CN116376430A

CN116376430A - Anti-icing coating based on oil-based magnetized microneedles, and preparation method and application thereof

Info

Publication number: CN116376430A
Application number: CN202310307877.4A
Authority: CN
Inventors: 李津津; 张瑞
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2023-03-27
Filing date: 2023-03-27
Publication date: 2023-07-04
Anticipated expiration: 2043-03-27
Also published as: CN116376430B

Abstract

The application discloses an anti-icing coating based on oil-based magnetized microneedles, and a preparation method and application thereof, wherein the preparation method of the anti-icing coating comprises the following steps: s1: pretreating the surface of the base material to enable the roughness of the surface of the base material to be 2-15 mu m; s2: adding the oil-based nano ferroferric oxide magnetic liquid into diluted resin, and uniformly dispersing to prepare a colloid solution; s3: transferring the colloid solution to the surface of a substrate, and forming a magnetic microneedle array on the surface of the substrate under the action of a magnetic field with the magnetic field strength of 3000-5000 gauss; s4: and (3) curing and forming under the action of a magnetic field with the magnetic field strength of 3000-5000 gauss to obtain the anti-icing coating. The invention can realize the preparation on the surface of a common base material, has extremely low ice adhesion capability and extremely good photo-thermal effect, and further delays the icing time to a great extent.

Description

Anti-icing coating based on oil-based magnetized microneedles, and preparation method and application thereof

Technical Field

The invention belongs to the technical field of functional material preparation, and particularly relates to an anti-icing coating based on oil-based magnetized microneedles, and a preparation method and application thereof.

Background

Ice formation from traffic systems, infrastructure to energy systems often creates catastrophic safety issues and significant economic losses. Anti-icing surfaces have a crucial impact on human daily life, but at the same time creating a stable, strong surface for low temperature environments or local low temperatures is still difficult to achieve, and current anti-icing/deicing strategies mainly include both active and passive directions.

In the related art, many active anti-icing and deicing strategies, such as electrothermal or steam heating melting, deicing chemicals, mechanical forces, etc., are applied to cold surfaces in sub-zero environments, such as aircraft wings, ship decks, wind turbine blades, windows and windshields, snow and ice on winter roads, etc. However, such active deicing strategies often face one or more of high cost, low aging, high energy consumption, complex design, environmental pollution, and the like.

Passive deicing mainly includes the following three modes: the super-hydrophobic surface can capture air, form air pockets at the solid-liquid interface, and reduce the effective contact area of supercooled liquid drops and a cold solid substrate to the greatest extent so as to inhibit icing, but at the same time, the interface has the defect of forming a high-energy solid-liquid interface, and at a lower temperature, the interface can promote heterogeneous nucleation of ice, damage air pockets in the structure, further cause higher ice adhesion strength, and has the defects of fragile microstructure and insufficient stability. The liquid is injected into the smooth surface, so that air pockets in the smooth surface are converted into an additivable oil film or other low-temperature non-icing liquid which is not mutually soluble with water on the basis of the super-hydrophobic surface, water and the material surface are effectively prevented from being frozen in contact, and the durability of the injected liquid into the smooth surface is still a challenge due to migration, evaporation or leakage of the injected liquid. The gel material is used for resisting ice and mainly comprises three types of hydrogel, ionic gel, organic gel and the like, wherein the hydrogel is mainly formed by adding an anti-freezing additive such as ethylene glycol and the like into a network structure, and a polymer network is designed to further control the existence of a non-frozen interface water lubrication layer at the interface of the hydrogel so as to further reduce the adhesion of ice on the surface; the organogel promotes crack growth of the interface and the ice to realize surface anti-icing mainly through the characteristics of unbalanced modulus, incompatible deformation and the like between the organogel and the ice; ionic gels resist icing by the lubricating effect of hydrophobic ionic liquids and their low crystallization point effect. However, the gel structure and the surface of the three basic configurations have the defects of poor adhesion with the substrate, lower mechanical strength and unsustainable property.

Disclosure of Invention

Aiming at the problems of high preparation cost, complex preparation process, poor anti-icing performance and robustness of most coatings in the related technology. The present invention aims to solve at least one of the technical problems in the related art to a certain extent, and therefore, an object of a first aspect of an embodiment of the present invention is to provide a method for preparing an anti-icing coating with an oil-based magnetized microneedle array.

It is an object of a second aspect of embodiments of the present invention to provide an anti-ice coating prepared by the above-described preparation method.

It is an object of a third aspect of embodiments of the present invention to provide the use of an anti-ice coating as described above.

The embodiment of the invention provides a preparation method of an anti-icing coating, which comprises the following steps:

s1: pretreating the surface of the base material to enable the roughness of the surface of the base material to be 2-15 mu m;

s2: adding the oil-based nano ferroferric oxide magnetic liquid into diluted resin, and uniformly dispersing to prepare a colloid solution;

s3: transferring the colloid solution to the surface of a substrate, and forming a magnetic microneedle array on the surface of the substrate under the action of a magnetic field with the magnetic field strength of 3000-5000 gauss;

s4: and (3) continuously curing and forming under the action of a magnetic field with the magnetic field strength of 3000-5000 gauss to obtain the anti-icing coating.

In some embodiments, the magnetic microneedles in the magnetic microneedle array are wide-bottomed and sharp-pointed microneedles with an inclination of 15-90 degrees, a length of 200-900 μm, and a microneedle density of 300-800 microneedles/cm ² 。

Preferably, the magnetic microneedles in the magnetic microneedle array are in a bevel cone shape, the inclination is 30-60 degrees, and the outer diameter of the bottom is 150-250 microns.

In some embodiments, the oil-based nano-ferroferric oxide magnetic liquid is prepared by dissolving the ferroferric oxide nanoparticles in an oil-based base solvent, wherein:

in some embodiments, the mass fraction of the ferroferric oxide nanoparticles is 25-40%.

In some embodiments, the particle size of the ferroferric oxide nanoparticles is 20 to 50nm.

In some embodiments, the oily base solvent is one or more of a perfluoropolyether, silicone oil, or paraffinic oil.

In some embodiments, in the colloidal solution, the volume ratio of the oil-based nano-ferroferric oxide magnetic liquid to the diluted resin is (1-2): 1.

in some embodiments, the colloidal solution is applied in an amount of 200 to 350. Mu.l/cm ² Preferably, the colloidal solution is applied in an amount of 200 to 300. Mu.l/cm ² 。

In some embodiments, the diluted resin is prepared by diluting a high temperature curable resin or a photocurable resin with a diluting solvent; wherein:

in some embodiments, the high temperature curable resin is one or more of polydimethylsiloxane, amorphous fluoropolymer, polytetrafluoroethylene, and polytrifluoroethylene; preferably, the high temperature cured resin is polydimethylsiloxane.

In some embodiments, the photocurable resin is a bisphenol a epoxy acrylate or urethane acrylate.

In some embodiments, the diluent solvent is one or more of tetrahydrofuran, toluene, methylene chloride, ethyl acetate.

In some embodiments, the volume ratio of the high temperature curable resin or the photocurable resin to the diluent solvent is 1 (0.5-1).

In some embodiments, in step S1, the pretreatment is a surface blasting treatment or an acid etching treatment.

In some embodiments, in step S2, the dispersion is an ultrasonic treatment, the frequency of the ultrasonic treatment is 20-30 kHz, and the time is 6-8 hours.

In some embodiments, when the diluted resin in the step S2 is selected to be a high-temperature cured resin, the curing and molding conditions in the step S4 are that the diluted resin is heated and cured for 1 to 2 hours at a temperature of between 100 and 120 ℃; when the diluted resin in the step S2 selects the photo-curing resin, the curing and molding conditions in the step S4 are that the ultraviolet light with the wavelength of 320-400 nm is used for curing for 1h.

In some embodiments, the substrate is selected from a metallic material, a non-metallic material, an inorganic material, an organic material, or a composite material.

The embodiment of the invention also provides an anti-ice coating, which is prepared by the preparation method.

The embodiment of the invention also provides application of the anti-icing coating, and the anti-icing coating is used in the fields of electric power, traffic, communication or aviation.

In some embodiments, the anti-icing coating described above is used for heat exchanger anti-icing, wind turbine blade anti-icing, vehicle anti-icing, marine anti-icing, aircraft surface anti-icing, or power and communications equipment anti-icing.

The embodiment of the invention has the following advantages and beneficial effects:

the embodiment of the invention provides an anti-icing coating of a flexible organic gel-based magnetic microneedle array with a photo-thermal effect and a preparation method thereof, and the embodiment of the invention actively realizes the surface temperature rise of the coating by utilizing solar energy in nature through an active and passive combination mode, namely through the photo-thermal effect of the coating, thereby delaying icing; and passively, the oily ferrofluid prepared by combining resin and oil-based magnetic particles is magnetized by a magnetic field and is further cured at high temperature to obtain the water-repellent and low-ice adhesion characteristics of the flexible microneedle array coating. The preparation on the surface of the common base material (such as AL, GCr15, stainless steel, glass, silicon wafer and the like) can be realized through the combination of the two, and the preparation has extremely low ice adhesion capability and extremely good photo-thermal effect, so that the icing time is greatly delayed.

Drawings

The foregoing and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a representation of the preparation of an anti-icing coating according to example 1;

FIG. 2 shows water contact angles of the coatings prepared in example 1 and example 4;

FIG. 3 is a schematic diagram of an ice adhesion strength test apparatus employed in an embodiment of the present invention;

FIG. 4 is a physical diagram of the anti-icing coating prepared in comparative example 2;

FIG. 5 is a physical diagram of comparative example 3 for preparing an anti-ice coating;

FIG. 6 is a graph of the ice adhesion strength versus the coating of example 1, the coating of comparative example 1, and specular aluminum flake;

FIG. 7 is a graph comparing ice adhesion strength of the coating of example 2, mirror GCr15 sheet;

FIG. 8 is a graph showing the comparison of ice adhesion strength of a mirror silicon wafer according to example 3;

FIG. 9 is an anti-ice adhesion strength plot of the coating of example 4;

FIG. 10 is an anti-ice adhesion strength plot of the coating of example 5;

FIG. 11 is a graph of the ice adhesion strength of the coatings of comparative example 2 and comparative example 3;

FIG. 12 is a graph comparing ice adhesion strength of the coating of example 1 and the coating of example 4 for different test angles of the inclined microneedles;

FIG. 13 is a graph showing the comparative photo-thermal effect of example 1 with or without an anti-icing coating;

FIG. 14 is a graph showing the change in ice adhesion strength of example 1 with or without an ice-resistant coating substrate under the photo-thermal effect;

FIG. 15 is a graph comparing the delay time of icing for example 1 with or without an anti-icing coating.

Detailed Description

The following detailed description of embodiments of the invention is exemplary and intended to be illustrative of the invention and not to be construed as limiting the invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

In this document, the term "and/or" is merely an association relation describing an associated object, meaning that there may be three relations, e.g. a and/or B, which may mean: a exists alone, A and B exist together, and B exists alone.

The term "plurality" herein refers to two or more (including two).

Where a value is described herein as a range, it is understood that such disclosure includes disclosure of all possible sub-ranges within the range, as well as specific values falling within the range, regardless of whether the specific value or sub-range is explicitly recited.

In this context, the terms "about", "left and right" refer to +/-10% of the recited values.

Unless otherwise indicated, the starting materials and reagents used in the following examples were either commercially available or may be prepared by known methods.

In a specific example, the magnetic field strengths of steps S3, S4 are the same, such as, without limitation: the magnetic field strength may be 3000 gauss, 3500 gauss, 4000 gauss, 4500 gauss, 5000 gauss, etc.

In some embodiments, the magnetic microneedles in the magnetic microneedle array are bottom-wide, top-pointed microneedles with a slope of 15-90 °, a length of 200-900 μm, and a microneedle density of 300-800 pins/cm ² . Non-limiting examples are: the inclination may be 15 °, 30 °, 45 °, 60 °, 90 °, etc. The length (average) may be 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, etc.; the microneedle density (average) may be 300 roots/cm ² 400 roots/cm ² 450 roots/cm ² 500 roots/cm ² 600 roots/cm ² 800 roots/cm ² Etc.

Preferably, the magnetic microneedles in the magnetic microneedle array are in an inclined cone shape, the inclination is 30-60 degrees, and the outer diameter of the bottom is 150-250 μm.

In some embodiments, the oil-based nano-ferroferric oxide magnetic liquid is prepared by dissolving ferroferric oxide nanoparticles in an oil-based base solvent, wherein:

in some embodiments, the mass fraction of the ferroferric oxide nanoparticles is 25-40%. Non-limiting examples are: the mass fraction may be 25%, 30%, 32%, 35%, 40%, etc.

In some embodiments, the particle size of the ferroferric oxide nanoparticles is 20 to 50nm. Non-limiting examples are: the particle size may be 20nm, 30nm, 35nm, 40nm, 50nm, etc.

In one specific example, the oil-based nano-ferroferric oxide magnetic liquid is a perfluoropolyether magnetic liquid containing 40wt.% of ferroferric oxide having an average particle size of 30 nm.

In some embodiments, the volume ratio of the oil-based nano-ferroferric oxide magnetic liquid to the diluent resin in the colloidal solution is (1-2): 1. non-limiting examples are: the volume ratio may be 1:1, 1.2:1, 1.4:1, 1.5:1, 2:1, etc.

In some embodiments, the colloidal solution is applied in an amount of 200 to 350. Mu.l/cm ² . Non-limiting examples are: the coating amount of the colloidal solution was 200. Mu.l/cm ² 、250μl/cm ² 、280μl/cm ² 、300μl/cm ² 、330μl/cm ² 、350μl/cm ² Etc.; preferably, the colloidal solution is applied in an amount of 200 to 300. Mu.l/cm ² . The colloidal solution was required to ensure a certain coating amount, and the coating amount was too small, and the magnetic field was not magnetized to form a visible microneedle, and the microneedle showed only a very small bulge. The oil-based magnetic micro-needles are formed only in the inner local area after the magnetic field is magnetized due to too much coating amount, and the micro-needles are coarse in appearance, uneven in distribution and too dispersed. Too much or too little coating is detrimental to the microneedle array's crack growth promoting effect upon ice cracking. The coating amount of the colloidal solution is controlled to be 200-350 mu l/cm ² The uniform magnetic microneedle array can promote crack growth when the icicle breaks away from the coating, and further reduce the adhesion of ice on the surface. And the coating amount of the colloid solution is 200-300 mu l/cm ² The effect is better.

In some embodiments, the dilution resin is prepared by diluting a high temperature curable resin or a photocurable resin with a dilution solvent; wherein:

in some embodiments, the high temperature curable resin is one or more of polydimethylsiloxane, amorphous fluoropolymer, polytetrafluoroethylene, and polytrifluoroethylene; preferably, the high temperature curable resin is polydimethylsiloxane.

In some embodiments, the volume ratio of the high temperature curable resin or photocurable resin to the diluent solvent is 1 (0.5-1).

In some embodiments, in step S1, the pretreatment is a surface blasting treatment or an acid etching treatment such that the roughness of the substrate surface is 2 to 15 μm. Non-limiting examples are: roughness levels of about 2 μm, 6 μm, 8 μm, 9 μm, 10 μm, 12 μm, 15 μm, etc. are achieved for surface uniformity.

In some embodiments, in step S2, the dispersion is an ultrasonic treatment, the frequency of the ultrasonic treatment is 20-30 kHz, and the time is 6-8 hours. Non-limiting examples are: the frequency of the ultrasonic treatment can be 20kHz, 25kHz, 30kHz, etc., and the time can be 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, etc.

It will be appreciated that in step S3, the strong magnet may be used to attract and disperse the droplets of the colloidal solution, and the position of the colloidal solution coated with the sample of the colloidal solution above the magnet and the distance from the surface of the magnet may be changed to position the colloidal solution at the magnetic induction line with different directions and intensities, so as to prepare the magnetic microneedle arrays with different lengths and inclinations.

In some embodiments, in step S3, the colloidal solution is transferred to the surface of the substrate, and spin coating or natural dripping leveling may be used.

In some embodiments, the substrate is selected from a metallic material, a non-metallic material, an inorganic material, an organic material, or a composite material. For example, the substrate may be an Al sheet, high chromium bearing steel, stainless steel, glass or silicon sheet.

In a second aspect, the embodiment of the invention also provides an anti-icing coating, which is prepared by the preparation method.

In a third aspect, the embodiment of the invention also provides an application of the anti-icing coating, and the anti-icing coating is used in the fields of electric power, traffic, communication or aviation.

In some embodiments, the anti-icing coating is used for heat exchanger anti-icing, wind turbine blade anti-icing, vehicle anti-icing, marine anti-icing, aircraft surface anti-icing, or power and communications equipment anti-icing.

The following are non-limiting examples and comparative examples of the present invention. Wherein:

perfluoropolyether type nano ferroferric oxide magnetic liquid: purchased from: hangzhou Jikang New Material Co., ltd;

silicone oil type nano ferroferric oxide magnetic liquid: purchased from: hangzhou Jikang New Material Co., ltd;

polydimethylsiloxane (PDMS) resin: model SYLGARDTM, 184, purchased from: the company America Conning; comprises basic components and curing agent.

AF1601 resin: model TeflonTM AF1601, available from Chemours, inc. of America.

Permanent magnet: high temperature resistant permanent magnet.

In the embodiment of the invention, the ice adhesion strength is tested by adopting the ice adhesion strength testing device. As shown in fig. 2, the ice adhesion strength testing device comprises an ambient temperature control cabinet, a cooling table, an icing icicle model (phi 1cm x 5 mm), a stepping push rod and a force transducer,

in the test process, the temperature of a cooling table is controlled at-25 ℃, the temperature of an environmental temperature control cabinet is set at-10 ℃, a sample and an icing icicle mould are placed in the surface of the cooling table, and 1ml of water is dripped into the icicle mould; and (3) standing for 5min, after water cooling and icing, adjusting the stepping push rod carrying the force transducer to the tangent plane of the icicle model, wherein the center of the push rod head is 1-2 mm away from the tangent plane, and the height is 1mm away from the surface of the sample.

And (3) starting the test, controlling the stepping push rod and the force transducer to move at the speed of 0.2mm/s until the ice column is subjected to interfacial shearing cracking movement, stopping the push rod, analyzing and calculating the obtained force measurement data, and dividing the peak value of the instant force during cracking by the icing area (the area of a phi 1cm circle) of the ice column to obtain ice adhesion strength data.

In the embodiment of the invention, the experimental xenon lamp is used for simulating the irradiation of sunlight to the coating sample, and the irradiation of sunlight (namely the illumination intensity is 96 mW/cm) ² ) Distance coatingWhen the surface of the layer is 10cm and the temperature of a cooling table (namely a sample substrate) is-10 ℃, the surface temperature of the sample is measured by using a Kawav infrared thermal imager to test the photo-thermal effect of the sample.

In the embodiment of the invention, the high-delay icing performance of the obtained coating is tested by utilizing a video contact angle measuring instrument and a cooling table, and the icing delay performance of the coating under the effect of photo-thermal effect is tested by combining the irradiation of a xenon lamp.

Example 1:

a method of preparing an anti-icing coating comprising the steps of:

selecting a mirror surface Al sheet with the size of 1.5cm 1mm as a base material, and adopting sand blasting to realize the surface roughness of about 5 mu m;

3ml of perfluoropolyether type nano ferroferric oxide magnetic liquid (containing 40wt.% of ferroferric oxide nano particles with the average particle size of 30 nm) is added into a mixed liquid of 1ml of tetrahydrofuran and 1ml of AF1601 resin, and the mixed liquid is subjected to ultrasonic treatment for 6 hours to uniformly disperse the mixed liquid; obtaining a colloid solution;

and (3) dripping 600 mu l of the obtained colloid solution on the surface of the sand-blasted aluminum sheet obtained in the step (1) to naturally level, placing a sample above the permanent magnet at a position which is 1cm-1.5cm away from the surface of the permanent magnet, wherein the center position of the sample is positioned at a position with radius R=1.5 cm of the permanent magnet (the size of the permanent magnet is phi 6cm x 2cm (radius is 3 cm), and the magnetic field strength is 3900 gauss), and magnetizing the sample to form a magnetic microneedle array with an inclination angle of about 45 degrees.

And (3) integrally placing the magnet and the sample on a high-temperature heating table, heating to 100 ℃ and keeping for 2 hours, and then air-cooling for 10 hours to obtain the anti-icing coating. Example 1 the final anti-ice coated magnetic microneedle array was prepared at an angle of inclination of about 45 deg., an average length of about 500 μm, and an average microneedle density of about 400 pins/cm ² 。

Example 2:

a method of preparing an anti-icing coating comprising the steps of:

selecting a mirror surface GCr15 sheet with the size of 1.5cm 1mm as a base material, and adopting an acid etching means to realize the level roughness of the surface of about 10 mu m;

3ml of silicone oil type nano ferroferric oxide magnetic liquid (containing 40wt.% of ferroferric oxide nano particles with the average particle size of 30 nm) is added into a mixed liquid of 1ml of toluene and 1ml of PDMS resin (polydimethylsiloxane), and the mixed liquid is subjected to ultrasonic treatment for 6 hours to uniformly disperse the mixed liquid; obtaining a colloid solution;

and (3) dripping 600 mu l of the obtained colloidal solution on the surface of the GCr15 subjected to sand blasting treatment obtained in the step (1) to naturally level, placing a sample above a permanent magnet at a distance of 1cm-1.5cm from the surface of the permanent magnet, wherein the center position of the sample is positioned at a radius R=1cm of the permanent magnet (the size of the permanent magnet is phi 6cm x 2cm, and the magnetic field strength is 3900 gauss), and magnetizing the magnetic field to form a magnetic microneedle array with an inclination angle of about 60 degrees.

And (3) integrally placing the magnet and the sample on a high-temperature heating table, heating to 100 ℃ and keeping for 2 hours, and then air-cooling for 10 hours to obtain the anti-icing coating. Example 2 the final anti-iced coated magnetic microneedle array was tilted at about 60℃and had an average length of about 500. Mu.m, and an average microneedle density of about 500 roots/cm ² 。

Example 3:

a method of preparing an anti-icing coating comprising the steps of:

selecting a silicon wafer with the size of 1.5cm 0.5mm as a base material, and adopting sand blasting to realize the level roughness of the surface of about 2 mu m;

2ml of perfluoropolyether type nano ferroferric oxide magnetic liquid (containing 40wt.% of ferroferric oxide nano particles with the average particle size of 30 nm) is added into a mixed liquid of 1ml of tetrahydrofuran and 1ml of PDMS resin (polydimethylsiloxane), and the mixed liquid is subjected to ultrasonic treatment for 6 hours to uniformly disperse the mixed liquid; obtaining a colloid solution;

and (3) dripping 600 mu l of the obtained colloid solution on the surface of the silicon wafer subjected to sand blasting treatment obtained in the step (1) to naturally level, placing a sample above a permanent magnet at a position which is 1cm-1.5cm away from the surface of the permanent magnet, wherein the center position of the sample is positioned at a position with radius R=1.5 cm of the permanent magnet (the size of the permanent magnet is phi 6cm x 2cm, and the magnetic field strength is 3900 gauss), and magnetizing the sample to form a magnetic microneedle array with an inclination angle of about 45 degrees.

Placing the magnet and sample on a high temperature heating table, heating to 90deg.C, maintaining for 2 hr, and air coolingAnd (5) obtaining the anti-icing coating after 10 h. Example 3 the final anti-iced coated magnetic microneedle array was tilted at about 45℃and had an average length of about 500. Mu.m, and an average microneedle density of about 400/cm ² 。

Example 4

A method of preparing an anti-icing coating comprising the steps of:

and (3) dripping 750 μl of the obtained colloid solution on the surface of the sand-blasted aluminum sheet obtained in the step (1) to naturally level, placing the sample above the permanent magnet at a position 1cm-1.5cm away from the surface of the permanent magnet, wherein the center position of the sample is positioned at a position with radius R=1.5 cm of the permanent magnet (the size of the permanent magnet is phi 6cm x 2cm (radius is 3 cm), the magnetic field strength is 3900 gauss), and magnetizing the magnetic field to form a magnetic microneedle array with a uniform inclination angle of about 45 degrees, wherein the microneedles are coarser and slightly dispersed compared with those in the embodiment 1.

And (3) integrally placing the magnet and the sample on a high-temperature heating table, heating to 100 ℃ and keeping for 2 hours, and then air-cooling for 10 hours to obtain the anti-icing coating. Example 4 the final anti-ice coated magnetic microneedle array was tilted at about 45℃and had an average length of about 600. Mu.m, and an average microneedle density of about 300 roots/cm ² 。

Example 5

A method of preparing an anti-icing coating comprising the steps of:

and (3) dripping 600 mu l of the obtained colloid solution on the surface of the sand-blasted aluminum sheet obtained in the step (1) to naturally level, placing a sample above a permanent magnet at a position which is 1cm-1.5cm away from the surface of the permanent magnet, wherein the center position of the sample is positioned at a radius R=0cm of the permanent magnet (the size of the permanent magnet is phi 6cm x 2cm (the radius is 3 cm), and the magnetic field strength is 3900 gauss), and magnetizing the magnetic field to form a magnetic microneedle array with an inclination angle of about 90 degrees (namely vertical to a substrate).

And (3) integrally placing the magnet and the sample on a high-temperature heating table, heating to 100 ℃ and keeping for 2 hours, and then air-cooling for 10 hours to obtain the anti-icing coating. Example 5 the final anti-iced coated magnetic microneedle array was tilted at about 90 deg., and had an average length of about 300 μm and an average microneedle density of about 500 pins/cm ² 。

Comparative example 1

A method of preparing an anti-icing coating comprising the steps of:

and (3) dripping 600 mu l of the obtained colloidal solution on the surface of the sand-blasted aluminum sheet obtained in the step (1) to naturally level, then placing the aluminum sheet on a high-temperature heating table, heating to 100 ℃ and keeping for 2 hours, and then air-cooling for 10 hours to obtain a sample without the magnetic microneedle array.

Comparative example 2

A method of preparing an anti-icing coating comprising the steps of:

100 μl of the obtained colloidal solution was dropped on the surface of the sand-blasted aluminum sheet obtained in step (1), and the sample was placed above the permanent magnet at a height of 1cm-1.5cm from the surface and a radius r=1.5 cm (the permanent magnet has a size of phi 6cm x 2cm (radius 3 cm), and the magnetic field strength was 3900 gauss), but since the amount of the added colloidal solution was small and the content of the perfluoropolyether type nano-ferroferric oxide magnetic liquid was insufficient, no further visible microneedle was formed after the magnetic field magnetization, and the sample showed only a very small bulge shape. As shown in fig. 4.

And (3) integrally placing the magnet and the sample on a high-temperature heating table, heating to 100 ℃ and keeping for 2 hours, and then air-cooling for 10 hours to obtain the anti-icing coating.

Comparative example 3

A method of preparing an anti-icing coating comprising the steps of:

and (3) dripping 1000 μl of the obtained colloidal solution on the surface of the sand-blasted aluminum sheet obtained in the step (1), placing a sample above a permanent magnet at a position with a height of 1cm-1.5cm and a radius R=1.5 cm from the surface (the permanent magnet has a size of phi 6cm x 2cm (radius 3 cm), the magnetic field strength is 3900 gauss), and magnetizing the magnetic field to form magnetic microneedles with an inclination angle of about 45 degrees in an inner local area, wherein the microneedles are coarse in morphology, uneven in distribution and excessively dispersed. As shown in fig. 5.

FIG. 1 is a physical diagram and a cross-sectional representation of the preparation of an oil-based magnetic fluid microneedle array coating according to the embodiment 1 of the invention; FIG. 2 is a graph of water contact angles for the coatings of example 1 and example 4; as can be seen from fig. 1: the oil-based magnetic liquid is added in a preferable proportion and the amount, the prepared coating has obvious morphological characteristics of an inclined microneedle array, and as can be seen from fig. 2, after the oil-based magnetic liquid is mixed with resin to be cured and the microneedle array is formed, the coating has a water contact angle of 100-120 degrees, which is related to the synergistic effect that a thin oil film and low-surface energy resin can be separated out from the surface of the cured oil-based magnetic liquid, and the synergistic effect is a big cause for determining that the coating has low ice adhesion property.

Fig. 4 is a physical diagram of the coating prepared in comparative example 2, and it can be seen from fig. 4 that the micro-needles cannot be further formed in a visible state after the magnetization of the magnetic field due to the small amount of the added colloidal solution and the insufficient content of the perfluoropolyether type nano-ferroferric oxide magnetic liquid, and only have a very small bulge shape.

Fig. 5 is a physical diagram of the coating prepared in comparative example 3, and it can be seen from fig. 5 that the magnetic field is magnetized to form magnetic microneedles with an inclination angle of about 45 ° in an inner local area, but the microneedles are coarse in morphology, uneven in distribution and too dispersed.

FIGS. 6 to 8 show the change in the ice adhesion strength of the substrate with or without the ice-resistant coating in examples 1 to 3 and comparative example 1; it can be seen that: compared with the untreated substrate surface, the oil-based magnetic microneedle array coating prepared by the invention has larger amplitude reduction of ice adhesion strength, and the amplitude reduction is more than 95 percent; the ice adhesion strength of the coating prepared on the Al surface in the example 1 is 17KPa, the ice adhesion strength of the coating prepared on the GCr15 sheet in the example 2 and the ice adhesion strength of the coating prepared on the silicon sheet in the example 3 are smaller than 20KPa, and the coating has good ice resistance. This is mainly due to: 1) The low freezing point of the oil film separated out from the surface of the coating layer causes ice columns formed on the surface to be easily detached from the surface of the oil film. 2) The uniform magnetic microneedle array can promote crack propagation when the icicle breaks away from the coating, and further reduce the adhesion of ice on the surface. In comparative example 1, the ice adhesion strength of the surface of the control sample to which the magnetic microneedle array was not applied was high.

Fig. 9 shows that the coating of the colloidal solution prepared in example 4, which has a relatively uniform magnetic microneedle array, has relatively large and relatively dispersed microneedles on the surface of the coating, and has an ice adhesion strength of about 33KPa, which is reduced by 93% or more compared with the untreated substrate surface, and has a higher ice adhesion strength compared with example 1.

Fig. 10 shows a magnetic microneedle coating prepared by placing a sample with a colloidal solution at the center of a magnet in example 5, and the prepared microneedle array was perpendicular to the surface of the substrate due to the position specificity, and had an ice adhesion strength of about 52Kpa and a higher ice adhesion strength.

Fig. 11 shows the ice adhesion strength of the coating in comparative example 2 (ice adhesion strength 104 KPa) and comparative example 3 (ice adhesion strength 130 KPa), and it can be seen from the comparison that the ice adhesion strength of the uniform oil-based magnetic microneedle array prepared according to the examples of the present invention is much lower than that of comparative examples 2 to 3. This is mainly due to the fact that an appropriate amount of colloidal solution needs to be added to form the oil-based magnetic microneedle array, and the addition amount of the colloidal solution is too small, wherein the oil-based nano-ferroferric oxide magnetic liquid is insufficient in content, no visible microneedles can be further formed after the magnetic field is magnetized, and the oil-based nano-ferroferric oxide magnetic liquid only takes on a very small bulge shape. When the addition amount of the colloid solution is excessive, the oil-based magnetic microneedle is only formed in an inner local area after the magnetic field is magnetized, and the microneedle has coarse morphology, uneven distribution and over-dispersion. Both cases are unfavorable for the microneedle array to exert its crack growth promoting effect on ice cracking, thereby making the ice adhesion strength higher.

FIG. 12 shows the ice adhesion strength of the oil-based magnetic microneedle arrays prepared in examples 1 and 4 in different test directions, and it can be seen that both the uniform fine oil-based magnetic microneedle array formed in example 1 and the coarser magnetic microneedle array formed in example 4 have lower ice adhesion strength for the test against the oblique direction of the microneedles and relatively higher ice adhesion strength for the test against the oblique direction of the microneedles, because the oil-based magnetic microneedle arrays exhibit flexibility, when the icicles are pushed against the oblique direction of the microneedles, the tips of the oil-based magnetic microneedles are deformed first, and the deformation range is larger, which is more likely to cause and promote crack propagation between ice and surface, i.e., are shown to push ice off the surface more easily, and the ice adhesion strength is lower; when the oil-based magnetic microneedle is pushed along the inclined direction, the wide bottom of the oil-based magnetic microneedle is stressed firstly, is not easy to deform or has small deformation degree, and the crack of ice and the surface can be generated and expanded only by increasing the lateral pushing force, so that the larger ice adhesion strength can be caused. It can also be seen that the uniform, fine oil-based magnetic microneedle array of example 1 has more excellent anti-ice adhesion properties.

FIG. 13 is a photo-thermal effect comparison of example 1 with or without an anti-icing coating; as can be seen from fig. 13, the measured surface temperature of the sample was 15 ℃ higher than that of the conventional Al sheet.

Fig. 14 shows the ice adhesion strength of the oil-based magnetic microneedle array coating of example 1, which was tested after 2min of irradiation with a xenon lamp simulation "one sunlight", was further reduced to about 7 KPa. As can be analyzed in conjunction with fig. 13, the surface temperature of the coating gradually increases under the effect of the photo-thermal effect, and the ice bound to the surface gradually becomes local water molecules, and further gradually expands into a water film, which further exhibits lower ice adhesion strength upon testing.

Fig. 15 is a comparison of the icing time delay of the substrate with the anti-icing coating in example 1, and the icing time delay of the coating under the effect of the photo-thermal effect is tested by combining the irradiation of the xenon lamp on the basis of testing the high icing delay performance of the obtained coating by using a video contact angle measuring instrument and a cooling table, and as can be seen from fig. 15, the icing time of the substrate with the anti-icing coating in example 1 is prolonged by about 62 times of that of the aluminum sheet subjected to the sand blasting treatment.

For purposes of this disclosure, the terms "one embodiment," "some embodiments," "example," "a particular example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.

Claims

1. A method for preparing an anti-icing coating, comprising the steps of:

2. The method for preparing an anti-icing coating according to claim 1, wherein the magnetic microneedles in the magnetic microneedle array are microneedles with a bottom width and an upper tip, an inclination of 15-90 degrees, a length of 200-900 μm, and a microneedle density of 300-800 microneedles/cm ² ；

3. The method for preparing an anti-icing coating according to claim 1, wherein the oil-based nano-ferroferric oxide magnetic liquid is prepared by dissolving the nano-iron ferrooxide particles in an oil-based base solvent, wherein:

the mass fraction of the ferroferric oxide nano particles is 25-40%;

and/or, the particle size of the ferroferric oxide nano particles is 20-50 nm;

and/or the oily base solvent is one or more of perfluoropolyether, silicone oil or paraffin oil.

4. A process for the preparation of an anti-icing coating according to claim 1, wherein,

in the colloidal solution, the volume ratio of the oil-based nano ferroferric oxide magnetic liquid to the diluted resin is (1-2): 1, a step of;

and/or the coating amount of the colloid solution is 200-350 mu l/cm ² Preferably, the colloidal solution is applied in an amount of 200 to 300. Mu.l/cm ² 。

5. The method for preparing an anti-icing coating according to claim 1, wherein the diluted resin is prepared by diluting a high-temperature cured resin or a photo-cured resin with a diluting solvent; wherein:

the high-temperature curing resin is one or more of polydimethylsiloxane, amorphous fluorine-containing polymer, polytetrafluoroethylene and polytrifluoroethylene; preferably, the high temperature cured resin is polydimethylsiloxane;

and/or the photo-curing resin is bisphenol A type epoxy acrylate or polyurethane acrylate;

and/or the diluting solvent is one or more of tetrahydrofuran, toluene, methylene dichloride and ethyl acetate;

and/or the volume ratio of the high-temperature curing resin or the photo-curing resin to the diluting solvent is 1 (0.5-1).

6. A process for the preparation of an anti-icing coating according to claim 1, wherein,

in the step S1, the pretreatment is surface sand blasting treatment or acid etching treatment;

and/or in the step S2, the dispersion is ultrasonic treatment, the frequency of the ultrasonic treatment is 20-30 kHz, and the time is 6-8 hours.

7. The method for preparing an anti-icing coating according to claim 5, wherein when the diluted resin in the step S2 is selected as the high-temperature curing resin, the curing and molding conditions in the step S4 are that the heat curing is carried out for 1 to 2 hours at 100 to 120 ℃; when the diluted resin in the step S2 selects the photo-curing resin, the curing and molding conditions in the step S4 are that the ultraviolet light with the wavelength of 320-400 nm is used for curing for 1h.

8. An anti-icing coating, characterized in that it is prepared by the preparation method described in claims 1 to 7.

9. Use of an anti-icing coating according to claim 8, characterized in that it is used in the electric, traffic, communication or aeronautical fields.

10. Use of an anti-icing coating according to claim 9 for heat exchanger anti-frost, wind turbine blade anti-icing, vehicle anti-icing, marine anti-icing, aircraft surface anti-icing or power and communications facilities anti-icing.