A steam turbine blade ultra-high temperature coating and a method of making the same

Abstract

The application provides a steam turbine blade ultrahigh-temperature coating and a preparation method thereof, and relates to the technical field of material surface treatment, and comprises the following components in mass ratio: yttrium stabilized zirconium 20-30 parts, titanium aluminum nitride 15-20 parts, lanthanum magnesium aluminum spinel 10-15 parts, nano cerium oxide 5-10 parts, cobalt-based alloy 10-15 parts, rare earth element mixture 1-5 parts, hexagonal boron nitride 5-10 parts, SiC nano particles 5-10 parts, and chromium carbide 2-5 parts. The synergistic effect of the lanthanum magnesium aluminum spinel and the rare earth element mixture greatly reduces the grain growth rate of the coating at high temperature, thereby improving the stability at extreme temperature. The protective layer formed by the decomposition of the chromium carbide and the SiC nano particles jointly inhibit the sulfur corrosion, further improve the stability, and ensure the performance of the coating under high temperature conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material surface treatment, and particularly relates to a super-high-temperature coating for a steam turbine blade and a preparation method thereof. BACKGROUND

[0002] Steam turbine blades are the core components of steam turbines, a key power equipment, and are designed with great precision and are crucial to function. They are usually installed on the rim of the steam turbine rotor and rotate at high circumferential speed, directly responsible for converting the thermal energy of steam into mechanical energy efficiently. During the operation of the steam turbine, high-temperature and high-pressure steam impacts the blades, propelling their rotation and driving the rotor, which in turn drives the generator to generate electricity or performs other mechanical work. Steam turbine blades not only bear extremely high temperature, pressure and centrifugal force, but also face severe challenges such as impurities in steam, corrosion, and wear and fatigue caused by long-term operation. Therefore, the material selection, structural design, manufacturing process and protective measures of the steam turbine blades are extremely critical, directly related to the efficiency, reliability and service life of the steam turbine. Modern steam turbine blades mostly use advanced alloy materials and are processed through precise machining and surface coating treatment technology to ensure their excellent performance under extreme working conditions.

[0003] In the coating of steam turbine blades, the traditional MCrAlY coating is prone to form a loose Al2O3 film under high temperature conditions. Since the loose Al2O3 film cannot effectively protect the inside of the coating from oxidation, the coating material will gradually be oxidized, resulting in performance degradation and reduced service life. The traditional ceramic coating is prone to thermal shock spalling due to the difference in thermal expansion coefficient between the metal matrix and the interface stress concentration. Therefore, the traditional coating has limited high-temperature stability. Thus, the present application proposes a super-high-temperature coating for a steam turbine blade and a preparation method thereof to solve the problems in the prior art. SUMMARY

[0004] To solve the above problems, the present application proposes a super-high-temperature coating for a steam turbine blade and a preparation method thereof. The super-high-temperature coating for a steam turbine blade greatly reduces the grain growth rate at high temperatures through the synergistic effect of lanthanum-magnesium-aluminum spinel and rare earth mixture, thereby improving the stability at extreme temperatures.

[0005] To achieve the purpose of the present application, the present application realizes the following technical scheme: a super-high-temperature coating for a steam turbine blade, comprising the following components by mass ratio: yttrium-stabilized zirconium (Y-ZrO2) 20-30 parts, titanium aluminum nitride (TiAlN) 15-20 parts, lanthanum-magnesium-aluminum spinel (LaMgAl 11 O 19)10-15 parts, nano cerium oxide (CeO2) 5-10 parts, cobalt-based alloy (Co-Cr-Al-Y) 10-15 parts, rare earth element mixture 1-5 parts, hexagonal boron nitride (h-BN) 5-10 parts, SiC nanoparticles 5-10 parts, chromium carbide (Cr3C2) 2-5 parts.

[0006] Further improvement lies in that the following mass ratio components are included: yttrium stabilized zirconium oxide (Y-ZrO2) 25 parts, titanium aluminum nitride (TiAlN) 18 parts, lanthanum magnesium aluminum spinel (LaMgAl 11 O 19 )12 parts, nano cerium oxide (CeO2) 8 parts, cobalt-based alloy (Co-Cr-Al-Y) 12 parts, rare earth element mixture 3 parts, hexagonal boron nitride (h-BN) 8 parts, SiC nanoparticles 7 parts, chromium carbide (Cr3C2) 3 parts.

[0007] Further improvement lies in that the Y2O3 content in the yttrium stabilized zirconium oxide is 8%, and the particle size is 1-5 μm; the Al content in the titanium aluminum nitride is 60-70%, and the particle size is ≤10 μm.

[0008] Further improvement lies in that the atomic ratio of La:Mg:Al in the lanthanum magnesium aluminum spinel is 1:1:11; the particle size of the nano cerium oxide is 5-10 nm, and the purity is ≥99.9%; in the cobalt-based alloy, the mass ratio of Co:Cr:Al:Y is 70:20:8:2.

[0009] Further improvement lies in that in the rare earth element mixture, the mass ratio of La:Ce:Nb is 4:4:2; the purity of the hexagonal boron nitride is ≥98%, and the lamella thickness is ≤1 μm.

[0010] A preparation method of a super-high-temperature coating of a steam turbine blade, comprising the following steps:

[0011] S1: hydrogen reduction treatment is performed on the cobalt-based alloy, and the titanium aluminum nitride and the chromium carbide are ball milled under argon;

[0012] S2: the components are added into anhydrous ethanol according to the proportion, ultrasonic dispersion is performed, ball milling is performed, and spray drying is performed to obtain spherical composite powder;

[0013] S3: the composite powder is sprayed onto the steam turbine blade by using a supersonic flame spraying method to form a coating;

[0014] S4: vacuum nitriding treatment and gradient annealing are performed on the coating to solidify the coating.

[0015] Further improvement lies in that: in the S1, the cobalt-based alloy powder is subjected to hydrogen reduction treatment, the treatment is carried out at 600 DEG C for 2h, the flow rate of H2 is controlled to be 2L / min, the titanium aluminum nitride and the chromium carbide are subjected to ball milling treatment under argon, the ball milling is carried out for 4h, the ball-to-material ratio is controlled to be 8:1, and the rotating speed is 450 rpm.

[0016] Further improvement lies in that: in the S2, the components are added into anhydrous ethanol according to the proportion, the ultrasonic dispersion is carried out for 2h, then ball milling is carried out for 8h, spray drying is carried out to obtain spherical composite powder, the particle size distribution is controlled to be 20-80mu m, and the fluidity is controlled to be less than or equal to 25s / 50g.

[0017] Further improvement lies in that: in the S3, when the supersonic flame spraying method is adopted, the spraying fuel is C3H6 / O2 mixed gas, the flow rate ratio is 1:1.2, the fuel flow rate is controlled to be 250L / h, the spraying distance is 300mm, the sprayed substrate is preheated to 500 DEG C, and the thickness of the sprayed coating is controlled to be 150±15mu m.

[0018] Further improvement lies in that: in the S4, in the vacuum nitriding treatment, the temperature is controlled to be 1050 DEG C, the treatment is carried out for 3h, the nitrogen pressure is controlled to be 0.5MPa, and the gradient annealing includes the following stages: the treatment is carried out at 1200 DEG C for 1h under argon protection; the treatment is carried out at 800 DEG C for 4h under vacuum environment; and air cooling is carried out to room temperature.

[0019] The beneficial effects of the present application are:

[0020] 1. The present application realizes the synergistic effect of lanthanum magnesium aluminum spinel and rare earth mixture, greatly reduces the grain growth rate of the coating at high temperature, thereby improving the stability at extreme temperature, adopts chromium carbide to form a protective layer, and SiC nanoparticles are used to jointly inhibit sulfur corrosion, thereby further improving the stability and ensuring the performance of the coating under high temperature conditions.

[0021] 2. The cubic crystal structure of yttrium stabilized zirconium oxide and the face-centered cubic structure of titanium aluminum nitride form an atomic-level coherent interface, crack propagation is inhibited through the interface stress transmission mechanism, the coating fracture toughness is improved, the continuous gradient transition structure of lanthanum magnesium aluminum spinel and cobalt-based alloy effectively relieves the thermal stress concentration of the coating-substrate interface, the number of thermal shock cycles is improved, the layered crystal structure of hexagonal boron nitride provides self-lubricating function, and a lubricating film-reinforced phase composite system is formed with SiC nanoparticles, thereby reducing the wear rate and enhancing the erosion resistance. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The flow chart of the present application. DETAILED DESCRIPTION

[0023] In order to deepen the understanding of the present application, the present application will be further described below in conjunction with examples, which are only used to explain the present application and do not constitute a limitation on the scope of protection of the present application.

[0024] Example 1

[0025] According to Figure 1 The present embodiment proposes a steam turbine blade ultra-high temperature coating, characterized by comprising the following mass ratio components: yttrium stabilized zirconia (Y-ZrO2) 20 parts, titanium aluminum nitride (TiAlN) 15 parts, lanthanum magnesium aluminum spinel (LaMgAl 11 O 19 ) 10 parts, nano cerium oxide (CeO2) 5 parts, cobalt-based alloy (Co-Cr-Al-Y) 10 parts, rare earth element mixture 1 part, hexagonal boron nitride (h-BN) 5 parts, SiC nanoparticles 5 parts, chromium carbide (Cr3C2) 2 parts.

[0026] Yttrium stabilized zirconia: through the doping of yttrium, the crystal form of zirconia is stabilized, and its thermal stability and oxidation resistance are improved. Titanium aluminum nitride: forms a hard phase, significantly improving the hardness and wear resistance of the coating. Lanthanum magnesium aluminum spinel: optimizes the microstructure of the coating, improves the thermal shock stability and oxidation resistance. Nano cerium oxide: as an oxidizing agent scavenger, effectively reduces oxidation damage. Cobalt-based alloy: provides high temperature strength and toughness, ensuring strong bonding of the coating and the substrate. Rare earth element mixture: optimizes coating performance, improves oxidation resistance and corrosion resistance. Hexagonal boron nitride: as a solid lubricant, reduces wear and extends the service life of the coating. SiC nanoparticles: enhance the hardness and wear resistance of the coating, improve the thermal stability. Chromium carbide: forms a hard phase, improves the hardness and oxidation resistance of the coating.

[0027] The Y2O3 content in the yttrium stabilized zirconia is 8%, and the particle size is 1-5 μm; the Al content in the titanium aluminum nitride is 60-70%, and the particle size is ≤10 μm. The atomic ratio of La:Mg:Al in the lanthanum magnesium aluminum spinel is 1:1:11; the particle size of the nano cerium oxide is 5-10 nm, and the purity is ≥99.9%; the mass ratio of Co:Cr:Al:Y in the cobalt-based alloy is 70:20:8:2. The mass ratio of La:Ce:Nb in the rare earth element mixture is 4:4:2; the purity of the hexagonal boron nitride is ≥98%, and the lamella thickness is ≤1 μm.

[0028] A preparation method of a steam turbine blade ultra-high temperature coating, comprising the following steps:

[0029] The cobalt-based alloy was subjected to hydrogen reduction treatment by ball milling titanium aluminum nitride and chromium carbide under argon gas; the cobalt-based alloy powder was subjected to hydrogen reduction treatment at 600℃ for 2h, with the H2 flow rate controlled at 2L / min, and the titanium aluminum nitride and chromium carbide were ball milled under argon gas for 4h, with the ball-to-material ratio controlled at 8:1 and the rotation speed at 450rpm.

[0030] The components were added to anhydrous ethanol according to the formula, ultrasonically dispersed, ball-milled, and spray-dried to obtain spherical composite powder; the components were added to anhydrous ethanol according to the formula, ultrasonically dispersed for 2 hours, ball-milled for 8 hours, and spray-dried to obtain spherical composite powder, with the particle size distribution controlled at 20-80μm and the flowability ≤25s / 50g.

[0031] A composite powder was sprayed onto the turbine blades using a supersonic flame spraying method to form a coating. When using the supersonic flame spraying method, the spraying fuel was a C3H6 / O2 mixture with a flow ratio of 1:1.2. The fuel flow rate was controlled at 250 L / h, the spraying distance was 300 mm, the substrate was preheated to 500 °C, and the thickness of the coating after spraying was controlled at 150 ± 15 μm.

[0032] The coating was subjected to vacuum nitriding and gradient annealing, followed by curing. In the vacuum nitriding process, the temperature was controlled at 1050℃ for 3 hours, and the nitrogen pressure was controlled at 0.5 MPa. The gradient annealing included the following stages: 1 hour at 1200℃ under argon protection; 4 hours at 800℃ under vacuum; and air cooling to room temperature. Nitriding + gradient annealing resulted in the formation of a continuous Cr2N-TiN layer on the surface, improving wear resistance by 3 times (friction coefficient 0.15 → 0.05); h-BN directional distribution: by controlling the spraying angle, parallel arrangement of h-BN layers was achieved, increasing thermal conductivity to 28 W / (m·K). Under 1400℃ gas scouring conditions (flow rate 120 m / s), the coating life was ≥5000 hours; thermal cycling stress was reduced by 72%.

[0033] Example 2

[0034] according to Figure 1 As shown, this embodiment proposes an ultra-high temperature coating for steam turbine blades, comprising the following mass ratio components: 25 parts of yttrium-stabilized zirconium oxide (Y-ZrO2), 18 parts of titanium aluminum nitride (TiAlN), and lanthanum magnesium aluminum spinel (LaMgAl). 11 O 19 12 parts of cerium oxide nanoparticles (CeO2), 8 parts of cobalt-based alloy (Co-Cr-Al-Y), 12 parts of rare earth element mixture, 3 parts of hexagonal boron nitride (h-BN), 7 parts of SiC nanoparticles, and 3 parts of chromium carbide (Cr3C2).

[0035] Yttrium stabilized zirconia: Stabilize the crystal form of zirconia through yttrium doping, improve its thermal stability and oxidation resistance. Titanium aluminum nitride: Form a hard phase, significantly improve the hardness and wear resistance of the coating. Lanthanum magnesium aluminum spinel: Optimize the microstructure of the coating, improve the thermal shock stability and oxidation resistance. Nano cerium oxide: As an oxidant scavenger, effectively reduce oxidation damage. Cobalt-based alloy: Provide high temperature strength and toughness, ensure the strong combination of the coating and the substrate. Rare earth element mixture: Optimize the performance of the coating, improve the oxidation resistance and corrosion resistance. Hexagonal boron nitride: As a solid lubricant, reduce wear and tear, prolong the service life of the coating. SiC nanoparticles: Enhance the hardness and wear resistance of the coating, improve the thermal stability. Chromium carbide: Form a hard phase, improve the hardness and oxidation resistance of the coating.

[0036] The Y2O3 content in the yttrium stabilized zirconia is 8%, and the particle size is 1-5μm; the Al content in the titanium aluminum nitride is 60-70%, and the particle size is ≤10μm. The atomic ratio of La:Mg:Al in the lanthanum magnesium aluminum spinel is 1:1:11; the particle size of the nano cerium oxide is 5-10nm, and the purity is ≥99.9%; the mass ratio of Co:Cr:Al:Y in the cobalt-based alloy is 70:20:8:2. The mass ratio of La:Ce:Nb in the rare earth element mixture is 4:4:2; the purity of the hexagonal boron nitride is ≥98%, and the lamella thickness is ≤1μm.

[0037] A method for preparing a super-high-temperature coating for a steam turbine blade, comprising the following steps:

[0038] The cobalt-based alloy is subjected to hydrogen reduction treatment, and the titanium aluminum nitride and chromium carbide are subjected to ball milling treatment under argon. The cobalt-based alloy powder is subjected to hydrogen reduction treatment at 600℃ for 2h, with the flow rate of H2 controlled at 2L / min. The titanium aluminum nitride and chromium carbide are subjected to ball milling treatment under argon for 4h, with the ball-to-material ratio controlled at 8:1 and the rotation speed at 450rpm.

[0039] The components are added to anhydrous ethanol in the specified proportions, ultrasonically dispersed, ball milled, and spray dried to obtain spherical composite powder. The components are added to anhydrous ethanol in the specified proportions, ultrasonically dispersed for 2h, ball milled for 8h, and spray dried to obtain spherical composite powder, with the particle size distribution controlled at 20-80μm and the flowability ≤25s / 50g.

[0040] The composite powder is sprayed onto the steam turbine blade using high-velocity oxygen fuel spraying to form a coating. When using high-velocity oxygen fuel spraying, the spraying fuel is C3H6 / O2 mixed gas with a flow rate ratio of 1:1.2, the fuel flow rate is controlled at 250L / h, the spraying distance is 300mm, the sprayed substrate is preheated to 500℃, and the thickness of the sprayed coating is controlled at 150±15μm.

[0041] The coating is vacuum nitrided and gradient annealed to solidify the coating. In the vacuum nitriding process, the temperature is controlled at 1050°C for 3h, the nitrogen pressure is controlled at 0.5MPa, and the gradient annealing includes the following stages: 1200°C for 1h under argon protection, 800°C for 4h under vacuum, and air cooling to room temperature. Nitriding + gradient annealing: a continuous Cr2N-TiN layer is formed on the surface, the wear resistance is improved by 3 times (friction coefficient 0.15→0.05); h-BN directional distribution: h-BN lamellae are arranged in parallel by controlling the spraying angle, and the thermal conductivity is improved to 28W / (m·K). Under the condition of 1400°C gas scouring (flow rate 120m / s), the coating life is ≥5000h; the thermal cycle stress is reduced by 72%.

[0042] Example Three

[0043] According to Figure 1 The embodiment proposes a super-high-temperature coating for steam turbine blades, including the following components by mass: yttrium-stabilized zirconia (Y-ZrO2) 30 parts, titanium aluminum nitride (TiAlN) 20 parts, lanthanum magnesium aluminum spinel (LaMgAl 11 O 19 ) 15 parts, nano cerium oxide (CeO2) 10 parts, cobalt-based alloy (Co-Cr-Al-Y) 15 parts, rare earth element mixture 5 parts, hexagonal boron nitride (h-BN) 10 parts, SiC nanoparticles 10 parts, and chromium carbide (Cr3C2) 5 parts.

[0044] Yttrium-stabilized zirconia: through yttrium doping, the crystal form of zirconia is stabilized, improving its thermal stability and oxidation resistance. Titanium aluminum nitride: forms a hard phase, significantly improving the hardness and wear resistance of the coating. Lanthanum magnesium aluminum spinel: optimizes the microstructure of the coating, improves the thermal shock stability and oxidation resistance. Nano cerium oxide: as an oxidizing agent scavenger, effectively reduces oxidation damage. Cobalt-based alloy: provides high-temperature strength and toughness, ensuring strong bonding of the coating to the substrate. Rare earth element mixture: optimizes coating performance, improves oxidation resistance and corrosion resistance. Hexagonal boron nitride: as a solid lubricant, reduces wear and extends the service life of the coating. SiC nanoparticles: enhance the hardness and wear resistance of the coating, improve the thermal stability. Chromium carbide: forms a hard phase, improving the hardness and oxidation resistance of the coating.

[0045] The Y2O3 content of the yttrium stabilized zirconium oxide is 8%, and the particle size is 1-5 μm; the Al content of the titanium aluminum nitride is 60-70%, and the particle size is ≤10 μm. The La:Mg:Al atomic ratio of the lanthanum magnesium aluminum spinel is 1:1:11; the particle size of the nano cerium oxide is 5-10 nm, and the purity is ≥99.9%; the Co:Cr:Al:Y mass ratio of the cobalt-based alloy is 70:20:8:2. The La:Ce:Nb mass ratio of the rare earth element mixture is 4:4:2; the purity of the hexagonal boron nitride is ≥98%, and the lamella thickness is ≤1 μm.

[0046] A preparation method of a steam turbine blade ultra-high temperature coating, comprising the following steps:

[0047] The cobalt-based alloy is subjected to hydrogen reduction treatment, and the titanium aluminum nitride and the chromium carbide are subjected to ball milling treatment under argon; the cobalt-based alloy powder is subjected to hydrogen reduction treatment at 600°C for 2 h, the flow rate of H2 is controlled to be 2 L / min, the titanium aluminum nitride and the chromium carbide are subjected to ball milling treatment under argon for 4 h, the ball-to-material ratio is controlled to be 8:1, and the rotation speed is 450 rpm;

[0048] The components are added into anhydrous ethanol according to the proportion, ultrasonic dispersion is performed, ball milling is performed, spray drying is performed to obtain spherical composite powder; the components are added into anhydrous ethanol according to the proportion, ultrasonic dispersion is performed for 2 h, ball milling is performed for 8 h, spray drying is performed to obtain spherical composite powder, the particle size distribution is controlled to be 20-80 μm, and the fluidity is ≤25 s / 50 g;

[0049] The composite powder is sprayed onto the steam turbine blade by using a high-velocity oxygen fuel spraying method to form a coating; when the high-velocity oxygen fuel spraying method is used, the spraying fuel is C3H6 / O2 mixed gas, the flow rate ratio is 1:1.2, the fuel flow rate is controlled to be 250 L / h, the spraying distance is 300 mm, the sprayed substrate is preheated to 500°C, and the thickness of the sprayed coating is controlled to be 150±15 μm;

[0050] The coating is subjected to vacuum nitriding treatment and gradient annealing to solidify the coating. In the vacuum nitriding treatment, the temperature is controlled to be 1050°C, the treatment time is 3 h, and the nitrogen pressure is controlled to be 0.5 MPa. The gradient annealing comprises the following stages: treatment at 1200°C for 1 h under argon protection, treatment at 800°C for 4 h in a vacuum environment, and air cooling to room temperature. After nitriding+gradient annealing, a continuous Cr2N-TiN layer is formed on the surface, the wear resistance is improved by 3 times (friction coefficient 0.15→0.05), and the h-BN is directionally distributed (the h-BN lamella is arranged in parallel by controlling the spraying angle, and the thermal conductivity is improved to 28 W / (m·K). Under the condition of 1400°C gas scouring (flow rate 120 m / s), the service life of the coating is ≥5000 h, and the thermal cycle stress is reduced by 72%.

[0051] According to embodiment one, embodiment two and embodiment three, the coating layer prepared by the components in the following quality ratio: yttrium stabilized zirconium oxide (Y-ZrO2) 20-30 parts, titanium aluminum nitride (TiAlN) 15-20 parts, lanthanum magnesium aluminum spinel (LaMgAl 11 O 19 ) 10-15 parts, nano cerium oxide (CeO2) 5-10 parts, cobalt-based alloy (Co-Cr-Al-Y) 10-15 parts, rare earth element mixture 1-5 parts, hexagonal boron nitride (h-BN) 5-10 parts, SiC nanoparticles 5-10 parts, chromium carbide (Cr3C2) 2-5 parts, has stronger stability at extreme temperature.

[0052] Verification example:

[0053]

[0054] The lanthanum magnesium aluminum spinel and the rare earth mixture in the application have a synergistic effect, which reduces the grain growth rate of the coating layer by 80% at high temperature, thereby improving the stability at extreme temperature. The chromium carbide decomposes to form a protective layer, which, together with the SiC nanoparticles, inhibits sulfur corrosion, further improves the stability, and ensures the performance of the coating layer under high temperature conditions. The cubic crystal structure of yttrium stabilized zirconium oxide and the face-centered cubic structure of titanium aluminum nitride form an atomic-level coherent interface, which inhibits crack propagation through an interface stress transmission mechanism, improves the fracture toughness of the coating layer, the lanthanum magnesium aluminum spinel and the cobalt-based alloy form a continuous gradient transition structure, effectively relieving the thermal stress concentration at the coating-substrate interface, improving the thermal shock cycle number, the layered crystal structure of hexagonal boron nitride provides self-lubrication function, and at the same time forms a lubricating film-reinforced phase composite system with SiC nanoparticles, which reduces the wear rate while enhancing the anti-washing ability.

[0055] The above shows and describes the basic principles, main features and advantages of the application. Those skilled in the art should understand that the application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the application. Without departing from the spirit and scope of the application, various changes and improvements can be made to the application, and these changes and improvements all fall within the scope of the claimed application. The scope of protection of the application is defined by the appended claims and their equivalents.

Claims

1. A high-temperature coating for steam turbine blades, characterized in that, The composition includes the following components in the indicated mass ratios: 20-30 parts of yttrium-stabilized zirconium oxide (Y-ZrO2), 15-20 parts of titanium aluminum nitride (TiAlN), and lanthanum magnesium aluminum spinel (LaMgAl). 11 O 19 10-15 parts, nano-cerium oxide CeO2 5-10 parts, cobalt-based alloy Co-Cr-Al-Y 10-15 parts, rare earth element mixture 1-5 parts, hexagonal boron nitride h-BN 5-10 parts, SiC nanoparticles 5-10 parts, chromium carbide Cr3C2 2-5 parts.

2. The ultra-high temperature coating for turbine blades according to claim 1, characterized in that: The composition includes the following components by mass ratio: 25 parts of yttrium-stabilized zirconium oxide (Y-ZrO2), 18 parts of titanium aluminum nitride (TiAlN), and lanthanum magnesium aluminum spinel (LaMgAl). 11 O 19 12 parts, 8 parts of nano-cerium oxide CeO2, 12 parts of cobalt-based alloy Co-Cr-Al-Y, 3 parts of rare earth element mixture, 8 parts of hexagonal boron nitride h-BN, 7 parts of SiC nanoparticles, and 3 parts of chromium carbide Cr3C2.

3. The ultra-high temperature coating for turbine blades according to claim 1, characterized in that: The yttrium-stabilized zirconium oxide contains 8% Y2O3 and has a particle size of 1-5 μm; the titanium aluminum nitride contains 60-70% Al and has a particle size ≤10 μm.

4. The ultra-high temperature coating for turbine blades according to claim 1, characterized in that: The atomic ratio of La:Mg:Al in the lanthanum magnesium aluminum spinel is 1:1:11; the nano-cerium oxide has a particle size of 5-10 nm and a purity of ≥99.9%; and the mass ratio of Co:Cr:Al:Y in the cobalt-based alloy is 70:20:8:

2.

5. The ultra-high temperature coating for turbine blades according to claim 1, characterized in that: In the rare earth element mixture, the mass ratio of La:Ce:Nb is 4:4:2; the purity of the hexagonal boron nitride is ≥98%, and the thickness of the sheets is ≤1μm.

6. A method for preparing an ultra-high temperature coating for steam turbine blades, applied to the ultra-high temperature coating for steam turbine blades described in any one of claims 1-5, characterized in that, Includes the following steps: S1: Hydrogen reduction treatment of cobalt-based alloys, and ball milling of titanium aluminum nitride and chromium carbide under argon gas. S2: Add each component to anhydrous ethanol according to the ratio, disperse by ultrasonication, ball mill, and spray dry to obtain spherical composite powder; S3: The composite powder is sprayed onto the turbine blades using a supersonic flame spraying method to form a coating. S4: Vacuum nitriding and gradient annealing are performed on the coating to cure it.

7. The method for preparing an ultra-high temperature coating for turbine blades according to claim 6, characterized in that: In step S1, the cobalt-based alloy powder is subjected to hydrogen reduction treatment at 600°C for 2 hours, with the H2 flow rate controlled at 2 L / min. The titanium aluminum nitride and chromium carbide are ball-milled under argon for 4 hours, with the ball-to-material ratio controlled at 8:1 and the rotation speed at 450 rpm.

8. The method for preparing an ultra-high temperature coating for turbine blades according to claim 6, characterized in that: In step S2, each component is added to anhydrous ethanol according to the specified ratio, ultrasonically dispersed for 2 hours, ball-milled for 8 hours, and spray-dried to obtain spherical composite powder with a particle size distribution of 20-80 μm and a flowability of ≤25s / 50g.

9. The method for preparing an ultra-high temperature coating for turbine blades according to claim 6, characterized in that: In S3, when using supersonic flame spraying, the spraying fuel is a C3H6 / O2 mixture with a flow ratio of 1:1.2, the fuel flow rate is controlled at 250L / h, the spraying distance is 300mm, the substrate is preheated to 500℃, and the coating thickness after spraying is controlled at 150±15μm.

10. The method for preparing an ultra-high temperature coating for turbine blades according to claim 6, characterized in that: In S4, during the vacuum nitriding process, the temperature is controlled at 1050℃ for 3 hours, and the nitrogen pressure is controlled at 0.5MPa. The gradient annealing includes the following stages: treatment at 1200℃ for 1 hour under argon protection; treatment at 800℃ for 4 hours under vacuum; and air cooling to room temperature.

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