CN114558764A - A kind of efficient superhydrophobic surface preparation method - Google Patents

Abstract

The invention relates to a method for preparing an efficient super-hydrophobic surface, comprising the following steps: step 10) cleaning the substrate: cleaning the metal substrate; step 20) laser micro-nano processing: placing the cleaned substrate in an ultraviolet nanosecond laser processing system On the sample stage, use a laser beam to process the micro-nano structure on the surface of the metal substrate, and then ultrasonically clean it in isopropanol for 5 to 10 minutes; step 30) Silicone oil treatment: drop 15 ~25 μL of a mixed solution of dimethyl silicone oil and isopropanol; step 40) low temperature heat treatment: heating the metal substrate treated in step 30) on a heating plate for 5 to 10 minutes, then taking it out and using isopropanol for ultrasonic cleaning, Finally, it was dried in a nitrogen stream to obtain a superhydrophobic surface. The method of the invention improves the preparation efficiency, reduces the preparation cost and ensures no toxicity to the organism and the environment.

Description

A kind of efficient superhydrophobic surface preparation method

technical field

The invention relates to the technical field of material processing engineering, in particular to a method for preparing an efficient super-hydrophobic surface.

Background technique

Based on the excellent properties of self-cleaning, antibacterial, corrosion resistance, drag reduction, and anti-icing exhibited by superhydrophobic surfaces, they have been widely used in rail transit, petroleum equipment, aerospace, and medical and health fields.

In the prior art, the main methods for preparing superhydrophobic surfaces include low surface energy material coating, self-assembly, polymer imprinting, electrospinning, etching, and laser processing. Among them, the laser processing method is widely used due to its advantages of high process flexibility, high degree of automation, low environmental pollution and high preparation precision. However, preparation efficiency is still a major problem faced by laser processing methods in actual industrial production, which is mainly due to the following reasons: 1. Most laser surface treatment processes require the use of small spots and repeated scans, so that the laser processing itself The preparation efficiency is low; 2. The surface after laser treatment shows super-hydrophilic properties. In order to realize the transformation of the surface from superhydrophilic to superhydrophobic properties, the surface needs to be placed in air for 3-7 days. The superhydrophobicity can be achieved by depositing the hydrophobic groups in the air on the surface, which greatly increases the preparation cycle of the superhydrophobic surface. 3. The transformation of the laser-treated surface from superhydrophilic to superhydrophobic can be accelerated by some post-processing processes, but these post-processing processes also take several hours. At the same time, some methods such as chemical infiltration methods require the use of fluorine-containing chemical reagents, and their high chemical toxicity also limits their application in biomedicine and other fields.

In conclusion, it is urgent to develop a high-efficiency, low-cost and non-toxic superhydrophobic surface preparation process.

SUMMARY OF THE INVENTION

Aiming at the deficiencies of the prior art, the present invention provides a method for preparing an efficient superhydrophobic surface, so as to improve the preparation efficiency.

The technical scheme adopted in the present invention is as follows:

An efficient superhydrophobic surface preparation method, comprising:

Step 10) cleaning the substrate: cleaning the metal substrate;

Step 20) Laser micro-nano processing: place the cleaned metal substrate on the sample stage of the ultraviolet nanosecond laser processing system, use the laser beam to process the micro-nano structure on the surface of the metal substrate, and then ultrasonically clean it in isopropyl alcohol 5 ~10 minutes;

Step 30) Silicone oil treatment: drop a mixed solution of dimethyl silicone oil and isopropanol on the treated metal substrate in step 20);

Step 40) low temperature heat treatment: the metal substrate treated in step 30) is heated on a heating plate, then taken out and ultrasonically cleaned with isopropanol, and finally dried in a nitrogen stream to obtain a superhydrophobic surface.

Further technical solutions are:

The metal substrate is AISI 304 stainless steel, red copper, brass or Ti-6Al-4V titanium alloy.

In the step 10): the metal substrate is sequentially placed in acetone, absolute ethanol, and deionized water for ultrasonic cleaning, and then placed in a nitrogen stream to dry.

In the step 10), the metal substrate is ultrasonically cleaned in acetone, absolute ethanol and deionized water for 10-15 minutes respectively.

In the step 20): the ultraviolet nanosecond laser processing system adopts an ultraviolet nanosecond pulse laser, the laser wavelength is 355nm, the pulse width is 10ns, the pulse repetition frequency is 40～60kHz, the laser power is 5.8～6.5W, and the pulse energy is 0.1 ～0.16mJ, the laser power density is 0.23～0.57GW/cm ² , the effective spot diameter after focusing is about 60m, the laser scanning rate is 5～50mm/s, and the laser beam scanning area is 10mm×10mm.

In the step 20): the surface structure of the micro-nano structure is a unidirectional, annular or cross-shaped micro-scale groove structure, and the micro-scale groove structure is covered with sub-micron or nano-scale sputtering particles; The groove pitch is 100-300 μm, and the groove depth is 15-25 μm.

In the step 30), the volume of the mixed solution dropped in is 15-25 μL, the volume fraction of dimethicone in the mixed solution is 0.2%-0.4%, and the volume fraction of the isopropanol solution is 99.6%-99.8%.

In the step 40), the temperature of the heating plate is 100-150° C., and the heating time is 5-10 minutes.

The beneficial effects of the present invention are as follows:

The invention greatly shortens the preparation period, improves the preparation efficiency and reduces the preparation cost. It also ensures non-toxicity to organisms and the environment.

Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention.

Description of drawings

Fig. 1 is the process flow schematic diagram of the present invention. Among them: 1, laser; 2, attenuator; 3, beam amplifier; 4, galvanometer; 5, cooling system; 6, controller; 7, computer; 8, sample stage; 9, sample; 10, heating plate; a For silicone oil treatment; b for low temperature heat treatment; c for ultrasonic cleaning.

FIG. 2 is the test result of the three-dimensional profile of the surface after the laser micro-nano processing of the present invention.

FIG. 3 is a SEM image of the surface after the laser micro-nano processing of the present invention.

Figure 4 shows the EDS spectra of surfaces prepared by different treatments. Wherein: (a) is the untreated surface; (b) is the surface treated by laser micro-nano processing; (c) is the surface which adopts laser-silicon oil-heat treatment in the present invention.

Figure 5 shows the measurement results of the contact angle of water droplets on surfaces prepared with different treatments. Among them: (a) is the untreated surface; (b) is the surface treated by laser micro-nano processing; (c) is the surface treated with silicone oil after laser micro-nano processing; (d) is the heat-treated surface; The surface treated with silicone oil; (f) is the surface treated by laser-silicon oil-heat treatment in the present invention.

Detailed ways

The specific embodiments of the present invention will be described below with reference to the accompanying drawings.

Please refer to FIG. 1, the preparation method of the high-efficiency superhydrophobic surface of the present application includes the following steps:

Step 10) Cleaning the metal substrate: the metal substrate is placed in acetone, absolute ethanol, and deionized water for ultrasonic cleaning in sequence, and then placed in a nitrogen stream to dry.

Step 20) Laser micro-nano processing: place the cleaned metal substrate on the sample stage of the ultraviolet nanosecond laser processing system, use the laser beam to process the micro-nano structure on the surface of the metal substrate, and then ultrasonically clean it in isopropyl alcohol 5 ~10 minutes;

Step 30) Silicone oil treatment: drop a mixed solution of dimethyl silicone oil and isopropanol on the treated metal substrate in step 20);

Step 40) low temperature heat treatment: the metal substrate treated in step 30) is heated on a heating plate, then taken out and ultrasonically cleaned with isopropanol, and finally dried in a nitrogen stream to obtain a superhydrophobic surface.

The metal base is AISI 304 stainless steel, copper, brass or Ti-6Al-4V titanium alloy, etc.

The preparation method of the present application mainly includes two process steps: laser micro-nano processing and post-processing.

The laser processing equipment adopts the TH-UV200A ultraviolet nanosecond laser processing platform produced by Suzhou Tianhong Laser Company, and the laser is the ultraviolet nanosecond pulse laser AWAVE 355-15W-30K produced by Advanced Optowave Company. As shown in Figure 1, put the sample 9 on the sample stage 8, the laser beam is emitted by the laser 1, through the attenuator 2 and the beam amplifier 3, after entering the galvanometer 4, the computer 7 software is connected to the controller 6 to realize the scanning of the laser beam Pattern control. The galvanometer 4 is connected to the cooling system 5 .

Among them, the laser wavelength is 355nm, the pulse width is 10ns, the pulse repetition frequency is 40～60kHz, the laser power is 5.8～6.5W, the pulse energy is 0.1～0.16mJ, and the laser power density is 0.23～0.57GW/cm ² . The effective spot diameter is about 60 μm, the laser scanning rate is 5-50 mm/s, and the laser beam scanning area is 10 mm × 10 mm.

Specifically, in the post-treatment of the silicone oil, 15-25 μL of the mixed solution is dropped, and the volume fraction of the dimethicone oil in the mixed solution is 0.2%-0.4%, and the volume fraction of the isopropanol solution is 99.6%-99.8%. The temperature of the heating plate 10 used in the low-temperature heat treatment is 100 to 150° C., and the heating time is 5 to 10 minutes.

The method for preparing a high-efficiency superhydrophobic surface of the present application will be further described below through specific examples.

Example 1:

Step 10) Cut the copper substrate to a size of 10mm×10mm, then ultrasonically clean it with acetone, anhydrous ethanol, and deionized water for 10 minutes in turn to remove contaminants on the surface of the substrate, and then place it in a nitrogen stream to dry.

Step 20) Perform laser micro-nano processing on the surface, and the selected laser parameters are as follows: the pulse width is 10ns, the laser wavelength is 355nm, the pulse repetition frequency is 40kHz, the laser power is 6.5W, the pulse energy is 0.16mJ, and the laser power density is is 0.57GW/cm ² , the effective spot diameter after focusing is about 60 μm, the laser scanning rate is 50 mm/s, and the laser beam scanning area is 8 mm×8 mm. The laser-prepared substrates were placed in isopropanol for ultrasonic cleaning for 5 min.

Step 30) Drop 15 μL of a mixed solution of 0.2% dimethyl silicone oil and 99.8% isopropanol by volume on the metal substrate treated in step 20).

Step 40) The metal substrate treated in step 30) is heated on a heating plate for 10 minutes, then taken out and ultrasonically cleaned with isopropanol, and finally dried in a nitrogen stream to obtain a superhydrophobic surface.

Put 5 μL of deionized water on the surface after step 20), the contact angle of water droplets is 0°, showing super-hydrophilic properties; 156.3°, showing excellent superhydrophobicity.

Example 2:

Step 10) Cut the 304 stainless steel substrate to a size of 15mm×15mm, then use acetone, anhydrous ethanol, and deionized water for ultrasonic cleaning for 12 minutes in sequence to remove contaminants on the surface of the substrate, and then place it in a nitrogen stream to dry.

Step 20) Perform laser micro-nano processing on the surface, and the selected laser parameters are as follows: the pulse width is 10ns, the laser wavelength is 355nm, the pulse repetition frequency is 60kHz, the laser power is 5.8W, the pulse energy is 0.1mJ, and the laser power density is is 0.23GW/cm ² , the effective spot diameter after focusing is about 60 μm, the laser scanning rate is 20 mm/s, and the laser beam scanning area is 12 mm×12 mm. The laser-prepared substrates were placed in isopropanol for ultrasonic cleaning for 10 min.

Step 30) Drop 20 μL of a mixed solution of 0.4% dimethyl silicone oil and 99.6% isopropanol by volume on the metal substrate treated in step 20).

Step 40) The metal substrate treated in step 30) is heated on a heating plate for 5 minutes, then taken out and ultrasonically cleaned with isopropanol, and finally placed in a nitrogen stream to dry to obtain a superhydrophobic surface.

5gL of deionized water was still on the surface after step 20), and the contact angle of the water droplet was 0°, showing super-hydrophilic properties; 5 μL of deionized water was still on the surface after step 40), and the water droplet contact angle was as high as 159.2°, showing excellent superhydrophobicity.

Example 3:

Step 10) The Ti-6Al-4V substrate was cut out to a size of 20mm×20mm, and then ultrasonically cleaned with acetone, absolute ethanol, and deionized water for 15 minutes to remove the pollutants on the surface of the substrate, and then placed in a nitrogen stream to dry. .

Step 20) Perform laser micro-nano processing on the surface. The selected laser parameters are as follows: the pulse width is 10ns, the laser wavelength is 355nm, the pulse repetition frequency is 50kHz, the laser power is 6.1W, the pulse energy is 0.12mJ, and the laser power density is is 0.43GW/cm ² , the effective spot diameter after focusing is about 60 μm, the laser scanning rate is 10 mm/s, and the laser beam scanning area is 15 mm×15 mm. The laser-prepared substrates were placed in isopropanol for ultrasonic cleaning for 8 min.

Step 30) Drop 25 μL of a mixed solution of 0.3% dimethyl silicone oil and 99.7% isopropanol by volume on the metal substrate treated in step 20).

Step 40) The metal substrate treated in step 30) is heated on a heating plate for 8 minutes, then taken out and ultrasonically cleaned with isopropanol, and finally dried in a nitrogen stream to obtain a superhydrophobic surface.

Put 5 μL of deionized water on the surface after step 20), the contact angle of water droplets is 0°, showing super-hydrophilic properties; 154.6°, showing excellent superhydrophobicity.

The technical effects achieved by the preparation method of the present application are analyzed below.

1. In terms of surface structure, as shown in FIG. 2 , it is the three-dimensional contour of the surface after the laser micro-nano processing of the present application. As can be seen from Figure 2, through the laser micro-nano processing, the surface exhibits a regularly arranged intersecting micron-scale groove structure. By scanning the three-dimensional surface topography, it can be found that the pitch of the grooves is about 150 μm and the depth is about 20 μm.

As shown in FIG. 3 , it is the SEM test result of the surface after laser micro-nano processing in the application. By observing the SEM images of different magnifications, it can be found that some submicron and nanoscale particles are also distributed on the boundary of each laser-induced microgroove. These particles are mainly formed by the local heating, vaporization and ionization of the material surface during the interaction between the laser and the material, resulting in high-pressure plasma expansion and deposition through material ablation and plasma spraying.

This shows that the laser micro-nano processing technology of the present application can induce the generation of multi-level (micron-submicron-nano) micro-nano structures. Compared with the near-infrared nanosecond laser with a wavelength of 1064nm, this application uses an ultraviolet laser with a wavelength of 355nm. In addition to ensuring the precise control of the metal surface structure, it can also reduce the thermal effect in the laser processing process, reduce the heat-affected zone, and prepare High-quality surface multi-level micro-nano structure, thus laying the foundation for the realization of superhydrophobic properties of metal surfaces.

2. In terms of surface chemical properties, as shown in Figure 4, it is the chemical composition results of different surfaces measured by EDS energy spectrometry.

Figure 4(a) shows the results for the untreated surface. As can be seen from Figure 4a, Cu, C and O elements can be detected on the untreated surface. Among them, the Cu element comes from the base material, the O element comes from the oxidation of the surface layer of the base material, and the C element comes from the slight pollution on the surface of the base material. However, the chemical element composition of the laser micro-nano-machined surface (shown in Fig. 4(b)) exhibits a certain change compared to the untreated surface. Except for some changes in the content of elements in the matrix material, the biggest changes come from C and O elements.

Figure 4(b) is the result of laser micro-nano processing of the surface. It can be seen from Figure 4b that the content of C element on the surface decreased significantly after laser micro-nano processing, while the content of O element increased significantly, indicating that laser micro-nano processing not only induces periodic micro-nano structures on the metal surface, but also makes the surface Significant oxidation, resulting in the formation of a large number of hydroxyl (-OH) and carboxyl (-COOH) groups on the surface. For the surface treated with silicon oil and heat treatment after laser micro-nano processing (the laser-silicon oil-heat-treated surface shown in Fig. 4(c)), the chemical composition of the surface has changed significantly compared with the surface treated by laser micro-nano processing.

Figure 4(c) is the result of the laser-silicon oil-heat-treated surface used in this application. It can be seen from Figure 4c that the chemical changes mainly have the following two aspects: one is that the content of C element on the surface of laser-silicon oil-heat treatment increases significantly, and the other is that the existence of Si element is detected on the surface of laser-silicon oil-heat treatment. The increase of C element content is mainly due to the accelerated deposition of non-polar carbon-containing hydrophobic groups (such as -CH2-, -CH3, C=C and other functional groups) in the air on the metal surface by low temperature heat treatment. The Si element comes from the mixed solution of silicone oil and isopropanol dropped on the surface. During the low-temperature heat treatment, the silicon atoms in the mixed solution are fully deposited on the metal surface, forming a silicon-containing film. With the help of carbon-containing hydrophobic groups with hydrophobic properties and silicon-containing films co-deposited on the surface of laser-silicon oil-heat treatment, the superhydrophobicity of the surface is promoted.

3. In terms of surface wettability, as shown in Figure 5, the measurement results of the contact angle of water droplets on the surface prepared by different treatment methods.

Figure 5(a) is an image of the water droplet contact angle of the untreated surface. The measured water droplet contact angle is 82.1±2.5°, which proves that the surface has hydrophilic properties.

Figure 5(b) is an image of the contact angle of water droplets on the surface after laser micro-nano processing. It is measured that the surface contact angle drops to 0°, indicating that the metal surface after laser processing is in a saturated Wenzel state, which makes the surface exhibit significant Super hydrophilic properties. The reasons mainly include the following two points: (1) The laser micro-nano processing significantly increases the micro-roughness of the metal surface, which makes the water droplets change from the unstable Cassie state to the saturated Wenzel state at the laser-induced microstructure composite interface; (2) A large number of hydroxyl groups (-OH) and carboxyl groups (-COOH) generated on the surface are both polar groups and have extremely strong hydrophilic properties, and the increase in their content also leads to the enhancement of surface hydrophilicity.

In addition, the surface contact angles were increased to 76.8±1.8°, 87.2±1.5° and 96.5±1.6°. This shows that both silicone oil treatment and heat treatment can improve the contact angle of the surface to a certain extent, but not enough to make the surface superhydrophobic.

For the laser-silicon oil-heat treatment process used in this application (Fig. 5(f)), the surface contact angle reaches 159.2±2.1°. This shows that laser micro-nano processing, heat treatment and silicone oil treatment are equally important to achieve superhydrophobic properties. Laser micro-nano processing induces multi-level micro-nano structures on the surface, and heat treatment and silicone oil treatment can change the surface chemistry and reduce the surface energy. The combined effect of multi-level surface micro-nano structure and lower surface energy can ensure the superhydrophobicity of the surface.

Fourth, in terms of preparation efficiency, compared with other superhydrophobic surface preparation methods, the preparation efficiency of the present application is greatly improved.

This is mainly reflected in: (1) low surface energy material coating, self-assembly, polymer imprinting, electrospinning, etching and other processing methods are time-consuming and expensive; (2) the laser-treated surface exhibits super-hydrophilicity characteristic. In order to realize the transformation of the surface from superhydrophilic to superhydrophobic, other laser processing methods need to place the surface in the air for 3-7 days to deposit the hydrophobic groups in the air on the surface to realize the superhydrophobicity, or after some hours The treatment process can accelerate the transformation of laser-treated surfaces from superhydrophilic to superhydrophobic properties. (3) While ensuring the efficiency of laser surface treatment (scanning rate up to 1.89cm ² /min), using the post-treatment process of silicone oil treatment, it only takes 5 to 10 minutes to complete the laser treatment surface from super-hydrophilic to super-hydrophilic The transformation of the hydrophobic properties thus greatly improves the preparation efficiency of superhydrophobic surfaces. Meanwhile, the mixed solution of silicone oil and isopropanol used in the present application is non-toxic to organisms and the environment, and is expected to be widely used in many fields.

Claims (8)

1. A preparation method of a high-efficiency super-hydrophobic surface is characterized by comprising the following steps:

step 10) cleaning the substrate: cleaning the metal substrate;

step 20) laser micro-nano processing: placing the cleaned metal substrate on a sample table of an ultraviolet nanosecond laser processing system, processing a micro-nano structure on the surface of the metal substrate by utilizing a laser beam, and then ultrasonically cleaning the metal substrate in isopropanol for 5-10 minutes;

step 30) silicone oil treatment: dripping a mixed solution of dimethyl silicone oil and isopropanol on the metal substrate treated in the step 20);

step 40) low-temperature heat treatment: heating the metal substrate treated in the step 30) on a heating plate, taking out and ultrasonically cleaning the metal substrate by using isopropanol, and finally blowing the metal substrate in nitrogen flow to obtain the super-hydrophobic surface.

2. The method for preparing the high-efficiency superhydrophobic surface according to claim 1, wherein the metal substrate is AISI304 stainless steel, red copper, brass or Ti-6Al-4V titanium alloy.

3. The method for preparing a highly efficient superhydrophobic surface according to claim 1, wherein in the step 10): and sequentially placing the metal substrate in acetone, absolute ethyl alcohol and deionized water for ultrasonic cleaning, and then placing the metal substrate in nitrogen flow for drying.

4. The method for preparing a highly efficient superhydrophobic surface according to claim 1 or 3, wherein in the step 10): and ultrasonically cleaning the metal substrate in acetone, absolute ethyl alcohol and deionized water for 10-15 minutes respectively.

5. The method for preparing a highly efficient superhydrophobic surface according to claim 1, wherein in the step 20): the ultraviolet nanosecond laser processing system adopts an ultraviolet nanosecond pulse laser, the wavelength of the laser is 355nm, the pulse width is 10ns, the pulse repetition frequency is 40-60 kHz, the laser power is 5.8-6.5W, the pulse energy is 0.1-0.16 mJ, and the laser power density is 0.23-0.57 GW/cm²The diameter of an effective light spot after focusing is about 60 mu m, the laser scanning speed is 5-50 mm/s, and the scanning area of a laser beam is 10mm multiplied by 10 mm.

6. The method for preparing a highly efficient superhydrophobic surface according to claim 5, wherein in the step 20): the surface structure of the micro-nano structure is a unidirectional, annular or crossed micron-scale groove structure array, and submicron-scale or nano-scale sputtering particles are covered on the micron-scale groove structure; the distance between the grooves is 100 to 300 μm, and the depth of the grooves is 15 to 25 μm.

7. The method for preparing the high-efficiency superhydrophobic surface according to claim 5, wherein in the step 30), the volume of the dropped mixed solution is 15-25 μ L; the volume fraction of the dimethyl silicone oil in the mixed solution is 0.2-0.4%, and the volume fraction of the isopropanol solution is 99.6-99.8%.

8. The preparation method of the high-efficiency superhydrophobic surface according to claim 5, wherein the temperature of the heating plate in the step 40) is 100-150 ℃ and the heating time is 5-10 minutes.

Images