Repair method of aero-engine blade

Abstract

The invention belongs to the technical field of aero-engine repairing, and discloses an aero-engine blade repairing method which comprises the steps that a powder material used for repairing an aero-engine blade is deposited on a to-be-repaired part of a to-be-repaired blade through a laser-assisted cold spraying method, and a laser-assisted cold spraying deposition repairing layer is formed on the surface of the to-be-repaired part. And the laser-assisted cold spraying deposition repairing layer is machined to the original size precision and surface roughness of the blade to be repaired, then laser shock is adopted for enhancing treatment on the laser-assisted cold spraying deposition repairing layer, and repairing is completed. The powder material for repairing the aero-engine blade is micron titanium alloy powder. According to the invention, a composite repair process combining laser-assisted cold spraying and laser shock peening is creatively adopted, so that high-quality additive repair and fatigue performance enhancement of a damaged area are realized, and the safety and reliability of the blade in the subsequent service process are guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine repair technology, and specifically relates to a method for repairing aero-engine blades, taking into account the corrosion, wear and fatigue performance of the repaired blades, the density of the repair layer, and the bonding strength. Background Technology

[0002] Aero-engines are the "heart" of modern aircraft, and blades, as one of the most critical core components, are complex in structure, operate under harsh conditions, and require extremely high manufacturing precision, determining the engine's performance and lifespan. Aero-engine blades typically operate for extended periods in extreme environments such as high temperature, high pressure, high speed rotation, and strong corrosion, making them highly susceptible to surface damage and structural degradation. Depending on the service environment and material properties, common blade damage types include fatigue cracks, cavitation pits, wear pits, corrosion pits, and edge defects. These microscopic and macroscopic defects can lead to a decrease in local blade strength, changes in vibration modes, and dynamic imbalance, and in severe cases, even cause the entire engine to fail, resulting in major safety accidents. Therefore, the efficient repair and remanufacturing of aero-engine blades has become an important research direction in the field of aerospace maintenance engineering.

[0003] Traditional blade repair methods mainly include brazing, laser cladding, plasma spraying, and electron beam melting. These methods typically rely on high-energy beams or high-temperature heating processes to melt and redeposit materials. While they offer high deposition efficiency and a certain level of repair precision, they also face several limitations. First, significant heat input can induce metallurgical defects such as coarsening of the metal structure, compositional segregation, and even hot cracking, especially in heat-sensitive materials like high-strength aluminum alloys and titanium alloys. Second, the high-temperature process often leads to the accumulation of substantial residual tensile stress in the repair area, becoming a source of fatigue crack initiation and significantly reducing the fatigue life and service reliability of aero-engine blades. Furthermore, traditional cladding-based repair processes have significant shortcomings in dimensional control and adaptability to irregularly shaped structural parts, limiting their application and promotion in the repair of complex aero-engine blades. Summary of the Invention

[0004] In view of the problems existing in the prior art, the purpose of this invention is to provide a method for repairing aero-engine blades. This invention innovatively adopts a composite repair process that combines laser-assisted cold spraying and laser shock peening to achieve high-quality additive repair and fatigue performance enhancement of the damaged area, ensuring the safety and reliability of the blade in subsequent service.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for repairing aero-engine blades includes the following steps: Powder material for repairing aero-engine blades is deposited on the part of the blade to be repaired using a laser-assisted cold spraying method, forming a laser-assisted cold spraying deposited repair layer on the surface of the part to be repaired. The laser-assisted cold spraying deposited repair layer is then processed to the original dimensional accuracy and surface roughness of the blade to be repaired. Finally, the laser-assisted cold spraying deposited repair layer is reinforced by laser shock, and the repair is completed. The powder material used to repair aero-engine blades is micron-sized titanium alloy powder.

[0006] Preferably, the micron-sized titanium alloy powder is spherical Ti6Al4V powder.

[0007] Preferably, the particle size of the micron-sized Ti6Al4V powder is less than 100 μm.

[0008] Preferably, the thickness of the laser-assisted cold spray deposition repair layer is 1900~2100μm.

[0009] Preferably, when the powder material used to repair aero-engine blades is deposited on the area to be repaired on the blade using a laser-assisted cold spraying method: The parameters for laser-assisted cold spraying include: carrier gas pressure of 1.0–3.0 MPa, spraying distance of 15–30 mm, spray gun moving speed of 50–80 mm / s, spraying temperature of 400–600℃, powder feeding speed of 0.5 r / min–2.0 r / min, and laser power of 1200 W–2000 W. Preferably, when laser shock is used to enhance the laser-assisted cold spray deposition repair layer, the laser shock enhancement parameters include: laser energy of 3 J ~ 12 J, pulse width of 10 ns ~ 30 ns, spot diameter of 3 mm ~ 6 mm, and spot overlap rate of 45% ~ 55%.

[0010] Preferably, the damage type of the part of the blade to be repaired includes one or more of the following: surface fatigue cracks, cavitation pits, wear pits, corrosion pits, and edge defects.

[0011] Preferably, the repair method of the present invention further includes a pretreatment process for the part of the blade to be repaired, including: The surface of the part to be repaired on the blade is successively sanded with water sandpaper, ultrasonically cleaned and sandblasted, and then powder material is deposited by laser-assisted cold spraying. Among them, the sandblasting treatment makes the surface roughness of the part to be repaired reach Ra60μm~80μm. During the sandblasting treatment, the sand is brown corundum with a particle size of 400μm~700μm, and the compressed air pressure during sandblasting is 0.5 MPa~0.7MPa.

[0012] Preferably, after processing the laser-assisted cold spray deposition repair layer to the original dimensional accuracy and surface roughness of the blade to be repaired, the blade to be repaired with the laser-assisted cold spray deposition repair layer is ultrasonically cleaned and dried using ethanol as a solution; after drying, the laser-assisted cold spray deposition repair layer is then enhanced by laser shock.

[0013] Preferably, the repair blade is made of a high-temperature alloy material, including titanium alloy, cobalt-based high-temperature alloy, or nickel-based high-temperature alloy.

[0014] The present invention has the following beneficial effects: This invention relates to a method for repairing aero-engine blades that combines laser-assisted cold spraying with laser shock blasting, offering advantages such as low heat input, high bonding strength, and strong microstructural stability. By using laser assistance to soften the sprayed particles and improve deposition efficiency, the bonding force between the repair layer and the substrate is effectively enhanced. Simultaneously, it avoids problems such as melting, microstructural changes, and thermal damage associated with high-energy beam repair technologies like laser cladding, maintaining the integrity of the original composition and microstructure of the substrate and significantly improving the safety and applicability of the repair process. Furthermore, this invention introduces deep residual compressive stress on the surface of the repair layer through laser shock blasting, optimizing the stress field distribution in the repair area and significantly improving the blade's resistance to fatigue cracking and service life. The overall process has minimal heat-affected zone and strong adaptability, making it particularly suitable for repairing aero-engine blades with complex morphologies and high-performance requirements, possessing broad engineering application prospects and industrialization value. Attached Figure Description

[0015] Figure 1 This is a process flow diagram of the method for repairing aero-engine blades in an embodiment of the present invention; Figure 2 This is a schematic diagram of the laser-assisted cold spraying equipment used in the embodiments of the present invention; Figure 3 This is a schematic diagram of the laser shock peening device in an embodiment of the present invention; Figure 4 Micrograph of Ti6Al4V powder used in Example 1 of this invention; Figure 5 Micrograph of Ti6Al4V powder used in Example 2 of this invention; Figure 6 Micrograph of Ti6Al4V powder used in Example 3 of this invention; Figure 7 This is a microscopic morphology image (500x magnification) of the coating after repair in Example 1 of the present invention. Figure 8 This is a microscopic morphology image (1000x magnification) of the coating after repair in Example 2 of the present invention. Figure 9This is a microscopic morphology image (100x magnification) of the coating after repair in Example 3 of the present invention. Figure 10 This is a microscopic morphology image (50x magnification) of the coating after repair in Example 3 of the present invention.

[0016] In the figure, 1-mixing chamber, 2-laser, 3-nozzle, 4-laser beam, 5-thermometer, 6-coating, 7-substrate. Detailed Implementation

[0017] The present invention will now be described in conjunction with the accompanying drawings and embodiments. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0018] This invention provides a repair method for aero-engine blades, targeting typical damage forms that occur on aero-engine blades during service, such as surface fatigue cracks, cavitation pits, wear pits, corrosion pits, and edge defects.

[0019] This invention uses Ti6Al4V titanium alloy powder and a laser-assisted cold spraying method (the method employs, for example,...) Figure 2 The laser-assisted cold spraying equipment shown is the primary repair method. By controlling process parameters, a dense and highly bonded laser-assisted cold spraying deposition repair layer is prepared at the damaged site of titanium alloy (such as Ti6Al4V) blades. Furthermore, a laser shock treatment method has been developed, improving the bonding strength between the deposition repair layer (i.e., the laser-assisted cold spraying deposition repair layer) and the blade to be repaired, while also exhibiting corrosion resistance, wear resistance, and fatigue resistance. Simultaneously, the laser-assisted cold spraying method avoids the influence of thermal spraying and laser-directed energy deposition methods on the blade and repair layer microstructure. Moreover, the use of nitrogen as a protective gas in the laser-assisted cold spraying method reduces spraying costs. This improves the overall performance of the blade while reducing the operating costs of the aircraft.

[0020] The overall concept of this invention is as follows: Laser-assisted cold spraying is used to deposit powder material for repairing defects such as notches and cracks onto the surface of the aero-engine blade to be repaired, forming a laser-assisted cold sprayed repair layer on the blade surface. The repair layer on the repaired blade surface is then mechanically processed and polished to its original dimensional accuracy and surface roughness. The repaired area is then subjected to laser shock peening for enhancement, thereby obtaining a remanufactured repaired aero-engine blade with a dense surface, uniform structure, high bonding strength, and excellent corrosion, wear, and fatigue resistance.

[0021] Specifically, refer to Figure 1 The method for repairing aero-engine blades according to the present invention includes the following steps: Step 1: Place the micron-sized titanium alloy powder in a vacuum drying oven at 60–100°C and dry for 4–6 hours. The titanium alloy powder is Ti6Al4V powder, spherical in shape, as shown in the reference... Figures 4-6 .

[0022] Step 2 involves conducting a comprehensive flaw detection assessment of the serviced aero-engine blades using methods such as ultrasonic testing, eddy current testing, and X-ray non-destructive testing to determine the type and distribution of damage. Damage types include, but are not limited to, surface fatigue cracks, cavitation pits, wear pits, corrosion pits, and edge defects.

[0023] Step 3: During the flaw detection process, the location and size distribution information of defects are obtained through the data acquisition system, and high-resolution modeling and analysis of typical crack areas are carried out in combination with digital image analysis technology, which serves as the basis for subsequent repair path planning.

[0024] Step 4: Polish the surface of the crack or notch on the aero-engine blade with wet sandpaper until it is ready for repair. Specifically, the surface of the blade to be repaired is polished smooth with wet sandpaper of 80 grit, 200 grit, 1000 grit, 1500 grit and 2000 grit in sequence, and then ultrasonically cleaned. After cleaning, sandblasting is performed to make the surface roughness of the repaired part reach Ra60μm~80μm.

[0025] Step 5: Using laser-assisted cold spraying, the dried titanium alloy powder is sprayed onto the sandblasted notch surface according to the planned repair path, forming a laser-assisted cold spray deposition repair layer with a thickness of 2000±100μm; Figure 3 As shown, in this invention, a notch design of 90°~120° is adopted for notch pre-setting. SEM observation shows that the coating porosity is low and the coating quality is good at this notch. During the supersonic laser deposition process, the carrier gas pressure is 1.0~3.0MPa, the spraying distance is 15~30mm, the spray gun moving speed is 50~80mm / s, the spraying temperature is 400~600℃, the laser power is 500W~700W, and the powder feeding speed is 0.5 r / min~2.0 r / min.

[0026] The materials used for aero-engine blades are high-temperature alloys, including titanium alloys, cobalt-based high-temperature alloys, and nickel-based high-temperature alloys. This invention uses a Ti6Al4V titanium alloy blade as an example, but it is also applicable to aero-engine blades made of other materials mentioned above. Ti6Al4V titanium alloy is chosen because titanium alloys have advantages such as light weight, high specific strength, and good high-temperature performance. The carrier gas provided by the laser-assisted cold spraying method is nitrogen, helium, or compressed air. The sand used for sandblasting the Ti6Al4V titanium alloy surface is brown corundum with a particle size of 400-700 μm, and the sandblasting pressure is 0.6±0.1 MPa (where 0.6 is the set value, and 0.1 is the actual pressure deviation of the sandblasting equipment; in the following embodiments, the sandblasting pressure is expressed as the set value of 0.6, and its actual value is between 0.5-0.7 MPa during the sandblasting process).

[0027] Step 6, Laser Shock Pretreatment: The laser-assisted cold spray deposited repair layer is machined (e.g., by wire cutting). The surface of the laser-assisted cold spray deposited repair layer is polished with sandpaper of different grits. Then, the surface after supersonic laser deposition is polished with diamond polishing agent with a grit size of 0.5 microns to restore the aero-engine blade to its original size. The surface roughness after treatment is Ra0.2. Then, the aero-engine blade with the laser-assisted cold spray deposited repair layer is placed in an ultrasonic cleaning chamber for ultrasonic cleaning with ethanol as a solution. After cleaning, it is placed in a drying oven for drying at 80°C for 1 hour.

[0028] Step 7, Laser Shock Enhancement: Laser shock enhancement is used to enhance the pre-treated laser-assisted cold spray deposited repair layer and repair area. The laser shock parameters are as follows: laser energy is 3J~12J, pulse width is 10ns~30ns, spot diameter is 3mm~6mm, and spot overlap rate is 50%±5%.

[0029] Step 8, Friction Performance Test: The wear resistance of the repaired area surface was tested using a ball-disc friction and wear tester. The grinding material was a φ6mm Si3N4 ceramic ball, with a load of 10N, a sliding speed of 0.1m / s, a total stroke of 500m, and an ambient temperature of 25±2℃.

[0030] Step 9, Corrosion Performance Testing: A salt spray corrosion experiment was conducted, with continuous spraying of a 5wt% NaCl aqueous solution for 96 hours to evaluate the surface corrosion morphology of the repaired area. Simultaneously, electrochemical testing was performed using a three-electrode system. Potentiodynamic polarization curves were measured in a 3.5wt% NaCl aqueous solution, with a scan rate of 1 mV / s. The reference electrode was a saturated calomel electrode. In the process of repairing aero-engine blades, this invention requires the design of an appropriate powder particle size to achieve good results. The selection of powder particle size is related to the density of the material. Because laser-assisted cold spraying technology uses high-pressure gas as a power source, during the spraying process, the high-pressure gas reaches supersonic speed after passing through a Raoult tube. The supersonic gas forms a shock wave on the substrate surface, hindering particle impact on the substrate. Therefore, if the powder particle mass is too small, it will be difficult to overcome the shock wave, thus preventing effective deposition. However, if the powder particle size is too large, the gas acceleration effect will be poor, and the particle velocity will not meet the deposition requirements, also preventing effective deposition. In this invention, through reasonable experimental design, the particle size of titanium alloy powder was determined to be 0μm to 100μm.

[0031] In the implementation of the aero-engine blade repair and preparation method of the present invention, the powder material used to repair fatigue cracks, notches, and cavitation defects of aero-engine blades is laser-assisted cold-sprayed and deposited onto the surface of Ti6Al4V titanium alloy, thereby restoring the aero-engine blade to its original size. During the laser-assisted cold spraying process, the temperature is much lower than the melting temperature of the original powder material, which can effectively avoid the adverse effects of high temperature-induced oxidation, phase transformation, and thermal cracking. Furthermore, the high-speed spraying particles impacting the blade or already deposited particles can achieve a denser structure and better bonding strength.

[0032] Before laser-assisted cold spraying, the surface of the aero-engine blade to be repaired is sandblasted. Then, laser-assisted cold spray deposition repair is performed on the sandblasted surface. During sandblasting, the sand is brown fused alumina with a particle size of 400μm–700μm, and the compressed air pressure is 0.6±0.1MPa. Before preparing the repair layer, the surface of the blade is sandblasted to roughen the surface, increase the contact area between the particles and the substrate, and improve the bonding strength between the coating and the substrate. For aluminum alloy substrates, using brown fused alumina with a particle size of 400μm–700μm and a compressed air pressure of 0.6±0.1MPa during sandblasting effectively roughens the surface and results in high bonding strength between the coating and the substrate.

[0033] This invention provides a comprehensive powder selection process for repairing aero-engine blades, maximizing the functionality and potential of the original powder materials. This invention successfully completes the repair task of aero-engine blades, fully leveraging the advantages of laser-assisted cold spraying and providing a scientifically designed layout to repair aero-engine blades damaged by cracks, notches, and cavitation at the lowest cost.

[0034] In summary, the laser shock peening technology in this invention utilizes a high-energy pulsed laser to excite a strong shock wave, inducing severe plastic deformation of the surface layer and forming a deep residual compressive stress distribution. Simultaneously, it significantly refines grains and breaks down the strengthening phase, ultimately improving the fatigue strength, corrosion resistance, and microcrack propagation resistance of the repaired area. Compared with traditional mechanical shot peening and other strengthening methods, laser shock peening technology has a greater depth of action, stronger uniformity, and better controllability, and does not cause surface damage, making it one of the effective methods to improve blade service performance. This invention organically combines "laser-assisted cold spray repair" with "laser shock peening post-treatment," constructing an advanced repair process system integrating low heat input, high bonding strength, and strong residual compressive stress. It can achieve high-quality restoration and performance enhancement of aero-blades while avoiding the defects of traditional thermal repair, demonstrating significant scientific innovation and engineering practical value.

[0035] Example 1 The method for repairing aero-engine blades in this embodiment includes the following steps: Step 1: Weigh 500g of Ti6Al4V titanium alloy powder, wherein the Ti6Al4V titanium alloy powder is spherical in shape with a particle size of 0μm to 20μm. Figure 4 As shown.

[0036] Step 2: Dry the titanium alloy powder from Step 1 in a vacuum drying oven at 80°C and keep it at that temperature for 4 hours before removing it.

[0037] Step 3: The simplified aero-engine blade surface is polished smooth with 80-grit, 200-grit, 1000-grit, 1500-grit, and 2000-grit wet sandpaper, and then ultrasonically cleaned. After cleaning, sandblasting is performed to achieve a surface roughness of Ra 60μm to 80μm for the repaired area. The sand used for sandblasting the Ti6Al4V titanium alloy aero-engine blade surface is brown corundum with a particle size of 400 to 700μm, and the sandblasting pressure is 0.6MPa.

[0038] Step 4: The dried Ti6Al4V titanium alloy powder from Step 2 is sprayed onto the surface of the sandblasted Ti6Al4V titanium alloy aero-engine blade using a laser-assisted cold spraying method, forming a laser-assisted cold spraying deposition repair layer with a thickness of 2000μm. During the laser-assisted cold spraying process, nitrogen is used as the carrier gas, the carrier gas pressure is 1.0MPa, the spraying distance is 15mm, the spray gun speed is 50mm / s, the spraying temperature is 400℃, the laser power is 1200W, and the powder feeding speed is 0.5r / min.

[0039] Step 5, Laser Shock Pretreatment: The laser-assisted cold spray deposited repair layer is processed using wire cutting technology to restore the aero-engine blade to its original size and surface roughness. This involves polishing the surface of the supersonic laser-deposited layer with wet sandpaper of different grits, followed by polishing the coating surface with a diamond polishing agent with a grit size of 0.5 microns. Then, using ethanol as a solution, the laser-assisted cold spray deposited repair layer and the aero-engine blade are placed in an ultrasonic cleaning chamber for ultrasonic cleaning. After cleaning, the supersonic laser-deposited layer and the aero-engine blade are placed in a drying oven for drying at 80°C for 1 hour.

[0040] Step 7, Laser Shock Enhancement: Laser shock is used to enhance the supersonic laser deposition layer and the aero-engine blade; wherein the laser energy is controlled at 6J, the pulse width is 10ns, the spot diameter is 3mm, and the spot overlap rate is 50%.

[0041] Reference Figure 7 As can be seen, the coating quality after repair in this embodiment is good, with a porosity of 1.05%. The microhardness test shows that the microhardness of the coating is 485±5HV, which is greater than the microhardness of the substrate.

[0042] Step 8: Conduct friction performance testing on the repair layer. A ball-disc friction and wear testing machine is used to test the surface wear resistance of the repaired area. The grinding material is a φ6mm Si3N4 ceramic ball, the load is 10N, the sliding speed is 0.1m / s, the total stroke is 500m, and the ambient temperature is 25±2℃. Based on the experimental results, the wear rate of the repair layer is 2.1±0.3×10⁻⁶. -5 mm 3 / N·m, compared to 3.8±0.4×10⁻⁶ for the undamaged matrix. -5 mm 3 The friction coefficient was reduced by 45% / N·m; and the average friction coefficient of the repair layer in the stable stage was 0.32±0.04, with a fluctuation range smaller than that of the substrate (0.41±0.02), indicating that the anti-adhesive wear ability of the repair layer was significantly improved.

[0043] Step 9: Conduct corrosion performance tests on the repair layer. Perform a salt spray corrosion test by continuously spraying with a 5wt% NaCl aqueous solution for 96 hours to evaluate the surface corrosion morphology of the repair area. Simultaneously, perform electrochemical tests by measuring the potentiodynamic polarization curve in a 3.5wt% NaCl aqueous solution using a three-electrode system at a scan rate of 1mV / s. The reference electrode is a saturated calomel electrode.

[0044] After 96 hours of salt spray corrosion, the surface morphology of the repair layer showed no pitting or peeling, while the unreinforced repair layer showed localized pitting (density > 20 pits / cm³). 2The corrosion current density of the repair layer, Icorr, was obtained through electrochemical testing: Icorr = (0.17±0.03) μA / cm. 2 Compared to the matrix (0.52±0.06 μA / cm) 2 The voltage was reduced by 67%, and the passivation range was widened to 1.2V, indicating that laser shock peening significantly improved the stability of the passivation film.

[0045] Example 2 The method for repairing aero-engine blades in this embodiment includes the following steps: Step 1: Weigh 500g of Ti6Al4V titanium alloy powder, wherein the Ti6Al4V titanium alloy powder is spherical in shape with a particle size of 0μm to 50μm. Figure 5 As shown.

[0046] Step 2: Dry the titanium alloy powder from Step 1 in a vacuum drying oven at 80°C and keep it at that temperature for 4 hours before removing it.

[0047] Step 3: The simplified aero-engine blade surface is polished smooth with 80-grit, 200-grit, 1000-grit, 1500-grit, and 2000-grit wet sandpaper, and then ultrasonically cleaned. After cleaning, it is sandblasted to achieve a surface roughness of Ra60μm for the repaired area. The sand used for sandblasting the Ti6Al4V titanium alloy aero-engine blade surface is brown corundum with a particle size of 400-700μm, and the sandblasting pressure is 0.6MPa.

[0048] Step 4: The dried Ti6Al4V titanium alloy powder from Step 2 is sprayed onto the surface of the sandblasted Ti6Al4V titanium alloy aero-engine blade using a laser-assisted cold spraying method, forming a laser-assisted cold spraying deposition repair layer with a thickness of 2000μm. During the laser-assisted cold spraying process, nitrogen is used as the carrier gas, the carrier gas pressure is 3.0MPa, the spraying distance is 30mm, the spray gun speed is 100mm / s, the spraying temperature is 600℃, the laser power is 1600W, and the powder feeding speed is 1.2 r / min.

[0049] Step 5, Laser Shock Pretreatment: The laser-assisted cold spray deposited repair layer is processed using wire cutting technology to restore the aero-engine blade to its original size and surface roughness. This involves polishing the surface of the supersonic laser-deposited layer with wet sandpaper of different grits, followed by polishing the coating surface with a diamond polishing agent with a grit size of 0.5 microns. Then, using ethanol as a solution, the laser-assisted cold spray deposited repair layer and the aero-engine blade are placed in an ultrasonic cleaning chamber for ultrasonic cleaning. After cleaning, the supersonic laser-deposited layer and the aero-engine blade are placed in a drying oven for drying at 80°C for 1 hour.

[0050] Step 7, Laser Shock Enhancement: Laser shock is used to enhance the supersonic laser deposition layer and the aero-engine blade; wherein the laser energy is controlled at 3J, the pulse width is 10ns, the spot diameter is 6mm, and the spot overlap rate is 50%.

[0051] Reference Figure 8 As can be seen, the coating quality after repair in this embodiment is good, with a porosity of 1.05%. The microhardness test shows that the microhardness of the coating is 485±5HV, which is greater than the microhardness of the substrate.

[0052] Step 8: Conduct friction performance testing on the repair layer. A ball-disc friction and wear testing machine is used to test the surface wear resistance of the repaired area. The grinding material is a φ6mm Si3N4 ceramic ball, the load is 10N, the sliding speed is 0.1m / s, the total stroke is 500m, and the ambient temperature is 25±2℃. Based on the experimental results, the wear rate of the repair layer is 2.0±0.3×10⁻⁶. -5 mm 3 / N·m, compared to 3.8±0.4×10⁻⁶ for the undamaged matrix. -5 mm 3 The friction coefficient was reduced by 46% / N·m; and the average friction coefficient of the repair layer in the stable stage was 0.32±0.04, with a fluctuation range smaller than that of the substrate (0.41±0.02), indicating that the anti-adhesive wear ability of the repair layer was significantly improved.

[0053] Step 9: Conduct corrosion performance tests on the repair layer. Perform a salt spray corrosion test by continuously spraying with a 5wt% NaCl aqueous solution for 96 hours to evaluate the surface corrosion morphology of the repair area. Simultaneously, perform electrochemical tests by measuring the potentiodynamic polarization curve in a 3.5wt% NaCl aqueous solution using a three-electrode system at a scan rate of 1mV / s. The reference electrode is a saturated calomel electrode.

[0054] After 96 hours of salt spray corrosion, the surface morphology of the repair layer showed no pitting or peeling, while the unreinforced repair layer showed localized pitting (density > 20 pits / cm³). 2 The corrosion current density of the repair layer, Icorr, was obtained through electrochemical testing: Icorr = (0.17±0.03) μA / cm. 2 Compared to the matrix (0.52±0.06 μA / cm) 2 The voltage was reduced by 64%, and the passivation range was widened to 1.2V, indicating that laser shock peening significantly improved the stability of the passivation film.

[0055] Example 3 The method for repairing aero-engine blades in this embodiment includes the following steps: Step 1: Weigh 500g of Ti6Al4V titanium alloy powder, wherein the Ti6Al4V titanium alloy powder is spherical in shape with a particle size of 0μm to 100μm. Figure 6 As shown.

[0056] Step 2: Dry the titanium alloy powder from Step 1 in a vacuum drying oven at 80°C and keep it at that temperature for 4 hours before removing it.

[0057] Step 3: The simplified aero-engine blade surface is polished smooth with 80-grit, 200-grit, 1000-grit, 1500-grit, and 2000-grit wet sandpaper, and then ultrasonically cleaned. After cleaning, it is sandblasted to achieve a surface roughness of Ra80μm for the repaired area. The sand used for sandblasting the Ti6Al4V titanium alloy aero-engine blade surface is brown corundum with a particle size of 400-700μm, and the sandblasting pressure is 0.6MPa.

[0058] Step 4: The dried Ti6Al4V titanium alloy powder from Step 2 is sprayed onto the surface of the sandblasted Ti6Al4V titanium alloy aero-engine blade using a laser-assisted cold spraying method, forming a laser-assisted cold spraying deposition repair layer with a thickness of 2000μm. During the laser-assisted cold spraying process, nitrogen is used as the carrier gas, the carrier gas pressure is 1.0MPa, the spraying distance is 25mm, the spray gun speed is 80mm / s, the spraying temperature is 400℃, the laser power is 2000W, and the powder feeding speed is 2.0 r / min.

[0059] Step 5, Laser Shock Pretreatment: The laser-assisted cold spray deposited repair layer is processed using wire cutting technology to restore the aero-engine blade to its original size and surface roughness. This involves polishing the surface of the supersonic laser-deposited layer with wet sandpaper of different grits, followed by polishing the coating surface with a diamond polishing agent with a grit size of 0.5 microns. Then, using ethanol as a solution, the laser-assisted cold spray deposited repair layer and the aero-engine blade are placed in an ultrasonic cleaning chamber for ultrasonic cleaning. After cleaning, the supersonic laser-deposited layer and the aero-engine blade are placed in a drying oven for drying at 80°C for 1 hour.

[0060] Step 7, Laser Shock Enhancement: Laser shock is used to enhance the supersonic laser deposition layer and the aero-engine blade; wherein the laser energy is controlled at 12J, the pulse width is 30ns, the spot diameter is 6mm, and the spot overlap rate is 50%.

[0061] Reference Figure 9 and Figure 10 As can be seen, the coating quality after repair in this embodiment is good, with a porosity of 0.56%. The microhardness test shows that the microhardness of the coating is 520±5HV, which is greater than that of the substrate.

[0062] Step 8: Conduct friction performance testing on the repair layer. A ball-disc tribological tester was used to test the surface wear resistance of the repaired area. The grinding material was a φ6mm Si3N4 ceramic ball, the load was 10N, the sliding speed was 0.1m / s, the total stroke was 500m, and the ambient temperature was 25±2℃. Based on the experimental results, the wear rate of the repair layer was 1.8±0.3×10⁻⁶. -5 mm 3 / N·m, compared to 3.8±0.4×10⁻⁶ for the undamaged matrix. -5 mm 3 The friction coefficient was reduced by 48% / N·m; and the average friction coefficient of the repair layer in the stable stage was 0.32±0.04, with a fluctuation range smaller than that of the substrate (0.41±0.02), indicating that the anti-adhesive wear ability of the repair layer was significantly improved.

[0063] Step 9: Conduct corrosion performance tests on the repair layer. Perform a salt spray corrosion test by continuously spraying with a 5wt% NaCl aqueous solution for 96 hours to evaluate the surface corrosion morphology of the repair area. Simultaneously, perform electrochemical tests by measuring the potentiodynamic polarization curve in a 3.5wt% NaCl aqueous solution using a three-electrode system at a scan rate of 1mV / s. The reference electrode is a saturated calomel electrode.

[0064] After 96 hours of salt spray corrosion, the surface morphology of the repair layer showed no pitting or peeling, while the unreinforced repair layer showed localized pitting (density > 20 pits / cm³). 2 The corrosion current density of the repair layer, Icorr, was obtained through electrochemical testing: Icorr = (0.17±0.03) μA / cm. 2 Compared to the matrix (0.52±0.06 μA / cm) 2 The voltage was reduced by 69%, and the passivation range was widened to 1.2V, indicating that laser shock peening significantly improved the stability of the passivation film.

[0065] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for repairing aero-engine blades, characterized in that, The process includes the following: Powder material for repairing aero-engine blades is deposited on the part of the blade to be repaired using a laser-assisted cold spraying method, forming a laser-assisted cold spraying deposited repair layer on the surface of the part to be repaired. The laser-assisted cold spraying deposited repair layer is then processed to the original dimensional accuracy and surface roughness of the blade to be repaired. Finally, the laser-assisted cold spraying deposited repair layer is reinforced by laser shock, and the repair is completed. The powder material used to repair aero-engine blades is micron-sized titanium alloy powder.

2. The method for repairing an aero-engine blade according to claim 1, characterized in that, The micron-sized titanium alloy powder is spherical Ti6Al4V powder.

3. The method for repairing an aero-engine blade according to claim 2, characterized in that, The particle size of the micron-sized Ti6Al4V powder is less than 100 μm.

4. The method for repairing an aero-engine blade according to claim 1, characterized in that, The thickness of the laser-assisted cold spray deposition repair layer is 1900~2100μm.

5. The method for repairing an aero-engine blade according to claim 1, characterized in that, When powder material used to repair aero-engine blades is deposited onto the area to be repaired on the blade using a laser-assisted cold spraying method: The parameters for laser-assisted cold spraying include: carrier gas pressure of 1.0–3.0 MPa, spraying distance of 15–30 mm, spray gun moving speed of 50–80 mm / s, spraying temperature of 400–600℃, powder feeding speed of 0.5 r / min–2.0 r / min, and laser power of 1200 W–2000 W.

6. The method for repairing an aero-engine blade according to claim 1, characterized in that, When laser shock is used to enhance the laser-assisted cold spray deposition repair layer, the laser shock enhancement parameters include: laser energy of 3J~12J, pulse width of 10ns~30ns, spot diameter of 3mm~6mm, and spot overlap rate of 45%~55%.

7. The method for repairing an aero-engine blade according to claim 1, characterized in that, The damage types of the parts of the blade to be repaired include one or more of the following: surface fatigue cracks, cavitation pits, wear pits, corrosion pits, and edge defects.

8. The method for repairing an aero-engine blade according to claim 7, characterized in that, It also includes a pretreatment process for the parts of the blade to be repaired, including: The surface of the part to be repaired on the blade is successively sanded with water sandpaper, ultrasonically cleaned and sandblasted, and then powder material is deposited by laser-assisted cold spraying. Among them, the sandblasting treatment makes the surface roughness of the part to be repaired reach Ra60μm~80μm. During the sandblasting treatment, the sand is brown corundum with a particle size of 400μm~700μm, and the compressed air pressure during sandblasting is 0.5 MPa~0.7MPa.

9. A method for repairing an aero-engine blade according to claim 1, characterized in that, After processing the laser-assisted cold spray deposition repair layer to the original dimensional accuracy and surface roughness of the blade to be repaired, the blade to be repaired with the laser-assisted cold spray deposition repair layer is ultrasonically cleaned and dried using ethanol as a solution. After drying, the laser-assisted cold spray deposition repair layer is then enhanced by laser shock.

10. A method for repairing an aero-engine blade according to claim 1, characterized in that, The repair blade is made of a high-temperature alloy material, including titanium alloy, cobalt-based high-temperature alloy, or nickel-based high-temperature alloy.

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