Magnetic field auxiliary directional heating coating as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of a magnetic field assisted directional heating coating, which comprises the following steps: S2, preparation of a heating heat-conducting layer: adding magnetic graphene, a first auxiliary agent, a diluent and a first surfactant into water-borne epoxy resin, and uniformly stirring to obtain mixed slurry; adding a curing agent into the mixed slurry, uniformly stirring to obtain a heating and heat-conducting coating, coating a bearing part with the heating and heat-conducting coating and wrapping the conductive electrode, magnetizing the bearing part in a magnetic field with the magnetic field intensity of 0.05-0.1 T for 30-60 minutes, and curing the bearing part at the temperature of 20-50 DEG C for 2-6 hours to form a heating and heat-conducting layer; s3, a heat insulation layer is prepared, specifically, the surface, away from the bearing part, of the heating heat conduction layer is coated with heat insulation foam to form the heat insulation layer, and then room temperature curing is conducted for 2-6 h; wherein the first auxiliary agent comprises at least one of boron nitride, aluminum oxide and aluminum nitride; compared with the prior art, the obtained magnetic field-assisted directional heating coating can quickly remove ice and has a lightning protection effect.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a magnetic field assisted directional heating coating and a preparation method and application thereof. Background Art

[0002] As the global demand for renewable energy continues to grow, wind power generation, as a clean and renewable form of energy, has become increasingly important. However, in cold climates, the icing problem of wind turbine blades has become one of the key factors restricting the safe and efficient operation of wind farms. Blade icing not only leads to a significant decrease in power generation efficiency, but also may cause mechanical failures and even pose a threat to the safety of wind farms. Therefore, the research and application of wind power deicing technology is particularly important. The icing problem of wind turbine blades is particularly prominent in cold areas, and the annual power loss caused by icing can reach 5% to 25%. Traditional deicing methods such as mechanical deicing and chemical deicing have the disadvantages of low efficiency, high cost, and great damage to blades. Therefore, exploring new, efficient and environmentally friendly deicing technologies has become a research hotspot in the field of wind power. As a new deicing material, heating coating has broad application prospects because it can melt ice by heating itself in low temperature environments.

[0003] For example, CN109733017B discloses a composite material containing a graphene / resin / carbon fiber modified electric heating layer, a preparation method and use thereof, wherein the preparation method of the modified electric heating layer is:

[0004] (1) Preparing a graphene / thermoplastic resin blend: mechanically stirring graphene and thermoplastic resin powders in proportion for 30 minutes and placing them in an oven for drying for 6 hours, ball milling them in a planetary ball mill at a speed of 300 to 500 r / min for 4 to 6 hours until the powders are evenly mixed, and sieving to obtain a graphene / thermoplastic resin blend powder; wherein: the ball milling jar of the planetary ball mill is made of polytetrafluoroethylene plastic, and the grinding balls are zirconium oxide ceramics or cemented carbide balls with a diameter of 2 to 5 mm; the graphene is single-layer graphene and / or few-layer graphene obtained by mechanical exfoliation;

[0005] (2) preparing a graphene oxide dispersion: mixing graphene oxide powder and a dispersant in proportion, and performing ultrasonic dispersion treatment for 60 min at an ultrasonic power of 40 to 60 W to obtain a graphene oxide dispersion with a concentration of 0.5 to 5 g / L;

[0006] (3) Preparation of graphene oxide / carbon fiber monolayer by electrophoretic deposition: Conductive silver paste is uniformly coated on both edges of the carbon fiber cloth washed with deionized water, and the cloth is fastened under the anode copper clamping plate of the automatic electrophoretic deposition device and placed in an electrolyte tank, so that the graphene oxide dispersion in step (2) immerses the carbon fiber cloth but does not completely immerse the anode copper clamping plate, and the electrophoretic deposition process parameters are adjusted to perform anodic electrophoretic deposition to obtain a graphene oxide / carbon fiber monolayer, which is then blown dry for later use; wherein the electrophoretic deposition process parameters include: a DC voltage of 15 to 30 V, a deposition time of 5 to 15 min, and a deposition temperature of 40° C.;

[0007] (4) Preparing a modified electric heating layer: evenly spreading the graphene / thermoplastic resin blend described in step (1) and the graphene oxide / carbon fiber monolayer described in step (3).

[0008] The patented technology has the disadvantage that the preparation process of the modified electric heating layer is relatively complicated, and the heating rate of the electric heating layer prepared in this way is slow and cannot ensure rapid de-icing.

[0009] CN112745728B also discloses a method for preparing a water-based micro-nano graphite wind turbine blade deicing coating system. By coating the inner wall of the blade with a heat-generating coating, the heat transfer to the inner space of the wind turbine blade is slowed down while ensuring rapid deicing, thereby achieving energy-saving effects. However, the risk of lightning strikes on the blades is not taken into account, which is not conducive to the normal operation of the blades.

[0010] As summarized above, the existing heat-generating coatings do not comprehensively consider how to quickly heat up and de-ice and have excellent lightning protection performance. Summary of the invention

[0011] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a magnetic field-assisted directional heating coating and a preparation method and application thereof, so as to solve the problem in the prior art that the existing heating coatings do not comprehensively consider how to quickly heat up and de-ice and have excellent lightning protection performance.

[0012] To achieve the above object, the present invention adopts the following technical solution: The first aspect of the present invention adopts the following technical solution: A method for preparing a magnetic field assisted directional heating coating comprises the following steps:

[0013] S1. Arrange conductive electrodes

[0014] Laying a conductive electrode on a surface of the carrier;

[0015] S2. Preparation of heating thermal conductive layer

[0016] Adding magnetic graphene, a first auxiliary agent, a diluent and a first surfactant into a water-based epoxy resin and stirring evenly to obtain a mixed slurry;

[0017] Then, a curing agent is added to the mixed slurry, and the mixture is stirred to obtain a heating thermal conductive coating, the heating thermal conductive coating is coated on the carrier and the conductive electrode is coated therebetween, and then the coating is placed in a magnetic field with a magnetic field strength of 0.05 to 0.1 T for 30 to 60 minutes, and then the coating is placed at a temperature of 20 to 50° C. for curing for 2 to 6 hours to form a heating thermal conductive layer;

[0018] S3. Preparation of thermal insulation layer

[0019] Coating thermal insulation foam on the surface of the heating and heat-conducting layer away from the carrier to form a thermal insulation layer, and then curing at room temperature for 2 to 6 hours;

[0020] Wherein, the first auxiliary agent includes at least one of boron nitride, aluminum oxide and aluminum nitride.

[0021] Optimally, the components in the heating and thermally conductive layer are calculated by mass and include: 30% to 50% water-based epoxy resin, 10% to 30% magnetic graphene, 15% to 25% curing agent, 1% to 2% first surfactant, 5% to 15% first auxiliary agent and 10% to 35% diluent.

[0022] Optimally, the diluent includes at least one of water, acetone, styrene and dimethylformamide.

[0023] Preferably, the waterborne epoxy resin comprises at least one of bisphenol A epoxy resin, novolac epoxy resin, glycerol ether epoxy resin and amino epoxy resin.

[0024] Optimally, the curing agent includes at least one of m-phenylenediamine, dihexyltriamine, isophoronediamine, dipropylenetriamine and ethylenediamine.

[0025] Optimally, the thickness of the thermal insulation layer is 10-20 mm; the thickness of the heating and heat-conducting layer is 30-500 μm.

[0026] Optimally, the first surfactant includes at least one of sodium dodecyl sulfate, sodium fatty alcohol polyoxyethylene ether sulfate and fatty alcohol polyoxyethylene ether.

[0027] Optimally, the magnetic graphene includes graphene oxide and a second auxiliary agent, and the second auxiliary agent includes at least one of ferric chloride hexahydrate, ferric chloride tetrahydrate, ferrosoferric oxide, manganese zinc ferrite, nickel zinc ferrite and barium ferrite.

[0028] Optimized, the preparation method of the magnetic graphene is as follows:

[0029] preparing a graphene oxide stock suspension having a concentration of 2 to 3 mg / ml;

[0030] FeCl3·6H2O and FeCl2·4H2O in a molar ratio of 2:1 are dissolved in a hydrochloric acid solution to prepare a first mixed solution with a concentration of 0.1 to 0.2 mg / mL;

[0031] At room temperature, adding the prepared graphene oxide stock suspension dropwise to the prepared first mixed solution to form a second mixed solution;

[0032] NaOH solution is added dropwise to the second mixed solution until the pH value is 9-10 to obtain a black suspension, and the black suspension is heated to 60-80° C. and stirred for 10-30 minutes; then cooled to room temperature and washed with deionized water for multiple times until the pH value of the black suspension reaches neutral, and then filtered and dried to obtain magnetic graphene.

[0033] Optimally, the thermal insulation layer comprises, by weight: 45 to 80 parts of a polyol compound, 40 to 60 parts of a polyisocyanate compound, 1 to 5 parts of a foaming agent, 0.1 to 1 part of a second surfactant, and 1 to 5 parts of a catalyst.

[0034] Preferably, the polyol compound comprises at least one of polyether diol and polyester polyol.

[0035] Preferably, the polyisocyanate compound comprises at least one of diphenylmethane diisocyanate and toluene diisocyanate.

[0036] Optimally, the foaming agent includes at least one of water, carbon dioxide foaming agent, hydrogen chloride foaming agent and ammonia foaming agent.

[0037] Preferably, the catalyst comprises at least one of triethanolamine and triethylenediamine.

[0038] Optimally, the second surfactant includes at least one of silicone oil, sodium dodecylbenzene sulfonate and sodium α-olefin sulfonate.

[0039] The second aspect of the present invention adopts the following technical solution: a magnetic field assisted directional heating coating is prepared by the preparation method of the magnetic field assisted directional heating coating described in the first aspect of the present invention.

[0040] The third aspect of the present invention adopts the following technical solution: an application of the magnetic field assisted directional heating coating as described in the second aspect of the present invention, wherein the magnetic field assisted directional heating coating is fixed with epoxy resin glue and powered on for deicing.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. High-efficiency heating performance: Magnetic graphene is oriented after being magnetized in a magnetic field. This arrangement not only improves the uniformity of the distribution of magnetic graphene in the magnetic field-assisted directional heating coating, but also enables the magnetic graphene in the magnetic field-assisted directional heating coating to more effectively transfer the heat generated by the heating thermal conductive layer, thereby accelerating the diffusion of heat and improving the deicing efficiency of the magnetic field-assisted directional heating coating. At the same time, the directional arrangement of magnetic graphene can also improve the flexibility and impact resistance of the magnetic field-assisted directional heating coating.

[0043] 2. Excellent thermal conductivity and insulation performance: Boron nitride has the advantages of thermal conductivity and insulation: Boron nitride has high thermal conductivity and good electrical insulation. Boron nitride is used to heat the thermal conductive layer, which can not only effectively conduct heat and ensure that heat is evenly distributed throughout the system, but also prevent current leakage and ensure the safe operation of the equipment. This dual characteristic makes boron nitride an irreplaceable role in heating elements.

[0044] 3. Advantages of fixed-point heating: Using epoxy resin glue to stick the coating to a specific location not only ensures the stability of the magnetic field-assisted directional heating coating, but also enhances the mechanical strength of the entire system. The insulating properties of epoxy resin glue help prevent current leakage and ensure the safety of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the process of oriented arrangement of magnetic graphene in a magnetic field in the present invention;

[0046] Figure 2 A schematic diagram of a magnetic field-assisted directional heating coating in the present invention;

[0047] Figure 3 Schematic diagram of the distribution of conductive electrodes in the heating and heat-conducting layer in the present invention.

[0048] The reference numerals in the drawings of the specification include: glass fiber cloth 1 , heating heat-conducting layer 2 , heat-insulating layer 3 , conductive electrode 4 , main electrode 41 , and branch electrode 42 . DETAILED DESCRIPTION

[0049] The present invention is further described in detail below through specific embodiments:

[0050] The present invention is further described in detail below through specific embodiments:

[0051] First of all, it should be noted that the present invention, by ingeniously integrating multiple technologies such as graphene, magnetic field treatment and fixed-point heating, has demonstrated a series of significant characteristics and many beneficial effects, which can be summarized as follows:

[0052] (a) High efficiency heating performance:

[0053] Advantages of graphene: As a two-dimensional material, graphene has extremely high thermal conductivity and electrothermal conversion efficiency. Using graphene as a heating element can greatly improve energy utilization efficiency and achieve rapid temperature rise. The excellent conductivity of graphene allows the current to pass evenly, reducing heat loss and thus accelerating the temperature rise process.

[0054] Advantages of magnetic field treatment: Under the action of magnetic field, graphene can be oriented. This arrangement not only improves the uniformity of graphene distribution in the coating, but also enables the graphene in the coating to transfer heat more effectively. Since graphene is a two-dimensional material with extremely high thermal conductivity, the oriented graphene can form a more effective heat conduction channel, thereby improving the overall thermal conductivity of the coating; after the graphene is oriented, the thermal conductivity of the coating is significantly improved. Heat can be transferred more efficiently along the oriented arrangement direction of graphene, thereby accelerating the diffusion rate of heat and improving the deicing efficiency of the coating; the oriented arrangement of graphene can also enhance the mechanical properties of the electrothermal coating. The bonding force between graphene and the coating substrate is strengthened, making the coating more durable. At the same time, the oriented graphene can also improve the flexibility and impact resistance of the coating; the method of oriented arrangement of graphene by magnetic field treatment is highly flexible. By adjusting the intensity and direction of the magnetic field, the arrangement and direction of graphene in the electrothermal coating can be precisely controlled. This flexibility makes magnetic field treatment one of the effective means to prepare high-performance electrothermal coatings.

[0055] (b) Excellent thermal conductivity and insulation properties:

[0056] Thermal conductivity and insulation advantages of additives such as boron nitride: additives such as boron nitride have high thermal conductivity and good electrical insulation. In the present invention, additives such as boron nitride are used to heat the thermal conductive layer, which can not only effectively conduct heat and ensure that heat is evenly distributed throughout the system, but also prevent current leakage and ensure the safe operation of the equipment. This dual characteristic makes additives such as boron nitride play an irreplaceable role in heating elements.

[0057] (c) Advantages of fixed-point heating:

[0058] Advantages of epoxy resin glue: Using epoxy resin glue to glue the coating to a specific location not only ensures the stability of the coating, but also enhances the mechanical strength of the entire system. The insulating properties of epoxy resin glue help prevent current leakage and ensure the safety of the system.

[0059] Energy saving and environmental protection: Fixed-point heating technology can avoid unnecessary large-area heating, thus saving energy. In addition, the use of environmentally friendly materials and technical design helps to reduce the impact on the environment and meet the requirements of sustainable development.

[0060] Easy maintenance: The coating can be modularized to cope with different usage situations. The modular design means that damage to a single area will not affect the heating effect in other areas. This design simplifies the maintenance process because only the damaged module needs to be replaced, not the entire system, reducing maintenance costs and complexity.

[0061] The present invention innovatively combines the excellent thermal conductivity of graphene, the unique energy regulation ability of magnetic field treatment, and the stable heat resistance of additives such as boron nitride, thus creating a new technical solution that is efficient, environmentally friendly, and heats evenly. This breakthrough not only broadens the application boundaries of materials science, but also provides strong technical support and solutions for the intelligentization of household appliances, efficient industrial heating, and even precise temperature control in the aerospace field.

[0062] In the field of wind power, the present invention shows particularly significant advantages. It can effectively cope with extreme climate challenges, especially the problem of ice accumulation on wind turbine blades in severe cold and snowy weather in onshore and offshore wind power stations. Through a precise and uniform heating mechanism, the present invention can quickly and reliably melt the ice on the blades, ensuring the continuous and stable operation of the wind turbine in harsh environments, significantly improving power generation efficiency and reliability, and reducing power losses caused by downtime maintenance. This move not only reflects the environmental protection concept of green energy technology, but also directly promotes the improvement of economic benefits by reducing downtime and increasing power generation, injecting new vitality and impetus into the sustainable development of the wind power industry.

[0063] Secondly, the specific embodiments are as follows:

[0064] Example 1

[0065] The preparation process of magnetic field assisted directional heating coating is as follows:

[0066] (1) Surface cleaning of glass fiber cloth 1: glass fiber cloth 1 is taken and dust and dirt are removed from the glass fiber cloth 1 to obtain a glass fiber cloth 1 with a clean surface, and copper foil (the copper foil has a backing adhesive that can be adhered to the surface of the glass fiber cloth) is adhered to the surface of the glass fiber cloth as a conductive electrode 3; wherein the conductive electrode 4 includes two parallel and spaced main electrodes 41, each of which has a plurality of branch electrodes 42 spaced along its length direction, and the plurality of branch electrodes 42 on the two main electrodes 41 are arranged in a staggered manner, and the spacing between two adjacent branch electrodes 42 is 5 cm.

[0067] (2) Preparation of magnetic graphene:

[0068] S1: First, graphite oxide is uniformly dispersed in deionized water using ultrasonic technology to prepare a graphene oxide stock suspension with a concentration of 2 mg / ml;

[0069] S2: FeCl3·6H2O and FeCl2·4H2O in a molar ratio of 2:1 were dissolved in a hydrochloric acid solution with a concentration of 0.5 mol / L to prepare a first mixed solution with a concentration of 0.1 mg / mL;

[0070] S3: at room temperature, 1.5 L of the graphene oxide stock suspension obtained in S1 is slowly added dropwise to 1 L of the first mixed solution obtained in S2 and mixed evenly to obtain a second mixed solution;

[0071] S4: Add 1 mol / L NaOH solution to the second mixed solution obtained in S3, and adjust its pH value to 9-10. A black suspension is obtained. Heat the suspension to 60-80°C and stir for 10-30 minutes. Then, cool it to room temperature and wash it with deionized water several times until the pH value of the suspension reaches neutral, filter it, and vacuum dry it to obtain magnetic graphene;

[0072] (3) Preparation of heating thermal conductive layer 2:

[0073] Weigh the following components according to weight: 40 parts of bisphenol A epoxy resin, 25 parts of magnetic graphene, 15 parts of isophorone diamine, 1 part of sodium dodecyl sulfonate, 9 parts of boron nitride and 10 parts of water;

[0074] Add magnetic graphene, boron nitride, water and sodium dodecyl sulfate to bisphenol A epoxy resin, stir for 10 to 15 minutes to obtain a mixed slurry; then add isophorone diamine, stir for 5 to 10 minutes to obtain a heating thermal conductive coating, apply the heating thermal conductive coating to a glass fiber cloth arranged with a conductive electrode by an airless sprayer, cover the conductive electrode, and after the coating is completed, place it in a magnetic field generator, set the magnetic field strength to 0.065T, and keep it for 40 minutes. During this process, it is necessary to ensure that the heating plane is perpendicular to the magnetic field direction;

[0075] (4) After magnetization, a heating heat-conducting layer 2 is formed, which is then taken out and cured at 20 to 50° C. for 2 to 6 hours;

[0076] (5) Preparation of thermal insulation foam:

[0077] Weigh the following components according to weight: 60 parts of polyether diol, 40 parts of diphenylmethane diisocyanate, 5 parts of water, 1 part of sodium dodecylbenzene sulfonate and 1 part of triethanolamine;

[0078] During the preparation, polyether diol and diphenylmethane diisocyanate are added into a mixer, and triethanolamine and sodium dodecylbenzene sulfonate are added, and stirred for 10 to 15 minutes, and then water is added, and stirred again for 10 to 15 minutes to obtain the thermal insulation foam;

[0079] (6) After the heating thermal conductive layer 2 is cured, thermal insulation foam is sprayed on its surface to form a thermal insulation layer 3, and then cured at room temperature for 2 to 6 hours to obtain a magnetic field-assisted directional heating coating; wherein the thermal insulation layer 3 has a thickness of 10 mm, and the heating thermal conductive layer 2 has a thickness of 30 μm.

[0080] Example 2

[0081] The only difference from Example 1 is:

[0082] 1. In the preparation of magnetic graphene, the concentration of the graphene oxide stock suspension prepared in S1 is 3 mg / ml, the FeCl3·6H2O in S2 is replaced by ferroferric oxide, and the FeCl2·4H2O is replaced by manganese zinc ferrite, and the concentration of the prepared first mixed solution is 0.2 mg / mL;

[0083] 2. In the preparation of the heating and thermal conductive layer, the components and their proportions are replaced accordingly: the water-based epoxy resin is 30 parts of bisphenol A epoxy resin, 14 parts of magnetic graphene, the curing agent is 25 parts of m-phenylenediamine, the first surfactant is 1 part of sodium dodecyl sulfate, the first auxiliary agent is 10 parts of boron nitride, and the diluent is 20 parts of water;

[0084] Wherein, the thickness of the heat insulating layer is 20 mm, and the thickness of the heating heat conducting layer is 500 μm.

[0085] Example 3

[0086] The only difference from Example 1 is:

[0087] 1. In the preparation of magnetic graphene, the concentration of the graphene oxide stock suspension prepared in S1 is 2.5 mg / ml, the FeCl3·6H2O in S2 is replaced by nickel-zinc ferrite, and the FeCl2·4H2O is replaced by barium ferrite, and the concentration of the prepared first mixed solution is 0.15 mg / mL;

[0088] 2. In the preparation of the heating and thermal conductive layer, the components and their proportions are replaced accordingly: the water-based epoxy resin is 40 parts of phenolic epoxy resin, 16.8 parts of magnetic graphene, the curing agent is 7 parts of dihexyltriamine and 8 parts of isophoronediamine, the first surfactant is 2 parts of fatty alcohol polyoxyethylene ether sodium sulfate, the first auxiliary agent is 5 parts of aluminum oxide, and the diluent is 5 parts of acetone and 5 parts of styrene;

[0089] Wherein, the thickness of the heat insulating layer is 15 mm, and the thickness of the heating heat conductive layer is 200 μm.

[0090] Example 4

[0091] The only difference from Example 1 is:

[0092] 1. In the preparation of magnetic graphene, the concentration of the graphene oxide stock suspension prepared in S1 is 2.2 mg / ml, the FeCl3·6H2O and FeCl2·4H2O in S2 are replaced by FeCl3·6H2O, and the concentration of the prepared first mixed solution is 0.18 mg / mL;

[0093] 2. In the preparation of the heating and thermal conductive layer, the components and their proportions are replaced accordingly: the water-based epoxy resin is 25 parts of glycerol ether epoxy resin and 25 parts of amino epoxy resin, 12 parts of magnetic graphene, the curing agent is 10 parts of dipropylene triamine and 6.5 parts of ethylene diamine, the first surfactant is 0.7 parts of sodium dodecyl sulfonate and 0.8 parts of fatty alcohol polyoxyethylene ether, the first auxiliary agent is 3 parts of boron nitride and 3 parts of aluminum nitride, and the diluent is 14 parts of dimethylformamide;

[0094] Wherein, the thickness of the heat insulating layer is 16 mm, and the thickness of the heating heat conductive layer is 300 μm.

[0095] Example 5

[0096] The only difference from Example 1 is:

[0097] In the preparation of the heating and thermal conductive layer, the components and their proportions are replaced accordingly: the water-based epoxy resin is 30 parts of glycerol ether epoxy resin, 14 parts of magnetic graphene, the curing agent is 15 parts of dipropylene triamine, the first surfactant is 1 part of sodium dodecyl sulfate, the first auxiliary agent is 5 parts of boron nitride, and the diluent is 35 parts of water;

[0098] Wherein, the thickness of the heat insulating layer is 20 mm, and the thickness of the heating heat conductive layer is 30 μm.

[0099] Embodiment 6-8

[0100] The only difference from Example 1 is the formula of the thermal insulation layer. The specific changes in the relevant parameters are shown in the following table:

[0101]

[0102] The thermal conductivity and coating density of the magnetic field-assisted directional heating coatings prepared in Examples 1 to 8 are shown in the following table.

[0103]

[0104]

[0105] The results in the above table show that the magnetic field assisted directional heating coatings prepared in Examples 1 to 8 all have lower density and lower thermal conductivity, which indicates that the magnetic field assisted directional heating coatings prepared using different formulations have excellent performance in terms of lightweight thermal insulation.

[0106] The magnetic field-assisted directional heating coatings prepared in Examples 1 to 8 were all prepared using the following preparation method to test their electrothermal performance and deicing performance.

[0107] Epoxy resin glue is applied on the surface of the glass fiber cloth away from the heating conductive layer, and then it is pasted and fixed at the specific position that requires electric heating (for example: the inner cavity of a wind turbine blade 10m away from the tip), and then a power source is connected to the conductive electrode to heat the specific position of the electric heating (for example: heating the inner cavity of a wind turbine blade 10m away from the tip for deicing).

[0108] It should be noted that: ensure that the magnetic field assisted directional heating coating and the substrate are firmly bonded, free of bubbles, and the magnetic field assisted directional heating coating is flat.

[0109] The conditions for testing the electrothermal performance of the prepared magnetic field assisted directional heating coating are: power on at 100V and room temperature; the conditions for testing the deicing performance of the prepared magnetic field assisted directional heating coating are: power on at 100V and ambient temperature of -5 to -2°C; the test obtained the data shown in the following table.

[0110]

[0111]

[0112] Embodiment 9-13:

[0113] The main change is the magnetic field intensity in the preparation of the heating thermal conductive layer. Other raw materials and percentages are the same as in Example 1. The changes in relevant parameters are as follows:

[0114] Example No. Magnetic field strength (T) Deicing time (min) 9 0 90 10 0.05 48 11 0.075 40 12 1 57 13 5 -

[0115] The configuration methods of Examples 9-13 are the same as that of Example 1. When not treated with a magnetic field, the deicing time of the heat-generating and heat-conductive layer is relatively long. When the magnetic field strength is too large, the magnetic graphene is arranged too densely to form an effective path, and an effective circuit cannot be formed.

[0116] Embodiment 14-18:

[0117] The main change is the magnetic field treatment time in the preparation of the heating thermal conductive layer. Other raw materials and percentages are the same as in Example 1. The changes in relevant parameters are as follows:

[0118] Example No. Magnetic field strength (T) Magnetic field treatment time (h) Deicing time (min) 14 0.065 0.5 41 15 0.065 1 40 16 0.065 2 40 17 0.065 3 38 18 0.065 4 41

[0119] The configuration methods of Examples 14-18 are the same as that of Example 1. When the magnetic field strength is appropriate, the magnetic field treatment time has little effect on its deicing time.

[0120] Embodiment 19

[0121] The only difference from Example 1 is that no boron nitride is added during the preparation of the heating and heat-conducting layer.

[0122] The prepared magnetic field assisted directional heating coating was tested for its electrothermal and deicing performances: when the magnetic field assisted directional heating coating was powered at 100V and at room temperature, the surface heating rate was approximately 18°C / min; when the magnetic field assisted directional heating coating was powered at 100V and at an ambient temperature of -5 to -2°C, it took approximately 60 minutes to remove 5 to 8 cm of ice from the surface of the wind turbine blade.

[0123] Without the addition of boron nitride, a thermally conductive material, the heat generated by the heating coating cannot be quickly transferred to the surface of the wind turbine blade, making it impossible to de-ice quickly.

[0124] Embodiment 20-25:

[0125] The only difference from Example 5 is that the mass percentage of magnetic graphene in the heating thermal conductive layer is changed and the amount of change of magnetic graphene is achieved by changing the amount of water so that the total amount of each component in the heating thermal conductive layer is 100%. The adhesion strength and deicing time of the magnetic field assisted directional heating coating are then detected. The relevant parameter changes are specifically shown in the following table:

[0126] Example No. Magnetic graphene (%) Adhesion strength (MPa) Deicing time (min) 20 0 9.45 - 21 5 9.09 - 22 10 8.78 48 23 20 8.45 38 24 30 6.56 27 25 40 4.56 -

[0127] When the content of magnetic graphene in the magnetic field-assisted directional heating coating is low, the graphene particles are insufficiently distributed and cannot form a conductive network, resulting in failure of electrothermal conversion and the inability of the magnetic field-assisted directional heating coating to de-ice. If the content is too high, the graphene will occupy a large amount of space, interfere with the cross-linking of the epoxy resin, and weaken the bonding strength of the magnetic field-assisted directional heating coating. More seriously, extremely high content will significantly interfere with chemical reactions, resulting in insufficient chemical bonding, affecting the curing effect and film-forming ability, making it impossible for the magnetic field-assisted directional heating coating to form a continuous, uniform and strongly bonded film layer.

[0128] Application Examples 1-8

[0129] Based on Examples 1-8, the magnetic field assisted directional heating coatings prepared in Examples 1-8 were respectively bonded and fixed to the inner cavity of the wind turbine blade 10 m away from the tip of the wind turbine blade using epoxy resin adhesive, and the original lightning arrester was removed to ensure the smooth progress of the test.

[0130] Application Example 9

[0131] Based on Example 19, the magnetic field assisted directional heating coating prepared in Example 19 was bonded and fixed to the inner cavity of the wind turbine blade 10 m away from the tip of the wind turbine blade using epoxy resin adhesive, and the original lightning arrester was removed to ensure the smooth progress of the test.

[0132] Corresponding to use case 1 and application case 2, the test was carried out in accordance with the national standard GB-Z 25427-2010 "Lightning Protection for Wind Turbine Generator Sets". The changes in relevant parameters are shown in the following table:

[0133] Application Example No. Number of lightning strikes Heating rate after lightning strike (℃ / min) 1 0 23 2 0 20 3 0 22 4 0 20 5 0 21 6 0 23 7 0 25 8 0 24 9 4 15

[0134] Installing lightning arresters on wind turbine blades can effectively reduce the risk of being struck by lightning. However, adding heating elements inside the blades will increase the possibility of being struck by lightning, posing a threat to the stable operation of the wind turbine. To solve this problem, we adopted the method of adding insulating materials to enhance the lightning protection of the blades. Taking application example 1-2 as an example, it can be clearly observed that the use of magnetic field-assisted directional heating coatings containing insulating thermal conductive materials such as boron nitride not only significantly improves the lightning protection performance of the blades, but also improves their deicing efficiency.

[0135] In actual applications, appropriate adjustments and matching are required according to the size and scenario of the wind turbine blades to ensure that while improving comprehensive performance such as heating and deicing efficiency and lightning protection effects, long-lasting and stable protection is provided for the wind turbine blades.

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a magnetic field assisted directional heating coating, characterized in that: The following steps are involved: S1. Arrange conductive electrodes Laying a conductive electrode on a surface of the carrier; S2. Preparation of heating thermal conductive layer Adding magnetic graphene, a first auxiliary agent, a diluent and a first surfactant into a water-based epoxy resin and stirring evenly to obtain a mixed slurry; Then, a curing agent is added to the mixed slurry, and the mixture is stirred to obtain a heating thermal conductive coating, the heating thermal conductive coating is coated on the carrier and the conductive electrode is coated therebetween, and then the coating is placed in a magnetic field with a magnetic field strength of 0.05 to 0.1 T for 30 to 60 minutes, and then the coating is placed at a temperature of 20 to 50° C. for curing for 2 to 6 hours to form a heating thermal conductive layer; S3. Preparation of thermal insulation layer Coating thermal insulation foam on the surface of the heating and heat-conducting layer away from the carrier to form a thermal insulation layer, and then curing at room temperature for 2 to 6 hours; Wherein, the first auxiliary agent includes at least one of boron nitride, aluminum oxide and aluminum nitride.

2. The method for preparing a magnetic field assisted directional heating coating according to claim 1, characterized in that: The components in the heating and heat-conducting layer include, by weight, 30% to 50% of water-based epoxy resin, 10% to 30% of magnetic graphene, 15% to 25% of curing agent, 1% to 2% of a first surfactant, 5% to 15% of a first auxiliary agent, and 10% to 35% of a diluent.

3. The method for preparing a magnetic field assisted directional heating coating according to claim 1 or 2, characterized in that: The diluent includes at least one of water, acetone, styrene and dimethylformamide; and / or the waterborne epoxy resin comprises at least one of bisphenol A epoxy resin, novolac epoxy resin, glycerol ether epoxy resin and amino epoxy resin; and / or the curing agent comprises at least one of m-phenylenediamine, dihexyltriamine, isophoronediamine, dipropylenetriamine and ethylenediamine; and / or the first surfactant includes at least one of sodium dodecyl sulfate, sodium fatty alcohol polyoxyethylene ether sulfate and fatty alcohol polyoxyethylene ether; And / or the magnetic graphene includes graphene oxide and a second auxiliary agent, and the second auxiliary agent includes at least one of ferric chloride hexahydrate, ferric chloride tetrahydrate, ferrosoferric oxide, manganese zinc ferrite, nickel zinc ferrite and barium ferrite.

4. The method for preparing a magnetic field assisted directional heating coating according to claim 3, characterized in that: The preparation method of the magnetic graphene is as follows: preparing a graphene oxide stock suspension having a concentration of 2 to 3 mg / ml; FeCl3·6H2O and FeCl2·4H2O in a molar ratio of 2:1 are dissolved in a hydrochloric acid solution to prepare a first mixed solution with a concentration of 0.1 to 0.2 mg / mL; At room temperature, adding the prepared graphene oxide stock suspension dropwise to the prepared first mixed solution to form a second mixed solution; NaOH solution is added dropwise to the second mixed solution until the pH value is 9-10 to obtain a black suspension, and the black suspension is heated to 60-80° C. and stirred for 10-30 minutes; then cooled to room temperature and washed with deionized water for multiple times until the pH value of the black suspension reaches neutral, and then filtered and dried to obtain magnetic graphene.

5. The method for preparing a magnetic field assisted directional heating coating according to claim 1, characterized in that: The heat insulating layer comprises, by weight, 45 to 80 parts of a polyol compound, 40 to 60 parts of a polyisocyanate compound, 1 to 5 parts of a foaming agent, 0.1 to 1 part of a second surfactant and 1 to 5 parts of a catalyst.

6. The method for preparing a magnetic field assisted directional heating coating according to claim 5, characterized in that: The polyol compound includes at least one of a polyether diol and a polyester polyol; and / or the polyisocyanate compound comprises at least one of diphenylmethane diisocyanate and toluene diisocyanate; and / or the blowing agent comprises at least one of water, carbon dioxide blowing agent, hydrogen chloride blowing agent and ammonia blowing agent; and / or the catalyst comprises at least one of triethanolamine and triethylenediamine; And / or the second surfactant includes at least one of silicone oil, sodium dodecylbenzene sulfonate and sodium α-olefin sulfonate.

7. A magnetic field assisted directional heating coating, characterized in that: The coating is prepared by the method for preparing a magnetic field-assisted directional heating coating according to any one of claims 1 to 6.

8. An application of the magnetic field assisted directional heating coating as claimed in claim 7, characterized in that: The magnetic field assisted directional heating coating is fixed by using epoxy resin adhesive and powered on for deicing.

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