Composite conductive material, paint and preparation method and application thereof

Abstract

The present application belongs to the technical field of paint, and particularly relates to a composite conductive material, paint, and a preparation method and application thereof. The composite conductive material has a core-shell structure; the core of the core-shell structure comprises graphite and nickel; the shell layer of the core-shell structure comprises polyaniline and a dopant; and the dopant comprises dodecyl benzene sulfonic acid. The composite conductive material with the core-shell structure is formed by taking graphite and nickel as the core and polyaniline as the shell. Through the synergistic effect of graphite, nickel and polyaniline, the paint can provide long-term protection under the complex environment of the grounding grid, the coating has strong corrosion resistance and excellent conductivity, and the coating has stable conductivity and large-current impact resistance, so as to ensure the safe and stable operation of the power facilities.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, and specifically relates to a composite conductive material, coating, preparation method and application thereof. Background Technology

[0002] The grounding grid is a critical infrastructure for the safe operation of power systems, responsible for discharging fault currents and lightning currents. Its reliability directly affects the stability of the power grid. However, in soils containing corrosive ions or acidic soils, grounding electrodes corrode severely, often leading to excessive grounding resistance or even breakage, posing a risk of equipment "losing ground." With the widespread adoption of ultra-high voltage (UHV) projects, higher requirements are placed on the long-term service performance of grounding grids, making corrosion protection an urgent issue for ensuring power grid safety.

[0003] Existing methods for corrosion protection of grounding grids have significant limitations. For example, the corrosion rate of galvanized steel increases significantly in harsh environments; after 1.4 years of burial in acidic soil, the corrosion rate can reach 6-8 g / dm³. 3 • The pitting rate reaches 0.7-1.3 mm / year, and the protection life is far below the design expectation of 30 years. Although copper has good corrosion resistance, it is expensive and resource-limited, with a material price 5-8 times that of steel, and there is a risk of heavy metal pollution in the soil. Cathodic protection systems require continuous monitoring and regular replacement of sacrificial anodes, resulting in high maintenance costs. The total life cycle cost can be 3-5 times the initial investment, and the protective effect decreases with changes in soil moisture and composition. These traditional methods are difficult to balance economy, environmental protection, and long-term effectiveness, and cannot meet the stringent requirements of the new generation of power grids for the reliability of grounding systems throughout their entire life cycle, forcing the industry to seek better solutions.

[0004] To address the aforementioned issues, developing specialized coatings that combine conductivity and corrosion resistance has become a new research direction. However, existing ordinary coatings have significant shortcomings in conductivity and resistance to high-current surges, with resistivity typically around 10⁻⁶. 6 Above Ω·cm, it cannot conduct fault current, and the coating is prone to carbonization and cracking under lightning current impact, making it difficult to meet the special requirements of the grounding grid to discharge kiloampere-level instantaneous current.

[0005] Therefore, it is of great significance to provide a coating with good conductivity, resistance to high current impact, and corrosion resistance. Summary of the Invention

[0006] The present invention aims to solve one or more technical problems existing in the prior art, and at least provide a beneficial solution. Specifically, the present invention provides a composite conductive material, the coating prepared from which has good conductivity, high current impact resistance, and corrosion resistance, and can solve the problems existing in current grounding grid protection.

[0007] The inventive concept of this invention is as follows: The composite conductive material of this invention has a core-shell structure; the core of the core-shell structure is composed of graphite and nickel; the shell of the core-shell structure is composed of polyaniline and a dopant, wherein the dopant is dodecylbenzenesulfonic acid.

[0008] This invention relates to a core-shell structured composite conductive material using graphite and nickel as the core and polyaniline and dopants as the shell. Graphite, due to its layered structure, provides an efficient electron conduction path, while nickel, with its excellent conductivity and corrosion resistance, complements the coating's conductivity. Polyaniline, as the conductive shell, not only provides excellent conductivity but also possesses electrochemical activity. When the metal matrix undergoes anodic dissolution, polyaniline preferentially accepts electrons and is reduced, inhibiting metal oxidation. Simultaneously, its p-type semiconductor properties cause the interface potential to shift positively to the passivation region, driving the regeneration of a dense oxide film. The controllable release of dopant ions further buffers the pH of the interface microregions, blocking active sites. This synergistic effect of redox buffering and electric field modulation allows polyaniline to maintain active protection even at coating defects. Through the synergistic effect of graphite, nickel, and polyaniline, the coating possesses excellent conductivity, conductive stability, resistance to high-current impacts, and corrosion resistance.

[0009] Therefore, a first aspect of the present invention provides a composite conductive material.

[0010] Specifically, the composite conductive material has a core-shell structure; The core of the core-shell structure is composed of graphite and nickel; The shell of the core-shell structure comprises polyaniline and dopants; The dopant includes dodecylbenzenesulfonic acid.

[0011] Preferably, the graphite has a particle size of 1-10 μm; for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc.

[0012] Preferably, the nickel has a particle size of 1-5 μm; for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, etc.

[0013] Preferably, the weight ratio of graphite to nickel is (3-9):1; for example, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, etc.

[0014] Preferably, the particle size of the composite conductive particles is 10-500μm; for example, 10μm, 50μm, 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm, 500μm, etc.

[0015] A second aspect of the present invention provides a method for preparing the composite conductive material described in the first aspect of the present invention.

[0016] Specifically, the preparation method of the composite conductive material includes the following steps: (1) Mix aniline monomer, dopant and solvent to obtain a mixed solution; mix graphite and nickel to obtain a mixture; (2) The mixture and the mixed solution are mixed, an oxidant is added, and the reaction is carried out to obtain the composite conductive material.

[0017] Specifically, graphite and nickel are introduced during the synthesis of polyaniline-doped particles (polyaniline-dodecylbenzenesulfonic acid). The oxidant initiates an oxidative polymerization reaction to form polyaniline deposited on the surface of graphite and nickel, resulting in a composite conductive material with a core-shell structure. The core-shell structure endows the material with excellent electrical conductivity and superior corrosion resistance.

[0018] Preferably, in step (1), the dopant includes dodecylbenzenesulfonic acid.

[0019] Specifically, a stable reactive emulsion system is constructed using dodecylbenzenesulfonic acid (DBSA) as both an emulsifier and a dopant. Graphite powder and nickel powder are uniformly dispersed in the emulsion system as a mixed core. Aniline monomers are then subjected to in-situ oxidative polymerization on the surface of the mixed core to generate a uniform and dense polyaniline coating shell, ensuring the uniformity and stability of the shell.

[0020] Preferably, the molar ratio of the aniline monomer to the dopant is 1:(0.8-1.5); for example, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, etc.

[0021] Preferably, in step (1), the solvent includes water.

[0022] Preferably, the weight ratio of graphite to nickel is (3-9):1; for example, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, etc.

[0023] Specifically, the graphite exists in the form of graphite powder, and the nickel exists in the form of nickel powder.

[0024] Preferably, the weight ratio of the total weight of graphite and nickel to the weight of aniline monomer is (1.5-3.0):1; for example, 1.5:1, 2:1, 2.5:1, 3:1, etc.

[0025] Preferably, both the graphite and nickel are pretreated, and then the pretreated graphite and pretreated nickel are mixed to obtain the mixture.

[0026] Preferably, the pretreatment process of the graphite is as follows: mixing graphite and solvent, and then ultrasonically dispersing.

[0027] Preferably, the pretreatment process for the nickel is as follows: mixing nickel and solvent, and then ultrasonically dispersing.

[0028] Specifically, pretreatment can effectively remove impurities from the particle surface and break up agglomerates, ensuring the purity of the core material and improving its surface activity, thereby providing an ideal substrate for subsequent coating reactions.

[0029] Preferably, the ultrasonic dispersion process further includes a drying process.

[0030] Preferably, in the pretreatment of graphite and nickel, the solvent includes anhydrous ethanol.

[0031] Preferably, in step (2), after the mixture and the mixed solution are mixed, the pH of the system is adjusted and maintained at 1-2 to precisely control the polymerization reaction conditions.

[0032] Preferably, dilute hydrochloric acid or dilute ammonia is used to adjust and maintain the pH of the system.

[0033] Preferably, in step (2), the oxidant is added under ice-water bath conditions.

[0034] Preferably, the temperature of the ice-water bath is 0-5℃; for example, 0℃, 1℃, 2℃, 3℃, 4℃, 5℃, etc.

[0035] Preferably, the oxidant includes at least one of ammonium persulfate and ferric chloride.

[0036] Preferably, the molar ratio of the oxidant to the aniline monomer is (1.1-1.3):1; for example, 1.1:1, 1.2:1, 1.3:1, etc.

[0037] Preferably, the reaction temperature is 0-5℃; for example, 0℃, 1℃, 2℃, 3℃, 4℃, 5℃, etc.

[0038] Preferably, the reaction time is 2-4 hours; for example, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, etc.

[0039] Preferably, the reaction further includes centrifugation, washing, and drying processes.

[0040] Preferably, the drying is vacuum drying, the vacuum drying temperature is 55-65℃, and the drying time is 46-50h; for example, the vacuum drying temperature is 55℃, 60℃, 65℃, etc., and the drying time is 46h, 47h, 48h, 49h, 50h, etc.; to prevent the particles from agglomerating or oxidizing at high temperatures, thereby obtaining a conductive powder with stable performance.

[0041] A third aspect of the present invention provides a coating.

[0042] Specifically, the coating includes the composite conductive material described in the first aspect of this invention.

[0043] Preferably, the coating comprises component A and component B; component A comprises a resin matrix and the composite conductive material described in the first aspect of the present invention; and component B comprises a curing agent.

[0044] Preferably, by weight, component A comprises 30-60 parts of resin matrix and 5-20 parts of composite conductive material.

[0045] Preferably, component A further includes a solvent and an additive.

[0046] Preferably, by weight, component A comprises 30-60 parts of resin matrix, 5-20 parts of composite conductive material, 20-40 parts of solvent, and 0.7-5 parts of additives.

[0047] Preferably, the additive includes at least one of an adhesion promoter, a defoamer, and a leveling agent; more preferably, the additive includes an adhesion promoter, a defoamer, and a leveling agent.

[0048] Preferably, by weight, component A comprises 30-60 parts of resin matrix, 5-20 parts of composite conductive material, 20-40 parts of solvent, 0.5-3 parts of adhesion promoter, 0.1-1 parts of defoamer and 0.1-1 parts of leveling agent.

[0049] Preferably, the resin matrix includes at least one of epoxy resin and polyurethane resin to enhance the adhesion and durability of the coating.

[0050] Preferably, the solvent comprises a mixture of N-methylpyrrolidone (NMP), ethanol, and water. The choice of solvent helps to improve the application performance of the coating and the uniformity of the coating formation.

[0051] Preferably, in the solvent, the mass ratio of N-methylpyrrolidone, ethanol and water is (70-80):(15-20):A, where A is greater than 0 and less than 1.

[0052] Preferably, the adhesion promoter includes at least one of 3-aminopropyltriethoxysilane (APTES) and γ-glycidoxypropyltrimethoxysilane (GPTMS); the adhesion promoter can enhance the bonding strength between the coating and the substrate surface.

[0053] Preferably, the defoamer includes an organosilicon defoamer, which can reduce the generation of bubbles during coating application.

[0054] Preferably, the leveling agent includes at least one of acrylate leveling agents and silicone leveling agents to improve the smoothness and surface finish of the coating.

[0055] Preferably, the curing agent comprises a modified polyamide resin.

[0056] Preferably, the weight ratio of component A to component B is (1.5-2.5):1; for example, 1.5:1, 2:1, 2.5:1, etc.

[0057] Preferably, the method for preparing the coating includes the following steps: The raw material components of component A are mixed to obtain component A; The coating is composed of components A and B.

[0058] A fourth aspect of the present invention provides the application of the coating described in the third aspect of the present invention in the corrosion protection of grounding grids.

[0059] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows: (1) This invention uses graphite and nickel as the core and polyaniline and dopants as the shell to form a core-shell structure composite conductive material. Graphite, due to its layered structure, can provide an efficient electronic conduction path, while nickel, due to its excellent conductivity and corrosion resistance, complements the conductivity of the coating. Polyaniline, as the conductive shell, not only provides excellent conductivity but also has electrochemical activity, providing corrosion resistance to the coating. Through the synergistic effect of graphite, nickel, and polyaniline, the coating possesses good conductivity, conductivity stability, resistance to high current impact, and corrosion resistance.

[0060] (2) The graphite / nickel powder core-shell structure is prepared by oxidative polymerization, which is one of the core innovations of this invention. The polyaniline shell is enhanced in electrochemical properties and flexibility through DBSA doping, forming a uniform and continuous protective shell. This structural design optimizes the interfacial bonding between the core structure filler and the resin, improving the dispersion uniformity and corrosion resistance of the coating. In addition, the micron-sized core-shell particles overcome the construction problems caused by particle agglomeration in traditional coatings, giving the coating better film-forming properties and workability.

[0061] (3) The resin matrix in the coating of the present invention ensures that the coating has good adhesion and durability; the solvent system optimizes the coating's workability; and the additives comprehensively improve the coating's application performance and surface quality. The optimal coating effect can be achieved by compounding each raw material component in a reasonable amount.

[0062] (4) This invention employs a chemical oxidative polymerization method, which allows graphite powder and nickel powder to be uniformly coated within a polyaniline shell. By precisely controlling reaction conditions such as temperature, pH value, and reaction time, the uniform distribution and stability of the particles are ensured. This process is both highly efficient and repeatable, making it suitable for large-scale production.

[0063] (5) The coating of this invention can provide long-term protection in the complex environment of the grounding grid. The coating has strong corrosion resistance, excellent conductivity, conductivity stability and resistance to high current impact, ensuring the safe and stable operation of power facilities. Experiments have shown that the coating significantly reduces the corrosion rate of the grounding grid and improves the current dissipation performance, which has a positive impact on the overall efficiency of the grounding system. Attached Figure Description

[0064] Figure 1 This is a schematic diagram of the preparation process of the composite conductive material in Example 1 of the present invention; Figure 2 This is a schematic diagram illustrating the principle of the coating exhibiting good corrosion resistance in Example 1 of the present invention. Figure 3 This is a scanning electron microscope image of the composite conductive material of Embodiment 1 of the present invention; Figure 4 This is a scanning electron microscope image of the coating obtained by the coating in Example 1 of the present invention; Figure 5 The image shows a scanning electron microscope (SEM) image of the coating obtained by the coating in Example 1 of this invention after five high-current shocks. Figure 6 The graph shows the corrosion resistance test results of the coatings in Application Example 1 and Comparative Application Example 1 of the present invention. Detailed Implementation

[0065] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0066] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0067] Example 1 The ultimate goal of this embodiment is to provide a core-shell structured composite particle that combines high conductivity, conductive stability, resistance to high current impact, and corrosion resistance, providing a core functional filler for the formulation of subsequent conductive coatings.

[0068] Specifically, this embodiment provides a composite conductive material having a core-shell structure. The core of the core-shell structure is composed of graphite and nickel, and the shell of the core-shell structure is composed of polyaniline and dodecylbenzenesulfonic acid.

[0069] This embodiment also provides a method for preparing the above-mentioned composite conductive material, the steps of which are as follows: (1) Graphite powder and nickel powder were ultrasonically dispersed in anhydrous ethanol. The ultrasonic dispersion power was 250W and the time was 45min to effectively remove impurities on the particle surface and break up agglomerates. Then, they were vacuum dried at 60℃ for 12h to obtain pretreated graphite powder and pretreated nickel powder. 9.3g of aniline monomer and 32.7g of dodecylbenzenesulfonic acid (DBSA) were thoroughly mixed and stirred in 110mL of deionized water to form a homogeneous and stable reaction emulsion; (2) In order to achieve uniform coating of the core material, 16.0g of pretreated graphite powder and 4.0g of pretreated nickel powder (both with a particle size of 2μm) were added to the reaction emulsion obtained in step (1) and ultrasonically treated again (power 10W, 15min) to ensure that it was fully dispersed. In order to accurately control the polymerization reaction conditions, the initial pH value of the mixed system was adjusted and maintained at 1.0-2.0 using dilute hydrochloric acid or dilute ammonia. The entire system was placed in a low-temperature ice-water bath (3℃), and under continuous mechanical stirring (400rpm), 20wt% ammonium persulfate (APS) oxidant aqueous solution (the molar ratio of APS to aniline monomer is 1.2:1) was slowly added dropwise over 1h using a constant flow pump. After the addition was completed, the reaction was continued at this temperature for 3h to ensure complete polymerization and finally form a dense core-shell structure. (3) The product was purified by centrifugation (8000 rpm) three times, followed by washing with deionized water and ethanol. The product was then dried at 60°C for 48 hours under vacuum.

[0070] A schematic diagram of the preparation process of the composite conductive material in Example 1 of this invention is shown below. Figure 1 As shown.

[0071] Comparative Example 1 Comparative Example 1 uses pretreated graphite powder and pretreated nickel powder as composite conductive materials. 16.0g of pretreated graphite powder and 4.0g of pretreated nickel powder are mechanically stirred in a container to make them simply physically mixed evenly, resulting in 20.0g of mixed conductive filler, which is used as composite conductive material without any polymer coating treatment.

[0072] Application Example 1 This application example provides a coating composed of component A and component B in a weight ratio of 2:1; By weight, component A consists of 50 parts of bisphenol A epoxy resin (E-51), 15 parts of the composite conductive material of Example 1, 30 parts of mixed solvent (of which, 22.5 parts of N-methylpyrrolidone, 7.3 parts of ethanol, and 0.2 parts of deionized water), 2 parts of adhesion promoter (KH-550), 0.5 parts of defoamer (BYK-A 530), and 0.5 parts of leveling agent (BYK-333). Component B is modified polyamide resin (Greenlink (Jining) Chemical Technology Co., Ltd., TV8140).

[0073] This embodiment also provides a method for preparing the above-mentioned coating, the steps of which are as follows: The raw material components of component A are dispersed in a high-speed shear disperser at a speed of 2000 rpm for 60 minutes to obtain a uniform and stable paint base, namely component A. Component A and Component B constitute the coating.

[0074] Application Example 1: A schematic diagram illustrating the principle behind the coating's excellent corrosion resistance is shown below. Figure 2 As shown, the epoxy resin matrix and the composite conductive material form a dense coating structure, effectively isolating corrosive media (such as water, oxygen, chloride ions, etc.) from direct contact with the metal substrate, providing the first physical protective barrier. Furthermore, the graphite / nickel composite core provides a stable conductive path; even after long-term immersion in a corrosive environment, the coating maintains low resistivity and good current dissipation capability, ensuring that the grounding grid's discharge function remains unaffected.

[0075] Comparative Application Example 1 The only difference between Comparative Application Example 1 and Application Example 1 is that Comparative Application Example 1 uses the composite conductive material of Comparative Example 1 to replace the core-shell structured composite conductive material of Example 1 in equal amounts. All other components, amounts, and preparation processes are the same as in Application Example 1.

[0076] Performance testing 1. Scanning electron microscopy observation The composite conductive material prepared in Example 1 was observed by scanning electron microscopy, and the results are as follows: Figure 3 As shown.

[0077] Depend on Figure 3 It can be seen that the composite conductive material has a size of 10-500μm and exhibits a vesicle-like encapsulation morphology, which directly confirms that the graphite / nickel powder core is effectively encapsulated by the polyaniline shell.

[0078] 2. Scanning electron microscopy observation of the coating Components A and B from Application Example 1 were mixed at a weight ratio of 2:1 and thoroughly stirred. The mixture was then applied to a sandblasted Q235 steel plate (100mm × 100mm × 3mm) using a scraping method. The coating was cured for 7 days at room temperature (25±2℃) and relative humidity (50±5%), resulting in a coating thickness of 100±10μm. Scanning electron microscopy was then performed, and the results are as follows: Figure 4 As shown.

[0079] Depend on Figure 4 As can be seen, the cured coating surface exhibits a smooth and dense microstructure, and the composite conductive material is uniformly dispersed in the resin matrix without obvious agglomeration, indicating that the coating of the present invention has excellent film-forming properties and application performance.

[0080] 3. High current surge resistance test The high-current impulse resistance test simulates the extreme conditions of a grounding grid when it encounters a lightning strike or short-circuit fault, and examines the structural stability and performance retention of the coating under the influence of instantaneous high current impulse.

[0081] (1) The coating prepared in Application Example 1 was uniformly coated onto a sandblasted Q235 steel plate (size: 100mm×100mm×3mm) using the scraping method. The dry film thickness was controlled at 100±10μm by controlling the scraper gap. After coating, the sample was cured at room temperature for 7 days for later use. In order to realistically simulate the destructive effect of lightning, a generator capable of generating a standard 8 / 20 microsecond lightning impulse waveform was selected for testing. The test was conducted in a shielded laboratory with a temperature of 25±2℃ and a relative humidity of 50±5%. (2) Apply current shock to the two diagonal ends of the sample to force the current to flow through the entire coating surface; set the peak value of the shock current to 20kA, perform multiple shocks, and measure the resistance value of the coating before and after the shock and calculate its rate of change.

[0082] After five high-current impacts, the coating morphology was observed using scanning electron microscopy (SEM). The SEM images are shown below. Figure 5 As shown. By Figure 5 It can be seen that the surface morphology of the coating did not change significantly after being subjected to a large current impact. It remained dense and smooth, and no traces of microcracks, ablation pits, or melting and agglomeration of composite conductive material particles caused by the current impact were found.

[0083] The coated sample was placed on a surface resistance meter and measured using the four-probe method. During the test, four equally spaced probes (10 mm apart) were vertically pressed onto the coating surface, and a constant current of 10 mA was applied. The current was injected through the two outer probes, and the voltage drop was measured through the two inner probes. The average surface resistance value before impact was 0.56 Ω. After five high-current impacts, the average surface resistance value was measured to be 0.61 Ω, and the calculated resistance change rate was 8.92%.

[0084] The calculation formula is: (average surface resistance value after impact - average surface resistance value before impact) / average surface resistance value before impact × 100%.

[0085] It is evident that the coating of this invention exhibits excellent resistance to high current impact.

[0086] 4. Volume resistivity test To accurately determine the conductivity of the coating, it is quantified as the intrinsic property of the material, namely volume resistivity, so as to scientifically evaluate its conductivity level and provide a basis for formula optimization.

[0087] (1) The coating prepared in Application Example 1 was uniformly coated onto a clean insulating glass substrate (size: 75mm×25mm×1mm) by using the scraper method. The dry film thickness was controlled at 50±5μm by controlling the scraper gap. After coating, the sample was cured at room temperature for 7 days before use. A high-precision four-probe method was used for testing. The entire measurement process was conducted under constant temperature and humidity conditions (25℃, 50%RH). Measurements were taken at five different locations around the center and perimeter of the sample. At each location, a known stable current (10mA) was applied through the outer probe, and the voltage difference between the inner probes was precisely measured. The initial average volume resistivity of the coating was measured to be 5.23 × 10⁻⁶. -3 Ω·cm, this value will be used as the benchmark value for high and low temperature cycling tests; (2) The sample after step (1) was placed in a high and low temperature alternating damp heat test chamber for temperature control cycling test; the cycling conditions were set as follows: cooling from 25℃ to -10℃ and holding for 1h, then heating to +85℃ and holding for 1h, which is one cycle, and a total of 50 cycles were performed; after completing 50 cycles, the sample was allowed to stand at 25℃ and 50%RH for 2h to recover, and its volume resistivity was measured again using the same method. The average volume resistivity after the cycle was measured to be 5.31×10 -3 Ω·cm.

[0088] According to the formula: Volume resistivity change rate = (Average volume resistivity after cycling - Initial average volume resistivity) / Initial average volume resistivity × 100%, the volume resistivity change rate of the coating after 50 high and low temperature cycles is calculated to be 1.53%, which is less than 2%. This shows that after repeated and drastic temperature changes, the conductive network constructed by the core-shell structure particles inside the coating remains highly stable and exhibits good conductivity.

[0089] For the coating prepared in Comparative Application Example 1, the same test method as described above was used, and the initial average volume resistivity was measured to be 8.76 × 10⁻⁶. -3 The average volume resistivity was measured to be 1.24 × 10⁻⁶ Ω·cm after 50 high and low temperature cycles. -2 The calculated volume resistivity change rate of the coating was 41.6% (Ω·cm), which is much higher than that of Application Example 1. This indicates that under temperature cycling, the contact conductive network between particles in the physically mixed filler of Comparative Example 1 is prone to breakage and recombination, resulting in poor conductivity stability.

[0090] 5. Corrosion resistance and electrical conductivity stability tests The electrical conductivity stability of the coating prepared by the present invention under long-term corrosion conditions was evaluated by simulating high-salinity corrosive environments such as marine or industrial environments.

[0091] (1) To conduct comparative testing, two coating samples were prepared. The coatings prepared in Application Example 1 and Comparative Application Example 1 were uniformly coated on Q235 steel plates (100mm×100mm×3mm) of the same specifications after sandblasting using the scraping method. The dry film thickness of both samples was controlled at 100±10μm and tested after curing at room temperature for 7 days. (2) The two types of cured samples were completely immersed in a 3.5wt% sodium chloride solution. The entire immersion process was carried out in a constant temperature environment of 25±1℃. The samples were taken out at different time points during the immersion process, rinsed with deionized water and dried. The volume resistivity of the coating was measured by the four-probe method.

[0092] The curve showing the change in volume resistivity of the coating over time, i.e., the corrosion resistance test results, is as follows: Figure 6 As shown.

[0093] from Figure 6As can be seen, the coating prepared using the core-shell structured composite conductive material of this invention maintained an extremely low volume resistivity throughout the 87-day salt water immersion process, without significant increase, demonstrating excellent conductive stability and good corrosion resistance. In contrast, the coating prepared using physically blended fillers showed a significant increase in volume resistivity with prolonged immersion time. This indicates that the core-shell structure proposed in this invention is key to achieving long-term conductive stability of the coating under corrosive environments.

[0094] In summary, this invention provides a core-shell structured composite conductive material using graphite and nickel as the core and polyaniline and dopants as the shell. Through the synergistic effect of graphite, nickel, and polyaniline, the coating can provide long-term protection in the complex environment of the grounding grid. The coating has strong corrosion resistance, excellent conductivity, conductivity stability, and resistance to high current surges, ensuring the safe and stable operation of power facilities.

[0095] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A composite conductive material, characterized in that, The composite conductive material has a core-shell structure; The core of the core-shell structure is composed of graphite and nickel; The shell of the core-shell structure comprises polyaniline and dopants; The dopant includes dodecylbenzenesulfonic acid.

2. The composite conductive material according to claim 1, characterized in that, The graphite has a particle size of 1-10 μm; And / or, the nickel has a particle size of 1-5 μm; And / or, the weight ratio of graphite to nickel is (3-9):

1.

3. The composite conductive material according to claim 1, characterized in that, The particle size of the composite conductive material is 10-500 μm.

4. The method for preparing the composite conductive material according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Mix aniline monomer, dopant and solvent to obtain a mixed solution; mix graphite and nickel to obtain a mixture; (2) The mixture and the mixed solution are mixed, an oxidant is added, and the reaction is carried out to obtain the composite conductive material.

5. The preparation method according to claim 4, characterized in that, In step (1), the molar ratio of the aniline monomer to the dopant is 1:(0.8-1.5). And / or, both the graphite and nickel are pretreated first, and then the pretreated graphite and pretreated nickel are mixed to obtain the mixture.

6. The preparation method according to claim 5, characterized in that, The total weight ratio of graphite and nickel to aniline monomer is (1.5-3.0):1; And / or, the pretreatment process of the graphite is as follows: mixing graphite and solvent, and then ultrasonically dispersing; And / or, the pretreatment process for the nickel is as follows: mixing nickel and solvent, and then ultrasonically dispersing.

7. The preparation method according to claim 4, characterized in that, In step (2), the molar ratio of the oxidant to the aniline monomer is (1.1-1.3):1; and / or, the oxidant includes at least one of ammonium persulfate and ferric chloride; And / or, the temperature of the reaction is 0-5°C; And / or, the reaction time is 2-4 hours.

8. A coating, characterized in that, The coating comprises the composite conductive material as described in any one of claims 1-3.

9. The coating according to claim 8, characterized in that, The coating comprises component A and component B; component A comprises a resin matrix and the composite conductive material according to any one of claims 1-3; component B comprises a curing agent.

10. The application of the coating according to any one of claims 8-9 in the corrosion protection of grounding grids.

Images