the spraying current was 2400 A, and the spraying power was 120 kW.

[0151] (5) A GYYZO ceramic layer was prepared on the surface of the YSZ ceramic layer by plasma spraying-physical vapor deposition, with a coating thickness of 150 μm. The material used was GYYZO powder, the spraying distance was 1100 mm, the chamber pressure was 5 mbar vacuum, the argon flow rate was 45 L / min, the helium flow rate was 90 L / min, the hydrogen flow rate was 2 L / min, the spraying current was 2800 A, and the spraying power was 130 kW. The ultra-high temperature ceramic coating in this example was obtained with a thickness of 400 μm.

[0152] Comparative Example 2

[0153] This example provides a method for preparing a high-temperature ceramic coating, including the following steps:

[0154] Step 1: Plasma Spraying-Physical Vapor Deposition (PS-PVD) High-Temperature Ceramic Layer

[0155] (1) Select NiCoCrAlY powder, YSZ powder and GYYZO powder with a purity greater than 99.9% and dry them for later use.

[0156] (2) Use alcohol and acetone to ultrasonically clean the substrate material to be sprayed for 5 minutes, and use #46 zirconium corundum to activate the surface to be sprayed. The sandblasting pressure is 0.35 MPa, the sandblasting angle is 60°, and the sandblasting time is 3 minutes.

[0157] (3) A bonding layer with a thickness of 100 μm was prepared on the surface of the substrate material by low-pressure plasma spraying using NiCoCrAlY powder as the raw material. The spraying was carried out at a distance of 400 mm, a chamber pressure of 15 mbar, an argon flow rate of 70 L / min, a hydrogen flow rate of 2 L / min, and a spraying current of 1500 A. The bonding layer was then polished to achieve a roughness of 4 μm.

[0158] (4) A YSZ ceramic layer with a thickness of 150 μm was prepared on the surface of the polished adhesive layer by plasma spraying-physical vapor deposition. The material used was YSZ powder, the spraying distance was 1100 mm, the chamber pressure was 5 mbar vacuum, the argon flow rate was 40 L / min, the helium flow rate was 80 L / min, the hydrogen flow rate was 2 L / min, the spraying current was 2400 A, and the spraying power was 120 kW. The high-temperature ceramic coating with a thickness of 250 μm was obtained in this example.

[0159] Comparative Example 3

[0160] This example provides a method for preparing a low infrared emissivity ceramic coating, including the following steps:

[0161] Step 1: Preparation of ceramic layer by plasma spraying-physical vapor deposition (PS-PVD)

[0162] (1) Select NiCoCrAlY powder and YSZ powder with a purity greater than 99.9% and dry them for later use.

[0163] (2) Use alcohol and acetone to ultrasonically clean the substrate material to be sprayed for 5 minutes. Use #46 zirconium corundum (i.e., zirconium corundum with a mesh size of 46) to sandblast and activate the surface to be sprayed. The sandblasting pressure is 0.35 MPa, the sandblasting angle is 60°, and the sandblasting time is 3 minutes.

[0164] (3) A bonding layer (i.e., NiCoCrAlY layer) was prepared on the surface of the substrate material by low-pressure plasma spraying. The coating thickness was 100μm and the material used was NiCoCrAlY powder. The spraying was carried out at a distance of 400mm, a chamber pressure of 15mbar, an argon flow rate of 70L / min, a hydrogen flow rate of 2L / min, and a spraying current of 1500A to obtain the bonding layer. The obtained bonding layer was then polished to make the surface roughness of the bonding layer 4μm.

[0165] (4) A YSZ ceramic layer was prepared on the surface of the polished adhesive layer by plasma spraying-physical vapor deposition, with a coating thickness of 150 μm. The material used was YSZ powder, the spraying distance was 1100 mm, the chamber pressure was 5 mbar vacuum, the argon flow rate was 40 L / min, the helium flow rate was 80 L / min, the hydrogen flow rate was 2 L / min, the spraying current was 2400 A, and the spraying power was 120 kW.

[0166] Step 2: Modified layer magnetron sputtering vacuum coating

[0167] (1) The YSZ ceramic layer obtained by plasma spraying-physical vapor deposition (PS-PVD) is cleaned by brushing with ethanol or acetone and then dried with nitrogen.

[0168] (2) Install the AlTi target required for coating in the magnetron sputtering equipment. Set the parameters: temperature 350℃, vacuum degree 5×10 -2 Pa, start heating, evacuate, introduce argon gas and turn on the bias voltage, set the bias voltage to 500V, adjust the magnetron bias voltage to 8.0V, and the magnetic field frequency to 8.3Hz to carry out target refining.

[0169] (3) Place the cleaned coated sample (i.e., the sample with YSZ coating obtained after step (1) in step two) into the magnetron sputtering equipment, evacuate, and set the parameters: 300℃, vacuum degree 5×10 -3 Pa, turntable speed 5.0 rpm, start heating, evacuate, purge argon gas, argon gas flow rate 150 sccm, apply bias voltage to AlTi target (10% Ti), set voltage 70V, coating time 400min.

[0170] (5) After the coating is completed, release the gas until the pressure is balanced, then open the door and take out the sample.

[0171] Step 3: Vacuum heat treatment of the modified layer

[0172] The sample obtained in step two was placed in a vacuum heat treatment furnace, and the heat treatment curve was set to a vacuum level below 2.0 × 10⁻⁶. - 2 The low thermal conductivity ultra-high temperature infrared stealth coating in this example was prepared by heating to 1000℃ within 360 min and holding at that temperature for 120 min under Pa conditions. The coating thickness was 410-420 μm.

[0173] Performance testing

[0174] The cross-sectional morphology of the infrared stealth coating in Example 1 was tested using a scanning electron microscope, specifically as follows: Figure 1 and Figure 2 As shown, by Figure 1 As can be seen, Example 1 yielded a double ceramic layer with a feather-like columnar structure, the upper half of which is a GYYZO layer and the lower half is a YSZ layer. From Figure 2 It can be seen that the top of the feather columnar crystal is coated with a low infrared emission functional layer, namely the AlTi layer.

[0175] The infrared stealth coating in Example 1 was tested using an X-ray diffractometer. The specific test results are as follows: Figure 3 As shown. The infrared stealth coating prepared in Example 1 contains two phases: t'-ZrO2 and TiAlZrO3.

[0176] The infrared emissivity of the infrared stealth coating in Example 1 was tested according to GJB 5892-2006 "Method for Measurement of Infrared Emissivity". Specifically, as follows... Figure 4 As shown. By Figure 4 It can be seen that the infrared emissivity of the coating is 0.4-0.55 within the 8-14 μm atmospheric window, which is relatively low.

[0177] The infrared emissivity of the ultra-high temperature ceramic coating prepared in Comparative Example 1 was tested, specifically as follows: Figure 5 As shown. By Figure 5 It can be seen that the infrared emissivity of the coating is 0.6-0.8 under the atmospheric window of 8-14 μm. Due to the introduction of oxygen vacancies by multi-element rare earth doping to enhance thermal radiation scattering, its infrared emissivity is reduced, but it is significantly higher than that of the coating prepared in Example 1.

[0178] The infrared emissivity of the ultra-high temperature ceramic coating prepared in Comparative Example 2 was tested, specifically as follows: Figure 6 As shown. By Figure 6It can be seen that the infrared emissivity of the coating is 0.6-0.8 under the atmospheric window of 8-14 μm. Since the PS-PVD multiphase deposition feather columnar structure is grown by the deposition of nano-units, the nano-grain boundaries increase the thermal radiation scattering. Therefore, the infrared emissivity of the YSZ coating prepared in Comparative Example 2 is reduced, but it is significantly higher than that of the coating prepared in Example 1.

[0179] The infrared emissivity of the ceramic coating prepared in Comparative Example 3 was tested. Within an atmospheric window of 8-14 μm, the coating's infrared emissivity was 0.45-0.6. The surface modification layer effectively reduced the infrared emissivity of the feather-like YSZ coating. However, due to the lack of a GYYZO ceramic layer with oxygen vacancies introduced by multi-element rare earth doping to enhance thermal radiation scattering, the infrared emissivity was still higher than that of Example 1 of this invention. Furthermore, in the high-temperature oxidation resistance test, Comparative Example 3 failed due to sintering at 1400℃, failing to meet the performance requirements for ultra-high temperature and low infrared emissivity at 1400℃.

[0180] The high-temperature oxidation resistance test was conducted on Example 1 according to HB 5258-2000 "Test Method for Determination of Oxidation Resistance of Steel and High-Temperature Alloys". The actual product after the test is shown in the figure below. Figure 7 As shown, by Figure 7 It can be seen that the coating in Example 1, after static oxidation at 1400℃ for 100 hours, has an average oxidation rate of <0.1 g / m. 2 •h, reaching the level of complete oxidation resistance, can achieve reliable service at 1400℃.

[0181] The bonding strength of the infrared stealth coating in Example 1 was measured using HB5476-1991 "Test Method for Bond Strength of Thermal Spray Coating". To improve the accuracy of the test, parallel tests were conducted. The average bonding strength was 71.6 MPa, indicating that the infrared stealth coating prepared in Example 1 of this invention has excellent bonding strength.

[0182] The thermal conductivity of the infrared stealth coating prepared in Example 1 from room temperature to 1500℃ was measured according to GB / T 22588-2008 "Measuring thermal diffusivity or thermal conductivity of flash emission". The specific test results are shown in Table 1 below.

[0183] Table 1. Test results of thermal diffusivity and thermal conductivity of the coating in Example 1

[0184]

[0185] As shown in Table 1, the thermal conductivity of the infrared stealth coating in Example 1 is less than 1 W / m·K at temperatures ranging from room temperature to 1500°C, and the thermal diffusivity is 0.22-0.41 m. 2 / s.

[0186] The thermal conductivity of the infrared stealth coating in Comparative Example 1 from room temperature to 1300℃ was measured in accordance with GB / T 22588-2008 "Measurement of thermal diffusivity or thermal conductivity". The specific test results are shown in Table 2.

[0187] Table 2. Test results of thermal diffusivity and thermal conductivity of the coating in Comparative Example 1

[0188]

[0189] As shown in Table 2, the thermal conductivity of the coating in Comparative Example 1 exceeds 1 W / m·K above 1100℃, and its thermal insulation performance is significantly worse than that of Example 1 of the present invention.

[0190] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. An infrared cloaking coating, characterized by: It includes a first ceramic layer, a second ceramic layer, and a modified layer stacked sequentially; The material of the first ceramic layer includes yttrium oxide-stabilized zirconium oxide; The material of the second ceramic layer is composed of zirconium oxide and at least two oxides selected from yttrium oxide, gadolinium oxide, ytterbium oxide, cerium oxide, thulium oxide, and neodymium oxide doped in the zirconium oxide; The modified layer contains an AlTi alloy; The modified layer also contains TiAlZrO3.

2. The infrared cloaking coating of claim 1, wherein: The infrared stealth coating also includes an adhesive layer, which is located on the side of the first ceramic layer opposite to the second ceramic layer.

3. The infrared cloaking coating of claim 1, wherein: In the first ceramic layer, the mass percentage of yttrium oxide is 5-10%, and the mass percentage of zirconium oxide is 90-95%. And / or, in the second ceramic layer, the mass percentage of yttrium oxide is 3-10%, the mass percentage of gadolinium oxide is 3-10%, the mass percentage of ytterbium oxide is 3-10%, and the mass percentage of zirconium oxide is 70-91%; And / or, the mass percentage of Ti in the AlTi alloy is 5-50%, and the mass percentage of Al is 50-95%.

4. The infrared stealth coating according to claim 1, characterized in that: The thickness of the modified layer is 1-100 μm; And / or, the thickness of the first ceramic layer is 10-500 μm; And / or, the thickness of the second ceramic layer is 10-500 μm.

5. The infrared stealth coating according to claim 1, characterized in that: The structure formed by the stacking of the first ceramic layer and the second ceramic layer is feather-shaped.

6. The method for preparing the infrared stealth coating according to any one of claims 1-5, characterized in that: Includes the following steps: S1: A first ceramic layer and a second ceramic layer are sequentially prepared on the surface of a substrate; or, an adhesive layer, a first ceramic layer, and a second ceramic layer are sequentially prepared on the surface of a substrate. S2: Prepare a modified layer on the second ceramic layer, and then heat treat it to obtain the infrared stealth coating; The first ceramic layer, the second ceramic layer, and the adhesive layer are respectively prepared by plasma spraying-physical vapor deposition or low-pressure plasma deposition. The modified layer is prepared by vacuum arc ion plating or magnetron sputtering.

7. The method for preparing the infrared stealth coating according to claim 6, characterized in that: The heat treatment temperature is 400-1100℃; And / or, the heat treatment time is 1-10 hours; And / or, the heating rate of the heat treatment is 150-200℃ / h; And / or, the heat treatment is performed under a vacuum or protective atmosphere.

8. The method for preparing the infrared stealth coating according to claim 6, characterized in that: When preparing the adhesive layer using the plasma spraying-physical vapor deposition method, at least one of the following parameters is used: (a1) NiCoCrAlY was used as the spraying material during preparation; (a2) The spraying distance is 300-500mm; (a3) The bonding layer is applied under a vacuum of 5-100 mbar, an argon flow rate of 50-200 L / min, and a hydrogen flow rate of 1-10 L / min; (a4) Spraying current 1000-2000A; And / or, when preparing the first ceramic layer using the plasma spraying-physical vapor deposition method, at least one of the following parameters is used: (b1) Yttrium-stabilized zirconium oxide was used as the raw material in the preparation process; (b2) The spraying distance is 500-1200mm; (b3) The first ceramic layer is formed under a vacuum of 5-100 mbar, an argon flow rate of 5-50 L / min, a helium flow rate of 10-100 L / min, and a hydrogen flow rate of 1-10 L / min; (b4) Spraying current 1500-3000A; (b5) Spraying power 100-150kW; And / or, when preparing the second ceramic layer using the plasma spraying-physical vapor deposition method, at least one of the following parameters is used: (c1) Spraying distance is 500-1200mm; (c2) The second ceramic layer is formed under a vacuum of 5-100 mbar, an argon flow rate of 5-50 L / min, a helium flow rate of 10-100 L / min, and a hydrogen flow rate of 1-10 L / min; (c3) Spraying current 1500-3000A; (c4) Spraying power 100-150kW.

9. The method for preparing the infrared stealth coating according to claim 6, characterized in that: When preparing the modified layer using the vacuum arc ion plating method, at least one of the following parameters is used: (d1) The material used to prepare the modified layer is used as the target material; (d2) Temperature is 150-350℃; (d3) Bias voltage is 80-180V; (d4) The current is 50-150A; (d5) The flow rate of the protective gas is 18-28 sccm; or, When preparing the modified layer using the magnetron sputtering method, at least one of the following parameters is used: (e1) Use the material for preparing the modified layer as the target material; (e2) Temperature is 150-350℃; (e3) Bias voltage is 60-140V; (e4) The flow rate of the protective gas is 140-180 sccm; (e5) the vacuum degree is 4 x 10 -3 Pa - 6 x 10 -3 Pa.

10. A product containing the infrared stealth coating according to any one of claims 1-5, characterized in that: The products include aviation equipment, marine equipment, or fighter jets.

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