CN109611419B - Metal-based underwater bionic gas film drag reduction surface and preparation method and application thereof - Google Patents
Metal-based underwater bionic gas film drag reduction surface and preparation method and application thereof Download PDFInfo
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- CN109611419B CN109611419B CN201811513829.6A CN201811513829A CN109611419B CN 109611419 B CN109611419 B CN 109611419B CN 201811513829 A CN201811513829 A CN 201811513829A CN 109611419 B CN109611419 B CN 109611419B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15D—FLUID DYNAMICS, i.e. METHODS OR MEANS FOR INFLUENCING THE FLOW OF GASES OR LIQUIDS
- F15D1/00—Influencing flow of fluids
- F15D1/002—Influencing flow of fluids by influencing the boundary layer
- F15D1/0025—Influencing flow of fluids by influencing the boundary layer using passive means, i.e. without external energy supply
- F15D1/003—Influencing flow of fluids by influencing the boundary layer using passive means, i.e. without external energy supply comprising surface features, e.g. indentations or protrusions
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
- B63B1/32—Other means for varying the inherent hydrodynamic characteristics of hulls
- B63B1/34—Other means for varying the inherent hydrodynamic characteristics of hulls by reducing surface friction
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15D—FLUID DYNAMICS, i.e. METHODS OR MEANS FOR INFLUENCING THE FLOW OF GASES OR LIQUIDS
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Abstract
The invention discloses a metal-based underwater bionic gas film drag reduction surface and a preparation method and application thereof. The underwater bionic gas film drag reduction surface of the metal matrix comprises a metal matrix, a pit-shaped microstructure arranged on the surface of the metal matrix and a zinc oxide nanorod array arranged on the surface of the pit-shaped microstructure. The invention is inspired by the gas adsorption functional surface of the water spider, firstly a laser etching technology is adopted to process a pit-shaped micron-scale array structure on the surface of a metal base, a deposition process is adopted to deposit a zinc oxide seed crystal layer on the surface of a microstructure, finally a hydrothermal method is adopted to grow a zinc oxide nano-rod array structure on the surface of the microstructure, after heat treatment, the microstructure surface similar to a bristle-shaped structure is obtained, the bionic surface can absorb air in water to form a stable gas film, and the resistance reduction effect is realized.
Description
Technical Field
The invention relates to the technical field of bionic drag reduction, in particular to a metal-based underwater bionic air film drag reduction surface and a preparation method and application thereof.
Background
The 21 st century is the century of oceans, and the development of oceanic economy and the acceleration of ocean construction are definitely one of the most important ocean development strategies in China. And marine navigation bodies such as aircraft carriers, underwater vehicles (such as submarines, torpedoes and the like), surface ships and the like play a very important role in marine economic construction and marine defense development. When these sailing bodies are sailing in the sea, they generate viscous friction resistance with the sea, this resistance is about 1000 times that of the air, and as the speed increases gradually, the resistance of the water increases in the order of its square, in the conventional case, the thrust needs to increase 8 times to double the sailing speed of the sailing bodies. The method not only reduces the navigation speed and the combat performance of the navigation body, but also brings about the serious problem of energy waste. In addition, because the underwater vehicle with limited size limits the scale of the thrust device, the speed of the underwater vehicle cannot be faster than that of the aerial vehicle under the conventional conditions, so that the speed of the underwater vehicle is much slower than that of the aerial vehicle during underwater navigation, and therefore, the realization of the underwater high-speed vehicle urgently needs subversive major technical breakthrough and innovative research, and how to effectively reduce the flowing friction resistance on the surface of the underwater vehicle plays an important role in the whole underwater drag reduction technology, and the underwater vehicle becomes an important means for improving the navigation speed and the energy utilization rate.
The research on the resistance reduction technology has undergone the development of the resistance reduction theory from how to reduce the surface roughness to the near-wall turbulent boundary layer, so that the resistance reduction technologies such as bionic resistance reduction, hydrophobic/super-hydrophobic resistance reduction and the like have good application prospects. Among them, the bionic drag reduction technology simulating the scale microstructure, secreted mucus and elastic epidermis of the body surface of fishes (such as sharks and dolphins) in nature has become one of the drag reduction methods with practical prospect. For example, the invention patent with the application number of '201410353097.4' and the invention name of 'a large-area copying method of bionic sharkskin drag reduction micro-grooves' simplifies the body surface microstructure of real sharkskin and adopts the UV-LIGA technology and the rolling process to prepare the bionic sharkskin polymer drag reduction surface. The high-fidelity shark-imitating drag reduction structure comprises a shark-imitating cortex, the upper surface of the shark-imitating cortex is scaly, at least two grooves are dug in the lower surface of the shark-imitating cortex, the at least two grooves are communicated with each other, through holes communicating the upper surface and the lower surface are formed in the grooves, and the high-fidelity shark-imitating drag reduction structure further comprises a slow-release electro-hydraulic control system which forms a drag reduction structure with an efficient coupling drag reduction effect under the combined action of the slow-release electro-hydraulic control system. The invention discloses a bionic sharkskin surface with double resistance reducing functions, which is prepared by combining an elastic surface layer, a viscoelastic flexible bottom layer and a sharkskin, and has the application number of 201010532238.0 and the invention name of 'bionic resistance reducing film material based on sharkskin surface and matrix structure and a preparation method thereof'. The application number is '201710227922. X', the invention name is 'a puffer fish skin appearance-imitating underwater drag reduction surface and a manufacturing method thereof', the drag reduction surface comprises a substrate, hard drag reduction elements and a flexible covering layer, wherein a plurality of hard drag reduction elements are distributed on the substrate, the flexible covering layer is filled between the hard drag reduction elements, and the hard drag reduction elements are tightly attached to the bonding surfaces of the substrate and the hard drag reduction elements. However, in practical application, the resistance-reducing surface with the fish scale-like microstructure still has the defects of easy damage of the surface structure, unsuitability for high-speed motion state in water, poor resistance-reducing effect, narrow application range and the like.
The water spider (Argyronet aquatica) in the nature is a unique aquatic organism as the only spider species living in water in the world, can gather a large amount of air by utilizing the combination of the ripple groove microstructures distributed on the body surface, the setae and the fluff on the setae, and further forms a stable air film around the water spider, so that the body surface of the water spider is wrapped by a layer of air film under water, the frictional resistance of the water borne by the body surface of the water spider is reduced, the super-hydrophobic characteristic of the surface of the water spider is increased, and the water spider can freely and quickly move away in the water. Inspired by the gas-attached functional surface of the water-borne spider, the bionic gas film micro-nano characteristic structure surface is established, and the underwater drag reduction effect is realized.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide a metal-based underwater bionic air film resistance-reducing surface, and a preparation method and application thereof, and aims to solve the problems that the existing resistance-reducing surface is easy to damage in structure, is not suitable for a high-speed motion state in water, has poor resistance-reducing effect, and is narrow in application range.
The technical scheme of the invention is as follows:
the metal-based underwater bionic gas film drag reduction surface comprises a metal substrate, a pit-shaped microstructure arranged on the surface of the metal substrate, and a zinc oxide nanorod array arranged on the surface of the pit-shaped microstructure.
The metal-based underwater bionic gas film drag reduction surface is characterized in that the metal matrix is selected from one of a pure aluminum matrix, an aluminum alloy matrix, a red copper matrix and a stainless steel matrix.
The metal-based underwater bionic gas film drag reduction surface is characterized in that the pit-shaped microstructure is selected from one of a semicircular pit-shaped microstructure, a square pit-shaped microstructure and an inverted cone pit-shaped microstructure.
The metal-based underwater bionic gas film drag reduction surface is characterized in that the diameter of the semicircular pit-shaped microstructure is 35-75 um, the central distance between adjacent pits is 75-140 um, and the processing depth is 45-85 um;
or the side length of the square pit-shaped microstructure is 30-70 um, the central distance between adjacent pits is 70-140 um, and the processing depth is 45-85 um;
or the diameter of the inverted cone pit-shaped microstructure is 35um-75um, the center distance between adjacent pits is 75um-140um, and the processing depth is 45um-85 um.
The metal-based underwater bionic gas film drag reduction surface is characterized in that the cross section of the zinc oxide nano rod is in a regular hexagon, the side length of the regular hexagon is 150nm-400nm, the length of the zinc oxide nano rod is 2.5um-6.5um, and the distance between adjacent zinc oxide nano rods is 450nm-700 nm.
The metal-based underwater bionic gas film drag reduction surface is characterized in that the pit-shaped microstructure is a semicircular pit-shaped microstructure, the diameter of the semicircular pit-shaped microstructure is 65 micrometers, the central distance between adjacent pits is 95 micrometers, the processing depth is 75 micrometers, the cross section of the zinc oxide nano rod is in a regular hexagon shape, the side length of the regular hexagon is 300nm, the length of the zinc oxide nano rod is 5.5 micrometers, and the distance between adjacent zinc oxide nano rods is 550 nm;
or the pit-shaped microstructure is a square pit-shaped microstructure, the side length of the square pit-shaped microstructure is 55 micrometers, the central distance between adjacent pits is 100 micrometers, the machining depth is 65 micrometers, the cross section of the zinc oxide nanorod is in the shape of a regular hexagon, the side length of the regular hexagon is 350nm, the length of the zinc oxide nanorod is 5 micrometers, and the distance between adjacent zinc oxide nanorods is 650 nm;
or, pit form microstructure is back taper pit form microstructure, the diameter of back taper pit form microstructure is 75um, and the central distance between the adjacent pit is 115um, and the depth of processing is 85um, zinc oxide nano-rod's transversal is regular hexagon, regular hexagon's length of side is 400nm, zinc oxide nano-rod's length is 6.5um, and the distance between the adjacent zinc oxide nano-rod is 650 nm.
The invention relates to a preparation method of a metal-based underwater bionic gas film drag reduction surface, which comprises the following steps:
1) the surface pretreatment process of the metal matrix comprises the following steps: polishing the surface of the metal matrix by using abrasive paper, cleaning the polished surface of the metal matrix, and drying for later use;
2) preparing the surface in the step 1) into a metal base surface with a pit-shaped microstructure by adopting a laser etching processing technology;
3) depositing a zinc oxide seed crystal layer on the surface of the step 2) by adopting a deposition process;
4) growing a zinc oxide nanorod array structure on the surface of the step 3) by adopting a hydrothermal method;
5) annealing the metal matrix obtained in the step 4) to obtain the underwater bionic gas film drag reduction surface of the metal matrix.
The metal-based underwater bionic gas film resistance-reducing meterThe preparation method of the surface, wherein the parameters of the laser etching process in the step 2) are as follows: the pulse width is (300 +/-100) fs, the frequency is 1.5kHz, and the energy density is 2.2J/cm2The scanning speed is 1.5mm/s, and the scanning interval is 70um-140 um.
The preparation method of the metal-based underwater bionic gas film drag reduction surface comprises the following steps of: placing a glass beaker containing formamide water solution with the mass concentration of 7-12% in a water bath kettle, controlling the temperature to be 55-95 ℃, then soaking the metal substrate deposited with the zinc oxide seed crystal layer in the step 3) in the glass beaker, enabling the surface of the zinc oxide seed crystal layer plated to be horizontally upward, vertically placing a metal zinc sheet into the glass beaker, keeping the distance between the metal zinc sheet and the metal substrate deposited with the zinc oxide seed crystal layer to be 3-10mm, and taking the metal zinc sheet as a reaction system, wherein the hydrothermal reaction time is 24-36 h.
The invention relates to application of a metal-based underwater bionic gas film drag reduction surface, wherein the metal-based underwater bionic gas film drag reduction surface is processed on the surface of an underwater sailing body or the bottom surface of a ship.
Has the advantages that: the drag reduction surface of the metal-based underwater bionic air film is similar to a microstructure surface embedded with a seta-shaped structure, and the bionic surface can adsorb air in water to form a stable air film so as to realize the drag reduction effect.
Drawings
FIG. 1 shows the static water contact angle of a metal-based underwater biomimetic air film drag reduction surface in air in an embodiment of the present invention.
FIG. 2 is a plot of drag reduction ratio of a metal-based underwater biomimetic air film drag-reducing surface and a common smooth surface in an embodiment of the present invention.
FIG. 3 is a graph of (a') and (a) time versus displacement during a drop in the x-axis direction at a specific drop height (H =3 cm) for a metal-based underwater biomimetic air film drag reducing surface and a common smooth surface in an embodiment of the present invention; (b') and (b) time versus velocity plots; (c') and (c) time vs. acceleration.
FIG. 4 is a graph of (a') and (a) time versus displacement during a fall in the y-axis direction at a specific fall height (H =3 cm) of a metal-based underwater biomimetic air film drag reducing surface in an embodiment of the present invention versus a conventional smooth surface; (b') and (b) time versus velocity plots; (c') and (c) time vs. acceleration.
Detailed Description
The invention provides a metal-based underwater bionic gas film drag reduction surface and a preparation method and application thereof, and the invention is further described in detail below in order to make the purpose, technical scheme and effect of the invention clearer and more clear. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The embodiment of the invention provides a metal-based underwater bionic gas film drag reduction surface which comprises a metal substrate, a pit-shaped microstructure arranged on the surface of the metal substrate and a zinc oxide nanorod array arranged on the surface of the pit-shaped microstructure.
In this embodiment, the underwater metal-based bionic air film drag reduction surface is a metal substrate surface with a micro-nano hierarchical structure, and specifically includes a pit-shaped microstructure disposed on the metal substrate surface and a zinc oxide nanorod array disposed on the pit-shaped microstructure surface. The metal-based underwater bionic air film drag reduction surface is provided with a microstructure surface embedded with a seta-shaped structure, and the bionic surface can adsorb air in water to form a layer of stable air film, so that the drag reduction effect is realized. The micro-nano double-layer hierarchical structure parameters of the bionic gas film drag reduction surface formed on the metal substrate can be adjusted, the frictional resistance borne by the surface can be effectively reduced, and the optimal drag reduction effect is achieved under the full-working-condition running state.
In a preferred embodiment, the metal substrate is selected from one of a pure aluminum substrate, an aluminum alloy substrate, a red copper substrate, a stainless steel substrate, and the like.
In a preferred embodiment, the dimple-like microstructure is selected from one of a semicircular dimple-like microstructure, a square dimple-like microstructure, and an inverted cone dimple-like microstructure.
Further in a preferred embodiment, the diameter of the semi-circular pit-like microstructure is 35um-75um, the center distance between adjacent pits is 75um-140um, and the processing depth is 45um-85 um. Under the action of the structural size parameter range, the super-hydrophobic characteristic of the bionic air film drag reduction surface in air and the super-hydrophilic bubble characteristic in an aqueous medium environment achieve the best effect.
Further in a preferred embodiment, the side length of the square pit-like microstructure is 30um-70um, the center distance between adjacent pits is 70um-140um, and the processing depth is 45um-85 um. Under the action of the structural size parameter range, the super-hydrophobic characteristic of the bionic air film drag reduction surface in air and the super-hydrophilic bubble characteristic in an aqueous medium environment achieve the best effect.
Further in a preferred embodiment, the diameter of the inverted cone-shaped pit-shaped microstructure is 35um to 75um, the center distance between adjacent pits is 75um to 140um, and the processing depth is 45um to 85 um. Under the action of the structural size parameter range, the super-hydrophobic characteristic of the bionic air film drag reduction surface in air and the super-hydrophilic bubble characteristic in an aqueous medium environment achieve the best effect.
In a preferred embodiment, the cross section of the zinc oxide nano rod is a regular hexagon, the side length of the regular hexagon is 150nm-400nm, the length of the zinc oxide nano rod is 2.5um-6.5um, and the distance between adjacent zinc oxide nano rods is 450nm-700 nm. Under the action of the structural size parameter range, the super-hydrophobic characteristic of the bionic air film drag reduction surface in air and the super-hydrophilic bubble characteristic in an aqueous medium environment achieve the best effect.
In an embodiment, pit-shaped microstructure is semi-circular pit-shaped microstructure, semi-circular pit-shaped microstructure's diameter is 65um, and the central distance between the adjacent pit is 75um-105um (like 75um, 85um, 95um, 105um, preferred 95 um), and the depth of processing is 75um, regular hexagon is personally submitted to zinc oxide nano-rod's transversal, regular hexagon's length of side is 300nm, zinc oxide nano-rod's length is 5.5um, and the distance between the adjacent zinc oxide nano-rod is 550 nm. Under the action of the size parameter range, the air film retention time of the bionic air film drag reduction surface in an aqueous medium environment can reach 10-40s, and the drag reduction effect is optimal.
In an embodiment, the pit-shaped microstructure is a square pit-shaped microstructure, the side length of the square pit-shaped microstructure is 55um, the central distance between adjacent pits is 80um-120um (such as 90um, 100um, 110um, 120um, preferably 100 um), the processing depth is 65um, the cross section of the zinc oxide nano rod is a regular hexagon, the side length of the regular hexagon is 350nm, the length of the zinc oxide nano rod is 5um, and the distance between adjacent zinc oxide nano rods is 650 nm. Under the action of the size parameter range, the air film retention time of the bionic air film drag reduction surface in an aqueous medium environment can reach 10-40s, and the drag reduction effect is optimal.
In an embodiment, pit-shaped microstructure is back taper pit-shaped microstructure, back taper pit-shaped microstructure's diameter is 75um, and the central distance between the adjacent pit is 95um-140um (as 95um, 105um, 115um, 125um, preferred 95 um), and the depth of processing is 85um, regular hexagon is personally submitted to zinc oxide nano-rod's transversal, regular hexagon's length of side is 400nm, zinc oxide nano-rod's length is 6.5um, and the distance between the adjacent zinc oxide nano-rod is 650 nm. Under the action of the size parameter range, the air film retention time of the bionic air film drag reduction surface in an aqueous medium environment can reach 10-40s, and the drag reduction effect is optimal.
The embodiment of the invention provides a preparation method of a metal-based underwater bionic air film drag reduction surface, which comprises the following steps:
1) and the surface pretreatment process of the metal matrix comprises the following steps: polishing the surface of the metal matrix by using abrasive paper, cleaning the polished surface of the metal matrix, and drying for later use;
2) preparing the surface in the step 1) into a metal base surface with a pit-shaped microstructure by adopting a laser etching processing technology;
3) depositing a zinc oxide seed crystal layer on the surface of the step 2) by adopting a deposition process;
4) growing a zinc oxide nanorod array structure on the surface of the step 3) by adopting a hydrothermal method;
5) annealing the metal matrix obtained in the step 4) to obtain the underwater bionic gas film drag reduction surface of the metal matrix.
The invention is inspired by the gas adsorption functional surface of the water spider, firstly a laser etching technology is adopted to process a pit-shaped micron-scale array structure on the surface of a metal base, a deposition process is adopted to deposit a zinc oxide seed crystal layer on the surface of a microstructure, finally a hydrothermal method is adopted to grow a zinc oxide nano-rod array structure on the surface of the microstructure, after heat treatment, the microstructure surface similar to a bristle-shaped structure is obtained, the bionic surface can absorb air in water to form a stable gas film, and the resistance reduction effect is realized.
In a preferred embodiment, the pretreatment process of the metal substrate surface in the step 1) specifically comprises the following steps: respectively polishing the surface of a metal matrix by using 400#, 800#, 1200#, 2000# abrasive paper to remove a surface oxide layer, then sequentially performing ultrasonic cleaning on the polished surface of the metal matrix by using deionized water, acetone, absolute ethyl alcohol and deionized water for 10-15min to remove residual impurities on the surface, and drying by using nitrogen for later use.
And 2) preparing the surface obtained in the step 1) into a metal-based surface with a semicircular, square or inverted cone-shaped pit-shaped microstructure by adopting a laser etching processing technology.
In a preferred embodiment, the parameters of the laser etching process in step 2) are: the pulse width is (300 +/-100) fs, the frequency is 1.5kHz, and the energy density is 2.2J/cm2The scanning speed is 1.5mm/s, and the scanning interval is 70um-140 um.
In a preferred embodiment, the deposition process in step 3) is selected from one of an atomic layer deposition process and a radio frequency magnetron sputtering process.
Further in a preferred embodiment, the reaction conditions of the deposition process of the original layer in step 3) are: selecting a precursor: dimethyl zinc and water; selection of deposition substrate temperature: room temperature-140 ℃; the thickness of the zinc oxide film of a single deposition cycle was: 0.55-0.65 nm; the number of deposition cycles was: 500 times and 1800 times.
Further in a preferred embodiment, the reaction conditions of the rf magnetron sputtering process in step 3) are as follows: ZnO ceramic (the purity is 99.99%) is selected as the sputtering target material; the temperature of the substrate is 80-100 ℃; the radio frequency power is 140W; the sputtering time is 30-60 min.
In a preferred embodiment, step 4) specifically comprises: placing a glass beaker containing formamide water solution with the mass concentration of 7-12% in a water bath kettle, controlling the temperature to be 55-95 ℃, then soaking the metal substrate (with the film plated surface facing upwards) deposited with the zinc oxide seed crystal layer in the step 3) in the glass beaker, vertically placing a metal zinc sheet in the glass beaker, keeping the distance between the metal zinc sheet and the metal substrate deposited with the zinc oxide seed crystal layer to be 3-10mm, and taking the metal zinc sheet as a reaction system, wherein the hydrothermal reaction time is 24-36 h.
In a preferred embodiment, the metal matrix sample obtained in the step 5) is sequentially cleaned by absolute ethyl alcohol and deionized water, dried by nitrogen, then placed into a muffle furnace for annealing treatment at the annealing temperature of 180-.
The embodiment of the invention also provides application of the metal-based underwater bionic gas film drag reduction surface, wherein the metal-based underwater bionic gas film drag reduction surface is processed on the surface of an underwater sailing body or the surface of the bottom of a ship. Compared with the common smooth metal-based surface, the average drag reduction rate of the bionic air film drag reduction surface is 15.64 percent, so that the bionic air film drag reduction surface can save energy and reduce drag of underwater navigation bodies and surface ships, improves endurance and shows good economic prospect.
The present invention will be described in detail below with reference to examples.
Example 1
The preparation method of the metal-based underwater bionic gas film drag reduction surface comprises the following steps:
(1) stainless steel is used as a base material (40 mm multiplied by 2 mm), and the surface pretreatment process of the stainless steel comprises the following steps: respectively polishing the surface of stainless steel by 400#, 800#, 1200#, 2000# abrasive paper to remove a surface oxide layer, then sequentially performing ultrasonic cleaning on the polished surface of the stainless steel by deionized water, acetone, absolute ethyl alcohol and deionized water for 15min to remove residual impurities on the surface, and drying by nitrogen for later use;
(2) preparing an inverted cone-shaped pit-shaped microstructure on the surface of the stainless steel in the step (1) by adopting a laser etching technology, wherein the parameters of the laser etching technology are as follows: the pulse width is 300fs, the frequency is 1.5kHz, and the energy density is 2.2J/cm2The scanning speed is 1.5mm/s, and the scanning interval is 95 um. The diameter of the processed inverted cone pit-shaped microstructure is 75um, the central distance between adjacent pits is 95um, and the processing depth is 85 um;
(3) depositing a zinc oxide seed crystal layer on the surface of the microstructure in the step (2) by adopting a radio frequency magnetron sputtering instrument, wherein the reaction condition of the radio frequency magnetron sputtering is as follows: ZnO ceramic (the purity is 99.99%) is selected as the sputtering target material; the substrate temperature is 85 ℃; the radio frequency power is 140W; the sputtering time is 45min, and the deposition thickness of the zinc oxide film is 750 nm;
(4) the process for preparing the zinc oxide nanorod array structure by adopting a hydrothermal method comprises the following steps: placing a glass beaker filled with formamide water solution with the mass concentration of 8.5% in a water bath kettle, controlling the temperature to be 75 ℃, then soaking the stainless steel substrate (with the film surface horizontally upward) plated with the zinc oxide film in the step (3) in the glass beaker, simultaneously vertically placing a metal zinc sheet into the glass beaker, keeping the distance of the metal zinc sheet and the stainless steel substrate plated with the zinc oxide film to be 3mm, taking the metal zinc sheet as a reaction system, and carrying out hydrothermal reaction for 24 hours, wherein the side length of a regular hexagon of the obtained zinc oxide nano rod is 400nm, the length of the regular hexagon is 6.5um, and the distance between adjacent nano rods is 650 nm;
(5) and (4) cleaning the stainless steel sample obtained in the step (4) with absolute ethyl alcohol and deionized water in sequence, drying the stainless steel sample with nitrogen, then putting the stainless steel sample into a muffle furnace for annealing treatment at 195 ℃ for 180min, and naturally drying and cooling to obtain the underwater bionic gas film drag reduction surface with the micro-nano structure.
The underwater bionic air film drag reduction surface prepared according to the implementation steps has a static surface contact angle of 153.64 degrees in air as shown in figure 1 (a). And under the aqueous medium environment, the bubble can adsorb on bionical appearance surface steadily, shows for super hydrophilic characteristic, and under the aqueous medium environment, this gas film can be 40s at the longest time that bionical appearance surface kept, and at this moment, bionical appearance surface can form the thin protection film of a layer of water, is equivalent to wrap up whole appearance piece with this gas film, has played lubricated effect to this bionical surface. Compared with a common smooth surface, the average drag reduction rate of the underwater bionic drag reduction surface is 15.64 percent, as shown in figure 2 (a). Fig. 3 is a graph of (a) and (a') time versus displacement during a fall in the x-axis direction at a specific fall height (H =3 cm) for a plain stainless steel smooth surface and the underwater biomimetic drag reducing surface; (b) and (b') a time versus velocity graph; (c) and (c') time versus acceleration. Fig. 4 is a graph of (a) and (a') time versus displacement during a fall in the y-axis direction at a specific fall height (H =3 cm) for a plain stainless steel smooth surface and an underwater biomimetic drag reducing surface; (b) and (b') a time versus velocity graph; (c) and (c') a time and acceleration curve chart, and has ideal drag reduction effect.
Example 2
The preparation method of the metal-based underwater bionic gas film drag reduction surface comprises the following steps:
(1) stainless steel is used as a base material (40 mm multiplied by 2 mm), and the surface pretreatment process of the stainless steel comprises the following steps: respectively polishing the surface of stainless steel by 400#, 800#, 1200#, 2000# abrasive paper to remove a surface oxide layer, then sequentially performing ultrasonic cleaning on the surface of the polished stainless steel substrate for 15min by using deionized water, acetone, absolute ethyl alcohol and deionized water to remove residual impurities on the surface, and drying by nitrogen for later use;
(2) preparing an inverted cone-shaped pit-shaped microstructure on the surface of the stainless steel in the step (1) by adopting a laser etching technology, wherein the parameters of the laser etching technology are as follows: the pulse width is 300fs, the frequency is 1.5kHz, and the energy density is 2.2J/cm2The scanning speed is 1.5mm/s, and the scanning interval is 105 um. The diameter of the processed inverted cone pit-shaped microstructure is 75um, the central distance between adjacent pits is 105um, and the processing depth is 85 um;
(3) depositing a zinc oxide seed crystal layer on the surface of the microstructure in the step (2) by adopting atomic layer deposition equipment, wherein the reaction conditions of the atomic layer deposition process are as follows: the selection of the used precursor is dimethyl zinc and water, and the selection of the deposition substrate temperature is 125 ℃; the thickness of the zinc oxide film of a single deposition cycle was: 0.55 nm; the number of deposition cycles was: 1364 times, the deposition thickness of the zinc oxide film is 750 nm;
(4) the process for preparing the zinc oxide nanorod array structure by adopting a hydrothermal method comprises the following steps: placing a glass beaker filled with formamide water solution with the mass concentration of 8.5% in a water bath kettle, controlling the temperature to be 75 ℃, then soaking the stainless steel substrate (with the film-plated surface facing horizontally upwards) plated with the zinc oxide film in the step (3) in the glass beaker, simultaneously vertically placing a metal zinc sheet into the glass beaker, keeping the distance of the metal zinc sheet and the metal substrate plated with the zinc oxide film to be 3mm, taking the metal zinc sheet as a reaction system, and carrying out hydrothermal reaction for 24 hours to obtain the zinc oxide nano-rod with the regular hexagon side length of 400nm, the length of 6.5um and the distance between adjacent nano-rods of 650 nm;
(5) and (4) cleaning the stainless steel sample obtained in the step (4) with absolute ethyl alcohol and deionized water in sequence, drying the stainless steel sample with nitrogen, then putting the stainless steel sample into a muffle furnace for annealing treatment at 195 ℃ for 180min, and naturally drying and cooling to obtain the underwater bionic gas film drag reduction surface with the micro-nano structure.
The surface static contact angle of the underwater bionic gas film drag reduction surface prepared according to the implementation steps is 153.21 degrees as shown in fig. 1 (b), and compared with a common smooth surface, the average drag reduction rate of the underwater bionic drag reduction surface is 15.31 percent as shown in fig. 2 (b). Has ideal drag reduction effect.
Example 3
The preparation method of the metal-based underwater bionic gas film drag reduction surface comprises the following steps:
(1) stainless steel is used as a base material (40 mm multiplied by 2 mm), and the surface pretreatment process of the stainless steel comprises the following steps: respectively polishing the surface of stainless steel by 400#, 800#, 1200#, 2000# abrasive paper to remove a surface oxide layer, then sequentially performing ultrasonic cleaning on the surface of the polished stainless steel substrate for 15min by using deionized water, acetone, absolute ethyl alcohol and deionized water to remove residual impurities on the surface, and drying by nitrogen for later use;
(2) preparing an inverted cone-shaped pit-shaped microstructure on the surface of the stainless steel in the step (1) by adopting a laser etching technology, wherein the parameters of the laser etching technology are as follows: the pulse width is 300fs, the frequency is 1.5kHz, and the energy density is 2.2J/cm2The scanning speed is 1.5mm/s, and the scanning pitch is 115 um. The diameter of the processed inverted cone pit-shaped microstructure is 75um, the center distance between adjacent pits is 115um, and the processing depth is 85 um;
(3) depositing a zinc oxide seed crystal layer on the surface of the microstructure in the step (2) by adopting a radio frequency magnetron sputtering instrument, wherein the reaction condition of the radio frequency magnetron sputtering is as follows: ZnO ceramic (the purity is 99.99%) is selected as the sputtering target material; the substrate temperature is 85 ℃; the radio frequency power is 140W; the sputtering time is 45min, and the deposition thickness of the zinc oxide film is 750 nm;
(4) the process for preparing the zinc oxide nanorod array structure by adopting a hydrothermal method comprises the following steps: placing a glass beaker filled with formamide water solution with the mass concentration of 8.5% in a water bath kettle, controlling the temperature to be 75 ℃, then soaking the stainless steel substrate (with the film-plated surface facing horizontally upwards) plated with the zinc oxide film in the step (3) in the glass beaker, simultaneously vertically placing a metal zinc sheet into the glass beaker, keeping the distance of the metal zinc sheet and the metal substrate plated with the zinc oxide film to be 3mm, taking the metal zinc sheet as a reaction system, and carrying out hydrothermal reaction for 24 hours to obtain the zinc oxide nano-rod with the regular hexagon side length of 400nm, the length of 6.5um and the distance between adjacent nano-rods of 650 nm;
(5) and (4) cleaning the stainless steel sample obtained in the step (4) with absolute ethyl alcohol and deionized water in sequence, drying the stainless steel sample with nitrogen, then putting the stainless steel sample into a muffle furnace for annealing treatment at 195 ℃ for 180min, and naturally drying and cooling to obtain the underwater bionic gas film drag reduction surface with the micro-nano structure.
The static contact angle of the surface of the underwater bionic gas film drag reduction surface prepared according to the implementation steps is 153.02 degrees as shown in figure 1 (c), compared with the average drag reduction rate of a common smooth surface, the average drag reduction rate of the underwater bionic gas film drag reduction surface is 15.15 percent, as shown in figure 2 (c), and the underwater bionic gas film drag reduction surface has a relatively ideal drag reduction effect.
Example 4
The preparation method of the metal-based underwater bionic gas film drag reduction surface comprises the following steps:
(1) stainless steel is used as a base material (40 mm multiplied by 2 mm), and the surface pretreatment process of the stainless steel comprises the following steps: respectively polishing the surface of stainless steel by 400#, 800#, 1200#, 2000# abrasive paper to remove a surface oxide layer, then sequentially performing ultrasonic cleaning on the surface of the polished stainless steel substrate for 15min by using deionized water, acetone, sewage ethanol and deionized water to remove residual impurities on the surface, and drying by nitrogen for later use;
(2) preparing an inverted cone-shaped pit-shaped microstructure on the surface of the stainless steel in the step (1) by adopting a laser etching technology, wherein the parameters of the laser etching technology are as follows: the pulse width is 300fs, the frequency is 1.5kHz, and the energy density is 2.2J/cm2The scanning speed is 1.5mm/s, and the scanning interval is 125 um. The diameter of the processed inverted cone pit-shaped microstructure is 75um, the central distance between adjacent pits is 125um, and the processing depth is 85 um;
(3) depositing a zinc oxide seed crystal layer on the surface of the microstructure in the step (2) by adopting a radio frequency magnetron sputtering instrument, wherein the reaction condition of the radio frequency magnetron sputtering is as follows: ZnO ceramic (the purity is 99.99%) is selected as the sputtering target material; the substrate temperature is 85 ℃; the radio frequency power is 140W; the sputtering time is 45min, and the deposition thickness of the zinc oxide film is 750 nm;
(4) the process for preparing the zinc oxide nanorod array structure by adopting a hydrothermal method comprises the following steps: placing a glass beaker filled with formamide water solution with the mass concentration of 8.5% in a water bath kettle, controlling the temperature to be 75 ℃, then soaking the stainless steel substrate (with the film-plated surface facing horizontally upwards) plated with the zinc oxide film in the step (3) in the glass beaker, simultaneously vertically placing a metal zinc sheet into the glass beaker, keeping the distance of the metal zinc sheet and the metal substrate plated with the zinc oxide film to be 3mm, taking the metal zinc sheet as a reaction system, and carrying out hydrothermal reaction for 24 hours to obtain the zinc oxide nano-rod with the regular hexagon side length of 400nm, the length of 6.5um and the distance between adjacent nano-rods of 650 nm;
(5) and (4) cleaning the stainless steel sample obtained in the step (4) with absolute ethyl alcohol and deionized water in sequence, drying the stainless steel sample with nitrogen, then putting the stainless steel sample into a muffle furnace for annealing treatment at 195 ℃ for 180min, and naturally drying and cooling to obtain the underwater bionic gas film drag reduction surface with the micro-nano structure.
The surface static contact angle of the underwater bionic gas film drag reduction surface prepared according to the implementation steps is 152.52 degrees as shown in figure 1 (d), compared with the average drag reduction rate of a common smooth surface, the underwater bionic gas film drag reduction surface has 14.93 percent of average drag reduction rate as shown in figure 2 (d), and has ideal drag reduction effect.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.
Claims (6)
1. A metal-based underwater bionic gas film drag reduction surface comprises a metal substrate, and is characterized by also comprising a pit-shaped microstructure arranged on the surface of the metal substrate and a zinc oxide nanorod array arranged on the surface of the pit-shaped microstructure;
the metal matrix is selected from one of a pure aluminum matrix, an aluminum alloy matrix, a red copper matrix and a stainless steel matrix;
the pit-shaped microstructure is selected from one of a semicircular pit-shaped microstructure, a square pit-shaped microstructure and an inverted cone pit-shaped microstructure;
the diameter of the semicircular pit-shaped microstructure is 35-75 μm, the center distance between adjacent pits is 75-140 μm, and the processing depth is 45-85 μm;
the side length of the square pit-shaped microstructure is 30-70 mu m, the central distance between adjacent pits is 70-140 mu m, and the processing depth is 45-85 mu m;
the diameter of the inverted cone pit-shaped microstructure is 35-75 μm, the center distance between adjacent pits is 75-140 μm, and the processing depth is 45-85 μm;
the metal-based underwater bionic air film drag reduction surface adsorbs air in water to form a layer of stable air film, so that the drag reduction effect is realized;
the cross section of the zinc oxide nano rod is in a regular hexagon, the side length of the regular hexagon is 150nm-400nm, the length of the zinc oxide nano rod is 2.5 mu m-6.5 mu m, and the distance between adjacent zinc oxide nano rods is 450nm-700 nm;
the bionic air film drag reduction surface is processed on the surface of an underwater navigation body or the surface of the bottom of a ship.
2. The metal-based underwater bionic gas film drag reduction surface according to claim 1, wherein the dimple-shaped microstructure is a semicircular dimple-shaped microstructure, the diameter of the semicircular dimple-shaped microstructure is 65 μm, the center distance between adjacent dimples is 95 μm, the processing depth is 75 μm, the cross section of the zinc oxide nanorod is in the shape of a regular hexagon, the side length of the regular hexagon is 300nm, the length of the zinc oxide nanorod is 5.5 μm, and the distance between adjacent zinc oxide nanorods is 550 nm;
or the pit-shaped microstructure is a square pit-shaped microstructure, the side length of the square pit-shaped microstructure is 55 micrometers, the central distance between adjacent pits is 100 micrometers, the processing depth is 65 micrometers, the cross section of the zinc oxide nanorod is a regular hexagon, the side length of the regular hexagon is 350nm, the length of the zinc oxide nanorod is 5 micrometers, and the distance between adjacent zinc oxide nanorods is 650 nm;
or the pit-shaped microstructure is an inverted cone pit-shaped microstructure, the diameter of the inverted cone pit-shaped microstructure is 75 micrometers, the center distance between adjacent pits is 115 micrometers, the processing depth is 85 micrometers, the cross section of the zinc oxide nanorod is in the shape of a regular hexagon, the side length of the regular hexagon is 400nm, the length of the zinc oxide nanorod is 6.5 micrometers, and the distance between adjacent zinc oxide nanorods is 650 nm.
3. A method of preparing a metal-based underwater biomimetic gas film drag reducing surface as described in claim 1 or 2, comprising the steps of:
1) and the surface pretreatment process of the metal matrix comprises the following steps: polishing the surface of the metal matrix by using abrasive paper, cleaning the polished surface of the metal matrix, and drying for later use;
2) preparing the surface in the step 1) into a metal base surface with a pit-shaped microstructure by adopting a laser etching processing technology;
3) depositing a zinc oxide seed crystal layer on the surface of the step 2) by adopting a deposition process;
4) growing a zinc oxide nanorod array structure on the surface of the step 3) by adopting a hydrothermal method;
5) annealing the metal matrix obtained in the step 4) to obtain the underwater bionic gas film drag reduction surface of the metal matrix.
4. The method for preparing the metal-based underwater bionic gas film drag reduction surface according to claim 3, wherein the parameters of the laser etching process in the step 2) are as follows: the pulse width is (300 +/-100) fs, the frequency is 1.5kHz, and the energy density is 2.2J/cm2The scanning speed is 1.5mm/s, and the scanning interval is 70-140 μm.
5. The method for preparing the metal-based underwater bionic gas film drag reduction surface according to claim 3, wherein the step 4) specifically comprises the following steps: placing a glass beaker containing formamide water solution with the mass concentration of 7-12% in a water bath kettle, controlling the temperature to be 55-95 ℃, then soaking the metal substrate deposited with the zinc oxide seed crystal layer in the step 3) in the glass beaker, enabling the surface of the zinc oxide seed crystal layer plated to be horizontally upward, vertically placing a metal zinc sheet into the glass beaker, keeping the distance between the metal zinc sheet and the metal substrate deposited with the zinc oxide seed crystal layer to be 3-10mm, and taking the metal zinc sheet as a reaction system, wherein the hydrothermal reaction time is 24-36 h.
6. The use of the metal-based underwater biomimetic gas film drag reducing surface according to claim 1 or 2, wherein the metal-based underwater biomimetic gas film drag reducing surface is machined on the surface of an underwater vehicle or the surface of the bottom of a ship.
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