Metal surface microstructure precise preparation method and device based on nanosecond laser

Abstract

The invention belongs to the technical field of metal surface laser processing, and particularly relates to a metal surface microstructure precise preparation method and device based on nanosecond laser. Carrying out scanning processing on the metal sample with the surface covered with the flowing liquid film by adopting nanosecond laser processing equipment; wherein the flowing liquid film is a carbon nano tube suspension and is used for removing deposition residues generated in the processing process. According to the method, the microstructure with the needed shape and arrangement mode can be rapidly and efficiently created on the metal surface, the problems that the microstructure on the metal surface is staggered and disordered and poor in forming after nanosecond laser machining are solved, the machining efficiency and quality of the nanosecond laser microstructure can be remarkably improved, the microstructure is improved, and the surface performance is improved. Meanwhile, the process is simple, flexibility is high, and 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 accurately preparing metal surface microstructure based on nanosecond laser. Background Art

[0002] In recent years, the field of using laser processing to manufacture microstructured surfaces on metal substrates has become a key area of ​​great concern and in-depth exploration by researchers. With the rapid development of 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 structure 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 accuracy and effect, they also have obvious disadvantages. On the one hand, the preparation process is extremely cumbersome and requires many complex processes, which requires extremely high technical level of operators. On the other hand, the cost of related equipment is high, the preparation process is relatively cumbersome, and the environmental requirements are also extremely harsh.

[0003] In recent years, nanosecond laser has attracted wide attention as an efficient laser microstructure processing method. Compared with photolithography, femtosecond and picosecond lasers, nanosecond laser is cheaper and simpler to operate. However, there are still some problems to be solved in the surface manufacturing of metal substrate microstructures using nanosecond laser. For example, its pulse duration is relatively long, and it is very easy to produce a heat-affected zone during the microstructure processing, resulting in reduced processing accuracy. The resulting microstructure is uneven, disordered and rough, and the quality is poor. At the same time, it 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 microstructure based on nanosecond laser. By removing the deposited residues generated during the processing process through the 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 purpose, the present invention provides a method for precise preparation of metal surface microstructure 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 a 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.

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

[0010] Furthermore, the scanning process is a 90° rotation and 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 nanosecond laser-based precise preparation device for metal surface microstructure, 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 flowing liquid film regulating 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;

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

[0016] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0017] 1. The nanosecond laser-based metal surface microstructure precision preparation method provided by the present invention removes the deposited residues generated during the processing by flowing liquid film, thereby dynamically optimizing the structure of the microscopic geometric morphology area, solving the problem of uneven and poorly formed metal surface microstructure after nanosecond laser processing, significantly improving the efficiency and quality of microstructure processing, and having great application prospects in the fields of mold forming, optical device manufacturing, micro-parts processing, functional surface treatment, etc. Among them, carbon nanotube nanoparticles have suitable optical properties under laser irradiation, such as the ability to absorb and scatter laser energy, which will not affect the laser scanning effect, and help 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 required 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 It is a schematic structural diagram of a nanosecond laser-based metal surface microstructure precision preparation device of the present invention;

[0021] Figure 2 A schematic diagram of the equidistant machining operation 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 purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain 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 can be combined with each other as long as they do not conflict with each other.

[0027] like Figure 1 The present invention provides a nanosecond laser-based metal surface microstructure precision preparation device, including 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 pass through the flowing liquid film to scan and process the surface of the metal sample. The flowing 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 speed of the carbon nanotube suspension in the nozzle; the nanosecond laser processing equipment includes 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 pipelines and reliable signal transmission methods, the real-time monitored liquid flow is transmitted to the speed regulator, which then accurately controls the liquid flow rate. The speed regulator is directly related to the nozzle. By controlling the liquid pressure and flow, it ensures that the nozzle can spray liquid with a suitable flow rate as required.

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

[0030] (1) Mechanically grinding and polishing the metal sample, ultrasonically cleaning and drying it in anhydrous ethanol;

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

[0032] (3) The position of the metal sample can be flexibly fixed and adjusted by an adjustable fixture, the laser irradiation parameters can be controlled, and the microstructure can be created on the surface of the metal to be processed using nanosecond laser;

[0033] (4) Regulating the flow liquid film control device to dynamically optimize the structure of the micro-geometric morphology area simultaneously, removing the irregular deposited materials and particle aggregates in the microstructure formed by laser processing at the microscale, improving the material removal rate, and obtaining 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 and deionized water are ultrasonically mixed using an ultrasonic instrument to prepare a colloidal suspension containing 0.1-5 wt % of nanoparticles, preferably 0.2-2 wt %, and more preferably 0.5 wt %.

[0042] Secondly, the compressed air is mixed with the colloidal suspension, and the flow rate of the colloidal suspension spray is controlled to 50-80mL / s using a liquid flow meter and a speed regulator. During the nanosecond laser processing process, the adjustable fixture is controlled to allow the liquid spray to continuously form an ultra-thin flowing liquid film less than 1mm 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 have suitable optical properties under laser irradiation, such as the ability to absorb and scatter laser energy. Secondly, they help to improve the material removal rate and can effectively improve the surface quality of the microstructure. Carbon nanotube nanoparticles will also help remove impurities generated by processing during the flow process without causing damage to the processed microstructure. In addition, carbon nanotube nanoparticles can maintain a good dispersion state in the colloidal suspension and prevent agglomeration to ensure uniform distribution when forming an ultra-thin flowing liquid film.

[0045] The present invention designs an equidistant machining trajectory, controls laser irradiation parameters, and uses nanosecond lasers to create microstructures of the required shape and arrangement on the metal surface to be processed. The flow film control device is adjusted to dynamically optimize the structure of the micro-geometric morphology area simultaneously, which significantly improves the efficiency and quality of microstructure processing, improves the microstructure, and enhances the surface performance.

[0046] Example 1

[0047] The present embodiment provides a nanosecond laser-based metal surface microstructure precision preparation method, and the specific implementation steps are as follows:

[0048] (1) Use silicon carbide sandpaper with mesh numbers of 400#, 800#, 1200#, 2000#, and 5000# to mechanically grind the surface of the titanium alloy sample until there are no obvious scratches, and then use nylon polishing cloth and W0.5 diamond polishing paste to polish the prepared sample to a mirror surface. The roughness of the polished sample surface is less than 20nm. Put it in anhydrous ethanol for ultrasonic cleaning and then dry it;

[0049] (2) Adjust the height of the sample stage 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;

[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 less than 1mm on the workpiece surface. The nanosecond laser is used to perform an array cross-scan on the titanium alloy surface to prepare a microstructure on the titanium alloy surface.

[0051] Figure 3 (A) and (B) are respectively the electron microscope scanning morphology pictures before and after the precise preparation of the microstructure on the titanium alloy surface by nanosecond laser. It can be seen that before the precise preparation (that is, the difference from Example 1 is that it is not covered with a flowing liquid film), there are irregular deposits and particles on the microstructure surface caused by laser processing. Due to the thermal damage of the laser, part of the deposits and particles are melted together to form large defects, the processing accuracy is low, and the formed microstructure is messy and rough. After the precise preparation, most of the deposited residues and particles on the surface of the microstructure are removed, and it is more stable and regular.

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

[0053] Example 2

[0054] The present embodiment provides a nanosecond laser-based metal surface microstructure precision preparation method, and the specific implementation steps are as follows:

[0055] (1) Use silicon carbide sandpaper with mesh numbers 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 roughness of the polished sample surface 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 processing trajectory diagram drawn by the laser processing 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 distribution. 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 processing 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 using a nanosecond laser to prepare a microstructure on the stainless steel surface.

[0058] Figure 5 (A) and (B) show the electron microscope scanning morphology pictures before and after the nanosecond laser microstructure precision preparation on the stainless steel surface. It can be seen that before the precision preparation, there are irregular deposits and particles on the microstructure surface, and some of the deposits and particles are fused together, forming a messy and rough microstructure. After the precision preparation, most of the deposits and particle aggregates on the microstructure surface are removed, making it more stable and regular.

[0059] Figure 6As shown in (A) and (B), they are the microstructure contours of the stainless steel surface after nanosecond laser microstructure precision preparation. It can be seen that after the microstructure surface is precisely prepared, the jagged and disordered microstructure is optimized, and the contour curve is smoother and regular, tending to a sine curve.

[0060] It will be easily understood by those skilled in the art that the above description is only 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 protection scope of the present invention.

Claims

1. A method for accurately preparing metal surface microstructure 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 residues generated during the processing.

2. The method for accurately preparing 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%, preferably 0.2-2%.

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

4. The method for accurately preparing metal surface microstructure 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.

5. The method for accurately preparing 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 185-195mm; the scanning power is 10-20W, the scanning speed is 100-300mm / s, the scanning interval is 0.02-0.08mm, and the pulse width is 40-55ns.

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

7. The method for accurately preparing 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.

8. The method for accurately preparing metal surface microstructure based on nanosecond laser according to claim 7, 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.

9. A nanosecond laser-based device for accurately preparing metal surface microstructures, characterized in that: It comprises 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.

10. The nanosecond laser-based metal surface microstructure precision preparation device according to claim 9, characterized in that: The flowing liquid film regulating 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 equipment comprises a nanosecond laser, an optical gate, a beam expander, a reflector and a galvanometer which are sequentially arranged on an optical path, and the laser beam is irradiated to the surface of the metal sample through the galvanometer.

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