High-temperature-resistant graphene electric heating coating and preparation method thereof

Abstract

This invention provides an electrothermal structure composed of an antioxidant insulating coating, an electrothermal coating, and a substrate. The preparation method of the electrothermal structure includes first preparing a high-power-density heating coating on a substrate using a high-concentration aqueous dispersion of graphene, carbon nanotubes, an inorganic binder (low-melting-point glass), and additives; then preparing an insulating and antioxidant protective layer on the heating coating using a high-concentration aqueous dispersion of boron nitride nanosheets, an inorganic binder, and additives. The protective layer addresses the issues of easy oxidation and heat dissipation of graphene at high temperatures. An interface bridging agent optimizes the interface between the two layers, connecting graphene and boron nitride, reducing heat loss, and improving electrothermal conversion efficiency. The graphene electrothermal coating prepared by this invention can achieve safe and long-term service in high-temperature environments. The preparation process of this invention does not involve any organic solvents, is environmentally friendly, and is simple, highly operable, and suitable for industrial-scale production.

Description

Technical Field

[0001] This invention relates to a high-temperature resistant graphene electrothermal coating and its preparation method. More specifically, this invention relates to a high-temperature resistant graphene electrothermal coating, an antioxidant insulating layer, and an electrothermal / antioxidant insulating dual-coating system, and also to an electrothermal structure composed of an antioxidant insulating coating / electrothermal coating / substrate. It belongs to the field of inorganic electrothermal coatings. Background Technology

[0002] Electric heating coatings are playing an increasingly important role in building heating, industrial drying, petrochemical pipeline insulation, and aircraft de-icing due to their advantages such as being environmentally friendly, safe, and reliable. Currently, electric heating coatings typically achieve their electrothermal properties by adding conductive fillers, such as metallic or carbon-based fillers, into the coating. While metallic fillers such as gold, silver, palladium, and platinum offer excellent electrothermal performance, they are expensive; copper, iron, and aluminum are prone to oxidation, consume a lot of energy, and have a short service life; carbon-based fillers have the advantages of low specific gravity, low cost, non-toxicity, and resistance to oxidation, but their low conductivity, slow heating rate, and low electrothermal conversion efficiency limit their widespread use.

[0003] In recent years, graphene has become one of the most studied novel electrothermal fillers due to its excellent physicochemical properties. Chinese patents CN107692943A, CN 112375462 A, CN113801534A, and CN 108441066 A all use graphene as the main conductive filler, supplemented with various solvents, binders, and additives, to prepare graphene-based electrothermal pastes and their electrothermal coating devices, exhibiting good electrothermal conversion efficiency and advantages such as energy saving, environmental protection, and safety. However, most reported graphene electrothermal coatings are limited by the aging of the carrier and polymer matrix at high temperatures, making it difficult to use them for extended periods at temperatures above 300°C. This greatly limits their application in appliances such as ovens and grills, as well as in high-end fields such as industrial heating, military, and aerospace where temperature requirements are even higher. To address this issue, Chinese patent CN 109741854A uses high-temperature resistant polyimide resin and organic solvents, supplemented with conductive silver paste, to prepare a graphene electrothermal coating that can be used at 300℃ and exhibits good stability. However, it is clear that its electrothermal performance will decrease sharply as the operating temperature continues to rise. Chinese patent CN 111303763A uses organosilicon ceramic resin as a binder and adds metal powder as a conductive filler to prepare a high-temperature resistant, high-power-density graphene electrothermal coating. Although this improves its temperature resistance and power density, it is only suitable for use in environments of 200–300℃. On the other hand, graphene will undergo oxidation failure in high-temperature environments in air, which will also prevent its electrothermal coating from maintaining stable operation over a higher temperature range for extended periods. Summary of the Invention

[0004] To address the aforementioned shortcomings of existing technologies, this invention provides a high-temperature resistant graphene electrothermal coating, an antioxidant insulating layer, and an electrothermal / antioxidant insulating dual-coating system, an electrothermal structure composed of an antioxidant insulating coating / electrothermal coating / substrate, and their preparation methods.

[0005] In this application, "optional" means present or absent. "Optionally" means performed or not performed. In this application, substrate, matrix, or base material have the same meaning.

[0006] According to a first embodiment of the present invention, an aqueous high-temperature resistant graphene heating coating (or coating layer) (A) is provided, which comprises or is (mainly) composed of the following components:

[0007] (a1) 50-100 parts by weight of high-concentration graphene aqueous dispersion, preferably 60-90 parts by weight, preferably 70-80 parts by weight, for example 55, 65, 75, 85, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100 parts by weight.

[0008] (a2) Inorganic binder: 0.3-15 parts by weight, preferably 0.4-13 parts by weight, preferably 0.5-10 parts by weight, preferably 0.6-9 parts by weight, preferably 0.7-8 parts by weight, preferably 0.8-7 parts by weight, preferably 0.9-6 parts by weight, preferably 1-5 parts by weight, preferably 1.2-4.8 parts by weight, preferably 1.5-4.5 parts by weight, preferably 1.7-4.3 parts by weight, for example 2.0, 3.0 and 4.0 parts by weight;

[0009] (a3) (Optional) Conductive additive 0-15 parts by weight, preferably 0.3-15 parts by weight, preferably 0.4-13 parts by weight, preferably 0.5-12 parts by weight, preferably 0.6-10 parts by weight, preferably 0.8-9 parts by weight, preferably 0.9-8 parts by weight, preferably 1-7 parts by weight, preferably 1-6 parts by weight, 1-5 parts by weight, preferably 1.2-4.8 parts by weight, preferably 1.5-4.5 parts by weight, preferably 1.7-4.3 parts by weight, for example 2.0, 3.0 and 4.0 parts by weight;

[0010] (a4) (Optional) Thickener 0-2.2 parts by weight, 0.05-2 parts by weight, preferably 0.07-1.8 parts by weight, preferably 0.09-1.6 parts by weight, preferably 0.1-1.5 parts by weight, preferably 0.11-1.3 parts by weight, preferably 0.13-1.2 parts by weight, preferably 0.15-1.0 parts by weight, for example 0.18, 0.20, 0.30, 0.40, 0.5, 0.6, 0.7, 0.8 parts by weight; more preferably 0.1-0.5 parts by weight;

[0011] (a5) (Optional) Defoamer 0-2.2 parts by weight, 0.05-2 parts by weight, preferably 0.07-1.8 parts by weight, preferably 0.09-1.6 parts by weight, preferably 0.1-1.5 parts by weight, preferably 0.11-1.3 parts by weight, preferably 0.13-1.2 parts by weight, preferably 0.15-1.0 parts by weight, for example 0.18, 0.20, 0.30, 0.40, 0.5, 0.6, 0.7, 0.8 parts by weight; more preferably 0.1-0.5 parts by weight;

[0012] (a6) (Optional) Leveling agent 0-2.2 parts by weight, 0.05-2 parts by weight, preferably 0.07-1.8 parts by weight, preferably 0.09-1.6 parts by weight, preferably 0.1-1.5 parts by weight, preferably 0.11-1.3 parts by weight, preferably 0.13-1.2 parts by weight, preferably 0.15-1.0 parts by weight, for example 0.18, 0.20, 0.30, 0.40, 0.5, 0.6, 0.7, 0.8 parts by weight; more preferably 0.1-0.5 parts by weight.

[0013] Preferably, the sum of the masses of components (a1)-(a6) is 85-100 wt% of the total mass of the high-temperature resistant graphene heating coating (or coating) (A), preferably 87-100 wt%, preferably 88-100 wt%, preferably 90-100 wt%, preferably 92-100 wt%, preferably 94-100 wt%, preferably 95-100 wt%, preferably 96-100 wt%, preferably 97-100 wt%, preferably 98-100 wt%, preferably 99-100 wt%, for example 99.5% or 99.8% wt%.

[0014] The high-concentration graphene aqueous dispersion (or simply aqueous dispersion) (a1) comprises or is mainly composed of the following components: (I) graphene; (II) polymeric dispersant and (III) water (preferably deionized water).

[0015] Preferably, the concentration of graphene (I) in the aqueous dispersion (a1) is 18-250 mg / mL, more preferably 19-220 mg / mL, more preferably 20-200 mg / mL, more preferably 30-180 mg / mL, more preferably 40-170 mg / mL, more preferably 50-160 mg / mL, for example 60, 70, 80, 90, 100, 110, 120, 130, 140, 150 mg / mL.

[0016] The particle size (average particle size or sheet diameter) of graphene is generally in the range of 0.4-15 μm, preferably 0.5-13 μm, more preferably 0.7-10 μm, and even more preferably 1-9 μm, such as 2, 3, 4, 5, 6, 7 or 8 μm.

[0017] Preferably, the polymeric dispersant (II) is selected from one or more of polyvinylpyrrolidone, polyethyleneimine, polyacrylamide, soluble starch, nanocellulose, polydiallyldimethylammonium chloride and / or sericin.

[0018] Preferably, in the high-concentration graphene aqueous dispersion (a1), the mass ratio of graphene to polymeric dispersant is 0.2-5:1 (i.e., (0.2-5):1, by wt), preferably 0.25-4:1, preferably 0.3-3:1, preferably 0.35-2.8:1, preferably 0.4-2.5:1, preferably 0.45-2:1, for example 0.5:1, 0.7:1, 0.8:1, 1:1, 1.2:1, 1.5:1, 1.8:1, 2.6:1, 2.8:1, 3.3:1, 3.7:1.

[0019] Preferably, the sum of the masses of the graphene (I), polymeric dispersant (II), and water (III) components is 85-100 wt%, preferably 87-100 wt%, preferably 88-100 wt%, preferably 90-100 wt%, preferably 92-100 wt%, preferably 94-100 wt%, preferably 95-100 wt%, preferably 96-100 wt%, preferably 97-100 wt%, preferably 98-100 wt%, preferably 99-100 wt%, for example 99.5% or 99.8% wt%.

[0020] Preferably, the inorganic binder (a2) is glass powder with a low melting point. Its melting point is generally in the range of 350-1200℃, preferably 370-1150℃, preferably 390-1100℃, preferably 400-1000℃, preferably 430-980℃, preferably 430-980℃, for example 500, 550, 600, 620, 630, 640, 650, 700, 750, 800, 850℃.

[0021] Preferably, the relative amounts of (a1) and (a2) should be such that the mass ratio of graphene to inorganic binder (e.g., glass powder) is generally in the range of 0.4-5:1, preferably in the range of 0.5-4:1, more preferably in the range of 0.6-3:1, and even more preferably in the range of 1-2:1, such as 4.5:1, 3.5:1, or 2.5:1.

[0022] The low-melting-point glass (powder) is, for example, a SiO2-B2O3-based low-melting-point glass powder, such as borosilicate glass, which is composed of 20-60 wt% SiO2, 5-30 wt% B2O3, 3-25 wt% ZnO, 0.5-10 wt% CaO, 0.5-7 wt% MgO, 0.5-5 wt% BaO, 5-20 wt% Na2O, 5-20 wt% K2O, and 0.1-2 wt% Al2O3; or, for example, a bismuth-phosphorus-based lead-free low-melting-point glass powder, such as P2O5 10-80 wt%, Bi2O3 10-60 wt%, ZnO 0-8 wt%, Sb2O3 0-5 wt%, SnO2 0-5 wt%, Al2O3 0-4 wt%, Li2O+Na2O+K2O 0-10 wt%, Ag2O Composition: 0-5 wt%.

[0023] The particle size or mesh number of low melting point glass powder is generally 800-2500 mesh, preferably 1000-2300 mesh, preferably 1200-2100 mesh, preferably 1500-2000 mesh, and preferably 1600-1900 mesh.

[0024] The conductive additive (a3) ​​is selected from one or more of carbon nanotubes (i.e., single-walled carbon nanotubes, double-walled carbon nanotubes, and / or multi-walled carbon nanotubes), metal powders, and polyacetylene (powder). Specifically, the conductive additive is selected from one or more of single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, metal powders (e.g., copper powder, iron powder, silver powder, zinc powder, and / or aluminum powder), and polyacetylene (powder).

[0025] More preferably, considering the significant improvement in the gloss (or smoothness) or flatness of the coating, the conductive additive (a3) ​​is selected from one or more (i.e., three) of single-walled carbon nanotubes, double-walled carbon nanotubes, and / or multi-walled carbon nanotubes. That is, the conductive additive is single-walled carbon nanotubes, double-walled carbon nanotubes, and / or multi-walled carbon nanotubes.

[0026] Preferably, the relative amounts of (a1) and (a3) ​​should be such that the mass ratio of graphene to conductive additives (e.g., carbon nanotubes) is generally in the range of 0.4-5:1, preferably in the range of 0.5-4:1, more preferably in the range of 0.6-3:1, and even more preferably in the range of 1-2:1, such as 4.5:1, 3.5:1, and 2.5:1.

[0027] The thickener (a4) is selected from one, two, or more of the following: methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxymethylhydroxyethylcellulose, hydroxymethylhydroxypropylcellulose, hydroxyethylhydroxypropylcellulose, hydroxypropylmethylcellulose, sodium carboxymethylcellulose, gum arabic, xanthan gum, sodium alginate, and polyethylene oxide. These are all water-soluble. Non-water-soluble cellulose derivatives, such as ethylcellulose, cannot be used as thickeners.

[0028] The defoamer (a5) is one or more of the following: silicone defoamer, fatty alcohol defoamer, and polyether defoamer.

[0029] The leveling agent (a6) is one or more of (poly)acrylic leveling agents and silicone leveling agents.

[0030] In this application, through the synergistic effect of thickener, defoamer and leveling agent, an electrothermal coating (A) with high gloss and highly smooth surface can be obtained.

[0031] In this invention, the method for preparing a high-temperature resistant graphene heating coating (or coating layer) (A) includes mixing or blending components (a1)-(a6) by grinding. The blending method for the components of the heating slurry is grinding, which includes either ball milling or sand milling, with a rotation speed of 100-5000 rpm, preferably 400-4000 rpm, preferably 800-4000 rpm, and a grinding time of 1-12 hours, preferably 3-10 hours, preferably 5-8 hours.

[0032] The viscosity (kinetic viscosity at 25°C, centipoise) of the high-temperature resistant graphene heating coating (A) is 15-700 centipoise, preferably 17-500 centipoise, preferably 18-400 centipoise, preferably 20-200 centipoise, preferably 25-150 centipoise, and preferably 30-60 centipoise.

[0033] According to a second embodiment of the present invention, the present invention also provides an aqueous antioxidant insulating coating (coating) (B). It is coated on or located on the above-mentioned high-temperature resistant graphene heating coating (or coating) (A).

[0034] The water-based antioxidant insulating coating (coating) (B) comprises or is (mainly) composed of the following components:

[0035] (b1) 50-100 parts by weight of high-concentration boron nitride nanosheet aqueous dispersion, preferably 60-90 parts by weight, preferably 70-80 parts by weight, for example 55, 65, 75, 85, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100 parts by weight;

[0036] (b2) Inorganic binder: 0.3-15 parts by weight, preferably 0.4-13 parts by weight, preferably 0.5-10 parts by weight, preferably 0.6-9 parts by weight, preferably 0.7-8 parts by weight, preferably 0.8-7 parts by weight, preferably 0.9-6 parts by weight, preferably 1-5 parts by weight, preferably 1.2-4.8 parts by weight, preferably 1.5-4.5 parts by weight, preferably 1.7-4.3 parts by weight, for example 2.0, 3.0 and 4.0 parts by weight;

[0037] (b3) (Optional) Interface bridging agent 0-5 parts by weight, preferably 0.1-5 parts by weight, preferably 0.2-4.5 parts by weight, preferably 0.3-4 parts by weight, preferably 0.35-3.5 parts by weight, preferably 0.4-3.0 parts by weight, preferably 0.45-2.5 parts by weight, preferably 0.5-2.0 parts by weight, preferably 0.7-1.7 parts by weight, preferably 1.0-1.5 parts by weight;

[0038] (b4) (Optional) Thickener: 0-2.2 parts by weight, 0.05-2 parts by weight, preferably 0.07-1.8 parts by weight, preferably 0.09-1.6 parts by weight, preferably 0.1-1.5 parts by weight, preferably 0.11-1.3 parts by weight, preferably 0.13-1.2 parts by weight, preferably 0.15-1.0 parts by weight, for example 0.18, 0.20, 0.30, 0.40, 0.5, 0.6, 0.7, 0.8 parts by weight; more preferably 0.1-0.5 parts by weight;

[0039] (b5) (Optional) Defoamer 0-2.2 parts by weight, 0.05-2 parts by weight, preferably 0.07-1.8 parts by weight, preferably 0.09-1.6 parts by weight, preferably 0.1-1.5 parts by weight, preferably 0.11-1.3 parts by weight, preferably 0.13-1.2 parts by weight, preferably 0.15-1.0 parts by weight, for example 0.18, 0.20, 0.30, 0.40, 0.5, 0.6, 0.7, 0.8 parts by weight; more preferably 0.1-0.5 parts by weight;

[0040] (b6) (Optional) Leveling agent 0-2.2 parts by weight, 0.05-2 parts by weight, preferably 0.07-1.8 parts by weight, preferably 0.09-1.6 parts by weight, preferably 0.1-1.5 parts by weight, preferably 0.11-1.3 parts by weight, preferably 0.13-1.2 parts by weight, preferably 0.15-1.0 parts by weight, for example 0.18, 0.20, 0.30, 0.40, 0.5, 0.6, 0.7, 0.8 parts by weight; more preferably 0.1-0.5 parts by weight.

[0041] In order to ensure that boron nitride nanosheets are arranged regularly and orderly in the coating (e.g., arranged regularly, densely and orderly like fish scales, overlapping or bridging), so as to further improve the coating's anti-oxidation and insulation properties, the use of the above-mentioned interface bridging agent is preferred.

[0042] The aforementioned antioxidant insulating coating or coating (B) is applied to or located on the aforementioned high-temperature resistant graphene heating coating (A).

[0043] In this application, (a2) and (b2) may be the same or different, (a4) and (b4) may be the same or different, (a5) and (b5) may be the same or different, or (a6) and (b6) may be the same or different. That is, (a2) and (b2), (a4) and (b4), (a5) and (b5), and (a6) and (b6) may be made of the same or different materials or substances.

[0044] Preferably, the sum of the masses of components (b1)-(b6) is 85-100 wt% of the total mass of the antioxidant insulating coating (coating) (B), preferably 87-100 wt%, preferably 88-100 wt%, preferably 90-100 wt%, preferably 92-100 wt%, preferably 94-100 wt%, preferably 95-100 wt%, preferably 96-100 wt%, preferably 97-100 wt%, preferably 98-100 wt%, preferably 99-100 wt%, for example 99.5% or 99.8% wt%.

[0045] The high-concentration boron nitride nanosheet aqueous dispersion (or simply boron nitride nanosheet aqueous dispersion) (b1) comprises or is mainly composed of the following components: (1) boron nitride nanosheets; (2) polymeric dispersant and (3) water (preferably deionized water).

[0046] Preferably, in the high-concentration boron nitride nanosheet aqueous dispersion (b1), the concentration of boron nitride nanosheets (1) is 25-300 mg / mL, more preferably 30-280 mg / mL, more preferably 35-270 mg / mL, more preferably 40-250 mg / mL, more preferably 45-230 mg / mL, more preferably 50-200 mg / mL, more preferably 55-180 mg / mL, more preferably 60-170 mg / mL, more preferably 65-160 mg / mL, for example 70, 80, 90, 100, 110, 120, 130, 140, 150 mg / mL.

[0047] The particle size (average particle size or sheet diameter) of the boron nitride nanosheets (1) is generally in the range of 10-500 nm, preferably 12-450 nm, preferably 15-420 nm, preferably 18-400 nm, preferably 20-370 nm, preferably 25-350 nm, preferably 30-300 nm, preferably 35-250 nm, preferably 40-200 nm, for example 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 160, 170, 180 or 190 nm.

[0048] Preferably, the polymeric dispersant (2) is selected from one or more of polyvinylpyrrolidone, polyethyleneimine, polyacrylamide, soluble starch, nanocellulose, and / or sericin. The polymeric dispersant (2) may be the same as or different from the polymeric dispersant (II) described above. That is, both may be selected from the same or different materials or substances.

[0049] In the high-concentration boron nitride nanosheet aqueous dispersion (b1), the mass ratio of boron nitride nanosheets to polymeric dispersant is 0.2-5:1 (i.e., (0.2-5):1, by wt), preferably 0.25-4:1, preferably 0.3-3:1, preferably 0.35-2.8:1, preferably 0.4-2.5:1, preferably 0.45-2:1, for example 0.5:1, 0.7:1, 0.8:1, 1:1, 1.2:1, 1.5:1, 1.8:1, 2.6:1, 2.8:1, 3.3:1, 3.7:1.

[0050] Preferably, the sum of the masses of the above boron nitride nanosheets (1), polymeric dispersant (2), and water (3) is 85-100 wt%, preferably 87-100 wt%, preferably 88-100 wt%, preferably 90-100 wt%, preferably 92-100 wt%, preferably 94-100 wt%, preferably 95-100 wt%, preferably 96-100 wt%, preferably 97-100 wt%, preferably 98-100 wt%, preferably 99-100 wt%, for example 99.5% or 99.8% wt%.

[0051] The inorganic binder (b2) and the inorganic binder (a2) may be the same or different. That is, they can be made of the same or different materials or substances. Preferably, they are the same, and the inorganic binder (b2) is a glass powder with a low melting point, which is generally in the range of 350-1200°C.

[0052] Preferably, the relative amounts of (b1) and (b2) should be such that the mass ratio of boron nitride nanosheets to inorganic binder (e.g., glass powder) is generally in the range of 0.4-5:1, preferably in the range of 0.5-4:1, more preferably in the range of 0.6-3:1, and even more preferably in the range of 1-2:1, such as 4.5:1, 3.5:1, and 2.5:1.

[0053] The interface bridging agent (b3) is an interface bridging agent containing aromatic ring groups (e.g., benzene ring or naphthalene ring) and / or heteroaromatic ring groups (e.g., pyridine ring or isofluoroazine ring). Preferably, the interface bridging agent (b3) is an interface bridging agent containing aromatic ring groups (e.g., benzene ring or naphthalene ring) and / or heteroaromatic ring groups (e.g., pyridine ring or isofluoroazine ring) and polar groups (e.g., anionic groups, such as sulfonate, phosphate, and / or carboxylate; cationic groups, such as quaternary ammonium salt groups; nonionic polar groups, such as hydroxyl or amino groups), preferably selected from one or more of sodium lignosulfonate, sodium riboflavin phosphate, and sodium methylene bisnaphthalene sulfonate.

[0054] Preferably, the relative amounts of (b1) and (b3) should be such that the mass ratio of boron nitride nanosheets to the interfacial bridging agent is generally in the range of 0.4-5:1, preferably in the range of 0.5-4:1, more preferably in the range of 0.6-3:1, and even more preferably in the range of 1-2:1, such as 4.5:1, 3.5:1, and 2.5:1.

[0055] Thickener (b4) and thickener (a4) may be the same or different. That is, they can both be selected from the same or different materials or substances. Preferably, they are the same.

[0056] Defoamer (b5) and defoamer (a5) may be the same or different. That is, they can both be made of the same or different materials or substances. Preferably, they are the same.

[0057] The leveling agent (b6) and the leveling agent (a6) may be the same or different. That is, they can both be made of the same or different materials or substances. Preferably, they are the same.

[0058] In this application, through the synergistic effect of thickener, defoamer and leveling agent, an antioxidant insulating coating (B) with high gloss and highly smooth surface can be obtained.

[0059] In this invention, the method for preparing the antioxidant insulating coating (or coating layer) (B) includes mixing or blending components (b1)-(b6) by grinding. The blending method of the components of the heating slurry is grinding, which includes either ball milling or sand milling, with a rotation speed of 100-5000 rpm, preferably 400-4000 rpm, preferably 800-4000 rpm, and a grinding time of 1-12 hours, preferably 3-10 hours, preferably 5-8 hours.

[0060] The viscosity (kinetic viscosity at 25°C, centipoise) of the antioxidant insulating coating (B) is 15-700 centipoise, preferably 17-500 centipoise, preferably 18-400 centipoise, preferably 20-200 centipoise, preferably 25-150 centipoise, and preferably 30-60 centipoise.

[0061] Generally, the high-temperature resistant graphene heating coating (A) is formed by the following process:

[0062] The components (a1), (a2), (a3), (a4), (a5), and (a6) are ground to obtain a high-temperature resistant graphene heating coating (A). The high-temperature resistant graphene heating coating (A) (i.e., heating paste) is then coated onto a substrate to form a heating layer.

[0063] Generally, the antioxidant insulating coating (B) is formed by the following process:

[0064] The components (b1), (b2), (b3), (b4), (b5), and (b6) are ground to obtain an antioxidant insulating coating (B), which is then coated onto a heating layer (e.g., a high-temperature resistant graphene heating coating (A)) to form an antioxidant insulating coating.

[0065] According to a third embodiment of the present invention, the present invention provides a dual coating system (AB) for heating and insulation, the coating system (AB) comprising the above-described waterborne high-temperature resistant graphene heating coating (A) and the above-described waterborne antioxidant insulating coating (B), or the system (AB) is composed of the above-described waterborne coating (A) and the above-described waterborne coating (B).

[0066] Generally, paint (A) and paint (B) are packaged in their own containers. That is, paint (A) is packaged in a separate container. Paint (B) is also packaged in a separate container.

[0067] According to a fourth embodiment of the present invention, the present invention also provides a graphene electrothermal structure (AB) or an electrothermal / antioxidant insulating dual-coating system (AB), that is, the present invention provides an electrothermal structure composed of an antioxidant insulating coating / electrothermal coating / substrate. The system or structure comprises: a substrate; the aforementioned high-temperature resistant graphene electrothermal coating (A) on the substrate (surface); and the aforementioned antioxidant insulating coating (B) on the surface of the electrothermal coating (A).

[0068] Preferably, the substrate can be microcrystalline glass, ceramic, quartz glass, metal plate or alloy plate with ceramic insulation layer (e.g. aluminum alloy or titanium alloy plate, such as the fuselage or wing of an aircraft, the outer shell of a spacecraft), etc.

[0069] The aforementioned high-temperature resistant graphene electrothermal coating (A) is formed by coating and optionally drying the aforementioned high-temperature resistant graphene electrothermal coating (A). The electrothermal coating (A) includes a wet coating or a dry coating.

[0070] The aforementioned antioxidant insulating coating (B) is formed by coating and optionally drying the aforementioned antioxidant insulating paint (B). Preferably, the aforementioned antioxidant insulating coating (B) is formed by coating, (multi-stage) heating, melting, and cooling the aforementioned antioxidant insulating paint (B). Multi-stage heating refers to a heating method employing gradually increasing heating temperatures in multiple stages.

[0071] Generally, the thickness of the high-temperature resistant graphene electrothermal coating (A) is 15μm to 2mm, preferably 20μm to 1.5mm, more preferably 30μm to 1mm, more preferably 40 to 800μm, more preferably 50μm to 500μm, and even more preferably 60 to 300μm, for example 80, 100, 150, 200, 250, 350, 400, 450, 550, 600, 700, 750, and 900μm.

[0072] The thickness of the antioxidant insulating coating (B) depends on the upper limit of the applicable voltage range of the electrothermal coating (e.g., 110V, 220V, or 380V). The thickness is generally 5-4000 μm, preferably 8-3800 μm, preferably 10-3500 μm, preferably 12-3000 μm, preferably 20-2000 μm, preferably 25-1500 μm, preferably 28-1200 μm, and preferably 30-300 μm. Examples include 35, 50, 80, 100, 150, 200, 300, 400, 500, 600, 700, 800, 900, 1000, or 1100 μm.

[0073] The present invention also provides a method for preparing a high-temperature resistant graphene heating coating (A), comprising the following steps:

[0074] The components (a1), (a2), (a3), (a4), (a5), and (a6) are ground to obtain a high-temperature resistant graphene heating coating (A). The high-temperature resistant graphene heating coating (A) (i.e., heating paste) is then coated onto a substrate to form a heating layer.

[0075] The present invention also provides a method for preparing an antioxidant insulating coating (B), comprising the following steps:

[0076] The components (b1), (b2), (b3), (b4), (b5), and (b6) are ground to obtain an antioxidant insulating coating (B), which is then coated onto a heating layer (e.g., a high-temperature resistant graphene heating coating (A)) to form an antioxidant insulating coating.

[0077] According to a fifth embodiment of the present invention, the present invention also provides a method for preparing an electrothermal / antioxidant insulating dual-coating system (AB), or a method for preparing an electrothermal structure composed of an antioxidant insulating coating / electrothermal coating / substrate, the method comprising:

[0078] 1) A high-temperature resistant graphene heating coating (A) (i.e., heating paste) is coated onto a substrate to form a heating layer, optionally followed by drying; and

[0079] 2) An antioxidant insulating coating (B) is applied to the surface of a high-temperature graphene heating coating (A) to form an antioxidant insulating coating, thereby forming a double coating system (AB) on the substrate.

[0080] That is, the present invention also provides a graphene electrically heated structure (AB), the structure comprising:

[0081] Substrate;

[0082] A high-temperature resistant graphene electrothermal coating (A) formed on a substrate by a high-temperature resistant graphene heating coating (A); and

[0083] An antioxidant insulating coating (B) is formed on the surface of the electrothermal coating (A) by an antioxidant insulating coating (B).

[0084] Generally, one of the following methods can be chosen as the coating method: spraying, scraping, or screen printing.

[0085] Preferably, the substrate can be microcrystalline glass, ceramic, quartz glass, metal plate or alloy plate with ceramic insulation layer (e.g. aluminum alloy or titanium alloy plate, such as the fuselage or wing of an aircraft, the outer shell of a spacecraft), etc.

[0086] Preferably, the preparation method of the dual-coating system (AB) or the graphene electrothermal structure (AB) further includes:

[0087] 3) Heat the double-coating system (AB) applied to the substrate in step 2) to the first stage and heat it for 5-10 minutes under heat preservation to remove moisture.

[0088] Specifically, the temperature in the first stage is 100–200℃.

[0089] Preferably, the preparation method of the dual-coating system (AB) or the graphene electrothermal structure (AB) further includes:

[0090] 4) Heat the double-coated system (AB) after the heat treatment in step 3) to the second stage and heat it for 5 to 10 minutes under heat preservation to remove organic components.

[0091] Specifically, the temperature in the second stage is 350–550℃.

[0092] Preferably, the preparation method of the dual-coating system (AB) or the graphene electrothermal structure (AB) further includes:

[0093] 5) Heat the double-coated system (AB) after heat treatment in step 4) to the third stage and heat it for 5-10 minutes under heat preservation for welding of inorganic binder.

[0094] Specifically, the temperature in the third stage is 600–1200℃.

[0095] Preferably, the preparation method of the dual-coating system (AB) or the graphene electrothermal structure (AB) further includes:

[0096] 6) Cool the double-coated system (AB) after heat treatment in step 5) (e.g., cool to room temperature) to allow the coating to cure. That is, cooling to room temperature completes the preparation of the high-temperature resistant electrothermal coating.

[0097] In this invention, the coating preparation process (preferably, each step) is carried out in an atmosphere of air or an inert gas (e.g., nitrogen, argon, or helium).

[0098] Multi-stage heating and warming promotes the formation of a dense coating, prevents the formation of microbubbles within the coating, and improves the coating's performance.

[0099] In this invention, the thickness of the graphene electrothermal coating (A) is preferably 15 μm to 2 mm, more preferably 20 μm to 1.5 mm, more preferably 30 μm to 1 mm, more preferably 40 to 800 μm, more preferably 50 μm to 500 μm, and even more preferably 60 to 300 μm, for example 80, 100, 150, 200, 250, 350, 400, 450, 550, 600, 700, 750, or 900 μm. Preferably, the thickness of the electrothermal coating (A) is 30 μm to 1 mm, more preferably 40 to 800 μm, more preferably 50 μm to 500 μm, and even more preferably 60 to 300 μm, for example 80, 100, 150, 200, or 250 μm.

[0100] The thickness of the antioxidant insulating coating (B) is 5-4000 μm, preferably 8-3800 μm, preferably 10-3500 μm, preferably 12-3000 μm, preferably 20-2000 μm, preferably 25-1500 μm, preferably 28-1200 μm, preferably 30-300 μm. For example, 35, 50, 80, 100, 150, 200, 300, 400, 500, 600, 700, 800, 900, 1000, or 1100 μm. Preferably, the thickness of the insulating coating (B) is 20-3000 μm, more preferably 30-100 μm.

[0101] In this invention, the electrothermal coating generates heat simply by applying a voltage, typically 5–380V, 5–220V, or 5–110V, for example, 7, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100V.

[0102] To address the shortcomings of existing graphene electrothermal coatings in withstanding high-temperature applications, this invention proposes a novel technical solution. This solution enables long-term service of graphene electrothermal coatings in high-temperature environments, potentially expanding its applications to more fields. It also solves the problem of graphene's susceptibility to oxidation and poor electrothermal performance stability at high temperatures (above 600°C). Furthermore, it provides an effective way to replace traditional resistance wires with graphene electrothermal coatings in high-temperature heating environments. Simultaneously, this invention uses an interface bridging agent to optimize the interface between the heating layer and the anti-oxidation insulating layer. By effectively connecting graphene and boron nitride, and ensuring that boron nitride nanosheets are arranged regularly and orderly within the coating (e.g., arranged, overlapped, or bridged like fish scales), this further improves the coating's anti-oxidation and insulation properties, particularly reducing heat loss and increasing electrothermal conversion efficiency and power density.

[0103] Advantages of the present invention

[0104] 1. This invention does not involve any organic solvents in the preparation process, making it green and environmentally friendly. Moreover, the process is simple and highly operable, enabling the large-scale, green, and low-cost preparation of graphene electrothermal coatings, which is suitable for industrial production.

[0105] 2. This invention can achieve high-concentration uniform dispersion of graphene / carbon nanotubes in aqueous slurry (sand milling or ball milling), which is beneficial to exert the synergistic effect of one-dimensional and two-dimensional conductive fillers under the action of inorganic binders, and construct an efficient conductive network, thereby achieving the performance of low energy consumption, fast heating and high electrothermal conversion efficiency of graphene electrothermal coating.

[0106] 3. The interface bridging agents used in this invention (sodium lignosulfonate, sodium riboflavin phosphate, sodium methylene bisnaphthalene sulfonate) contain benzene ring structures or aromatic heterocyclic structures in their molecular structures, which can form π-π (π-π) interactions with graphene. Preferably, the molecular structure also contains polar groups (e.g., phosphate, sulfonate, carboxylic acid, hydroxyl, or amino groups), which can form hydrogen bonds with the hydroxyl groups on the surface of boron nitride nanosheets. These interactions can effectively connect the graphene and boron nitride two-dimensional materials at the interface, enabling their self-assembly at the interface, thereby effectively reducing the thermal resistance at the interface and improving the overall electrothermal conversion efficiency and power density of the electrothermal coating. The interface bridging agent optimizes the two-layer interface, connecting graphene and boron nitride, thereby reducing the heat loss of the electrothermal coating.

[0107] 4. This invention uses an organic-inorganic dual binder. The organic binder plays an adhesion role in the coating stage, and the inorganic binder plays a welding role in the curing stage. The organic and inorganic binders play their roles in stages, making it suitable for various substrates such as microcrystalline glass, ceramics, and quartz glass.

[0108] 5. By using an inorganic binder and an antioxidant insulating layer, this invention overcomes the problem of easy oxidation of existing graphene coatings at high temperatures, improves the weather resistance of the coating, and enables the graphene electrothermal coating to serve for a long time at high temperatures (greater than 500°C).

[0109] 6. This invention, by combining a graphene heating coating and an antioxidant insulating coating, can avoid direct contact between the heating layer and the heated object, improve the stability of the coating, make the heating surface more uniform, and achieve safe and efficient heat generation. Attached Figure Description

[0110] Figure 1 This is a scanning electron microscope (SEM) image (apparent SEM image) of the graphene electrothermal layer of Example 1.

[0111] Figure 2 This is a schematic diagram of the structure of the high-temperature resistant graphene electrothermal coating prepared by the present invention.

[0112] Figure 3 These are the electrothermal conversion curves of the graphene electrothermal coating in Example 1 under different safe voltages (10-20V).

[0113] Figure 4 This is the heating curve (500°C) of the graphene electrothermal coating of Example 1 at 25V.

[0114] Figure 5 This is an infrared thermal imaging scan image of the graphene electrothermal coating of Example 1 when heated at 25V. Detailed Implementation

[0115] The present invention will be further described in detail through the following embodiments, but the present invention is not limited to these embodiments.

[0116] The devices used in the embodiments are all commonly used in the art and commercially available, unless otherwise specified.

[0117] Raw materials used in the examples:

[0118] Lignin is a high molecular weight polymer with a three-dimensional network structure of polyphenols, which is composed of three basic structural units: guaiacol, syringyl, and p-hydroxyphenylpropane, linked by C-C bonds, CO-C bonds, etc.

[0119] The existing method for synthesizing sodium lignosulfonate is shown below:

[0120]

[0121] Commercially available sodium lignosulfonate can be used in the examples.

[0122] The graphene used in the embodiments of this application was prepared according to the method of Example 1 in the published patent CN110015655A, and the sheet diameter was in the range of 1-5 μm.

[0123] The boron nitride nanosheets used in the embodiments of this application were prepared in-house. The specific preparation method is as follows: 5 grams of polyvinylpyrrolidone (K30, Sinopharm Chemical Reagent Co., Ltd.) were dissolved in 25 ml of deionized water under stirring. After complete dissolution, the solution and 5 grams of powdered boron nitride (sheet diameter: 1 μm, Aladdin reagent) were added to a ball mill jar. After adding milling beads, the mixture was ball-milled at 300 rpm for 20 h to obtain a viscous slurry. The viscous slurry was then diluted with 480 ml of deionized water and stirred for 30 minutes to obtain a boron nitride nanosheet dispersion. Finally, the dispersion was freeze-dried to obtain polyvinylpyrrolidone-modified boron nitride nanosheet powder. The obtained powder was annealed at 700 °C in a nitrogen atmosphere for 1 hour to obtain pure boron nitride nanosheet powder. The heating rate during annealing was 10 °C / min, and the initial temperature was room temperature. After annealing, the sample was naturally cooled in a nitrogen atmosphere.

[0124] The low melting point glass powder used in the examples was purchased from Anmi Micro-Nano New Materials (Guangzhou) Co., Ltd., and its grade is GT series glass powder.

[0125] Example 1 (Preferred)

[0126] Preparation of graphene heating slurry: 30g of an aqueous dispersion with a graphene concentration of 50mg / ml was selected, wherein the graphene (sheet diameter 1-5μm) in the dispersion was mixed with polyvinylpyrrolidone (number average molecular weight 30000). (Sinopharm Chemical Reagent Co., Ltd., brand: K30); The mass ratio of the two components was 1:1. 0.75g of carbon nanotube powder (Zhongzhe Carbon Nanomaterials Technology Co., Ltd., length: 5-10μm, multi-walled carbon nanotubes), 0.75g of low-melting-point glass powder (total melting temperature 650℃, manufacturer: Anmi Micro-Nano, GT series glass powder), 0.03g of thickener methylcellulose (Sinopharm Group, brand: M15), 0.03g of silicone defoamer (Datian Chemical, brand: TCB-1), and 0.03g of silicone leveling agent (Qianyou Chemical, brand: AKN-1032) were added to a 50ml ball mill jar. The mixture was ball-milled at 500 rpm for 4 hours to obtain a uniformly dispersed graphene heating slurry (A1) with a viscosity (25℃, centipoise) of 45 centipoise.

[0127] Preparation of Antioxidant Insulating Coating (Antioxidant Insulating Layer Paste): 30g of an aqueous dispersion of boron nitride nanosheets with a concentration of 50mg / ml was selected, wherein the mass ratio of boron nitride nanosheets (self-made) to polyvinylpyrrolidone (number average molecular weight 30000, Sinopharm Group, brand: K30) in the dispersion was 1:1. 0.75g of sodium methylene bis(naphthalene) sulfonate (Keward Chemical, brand: NNO), 1.5g of low-melting-point glass powder (total melting temperature 650℃, manufacturer: Anmi Micro-Nano New Materials, GT series glass powder), 0.05g of methylcellulose (Sinopharm Group, brand: M15), 0.03g of silicone defoamer (manufacturer: Datian Chemical, brand: TCB-1), and 0.03g of silicone leveling agent (manufacturer: Qianyou Chemical, brand: AKN-1032) were added to a 50ml ball mill jar. The mixed slurry was ball-milled at 500 rpm for 4 hours to obtain a uniformly dispersed antioxidant insulating slurry (B1) with a viscosity of 60 centipoise.

[0128] The sodium methylene bisnaphthalene sulfonate has the following structure:

[0129]

[0130] Preparation of High-Temperature Resistant Graphene Electrothermal Coating: First, graphene heating slurry was coated onto a ceramic sheet using a scraping method. After 10 minutes, an antioxidant insulating layer slurry was then coated onto the surface of the heating coating using the same scraping method to ensure uniform coverage. After 10 minutes, the coated ceramic sheet was placed in a muffle furnace for curing and sintering. The heating program was set as follows: heating rate 10℃ / min, heating to 150℃, holding for 10 minutes, continuing to heat to 480℃, holding for 10 minutes, continuing to heat to 650℃, holding for 10 minutes, and then stopping heating to allow for natural cooling. After returning to room temperature, tests showed that under 25V voltage, the heating coating rapidly (approximately 3 minutes) heated to 500℃, an increase of 475℃ compared to before applying any voltage, with uniform temperature on the heating surface and good coating stability.

[0131] The thickness of the graphene electrothermal coating is approximately 40 μm. The thickness of the antioxidant insulating coating is approximately 30 μm.

[0132] Product performance is shown in Table 1 below.

[0133] Reference Example 1

[0134] Repeat Example 1, except without using sodium methylene bis(naphthalene) sulfonate.

[0135] The thickness of the graphene electrothermal coating is approximately 40 μm. The thickness of the antioxidant insulating coating is approximately 30 μm.

[0136] Product performance is shown in Table 1 below.

[0137] Example 2 (Preferred)

[0138] Preparation of graphene heating slurry: 30g of an aqueous dispersion of graphene with a concentration of 50mg / ml was selected, wherein the mass ratio of graphene to polyethyleneimine (number average molecular weight: 600, manufacturer: Aladdin) in the dispersion was 1:1. 0.75g of carbon nanotube powder, 0.75g of low-melting-point glass powder (total melting temperature: 650℃), 0.03g of sodium carboxymethyl cellulose (manufacturer: Sigma-Aldrich, grade: C9481), 0.03g of silicone defoamer, and 0.03g of silicone leveling agent were added to a 50ml ball mill jar. The mixture was ball-milled at 1000 rpm for 4 hours to obtain a uniformly dispersed graphene heating slurry (A2).

[0139] Preparation of the antioxidant insulating slurry: 30g of an aqueous dispersion of boron nitride nanosheets with a concentration of 50mg / ml was selected, wherein the mass ratio of boron nitride to polyethyleneimine in the dispersion was 1:1. 1g of sodium riboflavin phosphate (manufacturer: Aladdin, grade: R06430), 1.5g of low-melting-point glass powder (total melting temperature: 650℃), 0.05g of sodium carboxymethyl cellulose (manufacturer: Sigma-Aldrich, grade: C9481), 0.03g of silicone defoamer, and 0.03g of silicone leveling agent were added to a 50ml ball mill jar. The mixed slurry was ball-milled at 1000 rpm for 4 hours to obtain a uniformly dispersed antioxidant insulating slurry (B2).

[0140] Riboflavin sodium phosphate has the following structural formula:

[0141]

[0142] Preparation of High-Temperature Resistant Graphene Electrothermal Coating: First, graphene heating slurry was coated onto a ceramic sheet using a scraping method. After 10 minutes, an antioxidant insulating layer slurry was then coated onto the surface of the heating coating using the same scraping method to ensure uniform coverage. After 10 minutes, the coated ceramic sheet was placed in a muffle furnace for curing and sintering. The heating program was set as follows: heating rate 10℃ / min, heating to 150℃, holding for 10 minutes, continuing to heat to 350℃, holding for 10 minutes, continuing to heat to 650℃, holding for 10 minutes, and then stopping heating to allow for natural cooling. After returning to room temperature, tests showed that under 25V voltage, the heating coating rapidly heated to 520℃, an increase of 495℃ compared to before applying any voltage, with uniform temperature on the heating surface and good coating stability.

[0143] The thickness of the graphene electrothermal coating is approximately 38 μm. The thickness of the antioxidant insulating coating is approximately 50 μm.

[0144] Product performance is shown in Table 1.

[0145] See Example 2

[0146] Repeat Example 3, except without using riboflavin sodium phosphate.

[0147] The thickness of the graphene electrothermal coating is approximately 38 μm. The thickness of the antioxidant insulating coating is approximately 50 μm.

[0148] Product performance is shown in Table 1.

[0149] Example 3 (Preferred)

[0150] Preparation of graphene heating slurry: 30g of an aqueous dispersion of graphene with a concentration of 50mg / ml was selected, wherein the mass ratio of graphene to polyacrylamide (manufacturer: Yousuo Chemical, grade: PAM800) in the dispersion was 1:1. 0.75g of carbon nanotube powder, 0.75g of low-melting-point glass powder (total melting temperature 750℃), 0.03g of hydroxyethyl cellulose (manufacturer: Aladdin, grade: H04791), 0.03g of fatty alcohol defoamer (manufacturer: Defeng Defoamer Co., Ltd., grade: DF1303), and 0.03g of silicone leveling agent were added to a 50ml ball mill jar. The mixed slurry was ball-milled at 500 rpm for 4 hours to obtain a uniformly dispersed graphene heating slurry (A3).

[0151] Preparation of the antioxidant insulating slurry: 30g of an aqueous dispersion of boron nitride nanosheets with a concentration of 50mg / ml was selected, wherein the mass ratio of boron nitride to polyacrylamide in the dispersion was 1:1. 0.75g of sodium lignosulfonate (manufacturer: Aladdin, grade: S40863), 1.5g of low-melting-point glass powder (total melting temperature: 750℃), 0.05g of hydroxyethyl cellulose, 0.03g of fatty alcohol defoamer, and 0.03g of silicone leveling agent were added to a 50ml ball mill jar. The mixed slurry was ball-milled at 500 rpm for 4 hours to obtain a uniformly dispersed antioxidant insulating slurry (B3).

[0152] Preparation of High-Temperature Resistant Graphene Electrothermal Coating: First, graphene heating slurry was coated onto a ceramic sheet using a scraping method. After 10 minutes, an antioxidant insulating layer slurry was then coated onto the surface of the heating coating using the same scraping method to ensure uniform coverage. After 10 minutes, the coated ceramic sheet was placed in a muffle furnace for curing and sintering. The heating program was set as follows: heating rate 10℃ / min, heating to 150℃, holding for 10 minutes, continuing to heat to 325℃, holding for 10 minutes, continuing to heat to 750℃, holding for 10 minutes, and then stopping heating to allow for natural cooling. After returning to room temperature, tests showed that under 30V voltage, the heating coating rapidly heated to 600℃, an increase of 575℃ compared to before applying any voltage, with uniform temperature on the heating surface and good coating stability.

[0153] The thickness of the graphene electrothermal coating is approximately 40 μm. The thickness of the antioxidant insulating coating is approximately 60 μm.

[0154] Product performance is shown in Table 1.

[0155] See Example 3

[0156] Repeat Example 3, except without using sodium lignosulfonate.

[0157] The thickness of the graphene electrothermal coating is approximately 40 μm. The thickness of the antioxidant insulating coating is approximately 60 μm.

[0158] Product performance is shown in Table 1.

[0159] Example 4 (Preferred)

[0160] Preparation of graphene heating slurry: 30g of an aqueous dispersion of graphene with a concentration of 50mg / ml was selected, wherein the mass ratio of graphene to sericin (manufacturer: Huaxiang Kejie, purity: 99%) in the dispersion was 1:1. 1.5g of carbon nanotube powder, 0.75g of low-melting-point glass powder (total melting temperature: 850℃), 0.03g of gum arabic (manufacturer: Aladdin, grade: A08976), 0.03g of silicone defoamer, and 0.03g of acrylic leveling agent (manufacturer: Santuo Chemical, grade: STA-3358) were added to a 50ml ball mill jar. The mixture was ball-milled at 500 rpm for 4 hours to obtain a uniformly dispersed graphene heating slurry (A4).

[0161] Preparation of the antioxidant insulating slurry: 30g of an aqueous dispersion of boron nitride nanosheets with a concentration of 50mg / ml was selected, wherein the mass ratio of boron nitride to sericin in the dispersion was 1:1. 0.75g of sodium methylene bis(naphthalene) sulfonate (manufacturer: Keward Chemical, grade: NNO), 1.5g of low-melting-point glass powder (total melting temperature: 850℃), 0.05g of gum arabic, 0.03g of silicone defoamer, and 0.03g of acrylic leveling agent were added to a 50ml ball mill jar. The mixed slurry was ball-milled at 500 rpm for 4 hours to obtain a uniformly dispersed antioxidant insulating slurry (B4).

[0162] Preparation of High-Temperature Resistant Graphene Electrothermal Coating: First, graphene heating slurry was coated onto a ceramic sheet using a scraping method. After 10 minutes, an antioxidant insulating layer slurry was then coated onto the surface of the heating coating using the same scraping method to ensure uniform coverage. After 10 minutes, the coated ceramic sheet was placed in a muffle furnace for curing and sintering. The heating program was set as follows: heating rate 10℃ / min, heating to 150℃, holding for 10 minutes, continuing to heat to 400℃, holding for 10 minutes, continuing to heat to 850℃, holding for 10 minutes, and then stopping heating to allow for natural cooling. After returning to room temperature, tests showed that under 45V voltage, the heating coating rapidly heated to 750℃, an increase of 725℃ compared to before applying any voltage, with uniform temperature on the heating surface and good coating stability.

[0163] The thickness of the graphene electrothermal coating is approximately 40 μm. The thickness of the antioxidant insulating coating is approximately 50 μm.

[0164] Product performance is shown in Table 1.

[0165] See Example 4

[0166] Repeat Example 4, except without using sodium methylene bis(naphthalene) sulfonate.

[0167] The thickness of the graphene electrothermal coating is approximately 40 μm. The thickness of the antioxidant insulating coating is approximately 50 μm.

[0168] Product performance is shown in Table 1.

[0169] See Example 5

[0170] This embodiment does not use an interface bridging agent.

[0171] Preparation of graphene heating slurry: 30g of an aqueous dispersion of graphene with a concentration of 50mg / ml was selected, wherein the mass ratio of graphene to polyvinylpyrrolidone in the dispersion was 1:1. 1.5g of carbon nanotube powder, 0.75g of low-melting-point glass powder (total melting temperature 650℃), 0.1g of gum arabic thickener, 0.03g of silicone defoamer, and 0.03g of acrylic leveling agent were added to a 50ml ball mill jar. The mixture was ball milled at 500 rpm for 4 hours to obtain a uniformly dispersed graphene heating slurry.

[0172] Preparation of the antioxidant insulating layer slurry: 30g of an aqueous dispersion of boron nitride nanosheets with a concentration of 50mg / ml was selected, wherein the mass ratio of boron nitride to polyvinylpyrrolidone in the dispersion was 1:1. 1.5g of low-melting-point glass powder (total melting temperature 650℃), 0.05g of gum arabic, 0.03g of silicone defoamer, and 0.03g of acrylic leveling agent were added to a 50ml ball mill jar. The mixed slurry was ball-milled at 500 rpm for 4 hours to obtain a uniformly dispersed antioxidant insulating layer slurry.

[0173] Preparation of high-temperature resistant graphene electrothermal coating: First, graphene heating slurry was coated onto a ceramic sheet using a scraping method. After standing for 10 minutes, an antioxidant insulating layer slurry was then coated onto the surface of the heating coating using a scraping method to ensure uniform coverage. After standing for 10 minutes, the coated ceramic sheet was placed in a muffle furnace for curing and sintering. The heating program was set as follows: heating rate 10℃ / min, heating to 150℃, holding for 10 minutes, continuing to heat to 400℃, holding for 10 minutes, continuing to heat to 650℃, holding for 10 minutes, then heating was stopped and the material was allowed to cool naturally. After returning to room temperature, testing was conducted.

[0174] The thickness of the graphene electrothermal coating is approximately 40 μm. The thickness of the antioxidant insulating coating is approximately 30 μm.

[0175] Product performance is shown in Table 1.

[0176] See Example 6

[0177] This embodiment does not use one-dimensional conductive filler (carbon nanotubes).

[0178] Preparation of graphene heating slurry: 30g of an aqueous dispersion with a graphene concentration of 50mg / ml was selected, wherein the mass ratio of graphene to polyvinylpyrrolidone in the dispersion was 1:1. 0.75g of low-melting-point glass powder (total melting temperature 650℃), 0.1g of gum arabic (thickener), 0.03g of silicone defoamer, and 0.03g of acrylic leveling agent were added to a 50ml ball mill jar. The mixture was ball-milled at 500 rpm for 4 hours to obtain a uniformly dispersed graphene heating slurry.

[0179] Preparation of the antioxidant insulating layer slurry: 30g of an aqueous dispersion of boron nitride nanosheets with a concentration of 50mg / ml was selected, wherein the mass ratio of boron nitride to polyvinylpyrrolidone in the dispersion was 1:1. 0.75g of sodium riboflavin phosphate, 1.5g of low-melting-point glass powder (total melting temperature 650℃), 0.05g of gum arabic (thickener), 0.03g of silicone defoamer, and 0.03g of acrylic leveling agent were added to a 50ml ball mill jar. The mixed slurry was ball-milled at 500 rpm for 4 hours to obtain a uniformly dispersed antioxidant insulating layer slurry.

[0180] Preparation of high-temperature resistant graphene electrothermal coating: First, graphene heating slurry was coated onto a ceramic sheet using a scraping method. After standing for 10 minutes, an antioxidant insulating layer slurry was then coated onto the surface of the heating coating using a scraping method to ensure uniform coverage. After standing for 10 minutes, the coated ceramic sheet was placed in a muffle furnace for curing and sintering. The heating program was set as follows: heating rate 10℃ / min, heating to 150℃, holding for 10 minutes, continuing to heat to 400℃, holding for 10 minutes, continuing to heat to 650℃, holding for 10 minutes, then heating was stopped and the material was allowed to cool naturally. After returning to room temperature, testing was conducted.

[0181] The thickness of the graphene electrothermal coating is approximately 40 μm. The thickness of the antioxidant insulating coating is approximately 30 μm.

[0182] Product performance is shown in Table 1.

[0183] The experimental results of this embodiment show that the electrothermal conversion efficiency is slightly lower when one-dimensional conductive filler (carbon nanotubes) is not used.

[0184] Comparative Example 1

[0185] This embodiment does not use carbon nanotubes and glass powder (inorganic binder).

[0186] Preparation of graphene heating slurry: 30g of an aqueous dispersion with a graphene concentration of 50mg / ml was selected, wherein the mass ratio of graphene to polyvinylpyrrolidone in the dispersion was 1:1. 0.03g of gum arabic thickener, 0.03g of silicone defoamer, and 0.03g of acrylic leveling agent were added to a 50ml ball mill jar. The mixture was ball-milled at 500 rpm for 4 hours to obtain a uniformly dispersed graphene heating slurry.

[0187] Preparation of the antioxidant insulating layer slurry: 30g of an aqueous dispersion of boron nitride nanosheets with a concentration of 50mg / ml was selected, wherein the mass ratio of boron nitride to polyvinylpyrrolidone in the dispersion was 1:1. 0.75g of sodium riboflavin phosphate, 0.05g of gum arabic, 0.03g of silicone defoamer, and 0.03g of acrylic leveling agent were added to a 50ml ball mill jar. The mixed slurry was ball-milled at 500 rpm for 4 hours to obtain a uniformly dispersed antioxidant insulating layer slurry.

[0188] Preparation of graphene electrothermal coating: First, graphene heating paste was coated onto a ceramic sheet using a scraping method. After standing for 10 minutes, an antioxidant insulating layer paste was then coated onto the surface of the heating coating using a scraping method to ensure uniform coverage. After the surface dried, testing was conducted.

[0189] The thickness of the graphene electrothermal coating is approximately 40 μm. The thickness of the antioxidant insulating coating is approximately 30 μm.

[0190] Product performance is shown in Table 1.

[0191] The experimental results of this embodiment show that when only organic binders are used, the resulting coating cannot withstand high-temperature environments.

[0192] Comparative Example 2

[0193] This embodiment does not use an antioxidant insulating layer.

[0194] Preparation of graphene heating slurry: 30g of an aqueous dispersion with a graphene concentration of 50mg / ml was selected, wherein the mass ratio of graphene to polyvinylpyrrolidone in the dispersion was 1:1. 0.75g of carbon nanotube powder, 0.75g of low-melting-point glass powder (total melting temperature 650℃), 0.03g of gum arabic thickener, 0.03g of silicone defoamer, and 0.03g of acrylic leveling agent were added to a 50ml ball mill jar. The mixture was ball-milled at 500 rpm for 4 hours to obtain a uniformly dispersed graphene heating slurry.

[0195] Preparation of the graphene electrothermal coating: First, the graphene heating slurry was coated onto the ceramic sheet using a scraping method. After 10 minutes, it was allowed to stand for a period of time to achieve uniform coverage. Then, the coated ceramic sheet was placed in a muffle furnace for curing and sintering. The heating program was set as follows: heating rate 10℃ / min, heating to 150℃, holding for 10 minutes, continuing to heat to 400℃, holding for 10 minutes, continuing to heat to 650℃, holding for 10 minutes, then heating was stopped and the sheet was allowed to cool naturally. After returning to room temperature, testing was conducted.

[0196] The thickness of the graphene electrothermal coating is approximately 40 μm.

[0197] Product performance is shown in Table 1.

[0198] The experimental results of this embodiment show that the obtained electrothermal coating cannot withstand high-temperature environments when there is no antioxidant insulating layer.

[0199] Performance testing:

[0200] The graphene electrothermal coatings prepared in the above examples and comparative examples were tested for surface resistivity, adhesion, heat resistance, and electrothermal radiation conversion efficiency. Surface resistivity was measured using a four-probe method to obtain sheet resistance; adhesion was tested according to GB / T9286; and electrothermal radiation conversion efficiency was tested according to GB / T7287. The test results are shown in Table 1. A commercially available organic graphene slurry coating was used as a control group.

[0201] Table 1 - Test Results of Graphene Electrothermal Coating

[0202]

[0203] Note: The test method for heat resistance (long-term operating temperature) is as follows: Under rated voltage and simulated conditions, the component is heated to the specified test temperature at a rate of 1℃ / min, operated for 1 hour, then powered off for 30 minutes to room temperature, with forced cooling allowed. This process is repeated cyclically, and the cumulative operating time is calculated. After the test, the component must function normally, meeting the requirements of tests "Leakage Current at Operating Temperature" (GB4706.1-2005 standard, clause 13.2) and "Electrical Strength at Operating Temperature" (GB4706.23-2007 standard), with a resistance change rate of less than 1% and power attenuation not exceeding 2%.

[0204] As shown in Table 1, the graphene electrothermal coating prepared by this invention has excellent adhesion, reaching level 0, and its sheet resistance is adjustable between 10-200 ohms. Its heat resistance and electrothermal conversion efficiency are far superior to those of commercially available organic graphene slurry coatings and comparative graphene coatings after design adjustments, making it more suitable for widespread use in the field of industrial high-temperature electric heating.

[0205] The content described in the above embodiments is merely an example to illustrate the technical solution of the present invention.

Claims

1. A graphene electrically heated structure (AB), the structure comprising: Substrate; A high-temperature resistant graphene electrothermal coating formed on the surface of a substrate by a high-temperature resistant graphene heating coating (A); An antioxidant insulating coating (B) is formed on the surface of the electrothermal coating; The high-temperature resistant graphene heating coating (A) comprises the following components: (a1) 50-100 parts by weight of high-concentration graphene aqueous dispersion; (a2) 0.3-15 parts by weight of inorganic binder; (a3) ​​0.3-15 parts by weight of conductive additive; (a4) 0.05-2 parts by weight of thickener; (a5) 0-2.2 parts by weight of optional defoamer; (a6) 0-2.2 parts by weight of optional leveling agent; wherein the conductive additive (a3) ​​is selected from one or more of carbon nanotubes, metal powder and polyacetylene powder; wherein the inorganic binder (a2) is a glass powder with a low melting point in the range of 400-1100 °C. The antioxidant insulating coating (B) comprises the following components: (b1) 50-100 parts by weight of a high-concentration boron nitride nanosheet aqueous dispersion; (b2) 0.3-15 parts by weight of an inorganic binder; (b3) 0.1-5 parts by weight of interface bridging agent; (b4) 0.05-2 parts by weight of thickener; (b5) 0-2.2 parts by weight of optional defoamer; (b6) 0-2.2 parts by weight of optional leveling agent; wherein the interface bridging agent (b3) is selected from one or more of sodium lignosulfonate, sodium riboflavin phosphate, and sodium methylene bisnaphthalene sulfonate; wherein the inorganic binder (b2) is glass powder with a low melting point in the range of 400-1100℃.

2. The graphene electrical heating structure (AB) according to claim 1, wherein, Antioxidant insulating coating (B) comprises the following components: (b1) 60-90 parts by weight of high-concentration boron nitride nanosheet aqueous dispersion; (b2) 0.4-13 parts by weight of inorganic binder; (b3) 0.2-4.5 parts by weight of interfacial bridging agent; (b4) Thickener 0.07-1.8 parts by weight; (b5) 0.05-2 parts by weight of defoamer; (b6) Leveling agent 0.05-2 parts by weight.

3. The graphene electrical heating structure (AB) according to claim 2, wherein, Antioxidant insulating coating (B) comprises the following components: (b1) 70-80 parts by weight of high-concentration boron nitride nanosheet aqueous dispersion; (b2) 0.5-10 parts by weight of inorganic binder; (b3) 0.3-4 parts by weight of interfacial bridging agent; (b4) Thickener 0.09-1.6 parts by weight; (b5) 0.07-1.8 parts by weight of defoamer; (b6) Leveling agent 0.07-1.8 parts by weight.

4. The graphene electrical heating structure (AB) according to claim 1, wherein, The sum of the masses of components (b1)-(b6) is 85-100 wt% of the total mass of the antioxidant insulating coating.

5. The graphene electrical heating structure (AB) according to claim 4, wherein, The sum of the masses of components (b1)-(b6) is 87-100 wt% of the total mass of the antioxidant insulating coating.

6. The graphene electrical heating structure (AB) according to claim 5, wherein, The sum of the masses of components (b1)-(b6) is 88-100 wt% of the total mass of the antioxidant insulating coating.

7. The graphene electrical heating structure (AB) according to claim 1, wherein, The high-concentration boron nitride nanosheet aqueous dispersion (b1) comprises the following components: (1) boron nitride nanosheets; (2) polymeric dispersant and (3) water.

8. The graphene electrical heating structure (AB) according to claim 7, wherein, In the high-concentration boron nitride nanosheet aqueous dispersion (b1), the concentration of boron nitride nanosheets (1) is 25~300 mg / mL.

9. The graphene electrical heating structure (AB) according to claim 8, wherein, In the high-concentration boron nitride nanosheet aqueous dispersion (b1), the concentration of boron nitride nanosheets (1) is 30~280 mg / mL.

10. The graphene electrical heating structure (AB) according to claim 9, wherein, In the high-concentration boron nitride nanosheet aqueous dispersion (b1), the concentration of boron nitride nanosheets (1) is 35~270 mg / mL.

11. The graphene electrical heating structure (AB) according to claim 1, wherein, The inorganic binder (b2) has a melting point in the range of 430-1000 °C.

12. The graphene electrical heating structure (AB) according to claim 11, wherein, The inorganic binder (b2) has a melting point in the range of 500-980 °C.

13. The graphene electrical heating structure (AB) according to claim 12, wherein, The inorganic binder (b2) has a melting point in the range of 550-850 °C.

14. The graphene electrical heating structure (AB) according to claim 13, wherein, The inorganic binder (b2) has a melting point in the range of 600-850 °C.

15. The graphene electrical heating structure (AB) according to claim 14, wherein, The inorganic binder (b2) has a melting point in the range of 650-850 °C.

16. The graphene electrical heating structure (AB) according to claim 11, wherein, The particle size or mesh number of low-melting-point glass powder is 800-2500 mesh.

17. The graphene electrical heating structure (AB) according to claim 16, wherein, The particle size or mesh number of low-melting-point glass powder is 1000-2300 mesh.

18. The graphene electrical heating structure (AB) according to claim 17, wherein, The particle size or mesh number of low-melting-point glass powder is 1200-2100 mesh.

19. The graphene electrical heating structure (AB) according to claim 1, wherein, The thickener (b4) is selected from one, two or more of the following: methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxymethylhydroxyethylcellulose, hydroxymethylhydroxypropylcellulose, hydroxyethylhydroxypropylcellulose, hydroxypropylmethylcellulose, sodium carboxymethylcellulose, gum arabic, xanthan gum, sodium alginate, and polyethylene oxide.

20. The graphene electrically heated structure (AB) according to claim 1, wherein... The defoamer (b5) is one or more of the following: silicone defoamer, fatty alcohol defoamer, and polyether defoamer; and / or The leveling agent (b6) is one or more of (poly)acrylic leveling agents and silicone leveling agents.

21. The graphene electrically heated structure (AB) according to claim 1, wherein, The viscosity of the antioxidant insulating coating (B) is 15-700 centipoise.

22. The graphene electrical heating structure (AB) according to claim 21, wherein, The viscosity of the antioxidant insulating coating (B) is 17-500 centipoise.

23. The graphene electrical heating structure (AB) according to claim 22, wherein, The viscosity of the antioxidant insulating coating (B) is 18-400 centipoise.

24. The graphene electrically heated structure (AB) according to claim 7, wherein... In the high-concentration boron nitride nanosheet aqueous dispersion (b1), the mass ratio of boron nitride nanosheets to polymeric dispersant is 0.2-5:1; and / or The polymeric dispersant (2) is selected from one or more of polyvinylpyrrolidone, polyethyleneimine, polyacrylamide, soluble starch, nanocellulose and / or sericin; and / or The sum of the masses of the boron nitride nanosheets (1), the polymeric dispersant (2), and the water (3) is 85-100 wt% of the total mass of the high-concentration boron nitride nanosheet aqueous dispersion.

25. The graphene electrically heated structure (AB) according to claim 24, wherein... In the high-concentration boron nitride nanosheet aqueous dispersion (b1), the mass ratio of boron nitride nanosheets to polymeric dispersant is 0.25-4:1; and / or The sum of the masses of the boron nitride nanosheets (1), the polymeric dispersant (2), and the water (3) is 87-100 wt% of the total mass of the high-concentration boron nitride nanosheet aqueous dispersion.

26. The graphene electrically heated structure (AB) according to claim 25, wherein... In the high-concentration boron nitride nanosheet aqueous dispersion (b1), the mass ratio of boron nitride nanosheets to polymeric dispersant is 0.3-3:1; and / or The sum of the masses of the boron nitride nanosheets (1), the polymeric dispersant (2), and the water (3) is 88-100 wt% of the total mass of the high-concentration boron nitride nanosheet aqueous dispersion.

27. The graphene electrically heated structure (AB) according to claim 7, wherein... The boron nitride nanosheets (1) have a particle size or sheet diameter in the range of 10-500 nm; and / or The relative amounts of (b1) and (b2) should be such that the mass ratio of boron nitride nanosheets to inorganic binder is in the range of 0.4-5:1; and / or The relative amounts of (b1) and (b3) should be such that the mass ratio of boron nitride nanosheets to interfacial bridging agent is in the range of 0.4-5:

1.

28. The graphene electrically heated structure (AB) according to claim 27, wherein... The boron nitride nanosheets (1) have a particle size or sheet diameter in the range of 12-450 nm; and / or The relative amounts of (b1) and (b2) should be such that the mass ratio of boron nitride nanosheets to inorganic binder is in the range of 0.5-4:1; and / or The relative amounts of (b1) and (b3) should be such that the mass ratio of boron nitride nanosheets to interfacial bridging agent is in the range of 0.5-4:

1.

29. The graphene electrically heated structure (AB) according to claim 28, wherein... The particle size or sheet diameter of the boron nitride nanosheets (1) is in the range of 15-420 nm; and / or The relative amounts of (b1) and (b2) should be such that the mass ratio of boron nitride nanosheets to inorganic binder is in the range of 0.6-3:1; and / or The relative amounts of (b1) and (b3) should be such that the mass ratio of boron nitride nanosheets to interfacial bridging agent is in the range of 0.6-3:

1.

30. The graphene electrical heating structure (AB) according to claim 1, wherein, The water-based high-temperature resistant graphene heating coating (A) comprises the following components: (a1) 60-90 parts by weight of high-concentration graphene aqueous dispersion; (a2) 0.4-13 parts by weight of inorganic binder; (a3) Conductive additives 0.4-13 parts by weight; (a4) Thickener 0.07-1.8 parts by weight; (a5) 0.05-2 parts by weight of defoamer; (a6) Leveling agent 0.05-2 parts by weight.

31. A graphene electric heating structure (AB) according to claim 30, wherein, The water-based high-temperature resistant graphene heating coating (A) comprises the following components: (a1) 70-80 parts by weight of high-concentration graphene aqueous dispersion; (a2) 0.5-10 parts by weight of inorganic binder; (a3) 0.5-12 parts by weight of conductive additive; (a4) Thickener 0.09-1.6 parts by weight; (a5) 0.07-1.8 parts by weight of defoamer; (a6) Leveling agent 0.07-1.8 parts by weight.

32. The graphene electrical heating structure (AB) according to claim 1, wherein, The sum of the masses of components (a1)-(a6) is 85-100 wt% of the total mass of the high-temperature resistant graphene heating coating (A).

33. A graphene electric heating structure (AB) according to claim 32, wherein, The sum of the masses of components (a1)-(a6) is 87-100 wt% of the total mass of the high-temperature resistant graphene heating coating (A).

34. The graphene electrical heating structure (AB) according to claim 33, wherein, The sum of the masses of components (a1)-(a6) is 88-100 wt% of the total mass of the high-temperature resistant graphene heating coating (A).

35. The graphene electrical heating structure (AB) according to claim 1, wherein, The high-concentration graphene aqueous dispersion (a1) comprises the following components: (I) graphene; (II) polymeric dispersant and (III) water.

36. A graphene electric heating structure (AB) according to claim 35, wherein, In the aqueous dispersion (a1), the concentration of graphene (I) is 18~250 mg / mL.

37. The graphene electrically heated structure (AB) according to claim 36, wherein, In the aqueous dispersion (a1), the concentration of graphene (I) is 19~220 mg / mL.

38. A graphene electric heating structure (AB) according to claim 37, wherein, In the aqueous dispersion (a1), the concentration of graphene (I) is 20~200 mg / mL.

39. The graphene electrical heating structure (AB) according to claim 1, wherein, The inorganic binder (a2) has a melting point in the range of 430-1000 °C.

40. A graphene electric heating structure (AB) according to claim 39, wherein, The inorganic binder (a2) has a melting point in the range of 500-980 °C.

41. A graphene electric heating structure (AB) according to claim 40, wherein, The inorganic binder (a2) has a melting point in the range of 550-850 °C.

42. A graphene electric heating structure (AB) according to claim 41, wherein, The inorganic binder (b2) has a melting point in the range of 600-850 °C.

43. A graphene electric heating structure (AB) according to claim 42, wherein, The inorganic binder (b2) has a melting point in the range of 650-850 °C.

44. The graphene electrical heating structure (AB) according to claim 39, wherein, The particle size or mesh number of low-melting-point glass powder is 800-2500 mesh.

45. A graphene electric heating structure (AB) according to claim 44, wherein, The particle size or mesh number of low-melting-point glass powder is 1000-2300 mesh.

46. A graphene electric heating structure (AB) according to claim 45, wherein, The particle size or mesh number of low-melting-point glass powder is 1200-2100 mesh.

47. The graphene electrical heating structure (AB) according to claim 1, wherein, Carbon nanotubes include: single-walled carbon nanotubes, double-walled carbon nanotubes, and / or multi-walled carbon nanotubes.

48. The graphene electrically heated structure (AB) according to claim 1, wherein, Metal powders include: copper powder, iron powder, silver powder, zinc powder and / or aluminum powder.

49. The graphene electrical heating structure (AB) according to claim 1, wherein, The thickener (a4) is selected from one, two or more of the following: methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxymethylhydroxyethylcellulose, hydroxymethylhydroxypropylcellulose, hydroxyethylhydroxypropylcellulose, hydroxypropylmethylcellulose, sodium carboxymethylcellulose, gum arabic, xanthan gum, sodium alginate, and polyethylene oxide.

50. The graphene electrically heated structure (AB) according to claim 1, wherein... The defoamer (a5) is one or more of the following: silicone defoamer, fatty alcohol defoamer, and polyether defoamer; and / or The leveling agent (a6) is one or more of (poly)acrylic leveling agents and silicone leveling agents.

51. The graphene electrical heating structure (AB) according to claim 1, wherein, The viscosity of the high-temperature resistant graphene heating coating (A) is 15-700 centipoise.

52. A graphene electric heating structure (AB) according to claim 51, wherein, The viscosity of the high-temperature resistant graphene heating coating (A) is 17-500 centipoise.

53. A graphene electric heating structure (AB) according to claim 52, wherein, The viscosity of the high-temperature resistant graphene heating coating (A) is 18-400 centipoise.

54. A graphene electric heating structure (AB) according to claim 35, wherein, In the high-concentration graphene aqueous dispersion (a1), the mass ratio of graphene to polymeric dispersant is 0.2-5:

1.

55. A graphene electric heating structure (AB) according to claim 54, wherein, In the high-concentration graphene aqueous dispersion (a1), the mass ratio of graphene to polymeric dispersant is 0.25-4:

1.

56. A graphene electric heating structure (AB) according to claim 55, wherein, In the high-concentration graphene aqueous dispersion (a1), the mass ratio of graphene to polymeric dispersant is 0.3-3:

1.

57. A graphene electric heating structure (AB) according to claim 35, wherein, The polymeric dispersant (II) is selected from one or more of polyvinylpyrrolidone, polyethyleneimine, polyacrylamide, soluble starch, nanocellulose, polydiallyldimethylammonium chloride and / or sericin.

58. A graphene electrical heating structure (AB) according to claim 35, wherein, The sum of the masses of the graphene (I), polymeric dispersant (II), and water (III) components is 85-100 wt% of the total mass of the high-concentration graphene aqueous dispersion.

59. A graphene electric heating structure (AB) according to claim 58, wherein, The sum of the masses of the graphene (I), polymeric dispersant (II), and water (III) components is 87-100 wt% of the total mass of the high-concentration graphene aqueous dispersion.

60. A graphene electrical heating structure (AB) according to claim 59, wherein, The sum of the masses of the graphene (I), polymeric dispersant (II), and water (III) components is 88-100 wt% of the total mass of the high-concentration graphene aqueous dispersion.

61. The graphene electrically heated structure (AB) according to claim 35, wherein, The particle size or sheet diameter of graphene (I) is in the range of 0.4-15 µm; and / or The relative amounts of (a1) and (a2) should be such that the mass ratio of graphene to inorganic binder is in the range of 0.4-5:1; and / or The relative amounts of (a1) and (a3) ​​should be such that the mass ratio of graphene to conductive additive is in the range of 0.4-5:

1.

62. The graphene electrically heated structure (AB) according to claim 61, wherein, The particle size or sheet diameter of graphene (I) is in the range of 0.5-13 µm; and / or The relative amounts of (a1) and (a2) should be such that the mass ratio of graphene to inorganic binder is in the range of 0.5-4:1; and / or The relative amounts of (a1) and (a3) ​​should be such that the mass ratio of graphene to conductive additive is in the range of 0.5-4:

1.

63. The graphene electrically heated structure (AB) according to claim 62, wherein, The particle size or sheet diameter of graphene (I) is in the range of 0.7-10 µm; and / or The relative amounts of (a1) and (a2) should be such that the mass ratio of graphene to inorganic binder is in the range of 0.6-3:1; and / or The relative amounts of (a1) and (a3) ​​should be such that the mass ratio of graphene to conductive additive is in the range of 0.6-3:

1.

64. The graphene electric heating structure (AB) according to claim 1, wherein the substrate is microcrystalline glass, ceramic, quartz glass, metal plate or alloy plate with ceramic insulation layer.

65. The graphene electrically heated structure (AB) according to any one of claims 1-63, wherein The high-temperature resistant graphene electrothermal coating is formed by coating and optionally drying the above-mentioned high-temperature resistant graphene electrothermal coating (A); and / or The antioxidant insulating coating is formed by applying and optionally drying the antioxidant insulating coating (B) described above.

66. A graphene electrical heating structure (AB) according to claim 65, wherein, The antioxidant insulating coating is formed by coating, multi-stage heating, melting and cooling of the above-mentioned antioxidant insulating coating (B); multi-stage heating refers to a heating method in which the heating temperature is gradually increased in multiple stages.

67. The graphene electrical heating structure (AB) according to claim 1, wherein, The thickness of the high-temperature resistant graphene electrothermal coating is 15μm~2mm; and / or The thickness of the antioxidant insulating coating is 5-4000μm.

68. A graphene electric heating structure (AB) according to claim 67, wherein, The thickness of the high-temperature resistant graphene electrothermal coating is 20μm~1.5mm; and / or The thickness of the antioxidant insulating coating is 8-3800μm.

69. A graphene electric heating structure (AB) according to claim 68, wherein, The thickness of the high-temperature resistant graphene electrothermal coating is 30μm~1mm; and / or The thickness of the antioxidant insulating coating is 10-3500μm.

70. A method for preparing a graphene electrothermal structure (AB), wherein the graphene electrothermal structure (AB) comprises a substrate, an electrothermal coating (A), and an antioxidant insulating coating (B), the method comprising: 1) The high-temperature resistant graphene heating coating (A) according to any one of claims 1-69 is coated onto a substrate to form a heating layer, optionally followed by drying; and 2) The antioxidant insulating coating (B) of any one of claims 1-69 is applied to the surface of the high-temperature graphene heating coating to form an antioxidant insulating coating, thereby forming a double coating system (AB) on the substrate.

71. The method of claim 70, wherein, The method further includes: 3) Heat the double-coating system (AB) applied to the substrate in step 2) to the first stage temperature of 100~200℃ and heat for 5-10 minutes while maintaining the temperature; 4) Heat the double-coated system (AB) after heat treatment in step 3) to the second stage of 350~550℃ and heat for 5~10 minutes while holding at the temperature; 5) Heat the double-coated system (AB) after heat treatment in step 4) to the third stage of 600~1200℃ and heat for 5~10 minutes under heat preservation for the welding of inorganic binder.

72. The method of claim 71, wherein, The preparation method further includes: 6) Cool the double-coated system (AB) after the heat treatment in step 5) to allow the coating to cure.

73. The method of any one of claims 70-72, wherein, The atmosphere for each step of the preparation method is air or an inert gas.

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