A method for preparing a self-repairable electromagnetic composite material
By forming a crosslinked resin coating on the surface of carbonyl iron powder and compounding it with polyurethane containing a self-healing structure, the problem of electromagnetic wave absorbing materials being easily corroded in complex environments is solved, and excellent self-healing performance and corrosion resistance are achieved.
Patent Information
- Application Number
- CN202310238520.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-13
- Publication Date
- 2025-05-09
- Estimated Expiration
- 2043-03-13
AI Technical Summary
Existing electromagnetic wave absorbing materials are prone to corrosion in wet, salt spray or acidic environments, resulting in a decrease in magnetic properties and loss of electromagnetic properties, making it difficult to meet the needs of long-term chemical stability and electrical and magnetic stability.
Ethoxylated trimethylolpropane triacrylate is used as the crosslinking agent, and the resin crosslinking network is uniformly and densely coated on the surface of carbonyl iron powder through free radical polymerization in solution, and polyurethane containing quadrupole and disulfide bonds is used as the resin matrix to form a self-healing electromagnetic composite material.
It significantly improves the oxidation and electrochemical corrosion resistance of carbonyl iron powder, and achieves self-healing efficiency when damaged, improving the corrosion resistance and adaptability of electromagnetic composite materials.
Smart Images
Figure CN116376268B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of electromagnetic wave absorbing materials and relates to a method for preparing a self-repairable electromagnetic composite material with excellent corrosion resistance and self-repairability. Background Art
[0002] Stealth technology is an important technology in contemporary military warfare and a major trend in the development of future air combat. Absorbing materials are composite materials made by adding electromagnetic wave absorbers as fillers to resin and other matrices. They can absorb and attenuate incident electromagnetic waves and significantly reduce the echo intensity, thereby achieving the purpose of reducing the target radar scattering cross section.
[0003] As an important magnetic metal powder, carbonyl iron powder has high saturation magnetization and low coercive force, and is often used as a functional filler for radar absorbing coatings to make composite materials. However, the carbonyl iron powder used in the coating has small particles, mostly in the micron or nanometer level, with high surface activity, and is very prone to oxidative corrosion, especially when used in humid, salt spray and acidic environments. Serious corrosion problems will occur, and the formation of corrosion products will seriously weaken its electromagnetic properties, which greatly limits the application of carbonyl iron powder. Therefore, most of the research directions of researchers in the industry are to achieve long-term chemical stability and electrical and magnetic stability of the overall electromagnetic absorbing material by surface modification of flaky carbonyl iron powder.
[0004] In current research, coating and modifying carbonyl iron powder by surface treatment technology is an effective method to improve the corrosion resistance of powder. Researchers generally achieve the purpose of powder protection by coating the surface of carbonyl iron powder with a continuous, uniform, dense and non-oxidizable organic or inorganic protective layer to isolate the invasion of external oxygen or other corrosive ions. The existing surface modification methods mainly include: sol-gel, chemical vapor deposition (CVD), atomic deposition (ALD), electrochemical deposition and plasma polymerization.
[0005] However, the existing surface treatment technology has the following problems: the coating layer thickness is often 50-80nm to achieve good corrosion resistance, and a thicker coating layer will significantly reduce the magnetism and cannot meet the actual use requirements; the inorganic coating layer has poor hydrophobicity and poor stability in acidic solutions; the coating layer cannot isolate corrosive media such as water vapor, oxygen, chloride ions and sodium ions, which is not conducive to the corrosion protection of carbonyl iron powder; and the coating layer thickness is uneven, making it difficult to achieve long-term corrosion protection of carbonyl iron powder.
[0006] Therefore, it is urgent to prepare electromagnetic absorbing materials with excellent chemical stability and magnetic stability. Summary of the invention
[0007] In view of the above-mentioned problems or shortcomings, and to solve the problem of relatively insufficient stability of existing electromagnetic absorbing materials, the present invention provides a method for preparing a self-repairable electromagnetic composite material, which improves the stability of electromagnetic absorbing materials from the perspective of self-repair.
[0008] A method for preparing a self-repairable electromagnetic composite material comprises the following steps:
[0009] Step 1: Add 60-70 parts of carbonyl iron powder to 250-300 parts of an acidic solution with a pH of 1-2, mix well, filter, wash with anhydrous ethanol 2-3 times, and then dry the carbonyl iron powder completely at a temperature below 60° C. to clean the oxide on the surface of the carbonyl iron powder and allow the active hydroxyl groups to adhere to the surface of the iron powder.
[0010] Step 2: Mix 50-60 parts of the carbonyl iron powder obtained in step 1, 100-120 parts of anhydrous ethanol and 15-20 parts of methacrylic acid in a reaction container, filter, wash with anhydrous ethanol 2-3 times, and then dry the obtained powder completely at a temperature below 60° C. to introduce double bonds on the surface of the dried carbonyl iron powder, so as to be used for grafting monomers containing a self-healing structure.
[0011] Step 3: Mix 10-20 parts of the carbonyl iron powder obtained in step 2, 4-6 parts of polyvinyl pyrrolidone and 80-100 parts of anhydrous ethanol in a reaction container to obtain a dispersion system A.
[0012] Mix 3-9 parts of ethoxylated trimethylolpropane triacrylate, 3-9 parts of 2-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-one)-ureido)ethyl methacrylate, 3-9 parts of N,N'-(dithiodiylbis(4,1-phenylene))bis(2-methylacrylamide), 0.04-0.12 parts of azobisisobutyronitrile and 10-30 parts of dimethylformamide, by mass, to obtain a mixed solution B.
[0013] Step 4: Under inert protective gas and reflux conditions, the dispersion system A prepared in step 3 is heated to 60-65°C, and the mixed solution B prepared in step 3 is added dropwise at a stirring rate of 400-450rpm. After the addition is completed, the solution polymerization reaction is continued until the cross-linking reaction of the two is complete. The mass ratio of the dispersion system A to the mixed solution B is (3-4):1.
[0014] Step 5: Filter the mixed solution after the reaction in step 4 is completed to obtain a powder, wash the powder with at least 50 parts of dimethylformamide and at least 50 parts of anhydrous ethanol in sequence, and then dry it completely at a temperature not higher than 60° C. to obtain a repairable resin-coated carbonyl iron powder.
[0015] In terms of mass fractions, under inert protective gas and reflux conditions, 4-6 parts of polyethylene glycol 1000, 0.6-1 parts of bis(2-hydroxyethyl) disulfide, 1-3 parts of 1-(6-(3-(1,3-dihydroxy-2-methylpropane-2-yl)urea)hexyl)-3-(6-methyl-4-oxo-1,4-dihydropyridin-2-yl)urea, 2-6 parts of isophorone diisocyanate, 0.02-0.06 parts of dibutyltin dilaurate and 10-30 parts of anhydrous dimethylformamide are reacted at 60-80° C. for 5 hours to obtain a mixed solution C, which is a matrix of a self-healing composite material.
[0016] Step 6: Mix 10-30 parts of the mixed solution C obtained in step 5 and 1-3 parts of the repairable resin-coated carbonyl iron powder, by mass, and dry them completely at a temperature not lower than 80° C. to obtain a self-repairable electromagnetic composite material.
[0017] Furthermore, the acidic solution in step 1 is a 0.01-0.1 mol / L hydrochloric acid solution.
[0018] Furthermore, the inert protective gas in the step is nitrogen.
[0019] Furthermore, the mixing in step 6 is carried out at room temperature in a beaker equipped with a mechanical stirrer at a rate of 100-120 rpm for 2 hours.
[0020] Furthermore, the self-repairable electromagnetic composite material prepared by the above method is used as an electromagnetic wave absorbing material for military targets.
[0021] The present invention uses ethoxylated trimethylolpropane triacrylate as a crosslinking agent, and makes the resin crosslinking network uniformly and densely coated on the surface of carbonyl iron powder through free radical polymerization reaction in solution, and uses polyurethane containing quadruple hydrogen bonds and disulfide bonds as a resin matrix, so as to prepare a self-repairing electromagnetic composite material. The coated carbonyl iron powder has good oxidation resistance, electrochemical corrosion resistance and other properties, and the coating process is simple, and it is easy to adjust the coating layer thickness by controlling the reaction conditions; in addition, after the coated carbonyl iron powder is compounded with the polyurethane matrix, when the composite material is damaged, the self-healing efficiency based on elongation and strength reaches 88% and 85% respectively within two hours, and has excellent self-repairing performance, so that the adaptability of the electromagnetic composite material in complex environments is greatly improved.
[0022] In summary, the present invention uses carbonyl iron powder coated with a cross-linked resin and composites it with a polyurethane containing a self-repairing structure. The electromagnetic composite material finally prepared has excellent self-repairing properties, thereby greatly improving the corrosion resistance of the electromagnetic composite material. The present invention provides a new idea for the long-term easy damage of electromagnetic composite materials in complex environments, resulting in a sharp decline in performance, so that it can be better applied to multiple scenarios, especially for military targets. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 Scanning electron microscope photographs of the coating layers of the carbonyl iron powder prepared in Examples 1-3 with thicknesses from thin to thick.
[0024] Figure 2 This is the X-ray photoelectron spectrum of the carbonyl iron powder prepared in Example 2.
[0025] Figure 3 The electrochemical corrosion Tafel curves of the carbonyl iron powder before coating and the carbonyl iron powder prepared in Examples 1-3 in 3.5% sodium chloride aqueous solution.
[0026] Figure 4 This is an optical microscope photograph of the composite material prepared in Example 2 during the repair process.
[0027] Figure 5 This is the stress-strain curve of the composite material prepared in Example 2 before and after repair.
[0028] Figure 6 3D simulated reflection loss diagram of carbonyl iron powder before coating and carbonyl iron powder prepared in Example 1. DETAILED DESCRIPTION
[0029] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.
[0030] A method for preparing a self-repairable electromagnetic composite material, the parts in the following embodiments are all parts by mass, comprising the following steps: Example 1
[0031] Step 1: By mass, add 60 parts of carbonyl iron powder to 250 parts of 0.1 mol / L hydrochloric acid solution, mix ultrasonically for 30 minutes until uniform, filter, wash with anhydrous ethanol 3 times, and then dry the carbonyl iron powder completely at 60°C to clean the oxide on the surface of the carbonyl iron powder and allow the active hydroxyl group to attach to the surface of the iron powder.
[0032] Step 2: By mass, 50 parts of the carbonyl iron powder obtained in step 1, 100 parts of anhydrous ethanol and 15 parts of methacrylic acid are mixed in a reaction container and filtered. After washing with anhydrous ethanol for 3 times, the powder is vacuum dried at 60°C for 12 hours until complete, so that double bonds are introduced on the surface of the carbonyl iron powder, which is used to graft monomers containing self-healing structures.
[0033] Step 3: Mix 10 parts by mass of the carbonyl iron powder obtained in step 2, 4 parts of polyvinyl pyrrolidone and 100 parts of anhydrous ethanol in a reaction container to obtain a dispersion system A.
[0034] 3 parts by mass of ethoxylated trimethylolpropane triacrylate, 3 parts of 2-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-one)-ureido)ethyl methacrylate, 3 parts of N,N'-(dithiodiylbis(4,1-phenylene))bis(2-methylacrylamide), 0.04 parts of azobisisobutyronitrile and 10 parts of dimethylformamide were ultrasonically mixed to obtain a mixed solution B.
[0035] Step 4: Under nitrogen and reflux conditions, the dispersion system A prepared in step 3 is heated to 60°C, and the mixed solution B prepared in step 3 is added dropwise at a stirring rate of 400 rpm. After the addition is completed, the solution polymerization reaction is continued until the cross-linking reaction of the two is complete. The mass ratio of the dispersion system A to the mixed solution B is 3:1.
[0036] Step 5: Filter the mixed liquid after the reaction in step 4 is complete to obtain a powder. Wash the powder with 50 parts of dimethylformamide and 50 parts of anhydrous ethanol in turn, and then vacuum dry it at 60°C for 12 hours to obtain repairable resin-coated carbonyl iron powder.
[0037] Under nitrogen and reflux conditions, 5 parts of polyethylene glycol 1000, 0.8 parts of bis(2-hydroxyethyl) disulfide, 2 parts of 1-(6-(3-(1,3-dihydroxy-2-methylpropane-2-yl)urea)hexyl)-3-(6-methyl-4-oxo-1,4-dihydropyridin-2-yl)urea, 4 parts of isophorone diisocyanate, 0.03 parts of dibutyltin dilaurate and 10 parts of anhydrous dimethylformamide were reacted at 60°C for 5 hours to obtain a mixed solution C, which is the matrix of the self-healing composite material.
[0038] Step 6: Evenly mix 10 parts of the mixed solution C obtained in step 5 and 1 part of the repairable resin-coated carbonyl iron powder, and dry completely at 80° C. to obtain a self-repairable electromagnetic composite material.
[0039] Example 2
[0040] Step 1: By mass, add 60 parts of carbonyl iron powder to 250 parts of 0.1 mol / L hydrochloric acid solution, mix well, filter, wash with anhydrous ethanol three times, and then dry the carbonyl iron powder completely at 60°C.
[0041] Step 2: By mass, 50 parts of the carbonyl iron powder obtained in step 1, 100 parts of anhydrous ethanol and 15 parts of methacrylic acid are mixed evenly in a reaction container, filtered, washed with anhydrous ethanol three times, and then the powder is completely dried at 60°C.
[0042] Step 3: By weight, 10 parts of the carbonyl iron powder obtained in step 2, 4 parts of polyvinyl pyrrolidone and 100 parts of anhydrous ethanol are mixed uniformly in a reaction container to obtain a dispersion system A;
[0043] By mass, 6 parts of ethoxylated trimethylolpropane triacrylate, 6 parts of 2-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-one)-ureido)ethyl methacrylate, 6 parts of N,N'-(dithiodiylbis(4,1-phenylene))bis(2-methylacrylamide), 0.08 parts of azobisisobutyronitrile and 20 parts of dimethylformamide were uniformly mixed by ultrasonication to obtain a mixed solution B;
[0044] Step 4: Under nitrogen and reflux conditions, the dispersion system A prepared in step 3 is heated to 60°C, and the mixed solution B prepared in step 3 is added dropwise under a mechanical stirring rate of 400 rpm. After the addition is completed, the solution polymerization reaction is continued. The reaction is continued for 6 hours until the cross-linking reaction of the two is complete. The mass ratio of the dispersion system A to the mixed solution B is 3:1.
[0045] Step 5: Filter the mixed liquid after the reaction in step 4 is complete to obtain a powder. Wash the powder with 50 parts of dimethylformamide and 50 parts of anhydrous ethanol in turn, and then vacuum dry it at 60°C for 12 hours until it is completely dry to obtain repairable resin-coated carbonyl iron powder.
[0046] Under nitrogen and reflux conditions, 5 parts of polyethylene glycol 1000, 0.8 parts of bis(2-hydroxyethyl) disulfide, 2 parts of 1-(6-(3-(1,3-dihydroxy-2-methylpropane-2-yl)urea)hexyl)-3-(6-methyl-4-oxo-1,4-dihydropyridin-2-yl)urea, 4 parts of isophorone diisocyanate, 0.03 parts of dibutyltin dilaurate and 10 parts of anhydrous dimethylformamide were reacted at 60°C for 5 hours to obtain a mixed solution C, which is the matrix of the self-healing composite material.
[0047] Step 6: Evenly mix 10 parts of the mixed solution C obtained in step 5 and 1 part of the repairable resin-coated carbonyl iron powder, and dry completely at 80° C. to obtain a self-repairable electromagnetic composite material.
[0048] Example 3
[0049] Step 1: By mass, add 60 parts of carbonyl iron powder to 250 parts of 0.1 mol / L hydrochloric acid solution, mix well (ultrasonic mixing for 30 minutes), filter, wash with anhydrous ethanol three times, and then vacuum dry the carbonyl iron powder at 60°C for 12 hours until it is completely dry.
[0050] Step 2: By mass, 50 parts of the carbonyl iron powder obtained in step 1, 100 parts of anhydrous ethanol and 15 parts of methacrylic acid are mixed in a reaction container (ultrasonic mixing for 30 minutes), filtered, washed with anhydrous ethanol three times, and then the powder is vacuum dried at 60°C for 12 hours until completely dry.
[0051] Step 3: By weight, 10 parts of the carbonyl iron powder obtained in step 2, 4 parts of polyvinyl pyrrolidone and 100 parts of anhydrous ethanol are mixed uniformly in a reaction container to obtain a dispersion system A;
[0052] By mass, 9 parts of ethoxylated trimethylolpropane triacrylate, 9 parts of 2-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-one)-ureido)ethyl methacrylate, 9 parts of N,N'-(dithiodiylbis(4,1-phenylene))bis(2-methylacrylamide), 0.12 parts of azobisisobutyronitrile and 30 parts of dimethylformamide were uniformly mixed by ultrasonication to obtain a mixed solution B;
[0053] Step 4: Under nitrogen and reflux conditions, the dispersion system A prepared in step 3 is heated to 60°C, and the mixed solution B prepared in step 3 is added dropwise at a stirring rate of 400 rpm. After the addition is completed, the solution polymerization reaction is continued until the cross-linking reaction of the two is complete. The mass ratio of the dispersion system A to the mixed solution B is 4:1.
[0054] Step 5: Filter the mixed liquid after the reaction in step 4 is complete to obtain a powder. Wash the powder with 50 parts of dimethylformamide and 50 parts of anhydrous ethanol in turn, and then vacuum dry it at 60°C for 12 hours until it is completely dry to obtain repairable resin-coated carbonyl iron powder.
[0055] Under nitrogen and reflux conditions, 5 parts of polyethylene glycol 1000, 0.8 parts of bis(2-hydroxyethyl) disulfide, 2 parts of 1-(6-(3-(1,3-dihydroxy-2-methylpropane-2-yl)urea)hexyl)-3-(6-methyl-4-oxo-1,4-dihydropyridin-2-yl)urea, 4 parts of isophorone diisocyanate, 0.03 parts of dibutyltin dilaurate and 10 parts of anhydrous dimethylformamide were reacted at 60°C for 5 hours to obtain a mixed solution C, which is the matrix of the self-healing composite material.
[0056] Step 6: Evenly mix 10 parts of the mixed solution C obtained in step 5 and 1 part of the repairable resin-coated carbonyl iron powder, and dry completely at 80° C. to obtain a self-repairable electromagnetic composite material.
[0057] Figure 1 Scanning electron microscope photographs (X-scattering mode) of the coating layers of the cross-linked resin-coated carbonyl iron powder prepared in Examples 1-3 of the present invention with thicknesses from thin to thick.
[0058] Figure 2 The X-ray photoelectron spectra of the uncoated carbonyl iron powder and the cross-linked resin coated carbonyl iron powder prepared in Example 2. In Example 2, N1S and S2P peaks were found but Fe2P peak was not found, indicating that the carbonyl iron powder was completely coated by the cross-linked resin.
[0059] Figure 3 The electrochemical corrosion Tafel curves of the carbonyl iron powder before coating and the carbonyl iron powders with different coating thicknesses prepared in Examples 1 to 3 in 3.5% sodium chloride aqueous solution are shown in Figure 1. The results show that the corrosion resistance of the cross-linked resin coated carbonyl iron powder is greatly improved compared with that of the uncoated carbonyl iron powder.
[0060] Figure 4 (a) is an optical microscope photograph of the composite material prepared in Example 2 taken when completely cut; Figure 4 (b) is an optical microscope photo of the cut composite material repaired at 60°C for 1 h, showing that the crack has begun to heal; Figure 4 (c) is an optical microscope photograph of the cut composite material repaired at 60°C for 2 h, and the cracks have been basically completely repaired.
[0061] Figure 5 The stress-strain curves of the composite material prepared in Example 2 before and after repair; it can be seen from the curve that after the cut composite material was repaired at 60°C for 1 hour, the self-healing efficiency based on elongation and strength reached 75% and 86% respectively; after repairing for 2 hours, the self-healing efficiency based on elongation and strength reached 88% and 85% respectively. The above data show that the composite material prepared by the present invention has excellent self-healing function, and thus has better corrosion resistance than the existing electromagnetic composite material, and is expected to be widely used under more complex conditions.
[0062] Figure 6 (a) is the three-dimensional simulated reflection loss diagram of uncoated carbonyl iron powder. The maximum loss value of the sample is -42.38dB, and the maximum absorption bandwidth is 6.56GHz; Figure 6(b) is a three-dimensional simulated reflection loss diagram of carbonyl iron powder prepared in Example 1. The maximum loss value of the sample is -43.72dB, and the maximum absorption bandwidth is 7.79GHz. The above data show that the maximum loss value of the coated carbonyl iron powder prepared by the present invention is not much different from that of the sample before coating, but the maximum absorption bandwidth increases, indicating that the microwave absorption performance of the carbonyl iron powder prepared by the present invention is better than that of the uncoated carbonyl iron powder.
[0063] According to the above embodiments, the present invention uses a free radical polymerization reaction in a solution to make the resin cross-linked network uniformly and densely coated on the surface of the carbonyl iron powder, and uses a polyurethane containing quadruple hydrogen bonds and disulfide bonds as a resin matrix, thereby preparing an electromagnetic composite material with excellent self-healing performance, which greatly improves the corrosion resistance of the electromagnetic composite material. The present invention provides a new idea for the long-standing problem that the absorbing coating is easily damaged in a complex environment, resulting in a sharp decline in performance, so that it can be better applied to multiple scenarios.
Claims
1. A method for preparing a self-repairable electromagnetic composite material, characterized in that: The following steps are involved: Step 1, by mass, add 60-70 parts of carbonyl iron powder to 250-300 parts of an acidic solution with a pH of 1-2, mix well, filter, wash with anhydrous ethanol 2-3 times, and then dry the carbonyl iron powder completely at a temperature below 60° C. to clean the oxide on the surface of the carbonyl iron powder and allow active hydroxyl groups to adhere to the surface of the iron powder; Step 2: Mix 50-60 parts of the carbonyl iron powder obtained in step 1, 100-120 parts of anhydrous ethanol and 15-20 parts of methacrylic acid in a reaction container, filter, wash with anhydrous ethanol 2-3 times, and then dry the obtained powder completely at a temperature below 60° C. to introduce double bonds on the surface of the dried carbonyl iron powder, so as to be used for grafting the monomer containing the self-healing structure; Step 3: Mix 10-20 parts by mass of the carbonyl iron powder obtained in step 2, 4-6 parts by mass of polyvinyl pyrrolidone and 80-100 parts by mass of anhydrous ethanol in a reaction container to obtain a dispersion system A; Mix 3-9 parts of ethoxylated trimethylolpropane triacrylate, 3-9 parts of 2-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-one)-ureido)ethyl methacrylate, 3-9 parts of N,N'-(dithiodiylbis(4,1-phenylene))bis(2-methylacrylamide), 0.04-0.12 parts of azobisisobutyronitrile and 10-30 parts of dimethylformamide, by mass, to obtain a mixed solution B; Step 4, under inert protective gas and reflux conditions, the dispersion system A prepared in step 3 is heated to 60-65° C., and the mixed solution B prepared in step 3 is added dropwise at a stirring rate of 400-450 rpm. After the dropwise addition is completed, the solution polymerization reaction is continued until the cross-linking reaction of the two is complete; the mass ratio of the dispersion system A to the mixed solution B is (3-4):1; Step 5, filtering the mixed solution after the reaction in step 4 is completed to obtain a powder, washing the obtained powder with at least 50 parts of dimethylformamide and at least 50 parts of anhydrous ethanol in sequence, and then drying it completely at a temperature not higher than 60° C. to obtain a repairable resin-coated carbonyl iron powder; In parts by mass, under inert protective gas and reflux conditions, 4-6 parts of polyethylene glycol 1000, 0.6-1 parts of bis(2-hydroxyethyl) disulfide, 1-3 parts of 1-(6-(3-(1,3-dihydroxy-2-methylpropane-2-yl)ureido)hexyl)-3-(6-methyl-4-oxo-1,4-dihydropyridin-2-yl)urea, 2-6 parts of isophorone diisocyanate, 0.02-0.06 parts of dibutyltin dilaurate and 10-30 parts of anhydrous dimethylformamide are reacted at 60-80° C. for 5 hours to obtain a mixed solution C, which is a matrix of a self-healing composite material; Step 6: Mix 10-30 parts of the mixed solution C obtained in step 5 and 1-3 parts of the repairable resin-coated carbonyl iron powder, by mass, and dry them completely at a temperature not lower than 80° C. to obtain a self-repairable electromagnetic composite material.
2. The method for preparing the self-repairable electromagnetic composite material according to claim 1, characterized in that: The acidic solution in step 1 is a 0.01-0.1 mol / L hydrochloric acid solution.
3. The method for preparing the self-repairable electromagnetic composite material according to claim 1, characterized in that: The inert protective gas in step 4 and step 5 is nitrogen.
4. The method for preparing the self-repairable electromagnetic composite material according to claim 1, characterized in that: The mixing in step 6 is carried out at room temperature in a beaker equipped with a mechanical stirrer at a rate of 100-120 rpm for 2 hours.
5. A self-repairable electromagnetic composite material, characterized in that: An electromagnetic wave absorbing material prepared by the method described in any one of claims 1 to 4 and used for military targets.