Fluorine-free super-hydrophobic anti-icing surface with micro-nano composite structure and preparation method

Abstract

The invention relates to the technical field of material surface super-hydrophobization, in particular to a fluoride-free super-hydrophobic anti-icing surface with a micro-nano composite structure and a preparation method. According to the specific technical scheme, picosecond laser is used for machining the surface of a substrate to form a micro-nano composite structure array, then the machined surface is placed in a drying oven to be subjected to annealing treatment, and the super-hydrophobic performance can be achieved without applying an extra hydrophobic modifier. The contact angle between the surface prepared through the method and water is larger than 160 degrees, and the freezing behavior of liquid drops on the surface can be almost completely inhibited in the low-temperature environment of-5 DEG C. The fluorine-free super-hydrophobic surface is simple in preparation process, high in stability, environmentally friendly, capable of adapting to various base materials and complex curved surfaces, excellent in super-hydrophobic and anti-icing performance and suitable for large-scale preparation and application.

Description

Technical Field

[0001] The present invention relates to the technical field of superhydrophobic modification of material surfaces, and particularly relates to a fluorine-free superhydrophobic anti-icing surface with a micro-nano composite structure and a preparation method thereof. Background Art

[0002] The icing problem of surfaces at low temperatures is widely involved in important fields such as refrigeration equipment, aerospace, wind power generation, and power transmission, and is closely related to people's daily production and life. Surface icing not only reduces the performance and efficiency of equipment, but may even threaten people's lives and property safety in severe cases. Superhydrophobic surfaces can be used as a passive anti-icing and de-icing method, which has the advantages of low cost, low energy consumption, simple system structure and easy implementation, and has broad potential application value.

[0003] Superhydrophobicity is a special surface wetting phenomenon. Generally, the contact angle of water droplets on the surface is greater than 150°, and the rolling angle is less than 10°. The reason for this phenomenon is that the rough structure on the superhydrophobic surface can store air, and the existence of the air cushion greatly reduces the contact area between the water droplet and the surface, making the water droplet nearly spherical on the superhydrophobic surface and extremely easy to roll off. At the same time, the existence of the air cushion increases the heat transfer resistance, making the liquid droplets on the superhydrophobic surface not easy to freeze at low temperatures. For superhydrophobic surfaces, constructing microstructures and applying low surface energy modifiers are common strategies.

[0004] Excellent superhydrophobic performance requires the support of a stable microstructure. Although common methods such as spraying and chemical etching are simple, the obtained structure has low quality and poor stability; while the preparation of high-quality microstructure arrays often uses processes such as photolithography and ion etching, which are expensive and not suitable for large-scale industrial production.

[0005] Currently, the superhydrophobic modification of most surfaces relies on the modification of low surface energy substances. However, low surface energy hydrophobic agents often gradually lose or decompose during the use on the surface, resulting in the weakening of the superhydrophobic performance of the surface with the use time. In addition, the use of organic fluorides (perfluorinated and polyfluorinated substances) to achieve strong superhydrophobic performance is very common. Organic fluorides pose great safety hazards to the environment and human health, and the demand for "defluorination" in current production and manufacturing is also receiving more and more attention. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the present invention provides a fluorine-free superhydrophobic anti-icing surface with a micro-nano composite structure and a preparation method thereof.

[0007] To achieve the above objectives, the present invention is realized through the following technical solutions:

[0008] The present invention discloses a preparation method of a fluorine-free superhydrophobic anti-icing surface with a micro-nano composite structure. Picosecond laser is used to perform horizontal and vertical cross-scanning processing on the surface of a substrate, inducing an array of micro-nano composite structures on the surface of the substrate, and annealing treatment is carried out. After natural cooling, a fluorine-free superhydrophobic anti-icing surface is obtained.

[0009] Preferably, the substrate is any one of stainless steel, titanium and its alloys, aluminum and its alloys, and zirconia ceramics.

[0010] Preferably, during the picosecond laser processing, the scanning spacing is 10-50 μm, the scanning speed is 5-100 mm / s, the laser power is 5-20 W, the laser frequency is 10-100 kHz, and the scanning times are 1-5 times.

[0011] Preferably, the annealing temperature is 90-150 °C and the annealing time is 0.5-2 h.

[0012] Correspondingly, a fluorine-free superhydrophobic anti-icing surface with a micro-nano composite structure prepared by the above-mentioned preparation method.

[0013] The present invention has the following beneficial effects:

[0014] 1. By regulating the parameters of laser processing, the present invention induces and constructs a hierarchical structure array with periodic micro-nano composites on different substrates, and realizes superhydrophobic performance without additional application of hydrophobic modifiers; the high-quality micro-nano structure can support the surface to achieve a water contact angle of more than 160°, and can almost completely inhibit the freezing of water droplets in a low-temperature environment of -5 °C.

[0015] 2. The preparation process of the fluorine-free superhydrophobic surface of the present invention is simple, has strong stability, is green and environmentally friendly, can adapt to a variety of substrates and complex curved surfaces, and at the same time has excellent superhydrophobic and anti-icing performance, and is suitable for large-scale preparation and application. Description of the Drawings

[0016] Figure 1 It is a scanning electron microscope image of the sample surface in Example 1 at a magnification of 2k;

[0017] Figure 2 It is a scanning electron microscope image of the sample surface in Example 1 at a magnification of 30k;

[0018] Figure 3 It is a 3D optical profilometry image of the sample surface in Example 1;

[0019] Figure 4 It is an image for measuring the contact angle of water droplets on the sample surface in Example 2;

[0020] Figure 5 It is an effect picture of the mirror phenomenon when the sample surface in Example 2 is immersed in water;

[0021] Figure 6 Photographing during the freezing experiment of the sample in Example 2 under the conditions of -5°C and 70% relative humidity. Detailed implementation mode

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0023] If not specifically specified, the technical means used in the implementation examples are conventional means well known to those skilled in the art.

[0024] The present invention discloses a preparation method of a fluorine-free superhydrophobic anti-icing surface with a micro-nano composite structure, including the following steps:

[0025] (1) Pretreatment: The substrate is successively cleaned with anhydrous ethanol and distilled water under ultrasonic conditions, and then taken out and dried; the substrate is any one of stainless steel, titanium and its alloys, aluminum and its alloys, and zirconia ceramics.

[0026] (2) Laser processing: Use picosecond laser to perform horizontal and vertical cross-scanning processing on the surface of the pretreated substrate. By setting the laser processing process parameters, an array of micro-nano composite structures is induced on the substrate surface; the laser processing process parameters are: the scanning pitch is 10-50 μm, the scanning speed is 5-100 mm / s, the laser power is 5-20 W, the laser frequency is 10-100 kHz, and the scanning times are 1-5 times.

[0027] (3) Hydrophobic treatment: The processed sample is successively rinsed with anhydrous ethanol and distilled water, and then placed in an oven for annealing treatment. After natural cooling, a fluorine-free superhydrophobic anti-icing surface is obtained. The annealing temperature is 90-150°C, and the annealing time is 0.5-2 h.

[0028] The laser processing of the present invention produces a hierarchical structure of micron-nano composite. The contact angle of the superhydrophobic surface exceeds 160° in the contact angle test, and in a low-temperature environment of -5°C, the droplet freezing behavior on the surface can be almost completely inhibited.

[0029] Next, the present invention will be further elaborated in conjunction with specific embodiments.

[0030] Example 1

[0031] Using a TA1 titanium sheet as the substrate, including the following steps:

[0032] (1) Pretreatment: The substrate was successively cleaned with absolute ethanol and distilled water under ultrasonic conditions, taken out and dried.

[0033] (2) Laser processing: The scanning pitch of the laser was set at 30 μm, the scanning speed was 10 mm / s, the laser power was 12 W, the laser frequency was 100 kHz, and the number of scanning times was 1 time.

[0034] (3) Hydrophobic treatment: The processed sample was successively rinsed with absolute ethanol and distilled water, and then placed in an oven for annealing treatment. The annealing temperature was 100 °C and the annealing time was 1 hour. After natural cooling, a fluorine-free superhydrophobic anti-icing surface was prepared. The static water contact angle of the surface was measured to be 166°. The scanning electron microscope images at different magnifications are shown in Figure 1 、 Figure 2 shown, and the 3D optical profilometry images are shown in Figure 3 shown. The results show that after laser ablation processing, periodic micro-scale groove arrays are generated on the sample surface, and at the same time, nano-scale spherical flower structures are covered on the surface of the structural arrays. The rich hierarchical structures greatly enhance the superhydrophobic performance and anti-icing ability of the surface.

[0035] Example 2

[0036] Using SUS 304 stainless steel as the substrate, the following steps are included:

[0037] (1) Pretreatment: The substrate was successively cleaned with absolute ethanol and distilled water under ultrasonic conditions, taken out and dried.

[0038] (2) Laser processing: The scanning pitch of the laser was set at 30 μm, the scanning speed was 10 mm / s, the laser power was 16 W, the laser frequency was 100 kHz, and the number of scanning times was 2 times.

[0039] (3) Hydrophobic treatment: The processed sample was successively rinsed with absolute ethanol and distilled water, and then placed in an oven for annealing treatment. The annealing temperature was 100 °C and the annealing time was 1 hour. After natural cooling, a fluorine-free superhydrophobic anti-icing surface was prepared. The static water contact angle of the surface was measured to be 165 ± 1°. The results are shown in Figures 4 - 6 shown. The results show that the sample surface exhibits excellent superhydrophobic performance after annealing treatment. After it is immersed in water, the air stored in the micro-nano structures on the sample surface causes total internal reflection of light, thus producing a mirror phenomenon ( Figure 5 ). Under the conditions of -5 °C and relative humidity of 70%, the static droplets placed on the sample surface did not freeze within a time of more than 60 min ( Figure 6 ), showing excellent anti-icing performance.

[0040] Comparative Example 1

[0041] Using SUS 304 stainless steel as the substrate, it includes the following steps:

[0042] (1) Pretreatment: Clean the substrate successively with absolute ethanol and distilled water under ultrasonic condition, take it out and dry it.

[0043] (2) Laser processing: Set the scanning pitch of the laser to 30 μm, the scanning speed to 10 mm / s, the laser power to 10 W, the laser frequency to 100 kHz, and the number of scanning times to 4 times.

[0044] (3) Hydrophobic treatment: Rinse the processed sample successively with absolute ethanol and distilled water, then place it in an oven for annealing treatment. The annealing temperature is 100 °C and the annealing time is 1 hour. After natural cooling, a fluorine-free superhydrophobic anti-icing surface is prepared. The static water contact angle of the surface is measured to be 150 ± 1°.

[0045] Compared with Example 1, although microstructures were generated by laser processing in Comparative Example 1, no nanostructures appeared, and the key micro-nano hierarchical structure could not be successfully constructed, resulting in the easy degradation of the droplet wetting state on the sample surface from the Cassie state to the Wenzel state, leading to a significant decrease in its anti-icing performance.

[0046] According to Examples 1-2 and Comparative Example 1, for the preparation of superhydrophobic anti-icing surfaces, the influencing factors include the substrate material, laser power, laser frequency, and scanning speed. Therefore, according to Examples 1-2 and Comparative Example 1, when the same substrate is applied with different process parameters such as laser power, there are cases where fluorine-free superhydrophobic anti-icing surfaces cannot be successfully prepared.

[0047] The above-described embodiments are only descriptions of the preferred modes of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A preparation method of a fluorine-free superhydrophobic anti-icing surface with a micro-nano composite structure, characterized in that: Use picosecond laser to perform horizontal and vertical cross-scanning processing on the substrate surface, induce the generation of a micro-nano composite structure array on the substrate surface, and perform annealing treatment. After natural cooling, a fluorine-free superhydrophobic anti-icing surface is obtained.

2. The preparation method according to claim 1, characterized in that: The substrate is any one of stainless steel, titanium and its alloys, aluminum and its alloys, and zirconia ceramics.

3. The preparation method according to claim 1, wherein: During the picosecond laser processing, the scanning spacing is 10-50 μm, the scanning speed is 5-100 mm / s, the laser power is 5-20 W, the laser frequency is 10-100 kHz, and the scanning times are 1-5 times.

4. The preparation method according to claim 1, wherein: The annealing temperature is 90-150 °C, and the annealing time is 0.5-2 h.

5. A fluorine-free superhydrophobic anti-icing surface with a micro-nano composite structure prepared by the preparation method described in claims 1 to 4.

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