Modified carbon fiber with multi-scale synergistically enhanced lubricating composite structure on surface as well as preparation method and application of modified carbon fiber

Abstract

The invention provides a modified carbon fiber with a multi-scale synergistically enhanced lubricating composite structure on the surface and a preparation method and application thereof, and belongs to the technical field of composite material preparation and friction reduction and wear resistance. The preparation method comprises the following steps: firstly, modifying carbon fibers through ferric oxide nanoparticles and graphite-phase carbon nitride nanosheets to obtain modified carbon fibers with a multi-scale synergistically enhanced lubricating composite structure formed by stacking the ferric oxide nanoparticles / graphite-phase carbon nitride nanosheets on the surface; the modified carbon fiber and resin matrix diamine type polybenzoxazine resin can be used for preparing the resin composite material with antifriction and wear-resistant effects, and the modified carbon fiber can be used for remarkably reducing the friction coefficient and wear rate of the resin composite material on the basis of keeping high mechanical strength and high temperature resistance of the resin composite material; the resin composite material can be used for preparing parts working under oil-free or heavy-load high-speed operation conditions, the service life of the parts is prolonged, the operation reliability is improved, and good practicability is achieved.

Description

Technical Field

[0001] This invention belongs to the field of composite material preparation and friction reduction and wear resistance technology, specifically relating to a modified carbon fiber with a multi-scale synergistic lubrication composite structure on its surface, its preparation method and application. Background Technology

[0002] Carbon fiber reinforced polymer (CFRP) composites possess advantages such as high specific strength, high specific modulus, and corrosion resistance, leading to their widespread application in aerospace, precision machinery, and the automotive industry. However, in many moving parts (sliders, bearings, gears, etc.), especially under extreme and harsh conditions such as vacuum, high speed, and high load, the surface / internal components of composite parts often experience performance degradation and even lubrication failure due to friction and wear. This has become a key bottleneck restricting their further application. Typically, most CFRP composites experience severe adhesive wear and abrasive wear under dry friction or boundary lubrication conditions due to insufficient lubrication, fiber debonding and pull-out, and softening and decomposition of the resin matrix, resulting in a sharp increase in the coefficient of friction and wear rate. Therefore, modification of the composite material is necessary to improve its load-bearing capacity and lubricity.

[0003] Traditional modification methods involve adding lubricating and reinforcing functional fillers, such as graphite, molybdenum disulfide, polytetrafluoroethylene, and ceramic particles, to the resin to improve the load-bearing and lubrication properties of the composite material. However, this method suffers from problems such as difficulty in uniformly dispersing the filler, weak bonding with the resin, easy detachment, and a certain degree of sacrifice in the mechanical properties of the composite material. In addition, researchers have also carried out physical or chemical modifications to the composite material, such as coating the fiber surface with nanomaterials to improve the mechanical strength and tribological properties of the composite material. However, physical methods often involve high-energy ray activation treatment, which often damages the surface structure of carbon fibers to some extent and reduces the strength of the carbon fibers themselves. Chemical modification techniques often face the problem of limited bonding force between nanoparticles and fibers, easy detachment during long-term friction, and focus more on improving the material composition, while neglecting to fundamentally solve the friction reduction and wear resistance problems under extreme and harsh working conditions, such as the single lubrication mechanism and the inability to achieve long-term lubrication, from the perspective of "structural design", especially multi-scale and multi-level structural synergy.

[0004] Therefore, a new carbon fiber surface modification technology is needed to prepare composite materials with low and stable friction coefficients and good wear resistance. Summary of the Invention

[0005] To address some shortcomings in existing technologies, this invention provides a modified carbon fiber with a multi-scale synergistic lubrication-enhancing composite structure on its surface, along with its preparation method and applications. Firstly, the invention modifies carbon fibers using iron oxide nanoparticles and graphite-phase carbon nitride nanosheets to obtain a modified carbon fiber with a multi-scale synergistic lubrication-enhancing composite structure formed by the stacking of iron oxide nanoparticles and graphite-phase carbon nitride nanosheets. This modified carbon fiber can be combined with a diamine-type polybenzoxazine resin matrix to prepare a resin composite material with friction-reducing and wear-resistant effects. The modified carbon fiber can significantly reduce the coefficient of friction and wear rate of the resin composite material while maintaining its high mechanical strength and high temperature resistance. This resin composite material can be used to prepare components operating under oil-free or heavy-load, high-speed conditions (such as high-speed CNC machine tool bearings and heavy-duty sliding bearings), extending component life and improving operational reliability, demonstrating excellent practicality.

[0006] To achieve the above-mentioned technical objectives, the present invention employs the following technical means:

[0007] The present invention first provides a modified carbon fiber with a multi-scale synergistic lubrication-enhancing composite structure on its surface; the modified carbon fiber has a multi-scale synergistic lubrication-enhancing composite structure constructed in situ on its surface, the multi-scale synergistic lubrication-enhancing composite structure being formed by the stacking of iron oxide nanoparticles and graphite-phase carbon nitride nanosheets.

[0008] The iron oxide nanoparticles are hematite α-Fe2O3, with a particle size of approximately 50-100 nm;

[0009] The graphitic carbon nitride nanosheets are distributed in an "upright" state on the surface of the modified carbon fiber.

[0010] The present invention also provides a method for preparing the above-mentioned modified carbon fiber, the method comprising:

[0011] (1) The carbon fibers with surface impurities removed were placed in a Tris-HCl buffer solution containing tannic acid (TA) and polyamide-amine (PAMAM) and shaken to react. After the reaction was completed, the carbon fibers were filtered, washed and dried to obtain activated carbon fibers with TA-PAMAM grafted on the surface.

[0012] (2) The activated carbon fibers were placed in a mixed solution containing FeCl3·6H2O and surfactant to react. After the reaction was completed, the carbon fibers were washed and dried to obtain carbon fibers with iron oxide grown in situ on the surface.

[0013] (3) The carbon fibers with iron oxide grown in situ on the surface were immersed in a saturated solution of urea. After immersion, the urea coating was fixed by freeze drying. Then, the carbon fibers were calcined under the protection of high-purity nitrogen. After calcination, modified carbon fibers with a multi-scale synergistic enhancement and lubrication composite structure on the surface were obtained.

[0014] Preferably, in step (1), the step of removing surface impurities from carbon fiber includes: soaking carbon fiber in acetone and anhydrous ethanol for 24 hours respectively;

[0015] The Tris-HCl buffer solution containing tannic acid (TA) and polyamide-amine (PAMAM) has a pH of 8.5, an initial concentration of 0.05 mol / L, a final concentration of tannic acid (TA) of 0.5-2.5 mg / mL, and a final concentration of polyamide-amine (PAMAM) of 1.0-4.5 mg / mL.

[0016] The polyamide-amine (PAMAM) comprises a G4.0 generation dendritic macromolecule containing 64 amine groups.

[0017] Preferably, the ratio of carbon fiber with surface impurities removed to Tris-HCl buffer solution containing tannic acid (TA) and polyamide-amine (PAMAM) is 5 g: 40 mL.

[0018] The conditions for the shaking reaction are: slow shaking reaction at room temperature for 48 hours.

[0019] Preferably, in step (2), the solvent of the mixed solution containing FeCl3·6H2O and surfactant is a mixture of anhydrous ethanol and water, with a volume ratio of anhydrous ethanol to water of 1:1; the amount of the mixed solution used is 50 mL.

[0020] The surfactants are polypyrrolidone (PVP) and polyethylene glycol (PEG-400); in the mixture, the final concentration ratio of PVPK30 to PEG-400 is 10 mg / mL: 5 mg / mL.

[0021] The final concentration of FeCl3·6H2O is 0.05~0.1mol / L.

[0022] Preferably, in step (2), the reaction conditions are: a solvothermal reaction at 100-125°C for 24 hours.

[0023] Preferably, in step (3), the soaking time is 5 hours;

[0024] The calcination conditions are as follows: the temperature is increased to 510-530℃ at a rate of 3℃ / min, and the calcination time is 3.5h.

[0025] The present invention also provides the application of the modified carbon fiber with the above-mentioned surface having a multi-scale synergistic enhanced lubrication composite structure in the preparation of resin composite materials with friction-reducing and wear-resistant effects.

[0026] This invention also provides a resin composite material with friction-reducing and wear-resistant effects, wherein the resin composite material uses the above-mentioned modified carbon fiber as a reinforcement; the matrix of the resin composite material is a diamine-type polybenzoxazine resin (poly(PH-ddm), the structural formula of its monomer is:

[0027] .

[0028] Preferably, in the resin composite material, the amount of modified carbon fiber added is 7 wt.% to 12 wt.% of the resin composite material.

[0029] This invention also provides the application of resin composite materials in the wear reduction and wear resistance of friction components in mechanical equipment transmission systems operating under conditions such as oil-free, heavy load, and high speed.

[0030] Preferably, the friction components of the mechanical equipment transmission system include high-speed CNC machine tool bearings and heavy-duty sliding bearings.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] (1) Existing technologies, such as simple replacement or addition of fillers and traditional fiber surface modification, suffer from problems such as damage to fiber structure, complex processes, long cycles, involvement of various organic solvents, and weak bonding and easy detachment of nanoparticles. In contrast, this invention proposes a systematic solution from microstructure optimization design to macroscopic tribological mechanism. This invention uses a process with mild reaction conditions to controllably construct iron oxide nanoparticles with toughening and catalytic induction effects in situ on the fiber surface, and further constructs two-dimensional graphitic carbon nitride nanosheets with "vertical" distribution, good adsorption film formation, and low shear strength on their surface, to achieve a composite structure design with multi-scale, multifunctional synergistic enhancement of lubrication effect on the carbon fiber surface. This invention simultaneously adopts "in-situ construction" and "chemical bonding", which ensures the uniformity and durability of the composite structure on the modified fiber surface, avoiding the problems of particle agglomeration, uneven dispersion, and easy detachment of traditional physical coating or blending methods.

[0033] (2) The modified carbon fiber of the present invention has a multi-scale synergistic enhanced lubrication composite structure on its surface; the modified carbon fiber has a multi-scale synergistic enhanced lubrication composite structure constructed in situ on its surface, which is formed by the stacking of iron oxide nanoparticles and graphite-phase carbon nitride nanosheets. The multi-scale synergistic enhanced lubrication composite structure is composed of iron oxide nanoparticles and graphite-phase carbon nitride, and is firmly bonded to the carbon fiber through chemical bonds. This helps the resin matrix to fully wet and penetrate the interior of the composite structure on the surface of the modified carbon fiber, forming a three-dimensional interlocking "resin-micro-nano composite reinforced interface phase", and can exert a multi-level synergistic lubrication enhancement effect of "friction-induced-interlayer slip-nano rolling". Therefore, the modified carbon fiber can be used to prepare resin composite materials with friction-reducing and wear-resistant effects.

[0034] This invention achieves interface toughening (beneficial for load bearing and wear resistance) through chemical bonding and three-dimensional interlocking interface phases, while providing a continuous and efficient lubrication channel, which can promote the formation of a high-quality friction film at the friction interface (beneficial for friction reduction), thus achieving a systematic improvement in strength, wear resistance and lubricity.

[0035] (3) This invention innovatively combines different lubrication mechanisms such as layered slip and nano-rolling with different scales (nanoparticles, nanosheets, etc.), which not only solves the interface problem of composite materials but also breaks through the limitations of a single lubrication mechanism. Simultaneously, as the friction process proceeds, under the catalytic effect of friction, a strong and high-quality friction film is continuously induced at the friction interface, enabling the composite material to maintain long-term, stable, and low friction. Compared to pure diamine-type polybenzoxazine resin (poly(PH-ddm)), the modified carbon fiber reinforced diamine-type polybenzoxazine resin composite material exhibits a friction coefficient and wear rate reduction of over 45% and 85%, respectively. It is suitable for high-speed CNC machine tool bearings, heavy-duty sliding bearings, etc., and is expected to extend component life and improve operational reliability. Attached Figure Description

[0036] Figure 1 The image shows the FESEM morphology of the microstructure of iron oxide nanoparticles grown in situ on the surface of carbon fibers.

[0037] Figure 2 FESEM image of the microstructure of the multi-scale synergistic lubrication nanocomposite structure on the carbon fiber surface.

[0038] Figure 3 This is a graph showing the variation of the friction coefficient of the resin composite material.

[0039] Figure 4 This is a FESEM image of the microstructure of the worn surface of the friction pair. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0041] Example 1:

[0042] (1) 5g of carbon fiber was soaked in acetone and anhydrous ethanol for 24h respectively to remove surface impurities. Then the dried carbon fiber was placed in 40mL of 0.05mol / L Tris-HCl buffer solution containing 1.0 mg / mL tannic acid (TA) and 2.0 mg / mL polyamide-amine (PAMAM) with a pH of 8.5. The reaction was slowly shaken at room temperature for 48h. After the reaction was completed, the carbon fiber was filtered, washed, and dried under vacuum at 50℃ to obtain activated carbon fiber with TA-PAMAM grafted on the surface.

[0043] (2) The activated carbon fibers obtained in step (1) were placed in 50 mL of a mixed solution of ethanol and water containing 0.05 mol / L FeCl3·6H2O, 10 mg / mL PVP K30 and 5 mg / mL PEG-400 (ethanol:water = 1:1, V / V), and then transferred to a reaction vessel and solvothermal reaction was carried out at 100 °C for 24 h. After the reaction was completed, the reaction product was taken out and subjected to washing, drying and other processes to obtain carbon fibers with iron oxide grown in situ on the surface.

[0044] Figure 1 The image shows the microstructure of carbon fibers with in-situ grown iron oxide nanoparticles on the surface. As can be seen from the image, the iron oxide nanoparticles are uniformly anchored on the carbon fiber surface, and the particle size is about 50-100 nm.

[0045] (3) The carbon fibers with in-situ iron oxide growth obtained in step (2) were immersed in a saturated urea solution for 5 hours, and then freeze-dried to fix the urea coating. Subsequently, they were placed in a tube furnace and heated to 510°C at a rate of 3°C / min, and calcined at this temperature under the protection of high-purity nitrogen for 3.5 hours. After natural cooling, modified carbon fibers with a multi-scale synergistic reinforcement and lubrication composite structure on the surface were obtained.

[0046] Figure 2 The FESEM morphology of the carbon fiber surface microstructure with a multi-scale composite structure is shown in the figure. As can be seen from the figure, the graphitic carbon nitride exhibits a layered structure and is distributed in an "upright" state on the surface of the modified fiber. At the same time, iron oxide nanoparticles distributed on the surface of the carbon fiber can be clearly seen.

[0047] Example 2:

[0048] (1) 5g of carbon fiber was soaked in acetone and anhydrous ethanol for 24h to remove surface impurities. Then the dried carbon fiber was placed in 40mL of 0.05mol / L Tris-HCl buffer solution containing 1.5 mg / mL tannic acid (TA) and 2.5 mg / mL polyamide-amine (PAMAM) with a pH of 8.5. The reaction was slowly shaken at room temperature for 48h. After the reaction was completed, the carbon fiber was filtered, washed, and dried under vacuum at 50℃ to obtain activated carbon fiber with TA-PAMAM grafted on the surface.

[0049] (2) The activated carbon fibers obtained in step (1) were placed in 50 mL of a mixed solution of ethanol and water containing 0.1 mol / L FeCl3·6H2O, 10 mg / mL PVP K30 and 5 mg / mL PEG-400 (ethanol:water = 1:1, V / V), and then transferred to a reaction vessel and solvothermal reaction was carried out at 110 °C for 24 h. After the reaction was completed, the reaction product was taken out and subjected to washing, drying and other processes to obtain carbon fibers with iron oxide grown in situ on the surface.

[0050] (3) The carbon fibers with in-situ iron oxide growth obtained in step (2) were immersed in a saturated urea solution for 5 hours, and then freeze-dried to fix the urea coating. Subsequently, they were placed in a tube furnace and heated to 520°C at a rate of 3°C / min, and calcined at this temperature under the protection of high-purity nitrogen for 3.5 hours. After natural cooling, modified carbon fibers with a multi-scale synergistic reinforcing lubrication composite structure on the surface were obtained.

[0051] Using the modified carbon fiber prepared in this embodiment as the reinforcing phase and diamine-type polybenzoxazine resin (poly(PH-ddm)) as the matrix, with the mass fraction of modified carbon fiber being 10 wt.% of the resin composite material, a resin composite material with friction-reducing and wear-resistant effects was prepared by hot-pressing curing at 220°C and 6 MPa for 8 hours.

[0052] The structural formula of the diamine-type polybenzoxazine resin (poly(PH-ddm)) monomer is:

[0053] .

[0054] The tribological properties of the resin composite material were tested using a ball-disc friction tester. The coefficient of friction was 0.151, and the wear rate was 1.3810. -5 mm 3 / Nm.

[0055] Figure 3 The graph shows the change curve of the friction coefficient of the resin composite material over time. As can be seen from the graph, the friction coefficient changes steadily throughout the process and remains at around 0.15 during the friction stabilization period.

[0056] Figure 4 To illustrate the surface morphology of the steel ball after friction, a stable and uniform friction transfer film is applied to the surface of the steel ball. This friction transfer film can stabilize the friction process and inhibit the friction and wear of the resin composite material.

[0057] Example 3:

[0058] (1) 5g of carbon fiber was soaked in acetone and anhydrous ethanol for 24h respectively to remove surface impurities. Then the dried carbon fiber was placed in 40mL of 0.05mol / L Tris-HCl buffer solution containing 2.5 mg / mL tannic acid (TA) and 4.5 mg / mL polyamide-amine (PAMAM) with a pH of 8.5. The reaction was slowly shaken at room temperature for 48h. After the reaction was completed, the carbon fiber was filtered, washed, and dried under vacuum at 50℃ to obtain activated carbon fiber with TA-PAMAM grafted on the surface.

[0059] (2) The activated carbon fibers obtained in step (1) were placed in 50 mL of a mixed solution of ethanol and water containing 0.08 mol / L FeCl3·6H2O, 10 mg / mL LPV PvK30 and 5 mg / mL PEG-400 (ethanol:water = 1:1, V / V), and then transferred to a reaction vessel and solvothermal reacted at 110 °C for 24 h. After the reaction was completed, the reaction product was taken out and, after washing and drying, carbon fibers with iron oxide grown in situ on the surface were obtained.

[0060] (3) The carbon fibers with in-situ iron oxide growth obtained in step (2) were immersed in a saturated urea solution for 5 hours, and then freeze-dried to fix the urea coating. Subsequently, they were placed in a tube furnace and heated to 530°C at a rate of 3°C / min, and calcined at this temperature under the protection of high-purity nitrogen for 3.5 hours. After natural cooling, modified carbon fibers with a multi-scale synergistic reinforcing lubrication composite structure on the surface were obtained.

[0061] Using the modified carbon fiber prepared in this embodiment as the reinforcing phase and diamine-type polybenzoxazine resin (poly(PH-ddm)) as the matrix, with a mass fraction of 12 wt.% for the modified carbon fiber, a resin composite material with friction-reducing and wear-resistant effects was prepared by hot-pressing curing at 220°C and 6 MPa for 8 hours.

[0062] The tribological properties of the resin composite material were tested using a ball-disc friction tester. The coefficient of friction was 0.146, and the wear rate was 0.9810. -5 mm 3 / Nm.

[0063] Example 4:

[0064] (1) 5g of carbon fiber was soaked in acetone and anhydrous ethanol for 24h to remove surface impurities. Then the dried carbon fiber was placed in 40mL of 0.05mol / L Tris-HCl buffer solution containing 0.5 mg / mL tannic acid (TA) and 2.0 mg / mL polyamide-amine (PAMAM) with a pH of 8.5. The reaction was slowly shaken at room temperature for 48h. After the reaction was completed, the carbon fiber was filtered, washed, and dried under vacuum at 50℃ to obtain activated carbon fiber with TA-PAMAM grafted on the surface.

[0065] (2) The activated carbon fibers obtained in step (1) were placed in 50 mL of a mixed solution of ethanol and water containing 0.1 mol / L FeCl3·6H2O, 10 mg / mL LPV K30 and 5 mg / mL PEG-400 (ethanol:water = 1:1, V / V), and then transferred to a reaction vessel and solvothermal reaction was carried out at 125 °C for 24 h. After the reaction was completed, the reaction product was taken out and subjected to washing, drying and other processes to obtain carbon fibers with iron oxide grown in situ on the surface.

[0066] (3) The carbon fibers with in-situ iron oxide growth obtained in step (2) were immersed in a saturated urea solution for 5 hours, and then freeze-dried to fix the urea coating. Subsequently, they were placed in a tube furnace and heated to 510°C at a rate of 3°C / min, and calcined at this temperature under the protection of high-purity nitrogen for 3.5 hours. After natural cooling, modified carbon fibers with a multi-scale synergistic reinforcement and lubrication composite structure on the surface were obtained.

[0067] Using the modified carbon fiber prepared in this embodiment as the reinforcing phase and diamine-type polybenzoxazine resin (poly(PH-ddm)) as the matrix, with a mass fraction of 7 wt.% for the modified carbon fiber, a resin composite material with friction-reducing and wear-resistant effects was prepared by hot-pressing curing at 220°C and 6 MPa for 8 hours.

[0068] The tribological properties of the resin composite material were tested using a ball-disc friction tester. The coefficient of friction was 0.158, and the wear rate was 2.0110. -5 mm 3 / Nm.

[0069] Example 5:

[0070] (1) 5g of carbon fiber was soaked in acetone and anhydrous ethanol for 24h to remove surface impurities. Then the dried carbon fiber was placed in 40mL of 0.05mol / L Tris-HCl buffer solution containing 2 mg / mL tannic acid (TA) and 3.5 mg / mL polyamide-amine (PAMAM) with a pH of 8.5. The reaction was slowly shaken at room temperature for 48h. After the reaction was completed, the carbon fiber was filtered, washed, and dried under vacuum at 50℃ to obtain activated carbon fiber with TA-PAMAM grafted on the surface.

[0071] (2) The activated carbon fibers obtained in step (1) were placed in 50 mL of a mixed solution of ethanol and water containing 0.08 mol / L FeCl3·6H2O, 10 mg / mL LPV K30 and 5 mg / mL PEG-400 (ethanol:water = 1:1, V / V), and then transferred to a reaction vessel and solvothermal reaction was carried out at 100 °C for 24 h. After the reaction was completed, the reaction product was taken out and subjected to washing, drying and other processes to obtain carbon fibers with iron oxide grown in situ on the surface.

[0072] (3) The carbon fibers with in-situ iron oxide growth obtained in step (2) were immersed in a saturated urea solution for 5 hours, and then freeze-dried to fix the urea coating. Subsequently, they were placed in a tube furnace and heated to 530°C at a rate of 3°C / min, and calcined at this temperature under the protection of high-purity nitrogen for 3.5 hours. After natural cooling, modified carbon fibers with a multi-scale synergistic reinforcing lubrication composite structure on the surface were obtained.

[0073] Using the modified carbon fiber prepared in this embodiment as the reinforcing phase and diamine-type polybenzoxazine resin (poly(PH-ddm)) as the matrix, with a mass fraction of 9 wt.% for the modified carbon fiber, a resin composite material with friction-reducing and wear-resistant effects was prepared by hot-pressing curing at 220°C and 6 MPa for 8 hours.

[0074] The tribological properties of the resin composite material were tested using a ball-disc friction tester. The coefficient of friction was 0.143, and the wear rate was 1.7310. -5 mm 3 / Nm.

[0075] Comparative Example 1:

[0076] Unmodified pure resin material was prepared by hot-pressing curing at 220℃ and 6MPa for 8 hours using diamine-type polybenzoxazine resin (poly(PH-ddm)) as the matrix. Its tribological properties were tested using a ball-disc friction testing machine. The test results showed that its coefficient of friction was 0.297 and its wear rate was 16.410. -5 mm 3 / Nm.

[0077] Unmodified carbon fiber was used as the reinforcement, and diamine-type polybenzoxazine resin (poly(PH-ddm)) was used as the matrix, with the unmodified carbon fiber comprising 10 wt.% of the composite material. The composite material was prepared by hot-press curing at 220℃ and 6 MPa for 8 hours. Its tribological properties were tested using a ball-disc friction testing machine. The test results showed that the coefficient of friction was 0.188 and the wear rate was 9.210. -5 mm 3 / Nm.

[0078] As can be seen, compared with pure diamine-type polybenzoxazine resin (poly(PH-ddm)) and unmodified carbon fiber-reinforced diamine-type polybenzoxazine resin composites, carbon fiber-reinforced resin composites with a synergistic reinforcing lubrication composite structure on the surface exhibit lower coefficients of friction and wear rates. Specifically, compared with pure resin, the modified carbon fiber-reinforced diamine-type polybenzoxazine resin composite shows a reduction in coefficient of friction of over 45% and a reduction in wear rate of over 85%. This indicates that carbon fiber-reinforced resin composites with a synergistic reinforcing lubrication composite structure on the surface possess excellent friction-reducing and wear-resistant properties.

[0079] In summary, this invention first modifies carbon fibers by using iron oxide nanoparticles and graphite-phase carbon nitride nanosheets to obtain modified carbon fibers with a multi-scale synergistically enhanced lubrication composite structure formed by the stacking of iron oxide nanoparticles and graphite-phase carbon nitride nanosheets on the surface. The modified carbon fibers can be used to prepare resin composite materials with friction-reducing and wear-resistant effects. These modified carbon fibers can significantly reduce the coefficient of friction and wear rate while maintaining the high mechanical strength and high temperature resistance of the composite material. Furthermore, the modified carbon fibers can be combined with diamine-type polybenzoxazine resin to prepare resin composite materials with friction-reducing and wear-resistant effects. These composite materials can be used to prepare components operating under oil-free, heavy-load, and high-speed conditions, such as high-speed CNC machine tool bearings and heavy-duty sliding bearings, extending component life and improving operational reliability, demonstrating excellent practicality.

[0080] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A modified carbon fiber with a multi-scale synergistically reinforced lubrication composite structure on its surface, characterized in that, The modified carbon fiber is used to construct a multi-scale synergistic lubrication composite structure in situ on the carbon fiber surface. The multi-scale synergistic lubrication composite structure is formed by the stacking of iron oxide nanoparticles and graphite-phase carbon nitride nanosheets. The iron oxide nanoparticles are hematite α-Fe2O3, with a particle size of approximately 50-100 nm; The graphitic carbon nitride nanosheets are distributed in an "upright" state on the surface of the modified carbon fiber.

2. The method for preparing modified carbon fiber according to claim 1, characterized in that, The method includes: (1) The carbon fibers with surface impurities removed were placed in a Tris-HCl buffer solution containing tannic acid (TA) and polyamide-amine (PAMAM) and shaken to react. After the reaction was completed, the carbon fibers were filtered, washed, and dried to obtain activated carbon fibers with TA-PAMAM grafted on the surface. (2) The activated carbon fibers were placed in a mixed solution containing FeCl3·6H2O and surfactant to react. After the reaction was completed, the carbon fibers were washed and dried to obtain carbon fibers with iron oxide grown in situ on the surface. (3) The carbon fibers with iron oxide grown in situ on the surface were immersed in a saturated solution of urea. After immersion, the urea coating was fixed by freeze drying. Then, the carbon fibers were calcined under the protection of high-purity nitrogen. After calcination, modified carbon fibers with a multi-scale synergistic enhancement and lubrication composite structure on the surface were obtained.

3. The method for preparing modified carbon fiber according to claim 2, characterized in that, In step (1), the step of removing surface impurities from carbon fiber includes: soaking carbon fiber in acetone and anhydrous ethanol for 24 hours respectively; The Tris-HCl buffer solution containing tannic acid (TA) and polyamide-amine (PAMAM) has a pH of 8.5, an initial concentration of 0.05 mol / L, a final concentration of tannic acid (TA) of 0.5-2.5 mg / mL, and a final concentration of polyamide-amine (PAMAM) of 1.0-4.5 mg / mL. The polyamide-amine PAMAM includes a G4.0 generation dendritic macromolecule containing 64 amine groups; The ratio of carbon fiber with surface impurities removed to Tris-HCl buffer solution containing tannic acid (TA) and polyamide-amine (PAMAM) was 5 g: 40 mL. The conditions for the shaking reaction are: slow shaking reaction at room temperature for 48 hours.

4. The method for preparing modified carbon fiber according to claim 2, characterized in that, In step (2), the solvent of the mixed solution containing FeCl3·6H2O and surfactant is a mixture of anhydrous ethanol and water, with a volume ratio of anhydrous ethanol to water of 1:1; the amount of the mixed solution used is 50 mL. The surfactants are polypyrrolidone (PVP) and polyethylene glycol (PEG-400); the final concentration ratio of PVP K30 to PEG-400 in the mixture is 10 mg / mL: 5 mg / mL. The final concentration of FeCl3·6H2O is 0.05~0.1mol / L; The reaction conditions are: a solvothermal reaction at 100-125℃ for 24 hours.

5. The method for preparing modified carbon fiber according to claim 2, characterized in that, In step (3), the soaking time is 5 hours; The calcination conditions are as follows: the temperature is increased to 510-530℃ at a rate of 3℃ / min, and the calcination time is 3.5h.

6. The application of the modified carbon fiber with a multi-scale synergistic lubrication composite structure on the surface as described in claim 1 in the preparation of resin composite materials with friction-reducing and wear-resistant effects.

7. A resin composite material with friction-reducing and wear-resistant effects, characterized in that, The resin composite material uses the modified carbon fiber as described in claim 1 as the reinforcement; the matrix of the resin composite material is a diamine-type polybenzoxazine resin, and the structural formula of its monomer is: 。 8. The resin composite material according to claim 7, characterized in that, In the resin composite material, the amount of modified carbon fiber added is 7wt.%~12wt.% of the resin composite material.

9. The application of the resin composite material according to claim 7 in the wear reduction and wear resistance of friction components in the transmission system of mechanical equipment under oil-free, heavy-load, high-speed and other operating conditions.

10. The application according to claim 9, characterized in that, The friction components of the mechanical equipment transmission system include high-speed CNC machine tool bearings and heavy-duty sliding bearings.

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