Conductive repair material, repair structure and preparation method

Abstract

The invention discloses a conductive repair material, a repair structure and a preparation method, and relates to the technical field of conductive repair. The conductive repair material comprises the following components in percentage by weight: 20-30 wt% of Ag (at) CeO2 (at) C three-layer core-shell structure conductive particles, 5-10 wt% of carboxylated CNT, 1-5 wt% of a dispersing agent and 3-5 wt% of an antioxidant, the coating is prepared from, by weight, 45-60% of fluorosilicone grafted epoxy resin, 1-3% of a coupling agent, 1-2% of chitosan and 4-6% of a curing agent. The repairing structure comprises an inner layer conductive repairing material and an outer layer ZnO / SiO2 passivation film. According to the repair material and the repair structure, dissolution and migration of Ag can be effectively reduced, the conductivity and stability of the material are remarkably improved, meanwhile, the adhesive force of the material is improved, the service life of the material is prolonged, the content of silver is low, and the cost is low.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of conductive repair, in particular to a conductive repair material, a repair structure and a preparation method. BACKGROUND

[0002] The conductive repair of the contact points of power equipment such as cable joints, knife switches and transformers needs to use a conductive repair material. The traditional conductive repair material is usually mainly composed of silver, a carbon carrier and a resin. The silver nanoparticles provide high conductivity, the carbon carrier constructs a conductive network, and the electronic tunneling effect restores the conductive path. However, the traditional conductive repair material has the following defects: 1. Poor conductive stability: due to the easy migration and aggregation of nano-silver particles, the difference in the thermal expansion coefficients of the epoxy resin matrix and the carbon carrier is large, and the interface peels off, resulting in the fracture of the conductive network of the traditional conductive repair material after thermal cycling (-40℃~120℃), and the contact resistance increases by >30% (for example, the resistance of a certain power grid increases from 0.01Ω to 0.13Ω after half a year of repair); 2. Failure in high temperature, high humidity and high pollution environment: in a humid environment (RH>85%), silver will be oxidized (Ag→Ag2O), the conductivity will decrease by >50%, and high temperature (>100℃) environment will cause resin degradation and adhesion loss ≥2 grades (ASTM D3359); at the same time, silver has high chemical activity and is easy to react with H2O / O2 to generate insulating oxides, and the resin has poor weather resistance and will hydrolyze and break the chain in a humid and hot environment; 3. Complex construction and high cost: the existing conductive repair material usually needs to be cured at high temperature (>150℃) or coated in a vacuum, and the qualified rate of field power repair is <60%; the high content of silver (>70wt%) leads to high cost; 4. Short service life: silver ions are easy to dissolve and migrate, and Ag2S insulating layer is generated in a sulfide environment (H2S), which shortens the service life by >70%. SUMMARY

[0003] The present application is to solve the technical problems that the existing conductive repair material has the problems of easy dissolution and migration of silver ions, poor conductive stability and short service life, poor adhesion in a complex environment, easy failure, and high content of silver ions leading to high cost, and aims to provide a conductive repair material, a repair structure and a preparation method. The repair material and the repair structure of the present application can effectively reduce the dissolution and migration of Ag⁺, significantly improve the conductivity and stability of the material, and improve the adhesion and service life of the material. The content of silver is low, and the cost is low.

[0004] The present application is realized by the following technical scheme.

[0005] The first object of the present application is to provide a conductive repair material, which comprises, by weight percentage: Group A: Ag@CeO2@C three-layer core-shell structure conductive particles 20-30 wt%, carboxylated CNT 5-10 wt%, dispersant 1-5 wt%, antioxidant 3-5 wt%; Group B: fluorosilicon grafted epoxy resin 45-60 wt%, coupling agent 1-3 wt%, chitosan 1-2 wt%, curing agent 4-6 wt%.

[0006] The application uses wavy carboxylated CNT as a carrier, increases mechanical interlocking points, can improve the interface bonding force with the resin matrix, thereby reducing the carbon carrier-matrix interface peeling, and guarantees the conductive stability. At the same time, Ag@CeO2@C three-layer core-shell structure conductive particles are used, an oxide shielding layer is formed by coating Ag with CeO2, the CeO2 coating layer can generate Ce2O3 by consuming environmental oxygen, block the diffusion of oxygen, reduce the oxidation and migration of silver, thereby avoiding the attenuation of conductivity, and the outer carbon layer further inhibits the migration of silver, better guarantees the conductive stability. Therefore, the application forms a double conductive network of "metallic conductive main path + carbon-based bridging secondary path" by combining conductive particles + carbon nanomaterials, and blocks oxygen by the CeO2 shielding layer, reduces the oxidation and migration of silver, and finally significantly improves the conductivity and stability of the material, while ensuring the anti-arc and anti-breakdown ability under high voltage electric field.

[0007] The application uses fluorosilicon grafted epoxy resin (15 wt% fluorosilicon segment), which is hydrophobically modified compared to traditional epoxy resin, can reduce water permeability, and improve the weather resistance of the material, thereby improving the adhesion of the material in complex environments.

[0008] The application adds chitosan, which can capture Ag + by ion chelation, reduce the dissolution and migration of Ag + , enhance the interface bonding performance, improve the conductive stability, and avoid the formation of Ag2S insulating layer in sulfide environment (H2S), thereby improving the service life of the material.

[0009] The application uses coupling agent, dispersant and other surface treatment methods to improve the interface force between metal particles and carbon-based materials, and between carbon-based and resin matrix, which can enhance the dispersibility and interface bonding force of the material, and improve the mechanical strength and service stability of the composite system.

[0010] To sum up, by adopting the wavy carboxylated CNT as the carrier, the Ag@CeO2@C three-layer core-shell structure conductive particle, adopting the fluorosilicon grafted epoxy resin as the matrix, and adding the chitosan, the dissolution and migration of Ag+ can be effectively reduced, the conductivity and stability of the material can be significantly improved, the adhesion and service life of the material are improved, the content of silver is less than 10%, compared with the high-silver formula in the prior art, the cost of the repair material of the application is also greatly reduced; the repair material can be applied to the repair of high-voltage conductive gaps of power equipment, the enhancement of the contact interface, the anti-arc and anti-breakdown protection and the like.

[0011] Further, the weight percentage comprises: A component: Ag@CeO2@C three-layer core-shell structure conductive particle 25 wt%, carboxylated CNT 8 wt%, dispersant 3 wt%, antioxidant 5 wt%; B component: fluorosilicon grafted epoxy resin 50 wt%, coupling agent 2 wt%, chitosan 2 wt%, curing agent 5 wt%.

[0012] Further, the preparation method of the Ag@CeO2@C three-layer core-shell structure conductive particle is: AgNO3 and Ce(NO3)3 are dissolved in deionized water, heated to 80-85℃, NaOH solution is added dropwise under stirring, the pH is adjusted to 9.0±0.2, and after reaction for 2-2.5h, centrifugation and washing are carried out to obtain Ag@CeO2 precursor slurry; 10-15 wt% of carbon source solution is added to the Ag@CeO2 precursor slurry, carbonization is carried out at 350-380℃ under nitrogen atmosphere for 1-1.5h, and after cooling, Ag@CeO2@C three-layer core-shell structure particles are obtained.

[0013] Further, the carbon source solution adopts glucose solution.

[0014] Further, the dispersant adopts PVP, the antioxidant adopts ascorbic acid, the coupling agent adopts KH-560, and the curing agent adopts TETA.

[0015] The second object of the application is to provide a preparation method of the conductive repair material, comprising the following steps: Ag@CeO2@C three-layer core-shell structure conductive particles, carboxylated CNT, dispersant and antioxidant are mixed in proportion to obtain a stable dispersed conductive phase A component; The fluorosilicon grafted epoxy resin, the coupling agent and the chitosan are mixed uniformly, the TETA curing agent is added, and a uniform matrix resin matrix phase B component is formed by stirring; Mixing A component and B component, stirring, vacuum degassing, to obtain conductive repair material.

[0016] The preparation process of the application is simple and controllable, suitable for large-scale production, and is conducive to reducing production cost.

[0017] Further, the stirring speed is 1500-2000 rpm, and the stirring time is 30-50 min each time.

[0018] A third object of the application is to provide a conductive repair structure comprising an inner layer and an outer layer, the inner layer being a repair layer coated with the conductive repair material according to any one of claims 1-5, and the outer layer material being a ZnO / SiO2 passivation film.

[0019] The application further coats a ZnO / SiO2 passivation film on the basis of the repair layer to form a combined repair structure of repair layer+passivation layer, and the ZnO / SiO2 passivation layer can further play a role in resisting sulfur corrosion and silver migration, avoiding the formation of an Ag2S insulating layer in a sulfide environment (H2S), prolonging the service life of the repair material, and improving the long-term service reliability of the material.

[0020] Further, the preparation method of the ZnO / SiO2 passivation film is as follows: Dissolve Zn(CH3COO)3·2H2O in ethanol, and add ethanolamine; Dissolve TEOS in water and adjust the pH to 2-4 for hydrolysis; Mix the two solutions at room temperature for 1-2 h to obtain a ZnO / SiO2 composite sol; Coat the ZnO / SiO2 composite sol on the surface of the repair layer to obtain a ZnO / SiO2 passivation film.

[0021] Further, the thickness of the ZnO / SiO2 passivation film is 50-100 nm.

[0022] Compared with the prior art, the application has the following advantages and beneficial effects.

[0023] 1. The present application uses wavy carboxylated CNT as a carrier, increases mechanical interlocking points, can improve the interfacial bonding force with the resin matrix, thereby reducing the carbon carrier-matrix interface peeling, ensuring the stability of the conductivity, at the same time, using Ag@CeO2@C three-layer core-shell structure conductive particles, forming an oxide shielding layer by coating Ag with CeO2, blocking the diffusion of oxygen, reducing the oxidation and migration of silver, thereby avoiding the attenuation of conductivity, the outer carbon layer further inhibits the migration of silver, better ensuring the stability of the conductivity; therefore, the present application forms a double conductive network of "metallic conductive main path + carbon-based bridging secondary path" by combining conductive particles + carbon nanomaterials, and blocks oxygen by combining CeO2 shielding layer, reduces the oxidation and migration of silver, and finally significantly improves the conductivity and stability of the material, while ensuring the anti-arc and anti-breakdown ability under high voltage electric field.

[0024] 2. The present application uses fluorosilicon grafted epoxy resin (15wt% fluorosilicon segment) for hydrophobic modification compared to traditional epoxy resin, which can reduce water permeability and improve the weather resistance of the material, thereby improving the adhesion of the material in complex environments.

[0025] 3. The present application adds chitosan, which can capture Ag + by ion chelation, reduce the dissolution and migration of Ag + , enhance the interfacial bonding performance, improve the conductivity stability, and avoid the formation of Ag2S insulating layer in sulfide environment (H2S), thereby improving the service life of the material and enhancing the long-term service reliability of the material.

[0026] 4. The present application uses wavy carboxylated CNT as a carrier, Ag@CeO2@C three-layer core-shell structure conductive particles, fluorosilicon grafted epoxy resin as a matrix, and adds chitosan, which can effectively reduce the dissolution and migration of Ag + , significantly improve the conductivity and stability of the material, while improving the adhesion and service life of the material, and the content of silver is less than 10%, compared with the high silver content formula in the prior art, the cost of the repair material of the present application is also greatly reduced; the repair material of the present application can be applied to special scenes such as repair of high-voltage conductive gap of power equipment, contact interface enhanced conductivity, anti-arc and anti-breakdown protection, etc. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the technical scheme of the present application is described below in conjunction with examples, it is obvious that the illustrative embodiments of the present application and the description thereof are only used to explain the present application, and not as a limitation of the present application.

[0028] The embodiments of the present application will be described in detail below, but there will be cases where unnecessary detailed descriptions are omitted. For example, there will be cases where detailed descriptions of matters known well and repeated descriptions are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art.

[0029] The ranges disclosed herein are made on an "open term" basis, given that a range is defined by selecting a lower limit and an upper limit, the selected lower limit and upper limit define the boundaries of the particular range. The ranges defined in this manner can be inclusive or exclusive of the endpoints, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range.

[0030] If not specifically stated, all the embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0031] If not specifically stated, all the technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0032] If not specifically stated, the "includes" and "contains" mentioned in the present application mean open-ended, and can also be closed. For example, the "includes" and "contains" can mean that other substances not listed can also be included or contained, or only the listed substances can be included or contained.

[0033] If not specifically stated, all the steps of the present application can be performed in sequence or randomly, and are preferably performed in sequence. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For example, the method can also include step (c), which means that step (c) can be added to the method in any order, for example, the method can include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0034] The technical solutions of the present application will be further described in detail below in combination with the examples.

[0035] It should be noted that the experimental methods used in the examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional in the art unless otherwise specified, and are available to those skilled in the art through commercial channels.

[0036] Example 1

[0037] A conductive repair material, comprising, by weight percentage: Group A: Ag@CeO2@C three-layer core-shell structure conductive particles 25 wt%, carboxylated CNT 8 wt%, dispersant PVP 3 wt%, antioxidant ascorbic acid 5 wt%; Group B: fluorosilicon grafted epoxy resin (15 wt% fluorosilicon segment) 50 wt%, coupling agent KH-560 2 wt%, chitosan 2 wt%, curing agent TETA 5 wt%.

[0038] The embodiment provides a preparation method of a conductive repair material, comprising the following steps: (1) AgNO3 and Ce(NO3)3 are dissolved in 500 mL deionized water at a molar ratio of 1:1, heated to 80°C, and NaOH solution is added dropwise under stirring to adjust the pH to 9.0 ± 0.2; after reaction for 2 h, centrifugation and washing are performed to obtain Ag@CeO2 precursor slurry; (2) 10-15 wt% carbon source solution is added to the Ag@CeO2 precursor slurry, and carbonization is performed at 350-380°C under a nitrogen atmosphere for 1-1.5 h, and after cooling, Ag@CeO2@C three-layer core-shell structure particles are obtained; (3) Ag@CeO2@C three-layer core-shell structure conductive particles, carboxylated CNT, dispersant and antioxidant are stirred at 2000 rpm for 30 min in a proportion to obtain a stably dispersed conductive phase A component; (4) The fluorosilicon grafted epoxy resin, coupling agent and chitosan are uniformly mixed, and the TETA curing agent is added and stirred at 2000 rpm for 30 min to form a uniform matrix resin matrix phase B component; (5) A component and B component are mixed and stirred at 2000 rpm for 30 min, and vacuum degassing is performed at -0.1 MPa for 5 min to obtain a conductive repair material.

[0039] The embodiment also provides a repair structure based on the above-mentioned conductive repair material, wherein the repair structure comprises an inner layer and an outer layer, the inner layer is a repair layer, and the conductive repair material is coated at a position to be repaired; and the outer layer material is a ZnO / SiO2 passivation film.

[0040] The preparation method of the ZnO / SiO2 passivation film is as follows: Zn(CH3COO)3·2H2O is dissolved in ethanol (0.05-0.1 mol / L), and an appropriate amount of ethanolamine is added as a stabilizer; TEOS is dissolved in water, and hydrolysis is performed by adjusting the pH to 2-4 with hydrochloric acid, and the two solutions are mixed and stirred at room temperature for 1 h to obtain a ZnO / SiO2 composite sol.

[0041] In use, the conductive repair material is coated at the position to be repaired, and then a ZnO / SiO2 composite sol is coated on the surface thereof, with the coating thickness controlled to be 50-100 nm, and the coating is cured at 60°C for 1 h to form a dense passivation film.

[0042] Example 2

[0043] The difference between this example and Example 1 is that the formulation of the conductive repair material is different, and includes, in terms of weight percentage: A component: Ag@CeO2@C three-layer core-shell structure conductive particles 22 wt%, carboxylated CNT 5 wt%, dispersant PVP 3 wt%, antioxidant ascorbic acid 3 wt%; B component: fluorosilicon grafted epoxy resin (15 wt% fluorosilicon segment) 60 wt%, coupling agent KH-560 2 wt%, chitosan 2 wt%, curing agent TETA 5 wt%.

[0044] Example 3

[0045] The difference between this example and Example 1 is that the formulation of the conductive repair material is different, and includes, in terms of weight percentage: A component: Ag@CeO2@C three-layer core-shell structure conductive particles 22 wt%, carboxylated CNT 5 wt%, dispersant PVP 3 wt%, antioxidant ascorbic acid 3 wt%; B component: fluorosilicon grafted epoxy resin (15 wt% fluorosilicon segment) 60 wt%, coupling agent KH-560 2 wt%, chitosan 2 wt%, curing agent TETA 5 wt%.

[0046] Comparative Example 1 The difference between this comparative example and Example 1 is that the Ag@CeO2@C three-layer core-shell structure conductive particles are replaced by Ag@C double-layer core-shell structure conductive particles, and the other conditions remain unchanged.

[0047] Comparative Example 2 The difference between this comparative example and Example 1 is that the carboxylated CNT is replaced by ordinary CNT, and the other conditions remain unchanged.

[0048] Comparative Example 3 The difference between this comparative example and Example 1 is that no chitosan is added, and the other conditions remain unchanged.

[0049] Comparative Example 4 The difference between this comparative example and Example 1 is that no ZnO / SiO2 passivation film layer is provided, and the other conditions remain unchanged.

[0050] The performance of the conductive repair structure obtained in the above embodiment 1 and comparative examples 1-3 was tested. According to the IEC 60502 standard, the 10kV cable joint coated with the conductive repair structure was subjected to thermal cycle test of -40℃ (1h) - 120℃ (1h), and the resistance change rate after 100 times of test was tested; the material volume resistivity was tested by the ASTM D257 method, the salt spray 96h adhesion test was performed according to the ASTM D3359 method, and the silver ion elution amount was tested by ICP-MS, and the results are shown in Table 1.

[0051] Table 1, performance test comparison results

[0052] From the data in Table 1, it can be seen that: Comparative example 1 does not contain CeO2, and the thermal cycle stability is obviously reduced, and the silver ion elution amount is obviously increased, and other performances are also deteriorated to a certain extent; comparative example 2 uses ordinary CNT, the structure of ordinary CNT is more straight, the defects are less, the surface functional groups are less, and the dispersion is poor, which leads to that the volume resistivity is obviously increased, the thermal cycle stability is obviously reduced, and other performances are also deteriorated to a certain extent; comparative example 3 does not add chitosan, the capture ability of Ag + is decreased, the interfacial bonding force is reduced, thereby leading to that the adhesion is obviously decreased, the silver ion elution amount is obviously increased, and other performances are also deteriorated to a certain extent; comparative example 4 has no ZnO / SiO2 passivation film layer, which mainly affects the silver migration and long-term stability, the silver ion elution amount is obviously increased, the adhesion is also decreased, and other performances are also deteriorated to a certain extent.

[0053] And embodiment 1 has good thermal cycle stability, low volume resistivity, good adhesion, and less silver ion elution amount, which proves that only under the synergistic effect of various aspects of the present application, the conductive repair material obtained can realize balanced excellent performance in all aspects.

[0054] Finally, it should be noted that: the above specific embodiments are only used to explain the purpose, technical scheme and beneficial effects of the present application in detail, and it should be understood that the above description is only a specific embodiment of the present application and does not limit the protection scope of the present application; although the present application has been described in detail with reference to the foregoing specific embodiments, those skilled in the art should understand that they can still modify the technical scheme recorded in the foregoing embodiments, or make equivalent replacement, improvement, etc. to part or all of the technical features; and these modifications, equivalent replacement, improvement do not make the essence of the corresponding technical scheme deviate from the scope of the technical scheme of the embodiments of the present application, and they should be covered in the scope of the claims and description of the present application.

Claims

1. An electrically conductive repair material, characterized in that, According to the weight percentage, comprising: A component: Ag@CeO2@C three-layer core-shell structure conductive particles 20-30 wt%, carboxylated CNT 5-10 wt%, dispersant 1-5 wt%, antioxidant 3-5 wt%; B component: fluorosilicon grafted epoxy resin 45-60 wt%, coupling agent 1-3 wt%, chitosan 1-2 wt%, curing agent 4-6 wt%.

2. The conductive repair material of claim 1, wherein According to the weight percentage, comprising: A component: Ag@CeO2@C three-layer core-shell structure conductive particles 25 wt%, carboxylated CNT 8 wt%, dispersant 3 wt%, antioxidant 5 wt%; B component: fluorosilicon grafted epoxy resin 50 wt%, coupling agent 2 wt%, chitosan 2 wt%, curing agent 5 wt%.

3. An electrically conductive repair material according to claim 1, wherein The preparation method of the Ag@CeO2@C three-layer core-shell structure conductive particles is: Dissolve AgNO3 and Ce(NO3)3 in deionized water, heat to 80-85℃, add NaOH solution dropwise under stirring, adjust pH to 9.0±0.2, centrifuge and wash after reaction for 2-2.5h to obtain Ag@CeO2 precursor slurry; Add 10-15 wt% carbon source solution to the Ag@CeO2 precursor slurry, carbonize at 350-380℃ under nitrogen atmosphere for 1-1.5h, and obtain Ag@CeO2@C three-layer core-shell structure particles after cooling.

4. An electrically conductive repair material according to claim 3, wherein The carbon source solution uses glucose solution.

5. The conductive repair material of claim 1, wherein The dispersant uses PVP, the antioxidant uses ascorbic acid, the coupling agent uses KH-560, and the curing agent uses TETA.

6. A method of preparing an electrically conductive repair material according to any one of claims 1 to 5, characterized in that, Comprising the following steps: Stir and mix Ag@CeO2@C three-layer core-shell structure conductive particles, carboxylated CNT, dispersant and antioxidant in proportion to obtain stably dispersed conductive phase A component; Mix fluorosilicon grafted epoxy resin, coupling agent and chitosan uniformly, add TETA curing agent, and stir to form a uniform matrix resin matrix phase B component; Mix A component and B component, stir, and vacuum degassing to obtain conductive repair material.

7. The method of claim 6, wherein the conductive repair material is prepared by mixing the conductive filler and the resin in a ratio of 1 : 1 to 1 :

3. The stirring speed is 1500-2000 rpm, and the stirring time is 30-50 min each time.

8. An electrically conductive repair structure, characterized by Comprising an inner layer and an outer layer, the inner layer is a repair layer coated by the conductive repair material according to any one of claims 1-5, and the outer layer material is a ZnO / SiO2 passivation film.

9. An electrically conductive repair structure according to claim 8, wherein, The preparation method of the ZnO / SiO2 passivation film is: Dissolve Zn(CH3COO)3·2H2O in ethanol and add ethanolamine; Dissolve TEOS in water and adjust pH to 2-4 for hydrolysis; Mix the two solutions under stirring at room temperature for 1-2h to obtain ZnO / SiO2 composite sol; Coat the ZnO / SiO2 composite sol on the surface of the repair layer to obtain a ZnO / SiO2 passivation film.

10. An electrically conductive repair structure according to claim 9, wherein, The thickness of the ZnO / SiO2 passivation film is 50-100 nm.

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