Phase change microcapsule and preparation method for epoxy resin self-healing composite insulating material doped with phase change microcapsule

Abstract

A phase change microcapsule and a preparation method for an epoxy resin self-healing composite insulating material doped with the phase change microcapsule. The phase change microcapsule has a core-shell structure, with 500 nm silicon carbide particles and octacosane as a core, and an outer layer is coated with Fe3O4@SiO2 nanoparticles.

Description

A method for preparing a phase change microcapsule and an epoxy resin self-healing composite insulation material doped with phase change microcapsules Technical Field

[0001] This invention belongs to the field of materials science, specifically relating to a method for preparing a phase change microcapsule and an epoxy resin self-healing composite insulating material doped with phase change microcapsules. Background Technology

[0002] Polymer-based composite materials are made by combining high-molecular materials with reinforcing materials possessing high strength, high modulus, and temperature resistance. These composites typically exhibit high specific strength and modulus, good chemical corrosion resistance, and excellent machinability, thus finding wide application in aerospace, automotive, and sporting goods industries. Epoxy resin, due to its excellent adhesion and low curing shrinkage, is generally considered a high-performance composite matrix. However, in insulating applications, the difficulty in timely detection or repair of micro-damage within epoxy resin-based materials severely hinders their further promotion and application in high-voltage fields.

[0003] In practical applications, epoxy resin-based composite insulation materials inevitably suffer microscopic crack damage due to defects in manufacturing processes, transportation conditions, installation methods, and the complex working environment of strong magnetic fields and electricity. However, there is currently a lack of effective solutions to the problem of microscopic damage degradation within epoxy resin-based composite insulation materials. Most research on effectively preventing microscopic crack damage within epoxy resin-based composite insulation materials focuses on using nano-doping to improve the electrical breakdown performance and increase the dielectric constant of the insulation material, while research on how to efficiently and autonomously repair internal damage is lacking.

[0004] The curing mechanism of microcapsules in epoxy resin-based composite insulation materials typically involves encapsulating a liquid repair agent within the microcapsule wall. When damage breaks the capsule wall, the repair agent flows out to fill the damaged channel and cures under external conditions such as temperature and light, thus repairing the insulation material. However, because the cured components of existing repair agents are not entirely identical to the epoxy resin matrix, intrinsic defects appear at the repair interface of the epoxy resin-based composite insulation material. This leads to a decrease in the mechanical properties of the epoxy resin-based composite insulation material, limiting the widespread application of microcapsule self-healing technology in the fields of high voltage and insulation technology.

[0005] Existing microcapsule self-healing technology has made significant progress in the field of self-healing epoxy resin-based composite insulation materials. However, the microcapsule repair agent in epoxy resin-based composite insulation materials requires external stimulation or induced curing through chemical reactions. This curing process is irreversible and can only perform a single repair. To solve the problem of irreversible curing and single-repair capability of traditional repair agents, it is urgent to improve existing technologies and innovatively develop a reusable, high-performance epoxy resin self-healing composite insulation material with a recycling pathway. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0008] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing phase change microcapsules and epoxy resin self-healing composite insulating materials doped with phase change microcapsules.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a phase change microcapsule, characterized in that: the phase change microcapsule has a core-shell structure, wherein silicon carbide particles and octacosane are used as the core, and Fe3O4@SiO2 nanoparticles are coated on the outer layer.

[0010] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing phase change microcapsules, characterized by comprising:

[0011] Fe3O4 nanoparticles were dissolved in anhydrous ethanol and ultrasonically dispersed to obtain dispersion solution 1; concentrated ammonia was added dropwise to dispersion solution 1 to obtain dispersion solution 2; and ethyl silicate was added dropwise to dispersion solution 2 to obtain dispersion solution 3.

[0012] Dispersion solution 3 was mixed and stirred under heating conditions. After solid-liquid separation, it was filtered and washed with methanol and deionized water respectively, and dried at room temperature to obtain Fe3O4@SiO2 nanoparticles.

[0013] Fe3O4@SiO2 nanoparticles were dissolved in tetradecyltrimethylammonium bromide solution to obtain an aqueous solution; silicon carbide particles were added to octacosanane to obtain an oil solution.

[0014] The oil phase solution and the aqueous phase solution were stirred at room temperature to obtain an oil-water emulsion, which was then filtered and washed with methanol and deionized water, respectively, and dried at room temperature to obtain the phase change microcapsules.

[0015] In a preferred embodiment of the preparation method described in this invention, the mass ratio of the Fe3O4 nanoparticles to anhydrous ethanol is 1.0–1.1:35–40.

[0016] In a preferred embodiment of the preparation method described in this invention, the mass ratio of the dispersion solution 1 to concentrated ammonia is 1.0–1.2:1.5–1.7; and the mass ratio of the ethyl silicate to the dispersion solution 2 is 1.0–1.1:42–45.

[0017] In a preferred embodiment of the preparation method described in this invention, the mass ratio of the aqueous phase solution to the oil phase solution is 18-22:12-15.

[0018] In a preferred embodiment of the preparation method of the present invention, the mass ratio of Fe3O4@SiO2 nanoparticles to tetradecyltrimethylammonium bromide in the aqueous solution is 0.9–1.3:30–38. In another preferred embodiment of the preparation method of the present invention, the mass ratio of silicon carbide particles to octadecane in the oil solution is 1.1–1.4:30–34.

[0019] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a self-healing composite insulating material of epoxy resin doped with phase change microcapsules, characterized in that it comprises:

[0020] A room-temperature curing epoxy resin and curing agent are used as the matrix; phase change microcapsules are mixed with the matrix, and the mixed sample is degassed and cured at room temperature to obtain the doped phase change microcapsule epoxy resin self-healing composite insulation material.

[0021] In a preferred embodiment of the preparation method described in this invention, the mass ratio of the room-temperature curing epoxy resin to the curing agent is 1.0–1.2: 0.65–0.85.

[0022] In a preferred embodiment of the preparation method described in this invention, the total content of the phase change microcapsules is 2-8 wt%.

[0023] Beneficial effects of this invention:

[0024] Regarding thermal conductivity, this invention shows an upward trend in the thermal conductivity of the epoxy resin-based composite insulation material as the microcapsule content increases from 0 wt%. The addition of microcapsules with Fe3O4@SiO2 nanoparticles as the shell enhances the overall thermal conductivity of the material. Furthermore, the microencapsulated repair agent of this invention not only heals cracks but also provides excellent thermal conductivity for the epoxy resin-based composite insulation material. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0026] Figure 1 shows the scanning electron microscope (SEM) characterization of 500 nm silicon carbide particles and octadecane microcapsules with Fe3O4@SiO2 nanoparticles as the outer shell according to the present invention.

[0027] Figure 2 is a bar graph showing the effect of different microcapsule contents on the thermal conductivity of epoxy resin-based composite insulating materials in the embodiments and comparative examples of the present invention.

[0028] Figure 3 shows the effect of the self-healing epoxy resin-based composite insulating material of the phase change microcapsule of the present invention on scratch damage self-healing.

[0029] Figure 4 is a bar graph showing the tensile strength of epoxy resin composites with different microcapsule contents in the embodiments and comparative examples of the present invention.

[0030] Figure 5 is a bar graph showing the effect of different microcapsule contents of repair agents on the self-healing efficiency of epoxy resin composite materials in the embodiments and comparative examples of the present invention. Detailed Implementation

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0032] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0033] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0034] Unless otherwise specified, all raw materials used in the embodiments of this invention are commercially available. See Table 1 for details.

[0035] Table 1

[0036] The performance testing methods for the epoxy resin self-healing composite insulating materials with doped phase change microcapsules prepared in the various embodiments and comparative examples of this invention refer to:

[0037] Tensile Strength Test: This tensile strength test was conducted according to GB / T 1040.2-2003 "Determination of Tensile Properties of Plastics Part 2: Test Conditions for Molded and Extruded Plastics" and GB / T 41929-2022 "Test Methods for Epoxy Resins in Plastics". According to the standard requirements, standard-sized epoxy resin samples were prepared with the following dimensions: length L = 150 mm, width b = 10 mm ± 0.1 mm, thickness d = 4 mm ± 0.1 mm, and gauge length L0 = 50 mm (i.e., the initial distance between the two clamps). An electronic universal testing machine, model WDW-100E (maximum test force 100 kN, accuracy class 1), was selected, equipped with standard tensile clamps and an extensometer (for measuring deformation). The experimental steps are as follows: First, the dimensions of the sample were measured using a vernier caliper or micrometer to ensure they met the standard requirements, and the data were recorded. Next, the sample surface was cleaned with alcohol and cotton swabs to remove dust and impurities, ensuring the surface was clean and undamaged. Finally, check the power supply, sensors, and control system of the testing machine to ensure they are functioning properly, and ensure the load sensor and displacement sensor are calibrated. Install suitable tensile clamps and extensometers, and adjust their positions and gauge lengths. Clamp both ends of the sample in the upper and lower clamps respectively, ensuring the sample is centered and securely held. Check that the force direction of the sample is consistent with the tensile direction of the testing machine. Set the tensile speed to 5 mm / min and the test mode to stress-strain mode in the testing machine's control software. Start the testing machine and begin the tensile test, observing the deformation of the sample and recording the changes in load and displacement. When the sample breaks, the testing machine automatically stops the test, and the maximum load at fracture is recorded. Perform statistical analysis on the test data of multiple samples, calculating the average value and standard deviation.

[0038] Thermal conductivity testing: This thermal conductivity test was conducted according to ASTM E1461 standard test method: determination of thermal diffusivity using the flash method, and with reference to relevant thermal conductivity testing standards. According to the standard requirements, a circular epoxy resin sample was prepared with the following dimensions: diameter D = 12.7 mm, thickness d = 2 mm. A laser thermal conductivity meter, model LFA 447, was selected. This instrument is based on the laser flash method and is suitable for measuring the thermal diffusivity and thermal conductivity of materials. First, a circular epoxy resin sample with a diameter of 12.7 mm and a thickness of 2 mm was prepared, ensuring a smooth sample surface. Next, graphite was sprayed onto the sample surface to increase the sample's light energy absorption ratio and infrared emissivity. The laser thermal conductivity meter was started and the water bath was turned on, maintaining a stable state for at least 30 minutes. The sample tray was placed in the test position, ensuring the sample was tested under a protective atmosphere. The laser thermal conductivity meter was started, with the laser source instantly emitting a light pulse, uniformly irradiating the lower surface of the sample, causing it to absorb light energy and raise its temperature. The temperature rise of the sample's upper surface was continuously measured using an infrared detector, and the temperature rise versus time curve was recorded. The thermal diffusivity (α) was calculated using analysis software, and the thermal conductivity (λ) was calculated by combining the sample's specific heat capacity (Cp) and density (ρ): λ = α × Cp × ρ, where the specific heat capacity can be obtained by differential scanning calorimetry (DSC).

[0039] Self-healing efficiency test: This electrical performance test is based on GB / T 1408.1-2017 Measurement of dielectric properties of plastic and adhesive insulating materials—Part 1: General guidelines and GB / T 1408.2-2017 Measurement of dielectric properties of plastic and adhesive insulating materials—Part 2: Measurement of dielectric loss tangent. According to the standard requirements, a circular epoxy resin sample was prepared with the following dimensions: diameter D = 25 mm, thickness d = 2 mm. A power frequency high-voltage breakdown platform, model ZJC-50E, was selected. This instrument is suitable for testing the breakdown voltage of solid insulating materials, has computer control functions, and the voltage boost rate can be adjusted between 10V / s and 5kV / s. A circular epoxy resin sample with a diameter of 25 mm and a thickness of 2 mm was prepared, ensuring a smooth sample surface. The sample surface was cleaned to remove dust and impurities, ensuring a defect-free surface. The power frequency high-voltage breakdown platform was turned on and preheated to ensure the instrument was in a stable state. Place the sample between the test electrodes, ensuring good contact. The entire electrode system must be immersed in filtered transformer oil to prevent corona discharge from affecting the breakdown voltage. Set the boost rate to 1 kV / s in the instrument control software. Start the test, rotating the booster to gradually increase the voltage until the sample breaks down, and record the voltage value at breakdown. Calculate the breakdown field strength (E) using the formula: E = U / d, where U is the breakdown voltage and d is the sample thickness. Perform statistical analysis on the test data of multiple samples, using the Weibull distribution model to analyze the breakdown data to obtain a more accurate withstand voltage strength. Calculate the self-healing efficiency by comparing the breakdown strength of the samples before and after the self-healing process using the formula η = E1 / E2, where E1 is the epoxy resin breakdown strength after self-healing, and E2 is the original epoxy resin breakdown strength before damage.

[0040] Example 1

[0041] This embodiment provides a method for preparing an epoxy resin self-healing composite insulating material doped with phase change microcapsules:

[0042] (1) Dissolve 1g of Fe3O4 nanoparticles in 50ml of anhydrous ethanol and ultrasonically disperse them for 30min in an ultrasonic dispersion device with a frequency of 40kHz and a power of 200W to prepare dispersion solution 1.

[0043] Add 10 ml of concentrated ammonia solution dropwise to 40 ml of dispersion solution 1 to obtain dispersion solution 2;

[0044] Add 5 ml of ethyl silicate solution dropwise to 30 ml of dispersion solution 2 to obtain dispersion solution 3;

[0045] Dispersion solution 3 was placed in a 50℃ water bath and stirred at a high speed of 1000 rpm for 8 hours. After filtration, it was washed with methanol and deionized water respectively, and dried at room temperature to obtain Fe3O4@SiO2 nanoparticles.

[0046] (2) Add 2g of Fe3O4@SiO2 nanoparticles to 100ml of tetradecyltrimethylammonium bromide with a concentration of 0.06mmol / L, and stir at a high speed of 1200 rpm for 2h at room temperature to obtain an aqueous solution;

[0047] 1g of 500nm silicon carbide particles were mixed with 20g of octadecane and stirred at a high speed of 1000 rpm for 30 min in an oil bath at 120℃ to obtain an oil phase solution.

[0048] (3) The prepared oil phase solution and aqueous phase solution were mixed at a ratio of 1.1:2.6. After the octadecane solidified, the mixture was filtered and washed with methanol and deionized water respectively, and dried at room temperature to obtain microcapsules.

[0049] (4) Mix 90 parts of E51 room temperature curing epoxy resin and 20 parts of 593 curing agent as the matrix; mix the microcapsules prepared in step (3) with the matrix, wherein the content of microcapsules is 2wt%, degas the mixed sample and pour it into a dumbbell-shaped polytetrafluoroethylene mold, and cure at room temperature for 48 hours to obtain a doped phase change microcapsule epoxy resin self-healing composite insulation material.

[0050] Example 2

[0051] The difference from Example 1 is that the content of the two-component microcapsules in step (4) is 4wt%, and the remaining steps are all in accordance with the example, so as to obtain the epoxy resin self-healing composite insulation material doped with phase change microcapsules in this example.

[0052] Example 3

[0053] The difference from Example 1 is that the content of the two-component microcapsules in step (4) is 6wt%, and the remaining steps are all in accordance with the example, so as to obtain the epoxy resin self-healing composite insulation material with doped phase change microcapsules in this example.

[0054] Example 4

[0055] The difference from Example 1 is that the content of the two-component microcapsules in step (4) is 8wt%, and the remaining steps are all in accordance with the example, so as to obtain the epoxy resin self-healing composite insulation material with doped phase change microcapsules in this example.

[0056] Comparative Example 1

[0057] The difference from Example 1 is that only pure epoxy resin samples were prepared. The pure epoxy resin samples were obtained by mixing 90 parts of E51 type room temperature curing epoxy resin and 20 parts of 593 curing agent.

[0058] Comparative Example 2

[0059] The difference from Example 1 is that in step (1), the nanoparticles were ultrasonically dispersed for 30 minutes using an ultrasonic dispersion device with a speed of 500 r / min using a mechanical stirrer instead of using an ultrasonic dispersion device with a speed of 40 kHz and 200 W. The remaining steps were the same as in Example 1. The resulting microcapsules were found to have severe nanoparticle aggregation and failed to be successfully encapsulated.

[0060] Comparative Example 3

[0061] The difference from Example 1 is that in step (2), instead of adding 2g of Fe3O4@SiO2 nanoparticles to 100ml of tetradecyltrimethylammonium bromide with a concentration of 0.06mmol / L, 1g of Fe3O4@SiO2 nanoparticles to 100ml of tetradecyltrimethylammonium bromide with a concentration of 0.06mmol / L was added. The remaining steps and processes were the same as in the Example. The result of this comparative example is that the shell and core material ratio was unbalanced, which prevented the formation of microcapsules.

[0062] Comparative Example 4

[0063] The difference from Example 1 is that in step (2), octadecane is changed to docosane. The remaining steps are the same as in Example 1, and the surface wrinkle morphology phase change microcapsules of this comparative example are obtained.

[0064] Comparative Example 5

[0065] The difference from Example 1 is that in step (2), 1g of 500nm silicon carbide particles are adjusted to 1g of 1um carbon nanotubes. The remaining steps are the same as in Example 1, and the carbon nanotube modified phase change microcapsules of this comparative example are obtained.

[0066] Comparative Example 6

[0067] The difference from Example 1 is that in step (2), 1g of 500nm silicon carbide particles are changed to 1g of 1um boron nitride particles. The remaining steps are the same as in Example 1, so as to obtain the boron nitride particle modified phase change microcapsules of this comparative example.

[0068] Example 5

[0069] The thermal conductivity of the samples prepared in Examples 1-4 and Comparative Example 1 was tested.

[0070] Figure 2 shows the variation of thermal conductivity of the epoxy resin self-healing composite insulation material doped with phase change microcapsules with microcapsule content. The thermal conductivity value is the average of 6 measurements. The thermal conductivity of pure epoxy resin is 0.2063 W / m·K. The results show that as the microcapsule content increases from 0 wt% to 8 wt%, the thermal conductivity of the epoxy resin composite material gradually increases to 0.3481 W / m·K. Compared with pure epoxy resin, the thermal conductivity of the self-healing epoxy resin composite material is increased, which may be due to the addition of microcapsules with Fe3O4@SiO2 nanoparticles as the shell, which cross-link to form a thermally conductive network and improve the thermal conductivity of the composite material. The significance of the improved thermal conductivity can be explained from two aspects. On the one hand, the introduction of phase change microcapsules allows the composite material to maintain good insulation performance while improving thermal conductivity, expanding the application environment of epoxy resin self-healing composite insulation materials. On the other hand, the improved thermal conductivity also enables the epoxy resin self-healing composite insulation material to have a targeted heating function. Octadecane can melt rapidly and flow into the micro-damage channels, and when cooled to room temperature, octadecane solidifies and repairs the damaged channels.

[0071] Example 6

[0072] The self-healing efficiency of the samples prepared in Examples 1-4 and Comparative Example 1 was tested:

[0073] The self-healing efficiency of the sample was evaluated based on the fracture test of the dumbbell-shaped sample.

[0074] This invention utilizes phase change microcapsules containing 500nm silicon carbide particles and octadecane as the core, with Fe3O4@SiO2 nanoparticles coated on the outside to prepare self-healing composite materials. The self-healing efficiency of dumbbell-shaped epoxy resin composites was measured using the same parameters to compare the self-healing efficiency of self-healing epoxy resin composite samples with different microcapsule contents. Figure 4 shows the tensile strength bar graphs of epoxy resin composites with different microcapsule contents in the embodiments and comparative examples of this invention.

[0075] Figure 5 is a bar graph showing the effect of different microcapsule contents of the repair agent on the self-healing efficiency of epoxy resin composites in the embodiments and comparative examples of the present invention. As shown in Figure 5, the self-healing efficiency of the epoxy resin composites significantly increases as the microcapsule content increases from 2 wt% to 8 wt%. When the microcapsule content is 8 wt%, the self-healing efficiency of the epoxy resin composite is 96.87%. Clearly, the self-healing effect is related to the amount of repair agent released by the ruptured microcapsules on the crack surface.

[0076] The relevant properties of the products prepared in each embodiment and comparative example were measured, and the results are shown in Table 2.

[0077] Table 2

[0078] As shown in Figure 1, the microcapsules are relatively uniformly distributed, with most exhibiting spherical or near-spherical shapes and relatively smooth surfaces. The outer surface of the microcapsules is smooth with almost no protrusions, due to the outer shell being Fe3O4@SiO2 nanoparticles. Table 2 shows that Comparative Examples 2 and 3 failed to successfully encapsulate the microcapsules due to severe agglomeration and an imbalance in the shell-core material ratio. The rapid improvement in repair efficiency observed in these examples is attributed to the release of sufficient repair agent from the microcapsules to fill the microcrack spaces. The phase change microcapsules embedded in the composite material system provide sufficient octadecane repair agent for the self-healing of epoxy resin composites and promote the bonding between the new epoxy resin and the original matrix interface.

[0079] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for preparing phase change microcapsules, characterized in that: include, Fe3O4 nanoparticles were dissolved in anhydrous ethanol and ultrasonically dispersed to obtain dispersion solution 1; concentrated ammonia was added dropwise to dispersion solution 1 to obtain dispersion solution 2; and ethyl silicate was added dropwise to dispersion solution 2 to obtain dispersion solution 3. Dispersion solution 3 was mixed and stirred under heating conditions. After solid-liquid separation, it was filtered and washed with methanol and deionized water respectively, and dried at room temperature to obtain Fe3O4@SiO2 nanoparticles. Fe3O4@SiO2 nanoparticles were dissolved in tetradecyltrimethylammonium bromide solution to obtain an aqueous solution; silicon carbide particles were added to octacosanane to obtain an oil solution. The oil phase solution and the aqueous phase solution were stirred at room temperature to obtain an oil-water emulsion, which was then filtered and washed with methanol and deionized water, respectively, and dried at room temperature to obtain the phase change microcapsules.

2. The preparation method according to claim 1, characterized in that: The mass ratio of Fe3O4 nanoparticles to anhydrous ethanol is 1.0–1.1:35–40.

3. The preparation method according to claim 1, characterized in that: The mass ratio of dispersion solution 1 to concentrated ammonia is 1.0-1.2:1.5-1.7; the mass ratio of ethyl silicate to dispersion solution 2 is 1.0-1.1:42-45.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the aqueous phase solution to the oil phase solution is 18-22:12-15.

5. The preparation method according to claim 4, characterized in that: The mass ratio of Fe3O4@SiO2 nanoparticles to tetradecyltrimethylammonium bromide in the aqueous solution is 0.9–1.3:30–38.

6. The preparation method according to claim 4, characterized in that: The mass ratio of silicon carbide particles to octadecane in the oil phase solution is 1.1–1.4:30–34.

7. The phase change microcapsules prepared by the method according to claims 1 to 6, characterized in that: The phase change microcapsules have a core-shell structure, wherein silicon carbide particles and octadecane form the core, and the outer layer is coated with Fe. 3 O 4 @SiO 2 Nanoparticles.

8. A method for preparing an epoxy resin self-healing composite insulating material doped with phase change microcapsules, characterized in that: include, A room-temperature curing epoxy resin and curing agent are used as the matrix; phase change microcapsules are mixed with the matrix, and the mixed sample is degassed and cured at room temperature to obtain the doped phase change microcapsule epoxy resin self-healing composite insulation material.

9. The preparation method according to claim 8, characterized in that: The mass ratio of the room-temperature curing epoxy resin to the curing agent is 1.0-1.2:0.65-0.

85.

10. The preparation method according to claim 8, characterized in that: The total content of the phase change microcapsules is 2-8 wt%.

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