Method for locally repairing copper-aluminum polyester abradable coating

Abstract

The invention relates to a method for locally repairing a copper-aluminum polyester abradable coating. The method comprises the following steps: performing selected area shielding on a defect area; low-pressure fine sand is adopted for sand blasting treatment; re-shielding the to-be-repaired area; the preheating temperature is increased, the spraying speed is increased, and spraying is conducted again till the repairing thickness meets the requirement; and finally cooling and cleaning the workpiece. By optimizing the process parameters such as shielding, sand blasting, preheating and spraying speed, precise minimally invasive repair of local defects of the coating is achieved, the wear resistance and adhesive force of the coating of the repaired part are effectively improved, it is ensured that the performance of the repaired area is consistent with that of an original coating, meanwhile, the repair cost and time are greatly reduced, and the repair efficiency is improved. The method is suitable for quick maintenance of abradable coatings of high-performance equipment parts such as aero-engines and gas turbines.

Description

Technical Field

[0001] This invention relates to the field of rework technology, and in particular to a method for local rework of copper-aluminum polyester wear-resistant coatings. Background Technology

[0002] Copper-aluminum-polyester abrasive coating is a functional coating prepared using copper powder, aluminum powder, and polyester resin as the core substrate, supplemented with wear-resistant fillers and additives through a specific process. It combines excellent wear resistance, sealing performance, and compatibility. Its unique abrasive properties enable precise fit and wear compensation between moving parts, effectively reducing frictional wear, preventing media corrosion, and extending equipment service life. This coating is widely used in the rotor-stator clearance sealing areas of power machinery such as aero-engines, gas turbines, and compressors, as well as in critical friction interfaces of precision machinery and fluid transport equipment.

[0003] Copper-aluminum polyester abrasive coatings are typically thick, ranging from 0.8 to 2 mm. They are prone to defects such as pinholes, cracks, insufficient adhesion, localized peeling, and scratches due to incomplete substrate pretreatment, imbalanced process parameters, uneven material dispersion, or damage during transport and assembly. These defects directly affect the initial performance of the coating and the quality of equipment assembly. Under long-term operating conditions, the coating is susceptible to localized scratches, peeling, or wear due to high-speed friction, media erosion, and assembly collisions. Existing repair technologies suffer from poor repair effects and insufficient compatibility, severely impacting equipment operational stability. Typically, the entire coating is removed for repair, but this method is time-consuming and wasteful. Therefore, how to accurately repair localized defects while ensuring coating quality, without requiring overall recoating, and while reducing material waste and manufacturing costs, has become a pressing technical challenge in the coating preparation process. Summary of the Invention

[0004] To address the problems encountered in existing production technologies, this applicant provides a method for localized repair of copper-aluminum polyester abrasive coatings. This method effectively solves the problems of high difficulty in repairing localized damage to existing coatings, weak adhesion between the repaired area and the original coating, inconsistent performance, and material waste, low construction efficiency, and high costs associated with overall recoating. By optimizing the masking method, sandblasting parameters, preheating parameters, spraying parameters, repair process parameters, and operating procedures, precise repair of the damaged area is achieved. This ensures a high degree of matching between the repair layer and the original coating in terms of composition, structure, and mechanical properties, improving the abrasion resistance, adhesion, and sealing of the repaired area, and guaranteeing the overall protective effect and service life of the coating. Simultaneously, it simplifies the repair operation, shortens the construction cycle, reduces material consumption and construction costs, and meets the practical needs of rapid, efficient, and high-quality repair of localized coating damage in industrial settings.

[0005] The technical solution adopted in this invention is as follows: A method for localized repair of copper-aluminum polyester abrasive coating includes the following steps: S1, shielding; For workpieces requiring coating repair, use sandblasting tape to cover them. The size of the sandblasting area should be larger than the size of the defect, and the distance from the edge of the defect should be controlled within 10-20mm on each side. S2, Sandblasting; Dry sandblasting is performed using 100-150 mesh white corundum abrasive particles. The sandblasting pressure is 0.10-0.3MPa, the sandblasting distance is 100-200mm, and the sandblasting coverage is greater than 100%. S3, Cleaning; Use compressed air to blow away the sandblasted surface; S4, Secondary occlusion; Use thermal spraying special tape to cover the repair area. The exposed spraying area is smaller than the sandblasting area in step S2, and the distance between the two edges is less than 5mm. S5, clamping; The workpiece processed in step S4 is installed in the rework fixture, and the surface of the workpiece is blown with compressed air. S6, Coating repair; Preheat the workpiece to a temperature 30-60°C higher than that of the new coating process. Increase the spraying speed by 30%-100% compared to the new process. The spray gun parameters are: current 350-370A, argon flow rate 140-160NLPM, hydrogen flow rate 1.5-2.5NLPM, powder feed rate 40±5g / min, and spray to the preset thickness. S7, Cooling; The workpiece processed in step S6 is air-cooled to room temperature. S8, Clean; Remove the thermal spraying tape and wipe the workpiece surface with alcohol to remove residual adhesive. S9. Done.

[0006] Its further technical solution lies in: In S1, the reserved size of the shielding area should be larger than the defect size, and the distance on one side should be controlled at 18mm.

[0007] In S2, the blasting medium is 120-mesh white corundum abrasive, the blasting pressure is 0.15MPa, and the blasting coverage is 100%-200%.

[0008] In S4, the exposed sprayed area is smaller than the sandblasted area, and the distance between the edges of the two is 3mm.

[0009] In the S6, the SinplexPro™-90 spray gun is used for spraying, and the preheating temperature is 60°C higher than that of the new process, and the spraying speed is increased by 60%.

[0010] The beneficial effects of this invention are as follows: This invention enables precise and minimally invasive repair of defective areas. By locating and defining defects based on visual inspection, combined with selective removal techniques such as micro-blasting, the surface of defective areas can be effectively cleaned without damaging the surrounding healthy coatings and substrates, fundamentally overcoming the drawbacks of traditional "small defects, large-scale treatment".

[0011] This invention significantly improves economic benefits and efficiency. Compared to the overall recoating process, this method reduces rework costs by more than 70%, shortens the rework cycle from several days to several hours, and increases material utilization by more than 60%, greatly enhancing the maintenance and support efficiency of gas turbines or aero engines.

[0012] This invention provides reliable repair quality and excellent performance. Surface pretreatment, including low-pressure fine sand treatment and high-temperature activated spraying, combined with a high-speed spraying deposition strategy, ensures a good bond between the old and new coatings, with a bonding strength no less than that of the original coating. Subsequent finishing processes guarantee that the dimensional and positional tolerances of the repaired area match the design requirements.

[0013] In summary, this invention not only provides a feasible partial rework solution, but also establishes a standardized rework process that is efficient, low-cost, and high-quality, which is of great significance for improving the efficiency and economic efficiency of thermally sprayed copper-aluminum polyester wear-resistant coatings.

[0014] This invention is applied to the preparation of wearable coatings for sealing components of aero engines, gas turbines, and automobiles, and provides a method for local rework during the preparation of copper-aluminum-polyester wearable coatings for sealing components. Attached Figure Description

[0015] Figure 1 This is a schematic diagram showing the appearance of the dents and bumps that appear after the coating is applied according to the present invention.

[0016] Figure 2 This is a schematic diagram showing the appearance of the coating after partial repair according to the present invention.

[0017] Figure 3 This is a schematic diagram of the metallographic microstructure of the coating applied in one application without any repairs according to the present invention.

[0018] Figure 4 This is a schematic diagram of the metallographic microstructure of the coating in the local repair area of ​​the present invention.

[0019] Figure 5 This is a schematic diagram of the coating appearance after partial repair and machining according to the present invention. Detailed Implementation

[0020] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0021] like Figures 1-5 As shown, the method for localized repair of the copper-aluminum polyester abrasive coating in this embodiment includes the following steps: S1, shielding; For workpieces requiring coating repair, use sandblasting tape to cover them. The size of the sandblasting area should be larger than the size of the defect, and the distance from the edge of the defect should be controlled within 10-20mm on each side. S2, Sandblasting; Dry sandblasting is performed using 100-150 mesh white corundum abrasive particles. The sandblasting pressure is 0.10-0.3MPa, the sandblasting distance is 100-200mm, and the sandblasting coverage is greater than 100%. S3, Cleaning; Use compressed air to blow away the sandblasted surface; S4, Secondary occlusion; Use thermal spraying special tape to cover the repair area. The exposed spraying area is smaller than the sandblasting area in step S2, and the distance between the two edges is less than 5mm. S5, clamping; The workpiece processed in step S4 is installed in the rework fixture, and the surface of the workpiece is blown with compressed air. S6, Coating repair; Preheat the workpiece to a temperature 30-60°C higher than that of the new coating process. Increase the spraying speed by 30%-100% compared to the new process. The spray gun parameters are: current 350-370A, argon flow rate 140-160NLPM, hydrogen flow rate 1.5-2.5NLPM, powder feed rate 40±5g / min, and spray to the preset thickness. S7, Cooling; The workpiece processed in step S6 is air-cooled to room temperature. S8, Clean; Remove the thermal spraying tape and wipe the workpiece surface with alcohol to remove residual adhesive. S9. Done.

[0022] In S1, the reserved size of the shielding area should be larger than the defect size, and the distance on one side should be controlled at 18mm.

[0023] In S2, the blasting medium is 120-mesh white corundum abrasive, the blasting pressure is 0.15MPa, and the blasting coverage is 100%-200%.

[0024] In S4, the exposed sprayed area is smaller than the sandblasted area, and the distance between the edges of the two is 3mm.

[0025] In the S6, the SinplexPro™-90 spray gun is used for spraying, and the preheating temperature is 60°C higher than that of the new process, and the spraying speed is increased by 60%.

[0026] Newly applied copper-aluminum polyester abrasive coatings are prone to surface impacts, resulting in insufficient coating thickness. Alternatively, excessive coating thickness can lead to internal cracking. This embodiment provides a localized repair method for situations where only the copper-aluminum polyester abrasive coating has been damaged without reaching the underlying layer.

[0027] Example 1: The specific implementation method of the new system is as follows: Masking: Completely mask the non-coating areas of the workpiece, exposing only the pre-designed coating preparation area; during the masking process, ensure that the tape is applied smoothly, the edges are sealed, and there are no wrinkles or gaps to prevent sand particles from entering the non-coating areas and causing damage during subsequent sandblasting.

[0028] Sandblasting: Dry sandblasting is performed on the workpiece. The sandblasting medium is 24-mesh white corundum abrasive particles, the sandblasting pressure is 0.3MPa, the sandblasting distance is 100-200mm, and the sandblasting coverage is greater than 200%.

[0029] Cleaning: Use compressed air to blow away the sandblasted surface to clean it and prevent the presence of contaminants.

[0030] Secondary masking: Use thermal spraying special tape to mask the non-spraying areas, leaving only the spraying areas exposed.

[0031] Clamping: Install the masked workpiece onto the thermal spraying fixture and clean it with compressed air to avoid contamination during the clamping process.

[0032] Base coat application: Using a SinplexPro™-90 spray gun, Ni5Al powder is sprayed as the base coat, with a coating thickness of 0.12mm. Current 400±10A, argon flow rate 50NLPM, hydrogen flow rate 3NLPM, powder feed rate 30±5g / min, spraying speed 600m / min, preheating temperature 120℃.

[0033] Copper-aluminum polyester abrasive coating was prepared by spraying Cu 8.5Al 1Fe10 polyester powder using a SinplexPro™-90 spray gun. The coating thickness was greater than 1.2 mm. The operating parameters were: current 360±10A, argon flow rate 150 NLPM, hydrogen flow rate 2 NLPM, powder feed rate 40±5 g / min, spraying speed 600 m / min, and preheating temperature 120℃.

[0034] Cooling: Air cool to room temperature.

[0035] Cleaning: Manually remove the thermal spraying tape, wipe with alcohol to remove residual adhesive, and clean the workpiece.

[0036] After preparation, it was found to be 10cm 2 Copper-aluminum polyester abrasion-resistant coating impact damage, such as Figure 1 As shown.

[0037] Example 2: The specific implementation method for partial rework is as follows: S1, shielding; For workpieces requiring coating repair, use sandblasting-specific tape to cover them. The size of the exposed sandblasting area should be larger than the defect size, and the distance from the defect edge should be controlled within 18mm on each side. S2, Sandblasting; For coatings with localized defects, dry sandblasting is performed using 120-mesh white corundum abrasive particles, a sandblasting pressure of 0.15 MPa, a sandblasting distance of 180-200 mm, and a sandblasting coverage of 100%-200% (ensuring that no areas of the substrate surface are missed). S3, Cleaning; Use compressed air to blow away the sandblasted surface and clean it thoroughly to remove any contaminants. S4, Secondary occlusion; Use thermal spraying special tape to cover the rework area. The exposed spraying area is smaller than the sandblasting area in step S2, and the distance between the two edges is 2-3mm on each side, so as to minimize the area affected by the rework. S5, clamping; The workpiece processed in step S4 is installed in the rework fixture, and the surface of the workpiece is blown with compressed air to avoid contamination during the clamping process. S6, Coating repair; A copper-aluminum polyester abrasive coating was prepared by spraying Cu 8.5Al 1Fe10 polyester powder using a SinplexPro™-90 spray gun. The preheating temperature was 180℃, the current was 360A, the argon flow rate was 150NLPM, the hydrogen flow rate was 2NLPM, the powder feed rate was 40g / min, the spraying speed was 1000m / min, and the coating thickness was greater than 0.8mm. S7, Cooling; The workpiece processed in step S6 is air-cooled to room temperature. S8, Clean; Remove the thermal spraying tape and wipe the workpiece surface with alcohol to remove residual adhesive. S9. Done.

[0038] The reworked coating covered the original defects, meeting the part's requirements for the thickness of the copper-aluminum polyester wear-resistant coating. See details. Figure 1 and Figure 2 .

[0039] The metallographic structure of the repaired coating is good, and there is no obvious interface with the original healthy coating. See details. Figure 3 and Figure 4 .

[0040] The coating cross-section after partial repair showed good adhesion, comparable to that of a one-time sprayed coating, as detailed in Table 1: Table 1. Test results of bond strength before and after localized repair coating.

[0041] The repaired coating was machined by turning. Subsequent finishing of the repaired area resulted in a good surface finish, ensuring that the dimensional and positional tolerances matched the design requirements. See details. Figure 5 .

[0042] This invention achieves precise repair and minimizes damage: By limiting the sandblasting area and the masking range, minimally invasive treatment of defective areas can be achieved, avoiding secondary damage to healthy coatings and substrates, and overcoming the problem of "small defects, big treatment" caused by traditional overall recoating.

[0043] This invention provides high-quality repair and strong bonding. By employing low-pressure fine sandblasting and high-temperature preheating spraying processes, the bonding strength between the new and old coatings is significantly improved. The bonding strength in the repair area is comparable to that of the original coating, ensuring the consistency of the overall coating performance.

[0044] This invention boasts high process efficiency and significantly reduced costs: Compared to the overall recoating process, this method shortens the repair cycle from several days to several hours, increases material utilization by more than 60%, and reduces repair costs by more than 70%, making it suitable for rapid repair needs in industrial settings.

[0045] This invention has a wide range of applications and standardized operation: This method is applicable to the local repair of coatings on high-value components such as aero engines and gas turbines. It has clear process parameters, strong operability, and is easy to standardize, thereby improving production economy and maintenance support efficiency.

[0046] This invention offers controllable geometric tolerances and superior post-processing performance. After repair, the coating was machined to a good surface condition, and the dimensional and positional tolerances met the design requirements, without affecting the assembly and performance of the parts.

[0047] The above description is an explanation of the present invention and not a limitation thereof. The scope of the present invention is defined by the claims. Within the scope of protection of the present invention, any form of modification may be made.

Claims

1. A method for local repair of a copper-aluminum-polyester abradable coating, characterized in that: The following steps are included: S1, shielding; For workpieces requiring coating repair, use sandblasting tape to cover them. The size of the sandblasting area should be larger than the size of the defect, and the distance from the edge of the defect should be controlled within 10-20mm on each side. S2, Sandblasting; Dry sandblasting is performed using 100-150 mesh white corundum abrasive particles. The sandblasting pressure is 0.10-0.3MPa, the sandblasting distance is 100-200mm, and the sandblasting coverage is greater than 100%. S3, Cleaning; Use compressed air to blow away the sandblasted surface; S4, Secondary occlusion; Use thermal spraying special tape to cover the repair area. The exposed spraying area is smaller than the sandblasting area in step S2, and the distance between the two edges is less than 5mm. S5, clamping; The workpiece processed in step S4 is installed on the rework fixture, and the surface of the workpiece is blown with compressed air. S6, Coating repair; Preheat the workpiece to a temperature 30-60°C higher than that of the new coating process. Increase the spraying speed by 30%-100% compared to the new process. The spray gun parameters are: current 350-370A, argon flow rate 140-160NLPM, hydrogen flow rate 1.5-2.5NLPM, powder feed rate 40±5g / min, and spray to the preset thickness. S7, Cooling; The workpiece processed in step S6 is air-cooled to room temperature. S8, Clean; Remove the thermal spraying tape and wipe the workpiece surface with alcohol to remove residual adhesive. S9. Done.

2. A method for local repair of a copper-aluminum-polyester abradable coating according to claim 1, characterized in that In S1, the reserved size of the shielding area should be larger than the defect size, and the distance on one side should be controlled at 18mm.

3. A method for local repair of a copper-aluminum-polyester abradable coating according to claim 1, characterized in that: In S2, the blasting medium is 120-mesh white corundum abrasive, the blasting pressure is 0.15MPa, and the blasting coverage is 100%-200%.

4. A method for local repair of a copper-aluminum-polyester abradable coating according to claim 1, characterized in that: In S4, the exposed sprayed area is smaller than the sandblasted area, and the distance between the edges of the two is 3mm.

5. A method for locally repairing a copper-aluminum-polyester abradable coating according to claim 1, characterized in that: In the S6, the SinplexPro™-90 spray gun is used for spraying, and the preheating temperature is 60°C higher than that of the new process, and the spraying speed is increased by 60%.

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