A nanosecond laser-based method and device for precise preparation of metal surface microstructures

Abstract

The present invention belongs to the technical field of metal surface laser processing, and specifically relates to a method and device for the precise preparation of metal surface microstructures based on nanosecond lasers. Nanosecond laser processing equipment is used to scan and process a metal sample whose surface is covered with a flowing liquid film; wherein the flowing liquid film is a carbon nanotube suspension, which is used to remove the deposited residues generated during the processing. The present invention can quickly and efficiently create a microstructure of the required shape and arrangement on the metal surface, solving the problem of uneven and poorly formed metal surface microstructures after nanosecond laser processing, and can significantly improve the efficiency and quality of nanosecond laser microstructure processing, improve the microstructure, and enhance surface performance. At the same time, the process is simple, flexible, and the operation is simple and efficient.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal surface laser processing, and specifically relates to a method and device for precisely preparing metal surface microstructures based on nanosecond laser. Background Art

[0002] The use of laser processing to create microstructured surfaces on metal substrates has become a key area of ​​research attention and in-depth exploration in recent years. In today's rapidly changing science and technology, people have an increasingly strong demand for shaping fine and functional microstructured surfaces on metal substrates. However, at this stage, when preparing metal structured surfaces, most cases use extremely expensive photolithography technology, as well as advanced methods such as femtosecond lasers and picosecond lasers. Although these methods have certain advantages in precision and effect, they also have obvious disadvantages. On the one hand, the preparation process is extremely cumbersome and requires multiple complex steps, which requires a very high level of technical skills from the operator. On the other hand, the cost of the relevant equipment is high, the preparation process is relatively cumbersome, and the environmental requirements are also extremely harsh.

[0003] In recent years, nanosecond lasers have attracted widespread attention as a highly efficient laser microstructuring method. Compared with photolithography, femtosecond, and picosecond lasers, nanosecond lasers are cheaper and simpler to operate. However, there are still some problems to be solved in the use of nanosecond lasers in the surface fabrication of microstructures on metal substrates. For example, the pulse duration is relatively long, and heat-affected zones are easily generated during the microstructuring process, resulting in reduced processing accuracy. The resulting microstructures are uneven, disordered, rough, and of poor quality. At the same time, they may also cause thermal damage to the material, which can easily damage the material's microstructure and make it difficult to meet the requirements of large-scale production. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and device for the precise preparation of metal surface microstructures based on nanosecond lasers. By removing the deposited residues generated during the processing process through a flowing liquid film, the structure of the micro-geometric morphology area can be dynamically optimized, thereby significantly improving the efficiency and quality of microstructure processing, improving the microstructure, and enhancing the surface performance.

[0005] To achieve the above-mentioned objectives, the present invention provides a method for precise preparation of metal surface microstructures based on nanosecond laser, comprising: using nanosecond laser processing equipment to perform laser scanning processing on a metal sample whose surface is covered with a flowing liquid film; wherein the flowing liquid film is a carbon nanotube suspension, which is used to remove the deposited residue generated during the processing.

[0006] Furthermore, the solvent of the carbon nanotube suspension is deionized water, and the mass content of the carbon nanotubes is 0.1-5%, preferably 0.2-2%.

[0007] Furthermore, the thickness of the flowing liquid film is less than 1 mm.

[0008] Furthermore, the flowing liquid film is formed by spraying a carbon nanotube suspension from a nozzle disposed at the metal sample, and the spraying speed of the carbon nanotube suspension is 50-80 mL / s.

[0009] Furthermore, the focusing distance of the scanning processing of the nanosecond laser processing equipment is 185-195 mm; the scanning power is 10-20 W, the scanning speed is 100-300 mm / s, the scanning interval is 0.02-0.08 mm, and the pulse width is 40-55 ns.

[0010] Furthermore, the scanning process is a 90° rotation ten times array cross scanning.

[0011] Furthermore, the surface roughness of the metal sample is less than 20 nm.

[0012] Furthermore, the metal sample is mechanically ground and polished before use; the material of the metal sample is titanium alloy or stainless steel.

[0013] The present invention also provides a device for precise preparation of metal surface microstructure based on nanosecond laser, comprising nanosecond laser processing equipment, a sample stage and a flowing liquid film control device; the sample stage is used to fix the metal sample; the flowing liquid film control device is used to control the flow state of the carbon nanotube suspension to form a flowing liquid film on the surface of the metal sample; the nanosecond laser processing equipment is used to emit nanosecond laser and scan the metal sample surface through the flowing liquid film.

[0014] Furthermore, the flow liquid film control device includes a speed regulator, a liquid flow meter and a nozzle connected in sequence, and a glass cover arranged above the sample stage; the speed regulator and the liquid flow meter are used to control the flow rate of the carbon nanotube suspension in the nozzle;

[0015] The nanosecond laser processing equipment includes a nanosecond laser, a shutter, a beam expander, a reflector and a galvanometer mirror which are sequentially arranged on an optical path. The laser beam is irradiated to the surface of the metal sample through the galvanometer mirror.

[0016] In general, the above technical solutions conceived by the present invention have the following technical advantages compared with the existing technology:

[0017] 1. The nanosecond laser-based precision metal surface microstructure preparation method provided by the present invention removes the deposited residue generated during the processing by flowing a liquid film, thereby dynamically optimizing the structure of the microscopic geometric morphology area. This solves the problems of uneven and poorly formed metal surface microstructures after nanosecond laser processing, significantly improves the efficiency and quality of microstructure processing, and has great application prospects in mold forming, optical device manufacturing, micro-parts processing, functional surface treatment and other fields. Among them, carbon nanotube nanoparticles have suitable optical properties under laser irradiation, such as the ability to absorb and scatter laser energy, which does not affect the laser scanning effect, helps to improve the material removal rate, and can effectively improve the surface quality of the microstructure.

[0018] 2. The present invention designs an equidistant processing trajectory, controls laser irradiation parameters, and uses nanosecond laser to quickly and efficiently create a microstructure of the desired shape and arrangement on the surface of the metal to be processed.

[0019] 3. The present invention has great application prospects in the fields of mold forming, optical device manufacturing, micro-parts processing, functional surface treatment, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of the device for accurately preparing metal surface microstructure based on nanosecond laser of the present invention;

[0021] Figure 2 Schematic diagram of the isometric machining trajectory designed for the present invention;

[0022] Figure 3 This is a scanning electron microscope image of the titanium alloy surface microstructure before and after nanosecond laser dynamic optimization in Example 1 of the present invention;

[0023] Figure 4 This is a contour diagram of the titanium alloy surface microstructure before and after nanosecond laser dynamic optimization in Example 1 of the present invention;

[0024] Figure 5 This is a scanning electron microscope image of the stainless steel surface microstructure before and after nanosecond laser dynamic optimization in Example 2 of the present invention;

[0025] Figure 6 This is a contour diagram of the stainless steel surface microstructure before and after nanosecond laser dynamic optimization in Example 2 of the present invention. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0027] like Figure 1 The present invention provides a device for the precise preparation of metal surface microstructures based on nanosecond lasers, comprising a nanosecond laser processing device, a sample stage, and a flow liquid film control device; the sample stage is used to fix the metal sample; the flow liquid film control device is used to control the flow state of the carbon nanotube suspension to form a flow liquid film on the surface of the metal sample; the nanosecond laser processing device is used to emit nanosecond laser and scan the metal sample surface through the flow liquid film. The flow liquid film control device comprises a speed regulator, a liquid flow meter, and a nozzle connected in sequence, and a glass cover arranged above the sample stage; the speed regulator and the liquid flow meter are used to control the flow speed of the carbon nanotube suspension in the nozzle; the nanosecond laser processing device comprises a nanosecond laser, a light gate, a beam expander, a reflector, and a galvanometer arranged in sequence on the optical path, and the laser beam is irradiated to the surface of the metal sample through the galvanometer.

[0028] The liquid flow meter is closely connected to the speed regulator. Through high-precision piping and reliable signal transmission, it transmits real-time liquid flow to the speed regulator, which then precisely controls the liquid flow rate. The speed regulator is directly connected to the nozzle, controlling the liquid pressure and flow rate to ensure that the nozzle can spray the liquid at the required flow rate.

[0029] Specifically, the present invention provides a method for precisely preparing metal surface microstructures based on nanosecond laser, which specifically includes the following steps:

[0030] (1) The metal sample is mechanically ground and polished, and then ultrasonically cleaned and dried in anhydrous ethanol;

[0031] (2) Designing an equidistant machining trajectory and adjusting the sample stage height in the nanosecond laser processing equipment to the optimal working focusing distance;

[0032] (3) Using an adjustable fixture to flexibly fix and adjust the position of the metal sample, control the laser irradiation parameters, and use nanosecond laser to create microstructures on the surface of the metal to be processed;

[0033] (4) Adjust the flow liquid film control device to dynamically optimize the structure of the micro-geometric morphology area simultaneously, remove the irregular sedimentary materials and particle aggregates in the microstructure formed by laser processing at the micro scale, improve the material removal rate, and obtain a more stable and regular microstructure.

[0034] Furthermore, the mechanical grinding process in step (1) is: mechanically grinding the surface of the metal sample with silicon carbide sandpaper until there are no obvious scratches, and the mesh size of the silicon carbide sandpaper used is 400#, 800#, 1200#, 2000#, and 5000#, respectively.

[0035] Furthermore, the metal in step (1) is titanium alloy or stainless steel.

[0036] Furthermore, the polishing process in step (1) is: polishing the prepared sample to a mirror surface using a nylon polishing cloth and W0.5 diamond polishing paste, and the surface roughness of the polished sample is less than 20 nm.

[0037] Furthermore, the equidistant processing trajectory in step (2) is drawn using the laser processing software Ezcad, and the nanosecond laser scanning strategy is a 90° rotation ten times array cross scanning.

[0038] Furthermore, the optimal working focusing distance of the sample stage height in the nanosecond laser processing equipment in step (2) is 185-195 mm (i.e., the distance between the galvanometer and the metal sample).

[0039] Furthermore, the nanosecond laser irradiation parameter range in step (3) is: setting the laser wavelength to 1064nm, the scanning power to 10-20W, the scanning speed to 100-300mm / s, the scanning interval to 0.02-0.08mm, the pulse width to 40-55ns, and the laser energy distribution to Gaussian distribution.

[0040] Furthermore, the step (4) of synchronously performing dynamic structural optimization on the micro-geometric morphology region includes:

[0041] First, the carbon nanotubes are ultrasonically mixed with deionized water using an ultrasonic instrument to prepare a colloidal suspension containing 0.1-5 wt % of nanoparticles, preferably 0.2-2 wt %, more preferably 0.5 wt %.

[0042] Next, compressed air is mixed with the colloidal suspension, and the colloidal suspension spray flow rate is controlled at 50-80 mL / s using a liquid flow meter and speed regulator. During the nanosecond laser processing, a controllable fixture is controlled to ensure that the liquid spray continuously forms an ultra-thin flowing liquid film less than 1 mm thick on the workpiece surface.

[0043] Finally, the sample surface was ultrasonically cleaned with acetone and alcohol and then dried with nitrogen.

[0044] Carbon nanotube nanoparticles possess suitable optical properties under laser irradiation, such as the ability to absorb and scatter laser energy. Furthermore, they help increase material removal rates and effectively improve the surface quality of microstructures. During the flow process, carbon nanotube nanoparticles also assist in removing impurities generated by machining without damaging the processed microstructures. Furthermore, carbon nanotube nanoparticles maintain a well-dispersed state in colloidal suspensions, preventing agglomeration and ensuring uniform distribution when forming ultra-thin flowing liquid films.

[0045] This invention utilizes nanosecond lasers to create microstructures of the desired shape and arrangement on the metal surface being processed by designing an equidistant machining trajectory and controlling laser irradiation parameters. Adjusting the flow of the liquid film control device allows for simultaneous dynamic structural optimization of the microscopic geometrical regions, significantly improving the efficiency and quality of microstructural processing, enhancing microstructure, and improving surface properties.

[0046] Example 1

[0047] The present embodiment provides a method for precisely preparing metal surface microstructures based on nanosecond lasers, and the specific implementation steps are as follows:

[0048] (1) The titanium alloy sample surface was mechanically ground using silicon carbide sandpaper with mesh sizes of 400#, 800#, 1200#, 2000#, and 5000# until no obvious scratches were found. The prepared sample was then polished to a mirror finish using a nylon polishing cloth and W0.5 diamond polishing paste. The surface roughness of the polished sample was less than 20 nm. The sample was ultrasonically cleaned in anhydrous ethanol and then dried.

[0049] (2) Adjust the sample stage height in the nanosecond laser processing equipment so that the optimal working focusing distance of the working platform height in the nanosecond laser processing equipment is 185-195 mm;

[0050] (3) Figure 2 The figure shows the equidistant processing trajectory diagram drawn by the laser processing software Ezcad. The laser wavelength is set to 1064nm, the scanning power is 16W, the scanning speed is 300mm / s, the scanning interval is 0.06mm, the pulse width is 50ns, and the laser energy distribution is Gaussian distribution. Compressed air is mixed with a colloidal suspension containing 0.5wt% carbon nanotubes, and the flow rate of the colloidal suspension spray is controlled to 80mL / s using a liquid flow meter and a speed regulator. During the nanosecond laser processing process, the adjustable fixture is controlled so that the liquid spray continuously forms an ultra-thin flowing liquid film of less than 1mm on the workpiece surface. The nanosecond laser is used to perform array cross-scanning on the titanium alloy surface to prepare a microstructure on the titanium alloy surface.

[0051] Figure 3 Figures (A) and (B) show scanning electron microscope images of the titanium alloy surface before and after nanosecond laser microstructuring. This shows that before precision fabrication (i.e., the difference from Example 1 is that it is not covered with a flowing liquid film), the microstructure surface contains irregular microscopic deposits and particles formed by laser processing. Due to thermal damage from the laser, some of the deposits and particles fuse together, forming large defects. This results in low processing precision and a cluttered and rough microstructure. After precision fabrication, most of the deposited residues and particles on the microstructure surface are removed, resulting in a more stable and regular surface.

[0052] Figure 4 (A) and (B) show the microstructure contours of the titanium alloy surface before and after nanosecond laser microstructure precision preparation. It can be seen that after precise preparation of the microstructure surface, the jagged and disordered microstructure is optimized, and the contour curve becomes smoother and more regular.

[0053] Example 2

[0054] The present embodiment provides a method for precisely preparing metal surface microstructures based on nanosecond lasers, and the specific implementation steps are as follows:

[0055] (1) Use silicon carbide sandpaper with mesh sizes of 400#, 800#, 1200#, 2000#, and 5000# to mechanically grind the surface of the stainless steel sample until there are no obvious scratches. Then use nylon polishing cloth and W0.5 diamond polishing paste to polish the prepared sample to a mirror surface. The surface roughness of the polished sample is less than 20nm. Place it in anhydrous ethanol for ultrasonic cleaning and then dry it.

[0056] (2) Adjusting the height of the working platform in the nanosecond laser processing equipment so that the optimal working focusing distance of the working platform in the nanosecond laser processing equipment is 185-195 mm;

[0057] (3) Figure 2 The figure shows the equidistant machining trajectory diagram drawn by the laser machining software Ezcad. The laser wavelength is set to 1064nm, the scanning power is 20W, the scanning speed is 150mm / s, the scanning interval is 0.06mm, the pulse width is 45ns, and the laser energy distribution is Gaussian. Compressed air is mixed with a colloidal suspension containing nanoparticles, and the flow rate of the colloidal suspension spray is controlled to 50mL / s using a liquid flow meter and a speed regulator. During the nanosecond laser machining process, the adjustable fixture is controlled so that the liquid spray continuously forms an ultra-thin flowing liquid film less than 1mm on the workpiece surface. The stainless steel surface is scanned in an array cross-type manner using a nanosecond laser to prepare a microstructure on the stainless steel surface.

[0058] Figure 5 (A) and (B) show scanning electron microscope images of the stainless steel surface before and after nanosecond laser microstructuring. This shows that before microstructuring, the surface contained irregular deposits and particles at the microscopic scale. Some of the deposits and particles were fused together, resulting in a disordered and rough microstructure. After microstructuring, most of the deposits and particle aggregates were removed, resulting in a more stable and regular microstructure.

[0059] Figure 6(A) and (B) show the microstructure contours of the stainless steel surface after nanosecond laser microstructuring. It can be seen that after precise preparation, the jagged and disordered microstructure of the microstructure surface has been optimized, and the contour curve has become smoother and more regular, tending to a sine curve.

[0060] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for accurately preparing metal surface microstructures based on nanosecond laser, characterized in that: include: Nanosecond laser processing equipment is used to perform laser scanning processing on a metal sample whose surface is covered with a flowing liquid film; wherein the flowing liquid film is a carbon nanotube suspension, which is used to remove the deposited residue generated during the processing.

2. The method for precise preparation of metal surface microstructure based on nanosecond laser according to claim 1, characterized in that: The solvent of the carbon nanotube suspension is deionized water, and the mass content of the carbon nanotubes is 0.1-5%.

3. The method for precise preparation of metal surface microstructure based on nanosecond laser according to claim 2, characterized in that: The mass content of the carbon nanotubes is 0.2-2%.

4. The method for precisely preparing metal surface microstructures based on nanosecond laser according to claim 1, characterized in that: The thickness of the flowing liquid film is less than 1 mm.

5. The method for precisely preparing metal surface microstructures based on nanosecond laser according to claim 1, characterized in that: The flowing liquid film is formed by the carbon nanotube suspension sprayed from a nozzle disposed at the metal sample, and the spraying speed of the carbon nanotube suspension is 50-80 mL / s.

6. The method for precise preparation of metal surface microstructure based on nanosecond laser according to claim 1, characterized in that: The scanning processing focus distance of the nanosecond laser processing equipment is 185-195 mm; the scanning power is 10-20 W, the scanning speed is 100-300 mm / s, the scanning interval is 0.02-0.08 mm, and the pulse width is 40-55 ns.

7. The method for precisely preparing metal surface microstructures based on nanosecond laser according to claim 1, characterized in that: The scanning process is a 90° rotation and ten times array cross scanning.

8. The method for precise preparation of metal surface microstructure based on nanosecond laser according to claim 1, characterized in that: The surface roughness of the metal sample is less than 20 nm.

9. The method for precise preparation of metal surface microstructure based on nanosecond laser according to claim 8, characterized in that: The metal sample is mechanically ground and polished before use; the material of the metal sample is titanium alloy or stainless steel.

10. A nanosecond laser-based device for accurately preparing metal surface microstructures, characterized in that: It includes nanosecond laser processing equipment, a sample stage and a flowing liquid film control device; the sample stage is used to fix the metal sample; the flowing liquid film control device is used to control the flow state of the carbon nanotube suspension to form a flowing liquid film on the surface of the metal sample; the nanosecond laser processing equipment is used to emit nanosecond laser and scan the surface of the metal sample through the flowing liquid film.

11. The nanosecond laser-based metal surface microstructure precision preparation device according to claim 10, characterized in that: The flow liquid film control device includes a speed regulator, a liquid flow meter and a nozzle connected in sequence, and a glass cover arranged above the sample stage; the speed regulator and the liquid flow meter are used to control the flow rate of the carbon nanotube suspension in the nozzle; The nanosecond laser processing equipment includes a nanosecond laser, a shutter, a beam expander, a reflector and a galvanometer mirror which are sequentially arranged on an optical path. The laser beam is irradiated to the surface of the metal sample through the galvanometer mirror.

Images