Method for repairing hot corrosion of a single crystal gas turbine working blade airfoil

Abstract

This invention discloses a method for repairing hot corrosion on the blade of a single-crystal gas turbine, comprising a process for removing the hot corrosion layer and a process for spraying a repair coating. In the process of removing the hot corrosion layer, high-pressure water jet is used to locally remove the hot corrosion layer on the blade. In the process of spraying the repair coating, a spray gun is used to spray the coating onto the area on the blade where the hot corrosion layer was removed. During the spraying process, the blade remains stationary while the spray gun moves horizontally. The use of high-pressure water jet technology to locally remove the hot corrosion layer on the surface of the working blade, and the optimized spraying parameters ensure that no damage is caused to the original coating and substrate, while reducing blade repair costs while ensuring thorough coating removal. By improving the spraying method and related parameters of supersonic flame spraying of nickel-cobalt-chromium-aluminum-yttrium-tantalum coatings, the coating thickness in each hot corrosion area can be effectively controlled within the range of 0.02-0.07 mm, while ensuring the antioxidant and corrosion resistance of the repair coating, meeting the blade design requirements, and ensuring that the blade returns to its pre-repair condition.

Description

Technical Field

[0001] This invention relates to the field of aero-engine blade repair technology, specifically to a method for repairing hot corrosion on the blade body of a single-crystal gas turbine. Background Technology

[0002] Gas turbine blades are an important component of gas turbines. The base material of the blades is mostly single crystal material, hence the name single crystal gas turbine blades. In order to protect the base material, improve the service life of the blades, and reduce costs, a high-temperature and hot corrosion resistant protective coating needs to be sprayed on the surface of the blade.

[0003] The gas turbine blades of a certain engine mass-produced unit are coated with a high-temperature corrosion resistant nickel-cobalt-chromium-aluminum-yttrium-tantalum (NiCoCrAlYTa) coating using vacuum plasma spraying. However, due to prolonged operation in harsh environments of high temperature, high speed, and high pressure, significant hot corrosion may occur on the blade surface coating. Inspection of gas turbine blades disassembled from engines undergoing repair revealed a significant hot corrosion layer on the blade surface. This layer is primarily concentrated near the blade root on the exhaust edge of the blade face (see attached manual). Figure 7 ) and the part of the blade back near the blade root on the air intake side (see instruction manual). Figure 8 The corrosion layer at the leaf base is deeper, while the corrosion layer on the underside of the leaf is relatively lighter.

[0004] During long-term service, the surface of gas turbine blades is subjected to high-temperature and high-pressure airflow, and the area and depth of the hot corrosion layer continuously increase. When the internal stress of the hot corrosion layer exceeds the bonding strength, the hot corrosion layer will crack and peel off, causing the blade substrate in this area to be exposed to the harsh environment and accelerating the failure of the blade.

[0005] However, gas turbine blades are valuable, and to extend their service life, it is necessary to remove the hot corrosion layer on the blade surface and recoat it with a nickel-cobalt-chromium-aluminum-yttrium-tantalum coating. Conventional methods for removing the hot corrosion layer on blade surfaces include sandblasting, mechanical polishing, and chemical removal. Sandblasting has the disadvantage of being difficult to control and prone to removing excessive amounts of substrate; mechanical polishing suffers from uneven removal; and chemical removal methods are characterized by low efficiency, environmental restrictions, and difficulties in protecting the substrate.

[0006] Furthermore, for gas turbine blades after the hot corrosion layer has been removed, a nickel-cobalt-chromium-aluminum-yttrium-tantalum coating needs to be recoated onto the hot corrosion areas. Firstly, as an anti-oxidation coating, the fewer oxides within the coating structure, the better its corrosion resistance; however, current coating processes cannot achieve this balance. Secondly, due to the small size and curved structure of the blades, controlling the thickness of the recoated layer on the corroded areas is difficult.

[0007] Patent CN102817000B discloses a method for repairing the anti-oxidation and corrosion coating on high-pressure turbine blades. First, a wet sandblasting method is used to treat the corroded coating on the blades. Then, the blades with the original coating removed are ultrasonically cleaned and immersed in acetone, followed by drying, visual inspection, and weighing. Next, an AlSiY coating is applied to the pre-treated blades using a vacuum arc plating method. The coated blades undergo vacuum heat treatment. Finally, the vacuum heat-treated blades are subjected to wet sandblasting treatment to obtain the final product.

[0008] The aforementioned patent also removes and repairs hot-corroded coatings, but it removes the entire coating on the blade and then re-sprays the repair coating. Furthermore, the method used to remove the hot-corroded layer is the aforementioned sandblasting removal, which is difficult to control and easily removes too much substrate. In addition, the thickness of the corrosion coating is not considered in the repair of the corrosion coating in this patent. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a method for repairing hot corrosion of single crystal gas turbine blades by locally removing the original corroded coating and effectively controlling the thickness of the new coating.

[0010] The objective of this invention is achieved through the following technical solution:

[0011] A method for repairing hot corrosion on a single-crystal gas turbine blade includes a process for removing the hot corrosion layer and a process for spraying a repair coating. In the process of removing the hot corrosion layer, high-pressure water jet is used to locally remove the hot corrosion layer on the blade, and it is necessary to check whether the hot corrosion layer on the blade has been completely removed. In the process of spraying the repair coating, the blade is horizontally clamped, and after the hot corrosion layer area of ​​the blade is roughened by sandblasting, a spray gun is used to spray the coating onto the area of ​​the blade where the hot corrosion layer has been removed. During the spraying process, the blade is in a stationary state, and the spray gun moves horizontally in an attitude perpendicular to the hot corrosion layer area of ​​the blade to spray.

[0012] Furthermore, in the process of removing the hot corrosion layer, high-pressure water is used to remove the hot corrosion layer from multiple areas one by one.

[0013] Furthermore, the high-pressure water jet pressure is 2500–3000 bar, the high-pressure water jet nozzle rotation speed is 900–1100 RPM, and the jet distance is 30–50 mm.

[0014] Furthermore, in the spraying repair coating process, a supersonic flame spraying process is used to spray the hot corrosion layer area of ​​the blade.

[0015] Furthermore, the spraying process parameters are as follows:

[0016] Gas pressure: Air 8±2 bar; O2 11±2 bar; H2 11±2 bar;

[0017] Gas flow rates: Air 280±30 NLPM; O2 200±10 NLPM; H2 540±10 NLPM; Carrier gas 12.5±1 NLPM;

[0018] The spray distance is 210±20mm;

[0019] The powder feeding rate is 35±5g / min.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] High-pressure water jet technology is used to locally remove the hot corrosion layer on the surface of the working blade. The specially designed jetting parameters ensure that no damage is caused to the original coating and substrate, and reduce the cost of blade repair while ensuring that the coating is completely removed.

[0022] By improving the spraying method and related parameters of supersonic flame spraying of nickel-cobalt-chromium-aluminum-yttrium-tantalum coatings, the coating thickness in each hot corrosion zone can be effectively controlled within the range of 0.02-0.07 mm, while ensuring the anti-oxidation and corrosion performance of the repair coating, meeting the blade design requirements, and ensuring that the blade reaches the state before spraying and repair. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the special fixture described in Example 1;

[0024] Figure 2 This is a top view of the special fixture described in Example 1;

[0025] Figure 3 This is a schematic diagram illustrating the separation of the surface coating on a blade when the entire blade is sprayed using a traditional rotary spraying method.

[0026] Figure 4 This is a schematic diagram showing that the coating on the blade surface did not separate after the coating was sprayed using a non-rotating method in Example 1.

[0027] Figure 5 This is a schematic diagram of the protective clamp in Example 1 (including the cylindrical base);

[0028] Figure 6 This is a schematic diagram of the protective clamp in Example 1 (excluding the cylindrical base);

[0029] Figure 7 The surface morphology of the thermal corrosion layer on the air venting edge of the blade near the leaf root;

[0030] Figure 8The surface morphology of the thermal corrosion layer on the air intake side of the blade near the blade root. Detailed Implementation

[0031] To clearly illustrate the technical features of this solution, the following detailed description, in conjunction with the accompanying drawings, will explain the technical solution in detail.

[0032] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below.

[0033] Furthermore, it should be understood in the description of this application that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0034] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0035] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0036] Example 1

[0037] A method for repairing hot corrosion on the blade of a single-crystal gas turbine requires removing the hot corrosion layer and recoating the hot corrosion layer area with a repair coating. The process for removing the hot corrosion layer is as follows: cleaning → clamping → coating removal → cleaning → inspection.

[0038] S11. Cleaning: Clean the blade surface with acetone or anhydrous ethanol and store it in a clean work station.

[0039] S12. Clamping: Use a special clamp to clamp the blade to prevent damage to the part. Use a three-jaw chuck to clamp the part on the equipment turntable. The equipment described here is the subsequent high-pressure water jet equipment.

[0040] S13. Coating Removal: For multiple areas on the blade with hot corrosion layers, high-pressure water jet is used to remove them. The removal method is to remove the coating layer area by area. For example, if there are only two areas with hot corrosion layers, remove the coating layer from one area first, and then remove the coating layer from the other area. During the removal process, observe whether the equipment is abnormal.

[0041] S14. Cleaning: Rinse off excess material from the blade surface with water. Check whether the hot corrosion layer in the relevant area of ​​the blade surface has been completely removed. If there is residual corrosion, repeat the removal process until the corrosion layer is completely removed. Use compressed air to blow dry the moisture on the blade surface, or place it in an oven at 60℃~90℃ for drying.

[0042] S15. Inspection: Visually inspect the hot corrosion layer in the relevant areas of the blade. There should be no obvious residual corrosion (black oxide) on the surface. Use a combination of visual inspection and magnification. After visual inspection, use a 5-10x magnifying glass for a second inspection. After all the hot corrosion layer on the surface of the blades in the same batch has been removed, select one blade for cross-section inspection to check for residual corrosion.

[0043] Because turbine blades are small, while high-pressure water jets have high pressure, large flow area, and strong impact force, specialized clamps are introduced in S12 to effectively secure the blades and protect the blade tenons, thus ensuring the effective removal of the hot corrosion layer from the blade surface. Specifically, for example... Figure 1 and Figure 2 As shown, the special fixture includes a base 11 (the base is clamped by the three-jaw chuck described above). Two opposing side plates 13 are fixed on the base with bolts 12. A first clamping plate 14 and a second clamping plate 15 are clamped between the two side plates 13. The first clamping plate 14 and the second clamping plate 15 are opposite to each other and arranged perpendicular to the two side plates 13. The two ends of the first clamping plate 14 are respectively bolted to the two side plates 13. The surface of the second clamping plate 15 is connected to the surface of the first clamping plate 14 by a screw 16. Since the position of the first clamping plate 14 is fixed, the second clamping plate 15 can be moved closer to or away from the first clamping plate 14 by rotating the screw 16. When the first clamping plate 14 and the second clamping plate 15 are close together, they are used to clamp the two sides of the blade tenon. In order to prevent damage to the tenon, soft pads 17 are attached to the surfaces of the first clamping plate 14 and the second clamping plate 15 facing the blade clamping area. The soft pads are preferably made of rubber. Two side plates 13, a first clamping plate 14, and a second clamping plate 15 enclose a blade clamping area. Two support rods 18 extend from the first clamping plate 14 toward the blade clamping area, contacting the bottom of the blade tenon and providing overall support for the blade. These two support rods are evenly distributed at the bottom of the tenon, jointly supporting the blade. Each of the two side plates 13 extends toward the blade clamping area, abutting against both ends of the blade tenon to hold it in place. The clamping rods are horizontally arranged, and the two clamping rods do not need to be aligned; their staggered arrangement better maintains the clamping of the blade. The support rods 18 and clamping rods 19 together achieve the horizontal and vertical positioning of the blade.

[0044] High-pressure water jetting refers to pressurizing water (the medium) to a certain pressure (generally greater than 100MPa) using a booster pump, and then spraying the water at a certain speed from a nozzle. As the spray gun rotates, the nozzle seat installed on it causes the water flow to form a spiral shape, creating a special cleaning effect similar to a milling cutter. The main parameters of high-pressure water jetting equipment include spray pressure, nozzle rotation speed, and spray distance. To ensure that the high-pressure water completely removes the hot corrosion layer on the blade surface without damaging the original coating and substrate, a protective plate is used to shield the areas of the blade where the hot corrosion layer does not need to be removed before spraying (the protective plate can be simply made of stainless steel sheet, tied to the blade with wire). The process parameters are shown in the table below during spraying.

[0045] Water pressure (bar) Nozzle rotation speed (RPM) Spray distance (mm) 2500-3000 800-1200 30

[0046] In this embodiment, the hot corrosion layer on the blade surface is mainly concentrated in the area near the exhaust edge of the blade basin and the area near the intake edge of the blade back. Since the hot corrosion layer areas are relatively concentrated and the hot corrosion layer positions are not on the same annular surface, a fixed-point area-by-area removal method is selected for high-pressure water spraying, taking into account the removal efficiency. The spray gun is moved horizontally to spray high-pressure water in the hot corrosion layer areas of the blade basin and the blade back.

[0047] After removing the hot corrosion layer using high-pressure water, a visual inspection of the corroded area revealed slight depressions in the blade's hot corrosion zone, with most of the surface appearing grayish-white. At this point, no obvious corrosion layer remained. Magnified observation showed that the hot corrosion layer in both areas had been removed, exposing a smooth, silvery-white substrate. A section of the blade with the removed hot corrosion layer was then examined, revealing no residual hot corrosion layer. A clear step was visible at the transition area between the corrosion pit edge and the original coating, and the high-pressure water erosion did not damage the original coating. The corrosion pits were slight depressions, with a maximum depth of approximately 0.2 mm. The remaining surfaces were intact, with no abnormal damage morphology observed. Fluorescent examination of the substrate surface showed no cracks in the area where the hot corrosion layer was removed, and the surrounding coating remained intact. Further examination of the blade's recrystallization revealed no recrystallization on the substrate surface. The blade was first placed in a vacuum heat treatment furnace for diffusion treatment at a temperature of 1000–1100℃ for 4–7 hours. After cooling to room temperature in the furnace, a section metallographic examination was performed, revealing no recrystallization on the blade substrate surface.

[0048] For areas where the hot-corrosion layer has been removed, a nickel-cobalt-chromium-aluminum-yttrium-tantalum coating is re-sprayed using a supersonic flame. The specific process flow is as follows:

[0049] Cleaning → Sandblasting protection → Sandblasting → Spray coating protection → Spray coating → Cleaning → Inspection.

[0050] S21. Cleaning: Soak the leaves in acetone, then use a soft brush to clean the leaf surface and tips.

[0051] S22. Sandblasting protection: Protective tape is used to protect the blade tenon and the underside of the rim plate to prevent sandblasting from affecting the tenon area.

[0052] S23. Sandblasting: Sandblasting is performed on the corroded area and surrounding area to roughen the surface and further clean the surface. The sandblasting time should be controlled between 90s and 120s. Focus on sandblasting the corroded area. After sandblasting is completed, remove the protective tape from the side of the blade edge plate.

[0053] S24. Spray coating protection: The blade is horizontally clamped on a spray coating protection fixture, and its protective effect is checked.

[0054] S25. Spraying: Spray the hot corrosion layer area of ​​the blade according to the set supersonic flame spraying process parameters.

[0055] S26. Cleaning: Clean the surface of the sprayed blades as necessary, and no excess material should be left behind.

[0056] Since the purpose of the coating applied to the hot-corrosion area of ​​the blade is to improve its oxidation resistance and slow down the rate of heat corrosion, the less oxides within the coating structure, the better its oxidation and corrosion resistance. Therefore, it is necessary to optimize and adjust the main spraying process parameters (oxygen, hydrogen, spraying distance, etc.) when applying the coating to the blade. The optimized spraying process parameters in this embodiment are as follows:

[0057]

[0058] Before this optimization, the process parameters for blade coating were as follows:

[0059]

[0060] This optimization primarily modulates the coating's microstructure by altering three parameters: O2 flow rate, H2 flow rate, and spray distance. Reducing the hydrogen-oxygen ratio lowers the oxide content in the microstructure, while the carefully chosen H2 flow rate avoids the risk of unmelted spherical particles forming within the coating and affecting coating quality when hydrogen levels are too low. Based on this appropriate hydrogen-oxygen flow rate ratio, the overall gas flow rate decreases, allowing for a simultaneous reduction in spray distance to ensure the concentrated flame beam is applied directly to the part.

[0061] When applying a repair coating, if the traditional rotary spraying method is used to spray the entire blade body, the width of the supersonic flame can cover two areas of hot corrosion. The hot corrosion layer of the blade and its axial annular surface are covered with a re-sprayed coating. Metallographic examination shows that the coating at the hot corrosion sites is continuous and intact, without cracks or separation. However, the coating is relatively thicker in the middle of the blade's blade surface, and there is obvious separation of the coating. Figure 3 As shown. In addition, due to the small blade area and large blade curvature, especially in the middle of the blade basin, there is powder flame reflection during spraying, which also leads to uneven distribution of the blade coating thickness in the circumference. The coating thickness is thicker in the middle of the blade basin, and the adhesion of the coating is relatively poor, which easily leads to coating separation.

[0062] To better control the coating thickness and address the issue of interface separation caused by a thicker coating in the center of the blade, this embodiment further improves the spraying method. During spraying, the blade does not rotate; that is, the blade remains stationary. The spray gun moves horizontally to spray the two hot-corrosion layer areas and the edge areas. Specifically, the spray gun moves horizontally perpendicular to the hot-corrosion layer areas of the blade. Other areas are allowed to be sprayed with a nickel-cobalt-chromium-aluminum-yttrium-tantalum coating without supersonic flame, ensuring that the hot-corrosion layer areas and their circumferential surfaces are coated. This method of spraying without blade rotation, relying solely on the movement of the spray gun, effectively controls the thickness of the recoated coating.

[0063] Furthermore, during the spraying process, the relative positions of the blades and the spray gun can be adjusted according to the actual situation to avoid the flame sweeping onto the central R-angle of the blade basin, causing coating accumulation and interface separation. Simultaneously, the flame needs to completely cover the corrosion pit area. After determining the relative positions, the robotic arm program is fixed to ensure consistent spraying areas each time.

[0064] Metallographic examination of the blades coated with the repair coating revealed that the coating at the hot corrosion sites was continuous and intact, without cracks or separation. The coating at the edges of the hot corrosion pits showed a smooth transition. Figure 4 As shown.

[0065] To verify the effectiveness of the above spraying method, multiple blades were sprayed with the same parameters. The results showed that the coating thickness on the exhaust side of the blade face, where heat corrosion occurred, was 0.025–0.070 mm, and on the intake side of the blade back, where heat corrosion occurred, the coating thickness was 0.025–0.055 mm. The overall blade coating thickness remained stable within the range of 0.02–0.07 mm, and the coating was continuous, intact, and free of cracks or separation. Furthermore, the coating thickness distribution could be further adjusted by changing the spray gun's movement speed and the number of spray passes.

[0066] During the spraying process, two hot-corrosion areas need to be sprayed separately. When spraying the hot-corrosion area near the inlet edge of the blade back, the flame width is relatively large and will cover the hot-corrosion area of ​​the blade head, making it difficult to control the coating thickness. Therefore, protective clamps are needed to protect the blade head surface. Specifically, for example... Figure 5 and Figure 6As shown, the protective clamp in S24 includes a blade tenon clamping device and a baffle 21 detachably connected to the clamping device. The clamping device includes a cylindrical base 22 and two parallel side panels 23 fixed on the cylindrical base. The cylindrical base 22 is used to achieve angular and height positioning of the blade. The two side panels 23 function as the first and second clamping plates in the aforementioned special clamp, used to clamp both sides of the blade tenon. A stop block 24 is respectively attached to both ends of the side panel 23. Bolts are installed on the stop blocks 24. After the bolts are screwed into the stop blocks 24, they abut against both ends of the blade tenon to clamp the blade. The baffle 21 is adapted to the surface structure of the blade's blade surface. The baffle 21 is used to cover the blade surface when the repair coating is sprayed on the back side of the blade. The baffle 21 is installed on the side panel 23 by bolts.

[0067] When spraying the hot corrosion layer area on the exhaust side of the blade basin, the baffle must be removed. When spraying the hot corrosion layer area on the intake side of the blade back, the baffle must be installed to prevent spraying onto the hot corrosion layer area of ​​the blade basin.

[0068] Using the above-mentioned protective clamps can ensure that the blades can be positioned in both angular and height directions, and effectively control the coating thickness of the two hot corrosion layer areas.

[0069] Example 2

[0070] The difference between this embodiment and Embodiment 1 is that the spraying is performed using the process parameters shown in the table below:

[0071] Water pressure (bar) Nozzle rotation speed (RPM) Spray distance (mm) 2500-3000 800-1200 40

[0072] Example 3

[0073] The difference between this embodiment and Embodiment 1 is that the spraying is performed using the process parameters shown in the table below:

[0074] Water pressure (bar) Nozzle rotation speed (RPM) Spray distance (mm) 2500-3000 800-1200 50

[0075] Obviously, the above embodiments are merely examples to clearly illustrate the technical solutions of the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for repairing hot corrosion on the blade of a single-crystal gas turbine, comprising a process for removing the hot corrosion layer and a process for spraying a repair coating, characterized in that, In the process of removing the hot corrosion layer, a protective plate is used to shield the areas of the blade where the hot corrosion layer does not need to be removed. Then, high-pressure water jet is used to locally remove the hot corrosion layer on the blade, and it is necessary to check whether the hot corrosion layer on the blade has been completely removed. The high-pressure water jet pressure is 2500-3000 bar, the rotation speed of the high-pressure water jet nozzle is 900-1100 RPM, and the spray distance is 30-50 mm. In the process of spraying the repair coating, after the hot corrosion layer area of ​​the blade is roughened by sandblasting, the blade is clamped with a protective clamp. When spraying the hot corrosion layer area on the exhaust side of the blade basin, the baffle on the protective clamp is removed, and the coating is sprayed onto the hot corrosion layer area on the blade basin with a spray gun. When spraying the hot corrosion layer area on the inlet side of the blade back, the baffle is installed, and the coating is sprayed onto the hot corrosion layer area on the blade back with a spray gun. During the spraying process, the blade is stationary, and the spray gun moves horizontally in a posture perpendicular to the hot corrosion layer area of ​​the blade to spray. The protective clamp includes a blade tenon clamping device and a baffle detachably connected to the clamping device. The baffle is adapted to the surface structure of the blade's blade surface. The baffle is used to cover the surface of the blade surface when the repair coating is sprayed on the back side of the blade. In the process of removing the hot corrosion layer, a clamp is used to clamp the blade. The clamp includes a base, on which two opposing side plates are fixedly mounted. A first clamping plate and a second clamping plate are clamped between the two side plates. The first clamping plate and the second clamping plate are opposite to each other and arranged perpendicular to the two side plates. The two ends of the first clamping plate are respectively connected to the two side plates. The second clamping plate and the first clamping plate are connected by a screw. By rotating the screw, the first clamping plate and the second clamping plate can be moved closer or further apart. When the first clamping plate and the second clamping plate are close together, they are used to clamp the two sides of the blade tenon. The two side plates, the first clamping plate and the second clamping plate enclose a blade clamping area. At least two support rods extend from the first clamping plate toward the blade clamping area, which contact the bottom of the blade tenon and support the blade. At least one clamping rod extends from each of the two side plates toward the blade clamping area, which abuts against the two ends of the blade tenon to clamp the blade tenon. In the aforementioned spraying repair coating process, a nickel-cobalt-chromium-aluminum-yttrium-tantalum coating is applied to the hot-corrosion layer area of ​​the blade using a supersonic flame spraying process; the spraying process parameters are as follows: Gas pressure: Air 8±2 bar; O2 11±2 bar; H2 11±2 bar; Gas flow rates: Air 280±30 NLPM; O2 200±10 NLPM; H2 540±10 NLPM; Carrier gas 12.5±1 NLPM; The spray distance is 210±20mm; The powder feeding rate is 35±5g / min.

2. The method for repairing hot corrosion of single-crystal gas turbine blades according to claim 1, characterized in that, In the process of removing the hot corrosion layer, high-pressure water is used to remove the hot corrosion layer from multiple areas one by one.

3. The method for repairing hot corrosion of single-crystal gas turbine blades according to claim 1, characterized in that, Soft pads are attached to the surfaces of the first and second clamping plates facing the blade clamping area.

4. The method for repairing hot corrosion of single-crystal gas turbine blades according to claim 1, characterized in that, In the process of removing the hot corrosion layer, the inspection of whether the hot corrosion layer has been completely removed includes visual inspection and magnification inspection. The magnification used for the magnification inspection is 5 to 10 times.

5. The method for repairing hot corrosion of single-crystal gas turbine blades according to claim 1, characterized in that, The sandblasting roughening time should be controlled between 90s and 120s.

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