Graphene / h-BN modified heat-conducting cooling anticorrosive coating and preparation method thereof

Abstract

The invention discloses a graphene / h-BN modified heat-conducting cooling anticorrosive coating and a preparation method thereof. The coating is prepared from 100 parts of organic silicon epoxy resin, 15-25 parts of xylene, 10-20 parts of butyl acetate, 30-50 parts of spherical aluminum oxide, 10-20 parts of flaky aluminum oxide, 3-8 parts of hexagonal boron nitride (h-BN), 3-8 parts of zinc oxide, 2-5 parts of boron phosphide, 5-15 parts of flaky aluminum silver paste, 0.1-0.5 part of light graphene oxide and auxiliaries. The preparation process of the coating comprises the following steps: (1) preparing the graphene / h-BN heterojunction composite filler; (2) pre-dispersing the basic filler; (3) low-speed mixing of the functional filler; and (4) adding auxiliaries and preparing a finished product. And (5) coating and curing. The graphene / h-BN heterojunction is constructed to cooperate with the aluminum paste, boron phosphide and other multifunctional fillers, a'reflection-conduction-radiation 'multi-mechanism heat dissipation synergistic system is formed in an organic silicon epoxy resin matrix, and meanwhile, the integrated functions of efficient heat conduction, sunlight reflection, radiation refrigeration and long-acting corrosion prevention are achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of functional protective coating materials, and specifically relates to a composite functional coating suitable for power equipment such as transformers and a preparation method thereof. The coating integrates multiple functions of efficient heat conduction, solar light reflection, radiation cooling and long-acting corrosion prevention, and can effectively solve the hidden dangers and safety risks of power equipment caused by overheating in summer high-temperature environment, and is mainly applied to the surface protection and thermal management of outdoor power equipment such as transformers, circuit breakers and box-type substations. BACKGROUND

[0002] Outdoor power equipment such as transformers faces severe challenges in summer high-temperature climate. On the one hand, the superposition of joule heat generated by equipment operation and environmental high temperature easily leads to rapid internal temperature rise, accelerates the aging of insulation materials, and even causes faults or fire accidents; on the other hand, direct sunlight makes the surface temperature of the equipment further rise, significantly increasing the temperature rise load. At the same time, environmental factors such as humidity and salt fog continue to erode the metal shell, increasing the corrosion risk of the equipment

Energy Reports, 2022, 8, 12568-12580

[0003] To improve the thermal conductivity of the coating, researchers often introduce high thermal conductivity fillers. Carbon materials such as graphene and carbon nanotubes have excellent thermal conductivity, but their electrical conductivity will destroy the electrical insulation performance of the coating, which poses a safety hazard in power equipment applications

ACS Nano, 2021, 15, 20342-20352

[0004] In recent years, multifunctional synergy has become a new idea for coating design. The flaky aluminum silver paste can reduce heat absorption from the source by high reflection of sunlight; boron phosphide and other materials have high emissivity in the 8-13 μm atmospheric window band, which can enhance heat dissipation through radiation cooling effect; and the heterostructure formed by light oxidation of graphene and h-BN through π-π stacking can not only improve the efficiency of the heat conduction network, but also maintain the electrical insulation of the system

Advanced Materials, 2023, 35, 2300185

[0005] The purpose of the present application is to provide a graphene / h-BN modified heat-conducting cooling anticorrosion coating and a preparation method thereof. In view of the defects in the prior art, a "reflection-conduction-radiation" multi-mechanism heat dissipation synergistic system is formed in the organic silicon epoxy resin matrix by constructing a graphene / h-BN heterojunction with aluminum silver paste and boron phosphide and other multifunctional fillers, which simultaneously realizes the integration of efficient heat conduction, sunlight reflection, radiation refrigeration and long-term corrosion protection.

[0006] In order to solve the above technical problems, the following technical solutions are adopted.

[0007] The graphene / h-BN modified heat-conducting cooling anticorrosion coating comprises organic silicon epoxy resin 100 parts, dimethylbenzene 15-25 parts, butyl acetate 10-20 parts, spherical aluminum oxide 30-50 parts, flaky aluminum oxide 10-20 parts, hexagonal boron nitride (h-BN) 3-8 parts, zinc oxide 3-8 parts, boron phosphide 2-5 parts, flaky aluminum silver paste 5-15 parts, light graphene oxide 0.1-0.5 parts and additives.

[0008] After optimization, the additives include defoaming agent 0.1-0.5 parts, leveling agent 0.2-1 part, and amino silane curing agent 10-20 parts.

[0009] After optimization, the defoaming agent is selected from one or more of polyacrylate copolymer defoaming agent, non-silicon polymer defoaming agent, fluorocarbon modified polydimethylsiloxane defoaming agent, bubble-breaking polymer defoaming agent, and mineral oil composite defoaming agent; the leveling agent is selected from one or more of polyacrylate leveling agent, fluorocarbon copolymer leveling agent, polyether modified siloxane leveling agent, silicone modified leveling agent, and acrylate copolymer leveling agent.

[0010] The preparation method of the graphene / h-BN modified heat-conducting cooling anticorrosion coating comprises the following steps.

[0011] (1) Preparation of graphene / h-BN heterojunction composite filler.

[0012] The slightly oxidized graphene is dispersed in anhydrous ethanol at a solid-liquid ratio of 1:50-1:100 (g / mL), and a silane coupling agent KH-560 is added, the amount of the silane coupling agent being 20%-30% of the mass of the graphene, and mechanical stirring is carried out under the condition of a water bath at 60-70°C; then hexagonal boron nitride is added, the mass ratio of the hexagonal boron nitride to the graphene being 10:1-20:1, and ultrasonic treatment is carried out; the reaction product is subjected to suction filtration, washed with ethanol for 2-3 times, and dried in a vacuum drying oven at 60-80°C for 6-12 hours to obtain the graphene / h-BN heterojunction composite filler.

[0013] (2) Pre-dispersion of the base filler.

[0014] The silicone epoxy resin, dimethylbenzene and butyl acetate are added to a container, stirred and mixed, and spherical alumina, flaky alumina and zinc oxide are sequentially added to obtain a uniform base filler slurry.

[0015] (3) Low-speed mixing of the functional filler.

[0016] The slurry obtained in step (2) is stirred at a reduced speed, and the following fillers are sequentially added: graphene / h-BN heterojunction composite filler, boron phosphide and flaky aluminum paste, to obtain a mixed slurry.

[0017] (4) Addition of an auxiliary agent and preparation of a finished product.

[0018] An auxiliary agent is added to the mixed slurry obtained in step (3) to obtain a final coating product.

[0019] (5) Coating and curing.

[0020] The coating of step (4) is applied to the surface of a pretreated metal substrate in a manner of blade coating or spraying, and a dense composite coating is formed after curing.

[0021] Preferably, in step (1), the hexagonal boron nitride has a flaky structure, a particle size of 1-5 μm, a thickness of 0.1-1 μm, and a specific surface area of 10-30 m² / g; the slightly oxidized graphene has a carbon-oxygen ratio of 4:1-8:1, a number of layers of 1-5, and a flake size of 1-10 μm.

[0022] Preferably, in step (1), the mechanical stirring speed is 200-400 rpm, and the stirring time is 1-2 hours; the ultrasonic treatment power is 300-500 W, and the ultrasonic treatment time is 0.5-1.5 hours; the ultrasonic treatment power is further preferably 400 W, and the ultrasonic treatment time is further preferably 1 hour, under which conditions a stable π-π stacking structure can be formed without damaging the two-dimensional morphology of the filler.

[0023] Preferably, in the step (2), the stirring speed is 1200-1500 rpm, and the stirring time is 30-45 minutes. Further preferably, the stirring speed is 1200-1500 rpm, and the stirring time is 40 minutes, so as to ensure the dispersion of the base filler and not to affect the subsequent process.

[0024] Preferably, in the step (3), the stirring speed is reduced to 300-500 rpm, so as to ensure the structural integrity of the sensitive filler. Further preferably, the stirring speed is reduced to 400 rpm.

[0025] Preferably, in the step (3), the stirring time is 15-20 minutes after the addition of the graphene / h-BN heterojunction composite filler, 15-20 minutes after the addition of boron phosphide, and 20-30 minutes after the addition of the flaky aluminum silver paste. Further preferably, the interval time between the addition of each filler is 20 minutes.

[0026] The functional filler addition sequence is specially designed: the graphene / h-BN heterojunction composite filler is added first, which provides a dispersion basis for the subsequent fillers due to its good interface compatibility; then boron phosphide is added, which fills the voids due to its nanoscale effect; finally, the flaky aluminum silver paste is added, which is arranged in the surface layer of the coating to form a reflection layer.

[0027] Preferably, in the step (4), the addition of the additives includes: adding a defoaming agent and a leveling agent in the mixed slurry obtained in the step (3), continuing to stir at a speed of 300-500 rpm for 5-10 minutes, then adding a curing agent, and continuing to stir for 10-15 minutes. Finally, the product is filtered through a 100-200 mesh screen. Further preferably, the filter screen is 150 mesh, and the stirring speed is 400 rpm, so as to ensure the construction performance of the coating and not to affect the dispersion state of the fillers.

[0028] Preferably, in the step (5), the wet film thickness is controlled to be 150-250 μm, and the film is cured in a 80-150℃ oven for 1-2 hours, so as to form a dense composite coating with a dry film thickness of 60-100 μm. Further preferably, the curing program adopts a stepwise temperature rising mode of 80℃ / 30 minutes+150℃ / 60 minutes, the wet film thickness is 200 μm, and the dry film thickness is 80 μm, so as to ensure the optimization of the coating performance.

[0029] Due to the above technical solutions, the following beneficial effects are achieved.

[0030] (1) The graphene / h-BN modified thermally conductive and cooling anti-corrosion coating proposed in this invention has the following unique advantages: the coating constructs a triple heat dissipation mechanism of "reflection-conduction-radiation" through the synergistic effect of graphene / h-BN heterojunction and multi-scale fillers; the structural integrity of each functional filler is ensured through a strict low-speed mixing process; and the electrical insulation of the coating is maintained while ensuring excellent thermal conductivity through optimized formulation design.

[0031] (2) By constructing graphene / h-BN heterojunction, the problem of dispersion of two-dimensional filler is solved, and an efficient phonon transport channel is created, so that the coating can achieve a thermal conductivity of 3.0~4.0 W·m⁻¹·K⁻¹ while maintaining electrical insulation.

[0032] (3) By using the surface orientation of aluminum silver paste and the high infrared emission characteristics of boron phosphide, a synergistic cooling effect of solar reflectivity ≥85% and mid-infrared emissivity ≥0.94 is achieved, which can reduce the surface temperature of the equipment by 10~20℃.

[0033] (4) Through the gradation design of multi-scale fillers and the barrier effect of organosilicon epoxy resin, the coating has excellent anti-corrosion performance and salt spray resistance time of more than 1000 hours.

[0034] (5) Through a step-by-step sequential mixing process, efficient dispersion of multiple functional fillers is achieved without grinding damage. The process is simple and reliable and suitable for large-scale production.

[0035] (6) The overall heat dissipation performance of the coating is improved by more than 60% compared with the traditional single-mechanism coating, and it has a longer service life.

[0036] (7) All raw material costs are controllable, the process is environmentally friendly, and it has good economic benefits and market promotion value. Attached Figure Description

[0037] The invention will now be further described with reference to the accompanying drawings.

[0038] Figure 1 Schematic diagram of the adsorption modification principle of graphene and h-BN.

[0039] Figure 2 This is a schematic diagram of the thermally conductive coating. Detailed Implementation

[0040] This invention aims to provide a thermally conductive, cooling, and anti-corrosion coating based on graphene / h-BN heterojunction and multi-mechanism synergistic heat dissipation, and its preparation method. The resulting coating has excellent solar reflectivity, high thermal conductivity, significant radiative cooling effect, and long-lasting anti-corrosion protection, providing an innovative technical solution for solving the overheating and corrosion problems of outdoor power equipment such as transformers in high-temperature environments in summer.

[0041] The present invention will now be described in detail with reference to specific embodiments. Example 1.

[0042] 0.3 g of lightly oxidized graphene was weighed and dispersed in 30 mL of anhydrous ethanol. 0.075 g of silane coupling agent KH-560 was added, and the mixture was mechanically stirred at 300 rpm for 1.5 hours in a water bath at 65°C. Subsequently, 4.5 g of hexagonal boron nitride was added, and the mixture was ultrasonically treated at 400 W for 1 hour. The reaction product was filtered, washed three times with ethanol, and vacuum dried at 70°C for 8 hours to obtain the graphene / h-BN heterojunction composite filler.

[0043] Add 100 g of organosilicon epoxy resin, 20 g of xylene, and 15 g of butyl acetate to a 500 mL container. Adjust the stirring speed to 1500 rpm, and then add 25 g of spherical alumina (1 μm particle size), 10 g of spherical alumina (20 μm particle size), 15 g of flake alumina, and 5 g of zinc oxide in sequence. Continue stirring at high speed for 40 minutes to obtain a uniform basic filler slurry.

[0044] Reduce the rotation speed to 400 rpm and add the following fillers in sequence.

[0045] (1) 4.8 g of the graphene / h-BN heterojunction composite filler prepared above was stirred at low speed for 20 minutes.

[0046] (2) Add 3 g of boron phosphide and stir at low speed for 20 minutes.

[0047] (3) 8 g of sheet aluminum silver paste, stir at low speed for 25 minutes.

[0048] Add 0.3 g of silicone defoamer and 0.5 g of polyether-modified polysiloxane leveling agent, and stir at 400 rpm for 8 minutes. Finally, add 15 g of aminosilane curing agent, continue stirring at low speed for 12 minutes, and filter through a 150-mesh sieve to obtain the composite coating.

[0049] The coating was applied to a sandblasted Q235 steel plate (100 mm × 50 mm × 2 mm) with a wet film thickness of 200 μm. It was pre-cured in an oven at 80℃ for 30 minutes, then cured in an oven at 150℃ for 60 minutes to obtain a coating with a dry film thickness of 80 ± 5 μm.

[0050] Performance testing: The thermal conductivity of the coating was measured to be 3.52 W / (m·K) using a laser thermal conductivity meter; no blistering or peeling was observed after 2000 hours of salt spray testing according to GB / T1771-2007; the adhesion was rated as grade 0 according to GB / T9286-1998; the surface temperature of the coating was 12.5℃ lower than that of the uncoated substrate under standard sunlight irradiation, as measured by an infrared thermal imager; the volume resistivity was 5.6×10¹² Ω·cm. Example 2.

[0051] Preparation of graphene / h-BN heterojunction composite filler: Weigh 0.2 g of lightly oxidized graphene, disperse it in 25 mL of anhydrous ethanol, add 0.05 g of KH-560, and stir in a 60℃ water bath for 2 hours. Add 4.0 g of hexagonal boron nitride, and sonicate at 350 W for 1.5 hours. Post-treatment is the same as in Example 1.

[0052] Base material preparation: Add 100 g of organosilicon epoxy resin, 18 g of xylene, and 12 g of butyl acetate to a container. Then, add 30 g of spherical alumina, 12 g of flake alumina, and 6 g of zinc oxide in sequence at 1500 rpm and stir at high speed for 45 minutes.

[0053] Low-speed mixing stage (400 rpm): 4.2 g of graphene / h-BN heterojunction composite filler, 4 g of boron phosphide, and 12 g of flake aluminum silver paste were added sequentially, with each filler stirred for 20 minutes at intervals.

[0054] Add 0.4 g of defoamer and 0.6 g of leveling agent, stir at 400 rpm for 10 minutes, then add 18 g of curing agent and continue stirring for 15 minutes. Filter to obtain the coating, using the same process as in Example 1.

[0055] The coating and curing conditions are the same as in Example 1.

[0056] Performance testing: Coating thermal conductivity 3.78 W / (m·K), no corrosion after 2200 hours of salt spray test, adhesion grade 0, surface temperature drop 16.3℃, volume resistivity 4.9×10¹² Ω·cm. Example 3.

[0057] Preparation of graphene / h-BN heterojunction composite filler: Weigh 0.4 g of lightly oxidized graphene, 0.12 g of KH-560, and 6.0 g of hexagonal boron nitride. The preparation process is the same as in Example 1.

[0058] Base material preparation: 100 g of organosilicon epoxy resin, 22 g of xylene, and 18 g of butyl acetate were added sequentially at 1500 rpm, along with 40 g of spherical alumina, 18 g of flake alumina, and 4 g of zinc oxide. The mixture was stirred at high speed for 35 minutes.

[0059] Low-speed mixing: 6.4 g of graphene / h-BN heterojunction composite filler, 2 g of boron phosphide, and 10 g of flake aluminum silver paste were added sequentially, with the process being the same as in Example 1.

[0060] Add 0.3 g of defoamer, 0.5 g of leveling agent, and 16 g of curing agent, and follow the same process as in Example 1.

[0061] The coating and curing conditions are the same as in Example 1.

[0062] Performance testing: Coating thermal conductivity 3.25 W / (m·K), no blistering after 1800 hours of salt spray test, adhesion grade 1, surface temperature drop 11.8℃, volume resistivity 6.2×10¹² Ω·cm.

[0063] Comparative Example 1.

[0064] Without using graphene / h-BN heterojunction composite filler, 6.0 g of hexagonal boron nitride was directly physically mixed with other fillers, and the preparation process was the same as in Example 1.

[0065] Performance testing: The coating has a thermal conductivity of 1.86 W / (m·K), obvious blistering occurred after 800 hours of salt spray testing, the adhesion is grade 2, and the surface temperature drop is 2.2℃.

[0066] Comparative Example 2.

[0067] Using a traditional grinding process, all fillers were mixed and ground in a sand mill for 30 minutes, with other conditions the same as in Example 1.

[0068] Performance testing: The coating has a thermal conductivity of 2.45 W / (m·K). After 1200 hours of salt spray testing, localized corrosion occurred, the sheet-like aluminum silver paste structure was severely damaged, and the surface temperature dropped by 5.5℃. The results are shown in Table 1.

[0069] Table 1. Comparison of test results between Examples 1-3 and Comparative Examples 1-2.

[0070] Item Thermal conductivity (W / m-K) Salt spray test (h) Adhesion (grade) Surface temperature drop (°C) Volume resistivity (Ω-cm) Example 1 3.52 2000 0 12.5 5.6×10¹² Example 2 3.78 2200 0 16.3 4.9×10¹² Example 3 3.25 1800 1 11.8 6.2×10¹² Comparative Example 1 1.86 800 2 2.2 3.8×10¹² Comparative Example 2 2.45 1200 2 5.5 4.1×10¹² As shown in Table 1, the coatings of the embodiments of the present invention are significantly superior to the comparative examples in terms of thermal conductivity, corrosion resistance, and cooling effect. Specifically, this is evident in…

[0071] The thermal conductivity of Examples 1-3 (3.25-3.78 W / m·K) is approximately 75%-103% higher than that of Comparative Example 1 (1.86 W / m·K), demonstrating that the graphene / h-BN heterojunction effectively improves the efficiency of the heat-conducting network. All examples exhibit salt spray resistance exceeding 1800 hours, an improvement of over 125% compared to the comparative example, reflecting the enhanced corrosion resistance effect of optimized multi-scale filler distribution. The surface temperature reduction of the coatings in the examples reaches 11.8-16.3℃, significantly higher than the 2.2-5.5℃ reduction in the comparative example, verifying the effectiveness of the "reflection-conduction-radiation" triple synergistic heat dissipation mechanism. Simultaneously, all examples maintain excellent electrical insulation properties, with volume resistivity exceeding 4.9 × 10¹² Ω·cm.

[0072] Experiments revealed that in Comparative Example 2, prepared using traditional grinding processes, the aspect ratio of the flake aluminum silver paste decreased by approximately 60%, and the boron phosphide particles showed significant breakage, resulting in a 35% reduction in the coating's solar reflectivity and a 25% reduction in its infrared emissivity. In contrast, the coating prepared using the method of this invention maintained the complete morphological characteristics of each functional filler, forming a more efficient functional network.

[0073] The above embodiments fully demonstrate the effectiveness and superiority of the graphene / h-BN heterostructure construction method and stepwise sequential mixing process provided by the present invention. While maintaining good processability, each embodiment achieves a synergistic improvement in thermal conductivity, cooling, and corrosion resistance, thus achieving the intended purpose of the present invention.

[0074] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A graphene / h-BN modified thermally conductive, cooling, and corrosion-resistant coating, characterized in that: The coating comprises 100 parts of silicone epoxy resin, 15-25 parts of xylene, 10-20 parts of butyl acetate, 30-50 parts of spherical alumina, 10-20 parts of flake alumina, 3-8 parts of hexagonal boron nitride (h-BN), 3-8 parts of zinc oxide, 2-5 parts of boron phosphide, 5-15 parts of flake aluminum silver paste, 0.1-0.5 parts of lightly oxidized graphene, and additives.

2. The graphene / h-BN modified thermally conductive, cooling, and corrosion-resistant coating according to claim 1, characterized in that: The additives include 0.1 to 0.5 parts of defoamer, 0.2 to 1 part of leveling agent, and 10 to 20 parts of aminosilane curing agent.

3. The graphene / h-BN modified thermally conductive, cooling, and corrosion-resistant coating according to claim 2, characterized in that: The defoamer is selected from one or more of the following: polyacrylate copolymer defoamer, non-silicone polymer defoamer, fluorocarbon modified polydimethylsiloxane defoamer, defoaming polymer defoamer, and mineral oil composite defoamer; the leveling agent is selected from one or more of the following: polyacrylate leveling agent, fluorocarbon copolymer leveling agent, polyether modified siloxane leveling agent, organosilicon modified leveling agent, and acrylate copolymer leveling agent.

4. The preparation method of the graphene / h-BN modified thermally conductive, cooling, and corrosion-resistant coating as described in claim 1, characterized in that... Includes the following steps: (1) Preparation of graphene / h-BN heterojunction composite filler Lightly oxidized graphene was dispersed in anhydrous ethanol at a solid-liquid ratio of 1:50 to 1:100 (g / mL), and silane coupling agent KH-560 was added. The amount of silane coupling agent was 20% to 30% of the mass of graphene. The mixture was mechanically stirred in a water bath at 60 to 70°C. Subsequently, hexagonal boron nitride was added at a mass ratio of 10:1 to 20:1 to graphene, and the mixture was ultrasonically treated. The reaction product was filtered, washed 2 to 3 times with ethanol, and dried in a vacuum drying oven at 60 to 80°C for 6 to 12 hours to obtain graphene / h-BN heterojunction composite filler. (2) Pre-dispersion of basic filler Add organosilicon epoxy resin, xylene and butyl acetate to a container, stir and mix, and then add spherical alumina, flake alumina and zinc oxide in sequence to obtain a uniform base filler slurry; (3) Low-speed mixing of functional fillers Reduce the stirring speed of the slurry obtained in step (2), and add the following fillers in sequence: graphene / h-BN heterojunction composite filler, boron phosphide and flake aluminum silver paste to obtain a mixed slurry; (4) Additives and finished product preparation Additives are added to the mixed slurry obtained in step (3) to obtain the final coating product; (5) Coating and curing The coating from step (4) is applied to the surface of the pretreated metal substrate by scraping or spraying, and after curing, a dense composite coating is formed.

5. The method for preparing the graphene / h-BN modified thermally conductive, cooling, and corrosion-resistant coating according to claim 4, characterized in that: In step (1), the hexagonal boron nitride has a sheet-like structure with a particle size of 1~5 μm, a thickness of 0.1~1 μm, and a specific surface area of ​​10~30 m² / g; the lightly oxidized graphene has a carbon-oxygen ratio of 4:1~8:1, 1~5 layers, and a sheet diameter of 1~10 μm.

6. The method for preparing the graphene / h-BN modified thermally conductive, cooling, and corrosion-resistant coating according to claim 4, characterized in that: In step (1), the mechanical stirring speed is 200~400 rpm and the stirring time is 1-2 hours; the ultrasonic treatment power is 300~500 W and the ultrasonic treatment time is 0.5~1.5 hours.

7. The method for preparing the graphene / h-BN modified thermally conductive, cooling, and corrosion-resistant coating according to claim 4, characterized in that: In step (2), the stirring speed is 1200~1500 rpm and the stirring time is 30-45 minutes.

8. The method for preparing the graphene / h-BN modified thermally conductive, cooling, and corrosion-resistant coating according to claim 4, characterized in that: In step (3), the stirring speed is reduced to 300-500 rpm; after adding graphene / h-BN heterojunction composite filler, the mixture is stirred for 15-20 minutes; after adding boron phosphide, the mixture is stirred for 15-20 minutes; and after adding flake aluminum silver paste, the mixture is stirred for 20-30 minutes.

9. The method for preparing the graphene / h-BN modified thermally conductive, cooling, and corrosion-resistant coating according to claim 4, characterized in that: The process of adding additives in step (4) includes: adding defoamer and leveling agent to the mixed slurry obtained in step (3), stirring at 300-500 rpm for 5-10 minutes, then adding curing agent, stirring for 10-15 minutes, and filtering through a 100-200 mesh sieve to obtain the final coating product.

10. The method for preparing the graphene / h-BN modified thermally conductive, cooling, and corrosion-resistant coating according to claim 4, characterized in that: In step (5), the wet film thickness is controlled at 150~250 μm, and the film is cured in an oven at 80~150℃ for 1~2 hours to form a dense composite coating with a dry film thickness of 60~100 μm.

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