Method for fabricating multi-scale desorption microstructures on the surface of engine exhaust nozzle workpieces using femtosecond lasers

Abstract

The present invention discloses a method for fabricating multi-scale desorption microstructures on the surface of an engine exhaust nozzle workpiece using a femtosecond laser, comprising: Step 1, homogenizing the focused spot of the femtosecond laser using an acousto-optic modulation device; Step 2, focusing the laser focus onto the surface of the engine exhaust nozzle workpiece to be processed; Step 3, performing layer-by-layer scanning processing using a scanning galvanometer to form V-groove microstructures at a scale of tens of micrometers; Step 4, processing overlapping V-groove microstructures; Step 5, repeating Step 4 multiple times until all V-groove microstructures are processed on the surface of the engine exhaust nozzle workpiece to be processed, forming an array of V-groove structures; Step 6, resetting the femtosecond laser parameters; and Step 7, performing multiple scans along the bottom of the V-groove microstructures using a scanning galvanometer to form multi-scale microstructures within the V-groove microstructures. The method of the present invention can effectively solve the problem of carbon buildup in aero-engine exhaust nozzles, and has the advantages of being environmentally friendly and highly efficient.

Description

Technical Field

[0001] This invention relates to a laser processing method, specifically a method for processing multi-scale desorption microstructures on the surface of an engine exhaust nozzle workpiece using a femtosecond laser. Background Technology

[0002] As a key component of the aircraft engine's exhaust system, the tail nozzle's primary function is to allow the exhaust gases after the turbine to continue expanding and be ejected at high speed from the nozzle, generating reaction thrust. This is crucial for achieving high agility and short takeoff and landing capabilities. During engine operation, a large amount of exhaust gas is produced, which can adhere to the surface of the tail nozzle, causing the stealth coating to fail, reducing the engine's stealth performance, and making it highly detectable by radar.

[0003] The deposits in the tailpipes of aircraft engines are mainly carbon deposits and other environmental deposits produced by the incomplete combustion of fuel and lubricating oil. The main components are hydroxy acids, asphaltenes, tar, etc. Traditionally, carbon deposits can only be cleaned with chemical solvents during major overhauls. The cleaning cycle is long and causes environmental pollution, which directly affects the return to service life of aircraft engines.

[0004] Preparing multi-scale desorption microstructures on the surface of the tail nozzle can quickly remove carbon deposits with clean water after prolonged use of aero engines. This is an effective way to solve the problem of carbon buildup in aero engine tail nozzles, with the advantages of no environmental pollution and high efficiency. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problem of difficult carbon deposit treatment in aero-engine exhaust nozzles, and to provide a method for processing multi-scale desorption microstructures on the surface of engine exhaust nozzle workpieces using femtosecond lasers. This method can effectively solve the problem of carbon deposits in aero-engine exhaust nozzles and has the advantages of no environmental pollution and high efficiency.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for fabricating multi-scale desorption microstructures on the surface of an engine exhaust nozzle workpiece using femtosecond lasers is characterized by the following steps:

[0008] Step 1: Set two acousto-optic modulation devices in sequence on the optical path between the femtosecond laser and the scanning galvanometer in the femtosecond laser processing device. Place the engine tail nozzle workpiece to be processed on the outgoing optical path after the scanning galvanometer and the field mirror of the femtosecond laser processing device. Use the acousto-optic modulation devices to homogenize the focused spot of the femtosecond laser.

[0009] Step 2: Set the power, scanning speed, number of scanning layers and scanning path of the femtosecond laser, and focus the laser emitted after passing through the scanning galvanometer and field mirror onto the surface of the engine tail nozzle workpiece to be processed.

[0010] Step 3: Use a scanning galvanometer to perform layered scanning processing to form a V-groove microstructure on the scale of tens of micrometers;

[0011] Step 4: Move the scanning beam of the scanning galvanometer laterally by the width of a V-groove microstructure, and repeat step 3 to fabricate overlapping V-groove microstructures.

[0012] Step 5: Repeat step 4 multiple times until all V-groove microstructures are machined on the surface of the engine tail nozzle workpiece to be processed, forming an array of V-groove structures.

[0013] Step 6, reset the power of the femtosecond laser. 、 The scanning speed, number of scanning layers, and scanning path affect the power of the femtosecond laser. 、 The scanning speed and number of scanning layers are higher than the corresponding parameters in step 2. The laser focus emitted after passing through the scanning galvanometer and field mirror is focused to a position 0.9-1.1 mm above the surface of the engine tail nozzle workpiece to be processed, and corresponds to a V-groove microstructure in the array V-groove structure.

[0014] Step 7: Use a scanning galvanometer to scan the bottom of the V-groove microstructure multiple times to form a multi-scale microstructure in the V-groove microstructure.

[0015] Step 8: Laterally move the scanning beam of the scanning galvanometer by the width of a V-groove microstructure, and repeat step 7 to form a multi-scale microstructure in another overlapping V-groove microstructure.

[0016] Step 9: Repeat step 8 multiple times until multi-scale microstructures are machined on the surface of the engine exhaust nozzle workpiece, thus completing the machining of multi-scale desorption microstructures on the surface of the engine exhaust nozzle.

[0017] Furthermore, in step 1, the specific method for homogenization is as follows:

[0018] Step 1.1: Turn on the two sound and light modulation devices and adjust their adjustment angles to be perpendicular to each other;

[0019] Step 1.2: Adjust the parameters of the acousto-optic modulator to focus the laser of the femtosecond laser, and then superimpose the focused spot to obtain a homogenized spot with a larger size than the focused spot.

[0020] Furthermore, step 7 specifically involves:

[0021] Step 7.1: Scan the bottom of one of the V-groove microstructures in the fabricated array V-groove structure;

[0022] Step 7.2: Perform five consecutive scans to fabricate a multi-scale microstructure with a scale of 800 nanometers on the bottom surface of the array V-groove microstructure.

[0023] Furthermore, in step 2, the power of the femtosecond laser is 2-3W; the scanning speed is 150mm / s-200mm / s; and the number of scanning layers is 2-3 layers.

[0024] 5. The method for processing multi-scale desorption microstructures on the workpiece surface of an engine exhaust nozzle using femtosecond laser according to claim 4, characterized in that: in step 3, the depth and width of the V-groove microstructure are both 80 micrometers.

[0025] Furthermore, in step 5, the power of the femtosecond laser is 13-18W; the scanning speed is 330mm / s-550mm / s; and the number of scanning layers is 4-5.

[0026] Furthermore, in step 1, the emitted beam of the femtosecond laser is 10 mm, and the focal length of the field lens is less than 50 mm.

[0027] Furthermore, in step 6, the laser emitted after passing through the scanning galvanometer and field mirror is focused to a point 1 mm above the surface of the engine tail nozzle workpiece to be processed.

[0028] Furthermore, the feature is that: in step 1, the homogenization degree of the light spot intensity of the homogenization treatment is ≥85%.

[0029] Furthermore, step 9 specifically includes:

[0030] Step 9.1, repeat step 8 multiple times until multi-scale microstructures are machined on the entire surface of the engine tail nozzle workpiece to be processed.

[0031] Step 9.2: Immerse the engine tail nozzle workpiece in a 99% concentration fluorosilane solution for 2 hours.

[0032] Step 9.3: Remove the engine exhaust nozzle workpiece from the fluorosilane solution and place it in a drying oven. Dry it at 60 degrees Celsius for 2 hours to complete the processing on the surface of the engine exhaust nozzle and obtain a multi-scale desorption microstructure.

[0033] Compared with the prior art, the present invention has the following beneficial technical effects:

[0034] This invention discloses a method for fabricating multi-scale desorption microstructures on the surface of engine exhaust nozzles using femtosecond lasers. After homogenization of the focused spot of the femtosecond laser, an array of V-grooves is fabricated on the surface of the workpiece. A scanning galvanometer is then used to scan the bottom of the array of V-grooves multiple times to form a multi-scale structure. This multi-scale desorption microstructure, applied to the surface of exhaust nozzles, can rapidly remove carbon deposits from aero-engines after prolonged use using clean water, solving the problem of carbon buildup in aero-engine exhaust nozzles. It offers advantages such as no environmental pollution and high efficiency, and has broad application prospects. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of a femtosecond laser processing apparatus according to an embodiment of the present invention;

[0036] Figure 2 This is an image showing the effect of homogenizing the laser focusing spot after homogenization processing in step 1 of this embodiment of the invention.

[0037] Figure 3 This is a schematic diagram of the V-groove microstructure processed using an embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of the array V-groove structure processed using an embodiment of the present invention;

[0039] Figure 5 This is a schematic diagram of the multi-scale desorption microstructure processed using the embodiments of the present invention, wherein (a) is a schematic diagram of the surface structure of the multi-scale desorption microstructure, and (b) is a partially enlarged view of the surface structure of the multi-scale desorption microstructure. Detailed Implementation

[0040] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0041] The present invention provides a method for processing multi-scale desorption microstructures on the surface of an engine exhaust nozzle workpiece using a femtosecond laser. The processing system implementing this method has the following characteristics:

[0042] The two sets of acousto-optic modulation devices (AOD) are orthogonally placed, and their scanning directions are consistent with the two scanning directions of the galvanometer. The focal length of the field lens is selected to be related to the diameter of the emitted beam of the femtosecond laser, ensuring that the diameter of the focused spot behind the field lens is less than 10 micrometers.

[0043] like Figures 1-5 As shown, a specific embodiment of the method for processing multi-scale desorption microstructures using femtosecond lasers according to the present invention includes the following steps:

[0044] Step 1: Configure the processing system: the femtosecond laser output beam is 10 mm, and the field lens focal length is less than 50 mm.

[0045] Step 2: Turn on the two acousto-optic modulation devices to rapidly scan the femtosecond laser beam along two axes. Adjust the acousto-optic modulator parameters to cause the focused beams to overlap. After beam overlap, a larger square homogenized beam will be obtained, such as... Figure 2 As shown, the size should be less than 30 micrometers, and the homogenization degree of the light spot intensity should be ≥85%.

[0046] Step 3: Set the femtosecond laser power to low power, and simultaneously set the galvanometer scanning speed, number of scanning layers, and scanning path to precisely focus the laser on the surface of the workpiece to be processed. The parameters here are greatly related to the structure processed. The galvanometer scanning speed is 150mm / s, the number of scanning layers is 3, and the femtosecond laser power is 2W.

[0047] Step 4: Using a galvanometer, layer-by-layer scanning is performed to form a V-groove microstructure with a depth and width of 80 micrometers. The V-groove is fabricated by removing layers progressively, with each layer removing a smaller area than the last, until a V-groove is formed. Figure 3 As shown. The laser parameters remain unchanged for each layer of processing. When processing a layer, the Z-axis is fed downwards by a certain distance (that is, the focal point moves downwards, and the distance depends on the processing depth of a single layer).

[0048] Step 5: Repeat step 4 to fabricate an array of overlapping V-grooves. Here, adjusting the galvanometer simply moves the scanning beam laterally by the width of one V-groove, achieving overlap between the ridges of the V-grooves. Figure 4 As shown.

[0049] Step 6: Reset the femtosecond laser to high power, and simultaneously set the galvanometer scanning speed and number of scanning layers. Focus the laser on a point 1 mm above the surface of the workpiece to be processed (this value can be between 0.9 mm and 1.1 mm depending on different requirements); focus error ±0.1 mm; these parameters are highly dependent on the structure being processed. The processing parameters are: scanning speed 330 mm / s, 5 scans; femtosecond laser power 13 W; higher power, faster speed, and more scans compared to step 2.

[0050] Step 7: Defocus the laser on the processing surface and set the galvanometer scanning path, scanning only the bottom of the V-groove already processed in step 5. By performing 5 scans along the bottom of the array V-groove structure using the galvanometer, an 800-nanometer-scale microstructure will be processed on the surface of the array V-groove structure, forming a multi-scale structure. The processed structure is shown below. Figure 5 As shown, (a) indicates that the surface of the V-groove is macroscopically V-shaped. When magnified further, as shown in (b), the surface of the V-groove is entirely composed of nanoparticles.

[0051] Step 8: Place the processed workpiece into a 99% concentration fluorosilane solution and soak for 2 hours;

[0052] Step 9: Remove the workpiece from the solution and place it in a drying oven. Dry it at 60 degrees Celsius for 2 hours.

[0053] A second embodiment of the method for processing multi-scale desorption microstructures on the surface of an engine exhaust nozzle workpiece using a femtosecond laser according to the present invention includes the following steps:

[0054] Step 1: Configure the processing system: the femtosecond laser output beam is 10 mm, and the field lens focal length is less than 50 mm.

[0055] Step 2: Turn on the two acousto-optic modulation devices to rapidly scan the femtosecond laser beam along two axes. Adjust the acousto-optic modulator parameters to cause the focused beams to overlap. After beam overlap, a larger square homogenized beam will be obtained, such as... Figure 2 As shown, the size should be less than 30 micrometers, and the homogenization degree of the light spot intensity should be ≥85%.

[0056] Step 3: Set the femtosecond laser power to low power, and simultaneously set the galvanometer scanning speed and the number of scanning layers to precisely focus the laser on the surface of the workpiece to be processed. The parameters here are greatly related to the structure processed. The galvanometer scanning speed is 200mm / s, the number of scanning layers is 2, and the femtosecond laser power is 3W.

[0057] Step 4: Using a galvanometer, layer-by-layer scanning is performed to form a V-groove microstructure with a depth and width of 80 micrometers. The V-groove is fabricated by removing layers progressively, with each layer removing a smaller area than the last, until a V-groove is formed. Figure 3 As shown. The laser parameters remain unchanged for each layer of processing. When processing a layer, the Z-axis is fed downwards by a certain distance (that is, the focal point moves downwards, and the distance depends on the processing depth of a single layer).

[0058] Step 5: Repeat step 4 to fabricate an array of overlapping V-grooves. Here, adjusting the galvanometer simply moves the scanning beam laterally by the width of one V-groove, achieving overlap between the ridges of the V-grooves. Figure 4 As shown.

[0059] Step 6: Reset the femtosecond laser to high power, and simultaneously set the galvanometer scanning speed and the number of scanning layers. Focus the laser at a point 1 mm above the surface of the workpiece to be processed (this value can be between 0.9 mm and 1.1 mm depending on different requirements), with a focusing error of ±0.1 mm. Generally, these parameters are closely related to the structure being processed. The galvanometer scanning speed is 550 mm / s, the number of scanning layers is 4, and the femtosecond laser power is 18 W, which is higher in power, faster in speed, and has more scans than in Step 2.

[0060] Step 7: Defocus the laser on the processing surface and set the galvanometer scanning path, scanning only the bottom of the V-grooves already processed in step 5. Using the galvanometer, perform 5 scans along the bottom of the array of V-grooves to process 800-nanometer-scale microstructures on the surface of the array of V-grooves, forming a multi-scale structure. The processed structure is shown below. Figure 5 As shown, (a) indicates that the surface of the V-groove is macroscopically V-shaped. When magnified further, as shown in (b), the surface of the V-groove is entirely composed of nanoparticles.

[0061] 8. Place the processed workpiece into a 99% concentration fluorosilane solution and soak for 3 hours;

[0062] 9. Remove the workpiece from the solution and place it in a drying oven. Dry it at 60 degrees Celsius for 3-4 hours.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A method for fabricating multi-scale desorption microstructures on the surface of an engine exhaust nozzle workpiece using a femtosecond laser, characterized in that, Includes the following steps: Step 1: Set two acousto-optic modulation devices in sequence on the optical path between the femtosecond laser and the scanning galvanometer in the femtosecond laser processing device. Place the engine tail nozzle workpiece to be processed on the outgoing optical path after the scanning galvanometer and the field mirror of the femtosecond laser processing device. Use the acousto-optic modulation devices to homogenize the focused spot of the femtosecond laser. Step 2: Set the power, scanning speed, number of scanning layers and scanning path of the femtosecond laser, and focus the laser emitted after passing through the scanning galvanometer and field mirror onto the surface of the engine tail nozzle workpiece to be processed. Step 3: Use a scanning galvanometer to perform layered scanning processing to form a V-groove microstructure on the scale of tens of micrometers; Step 4: Move the scanning beam of the scanning galvanometer laterally by the width of a V-groove microstructure, and repeat step 3 to fabricate overlapping V-groove microstructures. Step 5: Repeat step 4 multiple times until all V-groove microstructures are machined on the surface of the engine tail nozzle workpiece to be processed, forming an array of V-groove structures. Step 6, reset the power of the femtosecond laser. 、 The scanning speed, number of scanning layers, and scanning path affect the power of the femtosecond laser. 、 The scanning speed and number of scanning layers are higher than the corresponding parameters in step 2. The laser focus emitted after passing through the scanning galvanometer and field mirror is focused to a position 0.9-1.1 mm above the surface of the engine tail nozzle workpiece to be processed, and corresponds to a V-groove microstructure in the array V-groove structure. Step 7: Use a scanning galvanometer to scan the bottom of the V-groove microstructure multiple times to form a multi-scale microstructure in the V-groove microstructure. Step 8: Laterally move the scanning beam of the scanning galvanometer by the width of a V-groove microstructure, and repeat step 7 to form a multi-scale microstructure in another overlapping V-groove microstructure. Step 9: Repeat step 8 multiple times until multi-scale microstructures are machined on the surface of the engine exhaust nozzle workpiece, thus completing the machining of multi-scale desorption microstructures on the surface of the engine exhaust nozzle.

2. The method for processing multi-scale desorption microstructures on the surface of an engine exhaust nozzle workpiece using a femtosecond laser according to claim 1, characterized in that, In step 1, the specific method for homogenization is as follows: Step 1.1: Turn on the two sound and light modulation devices and adjust their adjustment angles to be perpendicular to each other; Step 1.2: Adjust the parameters of the acousto-optic modulator to focus the laser of the femtosecond laser, and then superimpose the focused spot to obtain a homogenized spot with a larger size than the focused spot.

3. The method for processing multi-scale desorption microstructures on the surface of an engine exhaust nozzle workpiece using a femtosecond laser according to claim 2, characterized in that, Step 7 specifically involves: Step 7.1: Scan the bottom of one of the V-groove microstructures in the fabricated array V-groove structure; Step 7.2: Perform five consecutive scans to fabricate a multi-scale microstructure with a scale of 800 nanometers on the bottom surface of the array V-groove microstructure.

4. The method for processing multi-scale desorption microstructures on the surface of an engine exhaust nozzle workpiece using a femtosecond laser according to claim 3, characterized in that: In step 2, the power of the femtosecond laser is 2-3W; the scanning speed is 150mm / s-200mm / s; and the number of scanning layers is 2-3.

5. The method for processing multi-scale desorption microstructures on the surface of an engine exhaust nozzle using a femtosecond laser according to claim 4, characterized in that: In step 3, the depth and width of the V-groove microstructure are both 80 micrometers.

6. The method for processing multi-scale desorption microstructures on the surface of an engine exhaust nozzle workpiece using a femtosecond laser according to claim 5, characterized in that: In step 5, the power of the femtosecond laser is 13-18W; the scanning speed is 330mm / s-550mm / s; and the number of scanning layers is 4-5.

7. The method for processing multi-scale desorption microstructures on the surface of an engine exhaust nozzle workpiece using a femtosecond laser according to claim 6, characterized in that: In step 1, the emitted beam of the femtosecond laser is 10 mm, and the focal length of the field lens is less than 50 mm.

8. The method for processing multi-scale desorption microstructures on the surface of an engine exhaust nozzle workpiece using a femtosecond laser according to claim 1, characterized in that: In step 6, the laser emitted after passing through the scanning galvanometer and field mirror is focused to a point 1 mm above the surface of the engine tail nozzle workpiece to be processed.

9. The method for processing multi-scale desorption microstructures on the surface of an engine exhaust nozzle workpiece using a femtosecond laser according to claim 2, characterized in that: In step 1, the homogenization degree of the light spot intensity is ≥85%.

10. The method for processing multi-scale desorption microstructures on the surface of an engine exhaust nozzle workpiece using a femtosecond laser according to any one of claims 1-9, characterized in that, Step 9 specifically includes: Step 9.1, repeat step 8 multiple times until multi-scale microstructures are machined on the entire surface of the engine tail nozzle workpiece to be processed. Step 9.2: Immerse the engine tail nozzle workpiece in a 99% concentration fluorosilane solution for 2 hours. Step 9.3: Remove the engine exhaust nozzle workpiece from the fluorosilane solution and place it in a drying oven. Dry it at 60 degrees Celsius for 2 hours to complete the processing on the surface of the engine exhaust nozzle and obtain a multi-scale desorption microstructure.

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