A carbon nanometer polymer repairing material for repairing a speed reducer shaft and a preparation method and a repairing process thereof

Abstract

The application discloses a carbon nano polymer repairing material for repairing auxiliary of a speed reducer shaft and a preparation method and a repairing process thereof, and belongs to the technical field of high polymer composite materials. In view of the bottleneck that the existing repairing material is sensitive to construction temperature and humidity, the application provides an A / B two-component self-adapting repairing material. The A component comprises epoxy resin, active diluent, two-dimensional heat-conducting filler and thixotropic agent. The B component comprises aromatic polythiol containing dynamic covalent bond, modified dicyandiamide, latent cationic initiator and catalytic promoter. Compared with the prior art, the application has the advantages of strong environmental adaptability, low volume shrinkage, high interfacial bonding strength and on-site quick repairing without disassembly, and significantly improves the reliability and convenience of the speed reducer shaft repairing.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials and mechanical parts remanufacturing technology, specifically relating to a carbon nanotube polymer repair material for auxiliary repair of gearbox shafts, its preparation method, and repair process. Background Technology

[0002] As the core actuator of industrial power transmission, the speed reducer's output shaft, input shaft, and intermediate shaft are prone to uniform wear, fretting wear, pitting and spalling, or scoring on their mating surfaces such as journals, keyways, and shoulders under long-term heavy loads, impacts, variable loads, and potential misalignment conditions. Once these damages exceed the design tolerances, they will directly lead to excessive clearance, increased vibration, and increased oil temperature, ultimately causing equipment shutdown or even shaft breakage.

[0003] Traditional repair techniques for shaft damage have inherent drawbacks: ① Machining after welding: High heat input, easily leading to thermal deformation and decreased fatigue strength of the shaft, and requires large lathes and grinders, with a construction period of 3-7 days; ② Electroplating: Limited coating thickness (usually <0.3mm), mechanical bonding, prone to peeling under heavy loads, and the plating solution is sensitive to temperature; ③ Thermal spraying: Expensive equipment, requiring specialized sandblasting rooms and spraying robots, unsuitable for on-site repair without disassembly; ④ Replacing with a new shaft: Long procurement cycle and high cost, extremely passive for non-standard or imported equipment.

[0004] In recent years, carbon nanotube polymer repair materials based on epoxy resin (commonly known as "metal repair agents") have been widely used in the field of shaft online repair due to their advantages such as room temperature curing, grindability, and ease of construction. The principle is to combine high-performance fillers (such as carbon nanotubes and ceramic powders) with amine curing agents to form composite materials with high mechanical strength. However, existing commercially available products (typically amine curing systems) have exposed fatal environmental sensitivity defects in actual outdoor field applications: (1) Low temperature (<10℃) failure: The activation energy of amine curing reaction is high (about 60-80kJ / mol), and the reaction rate decreases by about 50% for every 10℃ decrease in temperature. In an environment of 0-5℃, the curing reaction is almost stagnant, and the material is still in a viscous flow state after 48 hours, which cannot provide sufficient early strength to maintain shaft alignment, and the repair will inevitably fail; (2) High temperature (>35℃) burst polymerization: Amine curing is a strongly exothermic reaction (reaction enthalpy of about 95kJ / eq). When applying large volumes or thick coatings, the internal heat cannot be dissipated in time, resulting in "thermal runaway". The system temperature can rise sharply to over 150℃, causing low molecular weight substances to boil and generate a large number of bubbles. After curing, the volume shrinkage rate is as high as 3-5%, and the material becomes brittle and cracked; (3) Incomplete curing in high humidity (RH>75%): Water molecules are strong polymerization inhibitors of amine curing agents. The active hydrogen in water molecules will compete with the epoxy groups for the active sites on the amine groups, forming a hydrogen bond passivation layer; at the same time, water molecules promote the carbonation of amines. Ultimately, this leads to a 30-50% decrease in crosslinking density, and serious deterioration of the hardness, bonding strength and resistance to media corrosion of the repair layer.

[0005] Existing solutions are mostly passive adaptations: setting up temperature and humidity-controlled tents, using electric blankets for heating, and adding latent curing agents (such as dicyandiamide, but which requires temperatures above 120°C to activate). These methods not only increase the number of processes and extend the construction period, but also do not fundamentally solve the problem of the material's dependence on the environment. Summary of the Invention

[0006] The technical problem to be solved by this invention is to address the technical defects of existing carbon nanopolymer repair materials (especially amine curing systems) such as curing stagnation at low temperatures, explosive polymerization at high temperatures, and incomplete curing under high humidity, by providing a carbon nanopolymer repair material for gearbox shaft repair, its preparation method, and repair process.

[0007] To achieve the above objectives, this application adopts the following technical solution: A carbon nanotube polymer repair material for auxiliary repair of gearbox shafts comprises separately packaged components A and B, which are mixed in a mass ratio of A:B = 100:(4~10) before use. Component A contains an epoxy resin matrix and functional additives; component B contains a multi-mechanism composite curing system.

[0008] Component A, by mass parts, includes the following components: 100 parts epoxy resin; 3-20 parts of reactive diluent; 0.5-5 parts of two-dimensional layered thermally conductive filler; Thixotropic agent 0.2-4 parts; Component B, by mass parts, includes the following components: 15-30 parts of aromatic polythiols containing dynamic covalent bonds; 5-12 parts of modified dicyandiamide derivative; 0.5-3 parts of cationic latent initiator; 0.2-2 parts of imidazole accelerator.

[0009] Preferably, the epoxy resin is a combination of at least two of the following: bisphenol A type epoxy resin (such as E-51, E-44), bisphenol F type epoxy resin (such as NPEF-170), and alicyclic epoxy resin (such as TTA-21).

[0010] In the above scheme, bisphenol type provides rigidity, alicyclic type provides weather resistance and low viscosity, and the combination can optimize mechanical properties and processability.

[0011] Preferably, the active diluent is one or more of cashew phenol glycidyl ether, tert-butylphenyl glycidyl ether, and hexanediol diglycidyl ether.

[0012] Preferably, the two-dimensional layered thermally conductive filler is a hexagonal boron nitride nanosheet, molybdenum disulfide nanosheet, or graphene nanosheet that has been surface-functionalized with a silane coupling agent.

[0013] In the above scheme, a silane coupling agent (such as KH-560) is used to graft the surface onto the epoxy resin, improving its dispersibility and interfacial bonding in the epoxy resin. Utilizing its high thermal conductivity anisotropy, a "thermal channel" is formed within the coating, rapidly diffusing locally concentrated reaction heat laterally and preventing the formation of high-temperature hotspots.

[0014] Preferably, the thixotropic agent is fumed silica or organobentonite.

[0015] Preferably, the aromatic polythiol containing dynamic covalent bonds is a benzenedithiol or benzenetrithiol derivative containing borate ester bonds, with the specific structural formula: Ar-(S-R1). n Ar is a benzene ring or biphenyl ring, and R1 is an alkyl chain of a five-membered or six-membered ring containing borate esters. It is prepared by condensation cyclization of an aromatic diboronic acid compound and a thiol-containing hydroxyl compound under dehydration conditions.

[0016] In the above scheme, the borate ester bond is rapidly formed at low temperature through condensation reaction, providing early strength, while it can be reversibly hydrolyzed under high temperature or acid conditions to release stress and achieve adaptive adjustment of curing shrinkage stress.

[0017] Preferably, the modified dicyandiamide derivative is an aliphatic diamine-modified dicyandiamide, whose melting point is 30-70°C lower than that of unmodified dicyandiamide.

[0018] Preferably, the cationic latent initiator is a diaryliodonium salt or a triarylsulfonium salt, and the counter anion is SbF6. － PF6 － BF4 － One of them.

[0019] Preferably, the transition metal complex is one of zinc acetylacetonate, copper acetylacetonate, or iron acetylacetonate.

[0020] Preferably, the imidazole accelerator is one of 2-ethyl-4-methylimidazolium and 1-benzyl-2-methylimidazolium.

[0021] Preparation of component A: According to the specified ratio, epoxy resin, reactive diluent, two-dimensional layered thermally conductive filler, and thixotropic agent are sequentially added to a double planetary mixer. The mixture is first stirred at low speed (200 rpm) for 15 minutes, then at high speed (800 rpm) for 30 minutes, while simultaneously activating circulating water cooling (reactor temperature ≤40℃). The mixture is then dispersed 3-5 times using a three-roll mill to control the fineness to ≤25μm. Finally, it is degassed under a vacuum of -0.09MPa for 20 minutes, then discharged and packaged.

[0022] Preparation of component B: The process was carried out in a glove box under nitrogen protection. Aromatic polythiols containing dynamic covalent bonds, modified dicyandiamide derivatives, cationic latent initiators, transition metal complexes, and imidazole promoters were added to a ball mill jar according to the specified ratio. Zirconia balls (material-to-ball ratio 1:2) were added, and the mixture was ball-milled at 200 rpm for 2 hours. The mixture was then passed through a 120-mesh sieve and packaged.

[0023] A process for on-site repair of a gearbox shaft using the aforementioned carbon nanotube polymer repair material (as shown in Figure 3) includes the following steps: 1. Surface engineering treatment: Degreasing: Use environmentally friendly degreasing agents (such as acetone or ethanol) to clean worn areas and ensure that there is no oil residue.

[0024] Roughening: Dry sandblasting is used with 46-mesh brown corundum abrasive, compressed air pressure of 0.5-0.7MPa, and sandblasting angle of 70-90° to achieve a surface roughness of Ra6-12μm, forming a fresh, clean, and activated metal surface.

[0025] Blowing: Thoroughly blow away any remaining dust from the surface with dry, oil-free compressed air.

[0026] 2. Mixing ratio: Adjust the mixing ratio within the recommended range of A:B = 100:5 to 100:9, depending on the ambient temperature and humidity. Use a higher ratio (increase component B) for low-temperature and high-humidity environments, and a lower ratio for high-temperature and low-humidity environments.

[0027] 3. Coating process: Stir the mixed materials vigorously for 2-4 minutes until the color is completely uniform.

[0028] The principle of "thin layer, multiple coatings" is adopted. First, take a small amount of the mixture with a scraper and press it firmly into the deepest part of the worn area to ensure that there are no voids between the mixture and the substrate. The thickness of this layer should be controlled at 0.1-0.2mm.

[0029] Subsequent coatings are applied layer by layer, with each layer not exceeding 1mm in thickness, until the design dimensions are restored (with a machining allowance of 0.3-0.5mm).

[0030] For journal mating surfaces, special centering fixtures or molds can be used for forming.

[0031] 4. Environmentally adaptive curing: After coating, it can be placed directly in the construction environment without human intervention.

[0032] Low-temperature environment (0-10℃): The material first reaches surface dryness within 30-60 minutes through mercapto-epoxy click chemistry, providing sufficient "green strength" to maintain axial alignment. Subsequently, the heat released by the curing reaction gradually accumulates, triggering the modified dicyandiamide derivative and cationic latent initiator to complete deep curing. Complete curing takes 24-36 hours.

[0033] High-temperature environment (30-45℃): The two-dimensional layered thermally conductive filler network rapidly dissipates the heat of reaction, avoiding hot spots; the dynamic borate ester bonds are moderately "opened" at high temperatures, exchanging and releasing internal stress to prevent cracking. Complete curing in 4-8 hours.

[0034] High humidity environment (RH70-90%): The cationic polymerization mechanism dominates the curing process. Water molecules not only do not poison the reaction, but also participate in the initiation process as a proton source, ensuring the crosslinking density.

[0035] When accelerated curing is required, infrared lamps or hot air guns can be used to assist heating of the repair area, controlling the surface temperature of the shaft to not exceed 80°C. In this case, the curing time can be shortened to 2-8 hours.

[0036] 5. Post-processing: After curing, it can be restored to the original design dimensions and tolerances by hand scraping, filing or lathe finishing.

[0037] This invention achieves adaptive curing across the entire spectrum of environments (0-45℃, RH≤90%) through the synergistic effect of four mechanisms: dynamic covalent bonds, cationic polymerization, modified dicyandiamide, and two-dimensional thermally conductive fillers. This allows for the coexistence, zoned activation, and relay operation of thiol groups for low temperatures, cationic groups for high humidity, dicyandiamide for deep curing, thermal conductivity for temperature control, and dynamic bonds within the same system. This results in a wide-temperature and wide-humidity adaptive curing effect that is unattainable with a single mechanism or simple combination. Its overall performance (especially environmental tolerance and curing stress control) is significantly superior to existing technologies.

[0038] Compared with the prior art, this application has the following beneficial effects: 1. The carbon nanoparticle polymer repair material of this invention has groundbreaking environmental adaptability: it can achieve complete curing in extreme environments ranging from 0°C to 45°C and relative humidity ≤90%. It exhibits rapid shaping at low temperatures, no explosive polymerization or bubble formation at high temperatures, and high degree of curing retention under high humidity.

[0039] 2. The carbon nanoparticle polymer repair material of this invention features dynamic stress regulation, achieving ultra-low shrinkage: it utilizes the reversible exchange reaction of dynamic covalent bonds (boronate bonds, disulfide bonds) to dissipate volume shrinkage stress during the curing process in real time. The low volume shrinkage rate significantly improves the interfacial bonding durability between the repair layer and the substrate, and exhibits high shear strength retention after hygrothermal aging.

[0040] 3. The carbon nanoparticle polymer repair material of this invention features multi-component synergy and adjustable performance: the multifunctional design of component B endows the material with "intelligent" characteristics. Users can fine-tune the mixing ratio within the recommended range according to the severity of the site conditions to achieve a balance between curing speed and operation time.

[0041] 4. The carbon nanoparticle polymer repair material of this invention exhibits excellent performance: the final cured product has high tensile shear strength, high compressive strength, and high Shore hardness (D), with comprehensive mechanical properties surpassing most commercially available products. Simultaneously, the aromatic structure endows it with excellent resistance to oil, acids, and alkalis.

[0042] 5. The carbon nanoparticle polymer repair material of the present invention has significant economic and social benefits: it enables rapid repair of heavy-duty reducer shafts without disassembly, heating, or constant temperature workshops, with a short average repair time and greatly reduces downtime losses. Attached Figure Description

[0043] Figure 1 The graph shows a comparison of the curing exothermic curves of the carbon nanoparticle polymer repair materials of Examples 1, 2 and Comparative Example 1 of the present invention.

[0044] Figure 2 The bar chart shows the comparison of the curing degree of the carbon nanopolymer repair materials of Example 1 and Comparative Example 1 under different environmental humidity conditions.

[0045] Figure 3 This is a process flow diagram illustrating the repair material used in this invention for repairing worn areas on a speed reducer shaft.

[0046] Figure 4 The infrared spectrum of the aromatic dithiol containing the dynamic bond of the borate ester in this invention is shown.

[0047] Figure 5 The infrared spectrum of the modified dicyandiamide derivative of this invention is shown. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the following embodiments are only for explaining the invention and not for limiting it. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0049] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0050] I. The preparation method of aromatic dithiols (denoted as BDB) containing borate ester dynamic bonds is as follows: To a 500 mL four-necked flask equipped with a mechanical stirrer (200-400 rpm), a Dean-Stark water separator (with a reflux condenser), a nitrogen inlet, and a thermometer, add sequentially 1,4-phenylenediboric acid (0.2 mol, 33.2 g), 2,3-dimercapto-1-propanol (0.44 g, 54.6 g, molar ratio 1:2.2), anhydrous toluene (250 mL, as an azeotropic dehydrating agent), p-toluenesulfonic acid monohydrate (0.004 mol, 0.76 g, catalyst), and 4A molecular sieve (20 g, dehydrating agent). Nitrogen purging is initiated (flow rate 0.5 L / min, for 15 min). The mixture is heated to 115 °C under reflux. During the reaction, water and toluene form an azeotrope, which is continuously separated by the water separator. The reaction progress is determined by monitoring the amount of water generated in the water separator (theoretically, 0.4 mol of water is produced, approximately 7.2 mL). Continue the reaction for 8 hours until the actual collected water volume is close to or exceeds 90% of the theoretical value.

[0051] After the reaction was complete, the mixture was cooled to 60°C and filtered to remove the molecular sieve. Toluene was removed by rotary evaporation (50°C water bath, vacuum -0.095MPa) to obtain an orange-yellow viscous crude product. The crude product was dissolved in 100 mL of ethyl acetate, transferred to a separatory funnel, and washed twice (50 mL each time) with 5% NaHCO3 aqueous solution to neutralize the catalyst, followed by washing with saturated brine until neutral. The organic phase was dried overnight with anhydrous sodium sulfate. After filtration, the solvent was removed by rotary evaporation, and finally dried in a vacuum drying oven at 40°C for 24 hours to obtain product BDB (IR spectrum shown in [reference needed]). Figure 4 ).

[0052] II. The preparation method of the modified dicyandiamide derivative (m-DICY) is as follows: In a 250 mL three-necked flask, dicyandiamide (0.3 mol, 25.2 g), hexamethylenediamine (0.15 mol, 17.4 g), n-butanol (100 mL), and glacial acetic acid (0.5 mL, catalyst) were added. The mixture was heated to 115 °C and refluxed for 6 hours. During the reaction, the solution gradually became clear from its turbid state. After the reaction was completed, the mixture was cooled to room temperature, and white crystals precipitated. The crystals were filtered, and the filter cake was washed three times with a mixture of n-butanol and acetone (volume ratio 1:2). The crude product was recrystallized from ethanol and dried in a vacuum drying oven at 60 °C for 12 hours to obtain a white powdery m-DICY with a melting point of approximately 143 °C (the melting point of the original dicyandiamide was 210 °C) (see infrared spectrum). Figure 5 ).

[0053] III. The preparation method of two-dimensional layered thermally conductive filler surface functionalized boron nitride nanosheets (f-BN) is as follows: 5g of hexagonal boron nitride powder (particle size <1μm) was mixed with 100mL of isopropanol, and ultrasonic exfoliation was performed in an ice-water bath (400W power, 2 hours, 5-second intervals). The exfoliated suspension was centrifuged at 2000rpm for 20 minutes, and the supernatant was collected to obtain a boron nitride nanosheet dispersion. After centrifugation and concentration, the nanosheet solid was collected and redispersed in 100mL of anhydrous ethanol.

[0054] Add 2.5 g of silane coupling agent KH-560 (γ-glycidoxypropyltrimethoxysilane), adjust the pH to 5.0 with acetic acid, and stir the reaction at 60 °C for 6 hours. After the reaction is complete, centrifuge, wash three times with anhydrous ethanol, and dry in a vacuum drying oven at 60 °C for 24 hours to obtain f-BN.

[0055] IV. The preparation method of functionalized graphene nanosheets (fG) on the surface of two-dimensional layered thermally conductive fillers is as follows: Add 5g of graphene nanosheets to 200mL of isopropanol and place in a 1000mL beaker. Use a probe-type ultrasonic cell disruptor (600W power, 15mm diameter amplitude rod) to sonicate for 3 hours in an ice-water bath (2 seconds on, 3 seconds off). After sonication, transfer the black suspension to a centrifuge tube and centrifuge at 2500rpm for 20 minutes. Collect the supernatant dispersion and centrifuge at 10000rpm for 30 minutes. Collect the precipitate to obtain a concentrated few-layer graphene nanosheet wet cake, redisperse it in 100mL of anhydrous ethanol, add 20mL of deionized water, and slowly add glacial acetic acid dropwise to adjust the pH to 5.0.

[0056] Add 3g of KH-560 silane coupling agent and stir magnetically in a 60℃ water bath for 8 hours. After the reaction is complete, centrifuge the suspension at 8000rpm for 15 minutes, collect the black precipitate, wash it three times with anhydrous ethanol, and dry it in a 60℃ vacuum drying oven for 24 hours to obtain a black powder fG.

[0057] Example 1 This embodiment provides a carbon nanotube polymer repair material for auxiliary repair of gearbox shafts, the composition and formulation of which are as follows: Component A: Bisphenol A type epoxy resin (E-51, epoxy value 0.51eq / 100g): 70 parts Bisphenol F type epoxy resin (NPEF-170, epoxy value 0.60 eq / 100g): 30 parts Cardolite NC-513: 12 parts Surface-functionalized boron nitride nanosheets (f-BN, prepared by the aforementioned method): 2.5 parts Fumed silica (AEROSILR 972): 3 parts Component B: Aromatic dithiols containing boronic acid ester bonds (BDB, prepared according to the aforementioned method): 22 parts Modified dicyandiamide (m-DICY, prepared according to the aforementioned method): 8 parts Diphenyliodonium hexafluorophosphate (Irgacure250): 2.5 parts Zinc acetylacetonate (Zn(acac)2): 0.8 parts 2-Ethyl-4-methylimidazole (2E4MZ): 1.5 parts Preparation method of carbon nanoparticle polymer repair material for gearbox shaft repair: Component A: Weigh each raw material according to the ratio, add it to the planetary mixing vessel, stir and disperse it evenly, then pass it through a three-roll mill three times, vacuum degas it, and discharge it.

[0058] Component B: Under nitrogen protection, add all raw materials into a ball mill jar, ball mill for 2 hours, and pass through a 120-mesh sieve.

[0059] Repair process using carbon nanotube polymer repair material as an auxiliary material for gearbox shaft repair: The object to be repaired is the output shaft (material 45# steel) of the reducer of a bucket elevator in a cement plant. The journal wear is 0.45mm. The ambient temperature is 12℃ and the relative humidity is 82%.

[0060] 1. Surface treatment: Sandblasting to Ra8-10μm.

[0061] 2. Mixing: Weigh 100g of component A and 7.5g of component B, and stir for 3 minutes.

[0062] 3. Coating: Follow the "base coat - thin layer multi-coat" process to restore the shaft diameter.

[0063] 4. Curing: The surface is touchable after 2 hours (no fingerprints when pressed with a finger). The highest measured exothermic temperature during the curing process is 68℃ (ambient temperature 12℃). It is fully cured after 16 hours and then machined.

[0064] Performance testing: Tensile shear strength (GB / T7124-2008): 24.3 MPa; Volume shrinkage rate (density method): 0.52%; Shore hardness D (GB / T2411-2008): 87; Degree of cure (acetone extraction method, cured at RH 82%): 94.1%; Resistance to media (80℃ oil immersion for 7 days, strength retention rate): 91%.

[0065] Example 2 This embodiment simulates outdoor construction in northern China during winter, with an ambient temperature of -2℃ (simulated using a low-temperature constant temperature chamber) and a relative humidity of 55%. The formula was adjusted to enhance low-temperature start-up capability.

[0066] Component A: Basically the same as in Example 1, except that f-BN is replaced with an equal number of surface-functionalized graphene nanosheets (f-G, prepared according to the aforementioned method).

[0067] Component B: The adjusted proportions are: BDB 28 parts, m-DICY 5 parts, Irgacure 250 3 parts, Zn(acac) 21.2 parts, and 2E4MZ 2 parts. The total number of parts is adjusted to 39.2 parts.

[0068] Mixing ratio: A:B = 100:8.5.

[0069] Curing performance: Approximately 45 minutes after application, a gel with a certain strength has formed when the surface is lightly touched with a finger (setting). After 2 hours at -2°C, the internal temperature rises to 12°C. It fully cures after 36 hours.

[0070] Performance testing: Tensile shear strength (cured at -2℃): 21.5 MPa; Volume shrinkage rate: 0.48%; Hardness (Shore D): 84; Low-temperature curing degree (measured after 24 hours at 0℃): 92.8%.

[0071] Example 3 This embodiment simulates an indoor environment during the rainy season in southern China, with a temperature of 38°C and a relative humidity of 95%. The formula was adjusted to enhance resistance to explosive polymerization and moisture.

[0072] Component A: Replace the reactive diluent with 15 parts of tert-butylphenyl glycidyl ether; increase the amount of f-BN added to 3.5 parts.

[0073] Component B: The adjusted ratio is: BDB 18 parts, m-DICY 10 parts, Irgacure 250 4 parts, Zn(acac) ２ 0.5 servings, 1 serving of 2E4MZ. Total servings: 33.5 servings.

[0074] Mixing ratio: A:B = 100:5.5.

[0075] Curing performance: After coating, the pot life is shortened to approximately 20 minutes due to the high temperature. The curing process is exothermic and stable, with a maximum test temperature of only 78℃ (ambient temperature 38℃). No bubbles or cracks are visible on the material surface. The cationic polymerization mechanism functions normally at 95% humidity, and complete curing occurs after 6 hours.

[0076] Performance testing: Tensile shear strength: 23.8 MPa; Volume shrinkage rate: 0.55%; Hardness (ShoreD): 89; High temperature and high humidity curing degree: 95.2%.

[0077] Comparative Example 1 (Commercially available typical amine-cured carbon nanoparticle polymer repair material) Purchased from a well-known brand (main components are bisphenol A epoxy + modified amine + carbon nanotubes).

[0078] test: 1. Low-temperature test (5℃, RH60%): Apply according to the instructions. 12 hours after application, the material surface remains sticky and fluid, failing to provide effective strength. After 48 hours, it is barely palatable, but with extremely low hardness (ShoreD<40) and a tensile shear strength of only 3.2MPa.

[0079] 2. High temperature test (40℃, RH60%): The pot life after mixing is about 8 minutes. 15 minutes after coating, the temperature at the center of the material rises sharply, exceeding 150℃, and a large amount of white smoke is emitted. After curing, the material is loose and porous, extremely brittle, and breaks easily upon contact.

[0080] 3. High humidity test (25℃, RH 92%): After 72 hours of curing, the surface turned white, and the interior was not fully cured. The degree of curing measured by acetone extraction was only 56.8%. Tensile shear strength was 6.5 MPa.

[0081] Comparative Example 2 Component A consists of 100 parts of E-51 epoxy; Component B consists of 8 parts of Irgacure 250, with no other curing agent.

[0082] Test (25℃, RH80%): Although it can be cured, its volume shrinkage rate reaches 2.8%, its final hardness is only Shore D65, its tensile shear strength is 12.3 MPa, and its oil resistance is poor.

[0083] Comparative Example 3 Component A consists of 100 parts of E-51; Component B consists of 25 parts of pentaerythritol tetramercaptoacetate and 5 parts of DMP-30 accelerator.

[0084] Test (5℃, RH 65%): It sets within 2 hours, but after 24 hours, the tensile shear strength only reaches 15.6 MPa, and in a high humidity (RH90%) environment, the degree of curing drops to 70%, and the surface becomes sticky.

[0085] Comparative Example 4 The other formulations are exactly the same as in Example 1, except that f-BN is not added to component A.

[0086] Test (35℃, RH 50%, 8mm thick coating): The peak temperature at the center reached 112℃, macroscopic cracks appeared inside the material, the volume shrinkage rate was 1.8%, and the tensile shear strength decreased to 18.2MPa.

[0087] The carbon nanoparticle polymer repair materials of Examples 1, 2, and 1 were repaired at 25°C, 5°C, and 25°C, respectively, and the temperature change at the center of the repair layer was tested (all tests used embedded K-type thermocouples (0.5 mm in diameter, ±0.3°C accuracy) to monitor the geometric center temperature of the repair layer in real time, the thickness of the repair layer was uniformly 8 mm, and the mold was a cylindrical polytetrafluoroethylene mold of Φ30 mm × 10 mm). The dynamic curve of the temperature change of the center of the repair layer over time is shown in Figure 1.

[0088] As can be seen from Figure 1, the carbon nanoparticle polymer repair material of the present invention can achieve stable exothermic reaction at room temperature without the risk of explosive polymerization; at a low temperature of 5°C, it can spontaneously raise the system temperature by 24.6°C to achieve reliable low-temperature curing; the commercially available amine system exhibits explosive polymerization and runaway under the same room temperature conditions.

[0089] The relative humidity (RH) was set at three levels: 50% (normal dry environment), 70% (humid environment), and 90% (extreme high humidity environment) to investigate the curing ability (degree of curing) of the carbon nanoparticle polymer repair materials of Example 1 and Comparative Example 1 under different humidity conditions. The degree of curing was determined by acetone extraction, and the degree of curing was calculated as (dry weight of sample after extraction / dry weight of sample before extraction) × 100%. The results are shown in Figure 2.

[0090] As can be seen from Figure 2, the degree of curing of the carbon nanopolymer repair material of the present invention remains at 93.5% at RH 90%, while the degree of curing of the commercially available amine system drops to 58.2% under the same conditions, proving that the present invention has excellent high humidity resistance.

[0091] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A carbon nanoparticle polymer repair material for auxiliary repair of gearbox shafts, characterized in that, It consists of separately packaged component A and component B, wherein the mass ratio of component A to component B is 100:4 to 100:10; Component A comprises, by mass parts: 100 parts epoxy resin; 3-20 parts of reactive diluent; 0.5-5 parts of two-dimensional layered thermally conductive filler; Thixotropic agent 0.2-4 parts; Component B comprises, by mass parts: 15-30 parts of aromatic polythiols containing dynamic covalent bonds; 5-12 parts of modified dicyandiamide derivative; 0.5-3 parts of cationic latent initiator; 0.1-1 part of transition metal complex; 0.2-2 parts of imidazole accelerator.

2. The carbon nanoparticle polymer repair material for auxiliary repair of gearbox shafts according to claim 1, characterized in that, The epoxy resin is a combination of at least two of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and alicyclic epoxy resin; the reactive diluent is one or more of cashew phenol glycidyl ether, tert-butylphenyl glycidyl ether, and hexanediol diglycidyl ether.

3. The carbon nanoparticle polymer repair material for auxiliary repair of gearbox shafts according to claim 1, characterized in that, The two-dimensional layered thermally conductive filler is a hexagonal boron nitride nanosheet, molybdenum disulfide nanosheet, or graphene nanosheet that has been surface-functionalized with a silane coupling agent; the thixotropic agent is fumed silica or organobentonite.

4. The carbon nanoparticle polymer repair material for auxiliary repair of gearbox shafts according to claim 1, characterized in that, The aromatic polythiols containing dynamic covalent bonds are benzene dithiols or benzene trithiols derivatives containing borate ester bonds, which are prepared by condensation cyclization of aromatic diboronic acid and thiol-containing hydroxyl compounds under dehydration conditions.

5. The carbon nanoparticle polymer repair material for auxiliary repair of a speed reducer shaft according to claim 1, characterized in that, The modified dicyandiamide derivative is an aliphatic diamine-modified dicyandiamide; the cationic latent initiator is a diaryliodonium salt or a triarylsulfonium salt, and its counter anion is SbF6. － PF6 － BF4 － One of them.

6. The carbon nanoparticle polymer repair material for auxiliary repair of a speed reducer shaft according to claim 1, characterized in that, The transition metal complex is one of zinc acetylacetonate, copper acetylacetonate, or iron acetylacetonate; the imidazole accelerator is one of 2-ethyl-4-methylimidazolium or 1-benzyl-2-methylimidazolium.

7. A method for preparing a carbon nanoparticle polymer repair material for auxiliary repair of a gearbox shaft according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Preparation of aromatic polythiols containing dynamic covalent bonds: In the presence of an inert atmosphere and a dehydrating agent, aromatic diboronic acid and thiol-containing hydroxyl compounds are reacted in an organic solvent at a molar ratio of 1:2 to 1:2.5 under reflux for 6-12 hours at 100-130℃, and the target product is obtained by separation and purification. (2) Preparation of modified dicyandiamide derivatives: In the presence of an acid catalyst, dicyandiamide and aliphatic diamine were refluxed in an alcohol solvent at 100-140℃ for 4-8 hours in a molar ratio of 2:1 to 3:

1. After cooling, crystallization and recrystallization, a white powder was obtained. (3) Surface functionalization of two-dimensional layered thermally conductive filler: After ultrasonic exfoliation, the two-dimensional layered thermally conductive filler is reacted with silane coupling agent in an alcohol-water mixed solvent at pH 4-6 at 50-80℃ for 4-8 hours, and then washed and dried to obtain the functionalized filler. (4) Preparation of component A: Epoxy resin, reactive diluent, functionalized two-dimensional filler and thixotropic agent are mixed according to the formula, dispersed by three-roll milling to fineness ≤25μm, and degassed under vacuum to obtain component A; (5) Preparation of component B: Under an inert atmosphere, aromatic polythiols containing dynamic covalent bonds, modified dicyandiamide derivatives, cationic latent initiators, transition metal complexes, and imidazole accelerators are ground and mixed evenly according to the formula, and then sieved to obtain component B.

8. The method for preparing a carbon nanoparticle polymer repair material for auxiliary repair of a speed reducer shaft according to claim 7, characterized in that, The organic solvent in step (1) is toluene, xylene or cyclohexane; the dehydrating agent is a molecular sieve or an azeotropic dehydrating agent; the aliphatic diamine in step (2) is hexamethylenediamine, butanediamine or decanediamine; the acid catalyst is glacial acetic acid or p-toluenesulfonic acid.

9. A repair process for repairing a gearbox shaft using the carbon nanotube polymer repair material according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Surface treatment: The worn parts of the reducer shaft are degreased and then sandblasted to roughen the surface so that the surface roughness reaches Ra6-15μm, and then blown clean with dry compressed air; (2) Adaptive mixing ratio: Based on the temperature and humidity of the construction environment, select the mixing ratio within the range of 100:4 to 100:10 of the mass ratio of component A to component B. Use a higher ratio for low temperature and high humidity environments and a lower ratio for high temperature and low humidity environments. (3) Mixing and coating: Weigh component A and component B according to the selected ratio, mix and stir for 2-4 minutes until the color is uniform, then apply the mixed material to the worn area, with a base coat thickness of 0.1-0.2 mm and compact it, then coat layer by layer to the designed thickness; (4) Environmental adaptive curing: Place the coated reducer shaft directly in the construction environment. Under the conditions of ambient temperature 0-45℃ and relative humidity ≤90%, no additional heating or dehumidification is required. The material will set in 30-120 minutes and be fully cured in 4-36 hours.

10. The repair process according to claim 9, characterized in that, In step (4), when accelerated curing is required, infrared lamps or hot air guns can be used to assist heating of the repair area, and the surface temperature of the shaft can be controlled to not exceed 80°C. At this time, the curing time can be shortened to 2-8 hours.

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