High density powder modified carbon fiber filament winding method based on ultrasonic spraying

Abstract

The application discloses a high-density powder modified carbon fiber winding forming method based on ultrasonic spraying, which comprises the following steps: firstly, high-density powder slurry is premixed and the viscosity is regulated; under the condition of continuous stirring and stable feeding, high-density functional powder is uniformly attached to the surface of carbon fiber tape or carbon fiber tows to form a film and is integrally formed by winding and solidification through ultrasonic spraying; and a composite winding product formed by tightly combining a high-density powder functional layer and a carbon fiber reinforced layer is obtained in the winding process. The application is suitable for the preparation of winding forming products such as carbon fiber winding pipes, annular parts, cylindrical parts, shells, rotating shafts, rotors, pressure vessels and functional composite components. By selecting different types of high-density functional powder, the carbon fiber composite material after winding forming can further have the characteristics of heat conduction, magnetic conduction, electromagnetic shielding, counterweight, wear resistance and other functional properties on the basis of maintaining high strength and lightweight.

Description

Technical Field

[0001] This invention relates to a carbon fiber winding molding method, and more particularly to a high-density powder-modified carbon fiber winding molding method based on ultrasonic spraying, belonging to the field of carbon fiber composite material winding molding technology. Background Technology

[0002] Carbon fiber filament winding technology, with its advantages of high molding efficiency, controllable fiber orientation, high structural strength, and lightweight products, has been widely used in composite pipe fittings, pressure vessels, drive shafts, ring components, and high-speed rotating components. However, with the continuous expansion of applications for composite materials, structurally reinforced composites formed solely from carbon fibers and resin matrices are no longer sufficient to meet the demands of some fields for thermal conductivity, magnetic permeability, electromagnetic shielding, localized weight distribution, or other functional properties. Therefore, introducing functional powders into the carbon fiber filament winding process, enabling carbon fiber composites to simultaneously possess structural load-bearing capacity and specific functional properties, has become an important development direction for carbon fiber filament winding technology.

[0003] However, a significant density difference exists between the high-density powder and the resin matrix, leading to sedimentation during slurry preparation, storage, transportation, and coating. Simultaneously, high powder content increases slurry viscosity, causing problems such as unstable feeding, nozzle clogging, uneven powder distribution, and insufficient interlayer bonding, making it difficult to uniformly coat narrow carbon fiber ribbons or tows. Furthermore, pre-forming powder adhesive films and then co-winding them with carbon fibers cannot achieve precise control over powder distribution and easily forms obvious interlayer interfaces, affecting the overall performance of the composite material. Therefore, there is an urgent need for a functionalized carbon fiber winding method that can achieve stable feeding, precision spraying, in-situ adhesion, and simultaneous curing of high-density powder slurry during carbon fiber winding.

[0004] A search revealed that patent CN112615450A describes a method for manufacturing a novel magnetic composite motor rotor. This involves mixing permanent magnet powder with epoxy resin and curing it to form a magnetic powder film. Tensile stress is then applied to wind the magnetic powder film and carbon fiber bundles around the outside of the permanent magnet. Finally, a carbon fiber sheath is wound around the formed rotor. Patent CN119642084A proposes a method of pre-impregnating carbon fiber bundles with modified calcium carbonate microspheres containing heat-insulating properties to form fire-resistant fibers, which are then wound with heat-resistant resin to form a fire-resistant high-pressure hydrogen storage cylinder. In actual production, the method of pre-fabricating special functional layers and then winding them easily leads to poor interlayer bonding of the formed fibers and delamination of the formed product. Patent CN118681770A proposes a method of spraying composite material powder using electrostatic spraying. However, conventional electrostatic spraying equipment often relies on pneumatic feeding, and its feeding system is mainly suitable for liquid coatings or low-density powders. For high-density functional powders such as neodymium iron boron and metal powders, the powder is difficult to be stably lifted and transported by airflow due to its own weight and particle agglomeration, which can easily cause pipeline accumulation and material supply interruption, making it difficult to meet the continuous and uniform spraying requirements in the carbon fiber winding process.

[0005] Therefore, it is necessary to propose a method for applying high-density powder to the carbon fiber winding process by ultrasonic spraying, including slurry premixing, stirring and feeding, ultrasonic spraying of slurry, carbon fiber winding and curing, etc., focusing on solving the problem of high-density powder spraying to form wound carbon fiber products. Summary of the Invention

[0006] To address the shortcomings of the aforementioned technologies, this invention provides a high-density powder-modified carbon fiber winding molding method based on ultrasonic spraying, aiming to solve the problem in existing carbon fiber winding molding processes where high-density functional powder is difficult to stably and uniformly introduce onto the surface of carbon fiber ribbons or tows.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is: a high-density powder modified carbon fiber winding molding method based on ultrasonic spraying. The method first premixes and controls the viscosity of high-density powder slurry. Under continuous stirring and stable feeding, high-density functional powder is uniformly attached to the surface of carbon fiber tape or carbon fiber bundle with resin matrix through ultrasonic spraying to form a film and then wound and cured into an integral shape. During the winding process, a composite material winding product with high-density powder functional layer and carbon fiber reinforcement layer tightly bonded is formed.

[0008] Preferably, it includes the following steps: Step S1, raw material premixing: First, add the high-density functional powder and resin matrix to the mixing container at a predetermined volume ratio for premixing. Then, add the coupling agent and stir using mechanical stirring to ensure full wetting and bonding. After premixing evenly, add the curing agent that is compatible with the resin matrix to the system. After adding the curing agent, continue stirring to ensure that the curing agent is evenly dispersed in the powder resin system. Step S2, viscosity control: Add a volatile diluent to the above mixture to control the viscosity of the slurry, and obtain a high-density powder resin slurry with uniform powder dispersion, suitable flowability and suitable for continuous spraying; Step S3, Ultrasonic spraying: The ultrasonic nozzle atomizes the delivered high-density powder resin slurry into tiny droplets and sprays them evenly onto the surface of the moving carbon fiber belt or carbon fiber bundle, so that a continuous liquid or wet high-density powder functional film is formed on its surface. Step S4, Carbon fiber winding: The carbon fiber winding process is carried out simultaneously with the ultrasonic spraying process. The carbon fiber strip or carbon fiber bundle with liquid or wet high-density powder functional adhesive film on the surface is directly wound onto the surface of the winding mandrel, tubular mandrel, annular mandrel, shell mandrel, rotating shaft or other substrate to be wound, forming a winding blank with alternating composite carbon fiber reinforcement layer and high-density powder functional layer. Step S5, Curing and Molding: The winding blank is placed in a curing environment for curing treatment to obtain the composite material winding product.

[0009] Preferably, in step S1, the high-density functional powder includes, but is not limited to, neodymium iron boron magnetic powder, samarium cobalt magnetic powder, iron powder, carbonyl iron powder, ferrite powder, metal powder, thermally conductive ceramic powder, wear-resistant powder, or counterweight powder. The resin matrix is ​​an epoxy resin system suitable for carbon fiber winding molding, which is selected from one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic type epoxy resin, alicyclic epoxy resin, and toughened modified epoxy resin.

[0010] Preferably, in step S1, the volume ratio of the resin matrix to the high-density functional powder is 2 to 4:1; the coupling agent accounts for 0.5% to 3% of the mass of the high-density functional powder; and the mass ratio of the curing agent to the resin matrix is ​​0.6 to 1.2:1. The mechanical stirring speed is 300-800 r / min, and the stirring time is 5-20 min.

[0011] Preferably, in step S2, the volatile diluent is selected from acetone, toluene, ethyl acetate, and anhydrous ethanol, and its addition amount is 5% to 15% of the total mass of the slurry system; mechanical stirring controls the apparent viscosity of the slurry to a range not exceeding 150 mPa·s. Preferably, in step S3, a stirrer is set at the front end of the feeding process to continuously stir at 200-500 r / min. While the slurry is continuously stirred, high-density powder slurry is extracted from the storage container through a continuous feeding method and transported to the ultrasonic nozzle through a hose.

[0012] Preferably, in step S3, during spraying, the spraying height of the ultrasonic nozzle is 10-15 mm, and the continuous feeding speed is 5-10 ml / min.

[0013] Preferably, before proceeding to step S4, the sprayed carbon fiber strip or carbon fiber bundle is first subjected to a low-temperature heat treatment at 40-60°C.

[0014] Preferably, in step S5, the pre-curing stage is maintained at 40-80℃ for 10-60 minutes; the main curing agent stage is first maintained at 60-100℃ for 60-90 minutes, and then maintained at 120℃-160℃ for 90-120 minutes.

[0015] Preferably, in step S5, after curing, the composite material winding product is cooled to room temperature in the oven or under controlled conditions, and demolded, trimmed, end-faced, surface treated or otherwise post-treated as required.

[0016] This invention involves premixing high-density functional powder with a resin matrix to form a slurry. During the winding process of carbon fiber ribbons or tows, the high-density powder slurry is then ultrasonically sprayed onto the surface of the carbon fiber ribbons or tows in situ. Following winding and curing, a carbon fiber composite material product with a specific functional layer is formed. This invention is applicable to the preparation of wound-molded products such as carbon fiber pipes, ring-shaped parts, cylindrical parts, shells, shafts, rotors, pressure vessels, and functional composite components. By selecting different types of high-density functional powders, the wound carbon fiber composite material can maintain its high strength and lightweight properties while further acquiring thermal conductivity, magnetic permeability, electromagnetic shielding, weight distribution, wear resistance, or other functional properties. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the device of the present invention.

[0018] Figure 2 This is a process flow diagram of the present invention.

[0019] Figure 3 The graph shows the mechanical property test results of the sample prepared in Example 1 of this invention; Figure 3 a is the tensile properties diagram of the prepared sample. Figure 3 b is the shear performance diagram of the prepared sample.

[0020] Figure 4 This is a graph showing the magnetic property test results of the sample prepared in Example 1 of the present invention; Figure 4 a represents the maximum remanence of the prepared sample. Figure 4 b is the demagnetization curve of the prepared sample.

[0021] Figure 5 This is a microscopic image of the sample prepared in Example 1 of the present invention under a confocal microscope. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0023] Because high-density powders are prone to settling, and high powder content leads to increased slurry viscosity, existing processes are prone to problems such as uneven spraying, difficulty in precisely controlling the spraying area and thickness, nozzle clogging, and insufficient bonding between the functional powder layer and the carbon fiber layer. This invention achieves functionalized integrated molding of carbon fiber wound products through slurry premixing and viscosity control, continuous stirring to prevent settling, continuous feeding, ultrasonic spraying for film formation, and simultaneous winding and curing. This gives the products properties such as thermal conductivity, magnetic conductivity, electromagnetic shielding, or counterweight.

[0024] like Figure 2 As shown, this invention provides a method for high-density powder-modified carbon fiber winding based on ultrasonic spraying. The core of this method is the integrated molding process of high-density powder slurry premixing and viscosity control, continuous stirring of the high-density powder slurry to prevent sedimentation, stable feeding via a peristaltic pump, ultrasonic spraying of a film onto the surface of carbon fiber strips or carbon fiber bundles, and winding and curing. This allows high-density functional powder to be uniformly attached to the surface of the carbon fiber strips or carbon fiber bundles along with the resin matrix, forming a composite material winding product with a tightly bonded high-density powder functional layer and a carbon fiber reinforcing layer during the winding process.

[0025] The preferred material storage and stirring unit is used to continuously stir the high-density powder slurry to prevent powder sedimentation; the peristaltic pump is used to stably and continuously deliver the slurry to the ultrasonic nozzle; the ultrasonic nozzle is set at the front end of the carbon fiber belt or carbon fiber bundle entering the winding mold, and is used to uniformly spray the slurry onto the carbon fiber surface before winding to form a continuous functional powder film.

[0026] High-density powder slurry includes: selected high-density functional powder, resin matrix, curing agent, coupling agent, and volatile diluent. High-density functional powder refers to powder materials with a density higher than the resin matrix that can impart specific functions to carbon fiber wound products, including but not limited to neodymium iron boron magnetic powder, samarium cobalt magnetic powder, iron powder, carbonyl iron powder, ferrite powder, metal powder, thermally conductive ceramic powder, wear-resistant powder, or weighting powder.

[0027] The resin matrix is ​​preferably an epoxy resin system suitable for carbon fiber winding molding, including one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic type epoxy resin, alicyclic epoxy resin, and toughened modified epoxy resin, preferably a low viscosity, medium temperature resistance, and high toughness epoxy resin system; the curing agent is an essential component in the epoxy resin curing process, and the specific model should correspond to the selected epoxy resin.

[0028] Coupling agents are added as a separate reagent to connect inorganic powders and organic epoxy resins, improve the interfacial bonding between the powder and resin, and simultaneously improve powder dispersion and reduce agglomeration. The specific type of coupling agent should be determined by the type of powder incorporated into the slurry; for example, silane coupling agents (KH550, KH560, etc.) are preferred for metal powders.

[0029] First, high-density functional powder and resin matrix are premixed in a mixing container at a predetermined mass ratio. Preferably, the volume ratio of resin matrix to high-density functional powder is 2–4:1. Then, a coupling agent of 0.5%–3% of the mass of the high-density functional powder is added, and the mixture is mechanically stirred at 300–800 rpm for 5–20 minutes to ensure thorough wetting and bonding of the high-density functional powder, coupling agent, and resin matrix. After uniform premixing of the high-density functional powder, coupling agent, and resin matrix, a curing agent compatible with the resin matrix is ​​added to the system. After adding the curing agent, stirring is continued at 300 rpm for 5 minutes to ensure uniform dispersion of the curing agent in the powdered resin system.

[0030] "Matching" refers to a specific combination selected by the manufacturer based on the chemical structure of the resin matrix and application requirements, through formulation development and field testing. This combination ensures normal curing reaction and system stability, enabling the product to achieve its preset performance. Epoxy resin molecules contain active groups such as epoxy and hydroxyl groups. When existing alone, the molecules cannot form a three-dimensional network structure. After mixing the curing agent in a certain proportion, the curing agent reacts chemically with the active groups, the molecular chains crosslink, and the system gradually transforms from a liquid state into a solid thermosetting material.

[0031] To ensure the slurry meets the atomization requirements of ultrasonic spraying, a volatile diluent is added to the above-mentioned mixture to adjust the viscosity of the slurry. Preferably, the volatile diluent is acetone, and its addition amount is 5% to 15% of the total mass of the slurry system. Through diluent adjustment and mechanical stirring, the high-density powder slurry is brought to a flow state suitable for ultrasonic spraying, preferably with the apparent viscosity of the slurry controlled within a range not exceeding 150 mPa·s. This yields a high-density powder resin slurry with uniform powder dispersion, suitable flowability, and suitable for continuous spraying.

[0032] Because the density of high-density functional powders is typically higher than that of the resin matrix, if the slurry is left to stand for an extended period, the powder is prone to settling, leading to uneven slurry composition, blockage of delivery pipelines, and nozzle clogging. Therefore, if... Figure 1 As shown, the present invention has a stirrer installed at the front end of the feeding line to continuously stir at 200-500 r / min, so that the slurry is always in a uniform suspension state before entering the feeding pipeline.

[0033] During the mixing process, the stirring paddle remains below the slurry surface to avoid introducing a large number of air bubbles. When the slurry viscosity, powder content, powder type, or spraying time changes, the stirring speed can be adjusted accordingly to ensure that the high-density functional powder remains uniformly dispersed in the resin system. Continuous stirring maintains the stable suspension state of the high-density powder slurry, preventing the powder from settling before storage, feeding, and spraying.

[0034] While the slurry is continuously stirred, a continuous feeding device, such as a peristaltic pump or diaphragm pump, is used to continuously pressurize and extract high-density powder slurry from the storage container, and then deliver the slurry to the ultrasonic nozzle through a hose. The feeding speed of the continuous feeding device is adjusted according to the width of the carbon fiber tape or carbon fiber bundle, the winding speed, the thickness of the target powder functional layer, and the spraying width.

[0035] Preferably, the feeding rate of the continuous feeding device is 5-10 ml / min. By adjusting the flow rate of the device, the amount of slurry supplied at the ultrasonic nozzle is matched with the movement speed of the carbon fiber belt or carbon fiber bundle, avoiding insufficient feeding which would lead to discontinuity of the powder functional layer, and also avoiding excessive feeding which would cause slurry accumulation, sagging, or material waste.

[0036] The ultrasonic nozzle is placed at the front end of the winding mold or mandrel of the carbon fiber winding equipment, between the winding mold and the guide roller. Furthermore, the position of the ultrasonic nozzle can be adjusted using a dual-motor module or other equivalent motion control method, allowing the nozzle to move along the width and vertical directions of the carbon fiber strip. Vertical adjustment can change the spraying height to adapt to different slurry viscosities, feed rates, and target spraying widths; small reciprocating movements in the width direction can ensure that the central spraying area covers the full width of the carbon fiber strip or bundle, improving coating uniformity and reducing slurry waste. By proposing a process concept that allows for online adjustment of nozzle position and spraying parameters, the ultrasonic spraying process can be adapted in real time according to the carbon fiber width, winding speed, and the film-forming state of the functional powder adhesive.

[0037] Before entering the winding mold or mandrel, the carbon fiber tape or tow passes through an ultrasonic spraying area. The ultrasonic nozzle atomizes high-density powdered resin slurry, delivered by a peristaltic pump, into tiny droplets and evenly sprays them onto the surface of the moving carbon fiber tape or tow, forming a continuous liquid or wet high-density powder functional adhesive film. The ultrasonic spraying process is synchronized with the carbon fiber winding process; under the subsequent winding pressure and tension, the high-density powder functional adhesive film fully adheres to the carbon fiber reinforcement layer.

[0038] During spraying, the spraying height of the ultrasonic nozzle is 10-15mm, thereby ensuring that the high-density powder functional adhesive film is continuously, uniformly and completely distributed on the surface of carbon fiber tape or carbon fiber bundle.

[0039] Depending on the needs, the ultrasonic nozzle can perform small-amplitude reciprocating spraying along the width of the carbon fiber strip, or the high powder concentration area in the spraying center can be covered to cover the surface of the carbon fiber strip by adjusting the spraying height, feeding speed, and carbon fiber strip running speed. For wound products that require local functional load control, the thickness of the high-density powder functional adhesive film at different axial, circumferential, or interlayer positions can also be adjusted by changing the peristaltic pump feeding speed, spraying frequency, or spraying start / stop.

[0040] Carbon fiber ribbons or tows with a liquid or wet high-density powder functional adhesive film on their surface are directly wound onto the surface of a winding mandrel, tubular mandrel, annular mandrel, shell mandrel, rotating shaft, or other substrate to be wound. During the winding process, the carbon fiber ribbons or tows are continuously laid under a set tension. The high-density powder functional adhesive film is sandwiched between adjacent carbon fiber layers, or between a carbon fiber layer and the substrate to be wound, and further spreads and wets under interlayer pressure, forming a wound preform with alternating carbon fiber reinforcement layers and high-density powder functional layers. Furthermore, a volatile heating zone is set between the ultrasonic spraying area and the winding forming area, so that the sprayed carbon fiber ribbons or tows are subjected to low-temperature heating treatment of 40-60°C before entering the winding process, so as to promote the early evaporation of volatile diluents such as acetone and reduce their adverse effects on subsequent winding, curing, and interlayer bonding performance.

[0041] The completed composite preform is placed in a curing environment for curing treatment, which cross-links and cures the resin system in the high-density powder functional film, and forms a stable bond between the carbon fiber layer and the high-density powder functional layer.

[0042] The pre-curing stage involves holding the resin at 40–80°C for 10–60 minutes to further expel volatile diluents and improve the initial bond strength of the slurry. The main curing stage involves first holding the resin at 60–100°C for 60–90 minutes, followed by holding it at 120–160°C for 90–120 minutes. This main curing stage is used to complete the main cross-linking reaction of the resin system and should be consistent with the curing conditions of the selected resin system.

[0043] After curing, the composite material wound product is cooled to room temperature in the oven or under controlled conditions, and demolded, outer circle trimmed, end face machined, surface treated or other post-treatments are performed according to design requirements.

[0044] Other post-processing includes, but is not limited to, cleaning, deburring, grinding and polishing, secondary curing, stress relief treatment, pore sealing, surface protective coating, insulating coating, wear-resistant coating, dynamic balancing correction, pre-assembly processing, and functional performance testing; when the high-density functional powder is magnetic powder, it may also include magnetization, demagnetization, or magnetic performance testing; when the high-density functional powder is thermally conductive, thermally insulating, magnetically conductive, or electromagnetically shielding powder, it may also include testing of the corresponding thermal conductivity, thermal insulation, magnetic permeability, or electromagnetic shielding performance.

[0045] Example 1

[0046] Preparation of a carbon fiber composite rotor with magnetic properties: Micron-sized NdFeB magnetic powder was selected as the high-density functional powder, and epoxy resin suitable for carbon fiber winding was selected as the resin matrix. 50g of NdFeB magnetic powder and 50g of epoxy resin were added to a mixing container, followed by the addition of 1g of silane coupling agent KH550. The mixture was stirred at 500 rpm for 10 minutes to ensure thorough impregnation and mixing of the NdFeB magnetic powder, coupling agent, and epoxy resin. Then, 50g of a curing agent compatible with the epoxy resin was added, and stirring continued at 300 rpm for 5 minutes. Finally, 10g of acetone was added as a volatile diluent, and stirring continued until the system was homogeneous, yielding a NdFeB magnetic powder resin slurry suitable for ultrasonic spraying.

[0047] The prepared slurry was placed in a storage container and continuously stirred by a stirrer during the spraying process to prevent the NdFeB magnetic powder from settling. A peristaltic pump was used to continuously deliver the slurry to the ultrasonic nozzle. With a fiber belt width of 8 mm, the distance between the ultrasonic nozzle and the surface of the carbon fiber belt was adjusted to 10 mm, and the peristaltic pump feed rate was 3.5 ml / min. The carbon fiber belt passed through the ultrasonic spraying area before entering the shaft winding area. The NdFeB magnetic powder resin slurry was uniformly sprayed onto the surface of the carbon fiber belt after ultrasonic atomization, forming a continuous wet magnetic powder film.

[0048] Carbon fiber strips with a magnetic powder functional adhesive film on their surface are directly wound onto the surface of a metal shaft or rotor core. During the winding process, the magnetic powder functional adhesive film is held between adjacent carbon fiber layers under tension and interlayer pressure, and fully adheres to the carbon fiber reinforcement layer. Depending on the rotor strength requirements, one or more layers of non-magnetic powder carbon fiber reinforcement layers can be wound on the outside of the magnetic powder functional adhesive film layer to improve the tensile strength and high-speed rotational stability of the composite rotor.

[0049] After winding, the composite rotor blank is placed in a curing environment for treatment. First, it is pre-cured at 60℃ for 30 minutes, then main cured at 100-120℃ for 1 hour, and finally post-cured at 80℃ for 30 minutes. After curing, it is cooled to room temperature, and then the outer circle is trimmed, the end face is machined, and magnetization is performed as needed to obtain a carbon fiber composite rotor with magnetic properties.

[0050] The permanent magnet powder / carbon fiber composite material samples prepared using the above process were tested for mechanical and magnetic properties, demonstrating that this process can produce composite material products that possess both structural load-bearing capacity and magnetic properties. Details are as follows: In terms of mechanical properties, three winding tensions of 20N, 35N, and 50N were used to prepare ring-shaped samples of magnetic powder composite materials. Figure 3 'a' represents the tensile strength of the prepared specimen. The horizontal axis represents different fiber specimens prepared under different winding tension regimes, including pure carbon fiber specimens and magnetic powder doped specimens. The vertical axis represents the tensile strength value of the specimen.

[0051] Test results show that the tensile strength of the sample coated with magnetic powder is lower than that of the pure carbon fiber wound sample. However, when the winding tension reaches 35N or 50N, the tensile strength of the magnetic powder-doped sample can reach 1602.32MPa and 1901.51MPa, respectively. Compared with the 2076.03MPa and 2556.21MPa of the pure carbon fiber sample, it can still maintain about 74%~77% of the tensile strength. This strength is far superior to that of permanent magnet materials used in general motor rotors.

[0052] Figure 3 b represents the shear strength of the prepared sample. The horizontal axis represents different fiber samples prepared under different winding tension regimes, including pure carbon fiber samples and magnetic powder doped samples. The vertical axis represents the shear strength value of the sample.

[0053] Testing revealed that the shear strength of the magnetic powder-coated sample was almost identical to that of the pure carbon fiber sample at a winding tension of 50 N, at 56.59 MPa and 56.40 MPa respectively. However, under low-tension winding conditions, due to the "pinning" effect of the magnetic powder on the interlayer of the carbon fiber sample, the shear strength of the magnetic powder-doped sample reached 45.55 MPa at a winding tension of 20 N, which was higher than the 28.45 MPa of the pure carbon fiber sample. As the fiber content in the composite material sample increased with increasing winding tension, its shear strength was also enhanced. Therefore, at a combined winding tension of 35 N, the shear strength of the pure carbon fiber sample was 53.95 MPa, slightly higher than the 48.85 MPa of the magnetic powder-doped sample. This indicates that the influence of magnetic powder on the mechanical properties of the composite material produced by this process gradually weakens with increasing tension. The mechanical properties of the resulting magnetic composite fiber sample are slightly inferior to those of carbon fiber composites, but significantly superior to those of traditional magnetic materials.

[0054] Figure 4 'a' represents the maximum remanence of the samples under different winding tension regimes. Magnetic property testing showed that the maximum remanence of the samples wound using this process was 97.9 mT at a winding tension of 50 N, an increase of approximately 43% from 68.4 mT at a winding tension of 20 N. Subsequently, with continuously increasing winding tension, the resin between the fibers was squeezed out, carrying away the magnetic powder. Simultaneously, the magnetic powder was pressed into the fiber interior, weakening the continuous magnetic layer thickness, and the maximum remanence decreased to 74.1 mT, approximately 75% of that at a winding tension of 50 N, but still exhibiting significant magnetism.

[0055] Figure 4 b shows the demagnetization curve as the winding tension increases from 20 N to 80 N. Under different winding tensions, the coercivity and energy product of the prepared samples also change. As shown in the figure, as the winding tension increases from 20 N to 50 N, the intrinsic coercivity increases from approximately 310 KA / m to approximately 400 KA / m. The simultaneous increase in intrinsic coercivity and maximum remanence implies an increase in the maximum energy product. When the winding tension increases from 50 N to 80 N, the intrinsic coercivity decreases slightly but remains around 350 KA / m, indicating that the sample possesses very significant magnetic properties.

[0056] The sample of the formed sprayed magnetic powder was observed after polishing. Figure 5 The figures show the microstructure of the interlayers of samples prepared at different observation scales. The black continuous filamentous areas represent carbon fibers, while the white highlighted blocky areas represent incorporated magnetic powder particles or magnetic powder-rich regions. As can be seen, the carbon fibers are arranged in a relatively regular orientation along the winding direction, indicating that the continuity and orientation of the carbon fiber bundles were not significantly disrupted during ultrasonic spraying and subsequent winding and curing. The magnetic powder is mainly distributed on the surface of the carbon fiber bundles and in the interfiber gaps, and is embedded in the carbon fiber interlayers along with the resin matrix, indicating that the magnetic powder film formed by spraying can adhere to and wet the carbon fiber layers under winding pressure. From the local morphology, the white magnetic powder areas are not completely detached from the carbon fiber layers, but rather form contact bonds with the surrounding resin matrix and carbon fibers, indicating that this process can achieve integrated composite of the magnetic powder functional layer and the carbon fiber reinforcing layer. At higher magnification, some magnetic powder was dispersed near the fiber in the form of fine particles or local agglomerations. No large-area continuous delamination or obvious through cracks were observed, indicating that the magnetic powder slurry can adhere well to the carbon fiber surface after ultrasonic spraying and form a relatively stable interlayer structure after curing.

[0057] Meanwhile, a small number of relatively large white magnetic powder enrichment areas can still be observed in the images, indicating that there is a certain degree of local aggregation of high-density magnetic powder in the resin slurry. This phenomenon further illustrates the necessity of setting up slurry viscosity control, continuous stirring to prevent sedimentation, stable material supply by peristaltic pump, and online adjustment of spraying parameters in this process. Overall, the two micrographs demonstrate that after adopting the ultrasonic spraying-winding curing process described in this invention, the magnetic powder can enter the carbon fiber interlayer along with the resin matrix and adhere to the fiber surface, which is beneficial for forming a composite structure that combines the load-bearing function of carbon fiber and the functional function of magnetic powder.

[0058] Example 2

[0059] Preparation of thermally conductive carbon fiber wound tubes or sleeves: Micron-sized aluminum nitride powder was selected as the high-density thermally conductive powder, and epoxy resin suitable for winding molding was selected as the resin matrix. Aluminum nitride powder and epoxy resin were added to a mixing container at a 1:1 mass ratio, followed by the addition of 3% (by mass) of silane coupling agent KH550 from the aluminum nitride powder. The mixture was stirred at 400 rpm for 5 minutes to ensure thorough mixing. Then, a curing agent compatible with the epoxy resin was added, and 10% (by mass) of acetone was added to adjust the viscosity. After thorough stirring, a thermally conductive powder-resin slurry suitable for ultrasonic spraying was obtained.

[0060] The aforementioned thermally conductive powder resin slurry was placed in a storage container and continuously stirred during the spraying process to maintain the aluminum nitride powder in a uniform suspension. A peristaltic pump was used to deliver the slurry to the ultrasonic nozzle, with the pump feed rate set to 7.5 ml / min. With a carbon fiber bundle width of 8 mm, the distance between the ultrasonic nozzle and the carbon fiber tape surface was set to 10 mm. Before entering the tubular or sleeve mandrel, the carbon fiber tape passed through the ultrasonic spraying area, ensuring the thermally conductive powder resin slurry was uniformly sprayed onto the carbon fiber tape surface, forming a continuous wet thermally conductive functional film.

[0061] Carbon fiber tape with a thermally conductive adhesive film on its surface is continuously wound onto the surface of a tubular or sleeve mandrel. During the winding process, the thermally conductive adhesive film is held between adjacent carbon fiber layers and tightly adheres to the carbon fiber layers under winding tension. Depending on the product's requirements, a thermally conductive powder functional layer can be provided in the inner or middle layer, or a carbon fiber reinforcement layer without thermally conductive powder can be wound on the outer side to balance thermal conductivity and structural strength.

[0062] After winding, the preform is placed in a curing environment for curing. First, it is pre-cured at 50°C for 30 minutes, then the main curing is carried out according to the curing conditions of the selected epoxy resin system, and finally post-curing is carried out at 70°C for 30 minutes. After curing, it is cooled to room temperature and then demolded, the end face is trimmed or surface treated to obtain a carbon fiber wound tube or sleeve with thermal conductivity.

[0063] This embodiment primarily illustrates the applicability of the method of the present invention to high-density functional powders with thermal conductivity or thermal insulation properties. From the molding process and structural characteristics, the product obtained in this embodiment shows that the thermally conductive or thermally insulating powder can be uniformly adhered to the surface of carbon fiber tape or carbon fiber bundle through resin slurry, and simultaneously wound and cured with the carbon fibers, forming a functional powder film distributed between the carbon fiber layers. Compared with direct mixing into the resin or subsequent coating, this method can reduce high-density powder sedimentation and local accumulation, and improve the continuity of powder distribution and interlayer bonding stability in the carbon fiber winding layer. For thermally conductive powders, this structure facilitates the formation of thermally conductive pathways between the carbon fiber layers, improving the product's heat conduction and heat dissipation capabilities; for thermally insulating powders, a functional layer with thermal resistance can be formed between the layers, reducing heat transfer. Therefore, this embodiment demonstrates the versatility of the present invention in the functional molding of carbon fiber wound products, enabling products to maintain the high strength and lightweight advantages of carbon fiber while further acquiring additional functions such as thermal conductivity or thermal insulation.

[0064] Example 3

[0065] Preparation of carbon fiber wound sleeves with magnetic permeability and electromagnetic shielding functions: Carbonyl iron powder was selected as the high-density magnetic permeable powder, and medium-temperature resistant, high-toughness epoxy resin was selected as the resin matrix. 50g of carbonyl iron powder, 50g of epoxy resin, and 1g of silane coupling agent KH550 were weighed and added to a mixing container. The mixture was stirred at 500 rpm for 10 minutes using a mechanical stirrer to ensure thorough wetting and mixing of the carbonyl iron powder, coupling agent, and epoxy resin. Then, 50g of curing agent compatible with the epoxy resin was added, and stirring continued at 300 rpm for 5 minutes. Finally, 10g of acetone was added as a volatile diluent, and stirring continued until the system was homogeneous, yielding a carbonyl iron powder / epoxy resin slurry suitable for ultrasonic spraying.

[0066] The slurry was placed in a storage container and continuously stirred at 280 rpm during the spraying process to keep the carbonyl iron powder in a uniform suspension in the resin system. Then, a peristaltic pump was used to deliver the slurry through a hose to the ultrasonic nozzle, with the pump feed rate set to 3.5 ml / min.

[0067] An 8mm wide carbon fiber strip is introduced into the winding system, passing through an ultrasonic spraying area before entering the sleeve mandrel. The distance between the ultrasonic nozzle and the surface of the carbon fiber strip is adjusted to 10mm, and the nozzle is made to reciprocate ±4mm along the width direction of the carbon fiber strip, so that the carbonyl iron powder slurry is evenly sprayed onto the surface of the moving carbon fiber strip, forming a continuous wet magnetic conductive functional film.

[0068] The coated carbon fiber tape is first passed through a pre-evaporation heating zone at 50°C to allow acetone to partially evaporate before winding. Then, it is directly wound onto the surface of a sleeve mandrel with an outer diameter of 40 mm and a length of 120 mm. The winding tension is set to 50 N, and a total of 10 layers are wound. The first and second layers are carbon fiber reinforcement layers without coating, the third to eighth layers are carbon fiber composite layers with carbonyl iron powder functional adhesive film, and the ninth and tenth layers are outer carbon fiber reinforcement layers.

[0069] After winding, the sleeve blank is placed in a curing environment for treatment. First, it is pre-cured at 60℃ for 30 minutes, then main cured at 110℃ for 60 minutes, and finally post-cured at 80℃ for 30 minutes. After curing, it is cooled to room temperature, demolded, end face trimmed, outer circle ground, and surface cleaned to obtain a carbon fiber wound sleeve with magnetic conductivity and electromagnetic shielding functions.

[0070] This invention achieves uniform adhesion of high-density powder to the surface of carbon fiber tapes or tows by premixing high-density powder with resin, viscosity control, continuous stirring to prevent sedimentation, peristaltic pump feeding, ultrasonic spraying for film formation, and simultaneous winding and curing. This process integrates the high-density powder with the carbon fiber reinforcement layer. This method improves upon issues such as easy sedimentation of high-density powder, uneven spraying, nozzle clogging, and weak interlayer bonding. While maintaining the high strength and lightweight advantages of carbon fiber products, it also endows them with functional properties such as thermal conductivity, magnetic permeability, magnetism, electromagnetic shielding, wear resistance, or weight distribution.

[0071] The above embodiments are not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the technical solution of the present invention are also within the protection scope of the present invention.

Claims

1. A method for high-density powder-modified carbon fiber winding based on ultrasonic spraying, characterized in that: The method first premixes and adjusts the viscosity of high-density powder slurry. Under continuous stirring and stable feeding, high-density functional powder is uniformly attached to the surface of carbon fiber tape or carbon fiber bundle with resin matrix through ultrasonic spraying to form a film and then wound and cured into an integral shape. During the winding process, a composite material winding product with high-density powder functional layer and carbon fiber reinforcement layer tightly bonded together is formed.

2. The method for high-density powder-modified carbon fiber winding based on ultrasonic spraying according to claim 1, characterized in that: Includes the following steps: Step S1, raw material premixing: First, add the high-density functional powder and resin matrix to the mixing container at a predetermined volume ratio for premixing. Then, add the coupling agent and stir using mechanical stirring to ensure full wetting and bonding. After premixing evenly, add the curing agent that is compatible with the resin matrix to the system. After adding the curing agent, continue stirring to ensure that the curing agent is evenly dispersed in the powder resin system. Step S2, viscosity control: Add a volatile diluent to the above mixture to control the viscosity of the slurry, and obtain a high-density powder resin slurry with uniform powder dispersion, suitable flowability and suitable for continuous spraying; Step S3, Ultrasonic spraying: The ultrasonic nozzle atomizes the delivered high-density powder resin slurry into tiny droplets and sprays them evenly onto the surface of the moving carbon fiber belt or carbon fiber bundle, so that a continuous liquid or wet high-density powder functional film is formed on its surface. Step S4, Carbon fiber winding: The carbon fiber winding process is carried out simultaneously with the ultrasonic spraying process. The carbon fiber strip or carbon fiber bundle with liquid or wet high-density powder functional adhesive film on the surface is directly wound onto the surface of the winding mandrel, tubular mandrel, annular mandrel, shell mandrel, rotating shaft or other substrate to be wound, forming a winding blank with alternating composite carbon fiber reinforcement layer and high-density powder functional layer. Step S5, Curing and Molding: The winding blank is placed in a curing environment for curing treatment to obtain the composite material winding product.

3. The method for high-density powder-modified carbon fiber winding based on ultrasonic spraying according to claim 2, characterized in that: In step S1, the high-density functional powder includes, but is not limited to, neodymium iron boron magnetic powder, samarium cobalt magnetic powder, iron powder, carbonyl iron powder, ferrite powder, metal powder, thermally conductive ceramic powder, wear-resistant powder, or counterweight powder. The resin matrix is ​​an epoxy resin system suitable for carbon fiber winding molding, which is selected from one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic type epoxy resin, alicyclic epoxy resin, and toughened modified epoxy resin.

4. The method for high-density powder-modified carbon fiber winding based on ultrasonic spraying according to claim 2, characterized in that: In step S1, the volume ratio of resin matrix to high-density functional powder is 2-4:1; the coupling agent accounts for 0.5%-3% of the mass of high-density functional powder; and the mass ratio of curing agent to resin matrix is ​​0.6-1.2:

1. The mechanical stirring speed is 300-800 r / min, and the stirring time is 5-20 min.

5. The method for high-density powder-modified carbon fiber winding based on ultrasonic spraying according to claim 2, characterized in that: In step S2, the volatile diluent is selected from acetone, toluene, ethyl acetate, and anhydrous ethanol, and its addition amount is 5% to 15% of the total mass of the slurry system; mechanical stirring controls the apparent viscosity of the slurry to a range not exceeding 150 mPa·s.

6. The method for high-density powder-modified carbon fiber winding based on ultrasonic spraying according to claim 2, characterized in that: In step S3, a stirrer is set at the front end of the feeding process to continuously stir at 200-500 r / min. While the slurry is being continuously stirred, high-density powder slurry is extracted from the storage container through a continuous feeding method and transported to the ultrasonic nozzle through a hose.

7. The method for high-density powder-modified carbon fiber winding based on ultrasonic spraying according to claim 6, characterized in that: In step S3, during spraying, the spraying height of the ultrasonic nozzle is 10-15 mm, and the continuous feeding rate is 5-10 ml / min.

8. The method for high-density powder-modified carbon fiber winding based on ultrasonic spraying according to claim 2, characterized in that: Before proceeding to step S4, the sprayed carbon fiber tape or carbon fiber bundle undergoes a low-temperature heat treatment at 40–60°C.

9. The method for high-density powder-modified carbon fiber winding based on ultrasonic spraying according to claim 2, characterized in that: In step S5, the pre-curing stage is maintained at 40-80℃ for 10-60 minutes; the main curing agent stage is first maintained at 60-100℃ for 60-90 minutes, and then maintained at 120℃-160℃ for 90-120 minutes.

10. The method for high-density powder-modified carbon fiber winding based on ultrasonic spraying according to claim 1, characterized in that: In step S5, after curing is completed, the composite material winding product is cooled to room temperature in the furnace or under controlled conditions, and demolding, outer circle trimming, end face processing, surface treatment or other post-treatments are performed as required.

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