Self-repairing high lightning strike resistant carbon fiber composite material and preparation method thereof

Abstract

The application discloses a self-repairing high lightning-resistant carbon fiber composite material, which is laid from top to bottom by a self-repairing conductive layer, an insulating heat-conducting layer and a carbon fiber base layer; the self-repairing conductive layer comprises a resin matrix and a composite conductive network dispersed in the resin matrix, the composite conductive network is composed of carbon nanotubes densely filled with gallium-based liquid metal droplets and expanded graphite; the insulating heat-conducting layer is made by uniformly mixing honeycomb-like hexagonal boron nitride and resin; and the carbon fiber base layer is made by laminating and laying 32 layers of carbon fiber and epoxy resin prepreg, the first 6 layers are uniformly laid with vertical short-cut carbon fibers, and the carbon fibers extend upward and penetrate through the insulating heat-conducting layer. The self-repairing high lightning-resistant carbon fiber composite material and the preparation method solve the problems that the existing composite material cannot be repaired and cannot realize continuous and effective protection under multiple lightning strikes after being struck by lightning.

Description

Technical Field

[0001] This invention belongs to the field of aerospace composite materials technology, specifically relating to self-healing high lightning strike resistant carbon fiber composite materials. This invention also relates to a method for preparing self-healing high lightning strike resistant carbon fiber composite materials. Background Technology

[0002] Carbon fiber reinforced composites are widely used in the aerospace field due to their advantages such as high strength, corrosion resistance, light weight, and high designability. However, compared with traditional metal materials, the lower electrical and thermal conductivity of composite materials makes it difficult for them to transfer and dissipate the large amount of accumulated charge and heat in a short time when struck by lightning. This causes a sharp rise in temperature in the lightning strike area, resulting in serious damage such as resin pyrolysis, fiber breakage, and interlayer delamination, which threatens the flight safety of aircraft.

[0003] To address the aforementioned issues, lightning protection research has received increasing attention. Existing lightning protection technologies mainly include surface conduction and internal material modification techniques. Surface conduction technology involves applying highly conductive layers such as aluminum or silver mesh / foil, or graphite or carbon nanotube coatings to the surface of composite materials. This accelerates the conduction of lightning current along the in-surface direction, allowing for rapid energy release in the lightning arc attachment area and suppressing lightning-induced surface damage. Internal material modification technology involves doping the epoxy resin within the composite material with conductive fillers such as carbon black or buckypaper to enhance the material's internal conductivity, accelerating lightning current conduction within the composite material and suppressing internal ablation and delamination damage caused by lightning strikes. All of these lightning protection technologies rely on pre-constructed highly conductive paths to accelerate lightning current conduction, inevitably leading to localized ablation and breakage of these highly conductive paths. This results in irreversible degradation of the composite material's lightning resistance, making it impossible to achieve effective protection against multiple lightning strikes. Summary of the Invention

[0004] The first objective of this invention is to provide a self-healing, highly lightning-resistant carbon fiber composite material. Based on the synergistic effect of the self-healing conductive layer, the insulating and thermally conductive layer, and the carbon fiber substrate, it effectively suppresses the adhesion damage and internal conduction damage to the surface of the composite material caused by lightning strikes, thus solving the problem that the conductive network of existing composite materials cannot be repaired after being struck by lightning and cannot achieve continuous and effective protection under multiple lightning strikes.

[0005] The second objective of this invention is to provide a method for preparing a self-healing, highly lightning-resistant carbon fiber composite material.

[0006] The first technical solution adopted in this invention is a self-healing high lightning strike resistant carbon fiber composite material, comprising a self-healing conductive layer, an insulating and thermally conductive layer and a carbon fiber base layer, wherein the self-healing conductive layer, the insulating and thermally conductive layer and the carbon fiber base layer are laid from top to bottom. The self-healing conductive layer comprises a resin matrix and a composite conductive network dispersed in the resin matrix. The composite conductive network is composed of carbon nanotubes densely filled with gallium-based liquid metal droplets and expanded graphite. The insulating and thermally conductive layer is made of honeycomb hexagonal boron nitride and resin uniformly mixed. The carbon fiber substrate layer is made of 32 layers of carbon fiber and epoxy resin prepreg, with the first 6 layers uniformly laid with vertically chopped carbon fibers that extend upwards through the insulating and thermally conductive layer.

[0007] The first technical solution of this invention is also characterized in that, The thickness of the self-healing conductive layer is 0.02mm-0.30mm, and the thickness of the insulating and thermally conductive layer is 0.02mm-0.30mm.

[0008] In the self-healing conductive layer, the mass ratio of carbon nanotubes to expanded graphite is 1:(1-5), and the total amount of carbon nanotubes and expanded graphite added is 3wt%-20wt% of the resin matrix mass; the gallium-based liquid metal droplets are eutectic gallium-indium alloys, and the volume fraction of eutectic gallium-indium alloys accounts for 5%-35% of the total volume of the self-healing conductive layer, with an average particle size of 1μm-100μm; in the insulating and thermally conductive layer, the honeycomb hexagonal boron nitride has a particle size of 1μm-10μm, and the amount of hexagonal boron nitride added is 10wt%-50wt% of the resin mass in the insulating and thermally conductive layer.

[0009] The vertically chopped carbon fibers have a length of 0.2mm-2mm and a diameter of 5μm-10μm.

[0010] The second technical solution adopted in this invention is a method for preparing a self-healing, high lightning strike resistant carbon fiber composite laminate, using the aforementioned self-healing, high lightning strike resistant carbon fiber composite material, comprising the following steps: S1. Cut the prepreg and lay it out, and insert vertically chopped carbon fibers into the top 1-6 layers to form a carbon fiber base layer prefabricated structure; S2. Prepare the insulating and thermally conductive layer paste; S3. Prepare a self-healing conductive layer slurry; S4. On the upper surface of the carbon fiber substrate, the insulating and thermally conductive layer slurry and the self-healing conductive layer slurry are coated sequentially by scraping to form a preform stacked structure. S5. Vacuum bag encapsulation of the preform stack structure and curing molding. After curing, demolding and trimming are performed to obtain self-healing high lightning strike resistant carbon fiber composite material.

[0011] The second technical solution of the present invention is further characterized in that, The specific steps of S1 are as follows: cut carbon fiber and epoxy resin prepreg, lay them up according to the preset layup sequence, and during the laying of the top 1-6 layers, after laying one or two layers of prepreg, evenly insert vertically chopped carbon fiber into the surface of the currently laid top layer of prepreg, so that the vertically chopped carbon fiber is oriented along the thickness direction and partially embedded in the layer of prepreg. Control the volume fraction of vertically chopped carbon fiber to be 0.5%-8% of the volume of the resin in the interlayer. Then continue to lay the next layer of prepreg until the carbon fiber base layer prefabricated structure is formed.

[0012] The preparation of the insulating and thermally conductive layer paste in S2 includes the following steps: S2.1, Take epoxy resin and adjust its viscosity to be within the range of 1000cps-5000cps; add hexagonal boron nitride powder with a particle size of 1μm-10μm to the resin, the amount of which is 10wt%-50wt% of the resin mass; S2.2, honeycomb hexagonal boron nitride powder with a particle size of 1μm-10μm is added to the resin matrix, and the amount of hexagonal boron nitride powder added is 10wt%-50wt% of the resin matrix mass; mechanical stirring is performed at a speed of 300rpm-1500rpm for 15min-30min, and ultrasonic dispersion is performed at a power of 100W-500W for 10min-40min to uniformly disperse the hexagonal boron nitride in the resin matrix; then degassing is performed under vacuum conditions of -0.06MPa to -0.10MPa for 10min-30min to obtain the insulating and thermally conductive layer slurry.

[0013] S3 specifically includes the following steps: Step 1: Disperse carbon nanotubes and expanded graphite in a resin matrix, mechanically stir at 500 rpm-2000 rpm, and ultrasonically disperse at 100 W-500 W for 10 min-60 min to form a uniform composite conductive network slurry. Step 2: The carbon nanotubes and expanded graphite in the composite conductive network slurry obtained in Step 1 are surface activated by plasma treatment. Step 3: After activation treatment, gallium-based liquid metal microdroplets are introduced into the composite conductive network slurry to obtain a uniformly mixed slurry; Step 4: Place the uniformly mixed slurry obtained in Step 3 into a sealed container for pressure impregnation treatment. First, evacuate to a relative vacuum of 0.08MPa-0.1MPa to remove gas. Then, maintain the pressure at 0.2MPa-0.5MPa for 5min-20min to allow the liquid metal to fully impregnate and fill the conductive network pore structure. Then, release the pressure to atmospheric pressure.

[0014] Step 3 introduces gallium-based liquid metal microdroplets using a combination of vacuum-assisted infiltration and mechanical stirring. The specific steps are as follows: The composite conductive network slurry is placed in a sealable stirring container, and a vacuum is drawn to -0.08 MPa to -0.10 MPa, maintained for 5-10 minutes to remove air bubbles trapped in the slurry. The negative pressure environment allows the resin matrix to fully wet the filler surface. Nitrogen gas is then introduced into the stirring container and pressurized to 0.2 MPa to 0.5 MPa. Under this pressure, liquid metal is slowly injected into the slurry at a predetermined volume fraction using a micro-injection pump, with the droplet rate controlled at 1 mL / min to 3 mL / min. At a temperature controlled at 25℃ to 30℃, low-speed stirring is performed at 200 rpm to 800 rpm for 5-30 minutes, ensuring the liquid metal is uniformly dispersed in the slurry as microdroplets with an average particle size of 1 μm to 100 μm.

[0015] The specific steps of S5 are as follows: After completing the preform stacking structure, vacuum bag sealing is performed, and the vacuum degree is controlled to -0.06MPa to -0.10MPa, followed by curing and molding; the curing and molding process is divided into three stages. The first stage involves heating to 80℃-100℃ at a rate of 1℃ / min-5℃ / min and holding at that temperature for 20min-60min. During this stage, the vacuum level is maintained at -0.09MPa and the pressure in the autoclave is 0MPa at atmospheric pressure. In the second stage, the temperature is increased to 120℃-160℃ at a heating rate of 2.0℃ / min, and then held at that temperature for 2.0h under the condition that the pressure in the autoclave is increased to 0.5-0.7MPa. In the third stage, the temperature is further increased to 120℃-180℃, and the temperature is maintained at 0.5MPa for 50-80 minutes to complete the final curing. After curing, the pressure is maintained and the furnace is allowed to cool naturally to below 55°C at a rate not exceeding 3°C / min. Then, the pressure is released, the vacuum is broken, and the mold is removed and trimmed to obtain a self-healing high lightning strike resistant carbon fiber composite material.

[0016] The beneficial effects of this invention are: (1) The self-healing high lightning-resistant carbon fiber composite laminate and its preparation method provided by the present invention are characterized by a self-healing conductive layer composed of a composite conductive network consisting of carbon nanotubes densely filled with gallium-based liquid metal droplets and expanded graphite. When lightning strikes, the oxide film on the surface of the liquid metal droplets ruptures due to heat, and the liquid metal droplets flow out and are adsorbed by the conductive network to fill the lightning strike damage breakpoint, thus repairing the conductive network in real time. The dynamic reconstruction bridging of the droplet-conductive network accelerates the conduction of lightning current in the plane and inhibits lightning-attached damage. After the lightning strike, the liquid metal droplets re-solidify and oxidize, and flow out again to fill the damage breakpoint during subsequent lightning strikes, realizing repeated self-repair of the conductive network.

[0017] (2) The self-healing high lightning resistance carbon fiber composite laminate and preparation method provided by the present invention have an insulating and thermally conductive layer composed of honeycomb hexagonal boron nitride and resin uniformly mixed to form a laminate. By utilizing the anisotropic thermal conductivity of hexagonal boron nitride, the lightning Joule heat and adhesion heat accumulated in the self-healing conductive layer are rapidly diffused along the surface, thereby suppressing their thermal damage to the carbon fiber substrate.

[0018] (3) The self-healing high lightning resistance carbon fiber composite laminate and preparation method provided by the present invention are made of carbon fiber and epoxy resin prepreg in 32 layers. The first 6 layers are uniformly laid with vertically chopped carbon fibers, which extend upward and penetrate through the insulating and heat-conducting layer, so that the residual lightning current in the self-healing conductive layer is rapidly dispersed and conducted along the thickness direction, thereby suppressing the conductive thermal damage to the interior of the composite material caused by lightning strike. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the preparation process of the self-healing high lightning strike resistant carbon fiber composite material of the present invention. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0021] The self-healing high lightning strike resistant carbon fiber composite material provided by the present invention includes a self-healing conductive layer, an insulating and thermally conductive layer and a carbon fiber base layer, wherein the self-healing conductive layer, the insulating and thermally conductive layer and the carbon fiber base layer are laid from top to bottom. The self-healing conductive layer comprises a resin matrix and a composite conductive network dispersed in the resin matrix. The composite conductive network is composed of carbon nanotubes densely filled with gallium-based liquid metal droplets and expanded graphite. The insulating and thermally conductive layer is made of honeycomb hexagonal boron nitride and resin uniformly mixed. The carbon fiber substrate layer is made of 32 layers of carbon fiber and epoxy resin prepreg. The first 6 layers are uniformly covered with vertically chopped carbon fibers, which extend upwards and penetrate through the insulating and thermally conductive layer. The vertically chopped carbon fibers have a length of 0.2mm-2mm and a diameter of 5μm-10μm. The vertically chopped carbon fibers are placed between the top 1-6 layers of the carbon fiber substrate layer.

[0022] The self-healing conductive layer has a thickness of 0.02mm-0.30mm, and the insulating and thermally conductive layer has a thickness of 0.02mm-0.30mm. In the self-healing conductive layer, the mass ratio of carbon nanotubes to expanded graphite is 1:(1-5), and the total addition amount of carbon nanotubes and expanded graphite is 3wt%-20wt% of the resin matrix mass. The gallium-based liquid metal droplets are eutectic gallium-indium alloys, with the volume fraction of the eutectic gallium-indium alloy accounting for 5%-35% of the total volume of the self-healing conductive layer, and an average particle size of 1μm-100μm. In the insulating and thermally conductive layer, the honeycomb-shaped hexagonal boron nitride has a particle size of 1μm-10μm, and the addition amount of hexagonal boron nitride is 10wt%-50wt% of the resin mass in the insulating and thermally conductive layer.

[0023] This invention also provides a method for preparing the above-mentioned self-healing, highly lightning-resistant carbon fiber composite material, such as... Figure 1 As shown, please follow these steps: S1. Cut the prepreg and lay it out, and insert vertically chopped carbon fibers into the top 1-6 layers to form a carbon fiber base layer prefabricated structure; The specific steps of S1 are as follows: cut carbon fiber or epoxy resin prepreg and lay it according to the preset layup sequence. During the laying of the top 1-6 layers, after each layer or every two layers of prepreg, vertically chopped carbon fibers are evenly implanted into the surface of the currently laid top layer of prepreg, so that the vertically chopped carbon fibers are oriented along the thickness direction and partially embedded in the layer of prepreg. The volume fraction of vertically chopped carbon fibers is controlled to be 0.5%-8% of the volume of the resin in the interlayer. Then continue to lay the next layer of prepreg until the carbon fiber base layer prefabricated structure is formed.

[0024] S2. Prepare the insulating and thermally conductive layer paste; The preparation of the insulating and thermally conductive layer paste in S2 includes the following steps: S2.1, Take epoxy resin and adjust its viscosity to be within the range of 1000cps-5000cps; add hexagonal boron nitride powder with a particle size of 1μm-10μm to the resin, the amount of which is 10wt%-50wt% of the resin mass; S2.2, honeycomb hexagonal boron nitride powder with a particle size of 1μm-10μm is added to the resin matrix. The amount of hexagonal boron nitride powder added is 10wt%-50wt% of the resin matrix mass. The mixture is mechanically stirred at a speed of 300rpm-1500rpm for 15min-30min and ultrasonically dispersed at a power of 100W-500W for 10min-40min to ensure that the hexagonal boron nitride is uniformly dispersed in the resin matrix. Then, the mixture is degassed under a vacuum of -0.06MPa to -0.10MPa for 10min-30min to obtain an insulating and thermally conductive slurry. The obtained slurry is sealed and stored for later use.

[0025] S3. Prepare a self-healing conductive layer slurry; S3 specifically includes the following steps: Step 1: Disperse carbon nanotubes and expanded graphite in a resin matrix, mechanically stir at 500 rpm-2000 rpm, and ultrasonically disperse at 100 W-500 W for 10 min-60 min to form a uniform composite conductive network slurry. Step 2: The carbon nanotubes and expanded graphite in the composite conductive network slurry obtained in Step 1 are surface activated by plasma treatment. Step 3: After activation treatment, gallium-based liquid metal microdroplets are introduced into the composite conductive network slurry to obtain a uniformly mixed slurry; Step 3 introduces gallium-based liquid metal microdroplets using a combination of vacuum-assisted infiltration and mechanical stirring. The specific steps are as follows: The composite conductive network slurry is placed in a sealable stirring container, and a vacuum is drawn to -0.08 MPa to -0.10 MPa, maintained for 5-10 minutes to remove air bubbles trapped in the slurry. The negative pressure environment allows the resin matrix to fully wet the filler surface. Nitrogen gas is then introduced into the stirring container and pressurized to 0.2 MPa to 0.5 MPa. Under this pressure, liquid metal is slowly injected into the slurry at a predetermined volume fraction using a micro-injection pump, with the droplet rate controlled at 1 mL / min to 3 mL / min. At a temperature controlled at 25℃ to 30℃, low-speed stirring is performed at 200 rpm to 800 rpm for 5-30 minutes, ensuring the liquid metal is uniformly dispersed in the slurry as microdroplets with an average particle size of 1 μm to 100 μm.

[0026] Step 4: Place the uniformly mixed slurry obtained in Step 3 into a sealed container for pressure impregnation treatment. First, evacuate to a relative vacuum of 0.08MPa-0.1MPa to remove gas. Then, maintain the pressure at 0.2MPa-0.5MPa for 5min-20min to allow the liquid metal to fully impregnate and fill the conductive network pore structure. Then, release the pressure to atmospheric pressure.

[0027] S4. On the upper surface of the carbon fiber substrate, the insulating and thermally conductive layer slurry and the self-healing conductive layer slurry are coated sequentially by scraping to form a preform stacked structure. S5. Vacuum bag encapsulation of the preform stack structure and curing molding. After curing, demolding and trimming are performed to obtain self-healing high lightning strike resistant carbon fiber composite material.

[0028] The specific steps of S5 are as follows: After completing the preform stacking structure, vacuum bag sealing is performed, and the vacuum degree is controlled to -0.06MPa to -0.10MPa. Then, it is placed in an autoclave for curing and molding. The curing and molding process is divided into three stages. The first stage involves heating to 80℃-100℃ at a rate of 1℃ / min-5℃ / min and holding at that temperature for 20min-60min. During this stage, the vacuum level is maintained at -0.09MPa and the pressure in the autoclave is 0MPa at atmospheric pressure. In the second stage, the temperature is increased to 120℃-160℃ at a heating rate of 2.0℃ / min, and then held at that temperature for 2.0h under the condition that the pressure in the autoclave is increased to 0.5-0.7MPa. In the third stage, the temperature is further increased to 120℃-180℃, and the temperature is maintained at 0.5MPa for 50-80 minutes to complete the final curing. After curing, the pressure is maintained and the furnace is allowed to cool naturally to below 55°C at a rate not exceeding 3°C / min. Then, the pressure is released, the vacuum is broken, and the mold is removed and trimmed to obtain a self-healing high lightning strike resistant carbon fiber composite material.

[0029] Example 1 This embodiment provides a method for preparing a self-healing, highly lightning-resistant carbon fiber composite laminate, specifically including the following steps: S1. Cut a prepreg made of IM600 carbon fiber and JT1312 epoxy resin system, lay it up according to the preset layup sequence, and cut it to make a 150mm×100mm×4mm laminate sample with a total of 32 layers. The layup direction is [45° / 0° / -45° / 90°]. 4S During the laying of the top 1-6 layers, after every two layers of prepreg, vertically chopped carbon fibers are evenly implanted into the surface of the currently laid top layer of prepreg, so that the vertically chopped carbon fibers are oriented along the thickness direction and partially embedded in the prepreg layer. The vertically chopped carbon fibers have a length of 0.2 mm and a diameter of 5 μm, and the volume fraction of the vertically chopped carbon fibers is controlled to be 0.5% of the volume of the resin in the interlayer. Then, the next layer of prepreg is laid until the carbon fiber base layer prefabricated structure is formed.

[0030] The ambient temperature for laying the equipment should be controlled between 18℃ and 28℃, and the relative humidity should be controlled between 40% and 60%.

[0031] S2. Preparation of the insulating and thermally conductive layer paste, including the following steps: S2.1 Take epoxy resin and adjust its viscosity to 1000 cps. Add honeycomb hexagonal boron nitride powder with a particle size of 1 μm to the resin at a rate of 10 wt% of the resin mass.

[0032] S2.2 was mechanically stirred at 300 rpm for 30 min and then ultrasonically dispersed at 100 W for 40 min to uniformly disperse hexagonal boron nitride in the resin matrix; then degassed under a vacuum of -0.10 MPa for 30 min to obtain the insulating and thermally conductive layer slurry.

[0033] S3. Preparation of self-healing conductive layer slurry, including the following steps: Step 1: Carbon nanotubes and expanded graphite are dispersed in a resin matrix. The carbon nanotubes have a diameter of 20 nm and a length of 15 μm. The expanded graphite has a thickness of 70 nm and a length of 15 μm. The mass ratio of carbon nanotubes to expanded graphite is 1:1, and the total amount of carbon nanotubes and expanded graphite added is 3 wt% of the resin matrix mass. The mixture is mechanically stirred at 500 rpm and ultrasonically dispersed at 100 W for 60 min to form a uniform composite conductive network slurry.

[0034] Step 2: The carbon nanotubes and expanded graphite in the composite conductive network slurry obtained in Step 1 are surface activated by low-temperature oxygen plasma treatment. The treatment power is 55W and the treatment time is 4min.

[0035] Step 3: After activation treatment, gallium-based liquid metal microdroplets are introduced into the composite conductive network slurry to obtain a uniformly mixed slurry. The gallium-based liquid metal microdroplets are eutectic gallium-indium alloys, in which the mass ratio of gallium to indium is 75.5:24.5, and the volume fraction of the gallium-based liquid metal microdroplets accounts for 5% of the total volume of the self-healing conductive layer.

[0036] The introduction of gallium-based liquid metal microdroplets employs a combination of vacuum-assisted infiltration and mechanical stirring. Specifically, the composite conductive network slurry is placed in a sealable stirring container, and a vacuum is drawn to -0.08 MPa and maintained for 10 minutes to remove air bubbles trapped in the slurry. The negative pressure environment allows the resin matrix to fully wet the filler surface. Subsequently, nitrogen gas is introduced into the stirring container to pressurize it to 0.2 MPa. Under pressurized conditions, liquid metal is slowly injected into the slurry at a predetermined volume fraction using a micro-injection pump, with the droplet rate controlled at 1 mL / min. Under conditions controlled at 25°C, the mixture is stirred at a low speed of 200 rpm for 30 minutes to uniformly disperse the liquid metal in the slurry into microdroplets with an average particle size of 10 μm.

[0037] Step 4: Place the uniformly mixed slurry obtained in Step 3 into a sealed container for pressure impregnation treatment. First, evacuate to a relative vacuum of 0.08 MPa to remove gas, and then maintain the pressure at 0.2 MPa for 20 minutes to allow the liquid metal to fully impregnate and fill the conductive network pore structure. Then, release the pressure to atmospheric pressure.

[0038] S4. On the upper surface of the carbon fiber substrate, the insulating and thermally conductive layer slurry obtained in S2 and the self-healing conductive layer slurry obtained in S3 are sequentially coated by scraping. The thickness of the insulating and thermally conductive layer after curing is controlled to be 0.02 mm, and the thickness of the self-healing conductive layer after curing is 0.02 mm, forming a preform stacked structure.

[0039] S5. After completing the preform stacking structure, vacuum bag it and control the vacuum level to -0.06MPa. Then, place it in an autoclave for curing. The curing process consists of three stages: In the first stage, the temperature is increased to 90℃ at a heating rate of 2.0℃ / min and held for 30min. During this stage, the vacuum degree is maintained at -0.09MPa and the pressure of the autoclave is 0MPa atmospheric pressure.

[0040] In the second stage, the temperature was increased to 135℃ at a rate of 2.0℃ / min, and then held at that temperature for 2.0h under the condition that the pressure in the autoclave was increased to 0.5MPa.

[0041] In the third stage, the temperature is further increased to 150℃, and the temperature is maintained at 0.5MPa for 60 minutes to complete the final curing.

[0042] After curing, the pressure is maintained and the furnace is allowed to cool naturally to below 50°C at a rate not exceeding 2°C / min. Then, the pressure is released, the vacuum is broken, and the mold is removed and trimmed to obtain a self-healing high lightning strike resistant carbon fiber composite laminate.

[0043] Example 2 This embodiment provides a method for preparing a self-healing, highly lightning-resistant carbon fiber composite laminate, specifically including the following steps: S1. Cut the prepreg made of IM600 carbon fiber and JT1312 epoxy resin system, and lay it up according to the preset layup sequence, with the layup direction being [45° / 0° / -45° / 90°]. 4S The total number of layers is 32. During the laying of the top 1-6 layers, after each layer of prepreg is laid, vertically chopped carbon fibers are evenly embedded into the surface of the currently laid top layer of prepreg, so that the vertically chopped carbon fibers are oriented along the thickness direction and partially embedded in the prepreg layer; the vertically chopped carbon fibers have a length of 1.0 mm and a diameter of 7 μm, and the volume fraction of the vertically chopped carbon fibers is controlled to be 3% of the volume of the resin in the interlayer. Then, the next layer of prepreg is laid until the carbon fiber base layer prefabricated structure is formed.

[0044] S2. Preparation of the insulating and thermally conductive layer paste, including the following steps: S2.1 Take epoxy resin and adjust its viscosity to 3000 cps. Add honeycomb hexagonal boron nitride powder with a particle size of 5 μm to the resin at a rate of 30 wt% of the resin mass.

[0045] S2.2 was mechanically stirred at 800 rpm for 20 min and then ultrasonically dispersed at 300 W for 30 min to uniformly disperse hexagonal boron nitride in the resin matrix; then degassed under a vacuum of -0.09 MPa for 15 min to obtain the insulating and thermally conductive layer slurry.

[0046] S3. Preparation of self-healing conductive layer slurry, including the following steps: Step 1: Carbon nanotubes and expanded graphite are dispersed in a resin matrix. The carbon nanotubes have a diameter of 20 nm and a length of 15 μm. The expanded graphite has a thickness of 70 nm and a length of 15 μm. The mass ratio of carbon nanotubes to expanded graphite is 1:3, and the total amount of carbon nanotubes and expanded graphite added is 8 wt% of the resin matrix mass. The mixture is mechanically stirred at 1000 rpm for 30 min and ultrasonically dispersed at 300 W for 20 min to form a uniform composite conductive network slurry.

[0047] Step 2: The carbon nanotubes and expanded graphite in the composite conductive network slurry obtained in Step 1 are surface activated by low-temperature oxygen plasma treatment. The treatment power is 55W and the treatment time is 4min.

[0048] Step 3: After activation treatment, gallium-based liquid metal microdroplets are introduced into the composite conductive network slurry to obtain a uniformly mixed slurry. The gallium-based liquid metal microdroplets are eutectic gallium-indium alloys, in which the mass ratio of gallium to indium is 75.5:24.5, and the volume fraction of the gallium-based liquid metal microdroplets accounts for 15% of the total volume of the self-healing conductive layer.

[0049] The introduction of gallium-based liquid metal microdroplets employs a combination of vacuum-assisted infiltration and mechanical stirring. Specifically, the composite conductive network slurry is placed in a sealable stirring container, and a vacuum is drawn to -0.09 MPa and maintained for 8 minutes to remove air bubbles trapped in the slurry. The negative pressure environment allows the resin matrix to fully wet the filler surface. Subsequently, nitrogen gas is introduced into the stirring container to pressurize it to 0.3 MPa. Under pressurized conditions, liquid metal is slowly injected into the slurry at a predetermined volume fraction using a micro-injection pump, with the droplet rate controlled at 2 mL / min. Under conditions controlled at 25°C, the mixture is stirred at a low speed of 500 rpm for 15 minutes to uniformly disperse the liquid metal in the slurry into microdroplets with an average particle size of 30 μm.

[0050] Step 4: Place the uniformly mixed slurry obtained in Step 3 into a sealed container for pressure impregnation treatment. First, evacuate to a relative vacuum of 0.09 MPa to remove gas, and then maintain the pressure at 0.3 MPa for 15 minutes to allow the liquid metal to fully impregnate and fill the conductive network pore structure. Then, release the pressure to atmospheric pressure.

[0051] S4. On the upper surface of the carbon fiber substrate, the insulating and thermally conductive layer slurry obtained in S2 and the self-healing conductive layer slurry obtained in S3 are sequentially coated by scraping. The thickness of the insulating and thermally conductive layer after curing is controlled to be 0.15 mm, and the thickness of the self-healing conductive layer after curing is 0.15 mm, forming a preform stacked structure.

[0052] S5. After completing the preform stacking structure, vacuum bag it and control the vacuum level to -0.09MPa. Then, place it in an autoclave for curing. The curing process consists of three stages: In the first stage, the temperature is increased to 90℃ at a heating rate of 2.0℃ / min and held for 30min. During this stage, the vacuum degree is maintained at -0.09MPa and the pressure of the autoclave is 0MPa atmospheric pressure.

[0053] In the second stage, the temperature was increased to 135℃ at a rate of 2.0℃ / min, and then held at that temperature for 2.0h under the condition that the pressure in the autoclave was increased to 0.5MPa.

[0054] In the third stage, the temperature is further increased to 150℃, and the temperature is maintained at 0.5MPa for 60 minutes to complete the final curing.

[0055] After curing, the pressure is maintained and the furnace is allowed to cool naturally to below 50°C at a rate not exceeding 3°C / min. Then, the pressure is released, the vacuum is broken, and the mold is removed and trimmed to obtain a self-healing high lightning strike resistant carbon fiber composite laminate.

[0056] Example 3 This embodiment provides a method for preparing a self-healing, highly lightning-resistant carbon fiber composite laminate, specifically including the following steps: S1. Cut the prepreg made of IM600 carbon fiber and JT1312 epoxy resin system, and lay it up according to the preset layup sequence, with the layup direction being [45° / 0° / -45° / 90°]. 4S The total number of layers is 32. During the laying of the top 1-6 layers, after every two layers of prepreg, vertically chopped carbon fibers are evenly embedded into the surface of the currently laid top layer of prepreg, so that the vertically chopped carbon fibers are oriented along the thickness direction and partially embedded in the prepreg layer; the vertically chopped carbon fibers have a length of 2.0 mm and a diameter of 10 μm, and the volume fraction of the vertically chopped carbon fibers is controlled to be 8% of the volume of the resin in the interlayer. Then, the next layer of prepreg is laid until the carbon fiber base layer prefabricated structure is formed.

[0057] S2. Preparation of the insulating and thermally conductive layer paste, including the following steps: S2.1 Take epoxy resin and adjust its viscosity to 5000 cps. Add honeycomb hexagonal boron nitride powder with a particle size of 10 μm to the resin at a rate of 50 wt% of the resin mass.

[0058] S2.2 was mechanically stirred at 1500 rpm for 15 min and then ultrasonically dispersed at 500 W for 10 min to uniformly disperse hexagonal boron nitride in the resin matrix; then degassed under a vacuum of -0.08 MPa for 10 min to obtain the insulating and thermally conductive layer slurry.

[0059] S3. Preparation of self-healing conductive layer slurry, including the following steps: Step 1: Carbon nanotubes and expanded graphite are dispersed in a resin matrix. The carbon nanotubes have a diameter of 20 nm and a length of 15 μm. The expanded graphite has a thickness of 70 nm and a length of 15 μm. The mass ratio of carbon nanotubes to expanded graphite is 1:5, and the total amount of carbon nanotubes and expanded graphite added is 20 wt% of the resin matrix. The mixture is mechanically stirred at 2000 rpm and ultrasonically dispersed at 500 W for 10 min to form a uniform composite conductive network slurry.

[0060] Step 2: The carbon nanotubes and expanded graphite in the composite conductive network slurry obtained in Step 1 are surface activated by low-temperature oxygen plasma treatment. The treatment power is 55W and the treatment time is 4min.

[0061] Step 3: After activation treatment, gallium-based liquid metal microdroplets are introduced into the composite conductive network slurry to obtain a uniformly mixed slurry. The gallium-based liquid metal microdroplets are eutectic gallium-indium alloys, in which the mass ratio of gallium to indium is 75.5:24.5, and the volume fraction of the gallium-based liquid metal microdroplets accounts for 35% of the total volume of the self-healing conductive layer.

[0062] The introduction of gallium-based liquid metal microdroplets employs a combination of vacuum-assisted infiltration and mechanical stirring. Specifically, the composite conductive network slurry is placed in a sealable stirring container, and a vacuum is drawn to -0.10 MPa and maintained for 5 minutes to remove air bubbles trapped in the slurry. The negative pressure environment allows the resin matrix to fully wet the filler surface. Subsequently, nitrogen gas is introduced into the stirring container to pressurize it to 0.5 MPa. Under pressurized conditions, liquid metal is slowly injected into the slurry at a predetermined volume fraction using a micro-injection pump, with the droplet rate controlled at 3 mL / min. Under conditions where the temperature is controlled at 30°C, low-speed stirring is performed at 800 rpm for 5 minutes to uniformly disperse the liquid metal in the slurry into microdroplets with an average particle size of 100 μm.

[0063] Step 4: Place the uniformly mixed slurry obtained in Step 3 into a sealed container for pressure impregnation treatment. First, evacuate to a relative vacuum of 0.10 MPa to remove gas, then maintain pressure at 0.5 MPa for 5 minutes to allow the liquid metal to fully impregnate and fill the conductive network pore structure, and then release the pressure to normal pressure.

[0064] S4. On the upper surface of the carbon fiber substrate, the insulating and thermally conductive layer slurry obtained in S2 and the self-healing conductive layer slurry obtained in S3 are sequentially coated by scraping. The thickness of the insulating and thermally conductive layer after curing is controlled to be 0.30 mm, and the thickness of the self-healing conductive layer after curing is 0.30 mm, forming a preform stacked structure.

[0065] S5. After completing the preform stacking structure, vacuum bag the preforms, controlling the vacuum level to -0.10 MPa, and then place them in an autoclave for curing. The curing process consists of three stages: In the first stage, the temperature is increased to 90℃ at a heating rate of 2.0℃ / min and held for 30min. During this stage, the vacuum degree is maintained at -0.09MPa and the pressure of the autoclave is 0MPa atmospheric pressure.

[0066] In the second stage, the temperature was increased to 135℃ at a rate of 2.0℃ / min, and then held at that temperature for 2.0h under the condition that the pressure in the autoclave was increased to 0.5MPa.

[0067] In the third stage, the temperature is further increased to 150℃, and the temperature is maintained at 0.5MPa for 60 minutes to complete the final curing.

[0068] After curing, the pressure is maintained and the furnace is allowed to cool naturally to below 50°C at a rate not exceeding 3°C / min. Then, the pressure is released, the vacuum is broken, and the mold is removed and trimmed to obtain a self-healing high lightning strike resistant carbon fiber composite laminate.

[0069] Example 4 This embodiment provides a method for preparing a self-healing, highly lightning-resistant carbon fiber composite laminate, specifically including the following steps: S1. Cut the prepreg made of IM600 carbon fiber and JT1312 epoxy resin system, and lay it up according to the preset layup sequence, with the layup direction being [45° / 0° / -45° / 90°]. 4S The prepreg is laid in a cyclic symmetrical configuration, with a total of 32 layers. During the laying of the top 1-6 layers, after each layer of prepreg is laid, vertically chopped carbon fibers are evenly embedded into the surface of the currently laid top layer of prepreg, ensuring that the vertically chopped carbon fibers are oriented along the thickness direction and partially embedded in the prepreg layer. The vertically chopped carbon fibers have a length of 0.5 mm and a diameter of 7 μm, and their volume fraction is controlled to be 3% of the volume of the resin in the interlayer. The laying environment temperature is controlled at 28℃, and the relative humidity is controlled at 50%. The next layer of prepreg is then laid until the carbon fiber substrate prefabricated structure is formed.

[0070] S2. Preparation of the insulating and thermally conductive layer paste, including the following steps: S2.1 Take epoxy resin and adjust its viscosity to 3000 cps. Weigh hexagonal boron nitride powder and pre-treat it with a silane coupling agent: disperse the hexagonal boron nitride powder in anhydrous ethanol, add 2 wt% of silane coupling agent KH560 (based on the filler mass), stir and react at 65℃ for 3 h, filter, wash, and vacuum dry. Add the modified honeycomb hexagonal boron nitride powder with a particle size of 5 μm to the resin at a rate of 30 wt% of the resin mass.

[0071] S2.2 was mechanically stirred at 800 rpm for 20 min and ultrasonically dispersed at 200 W for 10 min to uniformly disperse hexagonal boron nitride in the resin matrix; then degassed under a vacuum of -0.08 MPa for 15 min to obtain the insulating and thermally conductive layer slurry.

[0072] S3. Preparation of self-healing conductive layer slurry, including the following steps: Step 1: Carbon nanotubes and expanded graphite are dispersed in a resin matrix. The carbon nanotubes have a diameter of 20 nm and a length of 15 μm; the expanded graphite has a thickness of 70 nm and a length of 15 μm; the mass ratio of carbon nanotubes to expanded graphite is 1:3, and the total amount of carbon nanotubes and expanded graphite added is 8 wt% of the resin matrix mass. JT1312 compatible epoxy resin is preheated to 45°C, and carbon nanotubes and expanded graphite powder are added. The mixture is mechanically stirred at 1000 rpm for 30 min, and then ultrasonically dispersed at 300 W for 20 min. During ultrasonic dispersion, a pulse mode of 5 s ultrasonic waves followed by 3 s intermittent waves is used, combined with circulating water cooling, to form a uniform composite conductive network slurry.

[0073] Step 2: The carbon nanotubes and expanded graphite in the composite conductive network slurry obtained in Step 1 are surface activated by low-temperature oxygen plasma treatment. The treatment power is 55W and the treatment time is 4min.

[0074] Step 3: After activation treatment, gallium-based liquid metal microdroplets are introduced into the composite conductive network slurry to obtain a uniformly mixed slurry. The gallium-based liquid metal microdroplets are eutectic gallium-indium alloys, in which the mass ratio of gallium to indium is 75.5:24.5, and the volume fraction of the gallium-based liquid metal microdroplets accounts for 15% of the total volume of the self-healing conductive layer.

[0075] The introduction of gallium-based liquid metal microdroplets employs a combination of vacuum-assisted infiltration and mechanical stirring. Specifically, the composite conductive network slurry is placed in a sealable stirring container, and a vacuum is drawn to -0.09 MPa and maintained for 10 minutes to remove air bubbles trapped in the slurry. The negative pressure environment allows the resin matrix to fully wet the filler surface. Subsequently, nitrogen gas is introduced into the stirring container to pressurize it to 0.3 MPa. Under pressurized conditions, liquid metal is slowly injected into the slurry at a predetermined volume fraction using a micro-injection pump, with the droplet rate controlled at 2 mL / min. Under conditions controlled at 25°C, the mixture is stirred at a low speed of 500 rpm for 10 minutes to uniformly disperse the liquid metal in the slurry into microdroplets with an average particle size of 25 μm.

[0076] Step 4: Place the uniformly mixed slurry obtained in Step 3 into a sealed container for pressure impregnation treatment. First, evacuate to a relative vacuum of 0.09 MPa to remove gas, and then maintain the pressure at 0.3 MPa for 15 minutes to allow the liquid metal to fully impregnate and fill the conductive network pore structure. Then, release the pressure to atmospheric pressure.

[0077] S4. On the upper surface of the carbon fiber substrate, the insulating and thermally conductive layer slurry obtained in S2 and the self-healing conductive layer slurry obtained in S3 are sequentially coated using a scraping method. The scraping direction is uniformly advanced in a single direction, inducing the hexagonal boron nitride sheets to align in the in-plane direction. The thickness of the insulating and thermally conductive layer after curing is controlled to be 0.08 mm, and the thickness of the self-healing conductive layer after curing is controlled to be 0.10 mm. After the scraping is completed, the layup structure is left to stand at room temperature for 20 minutes to allow its surface to reach a touch-dry state, forming a preformed stacked structure.

[0078] S5. After completing the preform stacking structure, vacuum bag it and control the vacuum level to -0.09MPa. Then, place it in an autoclave for curing. The curing process consists of three stages: In the first stage, the temperature is increased to 90℃ at a heating rate of 2.0℃ / min and held for 30min. During this stage, the vacuum degree is maintained at -0.09MPa and the pressure of the autoclave is 0MPa atmospheric pressure.

[0079] In the second stage, the temperature was increased to 135℃ at a rate of 2.0℃ / min, and then held at that temperature for 2.0h under the condition that the pressure in the autoclave was increased to 0.5MPa.

[0080] In the third stage, the temperature is further increased to 150℃, and the temperature is maintained at 0.5MPa for 60 minutes to complete the final curing.

[0081] After curing, the pressure is maintained and the furnace is allowed to cool naturally to below 55°C at a rate of 2°C / min. Then, the pressure is released, the vacuum is broken, and the mold is removed and the edges are trimmed to obtain a self-healing high lightning strike resistant carbon fiber composite laminate.

[0082] Example 5 This embodiment provides a method for preparing a self-healing, highly lightning-resistant carbon fiber composite laminate, specifically including the following steps: S1. Cut the prepreg made of IM600 carbon fiber and JT1312 epoxy resin system, and lay it up according to the preset layup sequence, with the layup direction being [45° / 0° / -45° / 90°]. 4SThe total number of layers is 32. During the laying of the top 1-6 layers, after each layer of prepreg is laid, vertically chopped carbon fibers are evenly embedded into the surface of the currently laid top layer of prepreg, so that the vertically chopped carbon fibers are oriented along the thickness direction and partially embedded in the prepreg layer. The vertically chopped carbon fibers have a length of 0.5 mm and a diameter of 7 μm, and the volume fraction of the vertically chopped carbon fibers is controlled to be 3% of the volume of the resin in the interlayer. The laying environment temperature is controlled at 28℃ and the relative humidity is controlled at 50%. Then, the next layer of prepreg is laid until the carbon fiber base layer prefabricated structure is formed.

[0083] S2. Preparation of the insulating and thermally conductive layer paste, including the following steps: S2.1 Take epoxy resin and adjust its viscosity to 3000 cps. Weigh hexagonal boron nitride powder and pre-treat it with a silane coupling agent: disperse the hexagonal boron nitride powder in anhydrous ethanol, add 2 wt% of silane coupling agent KH560 (based on the filler mass), stir and react at 65℃ for 3 h, filter, wash, and vacuum dry. Add the modified honeycomb hexagonal boron nitride powder with a particle size of 5 μm to the resin at a rate of 40 wt% of the resin mass.

[0084] S2.2 was mechanically stirred at 800 rpm for 20 min and ultrasonically dispersed at 200 W for 10 min to uniformly disperse hexagonal boron nitride in the resin matrix; then degassed under a vacuum of -0.08 MPa for 15 min to obtain the insulating and thermally conductive layer slurry.

[0085] S3. Preparation of self-healing conductive layer slurry, including the following steps: Step 1: Carbon nanotubes and expanded graphite are dispersed in a resin matrix. The carbon nanotubes have a diameter of 20 nm and a length of 15 μm; the expanded graphite has a thickness of 70 nm and a length of 15 μm; the mass ratio of carbon nanotubes to expanded graphite is 1:2, and the total amount of carbon nanotubes and expanded graphite added is 12 wt% of the resin matrix mass. JT1312 compatible epoxy resin is preheated to 45°C, and carbon nanotubes and expanded graphite powder are added. The mixture is mechanically stirred at 1000 rpm for 30 min, and then ultrasonically dispersed at 300 W for 20 min. During ultrasonic dispersion, a pulse mode of 5 s ultrasonic waves followed by 3 s intermittent waves is used, combined with circulating water cooling, to form a uniform composite conductive network slurry.

[0086] Step 2: The carbon nanotubes and expanded graphite in the composite conductive network slurry obtained in Step 1 are surface activated by low-temperature oxygen plasma treatment. The treatment power is 55W and the treatment time is 4min.

[0087] Step 3: After activation treatment, gallium-based liquid metal microdroplets are introduced into the composite conductive network slurry to obtain a uniformly mixed slurry. The gallium-based liquid metal microdroplets are eutectic gallium-indium alloys, in which the mass ratio of gallium to indium is 75.5:24.5, and the volume fraction of the gallium-based liquid metal microdroplets accounts for 20% of the total volume of the self-healing conductive layer.

[0088] The introduction of gallium-based liquid metal microdroplets employs a combination of vacuum-assisted infiltration and mechanical stirring. Specifically, the composite conductive network slurry is placed in a sealable stirring container, and a vacuum is drawn to -0.09 MPa and maintained for 10 minutes to remove air bubbles trapped in the slurry. The negative pressure environment allows the resin matrix to fully wet the filler surface. Subsequently, nitrogen gas is introduced into the stirring container to pressurize it to 0.3 MPa. Under pressurized conditions, liquid metal is slowly injected into the slurry at a predetermined volume fraction using a micro-injection pump, with the droplet rate controlled at 2 mL / min. Under conditions controlled at 25°C, the mixture is stirred at a low speed of 500 rpm for 10 minutes to uniformly disperse the liquid metal in the slurry into microdroplets with an average particle size of 25 μm.

[0089] Step 4: Place the uniformly mixed slurry obtained in Step 3 into a sealed container for pressure impregnation treatment. First, evacuate to a relative vacuum of 0.09 MPa to remove gas, and then maintain the pressure at 0.3 MPa for 15 minutes to allow the liquid metal to fully impregnate and fill the conductive network pore structure. Then, release the pressure to atmospheric pressure.

[0090] S4. On the upper surface of the carbon fiber substrate, the insulating and thermally conductive layer slurry obtained in S2 and the self-healing conductive layer slurry obtained in S3 are sequentially coated using a scraping method. The scraping direction is uniformly advanced in a single direction to induce the hexagonal boron nitride sheets to align in the in-plane direction. The thickness of the insulating and thermally conductive layer after curing is controlled to be 0.08 mm, and the thickness of the self-healing conductive layer after curing is controlled to be 0.10 mm. After the scraping is completed, the layup structure is left to stand at room temperature for 30 minutes to allow its surface to reach a touch-dry state, forming a preformed stacked structure.

[0091] S5. After completing the preform stacking structure, vacuum bag it and control the vacuum level to -0.09MPa. Then, place it in an autoclave for curing. The curing process consists of three stages: In the first stage, the temperature is increased to 90℃ at a heating rate of 2.0℃ / min and held for 30min. During this stage, the vacuum degree is maintained at -0.09MPa and the pressure of the autoclave is 0MPa atmospheric pressure.

[0092] In the second stage, the temperature was increased to 135℃ at a rate of 2.0℃ / min, and then held at that temperature for 2.0h under the condition that the pressure in the autoclave was increased to 0.5MPa.

[0093] In the third stage, the temperature was further increased to 150℃ and held at 0.5MPa for 60 minutes to complete the final curing. After curing, the pressure was maintained and the furnace was allowed to cool naturally to below 55℃ at a cooling rate of 2℃ / min. Then, the pressure was released, the vacuum was broken, and the furnace was demolded and trimmed to obtain a self-healing high lightning strike resistant carbon fiber composite laminate.

[0094] Example 6 This embodiment provides a method for preparing a self-healing, highly lightning-resistant carbon fiber composite laminate, specifically including the following steps: S1. Cut the prepreg made of IM600 carbon fiber and JT1312 epoxy resin system, and lay it up according to the preset layup sequence, with the layup direction being [45° / 0° / -45° / 90°]. 4S The total number of layers is 32. During the laying of the top 1-6 layers, after each layer of prepreg is laid, vertically chopped carbon fibers are evenly embedded into the surface of the currently laid top layer of prepreg, so that the vertically chopped carbon fibers are oriented along the thickness direction and partially embedded in the prepreg layer. The vertically chopped carbon fibers have a length of 0.5 mm and a diameter of 7 μm, and the volume fraction of the vertically chopped carbon fibers is controlled to be 3% of the volume of the resin in the interlayer. The laying environment temperature is controlled at 28℃ and the relative humidity is controlled at 50%. Then, the next layer of prepreg is laid until the carbon fiber base layer prefabricated structure is formed.

[0095] S2. Preparation of the insulating and thermally conductive layer paste, including the following steps: S2.1 Take epoxy resin and adjust its viscosity to 3000 cps. Weigh hexagonal boron nitride powder and pre-treat it with a silane coupling agent: disperse the hexagonal boron nitride powder in anhydrous ethanol, add 2 wt% of silane coupling agent KH560 (based on the filler mass), stir and react at 65℃ for 3 h, filter, wash, and vacuum dry. Add the modified honeycomb hexagonal boron nitride powder with a particle size of 5 μm to the resin at a rate of 30 wt% of the resin mass.

[0096] S2.2 was mechanically stirred at 800 rpm for 20 min and ultrasonically dispersed at 200 W for 10 min to uniformly disperse hexagonal boron nitride in the resin matrix; then degassed under a vacuum of -0.08 MPa for 15 min to obtain the insulating and thermally conductive layer slurry.

[0097] S3. Preparation of self-healing conductive layer slurry, including the following steps: Step 1: Carbon nanotubes and expanded graphite are dispersed in a resin matrix. The carbon nanotubes have a diameter of 20 nm and a length of 15 μm; the expanded graphite has a thickness of 70 nm and a length of 15 μm; the mass ratio of carbon nanotubes to expanded graphite is 1:3, and the total amount of carbon nanotubes and expanded graphite added is 8 wt% of the resin matrix mass. JT1312 compatible epoxy resin is preheated to 45°C, and carbon nanotubes and expanded graphite powder are added. The mixture is mechanically stirred at 1000 rpm for 30 min, and then ultrasonically dispersed at 300 W for 20 min. During ultrasonic dispersion, a pulse mode of 5 s ultrasonic waves followed by 3 s intermittent waves is used, combined with circulating water cooling, to form a uniform composite conductive network slurry.

[0098] Step 2: The carbon nanotubes and expanded graphite in the composite conductive network slurry obtained in Step 1 are surface activated by low-temperature oxygen plasma treatment. The treatment power is 55W and the treatment time is 4min.

[0099] Step 3: After activation treatment, gallium-based liquid metal microdroplets are introduced into the composite conductive network slurry to obtain a uniformly mixed slurry. The gallium-based liquid metal microdroplets are eutectic gallium-indium alloys, in which the mass ratio of gallium to indium is 75.5:24.5, and the volume fraction of the gallium-based liquid metal microdroplets accounts for 15% of the total volume of the self-healing conductive layer.

[0100] The introduction of gallium-based liquid metal microdroplets employs a combination of vacuum-assisted infiltration and mechanical stirring. Specifically, the composite conductive network slurry is placed in a sealable stirring container, and a vacuum is drawn to -0.09 MPa and maintained for 10 minutes to remove air bubbles trapped in the slurry. The negative pressure environment allows the resin matrix to fully wet the filler surface. Subsequently, nitrogen gas is introduced into the stirring container to pressurize it to 0.3 MPa. Under pressurized conditions, liquid metal is slowly injected into the slurry at a predetermined volume fraction using a micro-injection pump, with the droplet rate controlled at 2 mL / min. Under conditions controlled at 25°C, the mixture is stirred at a low speed of 500 rpm for 10 minutes to uniformly disperse the liquid metal in the slurry into microdroplets with an average particle size of 25 μm.

[0101] Step 4: Place the uniformly mixed slurry obtained in Step 3 into a sealed container for pressure impregnation treatment. First, evacuate to a relative vacuum of 0.09 MPa to remove gas, and then maintain the pressure at 0.3 MPa for 15 minutes to allow the liquid metal to fully impregnate and fill the conductive network pore structure. Then, release the pressure to atmospheric pressure.

[0102] S4. On the upper surface of the carbon fiber substrate, the insulating and thermally conductive layer slurry obtained in S2 and the self-healing conductive layer slurry obtained in S3 are sequentially coated using a scraping method. The scraping direction is uniformly advanced in a single direction, inducing the hexagonal boron nitride sheets to align in the in-plane direction. The thickness of the insulating and thermally conductive layer after curing is controlled to be 0.12 mm, and the thickness of the self-healing conductive layer after curing is controlled to be 0.15 mm. After the scraping is completed, the layup structure is left to stand at room temperature for 25 minutes to allow its surface to reach a touch-dry state, forming a preformed stacked structure.

[0103] S5. After completing the preform stacking structure, vacuum bag it and control the vacuum level to -0.09MPa. Then, place it in an autoclave for curing. The curing process consists of three stages: In the first stage, the temperature is increased to 90℃ at a heating rate of 2.0℃ / min and held for 30min. During this stage, the vacuum degree is maintained at -0.09MPa and the pressure of the autoclave is 0MPa atmospheric pressure.

[0104] In the second stage, the temperature was increased to 135℃ at a rate of 2.0℃ / min, and then held at that temperature for 2.0h under the condition that the pressure in the autoclave was increased to 0.5MPa.

[0105] In the third stage, the temperature was further increased to 150℃ and held at 0.5MPa for 60 minutes to complete the final curing. After curing, the pressure was maintained and the furnace was allowed to cool naturally to below 55℃ at a cooling rate of 2℃ / min. Then, the pressure was released, the vacuum was broken, and the furnace was demolded and trimmed to obtain a self-healing high lightning strike resistant carbon fiber composite laminate.

Claims

1. A self-healing, highly lightning-resistant carbon fiber composite material, characterized in that, It includes a self-healing conductive layer, an insulating and thermally conductive layer, and a carbon fiber substrate layer, which are laid from top to bottom; The self-healing conductive layer comprises a resin matrix and a composite conductive network dispersed in the resin matrix. The composite conductive network is composed of carbon nanotubes densely filled with gallium-based liquid metal droplets and expanded graphite. The insulating and thermally conductive layer is made of honeycomb hexagonal boron nitride and resin uniformly mixed. The carbon fiber substrate layer is made of 32 layers of carbon fiber and epoxy resin prepreg. The first 6 layers of the carbon fiber substrate layer are uniformly laid with vertically chopped carbon fibers, which extend upwards and penetrate through the insulating and thermally conductive layer.

2. The self-repairing high lightning strike resistant carbon fiber composite material according to claim 1, wherein, The thickness of the self-healing conductive layer is 0.02mm-0.30mm, and the thickness of the insulating and thermally conductive layer is 0.02mm-0.30mm.

3. The self-repairing high lightning strike resistant carbon fiber composite material of claim 1, wherein The self-healing conductive layer has a carbon nanotube to expanded graphite mass ratio of 1:(1-5), and the total amount of carbon nanotubes and expanded graphite added is 3wt%-20wt% of the resin matrix mass; the gallium-based liquid metal droplets are eutectic gallium-indium alloys, and the volume fraction of the eutectic gallium-indium alloy accounts for 5%-35% of the total volume of the self-healing conductive layer, with an average particle size of 1μm-100μm; the honeycomb hexagonal boron nitride in the insulating and thermally conductive layer has a particle size of 1μm-10μm, and the amount of hexagonal boron nitride added is 10wt%-50wt% of the resin mass in the insulating and thermally conductive layer.

4. The self-repairing high lightning strike resistant carbon fiber composite material of claim 1, wherein, The vertically chopped carbon fibers have a length of 0.2mm-2mm and a diameter of 5μm-10μm.

5. A method for preparing a self-repairing high lightning strike resistant carbon fiber composite laminate panel, characterized by, Using the composite material according to any one of claims 1-4 includes the following steps: S1. Cut the prepreg and lay it out, and insert vertically chopped carbon fibers into the top 1-6 layers to form a carbon fiber base layer prefabricated structure; S2. Prepare the insulating and thermally conductive layer paste; S3. Prepare a self-healing conductive layer slurry; S4. On the upper surface of the carbon fiber substrate, the insulating and thermally conductive layer slurry and the self-healing conductive layer slurry are coated sequentially by scraping to form a preform stacked structure. S5. Vacuum bag encapsulation of the preform stack structure and curing molding. After curing, demolding and trimming are performed to obtain self-healing high lightning strike resistant carbon fiber composite material.

6. The method for preparing the self-healing high lightning strike resistant carbon fiber composite laminate according to claim 5, characterized in that, The specific steps of S1 are as follows: cut the prepreg made of carbon fiber and epoxy resin, lay it up in the preset layering sequence, and during the laying of the top 1-6 layers, after laying one or two layers of prepreg, uniformly insert vertically chopped carbon fibers into the surface of the currently laid top layer of prepreg, so that the vertically chopped carbon fibers are oriented along the thickness direction and partially embedded in the layer of prepreg. Control the volume fraction of the vertically chopped carbon fibers to be 0.5%-8% of the volume of the resin in the interlayer. Then continue to lay the next layer of prepreg until the carbon fiber base layer prefabricated structure is formed.

7. The method for preparing the self-healing high lightning strike resistant carbon fiber composite laminate according to claim 5, characterized in that, The preparation of the insulating and thermally conductive layer paste described in S2 includes the following steps: S2.1, Take epoxy resin and adjust its viscosity to be within the range of 1000cps-5000cps; add hexagonal boron nitride powder with a particle size of 1μm-10μm to the resin, the amount of which is 10wt%-50wt% of the resin mass; S2.2, honeycomb hexagonal boron nitride powder with a particle size of 1μm-10μm is added to the resin matrix, wherein the amount of hexagonal boron nitride powder added is 10wt%-50wt% of the resin matrix mass; mechanical stirring is performed at a speed of 300rpm-1500rpm for 15min-30min, and ultrasonic dispersion is performed at a power of 100W-500W for 10min-40min to uniformly disperse the hexagonal boron nitride in the resin matrix; then degassing is performed under vacuum conditions of -0.06MPa to -0.10MPa for 10min-30min to obtain the insulating and thermally conductive layer slurry.

8. The method for preparing the self-healing high lightning strike resistant carbon fiber composite laminate according to claim 5, characterized in that, S3 specifically includes the following steps: Step 1: Disperse carbon nanotubes and expanded graphite in a resin matrix, mechanically stir at 500 rpm-2000 rpm, and ultrasonically disperse at 100 W-500 W for 10 min-60 min to form a uniform composite conductive network slurry. Step 2: The carbon nanotubes and expanded graphite in the composite conductive network slurry obtained in Step 1 are surface activated by plasma treatment. Step 3: After activation treatment, gallium-based liquid metal microdroplets are introduced into the composite conductive network slurry to obtain a uniformly mixed slurry; Step 4: Place the uniformly mixed slurry obtained in Step 3 into a sealed container for pressure impregnation treatment. First, evacuate to a relative vacuum of 0.08MPa-0.1MPa to remove gas. Then, maintain the pressure at 0.2MPa-0.5MPa for 5min-20min to allow the liquid metal to fully impregnate and fill the conductive network pore structure. Then, release the pressure to atmospheric pressure.

9. The method for preparing the self-healing high lightning strike resistant carbon fiber composite laminate according to claim 8, characterized in that, Step 3 introduces gallium-based liquid metal microdroplets using a combination of vacuum-assisted infiltration and mechanical stirring. The specific steps are as follows: The composite conductive network slurry is placed in a sealable stirring container, and a vacuum is drawn to -0.08 MPa to -0.10 MPa, maintained for 5-10 minutes to remove air bubbles trapped in the slurry. The negative pressure environment allows the resin matrix to fully wet the filler surface. Nitrogen gas is then introduced into the stirring container and pressurized to 0.2 MPa to 0.5 MPa. Under this pressure, liquid metal is slowly injected into the slurry at a predetermined volume fraction using a micro-injection pump, with the droplet rate controlled at 1 mL / min to 3 mL / min. At a temperature controlled at 25℃ to 30℃, low-speed stirring is performed at 200 rpm to 800 rpm for 5-30 minutes, ensuring the liquid metal is uniformly dispersed in the slurry as microdroplets with an average particle size of 1 μm to 100 μm.

10. The method for preparing the self-healing high lightning strike resistant carbon fiber composite laminate according to claim 5, characterized in that, The specific steps of S5 are as follows: after completing the preform stacking structure, vacuum bag sealing is performed, and the vacuum degree is controlled to -0.06MPa to -0.10MPa, followed by curing and molding; the curing and molding is divided into three stages; The first stage involves heating to 80℃-100℃ at a rate of 1℃ / min-5℃ / min and holding at that temperature for 20min-60min. During this stage, the vacuum level is maintained at -0.09MPa and the pressure in the autoclave is 0MPa at atmospheric pressure. In the second stage, the temperature is increased to 120℃-160℃ at a heating rate of 2.0℃ / min, and then held at that temperature for 2 hours under the condition that the pressure in the autoclave is increased to 0.5-0.7MPa. In the third stage, the temperature is further increased to 120℃-180℃, and the temperature is maintained at 0.5MPa for 50-80 minutes to complete the final curing. After curing, the pressure is maintained and the furnace is allowed to cool naturally to below 55°C at a rate not exceeding 3°C / min. Then, the pressure is released, the vacuum is broken, and the mold is removed and trimmed to obtain a self-healing high lightning strike resistant carbon fiber composite material.

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