Preparation method of wide-temperature-range wear-resistant high-entropy ceramic coating

Abstract

The invention relates to a preparation method of a wide-temperature-range wear-resistant high-entropy ceramic coating, and belongs to the technical field of ceramic coatings. According to the method, atmospheric plasma spraying is adopted, NiCrCoAlY powder is sprayed to a base body to prepare a bonding layer, then the powder for spraying is sprayed to the bonding layer, and the high-entropy ceramic coating is prepared. According to the method, the high-entropy boride (V0. 2Cr0. 2Ta0. 2Mo0. 2W0. 2) B has the characteristics of high hardness and good thermal stability, and is prepared by adopting an atmospheric plasma spraying technology; the coupling relation among spray granulation parameters, spraying process condition parameters and innovative protective atmosphere application is regulated and controlled through a system, and a (V0. 2Cr0. 2Ta0. 2Mo0. 2W0. 2) B coating is prepared on the surface of a base body in a deposition mode; the coating is compact in structure and has the characteristic of wear resistance in a wide temperature range.

Description

Technical Field

[0001] The invention relates to a method for preparing a wide-temperature-range wear-resistant high-entropy ceramic coating, belonging to the technical field of ceramic coatings. Background Art

[0002] Materials used in aerospace components must have ideal mechanical properties and good damage tolerance to withstand long-term use at temperatures ranging from -30°C to 600°C and radiation exposure. Wear is a continuous tribological phenomenon that significantly affects the service life of mechanical components. As the temperature increases, the mechanical properties of the material degrade and a shear-unstable oxide film may be produced, leading to rapid failure due to wear. Lubricants are commonly used in tribology to minimize friction, wear and flash temperatures to prevent wear failure. However, traditional liquid lubricants degrade at temperatures exceeding 300°C and are clearly unsuitable for use in the aerospace industry. The harmful gases produced by their degradation can have harmful effects on human health and the environment. Therefore, the development of new coatings with excellent wear resistance over a wide temperature range is crucial to the development of the aerospace industry.

[0003] It is generally believed that there is a positive correlation between the hardness of a material and its wear resistance. Previous studies on new high-entropy ceramics have shown that high-entropy monoborides (HEMBs) often have extremely high hardness due to severe lattice distortion that hinders dislocation slip and high valence electron concentration, while transition metals give them high incompressibility. However, current research on high-entropy monoboride materials mainly focuses on preparation and mechanical properties, while research on the preparation of coatings using atmospheric plasma spraying (APS) technology has not been reported. In addition, the deposition mechanism and high-temperature tribological properties of coating materials in scenarios close to actual applications remain unclear.

[0004] Among potential coating technologies, atmospheric plasma spraying is often used to prepare ceramic coatings with high hardness and high melting points due to its high throughput and extremely high plasma jet energy. Although ultra-hard high-entropy boride ceramics have great potential for wear-resistant coating applications, exploring whether the corresponding high-entropy boride coatings can be deposited using atmospheric plasma spraying technology remains a challenge. This is because atmospheric plasma spraying may negatively affect the physical and mechanical properties of high-entropy boride coatings, such as porosity, oxidation, and splash boundaries. Summary of the Invention

[0005] In order to overcome the defects of the prior art, the purpose of the present invention is to provide a method for preparing a high entropy ceramic coating with wide temperature range and wear resistance. 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2)B has the characteristics of high hardness and good thermal stability, and is prepared by atmospheric plasma spraying technology; by systematically regulating the coupling relationship between spray granulation parameters, spraying process parameters and innovative application of protective atmosphere, (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B coating; the coating has a dense structure and is wear-resistant in a wide temperature range.

[0006] To achieve the purpose of the present invention, the following technical solutions are provided.

[0007] A method for preparing a high-entropy ceramic coating that is wear-resistant over a wide temperature range, the method comprising the following steps:

[0008] (1) The clean surface of the substrate to be sprayed is sandblasted to make its surface roughness Ra 5μm to 8μm.

[0009] In step (1):

[0010] The substrate is a metal or alloy, preferably a high-temperature nickel-based alloy.

[0011] A clean substrate surface to be sprayed can be obtained by the following methods:

[0012] The surface of the substrate to be sprayed is cleaned with acetone or ethanol to remove impurities such as dust and oil attached to the surface of the substrate to obtain a clean substrate surface to be sprayed.

[0013] Sand blasting can use corundum sand for surface sand blasting, and use compressed air to blow away the remaining corundum sand particles.

[0014] (2) Atmospheric plasma spraying is used to spray NiCrCoAlY powder onto the surface of the substrate to be sprayed to form a bonding layer.

[0015] In step (2):

[0016] The particle size of the NiCrCoAlY powder is 20 μm to 80 μm. The NiCrCoAlY powder is dried at 100° C. to 200° C. and then loaded into a powder feeder.

[0017] The substrate after sandblasting is preheated to 100°C to 200°C before atmospheric plasma spraying.

[0018] The thickness of the adhesive layer is 25 μm to 60 μm; preferably, the thickness of the adhesive layer is 28 μm to 55 μm.

[0019] (3) Use atmospheric plasma spraying to spray (V 0.2 Cr0.2 Ta 0.2 Mo 0.2 W 0.2 ) B powder is sprayed on the bonding layer prepared in step (2) to form a high entropy boride ceramic coating, that is, a high entropy ceramic coating with wide temperature range and wear resistance according to the present invention;

[0020] The atmospheric plasma spraying process parameters are: spraying angle of 85°~92°, spraying distance of 90mm~100mm, current of 550A~650A, voltage of 80V~85V, power of 40kW~44kW, flow rate of working gas Ar of 30.3slpm~40.2slpm, flow rate of auxiliary gas H2 of 6.2slpm~8.1slpm, and flow rate of powder carrier gas N2 of 3.6slpm; protective inert gas (Ar) is used to cool the sprayed substrate during the spraying process.

[0021] In step (3):

[0022] The spraying (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) B powder is dried at 100℃~200℃ and then loaded into the powder feeder.

[0023] Preheat the substrate to 100°C to 200°C before performing atmospheric plasma spraying.

[0024] The thickness of the high entropy ceramic coating is 45 μm to 83 μm.

[0025] The spraying (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B powder as raw material (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) The powder B is spray granulated and then heat treated to obtain a spherical powder; the preferred particle size is 20μm to 80μm; the specific method is as follows:

[0026] The raw material composition of spray granulation is: raw material (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) The total mass of B powder and water is 100%, (V 0.2 Cr 0.2 Ta 0.2 Mo0.2 W 0.2 ) The mass fraction of B powder is 50% to 60%, and the balance is water; polyvinyl alcohol is used as a binder in an amount of (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )4% to 5% of the mass of B powder.

[0027] The spray granulation process parameters are as follows: air inlet temperature of 230°C to 240°C, peristaltic pump speed of 25rpm to 30rpm, and atomization pressure of 0.13MPa to 0.15MPa.

[0028] The heat treatment process is carried out in a high temperature tube furnace, maintaining an inert gas argon (Ar) atmosphere to prevent high entropy (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B oxidation; first increase the temperature to 650℃ at a rate of 5℃ / min~10℃ / min and keep it for 2h, then increase the temperature to 1500℃ at a rate of 5℃ / min~10℃ / min and keep it for 2h to enhance the bonding strength inside the powder.

[0029] Beneficial effects

[0030] (1) The present invention provides a method for preparing a high-entropy ceramic coating that is wear-resistant over a wide temperature range. The method is based on a comprehensive consideration of factors such as application scenarios, deposition efficiency, and preparation costs, targeting high-entropy monoboride (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B has the characteristics of high hardness and good thermal stability, and is prepared by atmospheric plasma spraying technology; by systematically regulating the coupling relationship between spray granulation parameters, spraying process parameters and innovative application of protective atmosphere, (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B coating; the coating has a dense structure and is wear-resistant under a wide temperature range, and has strong engineering application value in the field of wear-resistant coatings.

[0031] (2) The present invention provides a method for preparing a high-entropy ceramic coating that is wear-resistant over a wide temperature range, wherein the method comprises: 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W0.2 )B material, and adaptively studied the atmospheric plasma spraying process parameters; since the flame temperature is extremely high during the spraying process, oxidation of non-oxide coating materials is very likely to occur during the spraying process, so the creative use of applying a protective atmosphere successfully suppressed the oxidation of non-oxide materials during the preparation process of atmospheric plasma spraying, expanding the application scope of atmospheric plasma spraying technology.

[0032] (3) The present invention provides a method for preparing a high-entropy ceramic coating that is wear-resistant over a wide temperature range. The method is innovative in that the raw material (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B powder morphology was controlled, and the effects of solid content and polyvinyl alcohol content on the micromorphology and powder extraction rate of the granulated powder were systematically explored. Finally, the organic additives were removed by heat treatment, and the internal bonding strength of the powder was enhanced to obtain a spray powder with good sphericity and a high powder extraction rate. This not only provides excellent raw materials for subsequent spraying, but also innovatively considers the problem of powder extraction rate in actual large-scale production processes.

[0033] (4) The present invention provides a method for preparing a high-entropy ceramic coating with wide temperature range and wear resistance, wherein the (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B is a spherical powder with a particle size of 20μm to 80μm and a fluidity of 29s / 50g to 43s / 50g, which can better meet the fluidity requirements of atmospheric plasma spraying.

[0034] (5) The present invention provides a method for preparing a high-entropy ceramic coating that is wear-resistant over a wide temperature range. The preparation process of the method is easy to implement, the coating performance is easy to control, the cost is moderate, and the practical performance is excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 For the spraying in Example 1 (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B Microstructure of powder.

[0036] Figure 2 This is the microstructural morphology of the surface of the high-entropy ceramic coating prepared in Example 1.

[0037] Figure 3This is the microstructural morphology of the cross section of the high entropy ceramic coating prepared in Example 1.

[0038] Figure 4 This is the surface phase composition of the high entropy ceramic coating prepared in Example 1.

[0039] Figure 5 This is a wear rate diagram of the high entropy ceramic coating prepared in Example 1 at room temperature to 800°C.

[0040] Figure 6 For the spraying in Example 2 (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B Microstructure of powder.

[0041] Figure 7 This is the microstructural morphology of the surface of the high-entropy ceramic coating prepared in Example 2.

[0042] Figure 8 This is the microstructural morphology of the cross section of the high entropy ceramic coating prepared in Example 2.

[0043] Figure 9 This is the surface phase composition of the high entropy ceramic coating prepared in Example 2.

[0044] Figure 10 This is a graph showing the wear rate of the high entropy ceramic coating prepared in Example 2 at room temperature to 800°C.

[0045] Figure 11 For the spraying in Comparative Example 1 (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B Microstructure of powder.

[0046] Figure 12 This is the microstructural morphology of the surface of the high entropy ceramic coating prepared in Comparative Example 1.

[0047] Figure 13 This is the microstructural morphology of the cross section of the high entropy ceramic coating prepared in Comparative Example 1.

[0048] Figure 14 This is the surface phase composition of the high entropy ceramic coating prepared in Comparative Example 1.

[0049] Figure 15 This is a graph showing the wear rate of the high entropy ceramic coating prepared in Comparative Example 1 at room temperature to 800°C. DETAILED DESCRIPTION

[0050] In the following embodiments:

[0051] Hall flowmeter is used to detect the fluidity of granulated powder.

[0052] The surface roughness was measured using a TR100 pocket roughness tester.

[0053] The phase analysis of the coating samples in the examples and comparative examples was performed using an X-ray diffractometer (Empyrean).

[0054] The microstructures of the powders to be sprayed, the coating surfaces and the cross-sections prepared in the examples and comparative examples were observed using a scanning electron microscope (SEM, FEIQuanta 200, Netherlands).

[0055] Dry sliding wear tests were conducted on a high-temperature reciprocating tribometer (Model GF-I, Lanzhou Zhongke Kaihua Technology Development Co., Ltd., Lanzhou, China). The relative humidity was 30 ± 10%. The diameter of the friction pair (silicon nitride, Si3N4) was 6 mm. Tribological tests were conducted under a load of 3 N. The constant sliding time was 30 min. The wear rate of the samples was measured using a surface wear meter (Model MT-500, Lanzhou Zhongke Kaihua Technology Development Co., Ltd., China).

[0056] Example 1

[0057] A method for preparing a high-entropy ceramic coating that is wear-resistant over a wide temperature range, the method comprising the following steps:

[0058] (1) The surface of the GH4169 nickel-based high-temperature alloy substrate to be sprayed was cleaned with analytically pure acetone to remove impurities such as dust and oil attached to the substrate surface to obtain a clean substrate surface to be sprayed. Then, 50-mesh white corundum sand was used for surface sandblasting, and the remaining white corundum sand was blown clean with compressed air to make its surface roughness Ra 5 μm.

[0059] (2) Select NiCrCoAlY powder with good fluidity and a particle size range of 20 μm to 80 μm as the bonding layer material, dry it at 100°C, and load the dried powder into a powder feeder; clamp the substrate to be sprayed on a workbench with a corresponding fixture; set the spraying route program for the robot arm that installs the spray gun; preheat the substrate at 100°C; use atmospheric plasma spraying equipment to spray NiCrCoAlY powder onto the surface of the substrate to be sprayed to form a bonding layer with a thickness of 28.47 μm;

[0060] The atmospheric plasma spraying process parameters for preparing the bonding layer are: spraying angle of 90°, spraying distance of 100 mm, current of 520 A, voltage of 62 V, power of 30 kW, flow rate of working gas Ar of 31.3 slpm, flow rate of auxiliary gas H2 of 5.0 slpm, and flow rate of powder carrier gas N2 of 3.1 slpm.

[0061] (3) Spray the (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B powder is dried at 100℃ and then loaded into the powder feeder. The substrate is preheated to 100℃ and the (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) B powder was sprayed on the bonding layer to prepare a high-entropy boride ceramic coating with a thickness of 45.50 μm, namely the wide-temperature-range wear-resistant high-entropy ceramic coating described in the present invention;

[0062] The atmospheric plasma spraying process parameters are as follows: spraying angle of 85°, spraying distance of 90 mm, current of 550 A, voltage of 80 V, power of 40 kW, flow rate of working gas Ar of 30.3 slpm, flow rate of auxiliary gas H2 of 6.2 slpm, and flow rate of powder carrier gas N2 of 3.6 slpm; protective inert gas Ar is used to cool the sprayed substrate during the spraying process.

[0063] The spraying (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B powder as raw material (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) The spherical powder is obtained by spray granulation of powder B and then heat treatment; the specific method is as follows:

[0064] The raw material composition of spray granulation is: raw material (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) The total mass of B powder and deionized water is 100%, (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2) The mass fraction of B powder is 50%, and the balance is deionized water; polyvinyl alcohol is used as a binder in an amount of (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )4% of the mass of B powder.

[0065] The spray granulation process parameters were as follows: air inlet temperature of 230 °C, peristaltic pump speed of 25 rpm, and atomization pressure of 0.13 MPa.

[0066] The heat treatment process is carried out in a high temperature tube furnace, maintaining an inert gas Ar atmosphere to prevent high entropy (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B oxidation; first increase the temperature to 650℃ at a heating rate of 5℃ / min and keep it for 2h, then increase the temperature to 1500℃ at a heating rate of 5℃ / min and keep it for 2h to enhance the bonding strength inside the powder.

[0067] Performance testing:

[0068] (1) The spraying (V) prepared in Example 1 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B powder micromorphology is characterized, such as Figure 1 After spray granulation, spherical agglomerates are formed. The particle size of the spherical powder is 20μm to 80μm, and the flowability is 43s / 50g, which meets the flowability requirements of atmospheric plasma spraying.

[0069] (2) The surface and cross-section microstructures of the high entropy ceramic coating prepared in Example 1 were observed using a scanning electron microscope. The surface morphology of the coating was as follows: Figure 2 As shown, Figure 2 Right Figure 2 The enlarged view of the left-lined area shows that the powder is fully melted and the overall surface is relatively smooth, but under this condition there are still a few particles that are not completely melted. The cross section of the coating shows a clear three-layer structure, such as Figure 3 As shown, almost no pores are observed in the cross section; the thickness of the high-entropy ceramic coating is 45.50 μm, and the thickness of the bonding layer is 28.47 μm.

[0070] (3) X-ray diffraction was used to test the surface phase composition of the high entropy ceramic coating prepared in Example 1. Figure 4 As shown, the results show that the coating is composed of (V 0.2 Cr 0.2 Ta0.2 Mo 0.2 W 0.2 The diffraction peaks of the coating are composed of )B and trace amounts of the second phase V3B4. This is because the plasma beam creates a large thermal gradient and a rapid cooling rate in the coating, creating a new dynamic process that makes it difficult for atomic diffusion to achieve ideal conditions during coating deposition. Therefore, during the non-equilibrium cooling process, the higher-melting-point borides containing W, Mo, and Ta crystallize preferentially over the lower-melting-point vanadium boride, ultimately forming V3B4.

[0071] (4) The high entropy ceramic coating prepared in Example 1 was subjected to friction and wear tests at temperatures ranging from room temperature to 800°C using a dry sliding wear tester. Figure 5 The figure below shows the wear rate of the coating at different test temperatures. It can be observed that the wear rate is positively correlated with temperature. The higher the temperature, the higher the wear rate. Compared to 800°C, it has better wear resistance in the temperature range of room temperature to 600°C.

[0072] Example 2

[0073] A method for preparing a high-entropy ceramic coating that is wear-resistant over a wide temperature range, the method comprising the following steps:

[0074] (1) The surface of the GH4169 nickel-based high-temperature alloy substrate to be sprayed was cleaned with analytically pure acetone to remove impurities such as dust and oil attached to the substrate surface to obtain a clean substrate surface to be sprayed. Then, 50-mesh white corundum sand was used for surface sandblasting, and the remaining white corundum sand was blown clean with compressed air to make its surface roughness Ra 8 μm.

[0075] (2) Select NiCrCoAlY powder with good fluidity and a particle size range of 20 μm to 80 μm as the bonding layer material, dry it at 200°C, and load the dried powder into a powder feeder; clamp the substrate to be sprayed on a workbench with a corresponding fixture; set the spraying route program for the robot arm that installs the spray gun; preheat the substrate at 200°C; use atmospheric plasma spraying equipment to spray NiCrCoAlY powder onto the surface of the substrate to be sprayed to form a bonding layer with a thickness of 54.43 μm;

[0076] The atmospheric plasma spraying process parameters for preparing the bonding layer are: spraying angle of 90°, spraying distance of 100 mm, current of 520 A, voltage of 62 V, power of 30 kW, flow rate of working gas Ar of 31.3 slpm, flow rate of auxiliary gas H2 of 5.0 slpm, and flow rate of powder carrier gas N2 of 3.1 slpm.

[0077] (3) Spray the (V 0.2 Cr0.2 Ta 0.2 Mo 0.2 W 0.2 )B powder is dried at 200℃ and then loaded into the powder feeder. The substrate is preheated to 200℃ and the (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) B powder was sprayed on the bonding layer to prepare a high-entropy boride ceramic coating with a thickness of 82.06 μm, i.e., a wide-temperature-range wear-resistant high-entropy ceramic coating according to the present invention;

[0078] The atmospheric plasma spraying process parameters are as follows: spraying angle of 92°, spraying distance of 100 mm, current of 650 A, voltage of 85 V, power of 44 kW, flow rate of working gas Ar of 40.2 slpm, flow rate of auxiliary gas H2 of 8.1 slpm, and flow rate of powder carrier gas N2 of 3.6 slpm; protective inert gas Ar is used to cool the sprayed substrate during the spraying process.

[0079] The spraying (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B powder as raw material (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) The spherical powder is obtained by spray granulation of powder B and then heat treatment; the specific method is as follows:

[0080] The raw material composition of spray granulation is: raw material (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) The total mass of B powder and deionized water is 100%, (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) The mass fraction of B powder is 60%, and the balance is deionized water; polyvinyl alcohol is used as a binder in an amount of (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )5% of the mass of B powder.

[0081] The spray granulation process parameters were as follows: air inlet temperature of 240 °C, peristaltic pump speed of 30 rpm, and atomization pressure of 0.15 MPa.

[0082] The heat treatment process is carried out in a high temperature tube furnace, maintaining an inert gas Ar atmosphere to prevent high entropy (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) B oxidation. First, heat the temperature to 650℃ at a rate of 10℃ / min and keep it for 2h, then heat it to 1500℃ at a rate of 10℃ / min and keep it for 2h to enhance the bonding strength inside the powder.

[0083] Performance testing:

[0084] (1) The spraying (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B powder micromorphology is characterized, such as Figure 6 After spray granulation, spherical agglomerates are formed, and the spherical powder is more complete and the particle size is more uniform, with a particle size of 20μm to 80μm. The flowability is tested to be 29s / 50g, which is improved compared with Example 1 and meets the flowability requirements of atmospheric plasma spraying.

[0085] (2) The surface and cross-section microstructures of the high entropy ceramic coating prepared in Example 2 were observed using a scanning electron microscope. The surface morphology of the coating was as follows: Figure 7 As shown, Figure 7 Right Figure 7 The partial enlarged view of the left-lined area shows that with the adjustment of the spraying parameters, the spreadability and surface roughness of the coating have been significantly improved. This is because the increase in power causes the spherical powder to be heated to a higher temperature in the plasma flame, thereby making the powder more molten. This results in the droplets being able to spread more fully when they come into contact with the bonding layer, making the coating surface more dense and smooth. The coating cross section shows a clear three-layer structure, such as Figure 8 As shown, the thickness of the coating and the bonding layer are increased relative to that of Example 1, the thickness of the high entropy ceramic coating is 82.06 μm, and the thickness of the bonding layer is 54.43 μm.

[0086] (3) X-ray diffraction was used to test the surface phase composition of the high entropy ceramic coating prepared in Example 2. Figure 9 As shown, the results show that the coating is still composed of (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W0.2 )B and the diffraction peak of a trace second phase V3B4; the relative intensity of the V3B4 diffraction peak is slightly increased compared with that in Example 1.

[0087] (4) The high entropy ceramic coating prepared in Example 2 was subjected to friction and wear tests in the temperature range from room temperature to 800°C using a dry sliding wear tester. Figure 10 The figure below shows the wear rate of the coating at different test temperatures. It can be observed that the wear rate shows a positive correlation with temperature, with the higher the temperature, the higher the wear rate. However, the wear rate at each temperature is lower than that of Example 1, indicating that the prepared coating has superior wear resistance. Similarly to Example 1, the coating has even better wear resistance in the temperature range of room temperature to 600°C compared to 800°C.

[0088] Comparative Example 1

[0089] A method for preparing a high-entropy ceramic coating that is wear-resistant over a wide temperature range, the method comprising the following steps:

[0090] (2) The surface of the GH4169 nickel-based high-temperature alloy substrate to be sprayed was cleaned with analytically pure acetone to remove impurities such as dust and oil attached to the substrate surface to obtain a clean substrate surface to be sprayed. The surface was then sandblasted with 50-mesh white corundum sand, and the remaining white corundum sand was blown clean with compressed air to make its surface roughness Ra 3 μm.

[0091] (2) Select NiCrCoAlY powder with good fluidity and a particle size range of 20 μm to 80 μm as the bonding layer material, dry it at 200°C, and load the dried powder into a powder feeder; clamp the substrate to be sprayed on a workbench with a corresponding fixture; set the spraying route program for the robot arm that installs the spray gun; preheat the substrate at 200°C; use atmospheric plasma spraying equipment to spray NiCrCoAlY powder onto the surface of the substrate to be sprayed to form a bonding layer with a thickness of 26.80 μm;

[0092] The atmospheric plasma spraying process parameters for preparing the bonding layer are: spraying angle of 90°, spraying distance of 100 mm, current of 520 A, voltage of 62 V, power of 30 kW, flow rate of working gas Ar of 31.3 slpm, flow rate of auxiliary gas H2 of 5.0 slpm, and flow rate of powder carrier gas N2 of 3.1 slpm.

[0093] (3) Spray the (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2)B powder is dried at 300℃ and then loaded into the powder feeder. The substrate is preheated to 200℃ and the (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) B powder was sprayed on the bonding layer to prepare a high entropy boride ceramic coating with a thickness of 84.85 μm;

[0094] The atmospheric plasma spraying process parameters are as follows: spraying angle of 92°, spraying distance of 100 mm, current of 550 A, voltage of 65 V, power of 38 kW, flow rate of working gas Ar of 39.3 slpm, flow rate of auxiliary gas H2 of 6.2 slpm, and flow rate of powder carrier gas N2 of 3.6 slpm; compressed air is used to cool the sprayed substrate during the spraying process.

[0095] The spraying (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B powder as raw material (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) The powder B is spray granulated and then heat treated to obtain spherical powder with a particle size of 20μm to 150μm. The specific method is as follows:

[0096] The raw material composition of spray granulation is: raw material (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) The total mass of B powder and deionized water is 100%, (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) The mass fraction of B powder is 65%, and the balance is deionized water; polyvinyl alcohol is used as a binder in an amount of (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )6% of B powder.

[0097] The spray granulation process parameters were as follows: air inlet temperature of 240 °C, peristaltic pump speed of 30 rpm, and atomization pressure of 0.15 MPa.

[0098] The heat treatment process is carried out in a high temperature tube furnace, maintaining an inert gas Ar atmosphere to prevent high entropy (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) B oxidation. First, heat the temperature to 650℃ at a rate of 10℃ / min and keep it for 2h, then heat the temperature to 1500℃ at a rate of 10℃ / min and keep it for 2h.

[0099] Performance testing:

[0100] (1) The spraying (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B powder micromorphology is characterized, such as Figure 11 As shown in the figure, due to the high solid content and binder content of the slurry, the spherical powders formed agglomerated together, resulting in a very uneven particle size distribution of 20μm to 150μm. The flowability was tested to be 104s / 50g, which does not meet the flowability requirements for atmospheric plasma spraying.

[0101] (2) The surface and cross-section microstructures of the high entropy ceramic coating prepared in Comparative Example 1 were observed using a scanning electron microscope. The surface morphology of the coating was as follows: Figure 12 As shown, Figure 12 Right Figure 12 The enlarged view of the left-lined area shows that the surface roughness of the coating is significantly higher. In the SEM enlarged view, oxidation products such as flakes, rods and spheres can be observed. This is because the protective inert gas Ar was not used to cool the sprayed substrate during the spraying process. On the one hand, it is due to the high entropy (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B Powder itself will oxidize at high temperature. Although the spraying process is very fast during atmospheric plasma spraying, the high entropy powder melted by the high temperature flame will inevitably entrain some of the surrounding air when sprayed onto the substrate surface at high speed, causing oxidation of the coating. On the other hand, after spraying, the instantaneous temperature of the coating surface can reach over 800℃. Under normal atmospheric conditions, the coating will naturally cool down, which will inevitably cause oxidation of the coating surface. The cross section of the coating shows a clear three-layer structure, such as Figure 13As shown, numerous holes can be seen near the bonding layer, resulting in a loose overall structure. This is due to the low spray power, which results in insufficient plasma flame temperature. The spherical powder delivered into the flame is only partially melted, and the particles are connected only by the molten portion, resulting in a loose coating. The high-entropy ceramic coating is 84.85 μm thick, while the bonding layer is 26.80 μm thick.

[0102] (3) X-ray diffraction was used to test the surface phase composition of the high entropy ceramic coating prepared in Comparative Example 1. Figure 14 As shown, the main peak of the XRD diffraction peak of the coating is no longer (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B, and is replaced by various oxide diffraction peaks (WO3, Ta2O5, V2O3) and the diffraction peak of elemental W.

[0103] (4) A dry sliding wear tester was used to conduct friction and wear tests on the high entropy ceramic coating prepared in Comparative Example 1 at temperatures ranging from room temperature to 800°C. Figure 15 Figure 3 is a graph showing the wear rate of the coating at different test temperatures. Compared with Examples 1 and 2, the wear rate values of the coating at all temperatures are reduced by about 1 to 2 orders of magnitude, and the wear resistance of the coating is greatly reduced. On the one hand, this is due to the loose and porous microstructure of the coating caused by insufficient spraying power. On the other hand, since the protective inert gas Ar is not used to cool the spray substrate during the process, the prepared coating itself undergoes severe oxidation.

[0104] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a high-entropy ceramic coating with wide temperature range and wear resistance, characterized by: (1) Sandblasting the clean surface of the substrate to be sprayed to a surface roughness Ra of 5 μm to 8 μm; (2) spraying NiCrCoAlY powder onto the surface of the substrate to be sprayed by atmospheric plasma spraying to form a bonding layer; (3) Use atmospheric plasma spraying to spray (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) B powder is sprayed on the bonding layer prepared in step (2) to prepare a high-entropy ceramic coating that is wear-resistant over a wide temperature range; For spraying (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B powder as raw material (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) Spherical powder obtained by spray granulation of powder B and subsequent heat treatment; The atmospheric plasma spraying process parameters are: spraying angle of 85°~92°, spraying distance of 90mm~100mm, current of 550A~650A, voltage of 80V~85V, power of 40kW~44kW, flow rate of working gas Ar of 30.3slpm~40.2slpm, flow rate of auxiliary gas H2 of 6.2slpm~8.1slpm, and flow rate of powder carrier gas N2 of 3.6slpm; protective inert gas Ar is used to cool the sprayed substrate during the spraying process.

2. The method for preparing a wide temperature range wear-resistant high-entropy ceramic coating according to claim 1, characterized in that: The raw material composition of spray granulation is: raw material (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) The total mass of B powder and water is 100%, (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) The mass fraction of B powder is 50% to 60%, and the balance is water; the amount of polyvinyl alcohol is (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) 4% to 5% of the mass of B powder; The spray granulation process parameters are: air inlet temperature 230℃~240℃, peristaltic pump speed 25rpm~30rpm, atomization pressure 0.13MPa~0.15MPa; The heat treatment process is carried out in a high-temperature tube furnace, maintaining an inert gas Ar atmosphere; first, the temperature is raised to 650°C at a heating rate of 5°C / min to 10°C / min and kept warm for 2 hours, and then the temperature is raised to 1500°C at a heating rate of 5°C / min to 10°C / min and kept warm for 2 hours.

3. The method for preparing a wide temperature range wear-resistant high-entropy ceramic coating according to claim 2, characterized in that: For spraying (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 )B powder particle size is 20μm~80μm.

4. The method for preparing a wide temperature range wear-resistant high-entropy ceramic coating according to any one of claims 1 to 3, characterized in that: The thickness of the bonding layer is 25 μm to 60 μm; the thickness of the high-entropy ceramic coating is 45 μm to 83 μm.

5. The method for preparing a wide temperature range wear-resistant high-entropy ceramic coating according to claim 4, characterized in that: The thickness of the adhesive layer is 28 μm to 55 μm.

6. The method for preparing a wide temperature range wear-resistant high-entropy ceramic coating according to claim 1, characterized in that: In step (2), the particle size of the NiCrCoAlY powder is 20 μm to 80 μm, and the NiCrCoAlY powder is dried at 100° C. to 200° C. and then loaded into a powder feeder; the sandblasted substrate is preheated to 100° C. to 200° C. and then subjected to atmospheric plasma spraying; In step (3), the spraying (V 0.2 Cr 0.2 Ta 0.2 Mo 0.2 W 0.2 ) B powder is dried at 100℃~200℃ and then loaded into the powder feeder; Preheat the substrate to 100°C to 200°C before performing atmospheric plasma spraying.

7. The method for preparing a wide temperature range wear-resistant high-entropy ceramic coating according to claim 1, characterized in that: The substrate is metal or alloy.

8. The method for preparing a wide temperature range wear-resistant high-entropy ceramic coating according to claim 7, characterized in that: The substrate is a high-temperature nickel-based alloy.

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