An antioxidant composite coating with an in-situ diffusion barrier layer and its preparation and application

Abstract

The present invention relates to the technical field of thermal barrier coatings, and in particular to an antioxidant composite coating with an in-situ diffusion barrier layer, and its preparation and application. The antioxidant composite coating with an in-situ diffusion barrier layer of the present invention is composed of a NiAlHf-NiCoCrAlY composite bonding layer formed by NiAlHf, NiCoCrAlY and nano-alumina particles, located on the surface of a substrate, nano-alumina particles in-situ dispersed in the NiAlHf-NiCoCrAlY composite bonding layer, and an alumina diffusion barrier layer in-situ formed at the NiAlHf-NiCoCrAlY composite bonding layer-substrate interface. The antioxidant composite coating with an in-situ diffusion barrier layer provided by the present invention has stronger high-temperature oxidation resistance and diffusion resistance, and its temperature bearing capacity can reach 1200°C. It can be used as a metal bonding layer of an ultra-high temperature thermal barrier coating, thereby increasing the service life of the thermal barrier coating and reducing the damage of the metal bonding layer to the mechanical properties of the hot end components of the high-temperature alloy.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal barrier coatings, in particular to an anti-oxidation composite coating with an in-situ diffusion barrier layer and the preparation and application thereof. Background Art

[0002] Thermal barrier coatings (TBCs) are key materials and technologies for advanced aircraft engines, significantly increasing the operating temperature of hot-end components (such as turbine blades) and boosting engine efficiency. The metallic bond layer plays a crucial role in thermal barrier coatings, not only protecting high-temperature alloy components from oxidation but also enhancing interfacial bonding. Therefore, it is the core layer of a TBC, directly determining its service life. Currently, the most commonly used bond layer materials are NiAlHf and NiCoCrAlY. NiAlHf bond layers offer excellent oxidation resistance, but are also highly brittle and prone to cracking during service. NiCoCrAlY bond layers offer excellent mechanical properties, but lack sufficient oxidation resistance. Furthermore, both bond layers exhibit significant interdiffusion with the high-temperature alloy substrate, significantly compromising the coating's compositional stability and the substrate's mechanical properties. These defects in bond layers limit their service temperature to 1100°C, making them incapable of meeting the application temperature requirements of next-generation aircraft engine TBCs. Previous methods of modifying with trace elements or preparing additional diffusion-resistant layers only address a single issue at the expense of other properties, failing to fundamentally address the current bond layer deficiencies. Therefore, the key to developing a bonding layer that can withstand temperatures exceeding 1100°C lies in achieving a synergistic improvement in antioxidant properties, mechanical properties, and interfacial diffusion resistance. Summary of the Invention

[0003] In order to solve the above problems, the purpose of the present invention is to provide an antioxidant composite coating with an in-situ diffusion barrier layer and its preparation and application. The antioxidant composite coating with an in-situ diffusion barrier layer of the present invention is composed of a NiAlHf-NiCoCrAlY composite bonding layer formed by NiAlHf, NiCoCrAlY and nano-alumina particles, located on the surface of the substrate, nano-alumina particles in situ dispersed in the NiAlHf-NiCoCrAlY composite bonding layer, and an alumina diffusion barrier layer in situ formed at the interface of the NiAlHf-NiCoCrAlY composite bonding layer-substrate. The antioxidant composite coating with an in-situ diffusion barrier layer provided by the present invention has stronger high-temperature oxidation resistance and diffusion resistance, and its temperature bearing capacity can reach 1200°C. It can be used as a metal bonding layer of an ultra-high temperature thermal barrier coating, thereby increasing the service life of the thermal barrier coating and reducing the damage of the metal bonding layer to the mechanical properties of the hot end components of the high-temperature alloy.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] The first object of the present invention is to provide an oxidation-resistant composite coating having an in-situ diffusion barrier layer, comprising a NiAlHf-NiCoCrAlY composite bonding layer formed by NiAlHf, NiCoCrAlY and nano-alumina particles and located on the surface of a substrate, nano-alumina particles in-situ dispersed in the NiAlHf-NiCoCrAlY composite bonding layer, and an alumina diffusion barrier layer in-situ formed at the interface of the NiAlHf-NiCoCrAlY composite bonding layer and the substrate.

[0006] In one embodiment of the present invention, the thickness of the anti-oxidation composite coating with the in-situ diffusion barrier layer is 150 μm-300 μm.

[0007] In one embodiment of the present invention, in the oxidation-resistant composite coating with the in-situ diffusion barrier layer, the volume fraction of NiAlHf is 45-55%, the volume fraction of NiCoCrAlY is 35-55%, and the volume fraction of nano-alumina particles is 5-20%.

[0008] In one embodiment of the present invention, the size of the nano-alumina is less than 100 nanometers.

[0009] In one embodiment of the present invention, the aluminum oxide diffusion barrier layer comprises α-Al 2 O 3 and has a thickness of 1 μm to 5 μm.

[0010] A second object of the present invention is to provide a method for preparing an anti-oxidation composite coating having an in-situ diffusion barrier layer, comprising the following steps:

[0011] The mixed powder obtained by mixing NiAlHf powder and NiCoCrAlY powder is sprayed onto the surface of the substrate by active combustion high velocity gas spraying, and then subjected to high temperature heat treatment to obtain an antioxidant composite coating with an in-situ diffusion barrier layer.

[0012] In one embodiment of the present invention, the particle size of the NiAlHf powder is 1 μm to 10 μm;

[0013] The mass ratio of NiAlHf powder to NiCoCrAlY powder is 2:3 to 3:2.

[0014] In one embodiment of the present invention, NiAlHf powder is obtained by crushing NiAlHf blocks into particle sizes of 3 mm to 5 mm and then using wet planetary ball milling; during the wet planetary ball milling process, the ball milling medium is anhydrous ethanol, the ball-to-material ratio is 5:1, the ball milling speed is 400 rpm, and the ball milling time is 5 hours. During the ball milling process, the milling is stopped for 30 minutes every hour to prevent the temperature from being too high.

[0015] In one embodiment of the present invention, NiAlHf powder and NiCoCrAlY powder are mixed to obtain a powder by dry planetary spheroidal graphite. During the dry planetary spheroidal graphite process, the ball-to-material ratio is 10:1, the ball milling speed is 200 rpm, and the ball milling time is 10 h. During the ball milling process per hour, the milling is stopped for 30 minutes to prevent the temperature from being too high.

[0016] In one embodiment of the present invention, the particle size of the NiAlHf powder is 1 μm to 10 μm, and the particle size of the NiCoCrAlY powder is 30 μm to 85 μm.

[0017] In one embodiment of the present invention, during the active combustion high-speed fuel gas spraying process, the propane pressure is 70PSI~80PSI, the air pressure is 80PSI~90PSI, the nitrogen flow rate is 20L / min~25L / min, the powder feeding speed is 2L / min-5L / min, the spray gun moving speed is 1000mm / s~2000mm / s, and the spraying distance is 150mm~200mm.

[0018] In one embodiment of the present invention, the high temperature heat treatment includes a first stage and a second stage;

[0019] In the first stage, the temperature is 1000°C, the holding time is 24h~48h, and the heating rate is 5°C / min;

[0020] In the first stage, the temperature is 1100°C, the holding time is 5h-10h, and the cooling rate is 5°C / min;

[0021] The processing atmosphere was high-purity argon gas with a gas flow rate of 500 mL / min.

[0022] The third object of the present invention is to provide a substrate having a surface covered with an anti-oxidation composite coating having an in-situ diffusion barrier layer.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention obtains NiAlHf powder with a particle size of 1 μm to 10 μm by wet grinding, and mixes it with NiCoCrAlY powder by dry grinding to obtain a mixed powder; further, the mixed powder is used as a raw material, and the powder is sprayed onto the surface of a nickel-based high-temperature alloy using an active combustion high-velocity gas spraying technology, and combined with high-temperature heat treatment, an antioxidant composite coating with an in-situ diffusion barrier layer is obtained.

[0025] (2) The NiAlHf-NiCoCrAlY composite bonding layer in the anti-oxidation composite coating with an in-situ diffusion barrier layer of the present invention can combine the advantages of the two bonding layers, so that the anti-oxidation performance and mechanical properties of the composite bonding layer are basically guaranteed.

[0026] (3) The in-situ dispersion strengthening of nano-alumina particles in the antioxidant composite coating with an in-situ diffusion barrier layer of the present invention can further improve the mechanical properties of the composite bonding layer, and can reduce the thermal expansion coefficient of the composite bonding layer, reduce the thermal stress in the oxide film, and further improve the antioxidant performance of the bonding layer.

[0027] (4) The aluminum oxide interfacial diffusion barrier layer in the oxidation-resistant composite coating with an in-situ diffusion barrier layer of the present invention can inhibit the mutual diffusion of elements between the NiAlHf-NiCoCrAlY composite bonding layer and the high-temperature alloy substrate, thereby ensuring the composition stability of the NiAlHf-NiCoCrAlY composite bonding layer and reducing damage to the mechanical properties of the high-temperature alloy substrate.

[0028] In summary, the antioxidant composite coating with an in-situ diffusion barrier provided by the present invention can achieve synergistic improvements in antioxidant performance, mechanical properties, and interfacial diffusion barrier performance, thereby improving the temperature bearing capacity of the NiAlHf-NiCoCrAlY composite bonding layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 These are cross-sectional scanning electron micrographs of the anti-oxidation composite coating with an in-situ diffusion barrier layer prepared in Example 1; (a) is a low-magnification cross-sectional scanning electron micrograph; (b) is a partial enlarged view of the interior of the NiAlHf-NiCoCrAlY composite bonding layer; and (c) is a partial enlarged view of the interface between the NiAlHf-NiCoCrAlY composite bonding layer and the substrate.

[0030] Figure 2 This is a cross-sectional scanning electron microscope photograph of the anti-oxidation composite coating with an in-situ diffusion barrier layer prepared in Example 1 after being oxidized at 1200° C. for 100 hours. DETAILED DESCRIPTION

[0031] The present invention provides an oxidation-resistant composite coating with an in-situ diffusion barrier layer, comprising a NiAlHf-NiCoCrAlY composite bonding layer formed by NiAlHf, NiCoCrAlY and nano-alumina particles and located on the surface of a substrate, nano-alumina particles in-situ dispersed in the NiAlHf-NiCoCrAlY composite bonding layer, and an alumina diffusion barrier layer in-situ formed at the interface between the NiAlHf-NiCoCrAlY composite bonding layer and the substrate.

[0032] In one embodiment of the present invention, the thickness of the anti-oxidation composite coating with the in-situ diffusion barrier layer is 150 μm-300 μm.

[0033] In one embodiment of the present invention, in the oxidation-resistant composite coating with the in-situ diffusion barrier layer, the volume fraction of NiAlHf is 45-55%, the volume fraction of NiCoCrAlY is 35-55%, and the volume fraction of nano-alumina particles is 5-20%.

[0034] In one embodiment of the present invention, the size of the nano-alumina is less than 100 nanometers.

[0035] In one embodiment of the present invention, the aluminum oxide diffusion barrier layer comprises α-Al 2 O 3 and has a thickness of 1 μm to 5 μm.

[0036] The present invention provides a method for preparing an anti-oxidation composite coating having an in-situ diffusion barrier layer, comprising the following steps:

[0037] The mixed powder obtained by mixing NiAlHf powder and NiCoCrAlY powder is sprayed onto the surface of the substrate by active combustion high velocity gas spraying, and then subjected to high temperature heat treatment to obtain an antioxidant composite coating with an in-situ diffusion barrier layer.

[0038] In one embodiment of the present invention, the particle size of the NiAlHf powder is 1 μm to 10 μm;

[0039] The mass ratio of NiAlHf powder to NiCoCrAlY powder is 2:3 to 3:2.

[0040] In one embodiment of the present invention, NiAlHf powder is obtained by crushing NiAlHf blocks into particle sizes of 3 mm to 5 mm and then using wet planetary ball milling; during the wet planetary ball milling process, the ball milling medium is anhydrous ethanol, the ball-to-material ratio is 5:1, the ball milling speed is 400 rpm, and the ball milling time is 5 hours. During the ball milling process, the milling is stopped for 30 minutes every hour to prevent the temperature from being too high.

[0041] In one embodiment of the present invention, NiAlHf powder and NiCoCrAlY powder are mixed to obtain a powder by dry planetary spheroidal graphite. During the dry planetary spheroidal graphite process, the ball-to-material ratio is 10:1, the ball milling speed is 200 rpm, and the ball milling time is 10 h. During the ball milling process per hour, the milling is stopped for 30 minutes to prevent the temperature from being too high.

[0042] In one embodiment of the present invention, the particle size of the NiAlHf powder is 1 μm to 10 μm, and the particle size of the NiCoCrAlY powder is 30 μm to 85 μm.

[0043] In one embodiment of the present invention, during the active combustion high-speed fuel gas spraying process, the propane pressure is 70PSI~80PSI, the air pressure is 80PSI~90PSI, the nitrogen flow rate is 20L / min~25L / min, the powder feeding speed is 2L / min-5L / min, the spray gun moving speed is 1000mm / s~2000mm / s, and the spraying distance is 150mm~200mm.

[0044] In one embodiment of the present invention, the high temperature heat treatment includes a first stage and a second stage;

[0045] In the first stage, the temperature is 1000°C, the holding time is 24h~48h, and the heating rate is 5°C / min;

[0046] In the first stage, the temperature is 1100°C, the holding time is 5h-10h, and the cooling rate is 5°C / min;

[0047] The processing atmosphere was high-purity argon gas with a gas flow rate of 500 mL / min.

[0048] The invention provides a substrate whose surface is covered with an anti-oxidation composite coating having an in-situ diffusion barrier layer.

[0049] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] In the following examples, unless otherwise specified, all reagents used are commercially available reagents, and all detection means and methods used are conventional detection means and methods in the art.

[0051] Example 1

[0052] This embodiment provides an anti-oxidation composite coating having an in-situ diffusion barrier layer and a preparation method thereof.

[0053] (1) The NiAlHf block was crushed to a particle size of 3 mm to 5 mm, and the crushed product was placed in a 500 ml stainless steel ball mill, and then stainless steel balls and anhydrous ethanol were added; the sealed stainless steel vacuum ball mill was fixed on a planetary ball mill for wet planetary ball milling; the speed of the planetary ball mill was 400 rpm, the ball milling time was 5 h, and the mass ratio of balls: ethanol: powder (the above crushed product) was 10:1:1; and during the ball milling process, the milling was stopped for 30 minutes every hour to prevent the temperature from being too high; after the ball milling was completed, the powder was dried in an oven (the oven temperature was 100 ° C, and the drying time was 24 h) to obtain NiAlHf powder with a particle size of 1 μm to 10 μm.

[0054] (2) The NiAlHf powder and NiCoCrAlY powder (mass ratio of 3:2) prepared in step (1) are placed in a 500 ml stainless steel ball mill, and the sealed stainless steel vacuum ball mill is fixed on a planetary ball mill for ball milling; the mass ratio of ball to mixed powder is 10:1; the rotation speed of the planetary ball mill is 200 rpm, the ball milling time is 10 h, and during the ball milling process, the ball mill is stopped for 30 minutes every hour to prevent the temperature from being too high, to obtain a mixed powder.

[0055] (3) spraying the mixed powder prepared in step (2) onto the surface of the nickel-based high-temperature alloy by active combustion high-velocity gas spraying, and combining it with a subsequent high-temperature heat treatment to obtain an anti-oxidation composite coating with an in-situ diffusion barrier layer having a thickness of 200 μm;

[0056] During the active combustion high-speed fuel gas spraying process, the propane pressure is 80PSI; the air pressure is 90PSI; the nitrogen flow rate is 25L / min; the powder feeding speed is 5L / min; the spray gun moving speed is 2000mm / s; and the spraying distance is 200mm.

[0057] High temperature heat treatment includes the first and second stages:

[0058] The first stage: temperature 1000℃, holding time 48h, heating rate 5℃ / min;

[0059] The second stage: continue heating to 1100℃, keep warm for 10h, and cool down at a rate of 5℃ / min;

[0060] The processing atmosphere was high-purity argon with a gas flow rate of 500 mL / min.

[0061] Characterization and performance analysis:

[0062] The microstructure of the anti-oxidation composite coating with in-situ diffusion barrier layer prepared in this embodiment was characterized by scanning electron microscopy. Figure 1 As shown. The composite bonding layer is mainly composed of a composite structure of NiAlHf and NiCoCrAlY ( Figure 1 a), nano-alumina particles are dispersed in situ in the bonding layer ( Figure 1 b), and an aluminum oxide interface diffusion barrier layer is in situ grown at the interface between the bonding layer and the nickel-based high-temperature alloy ( Figure 1 c) In the oxidation-resistant composite coating with an in-situ diffusion barrier layer prepared in this embodiment, the volume fractions of NiAlHf, NiCoCrAlY, and nano-alumina particles were approximately 55%, 37%, and 18%, respectively. The thickness of the alumina interface diffusion barrier layer was approximately 2 microns. These results demonstrate that the method of this embodiment is capable of preparing an oxidation-resistant composite coating with an in-situ diffusion barrier layer.

[0063] The anti-oxidation composite coating with an in-situ diffusion barrier layer obtained in this example was placed in a high-temperature box furnace for oxidation resistance testing. The temperature was maintained at 1200°C in an air atmosphere for 100 hours, and then air-cooled to room temperature within 20 minutes. The microstructure of the anti-oxidation composite coating with an in-situ diffusion barrier layer after oxidation was characterized using a scanning electron microscope ( Figure 2 ).Depend on Figure 2 It can be seen that a uniform and continuous Al2O3 protective film is formed on the surface of the anti-oxidation composite coating with an in-situ diffusion barrier layer, and no cracks are found. In addition, the alumina interface diffusion barrier layer completely blocks the mutual diffusion of high-temperature elements between the composite bonding layer and the nickel-based high-temperature alloy. This indicates that the anti-oxidation composite coating with an in-situ diffusion barrier layer prepared in this embodiment has a temperature resistance of 1200°C and has excellent antioxidant, mechanical and diffusion barrier properties, and can meet the application temperature requirements of the next generation of ultra-high temperature thermal barrier coatings.

[0064] Example 2

[0065] This embodiment provides an anti-oxidation composite coating having an in-situ diffusion barrier layer and a preparation method thereof.

[0066] (1) The NiAlHf block was crushed to a particle size of 3 mm to 5 mm, and the crushed product was placed in a 500 ml stainless steel ball mill, and then stainless steel balls and anhydrous ethanol were added; the sealed stainless steel vacuum ball mill was fixed on a planetary ball mill for wet planetary ball milling; the rotation speed of the planetary ball mill was 400 rpm, the ball milling time was 5 h, and the mass ratio of balls: ethanol: powder was 10:1:1; and during the ball milling process, the milling was stopped for 30 minutes every hour to prevent the temperature from being too high; after the ball milling was completed, the powder was dried in an oven (the oven temperature was 100 ° C, and the drying time was 24 h) to obtain NiAlHf powder with a particle size of 1 μm to 10 μm.

[0067] (2) The NiAlHf powder and the NiCoCrAlY powder (mass ratio of 1:1) prepared in step (1) are placed in a 500 ml stainless steel ball mill; the sealed stainless steel vacuum ball mill is fixed on a planetary ball mill for ball milling; the mass ratio of balls to mixed powder is 10:1; the rotation speed of the planetary ball mill is 200 rpm, the ball milling time is 10 h, and during the ball milling process, the milling is stopped for 30 minutes every hour to prevent the temperature from being too high; and a mixed powder is obtained.

[0068] (3) spraying the mixed powder prepared in step (2) onto the surface of the nickel-based high-temperature alloy by active combustion high-velocity gas spraying, and combining it with a subsequent high-temperature heat treatment to obtain a nano-alumina particle-dispersed reinforced NiAlHf-NiCoCrAlY composite bonding layer with a thickness of 150 μm and an alumina interface diffusion barrier layer;

[0069] During the active combustion high-speed fuel gas spraying process, the propane pressure is 70PSI; the air pressure is 80PSI; the nitrogen flow rate is 20L / min; the powder feeding speed is 2L / min; the spray gun moving speed is 1000mm / s; and the spraying distance is 150mm.

[0070] High temperature heat treatment includes the first and second stages:

[0071] The first stage: temperature 1000℃, holding time 24h, heating rate 5℃ / min;

[0072] The second stage: continue heating to 1100℃, keep warm for 5h, and cool down at a rate of 5℃ / min;

[0073] The processing atmosphere was high-purity argon with a gas flow rate of 500 mL / min.

[0074] The composite bonding layer prepared in this example primarily consists of a composite structure of NiAlHf and NiCoCrAlY. Nano-alumina particles are dispersed in situ within the composite bonding layer, and an alumina interfacial diffusion barrier layer is grown in situ at the interface between the composite bonding layer and the nickel-based superalloy. The volume fractions of NiAlHf, NiCoCrAlY, and nano-alumina particles in the oxidation-resistant composite coating with an in-situ diffusion barrier layer are approximately 48%, 39%, and 13%, respectively. The thickness of the alumina interfacial diffusion barrier layer is approximately 5 microns.

[0075] Example 3

[0076] This embodiment provides an anti-oxidation composite coating having an in-situ diffusion barrier layer and a preparation method thereof.

[0077] (1) The NiAlHf block was crushed to a particle size of 3 mm to 5 mm, and the crushed product was placed in a 500 ml stainless steel ball mill, followed by the addition of stainless steel balls and anhydrous ethanol; the sealed stainless steel vacuum ball mill was fixed on a planetary ball mill for wet planetary ball milling; the rotation speed of the planetary ball mill was 400 rpm, the ball milling time was 5 h, and the mass ratio of balls: ethanol: powder was 10:1:1; and during the ball milling process, the milling was stopped for 30 minutes every hour to prevent the temperature from being too high; after the ball milling was completed, the powder was dried in an oven (the oven temperature was 100 ° C, and the drying time was 24 h) to obtain NiAlHf powder with a particle size of 1 μm to 10 μm.

[0078] (2) The NiAlHf powder and NiCoCrAlY powder (mass ratio of 2:3) prepared in step (1) are placed in a 500 ml stainless steel ball mill; the sealed stainless steel vacuum ball mill is fixed on a planetary ball mill for ball milling; the mass ratio of balls to mixed powder is 10:1; the rotation speed of the planetary ball mill is 200 rpm, the ball milling time is 10 h, and during the ball milling process, the milling is stopped for 30 minutes every hour to prevent the temperature from being too high, thereby obtaining a mixed powder.

[0079] (3) spraying the mixed powder obtained in step (2) onto the surface of the nickel-based high-temperature alloy by active combustion high-velocity gas spraying, and combining it with a subsequent high-temperature heat treatment to obtain an anti-oxidation composite coating with an in-situ diffusion barrier layer having a thickness of 300 μm;

[0080] During the active combustion high-speed fuel gas spraying process, the propane pressure is 75PSI; the air pressure is 85PSI; the nitrogen flow rate is 22L / min; the powder feeding speed is 3L / min; the spray gun moving speed is 1500mm / s; and the spraying distance is 180mm.

[0081] The high temperature heat treatment process includes the first stage and the second stage:

[0082] The first stage: temperature 1000℃, holding time 36h, heating rate 5℃ / min;

[0083] In the second stage, the temperature is continued to rise to 1100℃, the holding time is 8h, and the cooling rate is 5℃ / min;

[0084] The processing atmosphere was high-purity argon with a gas flow rate of 500 mL / min.

[0085] The composite bonding layer prepared in this example primarily consists of a composite structure of NiAlHf and NiCoCrAlY. Nano-alumina particles are dispersed in situ within the composite bonding layer, and an alumina interfacial diffusion barrier layer is grown in situ at the interface between the composite bonding layer and the nickel-based superalloy. The volume fractions of NiAlHf, NiCoCrAlY, and nano-alumina particles in the oxidation-resistant composite coating with an in-situ diffusion barrier layer are approximately 41%, 52%, and 7%, respectively. The thickness of the alumina interfacial diffusion barrier layer is approximately 1 micron.

[0086] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the explanations of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. An anti-oxidation composite coating with an in-situ diffusion barrier layer, characterized in that: A NiAlHf-NiCoCrAlY composite bonding layer formed by NiAlHf, NiCoCrAlY and nano-alumina particles on the substrate surface, nano-alumina particles in-situ dispersed in the NiAlHf-NiCoCrAlY composite bonding layer, and an alumina diffusion barrier layer in-situ formed at the interface of the NiAlHf-NiCoCrAlY composite bonding layer and the substrate; The anti-oxidation composite coating with an in-situ diffusion barrier layer is prepared by the following method: The mixed powder obtained by mixing NiAlHf powder and NiCoCrAlY powder is sprayed onto the surface of the substrate by active combustion high velocity gas spraying, and then subjected to high temperature heat treatment to obtain an antioxidant composite coating with an in-situ diffusion barrier layer.

2. The anti-oxidation composite coating with an in-situ diffusion barrier layer according to claim 1, characterized in that: The thickness of the anti-oxidation composite coating with the in-situ diffusion barrier layer is 150 μm-300 μm.

3. The anti-oxidation composite coating with an in-situ diffusion barrier layer according to claim 1, characterized in that: In the oxidation-resistant composite coating with the in-situ diffusion barrier layer, the volume fraction of NiAlHf is 45-55%, the volume fraction of NiCoCrAlY is 35-55%, and the volume fraction of nano-alumina particles is 5-20%.

4. The anti-oxidation composite coating with an in-situ diffusion barrier layer according to claim 1, characterized in that: The size of the nano-aluminum oxide is less than 100 nanometers.

5. The anti-oxidation composite coating with an in-situ diffusion barrier layer according to claim 1, characterized in that: The composition of the alumina diffusion barrier layer is α-Al2O3, and the thickness is 1μm~5μm.

6. A method for preparing an antioxidant composite coating having an in-situ diffusion barrier layer according to any one of claims 1 to 5, characterized in that: The following steps are involved: The mixed powder obtained by mixing NiAlHf powder and NiCoCrAlY powder is sprayed onto the surface of the substrate by active combustion high velocity gas spraying, and then subjected to high temperature heat treatment to obtain an antioxidant composite coating with an in-situ diffusion barrier layer.

7. The method for preparing an anti-oxidation composite coating having an in-situ diffusion barrier layer according to claim 6, characterized in that: The particle size of NiAlHf powder is 1μm~10μm; The mass ratio of NiAlHf powder to NiCoCrAlY powder is 2:3~3:

2.

8. The method for preparing an anti-oxidation composite coating having an in-situ diffusion barrier layer according to claim 6, characterized in that: During the active combustion high-speed fuel gas spraying process, the propane pressure is 70PSI~80PSI, the air pressure is 80PSI~90PSI, the nitrogen flow rate is 20L / min~25L / min, the powder feeding speed is 2L / min-5L / min, the spray gun moving speed is 1000mm / s~2000mm / s, and the spraying distance is 150mm~200mm.

9. The method for preparing an anti-oxidation composite coating having an in-situ diffusion barrier layer according to claim 6, characterized in that: High temperature heat treatment includes the first and second stages; In the first stage, the temperature is 1000°C, the holding time is 24h~48h, and the heating rate is 5°C / min; In the first stage, the temperature is 1100°C, the holding time is 5h~10h, and the cooling rate is 5°C / min; The processing atmosphere was high-purity argon gas with a gas flow rate of 500 mL / min.

10. A substrate having a surface covered with the anti-oxidation composite coating having an in-situ diffusion barrier layer according to any one of claims 1 to 5.

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