NANOSECOND LASER ABLATION AND CHEMICAL THERMAL DECOMPOSITION COMBINED METHOD FOR PREPARING SUPER-HYDROPHOBIC MICRO-NANO STRUCTURE ON STAINLESS STEEL SURFACES

Abstract

A nanosecond laser ablation and chemical thermal decomposition for preparing a super-hydrophobic micro-nano structure on stainless steel. The method solves the defects of long preparation cycle and complex process flow of a super-hydrophobic surface of stainless steel, and does not use fluorine-containing chemical reagents for modification. The method includes: ultrasonically cleaning a stainless steel sample piece in absolute ethanol and air-drying at room temperature; performing primary infrared nanosecond laser ablation on the sample piece to obtain a micro-nano structure; evenly coating a surface of the workpiece with micro-droplets of a stearic acid ethanol solution by using an ultrasonic atomizer; performing secondary infrared nanosecond laser ablation on the sample piece; and ultrasonically cleaning the sample piece with acetone, absolute ethanol, and deionized water respectively for 10 minutes to remove undecomposed stearic acid and slag, thereby obtaining a stainless steel super-hydrophobic surface with stable super-hydrophobic property and good quality.

Claims

1. A nanosecond laser ablation and chemical thermal decomposition combined method for preparing a super-hydrophobic micro-nano structure on stainless steel surfaces, comprising: pretreating stainless steel; performing laser ablation on the pretreated stainless steel to form a micro-nano structure; depositing stearic acid micro-nano particles on the micro-nano structure; performing secondary laser ablation to decompose the stearic acid; and preforming after-treatment.

2. The nanosecond laser ablation and chemical thermal decomposition combined method for preparing a super-hydrophobic micro-nano structure on stainless steel surfaces according to claim 1, wherein the pretreatment comprises cleaning, impurity removal, and air drying.

3. The nanosecond laser ablation and chemical thermal decomposition combined method for preparing a super-hydrophobic micro-nano structure on stainless steel surfaces according to claim 1, wherein the laser ablation adopts infrared nanosecond laser pulses.

4. The nanosecond laser ablation and chemical thermal decomposition combined method for preparing a super-hydrophobic micro-nano structure on stainless steel surfaces according to claim 1, wherein parameters of the laser ablation are that an average nanosecond laser power is 5-20 W, a pulse frequency is 20-200 kHz, a scanning speed is 100-2000 mm/min, and a scanning interval is 20-100 μm.

5. The nanosecond laser ablation and chemical thermal decomposition combined method for preparing a super-hydrophobic micro-nano structure on stainless steel surfaces according to claim 1, wherein a method of depositing stearic acid micro-nano particles comprises: ultrasonically atomizing a stearic acid ethanol solution, evenly coating a surface of the workpiece with a layer of micro-droplets of the stearic acid ethanol solution, evaporating the ethanol, and depositing the stearic acid micro-nano particles on the surface of the micro-nano structure.

6. The nanosecond laser ablation and chemical thermal decomposition combined method for preparing a super-hydrophobic micro-nano structure on stainless steel surfaces according to claim 1, wherein a mass ratio of stearic acid to ethanol in the stearic acid ethanol solution is 2%-4%.

7. The nanosecond laser ablation and chemical thermal decomposition combined method for preparing a super-hydrophobic micro-nano structure on stainless steel surfaces according to claim 1, wherein a moving speed of an ultrasonic atomization device is 1000-2000 mm/min, a distance from the surface of the workpiece is 25-35 mm, and an interval between two sprays is 4-6 mm.

8. The nanosecond laser ablation and chemical thermal decomposition combined method for preparing a super-hydrophobic micro-nano structure on stainless steel surfaces according to claim 1, wherein parameters of the secondary laser ablation are that an average laser power is 0.1-1 W, a pulse frequency is 20-200 kHz, a scanning speed is 1000-2000 mm/min, and a scanning interval is 20-100 μm.

9. Stainless steel with a super-hydrophobic micro-nano structure on the surface, prepared by the method according to claim 1.

10. Application of the stainless steel with a super-hydrophobic micro-nano structure on the surface according to claim 9 in the fields of medical equipment, ships, and aerospace.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings constituting a part of this application are used for providing further understanding for this application. Exemplary embodiments of this application and descriptions thereof are used for explaining this application and do not constitute any inappropriate limitation to this application.

[0029] FIG. 1 is a schematic diagram of a nanosecond laser ablation and chemical thermal decomposition combined method for preparing a super-hydrophobic micro-nano structure on stainless steel surfaces of Embodiment 1 of the present invention.

[0030] FIG. 2 is a three-dimensional morphology diagram of a 316L stainless steel sample piece processed by the preparation method of Embodiment 1 of the present invention.

[0031] FIG. 3 shows the static contact angle of the surface of an unprocessed 316L stainless steel sample piece in Comparative example 1.

[0032] FIG. 4 shows the static contact angle of a 316L stainless steel sample piece only subjected to laser processing in step 1 in Comparative example 2.

[0033] FIG. 5 shows the static contact angle of the surface of the 316L stainless steel prepared in Embodiment 1 of the present invention.

[0034] In the figures, 1 represents infrared nanosecond laser pulse, 2 represents laser focusing lens, 3 represents 316L stainless steel sample piece, 4 represents stearic acid particles, 5 represents micro-droplets of stearic acid ethanol solution, 6 represents ultrasonic atomizer, 7 represents stearic acid ethanol solution, and 8 represents carbide.

DETAILED DESCRIPTION

[0035] It should be noted that, the following detailed descriptions are exemplary, and are intended to provide a further description to this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs.

[0036] It should be noted that terms used herein are only for the purpose of describing specific implementations and are not intended to limit the exemplary implementations of this application. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise. In addition, it should further be understood that terms “comprise” and/or “include” used in this specification indicate that there are features, steps, operations, devices, components, and/or combinations thereof.

[0037] As introduced in the related art, the current preparation method of the surface super-hydrophobic micro-nano structure has the problem of long cycle or environmental pollution. Therefore, the present invention provides a nanosecond laser ablation and chemical thermal decomposition combined method for preparing a super-hydrophobic micro-nano structure on a stainless steel surface, including the following steps:

[0038] Step (1): Pretreatment: a stainless steel sample piece is cleaned ultrasonically with absolute ethanol to remove surface oil stains and impurities, and air-dried at room temperature.

[0039] Step (2): The workpiece cleaned and air-dried in step 1 is placed on an infrared nanosecond laser processing platform; a laser focus is adjusted to an upper surface of the workpiece, and linear scanning is performed at equal intervals according to the laser power, frequency, scanning speed and interval required by an experiment.

[0040] Step (3): An ethanol solution of stearic acid is prepared, the solution is poured into an ultrasonic atomizer, the ultrasonic atomizer is started, a layer of microdroplets of the stearic acid ethanol solution is evenly coated on the surface of the workpiece, and the ethanol is quickly evaporated, so that stearic acid micro-nano particles are deposited on the surface of the micro-nano structure.

[0041] Step (4): Laser power is reduced, laser processing is performed again using the program code in step 2, and the stearic acid decomposes by the heat of laser ablation, so that the surface carbon content is increased, and the surface energy is reduced.

[0042] Step (5): After-treatment: the sample piece obtained in step 4 is ultrasonically cleaned with acetone, absolute ethanol, and deionized water respectively, so as to remove the undecomposed stearic acid and slag produced by laser ablation adhered to the surface, and obtain a stainless steel surface with a stable super-hydrophobic property.

[0043] Preferably, the ultrasonic cleaning time with absolute ethanol in step (1) is 5 minutes.

[0044] Preferably, in step (2), the average laser power is 20 W, the pulse frequency is 100 kHz, the scanning speed is 2000 mm/min, and the scanning interval is 25-50 μm.

[0045] Preferably, the mass ratio of the stearic acid to the absolute ethanol solution in step (3) is 2%-4%, and the mixed solution is placed in constant temperature water at 70-90° C. to accelerate the dissolution of stearic acid.

[0046] Preferably, in step (4), the average laser power is 0.2 W, the pulse frequency is 100 kHz, the scanning speed is 2000 mm/min, and the scanning interval is the same as that in step (2).

[0047] Preferably, the ultrasonic cleaning time of acetone, absolute ethanol, and deionized water in step (5) is 10 minutes respectively.

[0048] The present invention will be further described in detail below in conjunction with specific embodiments. It should be pointed out that the specific embodiments are for explaining rather than limiting the present invention.

Embodiment 1

[0049] (1) Pretreatment: a 10 mm×10 mm×2 mm stainless steel sample was ultrasonically cleaned in absolute ethanol for 5 minutes to remove surface oil stains and impurities, and air dried at room temperature.

[0050] (2) Primary ablation with infrared nanosecond laser: referring to FIG. 1, the pretreated workpiece was placed on an infrared nanosecond laser processing platform; the laser focus was adjusted to the upper surface of the workpiece, and the parameters were set as that the average laser power was 20 W, the pulse frequency was 100 kHz, the scanning speed was 2000 mm/min, and the laser scanning interval was 25 μm.

[0051] (3) Deposition of stearic acid particles: referring to FIG. 1, an absolute ethanol solution of stearic acid with the mass ratio of 3% was atomized using an ultrasonic atomization device, a layer of micro-droplets of the stearic acid ethanol solution was evenly sprayed on the surface of the sample piece, where the moving speed of the ultrasonic atomization device was 2000 mm/min, the distance from the surface of the workpiece was 30 mm, and the interval between two sprays was 5 mm.

[0052] (4) Secondary ablation with infrared nanosecond laser: referring to FIG. 1, the average laser power was 0.2 W, the pulse frequency was 100 kHz, the scanning speed was 2000 mm/min, and the laser scanning interval was 25 μm.

[0053] (5) Sample piece cleaning: the obtained sample piece was ultrasonically cleaned with acetone, absolute ethanol, and deionized water respectively for 10 minutes, so as to remove the undecomposed stearic acid and the slag produced by laser ablation adhered to the surface. The super-hydrophobic micro-nano structure of the 316L stainless steel prepared in Embodiment 1 is shown in FIG. 2, and the contact angle of the sample piece is shown in FIG. 5, which is 162°.

COMPARATIVE EXAMPLE 1

[0054] The difference between this comparative example and Embodiment 1 is that only step (1) is adopted. The contact angle of the smooth stainless steel sample piece of Comparative example 1 is shown in FIG. 3, and the contact angle is 78°.

COMPARATIVE EXAMPLE 2

[0055] The difference between this comparative example and Embodiment 1 is that only steps (1), (2) and (5) are adopted, and steps (3) and (4) are omitted. The contact angle of the sample piece prepared in Comparative example 2 is shown in FIG. 4, and the contact angle is 32°.

[0056] The trademark of the stainless steel material used in the present embodiment and the comparative examples is 316L.

[0057] It should be finally noted that, the foregoing descriptions are merely preferred embodiments of the present invention, but are not intended to limit the present invention.

[0058] Although the present invention is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they may still make modifications to the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention. The specific implementations of the present invention are described above with reference to the accompanying drawings, but are not intended to limit the protection scope of the present invention. Those skilled in the art should understand that various modifications or deformations may be made without creative efforts based on the technical solutions of the present invention, and such modifications or deformations shall fall within the protection scope of the present invention.