A ternary composite nanofiber for marine metal corrosion prevention and electromagnetic wave absorption, a preparation method and application thereof

Abstract

The application provides a ternary composite nanofiber for marine metal corrosion prevention and electromagnetic wave absorption, and a preparation method and application thereof. The preparation method of the ternary composite nanofiber comprises the following steps: (1) preparation of a precursor solution: dispersing copper salt and a cobalt compound in a first solvent, stirring until fully dissolved, adding a polymer, and uniformly mixing to obtain the precursor solution; (2) preparation of a nanofiber membrane: electrospinning the precursor solution to obtain a nanofiber membrane loaded with copper and cobalt metal ions; (3) carbonization: drying the nanofiber membrane, and performing high-temperature treatment after drying, so that the ternary composite nanofiber for marine metal corrosion prevention and electromagnetic wave absorption is obtained. The preparation method of the ternary composite nanofiber is simple, low in cost, and has great application prospect in electromagnetic wave shielding in marine and other corrosive environments.

Description

Technical Field

[0001] The present invention belongs to the technical field of marine metal anti-corrosion, and specifically relates to a ternary composite nanofiber that can be used for marine metal anti-corrosion and electromagnetic wave absorption, as well as a preparation method and application thereof. Background Art

[0002] Excellent electromagnetic wave absorbing materials must possess high absorption capacity and corrosion resistance. This is crucial for military stealth technology and electromagnetic interference mitigation, especially for their ability to operate in high-humidity, acidic, and alkaline environments. However, the development and application of traditional absorbing materials are limited by their high density, high matching thickness, and limited loss mechanisms. Once absorbing materials are subject to corrosion, their lifespan and absorption efficiency are significantly reduced.

[0003] Seawater contains a variety of inorganic salts, which can damage the performance of electromagnetic wave absorbing materials. Electromagnetic wave absorbing materials are generally used on the surface of metal substrates. Therefore, if electromagnetic wave absorbing materials have anti-corrosion properties, it can not only improve their application as electromagnetic wave absorbing materials in corrosive environments such as marine engineering, but also be used to prevent corrosion of metal substrates in marine engineering, thereby broadening the application scope of electromagnetic wave absorbing materials.

[0004] Therefore, it is necessary to provide an improved technical solution to the above-mentioned deficiencies in the prior art. Summary of the Invention

[0005] The purpose of the present invention is to provide a ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption, as well as its preparation method and application, so as to help make the electromagnetic wave absorbing material have anti-corrosion properties and broaden its application in marine engineering.

[0006] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions: A method for preparing a ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption, comprising the following steps: (1) preparation of a precursor solution: dispersing a copper salt and a cobalt compound in a first solvent, stirring until fully dissolved, adding a polymer, and mixing evenly to obtain the precursor solution; (2) preparation of a nanofiber membrane: electrospinning the precursor solution to obtain a nanofiber membrane loaded with copper and cobalt metal ions; (3) carbonization: drying the nanofiber membrane and performing a high-temperature treatment after drying to obtain the ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption; the high-temperature treatment includes a first stage and a second stage; the first stage: heating from room temperature to 200-250°C in an air atmosphere and keeping warm for 1.5-2h; the second stage: continuing to heat to 700-800°C in a nitrogen and / or rare gas atmosphere and keeping warm for 1.5-2h.

[0007] Preferably, the molar ratio of the copper salt to the cobalt compound is 1:(0.9-1.1), and the mass ratio of the polymer to the solvent is 3:(47-53).

[0008] Preferably, the copper salt is copper acetate, the cobalt compound is cobalt acetylacetonate; the first solvent is DMF; the polymer is polyacrylonitrile; and the mass ratio of copper acetate to DMF is (5-10):100.

[0009] Preferably, in step (2), during the electrospinning, the distance between the electrospinning needle and the receiver is 14-15 cm, the operating voltage is set to 8-12 kV, the injection speed is 0.01-0.03 mm / min, and the air humidity is 25%-30%.

[0010] Preferably, in step (3), the drying temperature is 60-70°C, and the drying time is 12-24h; the heating rate in the second stage is 5-7°C / min.

[0011] The present invention also provides a ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption, which adopts the following technical solution: a ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption, and the ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption is prepared by the method described above.

[0012] The present invention also provides a coating that can be used for marine metal corrosion protection and electromagnetic wave absorption, which adopts the following technical solution: a coating that can be used for marine metal corrosion protection and electromagnetic wave absorption, including a resin, a curing agent, a second solvent and the ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption as described above.

[0013] Preferably, the resin is epoxy resin, the curing agent is polyamide curing agent, and the mass ratio of the epoxy resin to the polyamide curing agent is 1:(0.5-1.2); the second solvent is ethanol, and the mass ratio of the epoxy resin to the ethanol is 1:(1.5-2.1); the mass ratio of the ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption to the epoxy resin is 1%-5%.

[0014] The present invention also provides a coating that can be used for marine metal corrosion protection and electromagnetic wave absorption, which adopts the following technical solution: a coating that can be used for marine metal corrosion protection and electromagnetic wave absorption, the coating is formed by drying the above-mentioned coating.

[0015] The present invention also provides a marine engineering component with dual functions of corrosion resistance and electromagnetic wave absorption, which adopts the following technical solution: a marine engineering component with dual functions of corrosion resistance and electromagnetic wave absorption, comprising a metal substrate, the surface of which is loaded with the coating described above.

[0016] Beneficial effects:

[0017] The present invention successfully loads conductive metal copper and magnetic metal cobalt into nanofibers through electrospinning technology. Then, the composite nanofibers are carbonized by a post-treatment technology of high-temperature carbonization of the nanofiber membrane obtained by electrospinning under nitrogen protection to prepare the ternary composite nanofibers (i.e., Cu / Co / C composite nanofibers) of the present invention that can be used for marine metal corrosion protection and electromagnetic wave absorption. Among them, by subjecting the nanofiber membrane to high-temperature carbonization treatment in a nitrogen environment, it helps to further improve its electrical conductivity and enhance its electromagnetic wave absorption performance. In addition, the chemical stability of the ternary composite nanofibers (i.e., Cu / Co / C composite nanofibers) obtained after carbonization is greatly improved, and they have excellent corrosion resistance (for example, acid and alkali corrosion resistance or salt spray corrosion resistance).

[0018] In addition, the present invention successfully loads metal particles on nanofibers through blending technology, which solves the shortcomings of nanofibers prepared by electrospinning technology, such as poor conductivity and single loss mechanism. The preparation process is simple and controllable, low cost, and the prepared ternary composite nanofibers have excellent electromagnetic wave absorption effect. In the field of electromagnetic wave absorption, especially for electromagnetic wave shielding in corrosive environments such as the ocean, it has great application prospects.

[0019] In the coating of the present invention, the ternary composite nanofibers can perfectly match the epoxy resin and can effectively fill the inherent defects of the organic coating. It can not only improve the overall flexibility of the coating, but also fill the micropore defects in the coating, cut off the penetration path of corrosive ions, and delay the occurrence of the corrosion process.

[0020] The ternary composite nanofiber of the present invention has a wide range of applications, is compatible with epoxy resin, has excellent electromagnetic wave absorption and corrosion resistance after being cured into a coating, and can be adapted to electromagnetic wave absorption work in corrosive environments such as the ocean. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings and the accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. Among them:

[0022] Figure 1 are transmission electron microscope images; among them, (a) is the transmission electron microscope image of the ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption of Example 1 (800°C), (b) is the transmission electron microscope image of the composite nanofiber of Comparative Example 1 (600°C), and (c) is the transmission electron microscope image of the ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption of Example 3 (700°C).

[0023] Figure 2 These are Raman graphs of the composite nanofibers of Example 1, Comparative Example 1, and Example 3 of the present invention.

[0024] Figure 3 1 and 2 are XRD patterns of the composite nanofibers of Example 1, Comparative Example 1 and Example 3 of the present invention.

[0025] Figure 4 , (a) is a hysteresis loop diagram of Example 1, Example 3 and Comparative Example 1, and (b) is a local enlarged diagram of (a).

[0026] Figure 5 are reflection loss diagrams; wherein, (a) is the reflection loss diagram of the composite nanofiber of comparative example 1, (b) is the reflection loss diagram of the ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption of embodiment 3, and (c) is the reflection loss diagram of the ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption of embodiment 1.

[0027] Figure 6 Figures 20 and 21 are the results of acid and alkali resistance tests and salt spray tests; wherein, (a) is a photograph of the Cu / Co / C composite nanofibers of Example 1 immersed in 3mmol / L NaOH solution, 3mmol / L HNO3 solution, ice water and room temperature water (the "supersonic" in the figure means that the fibers were immersed in room temperature water and subjected to an ultrasonic treatment for 20 minutes) for 72 hours; (b) is a photograph of the Cu / Co / C composite nanofibers of Example 1 immersed in 3mmol / L NaOH solution, 3mmol / L HNO3 solution, ice water and room temperature water (the "supersonic" in the figure means that the fibers were immersed in room temperature water and subjected to an ultrasonic treatment for 20 minutes) for 15 days (in (b), the arrangement order of the four solutions is the same as in (a)); (c) is a photograph of the coatings of Examples 1, 4, 5 and Comparative Example 2 of the present invention before and after the salt spray test.

[0028] Figure 7 Graphs showing electrochemical impedance spectroscopy results; (a) is the Nyquist plot of the coatings of Example 1 (5%), Example 4 (3%), Example 5 (1%), and Comparative Example 2 (EP) after 60 days of salt spray testing; (b) is a partially enlarged view of (a). DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention are within the scope of protection of the present invention.

[0030] The present invention will be described in detail below with reference to the embodiments. It should be noted that the embodiments and features of the embodiments of the present invention can be combined with each other without conflict.

[0031] The present invention addresses the problem that electromagnetic wave absorbing materials need to serve in environments prone to corrosion such as high humidity and high salt when used in marine engineering. The invention provides a method for preparing ternary composite nanofibers that can be used for marine metal corrosion protection and electromagnetic wave absorption. The ternary composite nanofibers that can be used for marine metal corrosion protection and electromagnetic wave absorption prepared by this method have anti-corrosion properties and are suitable for application in marine engineering.

[0032] The method for preparing a ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption according to an embodiment of the present invention comprises the following steps: (1) preparing a precursor solution: dispersing a copper salt and a cobalt compound in a first solvent, stirring until fully dissolved, adding a polymer, and mixing uniformly to obtain a precursor solution; (2) preparing a nanofiber membrane: electrospinning the precursor solution to obtain a nanofiber membrane loaded with copper and cobalt metal ions; (3) drying the nanofiber membrane and performing a high-temperature treatment after drying to obtain an electromagnetic wave absorption material that can be used for marine metal corrosion protection; the high-temperature treatment comprises a first stage and a second stage; the first stage (pre-oxidation): heating from room temperature to 200-250°C (for example, 200°C, 210°C, 220°C, 230°C, 240°C, or 250°C) in an air atmosphere, and keeping warm for 1.5-2h (for example, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2h). The second stage (carbonization): in a nitrogen or rare gas (e.g., helium) atmosphere, continue heating to 700-800°C (e.g., 700°C, 720°C, 740°C, 760°C, 780°C, or 800°C), and keep warm for 1.5-2h (e.g., 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2h). The first stage (pre-oxidation) of high-temperature treatment can partially oxidize elements such as hydrogen, oxygen, and nitrogen in the polymer fiber to form oxides with a high oxygen content, thereby reducing the amount of gas released during the carbonization of the ternary composite nanofiber (i.e., Cu / Co / C composite nanofiber), reducing the internal stress and thermal shrinkage of the fiber during the carbonization process, and thus improving the carbonization efficiency; the purpose of the second stage (carbonization) of high-temperature treatment is to increase the mechanical strength and thermal stability of the ternary composite nanofiber (i.e., Cu / Co / C composite nanofiber) so that it can be used under high temperature and high strength conditions. By controlling the carbonization temperature and time, the thermal stability, density, and crystallinity of the fiber can be controlled, thereby obtaining carbon fibers with excellent microwave absorption properties. If the carbonization temperature deviates, the microwave absorption performance of the material may be reduced.

[0033] Electrospinning technology is an effective method for preparing fibrous polymer materials, and has the advantages of easy operation, short preparation cycle, and the ability to collect a large number of continuous long fibers. By changing the parameters, ultrafine fibers with diameters between nanometers and microns can be prepared. The unique interconnected fiber structure gives it a higher porosity, meeting the various requirements of composite fibers. Specific components can be compounded into nanofibers through blending technology to prepare a variety of composite materials. The present invention successfully loads conductive metal copper and magnetic metal cobalt into nanofibers through electrospinning technology, and then carbonizes the composite nanofibers by a post-treatment technology of high-temperature carbonization of the nanofiber membrane obtained by electrospinning under the protection of nitrogen or rare gas, thereby preparing the ternary composite nanofibers (i.e., Cu / Co / C composite nanofibers) of the present invention that can be used for marine metal corrosion protection and electromagnetic wave absorption. Among them, by subjecting the nanofiber membrane to high-temperature carbonization treatment in a nitrogen environment, it helps to further improve its electrical conductivity and enhance its electromagnetic wave absorption performance. The chemical stability of the ternary composite nanofiber (i.e., Cu / Co / C composite nanofiber) obtained after carbonization is greatly improved, and it has excellent corrosion resistance (for example, acid and alkali corrosion resistance or salt spray corrosion resistance).

[0034] In addition, the present invention successfully loads metal particles on nanofibers through blending technology, which solves the shortcomings of nanofibers prepared by electrospinning technology, such as poor conductivity and single loss mechanism. The preparation process is simple and controllable, and the cost is low. The prepared composite nanofibers have excellent electromagnetic wave absorption effect and have great application prospects in the field of electromagnetic wave absorption.

[0035] The preparation method of the ternary composite nanofiber for marine metal corrosion protection and electromagnetic wave absorption of the present invention is simple and low-cost. The prepared ternary composite nanofiber has great application prospects for electromagnetic wave shielding in corrosive environments such as the ocean.

[0036] In a preferred embodiment of the method for preparing ternary composite nanofibers that can be used for marine metal corrosion protection and electromagnetic wave absorption of the present invention, the molar ratio of copper salt to cobalt compound is 1:(0.9-1.1) (for example, 1:0.9, 1:0.95, 1:1, 1:1.05 or 1:1.1). Changing the molar ratio of copper to cobalt will cause changes in the material's micromorphology, electromagnetic parameters (dielectric constant, magnetic permeability), absorption bandwidth and impedance matching, thereby affecting the wave absorption effect. The mass ratio of polyacrylonitrile to the first solvent is 3:(47-53) (for example, 3:47, 3:48, 3:49, 3:50, 3:51, 3:52 or 3:53; preferably, when the mass ratio of polyacrylonitrile to the first solvent is 3:50, the electrospinning morphology effect is best).

[0037] In a preferred embodiment of the method for preparing ternary composite nanofibers for marine metal corrosion protection and electromagnetic wave absorption, the copper salt is copper acetate, the cobalt compound is cobalt acetylacetonate, the first solvent is DMF, the polymer is polyacrylonitrile, and the mass ratio of copper acetate to DMF is (5-10):100 (e.g., 5:100, 6:100, 7:100, 8:100, 9:100, or 10:100). DMF is a good solvent that can fully dissolve polyacrylonitrile.

[0038] In a preferred embodiment of the method for preparing ternary composite nanofibers for marine metal corrosion protection and electromagnetic wave absorption of the present invention, in step (2), during electrospinning, the distance between the electrospinning needle and the receiver is 14-15 cm (e.g., 14 cm, 14.3 cm, 14.6 cm, 14.8 cm or 15 cm), the operating voltage is set to 8-12 kV (e.g., 8 kV, 9 kV, 10 kV, 11 kV or 12 kV), the injection speed is 0.01-0.03 mm / min (e.g., 0.01 mm / min, 0.015 mm / min, 0.02 mm / min, 0.025 mm / min or 0.03 mm / min), and the air humidity is 25%-30% (e.g., 25%, 26%, 27%, 28%, 29% or 30%). Changes in the above parameters will result in changes in the diameter, morphology and structure of the filaments, thereby affecting the wave absorption performance of the product.

[0039] In a preferred embodiment of the method for preparing ternary composite nanofibers for marine metal corrosion protection and electromagnetic wave absorption of the present invention, in step (3), the drying temperature is 60°C-70°C (for example, 60°C, 62°C, 64°C, 66°C, 68°C or 70°C), and the drying time is 12-24h (for example, 12h, 16h, 20h or 24h); the heating rate in the second stage is 5-7°C / min (for example, 5°C / min, 6°C / min or 7°C / min). It should be noted that a heating rate that is too fast or too slow will affect the material's grain size, carbon content, and precipitation properties (a heating rate that is too fast will result in uneven carbonization; a heating rate that is too slow will result in uneven microscopic changes in the material, thereby affecting the wave absorption performance).

[0040] The present invention also proposes a ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption. The ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption in an embodiment of the present invention is prepared by the method described above.

[0041] The present invention also proposes a coating that can be used for marine metal corrosion protection and electromagnetic wave absorption. The coating that can be used for marine metal corrosion protection and electromagnetic wave absorption in an embodiment of the present invention includes a resin, a curing agent, a second solvent and the ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption as described above.

[0042] The coating formed by the coating for marine metal corrosion protection and electromagnetic wave absorption after drying has electromagnetic wave absorption performance and excellent corrosion resistance.

[0043] In a preferred embodiment of the coating that can be used for marine metal corrosion protection and electromagnetic wave absorption of the present invention, the resin is epoxy resin, the curing agent is polyamide curing agent, and the mass ratio of epoxy resin to polyamide curing agent is 1:(0.5-1.2) (for example, 1:0.5, 1:0.7, 1:0.8, 1:1 or 1:1.2); the second solvent is ethanol, and the mass ratio of epoxy resin to ethanol is 1:(1.5-2.1) (for example, 1:1.5, 1:1.7, 1:1.9, 1:2 or 1:2.1); the mass ratio of the ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption to the epoxy resin is 1%-5% (for example, 1%, 2%, 3%, 4% or 5%).

[0044] In the coating of the present invention, the ternary composite nanofibers can perfectly match the epoxy resin and can effectively fill the inherent defects of the organic coating. It can not only improve the overall flexibility of the coating, but also fill the micropore defects in the coating, cut off the penetration path of corrosive ions, and delay the occurrence of the corrosion process.

[0045] The ternary composite nanofiber of the present invention has a wide range of applications, is compatible with epoxy resin, has excellent electromagnetic wave absorption and corrosion resistance effects after being cured into a coating, and can be adapted to electromagnetic wave absorption work in a corrosive environment.

[0046] The present invention also proposes a coating that can be used for marine metal corrosion protection and electromagnetic wave absorption. The coating that can be used for marine metal corrosion protection and electromagnetic wave absorption in an embodiment of the present invention is formed by drying the coating as described above.

[0047] Preferably, the thickness of the coating that can be used for marine metal corrosion protection and electromagnetic wave absorption according to the embodiment of the present invention is 80-130 μm (for example, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm or 130 μm).

[0048] The present invention also proposes a marine engineering component with dual functions of corrosion protection and electromagnetic wave absorption. The marine engineering component with dual functions of corrosion protection and electromagnetic wave absorption in the embodiment of the present invention includes a metal substrate, and the surface of the metal substrate is loaded with the coating as described above, which improves the corrosion resistance while maintaining the wave absorbing performance. For example, in areas with tropical marine climates, the radar absorbing coatings of modern air force weapons are very susceptible to corrosion due to environmental influences. How to improve the corrosion resistance of the material while ensuring its wave absorbing performance has become a hot issue. The coating that can be used for marine metal corrosion protection and electromagnetic wave absorption of the present invention helps to solve or improve the equipment that needs to use radar absorbing coatings in tropical marine climate areas.

[0049] Preferably, the metal substrate may be carbon steel (eg, Q235).

[0050] The following describes in detail the ternary composite nanofibers for marine metal corrosion protection and electromagnetic wave absorption, as well as their preparation method and applications through specific examples.

[0051] In the following examples, the epoxy resin used is E-44 (6101) epoxy resin produced by Zhenjiang Danbao Resin Co., Ltd.; the curing agent is 650 low molecular weight polyamide curing agent produced by Dingyuan County Danbao Resin Co., Ltd.

[0052] Example 1

[0053] The ternary composite nanofibers of this embodiment, which can be used for marine metal corrosion protection and electromagnetic wave absorption, are prepared by a method comprising the following steps:

[0054] (1) Preparation of electrospinning precursor solution

[0055] 1.4 g of copper acetate and 1.8 g of cobalt acetylacetonate powder were weighed, dissolved in 20 g of N,N-dimethylformamide solution, stirred evenly, and then 1.2 g of polyacrylonitrile was added thereto. After stirring at room temperature (25°C) for 12 h, a dark green spinning solution was obtained.

[0056] (2) Preparation of nanofiber membranes

[0057] The spinning solution obtained in step (1) was injected into a 10 mL plastic syringe and, after fixing, the spinning needle was connected to the positive electrode. A piece of aluminum foil was covered on the collector, and electrospinning was performed. The distance between the positive and negative electrodes was adjusted to 14 cm. The electrospinning operating voltage was 12 kV, the injection speed was 0.02 mm / min, the temperature was 25°C, and the humidity was 27%. The spinning time was 12 h to obtain a nanofiber membrane loaded with Cu and Co metal ions.

[0058] (3) Carbonization

[0059] Remove the nanofiber membrane from the electrospinning machine and place it together with the aluminum foil in a constant temperature drying oven at 70°C for 12 hours; tear the nanofiber membrane from the aluminum foil and place it in a magnetic boat, and heat it in a tubular furnace under nitrogen protection:

[0060] The first stage: heating from room temperature to 200℃ in air atmosphere, keeping warm for 1h;

[0061] The second stage: in a nitrogen atmosphere, heating to 800°C at a rate of 5°C / min and keeping warm for 2 hours; finally, a black fiber is obtained, which is the ternary composite nanofiber (Cu / Co / C composite nanofiber) of this embodiment that can be used for marine metal corrosion protection and electromagnetic wave absorption.

[0062] The coating of this embodiment that can be used for marine metal corrosion protection and electromagnetic wave absorption includes 1g of epoxy resin (water-based epoxy resin), 0.8g of curing agent, 2mL of ethanol and 0.05g of ternary composite nanofiber (Cu / Co / C composite nanofiber) of this embodiment that can be used for marine metal corrosion protection and electromagnetic wave absorption.

[0063] The coating for marine metal corrosion protection and electromagnetic wave absorption of this embodiment is prepared by dissolving 1g of epoxy resin (water-based epoxy resin) and 0.8g of curing agent in 2mL of anhydrous ethanol, stirring evenly, and then mixing with 0.05g of Cu / Co / C composite nanofibers.

[0064] The marine metal anti-corrosion and electromagnetic wave absorption coating of this embodiment is obtained by evenly coating the aforementioned marine metal anti-corrosion and electromagnetic wave absorption coating on a metal substrate and drying the coating until the coating reaches a surface-dry state. In this embodiment, the final coating thickness is 80 μm.

[0065] Example 2

[0066] The only difference between this embodiment and Example 1 is that the water-based epoxy resin and the low-molecular polyamide curing agent are mixed in a mass ratio of 5:4, and the ternary composite nanofibers prepared in Example 1 that can be used for marine metal corrosion protection and electromagnetic wave absorption (the mass is 5% of the water-based epoxy resin) are added to obtain the coating that can be used for marine metal corrosion protection and electromagnetic wave absorption in this embodiment.

[0067] The coating that can be used for marine metal corrosion protection and electromagnetic wave absorption in this embodiment: the coating as described above is evenly coated on a metal substrate (Q235 carbon steel) using a glass rod, applied three times, and then placed in an oven at 60°C for 20 minutes. When the coating reaches a surface-dry state, the coating that can be used for marine metal corrosion protection and electromagnetic wave absorption in this embodiment is obtained (the thickness of the coating that can be used for marine metal corrosion protection and electromagnetic wave absorption in this embodiment is 100 μm).

[0068] Example 3

[0069] The ternary composite nanofibers for marine metal corrosion protection and electromagnetic wave absorption of this embodiment differ from those of Example 1 only in that in step (3), the temperature is heated to 700° C. during the second stage of carbonization; the rest are consistent with Example 1.

[0070] Example 4

[0071] The only difference between the coating for marine metal corrosion protection and electromagnetic wave absorption in this comparative example and Example 2 is that the mass of the ternary composite nanofiber for marine metal corrosion protection and electromagnetic wave absorption in the coating is 3% of the water-based epoxy resin; the rest is consistent with Example 2.

[0072] Example 5

[0073] The coating for marine metal corrosion protection and electromagnetic wave absorption in this embodiment differs from that in Example 2 only in that the mass of the ternary composite nanofibers for marine metal corrosion protection and electromagnetic wave absorption in the coating is 1% of the water-based epoxy resin; the rest is consistent with Example 2.

[0074] Comparative Example 1

[0075] The only difference between the composite nanofibers of this comparative example and Example 1 is that in step (3), the temperature is heated to 600° C. during the second stage of carbonization; the rest are consistent with Example 1.

[0076] Comparative Example 2

[0077] The coating of this comparative example differs from that of Example 1 only in that the ternary composite nanofibers prepared in Example 1 and capable of being used for marine metal corrosion protection and electromagnetic wave absorption are not added to the coating; the rest are consistent with Example 2.

[0078] Experimental example

[0079] 1. The performance of the ternary composite nanofibers for marine metal corrosion protection and electromagnetic wave absorption prepared in Example 1 and Comparative Examples 1 and 2 was tested:

[0080] 1) Transmission electron microscopy (TEM)

[0081] Each sample was observed under a transmission electron microscope ( Figure 1 ).in, Figure 1 (a) is the composite nanofiber formed at a carbonization temperature of 800°C (Example 1), with a fiber diameter of about 90 nm; Figure 1 (b) is the composite nanofiber formed at a carbonization temperature of 600°C (Comparative Example 1), with a fiber diameter of about 150 nm; Figure 1(c) shows the composite nanofiber formed at a carbonization temperature of 700°C (Example 3). As can be seen from the figure, the fiber diameter is about 150 nm.

[0082] 2) Raman

[0083] Raman spectra of Cu / Co / C composite nanofibers Figure 2 As shown; among them, 1340cm -1 The D peak at 1580 cm -1 The G peaks of the D and G peaks are used to represent amorphous carbon and graphitic carbon, respectively, and the peak intensity ratio of the D and G peaks (I D / I G ) can be used to evaluate the degree of graphitization of carbon. The smaller the ratio, the higher the degree of graphitization. Figure 2 The peak ratios of the composite nanofibers formed at carbonization temperatures of 600° C. (Comparative Example 1), 700° C. (Example 3), and 800° C. (Example 1) are quantitatively calculated to be 1.37, 1.1, and 1.03, respectively.

[0084] It can be seen that with the increase of carbonization temperature (carbonization temperature of the second stage), I D / I G The value gradually decreases, and the carbonization degree of the composite nanofibers gradually increases.

[0085] 3) X-ray diffraction (XRD)

[0086] Figure 3 The XRD patterns of the composite nanofibers obtained in Example 1 (800°C), Comparative Example 1 (600°C), and Example 3 (700°C) show that the crystallinity of Cu and Co on the fibers gradually increases with the increase of carbonization temperature.

[0087] 4) Magnetic strength test

[0088] The hysteresis loops of the three samples of Example 1, Example 3 and Comparative Example 1 were tested by VSM at room temperature under a ±2T magnetic field. Figure 4 shown.

[0089] Both Example 3 and Example 1 exhibit typical moderate ferromagnetism, while Comparative Example 1 (600°C) still exhibits an unsaturated magnetization state under a 2T magnetic field, indicating the presence of paramagnetic components in the sample. This result shows that the composite nanofibers formed in Comparative Example 1 are not completely carbonized and decomposed. The saturation magnetization values ​​of the three samples with carbonization temperatures of 600°C (Comparative Example 1), 700°C (Example 3) and 800°C (Example 1) are 16.4emu / g, 9.2emu / g and 5.1emu / g, respectively. As the carbonization temperature increases, the proportion of non-magnetic components in the composite fibers increases, and the mass percentage of magnetic Co decreases, resulting in a gradual downward trend in the saturation magnetization value of the material, indicating that the sample has lower magnetic permeability and magnetic loss capacity. The coercive forces of the three samples carbonized at 600°C, 700°C, and 800°C were 50 Oe, 37.5 Oe, and 34.1 Oe, respectively, which are higher than the coercive force of cobalt (~10 Oe). This significant improvement is due to the size effect and the enhancement of the surface anisotropic field. The higher coercive force is conducive to obtaining a relatively high natural resonance frequency. The enhancement of the coercive force will cause the resonance peak to move from MHz to GHz, which ensures the absorption of electromagnetic waves in the studied frequency band.

[0090] 5) Electromagnetic wave reflection loss test

[0091] The reflection losses of Example 1, Comparative Example 1 and Example 3 in the frequency range of 2-18 GHz were analyzed. Figure 5 RL curves of electromagnetic wave absorbing materials prepared by mixing 20 wt % of different samples with 80 wt % of paraffin wax. The thickness of each sample is set to 1-5 mm.

[0092] Quantitative analysis shows that the three-dimensional RL value of the composite nanofiber prepared in Comparative Example 1 ( Figure 5 (a)) is almost always greater than -10dB within the test range, which indicates that the composite nanofibers prepared at a carbonization temperature of 600°C cannot meet the requirements of electromagnetic wave absorption.

[0093] Figure 5 (b) and (c) are the three-dimensional RL value curves of Example 3 (carbonization temperature 700°C) and Example 1 (carbonization temperature 800°C), respectively. The two samples can effectively absorb electromagnetic waves. The RL value of Example 3 (carbonization temperature 700°C) at 17.12 GHz is min The value is -33.9dB, the matching thickness is only 1.3mm, and the maximum absorption bandwidth is 6.37GHz (11.6-18GHz) when the sample thickness is 1.5mm (RL≤10dB, 90% of the electromagnetic waves are absorbed); Example 1 (carbonization temperature 800℃) at 8GHz RL minThe value is -44.74dB, and the matching thickness is only 2.7mm. Example 1 (carbonization temperature 800°C) has a maximum absorption bandwidth of 6.8GHz (11.2-18GHz) when the thickness is 1.5mm.

[0094] The results show that the RL of Example 1 min The value is the smallest among the three samples. It has the advantages of strong absorption, thin matching thickness, and wide absorption bandwidth, and is a good electromagnetic absorption material.

[0095] 2. The corrosion resistance of the coatings for marine metal corrosion protection and electromagnetic wave absorption of Examples 1, 4 and 5 and the coating prepared in Comparative Example 2 was tested:

[0096] 1) Acid and alkali resistance test

[0097] The Cu / Co / C composite nanofibers of Example 1 were immersed in 3 mmol / L NaOH solution, 3 mmol / L HNO3 solution, ice water and room temperature water (ultrasound treatment was also performed for 20 min when immersed in room temperature water) for 72 h. After the immersion, each solution remained transparent (see Figure 6 (a)), indicating that the Cu / Co / C composite nanofibers of the present invention have excellent mechanical properties.

[0098] The Cu / Co / C composite nanofibers of Example 1 were immersed in 3mmol / L NaOH solution, 3mmol / L HNO3 solution, ice water and room temperature water (ultrasound treatment was also performed for 20 minutes when immersed in room temperature water) for 15 days (see Figure 6 (b); Figure 6 In (b), the arrangement order of the four solutions is the same as in (a). After immersion for 15 days, no visible changes in the solutions occurred, proving that the Cu / Co / C composite nanofibers can still have an absorbing effect after corrosion, indicating that the Cu / Co / C composite nanofibers have excellent acid and alkali resistance and corrosion resistance.

[0099] 2) Salt spray test

[0100] The coatings for marine metal corrosion protection and electromagnetic wave absorption of Example 1 (5%), Example 4 (3%) and Example 5 (1%) and the coating of Comparative Example 2 (pure epoxy) were respectively coated on metal substrates, and the coating thickness was controlled at 130 μm (±10 μm). A neutral salt spray test was carried out in a salt spray chamber (Japan SUGA cep-90) to evaluate the corrosion resistance of different samples.

[0101] The culture medium of the salt spray test is 5wt% NaCl solution, pH is 6.5-7.2, the test temperature is (35±2)°C, the spray pressure is between 0.1MPa-0.15MPa, and the inlet pressure is between 0.2MPa-0.4MPa.

[0102] After 60 days of salt spray test, all samples still maintained their intact surface ( Figure 6 (c)).

[0103] 3) Electrochemical testing

[0104] In order to further test the corrosion resistance of the sample, the coating (coating thickness 130 μm) after the 60-day salt spray test was subjected to electrochemical testing in a 3.5 wt % NaCl solution with an exposure time of 144 h.

[0105] The EIS results were obtained on an Autolab-PGSTAT302N electrochemical workstation using a three-electrode cell system with a coated steel block as the working electrode, a platinum plate electrode as the auxiliary electrode, and a saturated calomel electrode as the reference electrode. -2 ~10 5 The EIS data were tested in the Hz range with an RMS amplitude of 10 mV. To ensure the reliability and repeatability of the EIS data, at least three measurements were performed on the blank coating and the composite coating.

[0106] The test results are as follows Figure 7 As shown in the figure, as the amount of the ternary composite nanofiber that can be used for marine metal anticorrosion and electromagnetic wave absorption increases, the radius gradually increases. When the amount of the ternary composite nanofiber that can be used for marine metal anticorrosion and electromagnetic wave absorption is 3% (Example 4) and 5% (Example 1), the capacitive reactance arc of the coating is similar, which is much larger than that when the amount of the ternary composite nanofiber that can be used for marine metal anticorrosion and electromagnetic wave absorption is 0 (Comparative Example 2, Figure 7 The results show that the coatings of Example 5 have an impedance of 1-2 orders of magnitude higher than that of the coating of Comparative Example 1, indicating that the increased amount of the ternary composite nanofibers that can be used for marine metal corrosion protection and electromagnetic wave absorption in the coating is beneficial to enhancing the corrosion resistance of the coating.

[0107] In combination with the above 1)-3), it can be seen that the present invention can significantly increase the impedance of the coating and improve the corrosion resistance of the coating by adding ternary composite nanofibers that can be used for marine metal corrosion protection and electromagnetic wave absorption to the coating.

[0108] In summary, the present invention successfully prepared lightweight, wide-band absorption, and corrosion-resistant Cu / Co / C ternary composite nanofibers by combining electrospinning with high-temperature carbonization treatment. Thanks to the unique fiber structure, the synergistic effect of multiple loss mechanisms, good impedance matching and high attenuation capability, the ternary composite nanofibers (Cu / Co / C ternary composite nanofibers) of the present invention that can be used for marine metal corrosion protection and electromagnetic wave absorption exhibit excellent electromagnetic wave absorption effects. The size of the Cu / Co / C ternary composite nanofibers, the degree of crystallization of the agglomerates, the degree of graphitization, the matching thickness, the EAB and the RL values ​​can be adjusted by the carbonization temperature. In addition, the coating containing the Cu / Co / C ternary composite nanofibers also has good corrosion resistance. The results of the study show that the Cu / Co / C ternary composite nanofiber is an excellent electromagnetic absorption material and has the ability to work in harsh environments such as humidity, acid and alkali, and low temperature.

[0109] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing ternary composite nanofibers that can be used for marine metal corrosion protection and electromagnetic wave absorption, characterized in that: The steps include: (1) Preparation of a precursor solution: dispersing a copper salt and a cobalt compound in a first solvent, stirring until fully dissolved, adding a polymer, and mixing uniformly to obtain the precursor solution; (2) Preparation of nanofiber membrane: electrospinning the precursor solution to obtain a nanofiber membrane loaded with copper and cobalt metal ions; (3) Carbonization: drying the nanofiber membrane and subjecting it to high-temperature treatment after drying to obtain the ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption; The high temperature treatment includes a first stage and a second stage; The first stage: in air atmosphere, heat from room temperature to 200-250℃, keep warm for 1.5-2h; The second stage: in nitrogen and / or rare gas atmosphere, continue heating to 700-800℃ at a heating rate of 5-7℃ / min and keep warm for 1.5-2h; In step (1), the polymer is polyacrylonitrile; the molar ratio of the copper salt to the cobalt compound is 1:(0.9-1.1); In step (2), during the electrospinning, the distance between the electrospinning needle and the receiver is 14-15 cm, the operating voltage is set to 8-12 kV, the injection speed is 0.01-0.03 mm / min, and the air humidity is 25%-30%.

2. The method for preparing the ternary composite nanofiber for marine metal corrosion protection and electromagnetic wave absorption according to claim 1, characterized in that: The mass ratio of the polymer to the solvent is 3:(47-53).

3. The method for preparing the ternary composite nanofiber for marine metal corrosion protection and electromagnetic wave absorption according to claim 1, characterized in that: The copper salt is copper acetate, and the cobalt compound is cobalt acetylacetonate; The first solvent is DMF; The mass ratio of the copper acetate to DMF is (5-10):

100.

4. The method for preparing the ternary composite nanofiber for marine metal corrosion protection and electromagnetic wave absorption according to claim 1, characterized in that: In step (3), the drying temperature is 60-70°C and the drying time is 12-24 hours.

5. A ternary composite nanofiber that can be used for marine metal corrosion protection and electromagnetic wave absorption, characterized in that: The method is prepared by any one of claims 1 to 4.

6. A coating that can be used for marine metal corrosion protection and electromagnetic wave absorption, characterized in that: The invention comprises a resin, a curing agent, a second solvent and the ternary composite nanofibers as claimed in claim 5 that can be used for marine metal corrosion protection and electromagnetic wave absorption.

7. The coating for marine metal corrosion protection and electromagnetic wave absorption according to claim 6, characterized in that: The resin is an epoxy resin, the curing agent is a polyamide curing agent, and the mass ratio of the epoxy resin to the polyamide curing agent is 1:(0.5-1.2); The second solvent is ethanol, and the mass ratio of epoxy resin to ethanol is 1:(1.5-2.1); The mass of the ternary composite nanofibers that can be used for marine metal corrosion protection and electromagnetic wave absorption is 1%-5% of the mass of the epoxy resin.

8. A coating that can be used for marine metal corrosion protection and electromagnetic wave absorption, characterized in that: The coating layer is formed by drying the coating material according to claim 6 or 7.

9. A marine engineering component with dual functions of corrosion protection and electromagnetic wave absorption, characterized in that: It comprises a metal substrate, the surface of which is loaded with the coating according to claim 8.

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