Method for preparing functionalized self-array micro / nano-porous surface by femtosecond laser direct writing

Abstract

The application belongs to the technical field of ultrafast laser processing, and particularly relates to a method for preparing a functionalized self-array micro / nano-porous surface by femtosecond laser direct writing. The method uses femtosecond laser direct writing technology to prepare a functionalized self-array micro / nano-porous surface on a metal glass, tungsten, chromium or other superhard alloy or metal surface without changing the characteristic properties of the raw material. The holes of the self-array micro / nano-porous surface are approximately circular, the diameter of the holes is greater than the wavelength of the used laser, and the diameter is adjustable in the range of 500 nm to 6 microns, the interval is adjustable in the range of 1 to 5 microns, and the holes present good periodicity and regularity. The self-array micro / nano-porous surface prepared by the method has the performances of infrared anti-reflection, self-cooling and heat dissipation, hydrophobicity, oleophobicity and the like, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of ultrafast laser processing technology, specifically relating to a method for rapidly preparing functionalized self-arrayed micro / nanopore surfaces on the surfaces of difficult-to-machine metals or alloys. Background Technology

[0002] The booming and diversified development of ultrafast laser micro / nanofabrication technology relies on the mutually coupled multiphysics fields and cross-dimensional effects established during the interaction between laser and matter. In the interaction between laser (especially ultrafast lasers with nonlinear effects) and matter, multiphysics coupling uniquely enables "top-down" laser fabrication with "bottom-up" self-organizing characteristics. Typical examples include laser-induced periodic surface structures, such as Laser-Induced Periodic Surface Structures (LIPSS) and Ultrawavelength Periodic Surface Structures (SWPSS), which are environmentally friendly, low-cost, efficient, and easily fabricated over large areas across dimensions.

[0003] However, self-organization effects are generally detrimental to defect suppression and high controllability in LIPSS or SWPSS, especially in scenarios significantly related to thermal / fluid dynamics processes, such as phase transitions / separation and convection. To achieve high quality and uniformity of laser-induced micro / nanostructures in these specific scenarios, a commonly used principle is to construct a pair of positive / negative feedback loops. This allows for precise manipulation of micro / nanostructures by directly utilizing the different interactions (two mutually inhibiting effects) between the laser and matter. This has been applied to "subwavelength" schemes (e.g., LIPSS) with resolutions ranging from tens to hundreds of nanometers. However, it is noteworthy that near-field enhancement or focused adjustment of far-field laser beams is frequently used as so-called positive feedback in subwavelength laser fabrication to selectively enhance laser-induced multi-physics coupling transduction and changes in the state of matter, essentially "clamping" the fabrication in space. Near-field coupling of far-field light into optical micro / nanostructures can improve the focusing resolution and accuracy of optical imaging and optical fabrication, or enable larger-scale optical manipulation of micro / nanostructures. However, research on controllable fabrication techniques for “ultrawavelength” micro / nanostructured functional surfaces with feature sizes larger than the wavelength of the laser used (such as SWPSS) is still very limited. These techniques are more related to complex thermodynamics / fluid dynamics and actually require competing feedback mechanisms to improve their controllability.

[0004] On the other hand, for difficult-to-process materials (such as superhard materials, metallic glasses, and other materials whose properties are easily altered), current conventional surface modification techniques are still insufficient to meet their processing requirements, limiting the further application of these high-performance materials. Therefore, a new processing scheme is needed to achieve practical functions such as low cost, high throughput, scalable large area, and low collateral damage. In addition, regarding surface properties in the infrared band involving optical modulation and liquid manipulation, traditional techniques (such as coating / electroplating, multilayer film structures, etc.) require adding new materials to the parent material, most of which are complex processes and environmentally unfriendly. Ultrafast laser technology, which directly prints functional micro / nano structure surfaces onto raw materials, is expected to have advantages in the fabrication of lightweight, robust, and easily scalable surfaces. Summary of the Invention

[0005] The purpose of this invention is to provide a method for rapidly preparing functionalized self-arrayed micro / nanoporous surfaces directly on the surface of ultrahard metals or alloys.

[0006] This invention provides a method for rapidly fabricating functionalized self-arrayed micro / nanopore surfaces directly on the surface of ultra-hard metals or alloys. Utilizing femtosecond laser direct writing technology, it rapidly forms functionalized micro / nanostructure surfaces while preserving the characteristic properties of the raw materials. Applicable ultra-hard alloys or metals include, but are not limited to, metallic glasses, tungsten, and chromium. The pores of the ultrawavelength self-arrayed micro / nanopores are approximately circular, with a diameter consistently larger than the laser wavelength used, adjustable within the range of 500 nm to 6 μm, and the spacing adjustable within the range of 1 to 5 μm. The pores exhibit good periodicity and regularity.

[0007] The method for fabricating functionalized self-arrayed micro / nano-hole surfaces using femtosecond laser direct writing provided by this invention, based on the principle of near-field optical modulation, comprises the following specific steps:

[0008] First, an ultrafast laser is used to scan the surface of an ultrahard metal or alloy 15 to 20 times to induce the formation of a striped SWPSS groove structure.

[0009] Subsequently, the laser spot is offset by a distance of 5–12 μm along the direction perpendicular to the scanning path on the formed SWPSS trench structure, and scanning is continued for 15–20 times; a row of neatly arranged micro / nanopores is formed at the center of the two scanning trajectories.

[0010] Subsequently, the above process is repeated, with each scanning trajectory overlapping and scanning at the same offset spacing, ultimately forming rows of neatly arranged self-arrayed micro / nanopores.

[0011] The ultrafast laser has a spot diameter of 8–25 μm, a pulse width of 300 fs, a power of 23–58 mW, a scanning speed of 25–100 mm / s, a repetition frequency of 10 kHz, and a laser wavelength of 340 nm–1030 nm.

[0012] Furthermore, the laser wavelength can be selected from 1030 nm, 515 nm, and / or 343 nm. A 1030 nm laser wavelength can fabricate self-arrayed micro-holes with an aperture of 3–6 μm, corresponding to a spot diameter of 25 μm and an offset distance of 10–12 μm; a 515 nm laser wavelength can fabricate self-arrayed micro-holes with an aperture of 1–3 μm, corresponding to a spot diameter of 16 μm and an offset distance of 7–9 μm; and a 343 nm laser wavelength can fabricate self-arrayed micro-holes with an aperture of 500 nm–1 μm, corresponding to a spot diameter of 8 μm and an offset distance of 5–7 μm. The micro / nano-holes in this invention do not require individual drilling with an ultrafast laser; they can spontaneously form at the center of the intersecting scanning trajectories simply by using rapid ultrafast laser scanning.

[0013] In this invention, Fourier transform infrared spectroscopy was used to measure and compare the infrared reflectance of self-arrayed micro / nanopores and conventional micro / nanopores (with irregularly arranged pores), LIPSS micro / nanostructures, and polished and unpolished surfaces. In the 2.5–6.5 μm wavelength range, compared to other surfaces, the infrared reflectance of the self-arrayed micro / nanopore surface fabricated in this invention decreased from approximately 80% to approximately 5%. In the 6.5–16 μm wavelength range, compared to other surfaces, the infrared reflectance of the self-arrayed micro / nanopore surface fabricated in this invention decreased from approximately 80% to approximately 15%. Figure 3 As shown.

[0014] In this invention, an infrared thermal imaging camera (Hikmicro) is used to capture infrared thermal images of the samples. Infrared thermal imaging was performed on the original sample, the polished sample, the LIPSS surface sample, and the self-arrayed micro / nanopore surface sample fabricated according to this invention. Compared to other samples, the self-arrayed micro / nanopore surface sample fabricated according to this invention exhibits excellent anti-reflection properties, such as... Figure 4 As shown. Furthermore, infrared thermographic images of samples with self-arrayed micro / nanoporous surfaces were captured at shooting angles of 15°, 30°, 60°, and 90°. At different shooting angles, the micro / nanoporous surface consistently maintained good anti-reflective properties, such as... Figure 5 As shown.

[0015] In this invention, the micro / nanopore surface exhibits excellent radiative cooling and self-cooling capabilities due to its low infrared reflectivity (i.e., high infrared emissivity) at 8–13 μm. After heating to 90°C and cooling for 60 s, the temperature of the self-arrayed micro / nanopore surface decreased by approximately 7–8°C compared to other surfaces. Figure 6 As shown.

[0016] In this invention, the self-arrayed micro / nanoporous surface exhibits excellent hydrophobic-oleophobic properties. Compared to the original alloy or metal surface, the water contact angle of the self-arrayed micro / nanoporous surface increases from 76.6° to 102.2°; the oil contact angle increases from 18.3° to 32.2°, as shown below. Figure 7 As shown.

[0017] This invention also fabricated self-arrayed micro / nanoporous structures on the surfaces of ultrahard metals tungsten and chromium, demonstrating the versatility of this technology, such as... Figure 8 As shown.

[0018] In summary, the self-arrayed micro / nanopore surface prepared by this invention has properties such as infrared anti-reflection, self-cooling and heat dissipation, hydrophobicity, and oleophobicity, and can be applied to outdoor radiative cooling, self-lubrication of bearing structural components in extreme environments, and other scenarios. Attached Figure Description

[0019] Figure 1 This invention presents a mechanism diagram and scanning strategy diagram for rapidly inducing self-arrayed micro / nanopore surfaces via laser scanning.

[0020] Figure 2 This is a SEM image of the self-arrayed micro / nanopore structure obtained by this invention.

[0021] Figure 3 This invention compares the infrared reflectance curves of the self-arrayed micro / nanopore surface with those of conventional micro / nanostructure surfaces.

[0022] Figure 4 These are infrared thermal images of the surface of the self-arrayed micro / nanopores and the surface of conventional micro / nano structures obtained by this invention.

[0023] Figure 5 This invention provides infrared thermal images of the self-arrayed micro / nanopore surface and the conventional micro / nano structure surface at different shooting angles.

[0024] Figure 6 This is a graph showing the heat dissipation effect of the self-arrayed micro / nanopore surface and the conventional micro / nano structure surface measured by the present invention over 60 seconds.

[0025] Figure 7 This invention provides the water-oil contact angle test results obtained from the surface of the self-arrayed micro / nanopore and the surface of conventional micro / nanostructures.

[0026] Figure 8 This invention relates to a self-arrayed micro / nanoporous structure fabricated on ultra-hard metals tungsten and chromium. Detailed Implementation

[0027] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0028] Example 1: For Zr-based metallic glass (Zr52.5Ni14.6Al10Cu17.9Ti5), a self-arrayed micro / nanopore surface was fabricated using an ultrafast laser misalignment scanning strategy, such as... Figure 2 As shown in the figure, the ultrafast laser has a spot size of 25 μm, a pulse width of 300 fs, a power of 23–27 mW, a scanning speed of 60–100 mm / s, a repetition rate of 10 kHz, and laser wavelengths of 1030 nm, 515 nm, and / or 343 nm. A 1030 nm laser wavelength can fabricate self-arrayed micro-pores with apertures of 3–6 μm, a 515 nm laser wavelength can fabricate self-arrayed micro-pores with apertures of 1–3 μm, and a 343 nm laser wavelength can fabricate self-arrayed micro-pores with apertures of 500 nm–1 μm. The self-arrayed micro / nanopore surfaces exhibit excellent anti-infrared reflection properties. In the 2.5–6.5 μm wavelength range, the infrared reflectivity of the self-arrayed micro / nanopore surfaces decreases from approximately 80% to approximately 5%. In the 6.5–16 μm wavelength range, the infrared reflectivity of the self-arrayed micro / nanopore surfaces decreases from approximately 80% to approximately 15%. Infrared thermal imaging of the self-arrayed micro / nanoporous surface revealed its excellent anti-infrared reflection properties, unaffected by the shooting angle. Furthermore, after heating to 90°C and cooling for 60 seconds, the temperature of the self-arrayed micro / nanoporous surface decreased by approximately 7–8°C compared to other surfaces, demonstrating good cooling and heat dissipation effects. Compared to conventional surfaces, the water contact angle of the self-arrayed micro / nanoporous surface increased by 25.6°, and the oil contact angle increased by 13.9°. This surface area exhibits hydrophobic and oleophobic properties.

[0029] Example 2: For pure tungsten metal, a self-arrayed micro / nanopore surface was fabricated using an ultrafast laser misalignment scanning strategy, such as... Figure 8As shown, the ultrafast laser has a spot size of 25 μm, a pulse width of 300 fs, a power of 52–60 mW, a scanning speed of 20–30 mm / s, a repetition rate of 10 kHz, and laser wavelengths of 1030 nm, 515 nm, or 343 nm. A 1030 nm laser wavelength can fabricate self-arrayed micropores with apertures of 3–6 μm, a 515 nm wavelength can fabricate self-arrayed micropores with apertures of 1–3 μm, and a 343 nm wavelength can fabricate self-arrayed micropores with apertures of 500 nm–1 μm. The self-arrayed micro / nanopore surface exhibits excellent anti-infrared reflection properties. In the 2.5–6.5 μm wavelength range, the infrared reflectivity of the self-arrayed micro / nanopore surface decreases from approximately 80% to approximately 5%. In the 6.5–16 μm wavelength range, the infrared reflectivity of the self-arrayed micro / nanopore surface decreases from approximately 80% to approximately 15%. Infrared thermal imaging of the self-arrayed micro / nanoporous surface revealed its excellent anti-infrared reflection properties, unaffected by the shooting angle. Furthermore, after heating to 90°C and cooling for 60 seconds, the temperature of the self-arrayed micro / nanoporous surface decreased by approximately 7–8°C compared to other surfaces, demonstrating good cooling and heat dissipation effects. Compared to conventional surfaces, the water contact angle of the self-arrayed micro / nanoporous surface increased by 25.6°, and the oil contact angle increased by 13.9°. This surface area exhibits hydrophobic and oleophobic properties.

[0030] Example 3: For pure chromium metal, a self-arrayed micro / nanopore surface was fabricated using an ultrafast laser misaligned scanning strategy, such as... Figure 8As shown, the ultrafast laser has a spot size of 25 μm, a pulse width of 300 fs, a power of 40–48 mW, a scanning speed of 25–35 mm / s, a repetition frequency of 10 kHz, and laser wavelengths of 1030 nm, 515 nm, or 343 nm. A 1030 nm laser wavelength can fabricate self-arrayed micropores with apertures of 3–6 μm, a 515 nm wavelength can fabricate self-arrayed micropores with apertures of 1–3 μm, and a 343 nm wavelength can fabricate self-arrayed micropores with apertures of 500 nm–1 μm. The self-arrayed micro / nanopore surface exhibits excellent anti-infrared reflection properties. In the 2.5–6.5 μm wavelength range, the infrared reflectivity of the self-arrayed micro / nanopore surface decreases from approximately 80% to approximately 5%. In the 6.5–16 μm wavelength range, the infrared reflectivity of the self-arrayed micro / nanopore surface decreases from approximately 80% to approximately 15%. Infrared thermal imaging of the self-arrayed micro / nanoporous surface revealed its excellent anti-infrared reflection properties, unaffected by the shooting angle. Furthermore, after heating to 90°C and cooling for 60 seconds, the temperature of the self-arrayed micro / nanoporous surface decreased by approximately 7–8°C compared to other surfaces, demonstrating good cooling and heat dissipation effects. Compared to conventional surfaces, the water contact angle of the self-arrayed micro / nanoporous surface increased by 25.6°, and the oil contact angle increased by 13.9°. This surface area exhibits hydrophobic and oleophobic properties.

Claims

1. A method for fabricating functionalized self-arrayed micro / nano-pore surfaces using femtosecond laser direct writing, characterized in that, The specific steps are as follows: (1) Use an ultrafast laser to scan the surface of an ultrahard metal or alloy 15 to 20 times to induce the formation of a striped SWPSS groove structure. (2) On the formed SWPSS trench structure, the laser spot is offset by 5~12 μm along the direction perpendicular to the scanning path, and the scanning continues for 15~20 times; a row of neatly arranged micro / nanopores is formed at the center of the two scanning tracks; (3) Repeat the above steps (1) and (2), and each scanning trajectory is overlapped and scanned according to the same offset distance, so as to form a series of neatly arranged self-array micro / nanopores. The self-arrayed micro / nanopores have a pore shape similar to a circle, with a pore diameter larger than the laser wavelength used, which is adjustable in the range of 500 nm to 6 μm. The pore spacing is adjustable in the range of 1 to 5 μm, and the pores exhibit periodicity and regularity. The ultrafast laser has a spot diameter of 8~25μm, a pulse width of 300 fs, a power of 23~58 mW, a scanning speed of 25~100 mm / s, a repetition frequency of 10 kHz, and a laser wavelength of 340 nm~1030 nm.

2. The method according to claim 1, characterized in that, The laser wavelength is 1030 nm, 515 nm, or 343 nm; the 1030 nm laser wavelength is used to fabricate self-arrayed micropores with an aperture of 3-6 μm, corresponding to a spot diameter of 25 μm and an offset distance of 10-12 μm; the 515 nm laser wavelength is used to fabricate self-arrayed micropores with an aperture of 1-3 μm, corresponding to a spot diameter of 16 μm and an offset distance of 7-9 μm; the 343 nm laser wavelength is used to fabricate self-arrayed micro / nanopores with an aperture of 500 nm-1 μm, corresponding to a spot diameter of 8 μm and an offset distance of 5-7 μm.

3. The method according to claim 1, characterized in that, The superhard metal is tungsten or chromium, and the alloy is metallic glass.

4. A functionalized self-arrayed micro / nanoporous surface prepared by the method according to any one of claims 1-3, characterized in that, The aperture is larger than the laser wavelength used and is adjustable in the range of 500 nm to 6 μm. The aperture spacing is adjustable in the range of 1 to 5 μm. The apertures exhibit periodicity and regularity. The self-arrayed micro / nanopore surface has infrared anti-reflection and self-cooling heat dissipation properties.

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