Heat-conducting and wave-absorbing coating based on organic silicon precursor and preparation method of heat-conducting and wave-absorbing coating

Abstract

The invention relates to a heat-conducting and wave-absorbing coating based on an organic silicon precursor and a preparation method of the heat-conducting and wave-absorbing coating. The composition comprises the following components in parts by weight: 5-15 parts of vinyl silicone oil; 2-5 parts of hydrogen-containing silicone oil; 0.16 to 0.5 part of a coupling agent; 0.01 to 0.02 part of a catalyst; 10 to 40 parts of insulated coated carbonyl iron subjected to surface treatment; 5 to 15 parts of boron nitride subjected to surface treatment; 10 to 30 parts of aluminum oxide subjected to surface treatment; and 10-20 parts of silicon carbide. Through filler surface treatment and a structured dispersion process, the contradiction between wave absorption and insulation performance is solved, and through an innovative stepped heating curing procedure, the heat-conducting and wave-absorbing integrated organic silicon coating capable of being cured at medium and low temperatures (less than or equal to 200 DEG C) is prepared. According to the invention, the material can be converted into SiOC and other ceramic matrixes through a high-temperature ceramic treatment process.

Description

Technical Field

[0001] This invention relates to multifunctional coating materials, and in particular to thermally conductive and microwave-absorbing coatings based on organosilicon precursors and their preparation methods. Background Technology

[0002] With the rapid development of technologies such as 5G / 6G mobile communication, artificial intelligence (AI) computing, and high-performance radar, their core chips and modules are evolving towards higher power density, higher frequency, and higher speed. This has led to a severe challenge in the coordinated management of thermal and electromagnetic signals, which has become a key bottleneck restricting system performance, reliability, and miniaturization. On the one hand, the surge in chip power consumption necessitates the timely removal of a large amount of waste heat; otherwise, performance degradation or even failure will occur. On the other hand, electromagnetic leakage and interference (EMI) generated by high-frequency signals can severely affect the signal integrity of the chip itself and surrounding circuits.

[0003] In existing technologies, thermally conductive and microwave-absorbing coatings are generally used to solve the above problems. However, existing thermally conductive and microwave-absorbing materials have the following problems: their microwave absorption performance decreases in high-temperature environments, and it is not easy to balance microwave absorption and insulation performance. For example, single-functional coatings based on traditional polymers such as epoxy resin and polyurethane, although simple to process, have a "performance ceiling": their temperature resistance, long-term stability, and mechanical strength are limited, and they will decompose and carbonize when exposed to unexpected high temperatures, losing their function or even causing secondary risks. They cannot meet the stringent requirements of extreme environments for materials to be "lightweight, resistant to extreme environments, and long-lasting". Summary of the Invention

[0004] Based on this, a thermally conductive and microwave-absorbing coating based on an organosilicon precursor is provided. The resulting coating maintains good thermal conductivity and microwave absorption performance even in high-temperature environments, and can balance microwave absorption and insulation properties.

[0005] A thermally conductive and microwave-absorbing coating based on an organosilicon precursor, comprising, by weight: Vinyl silicone oil, 5-15 parts; Hydrogen-containing silicone oil, 2-5 parts; Coupling agent, 0.16-0.5 parts; Catalyst, 0.01-0.02 parts; Surface-treated insulating carbonyl iron, 10-40 parts; Surface-treated boron nitride, 5-15 parts; Surface-treated alumina, 10-30 parts; Silicon carbide, 10-20 parts.

[0006] In one embodiment, the surface-treated insulating carbonyl iron comprises: a mixture of silane coupling agent and ethanol sprayed onto insulating carbonyl iron powder, dispersed at high speed under vacuum, and then dried.

[0007] In one embodiment, the surface-treated boron nitride comprises: spraying a mixture of silane coupling agent and ethanol onto sheet-like boron nitride, dispersing it under vacuum, and then drying it.

[0008] In one embodiment, the surface-treated alumina comprises: a mixture of silane coupling agent and ethanol sprayed onto spherical alumina, dispersed under vacuum, and then dried.

[0009] In one embodiment, the average diameter of the sheet-like boron nitride is 30 μm, and the spherical alumina has two average particle sizes of 40 μm and 1 μm, respectively.

[0010] In one embodiment, a vinyl silicone oil with a viscosity of 200-500 cps and a hydrogen-containing silicone oil with a viscosity of 10-90 cps constitute an addition-curing system.

[0011] In one embodiment, the silicon carbide comprises: silicon carbide with an average particle size of 40 μm, and surface-treated insulating coated carbonyl iron with an average particle size of 5 μm.

[0012] In one embodiment, the coupling agent includes at least one of the following: silane coupling agent KH550, silane coupling agent KH560, silane coupling agent A-151, silane coupling agent trimethoxy-n-octylsilane, silane coupling agent trimethoxy-n-decane, silane coupling agent KH560, silane coupling agent hexadecyltriethoxysilane, and silane coupling agent hexadecyltrimethoxysiloxane.

[0013] A method for preparing a thermally conductive and microwave-absorbing coating based on an organosilicon precursor includes, firstly, mixing the various components in a specific ratio. Then a curing process is performed, which includes: holding at 80°C for 1 hour, then at 120°C for 1 hour, then at 150°C for 1 hour, then at 180°C for 2 hours, then at 200°C for 4-6 hours, followed by natural cooling.

[0014] A method for preparing a thermally conductive and microwave-absorbing ceramic coating based on an organosilicon precursor includes, firstly, mixing the various components in a specific ratio. Then a curing process is performed, which includes: holding at 80°C for 1 hour, then at 120°C for 1 hour, then at 150°C for 1 hour, then at 180°C for 2 hours, then at 200°C for 4-6 hours, followed by natural cooling, and then, under the protection of inert gas in a tube furnace, the temperature is increased to 900°C at a rate of 5°C / min, then held for 1 hour, and then cooled with the furnace.

[0015] The beneficial effects of this application are: This application resolves the performance contradiction between microwave absorption and insulation through filler surface treatment and structured dispersion processes. Then, through an innovative stepped temperature curing procedure, it prepares a thermally conductive and microwave-absorbing integrated silicone coating that can be cured at medium to low temperatures (≤200°C). Alternatively, a high-temperature ceramicization process can be used to transform the material into a ceramic matrix such as SiOC, resulting in a revolutionary performance improvement. This two-stage process of "low-temperature curing (200°C) to form a protective layer + optional high-temperature ceramicization" is significantly different from existing technologies and is a unique process of this application. The first stage can obtain a conventional high-performance coating, while the second stage can generate a high-temperature resistant ceramicized reinforcement layer on the coating surface in situ without damaging the overall device, achieving a "performance leap" from polymer to ceramic in a single coating. This application provides a continuous and controllable performance upgrade path from "high-performance polymer coatings" to "ceramic-like composite coatings," offering a continuous, controllable, and reliable solution for integrated heat dissipation and electromagnetic compatibility protection of high-power, high-frequency electronic devices. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the reflection loss in Example 1.

[0017] Figure 2 This is a schematic diagram of the reflection loss in Example 2.

[0018] Figure 3 This is a schematic diagram of the reflection loss in Example 3.

[0019] Figure 4 This is a schematic diagram of the reflection loss in Comparative Example 4.

[0020] Figure 5 This is a schematic diagram of the reflection loss in Comparative Example 5.

[0021] Figure 6 A schematic diagram of an aluminum plate and the aluminum plate coated with the material of this application. Detailed Implementation

[0022] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0023] First, this application features an innovative design at the material system level. It selects insulating-coated carbonyl iron, such as silica-coated carbonyl iron powder. While imparting magnetic loss absorption capability to the coating, its insulating shell ensures the overall high resistivity of the coating, resolving the core contradiction of electrical insulation failure caused by traditional magnetic fillers. The synergistic and reinforcing thermally conductive filler in this application is reflected in the use of a composite system of lamellar boron nitride and spherical alumina of various particle sizes. While constructing a highly efficient three-dimensional thermally conductive network, its inherent high-temperature stability provides skeletal support for the dimensional and performance stability of the matrix at high temperatures.

[0024] This application discloses a thermally conductive and microwave-absorbing coating based on an organosilicon precursor, comprising, by weight: Vinyl silicone oil, 5-15 parts; Hydrogen-containing silicone oil, 2-5 parts; Coupling agent, 0.16-0.5 parts; Catalyst, 0.01-0.02 parts; Surface-treated insulating carbonyl iron, 10-40 parts; Surface-treated boron nitride, 5-15 parts; Surface-treated alumina, 10-30 parts; Silicon carbide, 10-20 parts.

[0025] It is understood that the coupling agent may be: silane coupling agent KH550, silane coupling agent KH560, silane coupling agent A-151, silane coupling agent trimethoxy-n-octylsilane, silane coupling agent trimethoxy-n-decane, silane coupling agent KH560, silane coupling agent hexadecyltriethoxysilane, and silane coupling agent hexadecyltrimethoxysiloxane, etc.

[0026] For example, the coupling agent can be 0.04-0.2 parts of silane coupling agent KH560, 0.02-0.1 parts of silane coupling agent A-151, or 0.1-0.2 parts of silane coupling agent undecyltrimethoxysiloxane.

[0027] The catalyst can be a platinum catalyst. Boron nitride can be plate-shaped boron nitride, alumina can be nearly spherical alumina, and silicon carbide can be nearly spherical silicon carbide.

[0028] The ratio of hydrogen-containing silicone oil to vinyl silicone oil is such that the molar ratio of Si-H to Si-Vi is 1.2:1-1.5:1, which ensures sufficient cross-linking. The total content of thermally conductive and microwave-absorbing fillers does not exceed 90%, ensuring that the coating can be applied to the device surface. By setting the raw materials within the above ratio range, an integrated thermally conductive and microwave-absorbing coating can be prepared.

[0029] Specifically, a vinyl silicone oil with a viscosity of 200-500 cps and a hydrogen-containing silicone oil with a viscosity of 10-90 cps are preferred to form an addition-curing system. This viscosity combination ensures the fluidity of the resin while helping to fully impregnate and uniformly disperse a high proportion of functional fillers, which is the basis for obtaining high-performance composite coatings.

[0030] Specifically, the thermal conductivity is achieved through the synergistic effect of lamellar boron nitride and spherical alumina of various particle sizes. Lamellar boron nitride (average particle size 30 μm), with its extremely high intrinsic thermal conductivity, excellent insulation, and outstanding high-temperature stability, primarily constructs efficient in-plane thermal conductivity pathways and ensures the overall electrical insulation and thermal stability of the coating. Spherical alumina, as the basic thermally conductive filler, allows for close packing of particles of different sizes (average particle sizes of 40 μm and 1 μm), effectively filling the resin matrix and constructing a three-dimensional thermally conductive framework. This complements the lamellar boron nitride spatially, jointly enhancing the coating's thermal conductivity and structural stability.

[0031] Specifically, the microwave absorption function is achieved through a combined mechanism of dielectric loss and magnetic loss. Silicon carbide (average particle size 40 μm), as a dielectric loss filler, possesses both excellent thermal conductivity and tunable dielectric loss characteristics. Even at high temperatures, its dielectric properties remain stable, contributing to long-lasting and reliable microwave absorption performance. Silica-coated carbonyl iron (average particle size 5 μm), as a magnetic loss filler, provides strong magnetic loss capability through its core. The crucial surface silica insulating coating ensures that the coating maintains extremely high volume resistivity even at high filler levels, fundamentally resolving the contradiction between microwave absorption and insulation performance.

[0032] Furthermore, this application employs a silane coupling agent to surface-treat all fillers, constructing a strong and tough chemical bond interface between the fillers and the organosilicon matrix. This interface not only effectively transfers stress and improves initial mechanical properties but also maintains structural integrity during subsequent high-temperature transformations, preventing coating cracking or peeling. It is well known that organosilicon materials subjected to prolonged high temperatures will experience irreversible hardening and embrittlement, considered an aging defect that limits their application in high-temperature structural components. This application, however, can actively utilize and guide this transformation process by precisely controlling the filler system and curing process. Specifically, after the material in this application is fully cured at a relatively low temperature (e.g., 200°C), the resulting coating already possesses excellent comprehensive properties. To cope with extreme environments, it can be further treated at high temperatures in an inert atmosphere, allowing for a controllable ceramization transformation of its surface. This allows for the active acquisition of ceramic-grade surface hardness, wear resistance, and ultra-high-temperature stability, while sacrificing a small amount of toughness.

[0033] Specifically, the application of the materials of this application in making a coating may include the following steps.

[0034] 1. Powder surface treatment: The mixture of silane coupling agent A151 and ethanol (volume ratio 1:1) was sprayed onto the insulating carbonyl iron powder using a sprayer, dispersed in a vacuum environment for 5 minutes using a high-speed disperser, and then dried in an oven at 80°C for 30 minutes before being taken out for use.

[0035] The mixture of silane coupling agent KH560 and ethanol (volume ratio 1:1) was sprayed onto flake boron nitride and alumina respectively using a sprayer. The mixture was then dispersed in a vacuum environment for 5 minutes using a high-speed disperser, followed by drying in an oven at 80°C for 30 minutes, and then taken out for use.

[0036] 2. Slurry preparation: According to the design ratio, vinyl silicone oil, hydrogen-containing silicone oil, catalyst, undecyltrimethoxysilane, and the treated filler are dispersed and mixed at high speed. After uniform dispersion, vacuum degassing is performed for 15 minutes.

[0037] 3. Coating and curing: Apply the slurry to the substrate and cure it according to the following procedure: 80°C / 1h -> 120°C / 1h -> 150°C / 1h -> 180°C / 2h -> 200°C / 4-6h, and then let it cool naturally.

[0038] Performance testing: Hardness (pencil hardness or nano-indentation), thermal conductivity, volume resistivity, and microwave absorption performance of the cured samples were measured. 4. Ceramization: Select the best sample, heat it to 900°C at 5°C / min under argon protection in a tube furnace, hold it at that temperature for 1 hour, and then cool it with the furnace.

[0039] The materials of this application will be further described in detail below through specific embodiments and comparative examples.

[0040] Example 1 (1) Powder surface treatment: 0.1% silane coupling agent (A151) and ethanol mixture (volume ratio 1:1) were sprayed onto the carbonyl iron powder with insulation coating using a sprayer. The mixture was dispersed at high speed (800r / min) for 5 min in a vacuum environment of a high-speed homogenizer, and then dried in an oven at 80℃ for 1 h before being taken out for use.

[0041] A mixture of 0.15% silane coupling agent (KH560) and ethanol (volume ratio 1:1) was sprayed onto flake boron nitride and alumina respectively using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment using a high-speed homogenizer at a rotation speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the mixture was taken out and set aside for later use.

[0042] (2) Slurry preparation: According to the mass fractions, 7.45 parts (200 cps) of vinyl silicone oil, 2.34 parts (15 cps) of hydrogen-containing silicone oil, 0.20 parts of coupling agent (ADS-001), 0.01 parts of platinum catalyst, 34.61 parts of surface-treated insulating coated carbonyl iron, 13.68 parts of surface-treated boron nitride, 26.38 parts of surface-treated alumina (particles of different sizes (average particle sizes of 40 μm and 1 μm) respectively), and 15.33 parts of silicon carbide were dispersed and mixed at high speed, and then vacuum degassed for 15 minutes after uniform dispersion.

[0043] (3) Coating and curing: Take a 5cm×5cm aluminum plate, use a scraper to evenly coat the slurry onto the substrate, and cure it in a vacuum drying oven according to the following procedure: 80°C / 1h -> 120°C / 1h -> 150°C / 1h -> 180°C / 2h -> 200°C / 4-6h, and then let it cool naturally.

[0044] (4) Performance testing: After curing, the adhesion, thermal conductivity, volume resistivity and reflection loss of the sample are tested.

[0045] Example 2 (1) Powder surface treatment: 0.1% silane coupling agent (A151) and ethanol mixture (volume ratio 1:1) were sprayed onto the carbonyl iron powder with insulation coating using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the powder was taken out for use.

[0046] A mixture of 0.15% silane coupling agent (KH560) and ethanol (volume ratio 1:1) was sprayed onto flake boron nitride and alumina using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After that, it was dried in an oven at 80℃ for 1 hour and then taken out for later use.

[0047] (2) Slurry preparation: According to the mass fractions, 7.45 parts (200 cps) of vinyl silicone oil, 2.34 parts (15 cps) of hydrogen-containing silicone oil, 0.20 parts of coupling agent (ADS-001), 0.01 parts of platinum catalyst, 24.61 parts of surface-treated insulating coated carbonyl iron, 13.68 parts of surface-treated boron nitride, 31.38 parts of surface-treated alumina (particles of different sizes (average particle sizes of 40 μm and 1 μm)), and 20.33 parts of silicon carbide were dispersed and mixed at high speed, and then vacuum degassed for 15 minutes after uniform dispersion.

[0048] (3) Coating and curing: Take a 5cm×5cm aluminum plate, take 2g of slurry and evenly coat it onto the substrate, and cure it in a vacuum drying oven according to the following procedure: 80°C / 1h -> 120°C / 1h -> 150°C / 1h -> 180°C / 2h -> 200°C / 4-6h, and then cool down naturally.

[0049] (4) Performance testing: After curing, the adhesion, thermal conductivity, volume resistivity and reflection loss of the sample are tested.

[0050] Example 3 (1) Powder surface treatment: 0.1% silane coupling agent (A151) and ethanol mixture (volume ratio 1:1) were sprayed onto the carbonyl iron powder with insulation coating using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the powder was taken out for use.

[0051] A mixture of 0.15% silane coupling agent (KH560) and ethanol (volume ratio 1:1) was sprayed onto flake boron nitride and alumina using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the mixture was ready for use.

[0052] (2) Slurry preparation: according to the following mass parts, 7.45 parts (200 cps) of vinyl silicone oil, 2.34 parts (15 cps) of hydrogen-containing silicone oil, 0.20 parts of coupling agent (ADS-001), 0.01 parts of platinum catalyst, 14.61 parts of surface-treated insulating coated carbonyl iron, 13.68 parts of surface-treated boron nitride, 36.38 parts of surface-treated alumina (particles of different sizes (average particle sizes of 40 μm and 1 μm)), and 25.33 parts of silicon carbide were dispersed and mixed at high speed, and then vacuum degassed for 15 minutes after uniform dispersion.

[0053] (3) Coating and curing: Take a 5cm×5cm aluminum plate, take 2g of slurry and evenly coat it onto the substrate, and cure it in a vacuum drying oven according to the following program: 80°C / 1h -> 120°C / 1h -> 150°C / 1h -> 180°C / 2h -> 200°C / 4-6h, and then let it cool down naturally.

[0054] (4) Performance testing: After curing, the adhesion, thermal conductivity, volume resistivity and reflection loss of the sample are tested.

[0055] Example 4 (1) Powder surface treatment: 0.1% silane coupling agent (A151) and ethanol mixture (volume ratio 1:1) were sprayed onto the carbonyl iron powder with insulation coating using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the powder was taken out for use.

[0056] A mixture of 0.15% silane coupling agent (KH560) and ethanol (volume ratio 1:1) was sprayed onto flake boron nitride and alumina using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the mixture was ready for use.

[0057] (2) Slurry preparation: according to the following mass parts, 7.45 parts (200 cps) of vinyl silicone oil, 2.34 parts (15 cps) of hydrogen-containing silicone oil, 0.20 parts of coupling agent (ADS-001), 0.01 parts of platinum catalyst, 14.61 parts of surface-treated insulating coated carbonyl iron, 13.68 parts of surface-treated boron nitride, 36.38 parts of surface-treated alumina (particles of different sizes (average particle sizes of 40 μm and 1 μm)), and 25.33 parts of silicon carbide were dispersed and mixed at high speed, and then vacuum degassed for 15 minutes after uniform dispersion.

[0058] (3) Coating and curing: Take a 5cm×5cm aluminum plate, take 2g of slurry and evenly coat it onto the substrate, and cure it in a vacuum drying phase: 80°C / 1h -> 120°C / 1h -> 150°C / 1h, and then let it cool down naturally.

[0059] (4) Performance testing: After curing, the adhesion, thermal conductivity, volume resistivity and reflection loss of the sample are tested.

[0060] Example 5 (1) Powder surface treatment: 0.1% silane coupling agent (A151) and ethanol mixture (volume ratio 1:1) were sprayed onto the carbonyl iron powder with insulation coating using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the powder was taken out for use.

[0061] A mixture of 0.15% silane coupling agent (KH560) and ethanol (volume ratio 1:1) was sprayed onto flake boron nitride and alumina using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the mixture was ready for use.

[0062] (2) Slurry preparation: according to the following mass parts, 7.45 parts (200 cps) of vinyl silicone oil, 2.34 parts (15 cps) of hydrogen-containing silicone oil, 0.20 parts of coupling agent (ADS-001), 0.01 parts of platinum catalyst, 14.61 parts of surface-treated insulating coated carbonyl iron, 13.68 parts of surface-treated boron nitride, 36.38 parts of surface-treated alumina (particles of different sizes (average particle sizes of 40 μm and 1 μm)), and 25.33 parts of silicon carbide were dispersed and mixed at high speed, and then vacuum degassed for 15 minutes after uniform dispersion.

[0063] (3) Coating and curing: Take a 5cm×5cm aluminum plate, take 2g of slurry and evenly coat it onto the substrate, and cure it in a vacuum drying phase: 80°C / 1h -> 120°C / 1h -> 150°C / 1h -> 180°C / 2h, and then let it cool down naturally.

[0064] (4) Performance testing: After curing, the adhesion, thermal conductivity, volume resistivity and reflection loss of the sample are tested.

[0065] Example 6 (1) Powder surface treatment: 0.1% silane coupling agent (A151) and ethanol mixture (volume ratio 1:1) were sprayed onto the carbonyl iron powder with insulation coating using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the powder was taken out for use.

[0066] A mixture of 0.15% silane coupling agent (KH560) and ethanol (volume ratio 1:1) was sprayed onto flake boron nitride and alumina using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the mixture was ready for use.

[0067] (2) Slurry preparation: according to the following mass parts, 7.45 parts (200 cps) of vinyl silicone oil, 2.34 parts (15 cps) of hydrogen-containing silicone oil, 0.20 parts of coupling agent (ADS-001), 0.01 parts of platinum catalyst, 14.61 parts of surface-treated insulating coated carbonyl iron, 13.68 parts of surface-treated boron nitride, 36.38 parts of surface-treated alumina (particles of different sizes (average particle sizes of 40 μm and 1 μm)), and 25.33 parts of silicon carbide were dispersed and mixed at high speed, and then vacuum degassed for 15 minutes after uniform dispersion.

[0068] (3) Coating and curing: Take a 5cm×5cm aluminum plate, apply 2g of slurry evenly to the substrate, and cure it in a vacuum drying oven according to the following program: 80°C / 1h -> 120°C / 1h -> 150°C / 1h -> 180°C / 2h -> 200°C / 4-6h, and then let it cool naturally. Then, under the protection of inert gas in a tube furnace, heat it to 900°C at a rate of 5°C / min, hold it at that temperature for 1h, and then cool it with the furnace.

[0069] (4) Performance testing: After curing, the adhesion, thermal conductivity, volume resistivity and reflection loss of the sample are tested.

[0070] Comparative Example 1 (1) Powder surface treatment: 0.1% silane coupling agent (A151) and ethanol mixture (volume ratio 1:1) were sprayed onto the uninsulated carbonyl iron powder using a sprayer. The powder was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the powder was taken out for use.

[0071] A mixture of 0.15% silane coupling agent (KH560) and ethanol (volume ratio 1:1) was sprayed onto flake boron nitride and alumina using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the mixture was ready for use.

[0072] (2) Slurry preparation: According to the mass fractions, 7.45 parts (200 cps) of vinyl silicone oil, 2.34 parts (15 cps) of hydrogen-containing silicone oil, 0.20 parts of coupling agent (ADS-001), 0.01 parts of platinum catalyst, 24.61 parts of uninsulated carbonyl iron powder, 13.68 parts of surface-treated boron nitride, 31.38 parts of surface-treated alumina (particles of different sizes (average particle sizes of 40 μm and 1 μm)), and 20.33 parts of silicon carbide were dispersed and mixed at high speed, and then vacuum degassed for 15 minutes after uniform dispersion.

[0073] (3) Coating and curing: Take a 5cm×5cm aluminum plate, take 2g of slurry and evenly coat it onto the substrate, and cure it in a vacuum drying oven according to the following procedure: 80°C / 1h -> 120°C / 1h -> 150°C / 1h -> 180°C / 2h -> 200°C / 4-6h, and then cool down naturally.

[0074] (4) Performance testing: After curing, the adhesion, thermal conductivity, volume resistivity and reflection loss of the sample are tested.

[0075] Comparative Example 2 (1) Powder surface treatment: 0.1% silane coupling agent (A151) and ethanol mixture (volume ratio 1:1) were sprayed onto the carbonyl iron powder with insulation coating using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the powder was taken out for use.

[0076] A mixture of 0.15% silane coupling agent (KH560) and ethanol (volume ratio 1:1) was sprayed onto flake boron nitride and alumina using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the mixture was ready for use.

[0077] (2) Slurry preparation: According to the mass fractions, 7.45 parts (200 cps) of vinyl silicone oil, 2.34 parts (15 cps) of hydrogen-containing silicone oil, 0.20 parts of coupling agent (ADS-001), 0.01 parts of platinum catalyst, 24.61 parts of surface-treated insulating coated carbonyl iron, 13.68 parts of surface-treated boron nitride, 31.38 parts of surface-treated alumina (particles of different sizes (average particle sizes of 40 μm and 1 μm)), and 20.33 parts of silicon carbide were dispersed and mixed at high speed, and then vacuum degassed for 15 minutes after uniform dispersion.

[0078] (3) Coating and curing: Take a 5cm×5cm aluminum plate, take 2g of slurry and evenly coat it onto the substrate, cure it directly in a vacuum drying phase at 200℃, and then cool it naturally.

[0079] (4) Performance testing: After curing, the adhesion, thermal conductivity, volume resistivity and reflection loss of the sample are tested.

[0080] Comparative Example 3 (1) Powder surface treatment: The powder ratio of 0.15% silane coupling agent (KH560) and ethanol mixture (volume ratio 1:1) was sprayed onto the flake boron nitride and alumina respectively using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the powder was taken out for use.

[0081] (2) Slurry preparation: according to the following mass parts, 7.45 parts (200 cps) of vinyl silicone oil, 2.34 parts (15 cps) of hydrogen-containing silicone oil, 0.20 parts of coupling agent (ADS-001), 0.01 parts of platinum catalyst, 25.99 parts of surface-treated boron nitride, 43.68 parts of surface-treated alumina (particles of different sizes (average particle sizes of 40 μm and 1 μm respectively), and 20.33 parts of silicon carbide were dispersed and mixed at high speed, and then vacuum degassed for 15 minutes after uniform dispersion.

[0082] (3) Coating and curing: Take a 5cm×5cm aluminum plate, take 2g of slurry and evenly coat it onto the substrate, and cure it in a vacuum drying oven according to the following procedure: 80°C / 1h -> 120°C / 1h -> 150°C / 1h -> 180°C / 2h -> 200°C / 4-6h, and then cool down naturally.

[0083] (4) Performance testing: After curing, the adhesion, thermal conductivity, volume resistivity and reflection loss of the sample are tested.

[0084] Comparative Example 4 (1) Powder surface treatment: 0.1% silane coupling agent (A151) and ethanol mixture (volume ratio 1:1) were sprayed onto the carbonyl iron powder with insulation coating using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the powder was taken out for use.

[0085] (2) Slurry preparation: According to the mass fractions, 7.45 parts (200 cps) of vinyl silicone oil, 2.34 parts (15 cps) of hydrogen-containing silicone oil, 0.20 parts of coupling agent (ADS-001), 0.01 parts of platinum catalyst, 49.23 parts of surface-treated insulating coated carbonyl iron, and 40.72 parts of silicon carbide were dispersed and mixed at high speed. After uniform dispersion, vacuum degassing was performed for 15 minutes.

[0086] (3) Coating and curing: Take a 5cm×5cm aluminum plate, take 2g of slurry and evenly coat it onto the substrate, and cure it in a vacuum drying oven according to the following procedure: 80°C / 1h -> 120°C / 1h -> 150°C / 1h -> 180°C / 2h -> 200°C / 4-6h, and then cool down naturally.

[0087] (4) Performance testing: After curing, the adhesion, thermal conductivity, volume resistivity and reflection loss of the sample are tested.

[0088] Comparative Example 5 (1) Powder surface treatment: 0.1% silane coupling agent (A151) and ethanol mixture (volume ratio 1:1) were sprayed onto the carbonyl iron powder with insulation coating using a sprayer. The mixture was then dispersed at high speed for 5 minutes in a vacuum environment at a speed of 800 r / min. After drying in an oven at 80℃ for 1 hour, the powder was taken out for use.

[0089] 2) Slurry preparation: According to the mass fraction, 7.45 parts (200 cps) of vinyl silicone oil, 2.34 parts (15 cps) of hydrogen-containing silicone oil, 0.20 parts of coupling agent (ADS-001), 0.01 parts of platinum catalyst, and 80 parts of surface-treated insulating coated carbonyl iron are dispersed and mixed at high speed. After uniform dispersion, vacuum degassing is performed for 15 minutes.

[0090] (3) Coating and curing: Take a 5cm×5cm aluminum plate, take 2g of slurry and evenly coat it onto the substrate, and cure it in a vacuum drying oven according to the following procedure: 80°C / 1h -> 120°C / 1h -> 150°C / 1h -> 180°C / 2h -> 200°C / 4-6h, and then cool down naturally.

[0091] (4) Performance testing: After curing, the adhesion, thermal conductivity, volume resistivity and reflection loss of the sample are tested.

[0092] The coatings obtained in Examples 1-5 and Comparative Examples 1-5 were subjected to performance tests. The specific test methods are as follows: I. Test Method for Reflection Loss According to the People's Republic of China National Standard GB / T32596-2016 - General Specification for Electromagnetic Shielding Absorbers, the absorption performance of the absorbers was tested using a Keysight Technologies (China) Co., Ltd. E5080B network analyzer (100kHz-44GHz) and transmission lines. Details are as follows.

[0093] 1. Prepare test samples.

[0094] 1.1 Coaxial transmission line test The test sample is a concentric ring-shaped specimen.

[0095] The outer diameter is 6.95-7.00mm, the inner diameter is 3.05-3.10mm, and the concentricity deviation is less than 0.1mm.

[0096] 1.2 The waveguide transmission line sample is a rectangular specimen.

[0097] The length is ±0.05mm of the basic width of the waveguide inner section, and the height is ±0.05mm of the basic height of the waveguide inner section.

[0098] 2. Use SOLT to calibrate the vector network analyzer.

[0099] 3. Place the prepared sample into the test fixture for testing. After placement, the sample surface should be perpendicular to the incident direction of the electromagnetic wave and should not be bent or tilted. The S-parameters are then obtained.

[0100] 4. Process and plot the test data. Specifically, as follows: Figure 1-4 As shown.

[0101] II. Volume Resistivity Test The volume resistivity of the material was tested according to the People's Republic of China National Standard GB / T 1410-2006 "Test Methods for Volume Resistivity and Surface Resistivity of Solid Insulating Materials".

[0102] III. Adhesion Test According to the People's Republic of China National Standard GB / T 9286-2021 "Cross-cut Test for Paints and Varnishes", the adhesion of the material was tested by applying a 150μm coating to an aluminum plate with a scraper. After high-temperature curing using the above process, the prepared sample was cut into 25 squares at 3 mm intervals with a single-edged cutter. 3M#600 tape was used to test its adhesion level.

[0103] IV. Thermal conductivity test According to the People's Republic of China National Standard GB / T 32064-2015 "Temperature Test Method for Thermal Conductivity and Thermal Diffusion Coefficient of Building Materials by Transient Plane Heat Source", the thermal conductivity of the material is tested by solidifying the slurry in a mold (2cm×5cm) at high temperature according to the test temperature, and then stacking it (>5cm) to test its thermal conductivity.

[0104] The test results are analyzed in detail below.

[0105] pass Figures 1 to 3 It can be seen that the samples made from the materials of this application have excellent wave absorption performance.

[0106] As shown in Table 1, the samples from Examples 1 to 3 exhibit high thermal conductivity. Comparative Example 3 shows the highest thermal conductivity, likely due to the highest total amount of boron nitride and alumina added. This demonstrates that in the material system of this application, spherical alumina serves as the basic thermally conductive filler. Its particles of different sizes (average particle sizes of 40 μm and 1 μm, respectively) can achieve close packing, effectively filling the resin matrix and constructing a three-dimensional thermally conductive framework. This complements the plate-like boron nitride spatially, jointly improving the thermal conductivity and structural stability of the coating. Furthermore, Comparative Example 5 also shows that without the addition of silicon carbide, the thermal conductivity is significantly reduced, indicating that silicon carbide is beneficial for improving thermal conductivity in the system of this application.

[0107] Table 1: Thermal conductivity test

[0108] As shown in Table 2, the samples in Examples 1 to 3 exhibit very high volume resistivity. This is because the silica-coated carbonyl iron (average particle size of 5 μm) acts as a magnetic loss-generating filler, with its core providing strong magnetic loss capability. The crucial surface silica insulating coating ensures that the coating maintains extremely high volume resistivity even at high filler levels, fundamentally resolving the contradiction between absorption and insulation performance. Comparative Example 1, due to the use of uncoated carbonyl iron, shows a significant decrease in volume resistivity. Examples 1-3 demonstrate that the synergistic effect of the insulating carbonyl iron coating with boron nitride and aluminum oxide can significantly improve volume resistivity.

[0109] Table 2: Volume Resistivity

[0110] As shown in Table 3, due to the different curing procedures, the adhesion performance of samples from Examples 1 to 3 was significantly better than that of samples from Examples 4, 5, and Comparative Example 2. In Comparative Example 2, the samples were directly cured in a vacuum-dried phase at 200°C, followed by natural cooling. In Example 4, the curing procedure in the vacuum-dried phase was: 80°C / 1h -> 120°C / 1h -> 150°C / 1h, followed by natural cooling. In Example 5, the curing procedure in the vacuum-dried phase was: 80°C / 1h -> 120°C / 1h -> 150°C / 1h -> 180°C / 2h, followed by natural cooling. Examples 1 to 3 were all cured in a vacuum drying oven using the following procedure: 80°C / 1h -> 120°C / 1h -> 150°C / 1h -> 180°C / 2h -> 200°C / 4-6h, followed by natural cooling.

[0111] Table 3: Adhesion Performance Test The rating is ASTM grade 5B-0B.

[0112] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0113] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A thermally conductive and microwave-absorbing coating based on an organosilicon precursor, characterized in that, By weight, it includes: Vinyl silicone oil, 5-15 parts; Hydrogen-containing silicone oil, 2-5 parts; Coupling agent, 0.16-0.5 parts; Catalyst, 0.01-0.02 parts; Surface-treated insulating carbonyl iron, 10-40 parts; Surface-treated boron nitride, 5-15 parts; Surface-treated alumina, 10-30 parts; Silicon carbide, 10-20 parts.

2. The thermally conductive and microwave-absorbing coating based on an organosilicon precursor according to claim 1, characterized in that, The surface-treated insulating carbonyl iron comprises: a mixture of silane coupling agent and ethanol sprayed onto insulating carbonyl iron powder, dispersed at high speed under vacuum, and then dried.

3. The thermally conductive and microwave-absorbing coating based on an organosilicon precursor according to claim 1, characterized in that, The surface-treated boron nitride comprises: a mixture of silane coupling agent and ethanol sprayed onto sheet-like boron nitride, dispersed under vacuum, and then dried.

4. The thermally conductive and microwave-absorbing coating based on an organosilicon precursor according to claim 3, characterized in that, The surface-treated alumina comprises: a mixture of silane coupling agent and ethanol sprayed onto spherical alumina, dispersed under vacuum, and then dried.

5. The thermally conductive and microwave-absorbing coating based on an organosilicon precursor according to claim 4, characterized in that, The average diameter of the plate-shaped boron nitride is 30 μm, while the spherical alumina has two average particle sizes, 40 μm and 1 μm.

6. The thermally conductive and microwave-absorbing coating based on an organosilicon precursor according to claim 1, characterized in that, Vinyl silicone oil with a viscosity of 200~500 cps and hydrogen-containing silicone oil with a viscosity of 10~90 cps constitute an addition-curing system.

7. The thermally conductive and microwave-absorbing coating based on an organosilicon precursor according to claim 1, characterized in that, The silicon carbide has an average particle size of 40 μm, and the surface-treated insulating carbonyl iron has an average particle size of 5 μm.

8. The thermally conductive and microwave-absorbing coating based on an organosilicon precursor according to claim 1, characterized in that, The coupling agent includes at least one of the following: silane coupling agent KH550, silane coupling agent KH560, silane coupling agent A-151, silane coupling agent trimethoxy-n-octylsilane, silane coupling agent trimethoxy-n-decane, silane coupling agent KH560, silane coupling agent hexadecyltriethoxysilane, and silane coupling agent hexadecyltrimethoxysiloxane.

9. A method for preparing a thermally conductive and microwave-absorbing coating based on an organosilicon precursor, characterized in that, The thermally conductive and microwave-absorbing coating based on an organosilicon precursor, as described in any one of claims 1 to 8, is achieved by first mixing the various components in proportion, uniformly dispersing them, and then vacuum degassing. Then a curing process is performed, which includes: holding at 80°C for 1 hour, then at 120°C for 1 hour, then at 150°C for 1 hour, then at 180°C for 2 hours, then at 200°C for 4-6 hours, followed by natural cooling.

10. A method for preparing a thermally conductive and microwave-absorbing ceramic coating based on an organosilicon precursor, characterized in that, The thermally conductive and microwave-absorbing coating based on an organosilicon precursor, as described in any one of claims 1 to 8, is achieved by first mixing the various components in proportion, uniformly dispersing them, and then vacuum degassing. Then a curing process is performed, which includes: holding at 80°C for 1 hour, then at 120°C for 1 hour, then at 150°C for 1 hour, then at 180°C for 2 hours, then at 200°C for 4-6 hours, followed by natural cooling, and then, under the protection of inert gas in a tube furnace, the temperature is increased to 900°C at a rate of 5°C / min, then held for 1 hour, and then cooled with the furnace.

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