Cross-scale fish scale array structural material and preparation method thereof

Abstract

The present invention discloses a cross-scale fish scale array structural material and a preparation method thereof, belonging to the field of hydrophobic materials. The surface of the material is prepared with several rows of cross-scale fish scale linear arrays and the surface is coated with a hydrophobic film, each row of linear arrays is composed of several fish scale drag reduction units arranged in sequence, and the adjacent linear arrays are staggered by half a unit period; each drag reduction unit is etched with several strip microchannels on a mesoscopic scale, and a fish scale-shaped arc flow channel running through all microchannels is etched in the middle. The strip microchannel of the present invention can significantly reduce the resistance of the material surface, reduce the pollution caused by biological aggregation, and play an anti-fouling effect; the fish scale-shaped arc flow channel can reduce the laminar-turbulent conversion consumption, further reduce the resistance, thereby providing better drag reduction and anti-fouling performance. At the same time, the preparation method of the present invention combines femtosecond laser etching and super hydrophobic gel film coating technology, and can quickly and large-area process cross-scale fish scale array structural materials that meet the requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrophobic materials, and in particular relates to a marine cross-scale imitation fish scale array structural material and a preparation method thereof. Background Art

[0002] According to the requirements of energy conservation and emission reduction in the United Nations Framework Convention on Climate Change, countries around the world need to carry out technical research and development of ship drag reduction and antifouling materials. my country needs to develop from a large shipbuilding country to a strong shipbuilding country, and the technology of drag reduction and antifouling ship materials urgently needs to be upgraded. However, to achieve the cross-scale bionic structure integrated design, shape and property synergistic function regulation and processing of drag reduction and antifouling structural functional materials under complex hydrodynamic conditions, there are still many complex scientific and technological problems.

[0003] There are two main types of ship surface antifouling material technologies: antifouling coatings and artificial surface microstructure antifouling. Antifouling coatings mainly include toxic coatings, low surface energy coatings, and natural bionic coatings. The University of Electronic Science and Technology of China has studied self-powered antifouling surface polymer coating technology, which can reduce the attachment and pollution of various microorganisms. Artificial surface microstructure antifouling technology achieves antifouling function by directly manufacturing specific microstructures on the surface of the material, and has specific biological-structural correspondence, that is, a single microstructure is usually only effective for one or several organisms. In short, the above studies are generally laboratory verifications of single drag reduction or antifouling functions, and there are no reports on bionic materials with drag reduction and antifouling functions for multi-speed engineering applications.

[0004] Shark skin has a special cross-scale micro-nano structure that can have both excellent drag reduction properties and anti-biological adhesion. Therefore, the combination of cross-scale composite bionic micro-nano structure and surface bionic gel film is the main development direction of drag reduction and anti-fouling in the future. The mechanism exploration and research of drag reduction and anti-fouling multifunctional bionic structural materials, the breakthrough of integrated design and manufacturing process are the key to its performance improvement and practical application. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a cross-scale fish scale array structural material with drag reduction and anti-fouling functions and a preparation method thereof, so as to further reduce shipping resistance and reduce energy consumption.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A cross-scale fish scale array structural material, characterized in that a plurality of cross-scale fish scale linear arrays are prepared on the surface of the material and the surface is coated with a hydrophobic film, each column of the cross-scale fish scale linear arrays is composed of a plurality of fish scale drag reduction units arranged in sequence, and the cross-scale fish scale linear arrays in two adjacent columns are staggered by half a unit period; the material has both drag reduction and anti-fouling properties.

[0008] The fish scale drag reduction unit is etched with a plurality of strip-shaped micro-channels on a mesoscopic scale along the linear array direction.

[0009] The fish scale drag reduction unit has a fish scale arc flow channel etched in the middle that runs through all the strip-shaped micro-channels, and the center line of the fish scale arc flow channel is perpendicular to the linear array direction of the fish scale drag reduction unit.

[0010] Furthermore, the length of the fish scale drag reduction unit along the linear array direction is 24mm-26mm, and the length perpendicular to the linear array direction is 50mm-54mm.

[0011] Furthermore, the hydrophobic film coated on the surface of the array is evenly coated by spraying, and the coating used is a trichlorosilane-based organic coating.

[0012] Furthermore, the depth of the strip-shaped microchannel is in the range of 0.08 mm to 0.12 mm, the width is in the range of 0.08 mm to 0.12 mm, and the center distance between adjacent strip-shaped microchannels is in the range of 0.18 mm to 0.22 mm.

[0013] Furthermore, the depth of the fish-scale arcuate flow channel ranges from 0.45 mm to 0.55 mm, and the width ranges from 0.18 mm to 0.22 mm.

[0014] Furthermore, the interval between two adjacent rows of fish scale micro-nano linear arrays is less than 0.8 mm.

[0015] Based on the above-mentioned cross-scale fish scale array structural material, the present invention also provides a preparation method thereof, comprising the following steps:

[0016] Step 1-1. Polishing the surface of the substrate;

[0017] The substrate surface is polished with sandpaper from coarse to fine, and then polished with a polishing cloth; after polishing, it is cleaned with anhydrous ethanol to remove impurities, and finally blown dry with dry nitrogen. Before laser processing, the substrate surface is polished to ensure the consistency of the initial roughness.

[0018] Step 1-2. Cleaning the substrate surface;

[0019] The substrate was ultrasonically cleaned with toluene, ketone and anhydrous ethanol in sequence, and then dried with dry nitrogen to remove organic impurities on the surface (oil stains, etc.); the substrate was ultrasonically cleaned with deionized water, and finally dried with dry nitrogen and placed on clean filter paper for later use.

[0020] Step 1-3. Femtosecond laser ablation of the sample surface;

[0021] The substrate surface is etched by femtosecond pulse laser to obtain a substrate material with a fish scale micro-nano array surface structure.

[0022] Step 1-4. Cleaning the substrate;

[0023] The substrate was ultrasonically cleaned with anhydrous ethanol, then dried with dry nitrogen and placed on a clean filter paper for later use.

[0024] Step 2-1. Apply primer;

[0025] Allyl trimethoxy silane is used as a coating primer, and the primer is evenly sprayed on the surface of the fish scale micro-nano array structure through an air pressure sprayer, and then blown dry with dry nitrogen.

[0026] Step 2-2. Coating polysiloxane to form a cross-linked network;

[0027] Use compressed air spraying to atomize the polysiloxane coating and spray it on the primer surface to form a strong cross-linking network with the allyl trimethoxy silane primer, and then dry it naturally in a cool and ventilated place until it is completely cured;

[0028] Step 2-3. Infiltrating with an organic solution;

[0029] The sample with completely cured surface coating is placed in an organic solution and allowed to stand for 1 to 2 hours to allow it to be completely soaked, thereby forming a super-hydrophobic antifouling gel film and completing the preparation of a cross-scale fish scale array structural material.

[0030] This process combines femtosecond laser etching technology and bionic superhydrophobic gel film coating technology, which can quickly and large-area process cross-scale fish scale array structural materials that meet the requirements.

[0031] The beneficial effects of the present invention are:

[0032] 1. The microchannel structure on the surface of the fish scale drag reduction unit ensures that air is captured in the surface microstructure, forming an air gap between the material and the liquid interface and generating effective slip without providing a continuous gas interface. The resistance applied to the material can be significantly reduced. The super-hydrophobic properties formed by the microchannel design can also reduce biological aggregation and the pollution caused by biological aggregation, playing an anti-fouling role.

[0033] 2. The design of the fish-scale arc flow channel imitates the general shape of fish scales, reduces the laminar-turbulent conversion consumption on the material surface, can provide good flow guidance, and further reduce the resistance applied to the material, thereby providing better drag reduction and anti-fouling performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1Schematic diagram of a super-hydrophobic cross-scale fish scale array structural material; wherein (a) is a schematic diagram of a multi-unit structure, and (b) is a schematic diagram of a double-unit structure;

[0035] Figure 2 This is a process flow chart for the processing of super-hydrophobic cross-scale fish scale array structural materials;

[0036] Figure 3 This is a simulation effect diagram of an embodiment of the present invention under fluid conditions;

[0037] Figure 4 The figure is a comparison of the fluid simulation effects with and without the super-hydrophobic cross-scale fish-scale array structure material; (a) is the material with the fish-scale array structure, and (b) is the material without the fish-scale array structure.

[0038] Explanation of the accompanying figures: 1. Strip-shaped microchannel, 2. Fish-scale-shaped arc channel. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and some points of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application usually described and represented in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of protection of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. The present invention is further described below in conjunction with the drawings.

[0040] The preparation method of the cross-scale fish scale array structure material of this embodiment is as follows:

[0041] Step 1. preparing a sample with a micro-nano array surface;

[0042] Step 1-1. Polishing the composite material sample;

[0043] 304L low-carbon stainless steel, a common steel material for ships, was used as the base material for femtosecond laser processing. The composite material samples were polished with sandpaper from coarse to fine, and the sandpaper used was 180#, 400#, 800#, and 2000# in order, and then polished with a polishing cloth. After polishing, the sample was placed in a container filled with anhydrous ethanol for ultrasonic cleaning for 10 minutes to remove surface impurities, and finally dried with dry nitrogen. Before laser processing, the initial roughness of the composite material sample was ensured to be consistent through polishing.

[0044] Step 1-2. Cleaning the composite material sample;

[0045] The polished stainless steel material was placed in containers containing toluene, ketone, and anhydrous ethanol in turn, and ultrasonically cleaned for 20 minutes, and then blown dry with dry nitrogen to remove organic impurities such as oil on the surface; the stainless steel material was placed in a container containing deionized water, and ultrasonically cleaned for 15 minutes, and then blown dry with dry nitrogen; finally, the material was placed on clean filter paper to dry for later use.

[0046] Step 1-3. Femtosecond laser ablation of the composite sample surface;

[0047] The laser setting parameters of this embodiment are: laser scanning speed is 0.5mm / s, scanning interval is 100μm, laser pulse polarization state is linear polarization state, laser pulse energy is 300μJ, and the maximum processing range is 20×40mm 2 By etching the microstructure of the material surface with femtosecond laser pulses, a material sample with a cross-scale fish-scale array structure that meets the wetting properties is obtained.

[0048] Step 1-4. Clean the sample;

[0049] The composite material sample after femtosecond laser etching was cleaned, placed in a container containing anhydrous ethanol for 20 minutes of ultrasonic cleaning, and finally dried with dry nitrogen and placed on clean filter paper to dry for use.

[0050] Step 2. Preparation of super hydrophobic antifouling gel film surface material

[0051] Step 2-1. Apply primer;

[0052] Allyl trimethoxy silane was used as a coating primer, which was evenly sprayed on the surface of the sample by a pressure sprayer and then dried with dry nitrogen.

[0053] Step 2-2. Coating polysiloxane to form a cross-linked network;

[0054] Use compressed air spraying to atomize the polysiloxane coating and spray it on the primer surface to form a strong cross-linking network with the allyl trimethoxy silane primer, and then let it dry naturally in a cool and ventilated place for 2 hours until it is completely cured;

[0055] Step 2-3. Infiltrating with an organic solution;

[0056] Take the sample with completely cured surface coating and put it into N-octadecyl trichlorosilane solution and let it stand for 2 hours to make it completely wetted to form a molecular scale super hydrophobic antifouling gel film. Figure 1-3The cross-scale fish scale array structural material shown. The size of a single fish scale drag reduction unit is 52mm*25mm; the interval between fish scale arrays is 0.5mm; the strip microchannels etched on the fish scale drag reduction unit at the mesoscopic scale are 0.1mm deep*0.1mm wide, with a center distance of 0.2mm; the fish scale arc channel is 0.5mm deep*0.2mm wide.

[0057] In order to test the drag reduction performance of the prepared material samples under flow conditions, Comsol was used to build a basic fluid environment for simulation testing. The fluid used was an incompressible single-phase Newtonian liquid flow. The specific parameters included a dynamic viscosity coefficient of 1.01×10^(-3)Pa·s and a density of 1×10^3kg / m 3 , the ambient temperature is 293.15K. This embodiment simulates and displays the fluid flow in a 2mm space near the surface of the super-hydrophobic fish scale micro-nano array structure. When the fluid flow velocity is set to 2m / s, the calculated Reynolds number Re is about 26000, which belongs to the turbulent flow condition.

[0058] Under the above implementation conditions, the fluid Figure 3 The +x direction flows through the material surface, and the friction and shear force caused by the gravity of the fluid generate fluid resistance. The specific flow conditions are as follows: Figure 3 as well as Figure 4 As shown, the coordinate x=4mm is selected (the coordinate axis is as Figure 3 As shown in the figure, the velocity field cross sections at y=26mm and z=5.1mm show that there is an obvious velocity gradient within 0.2mm on the surface of the superhydrophobic fish scale array drag reduction and antifouling functional material, while it is consistent with the average velocity at a farther distance. In the lateral dimension, it is basically uniform, indicating that the microchannel plays a very good role in guiding the flow. Under turbulent conditions, it can also maintain a velocity distribution close to laminar flow. At the same time, Figure 3 As shown in the xoy plane, the velocity distribution along the microchannel direction can be clearly observed. At the same time, the velocity near the arc channel is significantly lower than that in other areas, which correspondingly reduces the local shear stress in this area.

[0059] In order to better quantify the drag reduction performance of the cross-scale fish scale array structural material, the flow conditions with and without the fish scale drag reduction and anti-fouling structure were simulated and calculated by Comsol, and the corresponding friction resistance was calculated by Formula 1, where spf.rho is the fluid density, *spf.u_tau is the flow velocity, spf.uPlus is the tangential dimensionless velocity, spf.nxmesh, spf.nymesh, spf.nzmesh are the normal vectors in each direction, uvw is the flow velocity in the xyz direction, and finally the integral is performed over the entire resistance area to obtain the corresponding friction resistance.

[0060] spf.rho*spf.u_tau*((v-spf.nymesh*(u*spf.nxmesh+v*spf.nymesh+w*spf.nzmesh))) / s

[0061] pf.uPlus(1)

[0062] Finally, the friction resistance of the drag reduction unit structure with fish scales is 2.5031*10^-4N, and the friction resistance of the drag reduction unit structure without fish scales is 2.6176*10^-4N. The surface drag reduction rate is defined as shown in Formula 2, where Fs is the friction resistance of the drag reduction unit structure without fish scales, and Fc is the friction resistance of the drag reduction unit structure with fish scales. The calculated drag reduction performance reaches 4.37%.

[0063]

[0064] The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other alternative features that are equivalent or have similar purposes; all disclosed features, or all steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way; any non-essential additions and substitutions made by technicians in this field based on the technical features of the technical solution of the present invention belong to the protection scope of the present invention.

Claims

1. A cross-scale fish scale array structural material, characterized in that: The surface of the material is prepared with several rows of cross-scale fish scale linear arrays and coated with a hydrophobic film. Each row of the cross-scale fish scale linear arrays is composed of several fish scale drag reduction units arranged in sequence, and the cross-scale fish scale linear arrays in two adjacent rows are staggered by half a unit period. The material has both drag reduction and anti-fouling properties. The fish scale drag reduction unit is etched with a plurality of strip-shaped microchannels on a mesoscopic scale along the linear array direction; The fish scale drag reduction unit has a fish scale arc flow channel etched in the middle that runs through all the strip-shaped micro-channels, and the center line of the fish scale arc flow channel is perpendicular to the linear array direction of the fish scale drag reduction unit.

2. The cross-scale fish scale array structural material according to claim 1, characterized in that: The interval between two adjacent rows of fish scale micro-nano linear arrays is less than 0.8 mm.

3. The cross-scale fish scale array structural material according to claim 2, characterized in that: The length of the fish scale drag reduction unit along the linear array direction is 24mm-26mm, and the length perpendicular to the linear array direction is 50mm-54mm.

4. The cross-scale fish scale array structural material according to claim 3, characterized in that: The depth of the strip-shaped microchannel is in the range of 0.08 mm to 0.12 mm, the width is in the range of 0.08 mm to 0.12 mm, and the center distance between adjacent strip-shaped microchannels is in the range of 0.18 mm to 0.22 mm.

5. The cross-scale fish scale array structural material according to claim 4, characterized in that: The depth of the fish-scale arc flow channel ranges from 0.45 mm to 0.55 mm, and the width ranges from 0.18 mm to 0.22 mm.

6. A cross-scale fish scale array structural material according to any one of claims 2 to 5, characterized in that: The hydrophobic film coated on the surface of the array is evenly coated by spraying, and the coating used is trichlorosilane organic coating.

7. A cross-scale fish scale array structural material according to any one of claims 1 to 5, characterized in that: The preparation method of the material comprises the following steps: Step 1-1. Polishing the surface of the substrate; Step 1-2. Cleaning the substrate surface; Step 1-3. Femtosecond laser ablation of the sample surface to obtain a substrate material having a fish scale micro-nano array surface structure; Step 1-4. Cleaning the substrate; Step 2-1. Apply primer; Allyl trimethoxy silane is used as a coating primer, and the primer is evenly sprayed on the surface of the fish scale micro-nano array structure through an air pressure sprayer, and then dried for use; Step 2-2. Coating polysiloxane to form a cross-linked network; The polysiloxane coating is sprayed on the primer surface by atomization using compressed air spraying to form a strong cross-linking network with the allyl trimethoxy silane primer, and then dried until fully cured; Step 2-3. Infiltrating with an organic solution; A sample with completely cured surface coating is placed in an organic solution and allowed to stand for 1 to 2 hours to form a super-hydrophobic antifouling gel film, thereby completing the preparation of a cross-scale fish scale array structural material.

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