Grounding resistance reduction material and method for preparing the same

Abstract

The application relates to a grounding resistance reduction material and a preparation method thereof, and relates to the technical field of grounding materials. The composition and mass fraction of the grounding resistance reduction material include: 86-114 parts of conductive material, 1-15 parts of conductive filler, wherein the conductive material is a flexible high-molecular matrix and a three-dimensional interconnected conductive framework which are double-crosslinked by boric acid-glutaraldehyde; the preparation method comprises the following steps: mixing pre-dispersed graphene oxide and a carbon nanotube dispersion liquid, adding a double-crosslinking agent to obtain a slurry-like conductive material, and then mixing the conductive material with the conductive filler, defoaming and segmental curing; the application forms an interface barrier through the synergistic effect of the double-crosslinking structure and the three-dimensional conductive framework, inhibits the penetration of water vapor and corrosive ions, guarantees the long-term stability of the grounding resistance, and can be used for working grounding, protection grounding and lightning protection grounding of a power system.

Description

Technical Field

[0001] This invention relates to the field of grounding materials technology, and in particular to a grounding resistance-reducing material and its preparation method. Background Technology

[0002] Grounding resistance reduction materials are the core functional carriers of power system grounding grids. Their core functions are reflected in three dimensions: first, by expanding the effective contact area of ​​the grounding electrode, the coupling efficiency between the grounding system and the soil is improved; second, the resistivity of the surrounding soil is reduced to ensure that the grounding resistance meets the system operation requirements; and third, the penetration of corrosive media is blocked, achieving the dual goals of long-term stable grounding resistance and protecting the grounding electrode from corrosion, ultimately ensuring the long-term reliability of the power system's working grounding, protective grounding, and lightning protection grounding.

[0003] As power systems expand into extreme environments, the performance requirements for grounding resistance reduction materials are further upgraded. For example, the soil in the highly corrosive areas of southeastern coastal regions has high salt content and high humidity, and the concentration of corrosive ions is significantly higher than in ordinary areas. In such environments, traditional grounding resistance reduction materials are gradually revealing their core weakness of insufficient long-term corrosion resistance: the anti-corrosion components of traditional materials have weak bonding force with the matrix, making it difficult to resist erosion in extreme environments. Once electrochemical corrosion occurs in the grounding electrode, it will lead to a reduction in the cross-sectional area of ​​the grounding electrode and a sharp increase in contact resistance. In severe cases, it can cause the grounding grid to break, resulting in power system protection failure, equipment damage, and even threats to personal safety.

[0004] To address the shortcomings of traditional materials, Chinese invention patent application CN112688093A, published on April 20, 2021, proposes a graphene-modified grounding resistance-reducing module and its processing method. This technology uses sodium-based bentonite as the matrix, and the raw material composition includes sodium-based bentonite, dispersant, graphene, conductive particles, sodium molybdate, sodium sulfate, calcined gypsum, zinc powder, and steel fiber. The processing steps include raw material weighing, preparation of graphene dispersion, preparation of molding slurry, preparation of zinc powder dispersion, and preparation of the resistance-reducing module. This invention aims to improve the resistance reduction, stability, and corrosion resistance of the material through graphene modification, thereby extending the service life of the grounding resistance-reducing module.

[0005] However, in practical applications, the inventors discovered significant flaws in the anti-corrosion solution of this patented technology: First, the zinc powder forms a coating through physical adhesion, resulting in weak bonding with the substrate. After long-term burial, it is prone to peeling off due to soil friction and material deformation. The exposed micropores of sodium-based bentonite after peeling off become channels for corrosive ions to penetrate. Second, sodium molybdate is a water-soluble corrosion inhibitor that is easily lost with water under the leaching effect of rainwater, leading to the formation of anti-corrosion voids inside the material. These flaws mean that the graphene-modified module still cannot meet the long-term anti-corrosion requirements under extreme environments, making it difficult to ensure the long-term stable operation of the grounding grid. Summary of the Invention

[0006] To address the problem of insufficient corrosion resistance and long-term effectiveness of existing grounding resistance reduction materials in extreme environments, this invention provides a grounding resistance reduction material and its preparation method.

[0007] In a first aspect, the present invention provides a grounding resistance-reducing material, which adopts the following technical solution:

[0008] A grounding resistance reducing material, comprising the following components and mass fractions: 86-114 parts of conductive material and 1-15 parts of conductive filler.

[0009] The conductive material is a flexible polymer matrix and a three-dimensional interconnected conductive framework that are double-crosslinked by boric acid and glutaraldehyde, and the mass ratio of the flexible polymer matrix: the three-dimensional interconnected conductive framework: the boric acid-glutaraldehyde double crosslinking agent in the conductive material is 85-99: 10-15: 0.2-0.6.

[0010] The flexible polymer matrix is ​​a blend of one or two of polyvinyl alcohol and sodium polyacrylate;

[0011] The three-dimensional interconnected conductive framework includes two-dimensional graphene oxide sheets as a conductive network and one-dimensional carbon nanotubes as conductive pathways. The carbon nanotubes bridge different graphene oxide sheets, and the mass ratio of carbon nanotubes to graphene oxide is 1:(1-4). The aspect ratio of the carbon nanotubes is ≥500. The number of graphene oxide layers is 1-5, and the average sheet diameter is 2-15 μm.

[0012] The conductive filler is a blend of one or two of carbon black or metal powder.

[0013] The mass ratio of boric acid to glutaraldehyde in the boric acid-glutaraldehyde dual crosslinking agent is 0.1-0.5:0.1-0.3.

[0014] By adopting the above technical solution, a three-dimensional interconnected conductive framework formed by one-dimensional carbon nanotubes and two-dimensional graphene oxide sheets is embedded in the matrix to form a continuous and dense three-dimensional protective network. With the help of the large lateral coverage of graphene oxide and the longitudinal penetration support of carbon nanotubes, the penetration of corrosive media such as water vapor and chloride ions is blocked. The chemical inertness of the flexible polymer matrix composed of polyvinyl alcohol and sodium polyacrylate is utilized to resist soil microbial degradation and corrosive ion erosion. At the same time, its flexibility can adapt to the deformation caused by soil settlement and temperature changes, avoiding material cracking or framework breakage, providing a stable carrier for the anti-corrosion barrier, and further ensuring the integrity of the anti-corrosion structure.

[0015] By employing a boric acid-glutaraldehyde double crosslinking method, boric acid forms reversible diol crosslinking bonds with the hydroxyl groups of the polymer matrix, while glutaraldehyde forms irreversible crosslinking bonds with the amino groups of the polymer matrix. This chemically bonds the three-dimensional interconnected conductive framework with the flexible polymer matrix, allowing the three-dimensional interconnected conductive framework to be stably embedded in the matrix and avoiding the problem of easy detachment caused by traditional physical adhesion. At the same time, the surface of graphene oxide is rich in hydroxyl and carboxyl groups, which can undergo borate esterification reaction with boric acid to form stable BO covalent bonds.

[0016] Carbon black or metal powders, as conductive fillers, fill the micropores of the three-dimensional framework, further reducing the resistance of the conductive pathway. In particular, when metal powders are combined with carbon-based frameworks, they can reduce the interfacial barrier for electron transport and form a strong conductive network with the three-dimensional framework, thereby improving the conductive stability of the material under different stresses.

[0017] In summary, this grounding resistance reduction material, through precise design of its structure, composition, and parameters, forms an interface barrier effect to inhibit the penetration of water vapor and corrosive ions. It can adapt to extreme environments such as the highly corrosive areas of the southeast coast, and while ensuring long-term stability of grounding resistance, it can also achieve full life-cycle corrosion protection for the grounding body. This effectively avoids risks such as grounding grid breakage and power system failure caused by grounding body corrosion, and provides key support for the reliability of power system working grounding, protective grounding, and lightning protection grounding.

[0018] Optionally, the carbon nanotubes are carbon nanotubes modified with carboxyl and amino groups.

[0019] By adopting the above technical solution, a large number of carboxyl active sites are introduced on the surface of carbon nanotubes, breaking the inert structure of the original carbon nanotube surface. The introduced amino groups can form hydrogen bonds with the hydroxyl groups of polyvinyl alcohol or sodium polyacrylate. At the same time, the bifunctional groups and the active groups of the boric acid-glutaraldehyde double crosslinking agent form a synergistic effect, enabling the three-dimensional framework of carbon nanotubes and graphene to build multiple interfaces with the polymer matrix, reducing the micropores at the interface, and thus significantly improving the tightness and stability of the interface bonding. This effectively inhibits the peeling of the conductive framework from the matrix under environmental stress, taking into account both conductivity continuity and environmental adaptability.

[0020] Optionally, the grounding resistance reducing material further includes 2 to 6 parts of a toughening agent, wherein the toughening agent is one of polyvinylpyrrolidone, polyethylene glycol, and hydroxypropyl methylcellulose.

[0021] By adopting the above technical solution, the groups on the molecular chain are inserted into the double cross-linked network formed by boric acid and glutaraldehyde, and the steric hindrance effect reduces the possible excessively dense cross-linking distance, thereby removing the restriction on the free movement of polyvinyl alcohol or sodium polyacrylate polymer chains.

[0022] Optionally, the grounding resistance reducing material further includes 0.5 to 5 parts of an ion exchange component.

[0023] By adopting the above technical solution, the ion exchange component can exchange with positive and negative ions in the soil, continuously releasing conductive ions into the surrounding soil, thus solving the problem of unstable drag reduction effect caused by fluctuations in soil ion concentration. Furthermore, the ion exchange component can adsorb corrosive ions, such as Cl-. - SO4 2- This reduces the corrosion of metal grounding bodies by harmful ions, while preventing interference ions from combining with conductive components, ensuring the smooth conduction path of the material itself, and ultimately achieving the goal of long-term resistance reduction performance and broad environmental adaptability of the grounding system.

[0024] Secondly, the present invention provides a method for preparing a grounding resistance-reducing material, which adopts the following technical solution:

[0025] A method for preparing a grounding resistance reducing material includes the following steps:

[0026] Prepare a 1-10 wt% slurry conductive material, mix the prepared slurry conductive material with conductive filler, and then stir and degas under vacuum to obtain a uniform, bubble-free mixed slurry with a viscosity of 1.5-6 Pa·s at 25°C; shape the mixed slurry into a film or the desired shape; and perform a segmented curing process on the shaped material, including a pre-setting stage and a final setting stage, wherein the temperature and humidity of the pre-setting stage are higher than those of the final setting stage.

[0027] By adopting the above technical solution, the three-dimensional conductive network constructed by stirring and vacuum degassing reduces the resistance to electron transmission. Its continuous and dense structure can also block the penetration channels of corrosive media such as moisture and oxygen. The vacuum environment eliminates air bubbles inside the slurry, avoiding local corrosion caused by ion aggregation at the air bubble locations. At the same time, the slurry state with a viscosity of 1.5 to 6 Pa·s can ensure the uniformity during molding and prevent corrosion weak points caused by uneven thickness.

[0028] The temperature and humidity during the pre-setting stage are higher than those during the final setting stage, which avoids microcracks caused by internal stress in the material, improves the density of the structure, effectively isolates corrosive media from contact with the grounding body, and greatly enhances the material's corrosion resistance.

[0029] Optionally, the method for preparing the slurry-like conductive material includes the following steps:

[0030] Pre-dispersion of graphene oxide: Graphene oxide powder is added to an aqueous solution of polyvinyl alcohol or sodium polyacrylate with a pH of 7.0 to 8.0, and then subjected to shear-cavitation treatment to obtain a graphene oxide dispersion.

[0031] Carbon nanotube pre-dispersion: Carbon nanotube powder is added to an aqueous solution of polyvinyl alcohol or sodium polyacrylate with a pH of 8.3 to 8.8, and then subjected to ultrasonic treatment to obtain a carbon nanotube dispersion.

[0032] Convergence crosslinking: The graphene oxide dispersion and the carbon nanotube dispersion are mixed, the boric acid-glutaraldehyde dual crosslinking agent is added, the pH is adjusted to 7.5-8.2, and the mixture is stirred to form a crosslinked slurry conductive material.

[0033] By adopting the above technical solution, the pre-dispersion process of graphene oxide and carbon nanotubes can not only achieve efficient dispersion of conductive components, but also reduce the risk of corrosion of subsequent material structures by acidic or strongly alkaline environments. Shear-cavitation treatment and ultrasonic treatment break up graphene oxide agglomerates and peel off carbon nanotube bundles, respectively. The resulting uniform dispersion system can avoid galvanic corrosion caused by local enrichment of conductive components, laying the foundation for the corrosion resistance of the material.

[0034] During the confluence crosslinking stage, the composite crosslinking structure formed by boric acid and glutaraldehyde can enhance the stability of polymer molecular chains and reduce the damage to molecular chains caused by corrosive ions in the environment.

[0035] In summary, by addressing the issue of conductive component agglomeration, both conductivity efficiency and localized corrosion are ensured; by constructing a dense conductive network through confluence mixing, conductivity and resistance to dielectric penetration are improved; and by optimizing material structure stability through cross-linking, corrosion resistance and durability are enhanced. Consequently, the grounding resistance-reducing material possesses excellent resistance while also exhibiting superior corrosion resistance, enabling it to withstand complex soil corrosion environments for extended periods, thus prolonging the service life of grounding projects and meeting the technical requirements for long-term stable operation.

[0036] Optionally, in the graphene oxide pre-dispersion step, 0.2 to 0.8 wt% of a π-affinity agent is added.

[0037] By adopting the above technical solution, a π-affinity agent is added to the pre-dispersion step of graphene oxide. Through π-π interactions, it forms a stable bond with the surface of graphene oxide. On the one hand, this further optimizes the dispersion effect of graphene oxide, effectively inhibits the formation and growth of graphene oxide agglomerates, and enables graphene oxide to form a more uniform monodisperse or sheet-like dispersion in the system, further reducing the risk of galvanic corrosion caused by local enrichment of graphene oxide. On the other hand, the stable bond between the π-affinity agent and graphene oxide can form a protective film on the surface of graphene oxide. This protective film not only reduces the probability of direct contact between graphene oxide and corrosive media, but also enhances the density of the network structure, further blocking the penetration channels of corrosive media such as moisture and oxygen. At the same time, during the cross-linking and curing stage, the agent can also form a certain interaction with the polymer molecular chain, helping to improve the overall stability of the coating, reducing the possibility of microcracks in the coating due to environmental changes, further improving the corrosion resistance of the grounding resistance reduction material, and extending the service life of the material in complex soil corrosion environments.

[0038] Optionally, in the carbon nanotube pre-dispersion step, after ultrasonic treatment, 0.5 to 1.0 wt% of non-migratory comb-shaped polyether is added to the carbon nanotube dispersion, stirred and allowed to stand, so that a coating layer of 1 to 5 nm is formed on the surface of the carbon nanotubes.

[0039] By adopting the above technical solution, the long-chain structure of non-migratory comb-shaped polyether can be tightly adsorbed onto the surface of carbon nanotubes through intermolecular forces. Its comb-shaped branches can construct a steric hindrance effect in the dispersion system, which not only hinders the aggregation of carbon nanotubes and avoids the generation of interfacial voids due to uneven dispersion, but also reduces the permeation channels of water, corrosive ions, etc.; moreover, the polar groups in its molecular chain can form a strong interaction with the subsequent matrix material, improve the interfacial bonding strength, and further block the migration and diffusion of corrosive media at the interface.

[0040] Optionally, sodium dodecylbenzenesulfonate, comprising 0.05 to 0.1 wt% of the carbon nanotubes, is added to the non-migratory comb-like polyether.

[0041] By adopting the above technical solution, the amphiphilic structure of sodium dodecylbenzenesulfonate can form complementary adsorption with the long-chain structure of comb-like polyether: its hydrophobic chains can associate with the alkyl chains of comb-like polyether or the surface of carbon nanotubes through van der Waals forces, further enhancing the intermolecular binding force, while the hydrophilic sulfonic acid groups can form hydrogen bonds with the polar groups of comb-like polyether, making the adsorption layer structure on the surface of carbon nanotubes more compact and improving the thickness uniformity, effectively filling the micro gaps that may exist in the original adsorption layer; at the same time, sodium dodecylbenzenesulfonate further hinders the aggregation of carbon nanotubes through electrostatic repulsion, avoiding interfacial voids caused by uneven dispersion, and significantly improves the dispersion uniformity of carbon nanotubes in the matrix through the steric hindrance effect with comb-like polyether, reducing the risk of electrochemical corrosion caused by uneven conductivity due to aggregation.

[0042] In addition, sodium dodecylbenzenesulfonate can improve the interfacial compatibility between carbon nanotubes and subsequent matrix materials. Its molecular chains can serve as an intermediate structure connecting the adsorption layer on the surface of carbon nanotubes and the matrix molecules, thereby enhancing the interfacial bonding strength and further blocking the migration and diffusion of corrosive media at the interface.

[0043] In summary, the present invention has at least one of the following beneficial technical effects:

[0044] 1. By employing a flexible polymer matrix with boric acid-glutaraldehyde double cross-linking and a three-dimensional interconnected conductive framework, an interfacial barrier effect is formed to inhibit the penetration of water vapor and corrosive ions. This not only adapts to extreme environments such as the highly corrosive areas of the southeast coast, but also ensures long-term stability of grounding resistance while achieving full life-cycle corrosion protection for the grounding body. This effectively avoids risks such as grounding grid breakage and power system failure caused by grounding body corrosion, providing key support for the reliability of power system working grounding, protective grounding, and lightning protection grounding.

[0045] 2. By introducing a large number of active sites on the surface of carbon nanotubes, multiple interfacial bonds are constructed, reducing the micropores at the interface and thus significantly improving the tightness and stability of the interfacial bonding. This effectively inhibits the peeling of the conductive framework from the matrix under environmental stress, taking into account both conductivity continuity and environmental adaptability. Furthermore, by inserting groups on the toughening agent molecular chain into the double cross-linked network formed by boric acid and glutaraldehyde, the steric hindrance effect reduces the potentially excessively dense cross-linking spacing, thereby relieving the restriction on the free movement of polyvinyl alcohol or sodium polyacrylate polymer chains.

[0046] 3. By using a slurry-like conductive material, the problem of conductive component agglomeration is solved, ensuring both conductivity efficiency and avoiding localized corrosion; by constructing a dense conductive network through confluence mixing, conductivity and resistance to media penetration are improved; and by optimizing the material structure stability through cross-linking, corrosion resistance and durability are enhanced.

[0047] 4. By utilizing the amphiphilic structure of sodium dodecylbenzenesulfonate, complementary adsorption can be formed with the long-chain structure of comb-like polyether, significantly improving the dispersion uniformity of carbon nanotubes in the matrix and reducing the risk of electrochemical corrosion caused by uneven conductivity due to agglomeration; at the same time, sodium dodecylbenzenesulfonate can also improve the interfacial compatibility between carbon nanotubes and subsequent matrix materials, enhance the interfacial bonding strength, and further block the migration and diffusion of corrosive media at the interface. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the corrosion cross-section of the grounding resistance-reducing material in Embodiment 1 of this application;

[0049] Figure 2 This is a schematic diagram of the corrosion cross-section of the grounding resistance-reducing material in Embodiment 7 of this application;

[0050] Figure 3 This is a schematic diagram of the corrosion cross-section of the grounding resistance-reducing material in Comparative Example 3 of this application;

[0051] Figure 4 This is a schematic diagram showing the corrosion time variation of the grounding resistance reduction material in the embodiments of this application. Detailed Implementation

[0052] The present invention will be further described in detail below with reference to the embodiments.

[0053] Unless otherwise specified, the experimental methods used in the embodiments of this application are conventional methods, and the materials used are commercially available unless otherwise specified.

[0054] Example 1: This example discloses a grounding resistance reducing material and its preparation method.

[0055] A grounding resistance reducing material, comprising the following components and mass fractions: 100 parts conductive material and 8 parts conductive filler.

[0056] The mass ratio of each component in the conductive material is: flexible polymer matrix: three-dimensional interconnected conductive framework: boric acid-glutaraldehyde dual crosslinking agent = 92:8:0.4.

[0057] In the three-dimensional interconnected conductive framework, the mass ratio of carbon nanotubes with an aspect ratio of 600 to graphene oxide is 1:2.5. The graphene oxide has 3 layers with an average sheet diameter of 8 μm. The carbon nanotubes bridge the graphene oxide sheets to form a three-dimensional conductive network.

[0058] The conductive filler is a blend of carbon black with a particle size of 20 nm and copper powder with a particle size of 50 μm in a mass ratio of 2:1; in the boric acid-glutaraldehyde dual crosslinking agent, the mass ratio of boric acid to glutaraldehyde is 0.3:0.2.

[0059] In this embodiment, the flexible polymer matrix is ​​a blend of polyvinyl alcohol and sodium polyacrylate in a mass ratio of 3:1. In other embodiments, either polyvinyl alcohol or sodium polyacrylate can be selected. In this embodiment, the conductive filler is a blend of carbon black and copper powder. In other embodiments, either carbon black or copper powder can be selected.

[0060] Its preparation method is as follows:

[0061] Pre-dispersion of graphene oxide: Prepare a 3wt% polyvinyl alcohol-sodium polyacrylate continuous phase polymer aqueous solution, adjust the pH to 7.5, add graphene oxide powder, and perform shear-cavitation treatment to control the specific energy to 200 kJ·L. -1 Instantaneous shear rate 3×10 3 s -1 The temperature is ≤40℃, and the treatment time is 40 min to obtain an aqueous dispersion of graphene oxide.

[0062] Carbon nanotube pre-dispersion: Prepare a 0.35wt% polyvinyl alcohol-sodium polyacrylate continuous phase polymer aqueous solution, adjust the pH to 8.5, add carbon nanotube powder, and sonicate at 400W for 45min to obtain a carbon nanotube dispersion.

[0063] Confluence crosslinking: Graphene oxide dispersion and carbon nanotube dispersion were confluenced in a micro-mixing device at a corresponding powder mass ratio of 1:2.5, with a residence time of 15s. Boric acid-glutaraldehyde dual crosslinking agent was added, and the synergistic mechanism of reversible crosslinking of boric acid-diol and irreversible crosslinking of trace amounts of glutaraldehyde was adopted. The pH was adjusted to 7.8, and the mixture was stirred at 400r / min for 6min to obtain a slurry conductive material.

[0064] In other embodiments, the slurry conductive material can also be directly formulated into a slurry conductive material solution by means of powdered conductive material and solvent.

[0065] Degassing and curing: The prepared slurry-like conductive material and conductive filler were mixed according to the mass ratio, stirred for 20 min at 30℃ and 1000 r / min, and then transferred to a device with a vacuum degree of -0.08 MPa for degassing for 20 min to obtain a uniform, bubble-free mixed slurry with a viscosity of 4 Pa·s at 25℃. The mixed slurry was coated into a 2±1 mm film, pre-cured for 2 h at 40±2℃ and 50% relative humidity, and then finally cured for 4 h at 25±2℃ and 40% relative humidity to obtain the grounding resistance reducing material. The prepared grounding resistance reducing material was observed by scanning electron microscopy, such as... Figure 1 As shown, the dispersion is good, and no obvious clumping is observed.

[0066] The tests mainly examine the volume resistivity, neutral salt spray corrosion resistance, chloride ion immersion corrosion resistance, and damp heat stability of the grounding resistance reducing material.

[0067] Volume resistivity (Ω·cm): A key parameter for measuring the internal conductivity of grounding resistance-reducing materials. It directly determines the resistance-reducing performance of the material. The lower the volume resistivity, the higher the material's conductivity, and the easier it is to meet the design requirements for grounding resistance. At the same time, low volume resistivity can ensure that the current is uniformly conducted inside the material, prevent local overheating from causing material aging, and extend the service life of the grounding electrode.

[0068] The specific testing method is as follows: According to GB / T1410-2006 "Test Method for Volume Resistivity and Surface Resistivity of Solid Insulating Materials", the three-electrode method is used to measure the volume resistivity of the grounding resistance reduction material under the conditions of 25℃ and 60%±5% relative humidity. The average value is taken after three parallel measurements.

[0069] Neutral salt spray corrosion performance (%): used to evaluate the corrosion resistance of grounding resistance reducing materials in salt spray environment; grounding body is buried in soil or exposed outdoors for a long time, and is susceptible to corrosion by salt and moisture in the air. If the material has poor salt spray corrosion resistance, the surface will gradually rust and peel off, resulting in a reduction in conductive cross-sectional area and an increase in grounding resistance.

[0070] The specific testing method is as follows: According to GB / T10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test", the material sample is placed in a neutral salt spray environment of 35±2℃ and 5wt% sodium chloride solution and continuously sprayed for 96 hours. The surface corrosion status is observed and the percentage of rusted area is recorded in %, and its salt spray corrosion resistance is evaluated.

[0071] Chloride ion immersion corrosion performance (%): The material's resistance to chloride ion erosion is assessed by simulating a high chloride ion soil environment, and the structural loss caused by chloride ion corrosion is evaluated.

[0072] The specific testing method is as follows: Immerse the grounding resistance reducing material sample in a 0.1 mol / L sodium chloride solution at 25℃. After 30 days, take out the sample and measure the sample mass loss rate. Perform three parallel measurements and take the average value. Evaluate its resistance to chloride ion corrosion based on the mass loss.

[0073] Moisture and heat resistance retention rate (%): This verifies the material's ability to retain its performance under high temperature and high humidity conditions, and assesses whether the material can still maintain stable electrical conductivity in humid climates or soils with high groundwater levels.

[0074] The specific testing method is as follows: a constant damp heat test is conducted according to the test method of GB / T2423.3-2016. The material sample is placed in an environment of 85℃ and relative humidity of 85%±2% for 168 hours. After that, the grounding resistance of the sample is measured again. The average value is taken after three parallel measurements. According to the formula: performance retention rate = grounding resistance after damp heat / grounding resistance before damp heat × 100%. The closer the value is to 100%, the stronger the material's resistance to damp heat.

[0075] Example 2: This example discloses a grounding resistance reducing material and its preparation method.

[0076] In this embodiment, a grounding resistance reducing material comprises, by weight, 86 parts of conductive material and 15 parts of conductive filler.

[0077] Everything else is exactly the same as in Example 1.

[0078] Example 3: This example discloses a grounding resistance reducing material and its preparation method.

[0079] In this embodiment, a grounding resistance reducing material is composed of the following components and mass fractions: 115 parts of conductive material and 1 part of conductive filler.

[0080] Everything else is exactly the same as in Example 1.

[0081] Grounding resistance reducing materials were prepared using the material composition, mass fraction, and preparation method described in Examples 1, 2, and 3, respectively. The key performance indicators of the grounding resistance reducing materials were tested, and the test results are shown in Table 1.

[0082] Table 1:

[0083] Test content Example 1 Example 2 Example 3 Volume resistivity (Ω·cm) 5.1 5.0 5.3 Neutral salt spray corrosion performance (%) 4.2 4.7 4.0 Chloride ion immersion corrosion performance (%) 3.9 4.3 3.7 Retention rate of damp heat resistance (%) 95.0 93.8 94.5

[0084] By comparing Examples 1, 2, and 3, it can be seen that Example 2 has the lowest volume resistivity. This is because volume resistivity depends on the distribution density of the three-dimensional interconnected conductive framework. In Example 2, the ratio of conductive material to conductive filler is more conducive to the formation of a continuous path in the conductive framework, resulting in the lowest resistance to current conduction. However, in Example 3, the slightly poor compatibility between the conductive material and the conductive filler may lead to local discontinuities in the conductive network, resulting in a slightly higher resistivity.

[0085] In terms of neutral salt spray corrosion resistance and chloride ion immersion corrosion resistance, Example 3 is superior to Examples 1 and 2. The core reason is that corrosion resistance depends on the conductive material's adsorption capacity for corrosion ions and the material's density. In Example 3, the conductive material has the highest proportion, and the three-dimensional interconnected conductive framework is more tightly bonded, effectively blocking chloride ions. - Regarding the retention rate of moisture and heat resistance, Example 1 is the best. The reason is that the moisture and heat resistance stability needs to balance the stability of the conductive network and the swelling resistance of the matrix structure.

[0086] Example 4: This example discloses a grounding resistance reducing material and its preparation method.

[0087] In this embodiment, the carbon nanotubes in the three-dimensional interconnected conductive framework are carbon nanotubes modified with carboxyl and amino groups. The modification process involves refluxing the carbon nanotubes in a mixture of nitric acid and sulfuric acid for 4 hours to introduce carboxyl groups, and then reacting them with ethylenediamine at 60°C for 3 hours to introduce amino groups.

[0088] Everything else is exactly the same as in Example 1.

[0089] Example 5: This example discloses a grounding resistance reducing material and its preparation method.

[0090] In this embodiment, the grounding resistance reducing material also includes 4 parts of toughening agent, and the toughening agent used in this embodiment is polyvinylpyrrolidone.

[0091] Everything else is exactly the same as in Example 4.

[0092] Example 6: This example discloses a grounding resistance reducing material and its preparation method.

[0093] In this embodiment, the grounding resistance reducing material also includes 3 parts of ion exchange components. The ion exchange components are one or more of zeolite powder, mesoporous silica, and hydroxyapatite. In this embodiment, hydroxyapatite is selected.

[0094] Everything else is exactly the same as in Example 5.

[0095] Grounding resistance reducing materials were prepared using the material composition, mass fraction, and preparation method described in Examples 4-6, respectively. The key performance indicators of the grounding resistance reducing materials were tested, and the test results are shown in Table 2.

[0096] Table 2:

[0097] Test content Example 4 Example 5 Example 6 Volume resistivity (Ω·cm) 4.8 4.9 5.0 Neutral salt spray corrosion performance (%) 3.7 3.5 3.3 Chloride ion immersion corrosion performance (%) 3.4 3.2 2.9 Retention rate of damp heat resistance (%) 95.2 95.5 95.7

[0098] By comparing Example 4 with Example 1, it can be seen that the carbon nanotubes modified with carboxyl and amino groups in Example 4 have carboxyl groups introduced on their surface. The polarity of the carboxyl groups can enhance the interaction between the carbon nanotubes and graphene oxide and the polymer matrix, reduce the interfacial resistance during electron transport, and enable electrons to conduct more smoothly in the three-dimensional interconnected conductive network, thereby reducing the volume resistivity of the material. The introduction of amino groups on the surface of the modified carbon nanotubes further optimizes the electron transport path. Amino groups can react with other substances containing active groups to form more chemical bonds or stronger interactions between the carbon nanotubes and the surrounding materials, such as forming hydrogen bonds or covalent bonds with certain functional groups in the matrix, providing more conduction channels for electrons and further enhancing the internal conductivity of the material.

[0099] Regarding the stability of damp heat resistance and corrosion resistance, the presence of carboxyl and amino groups enhances the chemical stability of the three-dimensional conductive network. Carboxyl groups can coordinate with metal ions to form stable complexes, which can effectively inhibit the dissolution and diffusion of metal ions and prevent corrosion reactions when the material is in a corrosive environment. Amino groups, through their alkaline properties, can neutralize acidic substances in the environment and reduce the erosion of the material by acidic corrosive media. At the same time, the stronger interaction between the modified carbon nanotubes and the matrix makes the material structure more compact, hindering the penetration of corrosive media, thereby improving the corrosion resistance of the material in corrosive environments such as neutral salt spray and chloride ion immersion.

[0100] Comparing Example 5 with Example 4, it can be seen that the addition of polyvinylpyrrolidone as a toughening agent in Example 5 slightly increased the volume resistivity, indicating that the addition of the toughening agent had little impact on the internal conductivity of the material. The reduced neutral salt spray corrosion performance in Example 5 indicates that the toughening agent improved the corrosion resistance of the material in a salt spray environment, suggesting that the toughening agent improved the microstructure of the material, making it more difficult to be corroded by salt and moisture. The reduced chloride ion immersion corrosion performance reflects the enhanced resistance of the material to chloride ion erosion in a high chloride ion soil environment, indicating that the toughening agent enhanced the stability of the material structure and reduced the damage caused by chloride ions. The slightly improved retention rate of damp heat resistance indicates that the toughening agent enhanced the intermolecular interactions of the material, enabling it to better maintain stability in a humid environment.

[0101] By comparing Example 6 with Example 5, it can be seen that hydroxyapatite enhances corrosion resistance. Without significantly sacrificing conductivity, the hydroxyl groups on the surface of hydroxyapatite form hydrogen bonds with the hydroxyl groups of the polymer matrix, enhancing interfacial bonding and preventing the matrix from peeling off from the conductive framework under corrosive conditions. In addition, after the hydroxyapatite particles are uniformly dispersed in the slurry conductive material, they form a composite barrier with the polyvinyl alcohol-sodium polyacrylate crosslinked matrix. These synergistic effects improve the structural stability of the material in humid and hot environments.

[0102] Example 7: This example discloses a grounding resistance reducing material and its preparation method.

[0103] In this embodiment, the structure and composition of the grounding resistance reduction material are the same as in Example 6. The difference lies in the preparation method of the slurry conductive material. Specifically, in the graphene oxide pre-dispersion step, 0.5 wt% of a π-affinity additive is added, and the graphene oxide powder is added together with the polyvinyl alcohol-sodium polyacrylate aqueous solution for shear-cavitation treatment.

[0104] The π-affinity auxiliaries can be selected from one or a mixture of several naphthyl derivatives, pyrene small molecules, and benzene ring branched polymers. In this embodiment, 1,5-diaminonaphthalene, a naphthyl derivative, is selected.

[0105] Everything else is exactly the same as in Example 6. The prepared grounding resistance-reducing material was observed using a scanning electron microscope, such as... Figure 2 As shown, the dispersion is good, and no obvious clumping is observed.

[0106] Example 8: This example discloses a grounding resistance reducing material and its preparation method.

[0107] In this embodiment, during the carbon nanotube pre-dispersion step, after ultrasonic treatment for 45 minutes, 0.8 wt% of non-migratory comb-shaped polyether was added to the carbon nanotube dispersion, and the mixture was stirred at 400 r / min for 10 minutes, followed by standing for 30 minutes, so that the non-migratory comb-shaped polyether formed a 3 nm thick coating layer on the surface of the carbon nanotubes.

[0108] Everything else is exactly the same as in Example 7.

[0109] Example 9: This example discloses a grounding resistance reducing material and its preparation method.

[0110] In this embodiment, during the carbon nanotube pre-dispersion step, sodium dodecylbenzenesulfonate, accounting for 0.08 wt% of the carbon nanotube mass, is added to the non-migratory comb polyether and added together with the non-migratory comb polyether to the carbon nanotube dispersion.

[0111] Everything else is exactly the same as in Example 8.

[0112] Grounding resistance reducing materials were prepared using the material composition, mass fraction, and preparation method described in Examples 4-6, respectively. The key performance indicators of the grounding resistance reducing materials were tested, and the test results are shown in Table 3.

[0113] Table 3:

[0114] Test content Example 7 Example 8 Example 9 Volume resistivity (Ω·cm) 4.7 4.5 4.4 Neutral salt spray corrosion performance (%) 3.2 3.0 2.8 Chloride ion immersion corrosion performance (%) 3.0 2.7 2.5 Retention rate of damp heat resistance (%) 95.7 96.0 96.3

[0115] Comparing Example 7 with Example 6, it can be seen that Example 7 added 1,5-diaminonaphthalene in the graphene pre-dispersion step. The naphthalene ring structure in its molecule has a π-π conjugation effect with the six-membered ring structure of the graphene oxide sheets, which can effectively inhibit the stacking and aggregation of graphene oxide sheets, making the graphene oxide more uniformly dispersed in the polymer matrix, thereby optimizing the continuity of the three-dimensional interconnected conductive network and reducing the volume resistivity. At the same time, the more uniform graphene oxide dispersion can enhance its synergistic barrier effect with hydroxyapatite, further blocking the penetration of chloride ions in the salt spray, so the proportion of neutral salt spray corrosion area is slightly reduced. The slight increase in the chloride ion immersion mass loss rate is presumably due to the small size of the π-affinity auxiliary agent molecules, which dissolve in trace amounts during long-term immersion, having a slight impact on the local interfacial bonding force, but the overall impact is negligible and does not change the damp heat resistance stability.

[0116] Comparing Example 8 with Example 7, it can be seen that all performance indices of Example 8 are superior to those of Example 7. This is because the long-chain structure of the non-migratory comb-like polyether can be tightly coated onto the surface of carbon nanotubes through van der Waals forces. On the one hand, this allows the carbon nanotubes to be more uniformly interspersed between the graphene oxide sheets, further improving the three-dimensional interconnected conductive network and reducing current conduction resistance, thus reducing the volume resistivity. On the other hand, the coating layer of the comb-like polyether can form a secondary interface barrier, which, together with graphene oxide-hydroxyapatite, blocks the penetration of chloride ions in salt spray and corrosive ions in immersion solution. Therefore, the proportion of neutral salt spray corrosion area and the mass loss rate of chloride ion immersion are significantly reduced. In addition, the coating layer can also enhance the bonding force between carbon nanotubes and polymer matrix, reduce the risk of conductive skeleton detachment under humid and hot conditions, and slightly improve the stability against humid and hot conditions.

[0117] Comparing Example 9 with Example 8, it can be seen that all performance indices in Example 9 are superior to those in Example 8. This is because sodium dodecylbenzenesulfonate, as an anionic surfactant, has hydrophilic groups that can form hydrogen bonds with the ether bonds of non-migratory comb-like polyethers, while its hydrophobic groups adsorb onto the surface of carbon nanotubes through π-π interactions. On the one hand, this further weakens the van der Waals forces between carbon nanotubes, reducing the local resistance to current conduction, thus further decreasing the volume resistivity. On the other hand, the addition of sodium dodecylbenzenesulfonate optimizes the density of the comb-like polyether coating layer, more effectively blocking the penetration of chloride ions in salt spray and corrosive ions in the immersion solution. Therefore, the proportion of neutral salt spray corrosion area and the chloride ion immersion mass loss rate continue to decrease. In addition, the surfactant can also enhance the interfacial bonding force between carbon nanotubes, comb-like polyethers, and the polymer matrix, reducing the risk of peeling between the conductive framework and the matrix under humid and hot conditions, thus slightly improving the stability against humid and hot conditions.

[0118] Comparative Example 1: This comparative example discloses a grounding resistance reducing material and its preparation method.

[0119] In this comparative example, the conductive material in the grounding resistance reduction material is single graphene oxide, replacing the three-dimensional interconnected conductive framework in Example 1. The mass ratio of each component in the conductive material is: flexible polymer matrix: single graphene oxide: boric acid-glutaraldehyde dual crosslinking agent = 92: 8: 0.4.

[0120] When preparing the slurry conductive material, only the graphene oxide pre-dispersion step is performed, without the carbon nanotube pre-dispersion step. The remaining stirring, degassing, and segmented curing processes are the same as in Example 1.

[0121] Everything else is exactly the same as in Example 1.

[0122] Comparative Example 2: This comparative example discloses a grounding resistance reducing material and its preparation method.

[0123] The conductive material in the grounding resistance reduction material is a single carbon nanotube, replacing the three-dimensional interconnected conductive framework in Example 1. The mass ratio of each component in the conductive material is: flexible polymer matrix: single carbon nanotube: boric acid-glutaraldehyde double crosslinking agent = 92: 8: 0.4.

[0124] When preparing the slurry conductive material, only the carbon nanotubes are pre-dispersed, without the graphene oxide pre-dispersion step. The remaining stirring, degassing, and segmented curing processes are the same as in Example 1.

[0125] Everything else is exactly the same as in Example 1.

[0126] Comparative Example 3: This comparative example discloses a grounding resistance reducing material and its preparation method.

[0127] In this comparative example, the composition and mass fraction of the grounding resistance reduction material are the same as in Example 1, but it is only a physically mixed conductive powder. The preparation method of the three-dimensional interconnect skeleton is replaced. Therefore, the pre-dispersion steps of graphene oxide and carbon nanotubes are removed in the preparation process and replaced with direct physical mixing.

[0128] The preparation method of the slurry conductive material is as follows: The physically mixed conductive powder is directly added to a mixed aqueous solution of polyvinyl alcohol and sodium polyacrylate at pH 7.5. No shearing-cavitation or ultrasonic treatment is required. The mixture is stirred at 600 r / min for 10 min. Then, boric acid-glutaraldehyde dual crosslinking agent is added to adjust the pH to 7.8. The mixture is stirred for another 10 min to form a slurry conductive material containing insufficiently dispersed conductive powder.

[0129] Other aspects are the same as in Example 1. The prepared grounding resistance-reducing material was observed using a scanning electron microscope, such as... Figure 3 As shown, the dispersion is poor, and obvious clumping occurs.

[0130] Comparative Example 4: This comparative example discloses a grounding resistance reducing material and its preparation method.

[0131] In this comparative example, the boric acid-glutaraldehyde double crosslinking agent is removed from the composition of the grounding resistance reducing material, that is, no crosslinking agent is added; a grounding resistance reducing material, the composition and mass parts of which include: 100 parts of conductive material and 8 parts of conductive filler, wherein the mass ratio of each component in the conductive material is: flexible polymer matrix: three-dimensional interconnected conductive skeleton = 92: 8.

[0132] In the preparation process of the grounding resistance reduction material, the addition of the double crosslinking agent is removed in the confluence crosslinking step, and the non-crosslinked slurry conductive material is mixed with the conductive filler. Everything else is exactly the same as in Example 1.

[0133] Grounding resistance reducing materials were prepared using the material compositions, mass fractions, and preparation methods described in Comparative Examples 1-4, respectively. The key performance indicators of the grounding resistance reducing materials were then tested, and the test results are shown in Table 4.

[0134] Table 4:

[0135] Test content Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Volume resistivity (Ω·cm) 7.2 8.5 12.3 6.8 Neutral salt spray corrosion performance (%) 23.5 15.4 19.8 25.7 Chloride ion immersion corrosion performance (%) 30.5 38.6 28.6 30.1 Retention rate of damp heat resistance (%) 60.1 65.7 62.8 69.8

[0136] By comparing Comparative Example 1 with Example 1, it can be seen that the volume resistivity of Comparative Example 1 is higher than that of Example 1. Due to the lack of carbon nanotube bridging, the graphene oxide sheets are prone to local stacking, resulting in a discontinuous conductive network. However, the conductivity of graphene oxide itself is still acceptable, so the resistivity does not increase excessively. However, the corrosion resistance and damp heat resistance retention rates of Comparative Example 1 both decrease. This is because the lack of carbon nanotube bridging support between individual graphene oxide sheets makes them prone to stacking and agglomeration. The gaps formed by the stacking become channels for the penetration of corrosive media. In a salt spray environment, chloride ions rapidly penetrate into the material through the gaps, leading to a significant increase in the rust area. When immersed in chloride ions, the lack of carbon nanotube structural support makes the graphene oxide sheets easy to peel off under corrosion, resulting in a sharp increase in material quality loss. In a damp heat environment, the interfacial bonding force between individual graphene oxide and the polymer matrix is ​​weak, and interface separation easily occurs due to damp heat swelling, destroying the continuity of the conductive network and causing a significant decrease in the grounding resistance retention rate. This fully demonstrates the crucial supporting significance of the bridging effect of carbon nanotubes in the three-dimensional interconnected conductive framework.

[0137] By comparing Comparative Example 2 with Example 1, it can be seen that the performance indicators of Comparative Example 2 are all inferior to those of Example 1. It is speculated that single carbon nanotubes, due to the lack of two-dimensional sheet support, are prone to entanglement and aggregation within the material, resulting in uneven distribution of conductive paths, obvious breakage of conductive paths, and increased volume resistivity. In addition, single carbon nanotubes cannot form a continuous interfacial protective layer. In salt spray environment, the voids formed by the entanglement of carbon nanotubes become chloride ion penetration channels, significantly increasing the corrosion area. When immersed in chloride ions, without the barrier effect of graphene oxide sheets, chloride ions react directly with the surface of carbon nanotubes, causing a sharp increase in mass loss. In humid and hot environment, the interfacial bonding area between single carbon nanotubes and the polymer matrix is ​​small, and it is easy to detach the interface due to humid and hot swelling, destroying the continuity of the conductive network. This fully demonstrates the important role of the two-dimensional sheet structure of graphene oxide in the three-dimensional interconnected conductive framework.

[0138] By comparing Comparative Example 3 with Example 1, it can be seen that Comparative Example 3, through physical stirring and mixing alone, cannot break the van der Waals forces between the graphene oxide sheets, causing the conductive powder to agglomerate inside the material, forming a large number of conductive blind areas, and significantly increasing the volume resistivity. The gaps between the agglomerated particles become rapid penetration channels for chloride ions in salt spray and water vapor in humid and hot environments, accelerating corrosion and expanding the corrosion area. At the same time, when immersed in chloride ions, the material mass loss increases dramatically. In humid and hot environments, water vapor enters the interior of the material through the gaps, causing the polymer matrix to swell more rapidly and destroying the integrity of the conductive network.

[0139] In addition, dynamic detection of chloride ion content was performed in Examples 1, 4, 7, and Comparative Example 1 at time points of 20h, 40h, 70h, and 100h; the corrosion time change of the grounding resistance reducing material is illustrated in the schematic diagram. Figure 4 As shown, the chlorine accumulation in the examples within 100 hours was significantly lower than that in Comparative Example 1. Among them, the chloride ion content in Comparative Example 1 increased the fastest among all groups, indicating that its resistance to chloride ion penetration was poor. Secondly, Example 7 had the best anti-permeability performance, followed by Example 4, and Example 1 also had good performance.

[0140] By comparing Comparative Example 4 with Example 1, it can be seen that Comparative Example 4, lacking a crosslinking agent, relies solely on physical entanglement to form a stable three-dimensional structure. This leads to localized agglomeration of the conductive framework during stirring and degassing, and a small number of breaks in the conductive network, resulting in an increase in volume resistivity. The absence of a crosslinked structure results in a large number of micron-sized voids within the material, accelerating corrosion and significantly increasing mass loss. In humid and hot environments, the uncrosslinked polymer chains are prone to swelling, causing the conductive framework to detach from the matrix interface and reducing the grounding resistance retention rate. This fully demonstrates the core role of the boric acid-glutaraldehyde dual crosslinking agent in achieving low resistance, high corrosion resistance, and high humid and hot stability in the material.

[0141] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A grounding resistance reducing material, characterized in that, The composition and mass fractions include: 86-114 parts of conductive material and 1-15 parts of conductive filler; The conductive material is a flexible polymer matrix and a three-dimensional interconnected conductive framework that are double-crosslinked by boric acid and glutaraldehyde, and the mass ratio of the flexible polymer matrix: the three-dimensional interconnected conductive framework: the boric acid-glutaraldehyde double crosslinking agent in the conductive material is 85-99: 10-15: 0.2-0.

6. The flexible polymer matrix is ​​a blend of one or two of polyvinyl alcohol and sodium polyacrylate; The three-dimensional interconnected conductive framework includes two-dimensional graphene oxide sheets as a conductive network and one-dimensional carbon nanotubes as conductive pathways. The carbon nanotubes bridge different graphene oxide sheets, and the mass ratio of carbon nanotubes to graphene oxide is 1:(1-4). The aspect ratio of the carbon nanotubes is ≥500. The number of graphene oxide layers is 1-5, and the average sheet diameter is 2-15 μm. The conductive filler is a blend of one or two of carbon black or metal powder. The mass ratio of boric acid to glutaraldehyde in the boric acid-glutaraldehyde dual crosslinking agent is 0.1–0.5:0.1–0.

3. The preparation method of the grounding resistance reduction material includes the following steps: preparing 1-10 wt% of a slurry conductive material; mixing the prepared slurry conductive material with conductive filler; and performing stirring and vacuum degassing treatment to obtain a uniform, bubble-free mixed slurry with a viscosity of 1.5-6 Pa·s at 25°C; molding the mixed slurry into a film or a desired shape; and performing a segmented curing process on the molded material, including a pre-setting stage and a final setting stage, wherein the temperature and humidity of the pre-setting stage are higher than those of the final setting stage. The preparation method of the slurry conductive material includes the following steps: Pre-dispersion of graphene oxide: Graphene oxide powder is added to an aqueous solution of polyvinyl alcohol or sodium polyacrylate with a pH of 7.0 to 8.0, and then subjected to shear-cavitation treatment to obtain a graphene oxide dispersion. Carbon nanotube pre-dispersion: Carbon nanotube powder is added to an aqueous solution of polyvinyl alcohol or sodium polyacrylate with a pH of 8.3 to 8.8, and then subjected to ultrasonic treatment to obtain a carbon nanotube dispersion. Convergence crosslinking: The graphene oxide dispersion and the carbon nanotube dispersion are mixed, the boric acid-glutaraldehyde dual crosslinking agent is added, the pH is adjusted to 7.5-8.2, and the mixture is stirred to form a crosslinked slurry conductive material.

2. The grounding resistance reducing material according to claim 1, characterized in that, The carbon nanotubes are carbon nanotubes modified with carboxyl and amino groups.

3. The grounding resistance reducing material according to claim 1, characterized in that, It also includes 2 to 6 parts of a toughening agent, wherein the toughening agent is one of polyvinylpyrrolidone, polyethylene glycol, or hydroxypropyl methylcellulose.

4. The grounding resistance reducing material according to claim 1, characterized in that, It also includes 0.5 to 5 parts of ion exchange components.

5. A grounding resistance reducing material according to claim 1, characterized in that, In the graphene oxide pre-dispersion step, 0.2 to 0.8 wt% of a π-affinity agent is also added.

6. A grounding resistance reducing material according to any one of claims 1-5, characterized in that, In the carbon nanotube pre-dispersion step, after ultrasonic treatment, 0.5 to 1.0 wt% of non-migratory comb-shaped polyether is added to the carbon nanotube dispersion, stirred and allowed to stand, so that a coating layer of 1 to 5 nm is formed on the surface of the carbon nanotubes.

7. A grounding resistance reducing material according to claim 6, characterized in that, Sodium dodecylbenzenesulfonate, comprising 0.05–0.1 wt% of the carbon nanotubes, is added to the non-migratory comb-like polyether.

8. The application of the grounding resistance reducing material according to any one of claims 1-7 in a grounding grid system.

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