CN102896425A - Method for rapidly preparing large area nano texture on metal surface by ultrafast laser - Google Patents

Abstract

The invention relates to a method for quickly preparing a large-area nano-texture on a metal surface by using an ultrafast laser, which specifically includes selecting a metal target material of any metal material, fixing it on a sample stage after surface polishing, and then using the ultrafast laser After filters, half-wave plates, and polarizing beamsplitters, it is introduced into the optical light guide table, and is focused on the surface of the metal target by the focusing lens on the optical light guide table, and then relative motion is generated between the sample stage and the optical light guide table. , between the ultrafast laser and the surface of the metal target, the regular periodic nano-texture stripes are directly scanned on the surface of the metal target by overlapping scanning back and forth, which is characterized by the use of the interaction between the ultrafast laser and the metal material , through computer control of the relative movement between the ultrafast laser and the metal target, an optical scan is formed on the surface of the metal target, and a large-area nano-texture is quickly prepared.

Description

Method for rapid preparation of large-area nanotextures on metal surfaces by ultrafast laser

technical field

The invention relates to a method for quickly preparing a large-area nano-texture on a metal surface by using an ultrafast laser. The nano-texture produced by the method has regularity and periodicity, and the period is much shorter than the laser wavelength. The surface nanostructure preparation technology involved in the method belongs to the field of laser micro-nano processing.

Background technique

The unique mesoscopic effect of the special and regular micro-nano structure on the natural biological surface makes it have extraordinary surface properties. For example, the micron-scale protrusions on the surface of the lotus leaf and the nano-scale wax filaments distributed on it make the lotus leaf super-hydrophobic and excellent self-cleaning performance when it comes out of the mud without staining; there are millions of upright toes attached to the gecko. Microvilli, each microvilli has nano-branches at the end, when millions of these microvilli come into contact with the surface of an object, a strong van der Waals force will be generated between them, allowing the gecko to easily hang upside down from the ceiling or wall surface , It can also leave the surface of the object at will; the rough V-shaped folds on the surface of the shark skin can greatly reduce the friction of the water flow, so that the water flow around the body can flow through more efficiently and achieve fast swimming. These surface Wiener structures contain rich physical principles and application values, which attract researchers' high attention to the preparation technology of surface micro-nano structures.

The realization of traditional nanotexturing is mainly realized by photolithography, which has complicated steps and serious pollution. In recent years, with the rapid development of laser technology, especially the development of ultrafast laser technology, new technical means have been added to many scientific research fields. The ultrafast action of ultrashort pulses on the surface of materials leads to many novel extreme nonlinear phenomena and presents many extraordinary properties. The researchers used laser irradiation methods in metals [Opt.Express 17, 20757 (2009)], semiconductors [Appl. Phys. Lett. 89, 033506 (2006)] polymers [APL 100, 041106 (2012)] Materials developed into various nanostructures. However, in practical applications, people pay more attention to the properties and uses of the obtained nanostructures, that is, to truly realize their extraordinary surface properties by obtaining large-area surface nanotextures. Metal materials are closely related to national defense and national production, and play an irreplaceable role. Large-area surface nano-texturization preparation on the surface of metal materials to achieve extraordinary surface properties is of great value and importance to the development of science and technology and the improvement of scientific and technological productivity. significance.

Contents of the invention

The invention aims to provide a large-area periodic nano-texture directly prepared on the metal surface by using an ultrafast laser. The method has simple process, strong operability and no pollution, is applicable to any metal material, and has wide application potential in military defense and national production.

Content of the present invention comprises following concrete steps:

1) Choose a metal target of any metal material, and fix it on the sample stage after surface polishing. The sample stage is a two-dimensional motion stage controlled by computer programming;

2) The ultrafast laser is introduced into the optical light guide table after passing through the filter, half-wave plate, and polarizing beam splitter in sequence, and is focused to the surface of the metal target by the focusing lens on the optical light guide table. The optical light guide table is a computer Two-dimensional motion platform controlled by programming;

3) Select the working mode of fixed optical light guide table and sample stage movement, or optical light guide table movement and fixed sample stage, so that relative motion occurs between the sample stage and optical light guide table. The surface of the target is scanned directly on the surface of the metal target by overlapping back and forth scanning to form regular periodic nano-texture stripes; the overlapping back and forth scanning method is that the optical light guide table or the sample stage first moves horizontally , and then move in the vertical direction, and then continue to move in the horizontal direction, and the nano-textured stripes formed by two consecutive horizontal moves are partially overlapped in the longitudinal direction; repeating this cycle, a large-area nano-texture is prepared.

The ultrafast laser light source is a femtosecond laser or a subpicosecond laser, and the wavelength of the ultrafast laser is adjustable.

The time for forming the large-area nano-texture is controlled by adjusting the relative motion speed between the sample stage and the optical light guide table, and the time for preparing the nano-texture is inversely proportional to the relative motion speed.

The ultrafast laser light source used in the present invention is femtosecond laser or subpicosecond laser, and ultrafast lasers of different wavelengths are used to regulate the period of the prepared nano-texture, and the period of obtaining the nano-texture is sub-laser wavelength.

The core key points in the present invention are: "large area" and "fast". Among them, the key to the realization of "large area" lies in the overlap-type back-and-forth scanning, that is, the computer program is used to control the moving speed of the two-dimensional moving table in two directions and the distance traveled by the moving table to realize the overlapping of scanning nano-textures, thereby Form large-area texturing preparations. "Fast" means abandoning the traditional nano-texture manufacturing methods, such as photolithography, embossing and other complex manufacturing methods, and only by scanning the ultrafast laser directly on the surface of the metal target to obtain a large area. At the same time, the speed of forming large-area nano-textures is controlled by adjusting the relative movement speed between the sample stage and the light guide table.

The important performance index of the nano-texture obtained in the present invention: "aspect ratio" is formed by controlling the laser pulse flux, scanning speed and scanning times.

Beneficial effect

1) Realized the technology of preparing large-area nano-textures on the metal surface, with simple processing technology, strong operability, no pollution, and low cost, and has important application potential in military defense and national production.

2) The method of the present invention directly scans the metal surface to obtain a nano-texture whose period is smaller than the laser wavelength; the aspect ratio of the nano-texture can be realized by optimizing the laser parameters and scanning parameters.

Description of drawings

Figure 1: The technical roadmap for rapid preparation of large-area nanotextures on metal surfaces by ultrafast lasers,

Figure 2: SEM images of large-area nanotextures obtained on the surface of metal tungsten using a 400nm femtosecond laser,

Fig. 3: Flow chart of the method of the present invention.

(1) Ultrafast laser, (2) Filter, (3) Half-wave plate, (4) Polarizing beam splitter, (5) Focusing mirror, (6) Sample stage, (7) Optical light guide stage

Detailed ways

The specific implementation manner of the present invention will be described in further detail below in conjunction with the accompanying drawings.

The ultrafast laser light source used in the implementation of the present invention is a femtosecond laser or a subpicosecond laser. As shown in Figure 1, the laser beam first passes through a filter to filter out stray light; then passes through a half-wave plate and a polarization beam splitter. The function of the half-wave plate and the polarization beam splitter is to adjust the pulse flux of the laser according to the polarization state of the laser; The laser beam finally passes through the focusing mirror and then focuses on the surface of the metal target. Finally, the two-dimensional motion table is controlled by computer programming to scan the nano-texture on the surface of the metal target.

The specific embodiment of the present invention is illustrated by taking the large-area texture formed by the 400nm femtosecond laser on the surface of tungsten metal mentioned in Figure 2 as an example, but this should not limit the protection scope of the present invention.

The horizontal linearly polarized femtosecond laser with a wavelength of 800nm, a repetition rate of 1KHz, and a pulse width of 35fs becomes a femtosecond laser of 400nm after frequency doubling. The 400nm femtosecond laser passes through a filter, a half-wave plate, and a polarizing beamsplitter in sequence, and is then focused onto the surface of a tungsten metal target by a focusing lens with a focal length of 300mm. The laser spot diameter after focusing is 80μm, and the energy density of a single pulse is 0.19mJ /cm ² .

Tungsten metal with a size of 50mm*20mm*5mm is placed on a two-dimensional sample stage and undergoes surface treatment. The two-dimensional sample stage follows the S-shaped overlapping route under the control of the computer, and the optical light guide table is fixed to realize the scanning of the sample. The control program of the sample stage is set as follows: first, the lateral displacement stage runs at a speed of 0.94mm/s, the travel distance is 10mm, and the width of the nano-texture scanned in one direction is 80μm; then the vertical displacement stage moves downward at 7.1mm/s 60 μm, the lateral displacement stage continued to scan at a speed of 0.94 mm/s, and the nano-texture obtained by the two scans had a 20 μm edge to achieve overlap. If this cycle continues, the time required to form a large-area nano-texture with a width of 10mm*1mm on the entire sample target surface is only 266s, and the obtained nano-period is 210nm, which is small in size and greatly saves time and cost.

Claims (3)

1. The method for rapidly preparing large-area nano-textures on metal surfaces with ultra-fast lasers is characterized in that: the method uses ultra-fast lasers to directly scan large-area nano-texture stripes on the surface of metal materials, and the specific steps are: 1) Choose a metal target of any metal material, and fix it on the sample stage after surface polishing. The sample stage is a two-dimensional motion stage controlled by computer programming; 2) The ultrafast laser is introduced into the optical light guide table after passing through the filter, half-wave plate, and polarizing beam splitter in sequence, and is focused to the surface of the metal target by the focusing lens on the optical light guide table. The optical light guide table is a computer Two-dimensional motion platform controlled by programming; 3) Select the working mode of fixed optical light guide table and sample stage movement, or optical light guide table movement and fixed sample stage, so that relative motion occurs between the sample stage and optical light guide table. The surface of the target is scanned directly on the surface of the metal target by overlapping back and forth scanning to form regular periodic nano-texture stripes; the overlapping back and forth scanning method is that the optical light guide table or the sample stage first moves horizontally , and then move in the vertical direction, and then continue to move in the horizontal direction, and the nano-textured stripes formed by two consecutive horizontal moves are partially overlapped in the longitudinal direction; repeating this cycle, a large-area nano-texture is prepared. 2. The method for rapidly preparing large-area nanotextures on metal surfaces with ultrafast laser according to claim 1, characterized in that: the ultrafast laser light source is femtosecond laser or subpicosecond laser, and the ultrafast laser wavelength adjustable. 3. The method for rapidly preparing large-area nano-textures on metal surfaces with ultra-fast laser according to claim 1, characterized in that: the formation of large-area nano-textures is controlled by adjusting the relative motion speed between the sample stage and the optical light guide table The time for preparing nanostructures is inversely proportional to the relative motion speed.

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