A method for processing C / SiC composite materials based on ultrasonic vibration-assisted femtosecond laser

Abstract

A method for processing C / SiC composite materials based on ultrasound-assisted high-repetition-rate femtosecond laser, firstly building a femtosecond laser processing optical path system, the optical path comprising a high-repetition-rate femtosecond laser, the output laser of the high-repetition-rate femtosecond laser sequentially passing through a 1 / 2 wave plate, a beam splitter, a beam expander, etc., entering a galvanometer and vertically irradiating on a processing station of an ultrasonic vibration device, the amplitude of the ultrasonic vibration device being controlled by an ultrasonic generator, the position of the ultrasonic vibration device being controlled by a three-dimensional mobile platform, and controlling the galvanometer by a computer to control the power, motion trajectory speed and defocusing amount of the laser focus and the material surface during the processing of the high-repetition-rate femtosecond laser, the galvanometer and the three-dimensional mobile platform; the ultrasonic vibration cavitation effect and near-field convection enhancement effect of the invention are conducive to reducing particle shielding, better cooling of ablated particles and debris, reducing their tendency to combine with the material surface, reducing surface oxidation, and improving the processing surface quality and removal depth; the surface of the obtained C / SiC composite material is smooth and flat.

Description

Technical Field

[0001] The invention belongs to the technical field of ultrafast laser micromachining, and in particular relates to a method for processing C / SiC composite materials based on ultrasonic vibration-assisted high-repetition-rate femtosecond laser. Background Art

[0002] C / SiC composites have unique properties such as low density, high temperature resistance, high strength and toughness, and high thermal conductivity, making them attractive high-temperature structural ceramic materials for advanced aerospace propulsion engines and high-speed civil transportation applications. However, since C / SiC composites composed of carbon fiber and silicon carbide matrix are difficult to process, the reinforcing phase of carbon fiber brings anisotropy and heterogeneity, and the hardness of silicon carbide matrix is ​​second only to diamond; therefore, processing high-quality C / SiC composites is still a problem to be solved.

[0003] Mechanical processing methods for C / SiC composite materials, such as grinding and milling, are traditional and commonly used processing methods, but this method is prone to surface defects such as chipping, tearing, burrs, cracks, and fibers. These processing defects seriously affect the quality of parts and subsequent functional performance. Compared with traditional processing methods, ultrashort pulse laser processing has the characteristics of small thermal damage, high processing accuracy, low material requirements, and a wide processing range, and can achieve high-precision processing. At present, the laser processing methods used for precision processing of composite materials mainly include laser tilting processing and ultrasonic vibration-assisted laser processing. Laser tilting processing technology For the current application of laser tilting processing technology, the method of tilting the workpiece is mainly used to achieve laser tilting processing. The tilting device platform used in this method is complex, and the coordinated control operation between the various motion axes is required. The device is complex and the operation is difficult, and it is difficult to ensure the uniformity of the processing surface in the horizontal and vertical directions. Ultrasonic vibration-assisted laser processing is used to realize the processing of composite material surfaces, but the existing processing trajectory of this method mainly requires the coordinated control of the scanning galvanometer and the mobile platform. It also has the problems of complex operation and high motion accuracy requirements. Its processing efficiency is low, and the experimental effect is difficult to guarantee. In addition, most existing ultrafast laser processing technologies perform processing at the focus. Due to the high energy intensity of the laser focus, it is very easy to induce the filamentation effect, causing instability in beam transmission. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a method for processing C / SiC composite materials based on ultrasound-assisted high-repetition-rate femtosecond laser, which combines the laser and ultrasonic processing methods, and based on the cavitation effect and convection enhancement effect of ultrasonic vibration, reduces the ion shielding effect and particle deposition in the laser processing process, and improves the processing surface quality; in addition, the height of the three-dimensional mobile platform is adjusted to control the defocusing amount between the sample surface and the laser focus on the ultrasonic vibration device, thereby controlling the spot diameter and energy density, and at the same time, the scanning speed of the processing trajectory is controlled by using a scanning galvanometer. The two work together to adjust the matching relationship between the ultrasonic amplitude and the energy density, and the spot size and scanning speed are adjusted as needed to optimize the spot overlap rate to improve the processing efficiency. The method is simple to operate, has high processing efficiency, and can obtain a smooth surface without fiber breakage, fiber pullout, and holes.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for processing C / SiC composite materials based on ultrasound-assisted high-repetition-rate femtosecond laser, comprising the following steps:

[0007] 1) The C / SiC composite material is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water respectively, and then blown dry with dry nitrogen to obtain a clean C / SiC composite material sample 10;

[0008] 2) Building a femtosecond laser processing optical path system, the optical path includes a high repetition rate femtosecond laser 1, the laser output from the high repetition rate femtosecond laser 1 passes through a 1 / 2 wave plate 2, a beam splitter 4, and a first reflector 5 in sequence, the first reflector 5 rotates the optical path by 90°, and then the laser beam passes through a beam expander 6 and a second reflector 12, and then enters a galvanometer 11 through the second reflector 12 to vertically irradiate the processing station of an ultrasonic vibration device 9, wherein the amplitude of the ultrasonic vibration device 9 is controlled by an ultrasonic generator 7, and the position of the ultrasonic vibration device 9 is controlled by a three-dimensional mobile platform 8, the laser power is detected by a combination of a 1 / 2 wave plate 2, a beam splitter 4, and a power meter 3, and a computer 13 is used to control the galvanometer 11 and then control the power, movement speed, and trajectory of the high repetition rate femtosecond laser 1, the galvanometer 11, and the three-dimensional mobile platform 8 during the processing process;

[0009] 3) Fix the C / SiC composite material sample 10 to the ultrasonic vibration device 9, control the X-axis and Y-axis of the three-dimensional mobile platform 8 to provide the starting position of the sample processing area, and adjust the Z-axis to control the distance between the laser focus and the surface of the C / SiC composite material sample 10;

[0010] 4) Using the ultrasonic generator 7 to adjust the power of the ultrasonic vibration and control the amplitude of the ultrasonic vibration device 9 in the vertical direction;

[0011] 5) Using the computer 13 to adjust the output power of the high repetition rate femtosecond laser 1, wherein the laser wavelength is 1030nm, the pulse width is 240fs, and the repetition rate is 50kHz;

[0012] 6) The motion trajectory and scanning speed on the surface of the C / SiC composite material sample 10 are regulated by using the galvanometer 11, firstly performing a transverse scan and then a longitudinal scan, so as to obtain a C / SiC composite material surface with a smooth surface and no fiber damage.

[0013] In the step 3), the distance between the laser focus and the surface of the C / SiC composite material sample 10 is 0 to -5 mm, and the negative sign indicates that the laser focus is below the surface of the C / SiC composite material sample 10.

[0014] In the step 4), the vibration amplitude of the ultrasonic vibration device 9 is in the range of 10-40 μm.

[0015] In the step 5), the output power of the high repetition rate femtosecond laser 1 ranges from 2 to 12W.

[0016] In the step 6), the scanning track interval is 5 μm and the scanning speed is 200-1400 mm / s.

[0017] The beneficial effects of the present invention are:

[0018] By adjusting the ultrasonic power to control the amplitude of vibration, under the cavitation effect of ultrasonic vibration and the enhanced near-field convection, it is beneficial to reduce plasma shielding, fiber breakage, fiber pullout, holes, and surface particle deposition; by adjusting the movement of the Z axis of the three-dimensional mobile platform 8, the size of the negative defocus can be controlled, which can avoid the filament effect of the focus on the material surface under high power, and at the same time, the size of the spot diameter can be controlled, thereby controlling the size of the laser energy density and the spot overlap rate, and the matching relationship between the energy density and the ultrasonic amplitude can be adjusted to ensure the uniformity of the processing quality; by adjusting the scanning speed of the laser motion trajectory and the size of the defocus amount by the galvanometer 5, the spot overlap rate can be optimized, and the processing efficiency and quality are further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the optical path of the present invention.

[0020] Figure 2 This is a diagram of the motion trajectory of the light beam in processing C / SiC composite materials in the present invention.

[0021] Figure 3 1 is a rendering of the unprocessed C / SiC composite material in Example 1, (a) and (b) are the surface morphologies of the transverse fibers and longitudinal fibers of the femtosecond laser processed C / SiC composite material sample in Example 1 without applying ultrasonic vibration.

[0022] Figure 4 The effect diagram of laser processing of C / SiC composite material in Example 1 is shown in FIG. (a) and (b) are the surface morphologies of the transverse fibers and longitudinal fibers of the C / SiC composite material sample processed by femtosecond laser without applying ultrasonic vibration in this example.

[0023] Figure 5 This is a rendering of the effect of ultrasonic-assisted laser processing of C / SiC composite material in Example 1, (a) and (b) are the surface morphologies of the transverse fibers and longitudinal fibers of the processed sample of ultrasonic vibration-assisted femtosecond laser processing of C / SiC composite material in this example, respectively. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0025] Embodiment 1, a method for processing C / SiC composite materials based on ultrasound-assisted high repetition rate femtosecond laser, comprising the following steps:

[0026] 1) A 30×30 mm C / SiC composite material was ultrasonically cleaned with acetone, anhydrous ethanol and deionized water respectively, and then dried with dry nitrogen to obtain a clean C / SiC composite material sample 10;

[0027] 2) Build a femtosecond laser processing optical system, refer to Figure 1 , the optical path includes a high repetition rate femtosecond laser 1, the laser output from the high repetition rate femtosecond laser 1 passes through a 1 / 2 wave plate 2, a beam splitter prism 4, and a first reflector 5 in sequence, the first reflector 5 rotates the optical path by 90°, and then the laser beam passes through a beam expander 6 and a second reflector 12, and then enters a galvanometer 11 through the second reflector 12 to vertically irradiate the processing station of an ultrasonic vibration device 9, wherein the amplitude of the ultrasonic vibration device 9 is controlled by an ultrasonic generator 7, the position of the ultrasonic vibration device 9 is controlled by a three-dimensional mobile platform 8, the laser power is detected by a combination of a 1 / 2 wave plate 2, a beam splitter prism 4, and a power meter 3, and at the same time, a computer 13 is used to control the galvanometer 11 and further control the power, movement speed, and trajectory of the high repetition rate femtosecond laser 1, the galvanometer 11, and the three-dimensional mobile platform 8 during the processing process;

[0028] 3) Fix the C / SiC composite material sample 10 to the ultrasonic vibration device 9, and provide the starting position of the sample processing area by controlling the X-axis and Y-axis of the three-dimensional mobile platform 8. Adjust the Z-axis to control the distance between the laser focus and the surface of the C / SiC composite material sample 10. The distance between the laser focus and the surface of the C / SiC composite material sample 10 is -4 mm, and the negative sign indicates that the laser focus is below the surface of the C / SiC composite material sample 10;

[0029] 4) Using the ultrasonic generator 7 to adjust the power of the ultrasonic vibration, the amplitude of the ultrasonic vibration device 9 in the vertical direction is controlled so that the ultrasonic amplitude range is 28 μm;

[0030] 5) Using the computer 13 to adjust the output power of the high repetition rate femtosecond laser 1, wherein the laser wavelength is 1030nm, the pulse width is 240fs, the repetition rate is 50kHz, and the output power is 12W;

[0031] 6) Using the galvanometer 11 to control the motion trajectory and scanning speed on the surface of the C / SiC composite material sample 10, the scanning trajectory interval is set to 5 μm, the scanning speed is set to 1000 mm / s, and the horizontal scanning is first performed, and then the vertical scanning is performed. Figure 2 , that is, a C / SiC composite material surface with a smooth surface and no fiber damage is obtained, and its surface roughness reaches 1μm.

[0032] Effects of this embodiment: Figure 3 , Figure 4 , Figure 5 , Figure 3 (a) and (b) are the surface morphologies of the transverse fibers and longitudinal fibers of the C / SiC composite material sample processed by femtosecond laser without applying ultrasonic vibration in this embodiment. The surface of the material is rough, with obvious fiber breakage and pulling out, and uneven distribution; Figure 4 (a) and (b) are the surface morphologies of the transverse fibers and longitudinal fibers of the C / SiC composite material sample processed by femtosecond laser without applying ultrasonic vibration in this embodiment. The surface of the material is rough, with obvious defects such as fiber pull-out, fiber breakage and holes, and there are a large number of particle depositions and holes on the surface; Figure 5 (a) and (b) are the surface morphologies of the transverse fibers and longitudinal fibers of the C / SiC composite material processed by ultrasonic vibration-assisted femtosecond laser in this embodiment, respectively. The surface quality of the material is significantly improved, the surface of the material is smooth, and there are no defects such as fiber pullout, holes, and particle deposition.

[0033] In Example 2, the distance between the laser focus and the surface of the C / SiC composite material sample 10 in step 3) of Example 1 is changed to 0 mm; in step 4), the range of the vibration amplitude of the ultrasonic vibration device 9 is changed to 10 μm; in step 5), the output power of the high repetition rate femtosecond laser 1 is changed to 2 W; in step 6), the scanning speed is changed to 200 mm / s; the other steps are the same as in Example 1; the effect of this embodiment is similar to that of Example 1.

[0034] In Example 3, the distance between the laser focus and the surface of the C / SiC composite material sample 10 in step 3) of Example 1 is changed to -5 mm; the range of the vibration amplitude of the ultrasonic vibration device 9 in step 4) is changed to 40 μm; the scanning speed in step 6) is changed to 1400 mm / s; the other steps are the same as in Example 1; the effect of this embodiment is similar to that of Example 1.

Claims

1. A method for processing C / SiC composite materials based on ultrasound-assisted high-repetition-rate femtosecond laser, characterized in that: The following steps are involved: 1) ultrasonically cleaning the C / SiC composite material with acetone, anhydrous ethanol and deionized water respectively, and then drying with dry nitrogen to obtain a clean C / SiC composite material sample (10); 2) constructing a femtosecond laser processing optical path system, wherein the optical path includes a high repetition rate femtosecond laser (1), wherein the laser output from the high repetition rate femtosecond laser (1) passes through a 1 / 2 wave plate (2), a beam splitter (4), and a first reflector (5) in sequence, wherein the first reflector (5) rotates the optical path by 90°, and then the laser beam passes through a beam expander (6) and a second reflector (12), and then enters a galvanometer (11) via the second reflector (12) to vertically irradiate a processing station of an ultrasonic vibration device (9), wherein the amplitude of the ultrasonic vibration device (9) is controlled by an ultrasonic generator (7), and the position of the ultrasonic vibration device (9) is controlled by a three-dimensional mobile platform (8), and the laser power is detected by a combination of a 1 / 2 wave plate (2), a beam splitter (4), and a power meter (3), and at the same time, a computer (13) is used to control the galvanometer (11) and thereby control the power, movement speed, and trajectory of the high repetition rate femtosecond laser (1), the galvanometer (11), and the three-dimensional mobile platform (8) during the processing process; 3) fixing the C / SiC composite material sample (10) onto the ultrasonic vibration device (9), providing the starting position of the sample processing area by controlling the X-axis and Y-axis of the three-dimensional moving platform (8), and adjusting the Z-axis to control the distance between the laser focus and the surface of the C / SiC composite material sample (10); 4) using an ultrasonic generator (7) to control the amplitude of the ultrasonic vibration device (9) in the vertical direction; 5) using a computer (13) to adjust the output power of the high repetition rate femtosecond laser (1), wherein the laser wavelength is 1030 nm, the pulse width is 240 fs, and the repetition rate is 50 kHz; 6) Using a galvanometer (11) to control the motion trajectory and scanning speed on the surface of the C / SiC composite material sample (10), first performing a transverse scan and then a longitudinal scan, thereby obtaining a C / SiC composite material surface with a smooth surface and no fiber damage.

2. The method according to claim 1, characterized in that: In the step 3), the distance between the laser focus and the surface of the C / SiC composite material sample (10) is 0 to -6 cm, and the negative sign indicates that the laser focus is below the surface of the C / SiC composite material sample (10).

3. The method according to claim 1, characterized in that: The vibration amplitude of the ultrasonic vibration device (9) in step 4) is in the range of 10-40 μm.

4. The method according to claim 1, characterized in that: In the step 5), the output power of the high repetition rate femtosecond laser (1) ranges from 2 to 12W.

5. The method according to claim 1, characterized in that: In the step 6), the scanning track interval is 5 μm and the scanning speed is 200-1600 mm / s.

6. The method according to claim 1, characterized in that The following steps are involved: 1) ultrasonically cleaning a 30×30 mm C / SiC composite material with acetone, anhydrous ethanol and deionized water respectively, and then drying it with dry nitrogen to obtain a clean C / SiC composite material sample (10); 2) constructing a femtosecond laser processing optical path system, wherein the optical path includes a high repetition rate femtosecond laser (1), wherein the laser output from the high repetition rate femtosecond laser (1) passes through a 1 / 2 wave plate (2), a beam splitter (4), and a first reflector (5) in sequence, wherein the first reflector (5) rotates the optical path by 90°, and then the laser beam passes through a beam expander (6) and a second reflector (12), and then enters a galvanometer (11) via the second reflector (12) to vertically irradiate a processing station of an ultrasonic vibration device (9), wherein the amplitude of the ultrasonic vibration device (9) is controlled by an ultrasonic generator (7), and the position of the ultrasonic vibration device (9) is controlled by a three-dimensional mobile platform (8), and the laser power is detected by a combination of a 1 / 2 wave plate (2), a beam splitter (4), and a power meter (3), and at the same time, a computer (13) is used to control the galvanometer (11) and thereby control the power, movement speed, and trajectory of the high repetition rate femtosecond laser (1), the galvanometer (11), and the three-dimensional mobile platform (8) during the processing process; 3) fixing the C / SiC composite material sample (10) onto the ultrasonic vibration device (9), and providing the starting position of the sample processing area by controlling the X-axis, Y-axis and Z-axis of the three-dimensional moving platform (8), and the coordinated movement of the X-axis, Y-axis and Z-axis can adjust the distance between the laser focus and the surface of the C / SiC composite material sample (10), wherein the distance between the laser focus and the surface of the C / SiC composite material sample (10) is -4 cm, and the negative sign indicates that the laser focus is below the surface of the C / SiC composite material sample (10); 4) using an ultrasonic generator (7) to control the amplitude of the ultrasonic vibration device (9) in the vertical direction so that the ultrasonic amplitude is 28 μm; 5) using a computer (13) to adjust the output power of the high repetition rate femtosecond laser (1), wherein the laser wavelength is 1030 nm, the pulse width is 240 fs, the repetition rate is 50 kHz, and the output power is 12 W; 6) Using a galvanometer (11) to regulate the motion trajectory and scanning speed on the surface of the C / SiC composite material sample (10), wherein the scanning trajectory interval is set to 5 μm, the scanning speed is set to 1000 mm / s, and first a transverse scan is performed, and then a longitudinal scan is performed, so as to obtain a C / SiC composite material surface with a smooth surface and no fiber damage.

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