Method of laying up a multi-layer fabric to enhance interlaminar bond strength of carbon fibre material

Abstract

The application relates to the technical field of high-performance composite material preparation, and discloses a multilayer fabric laying method for improving interlayer bonding strength of carbon fiber material, which comprises the following steps: step one, selecting carbon nanotubes or graphene sheets as nanoparticles, performing chemical oxidation treatment to introduce functional groups, and performing functionalization treatment by using a silane coupling agent; step two, mixing the functionalized nanoparticles and epoxy resin in a high-shear mixing device to form a uniform nano-reinforced resin; step three, using a three-dimensional braiding machine to braid carbon fibers according to a predetermined three-dimensional structure mode, and monitoring fiber tension and braiding density in real time during the braiding process. By using the nano-particle reinforced composite material, performing chemical oxidation and coupling agent functionalization treatment, the interfacial adhesion between the carbon fibers and the epoxy resin is improved, the functional groups can form stronger chemical bonds with the resin, the interlayer shear strength of the composite material is improved, and the overall structural integrity and durability of the material are enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-performance composite material preparation, specifically a multi-layer fabric laying method for improving the interlaminar bonding strength of carbon fiber materials. BACKGROUND

[0002] In modern industry, especially in the fields of aerospace, automotive manufacturing, and sports equipment, there is a growing demand for high-performance composite materials. These materials need to have excellent mechanical strength, heat resistance, and excellent structural integrity to meet the stringent application requirements. Carbon fiber composites are widely used in these fields due to their lightweight and high-strength characteristics, and their performance advantages are of great significance for improving product performance and energy efficiency.

[0003] In the prior art, the preparation of carbon fiber composites mainly relies on traditional resin-based composite processes such as hand lay-up, vacuum bag compression, and resin transfer molding (RTM). In these methods, the combination of carbon fibers and resin is usually achieved through simple mechanical mixing, while the curing process of the resin is often carried out under relatively simple conditions, such as a single curing temperature and pressure.

[0004] However, the existing technology has limitations in the interfacial adhesion between carbon fibers and resin, which directly affects the interlaminar shear strength of the composite material. Due to the insufficient interfacial adhesion, the composite material is prone to interlaminar separation when subjected to tensile or shear forces, resulting in weakening of the overall structure. This problem limits the application of composite materials in situations that require high mechanical loads or in high-temperature environments, affecting the widespread application and long-term reliability of the material. SUMMARY

[0005] To overcome the shortcomings of the prior art, the present application provides a multi-layer fabric laying method for improving the interlaminar bonding strength of carbon fiber materials, which solves the problem of insufficient interlaminar shear strength of composite materials in the prior art.

[0006] To achieve the above purpose, the present application is implemented by the following technical scheme: a multi-layer fabric laying method for improving the interlaminar bonding strength of carbon fiber materials, comprising the following steps:

[0007] Step one, select carbon nanotubes or graphene sheets as nanoparticles, perform chemical oxidation treatment to introduce functional groups, and perform functionalization treatment using silane coupling agents;

[0008] Step two, mix the functionalized nanoparticles with epoxy resin in a high-shear mixing device to form a uniform nano-reinforced resin;

[0009] Step three, use a three-dimensional braiding machine to braid carbon fibers according to a predetermined three-dimensional structure pattern, and monitor the fiber tension and braiding density in real time during the braiding process;

[0010] Step four, the nano-reinforced resin is injected into the pre-woven carbon fiber structure under controlled temperature and pressure conditions by resin transfer molding process, and the curing process is carried out at multiple temperature and pressure stages.

[0011] Preferably, the chemical oxidation process is carried out at a temperature controlled at 40-60°C, and the processing time is 1-3 hours.

[0012] Preferably, the silane coupling agent is 3-aminopropyl triethoxysilane, the mass ratio of nano-particles is 1:10, and the functionalization processing time is controlled at 2-4 hours.

[0013] Preferably, the mixing of nano-particles and epoxy resin is carried out by high-energy ball milling, the ball milling time is 30-60 minutes, and the ball milling speed is set at 500-800 rpm.

[0014] Preferably, the nano-reinforced resin mixture is immediately subjected to vacuum degassing treatment for at least 15 minutes after mixing, and the vacuum pressure is-0.1 MPa.

[0015] Preferably, the three-dimensional braiding machine is equipped with a microprocessor-controlled automatic tension adjustment system to ensure the consistency of fiber tension during the braiding process.

[0016] Preferably, the braiding parameters include fiber tension setting at 200-500 Newton, braiding density is not less than 15 strands of fiber per square centimeter, and layer thickness is adjusted according to the design requirements of the final structure component.

[0017] Preferably, the resin transfer molding process includes a low-pressure pre-injection stage and a high-pressure full-injection stage to ensure complete resin infiltration and defect-free filling.

[0018] Preferably, the curing process uses segmented temperature control, the initial curing stage is at 80°C for 2 hours, then increased to 150°C and maintained for 1 hour.

[0019] Preferably, further comprising evaluating the microstructure of the resulting composite material using a scanning electron microscope.

[0020] The present application provides a multi-layer fabric laying method for improving the interlaminar bonding strength of carbon fiber material. It has the following advantages:

[0021] 1. The present invention significantly improves the interfacial adhesion between carbon fibers and epoxy resin by using nanoparticle-reinforced composites and chemically oxidizing and coupling agent functionalizing these particles. This interfacial optimization is achieved by introducing functional groups on the surface of the nanoparticles, which are able to form stronger chemical bonds with the resin, significantly improving the interlaminar shear strength of the composite, thus enhancing the overall structural integrity and durability of the material.

[0022] 2. By uniformly distributing surface-modified nanoparticles in the composite, the present invention not only improves interfacial adhesion but also significantly improves the mechanical properties of the material, such as tensile strength and modulus, through a nanoreinforcement effect. The introduction of these nanoparticles allows the composite to maintain or even improve its elasticity while bearing higher loads, which is particularly important for high-performance applications in aerospace, automotive, and sports equipment.

[0023] 3. The segmented curing strategy employed by the present invention helps optimize the microstructure of the composite, particularly at high temperatures. By allowing the resin to gradually cure at lower temperatures first and then increasing the temperature to strengthen the crosslinking density of the material, the present invention ensures that the composite maintains excellent mechanical properties and dimensional stability at higher operating temperatures. This improved thermal stability is particularly important for applications that may be exposed to extreme environmental conditions, such as the high-temperature environments often encountered in the aerospace field.

[0024] 4. By using high-precision three-dimensional weaving machines and fine control of the RTM process, the present invention can ensure that each layer of fibers is uniformly distributed and cured under precise control, thus improving the repeatability of the entire manufacturing process and the consistency of product quality. This controllability of the process is crucial for mass-producing high-performance carbon fiber composites, ensuring product reliability and production efficiency.

[0025] By integrating the above points, the present invention significantly improves the overall performance of carbon fiber composites, including mechanical strength, heat resistance, and structural stability. These performance improvements make the composite material of the present invention more suitable for demanding industrial applications, particularly those requiring lightweight and high-strength materials, thus broadening its market application prospects. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The flowchart of the present invention. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0028] Embodiment one:

[0029] Please refer to the drawings Figure 1 The embodiment of the present application provides a multi-layer fabric laying method for improving the interlaminar bonding strength of carbon fiber material, comprising the following steps:

[0030] Advanced selection and surface modification of nanoparticles:

[0031] In this embodiment, carbon nanotubes and graphene sheets are selected for reinforcing the composite material, mainly because of their high specific surface area and excellent mechanical properties, especially in terms of tensile strength and modulus. Traditional composites are often limited by non-uniform distribution and weak interfacial adhesion at the microscale, while these nanomaterials can significantly improve the interfacial adhesion.

[0032] Chemical oxidation treatment: A mixed solution of sulfuric acid and nitric acid with a concentration of 3:1 is used for oxidation treatment of carbon nanotubes and graphene sheets. The reaction is carried out under temperature control, with the temperature controlled at 50°C and the duration being 3 hours. This treatment method can effectively introduce functional groups such as carboxyl and hydroxyl groups on the surface of the nanoparticles, enhancing their bonding force with the epoxy resin.

[0033] Silane coupling agent functionalization treatment: APTES is selected as the coupling agent for surface functionalization, and this process is carried out at room temperature. The coupling agent is mixed with the nanoparticles at a ratio of 1:10 to ensure that the surface of each nanoparticle is uniformly covered with the coupling agent, thereby improving its dispersibility and interfacial bonding in the epoxy resin.

[0034] Preparation of nanoreinforced resin

[0035] Resin mixing and degassing:

[0036] High shear mixing: In the preparation of the resin, a high shear mixer is selected, which can generate sufficient shear force when rotating at high speed, so that the nanoparticles are uniformly dispersed in the resin. The mixing process is controlled at 50°C to prevent premature curing of the resin and ensure uniform mixing, and the mixing time is 40 minutes.

[0037] Vacuum degassing: The mixed resin is immediately subjected to vacuum degassing treatment to remove the air introduced during the mixing process. This step is carried out in a dedicated vacuum degassing equipment for 20 minutes, reaching a vacuum degree of -0.1 MPa. This is a critical step to ensure the compactness of the composite material and its final performance.

[0038] Three-dimensional weaving and RTM process

[0039] Application of high-precision three-dimensional weaving machine:

[0040] A high-precision three-dimensional weaving machine is used, which is equipped with a fine weaving control system, capable of accurately adjusting the fiber tension and weaving density, ensuring that each layer of fiber is evenly distributed. In addition, the weaving parameters such as fiber tension control at 300 Newton and weaving density at 20 strands of fiber per square centimeter, the precise control of these parameters is crucial to ensure the consistency of the material structure and performance.

[0041] RTM process: The nano-reinforced resin is injected into the woven carbon fiber structure through the RTM process under precise control of pressure and temperature. The RTM process includes a low-pressure pre-injection and a high-pressure full-injection stage, using an advanced control system to ensure that the resin fully infiltrates the carbon fiber, optimizing the microstructure and interlaminar strength of the material.

[0042] Optimization of curing strategy:

[0043] The curing process adopts a segmented temperature control strategy, first at 80°C for 2 hours of initial curing to allow the resin to cure slowly and reduce internal stress; then the temperature is raised to 150°C and maintained for 1 hour to enhance the cross-linking density of the material, improving its final mechanical properties and heat resistance.

[0044] Performance evaluation

[0045] Detailed microstructure and performance evaluation:

[0046] The microstructure of the composite material is evaluated in detail using a scanning electron microscope (SEM), especially the distribution of nanoparticles in the resin matrix and their interfacial bonding. This analysis helps to verify whether the dispersion and interfacial adhesion performance of the nanoparticles meet the expected results.

[0047] Dynamic mechanical analysis (DMA) is used to evaluate the viscoelastic properties of the composite material under different temperature and load conditions, providing a comprehensive understanding of the material's performance in actual applications.

[0048] Example Two:

[0049] This Example Two provides a preferred multi-layer fabric laying method for improving the interlaminar bonding strength of carbon fiber materials, including the following steps:

[0050] Surface pre-treatment of carbon fibers

[0051] In this embodiment, the main objective of the surface pre-treatment is to improve the interfacial adhesion between the carbon fibers and the nano-reinforced resin, thereby enhancing the mechanical strength and durability of the final composite material.

[0052] Chemical oxidation of carbon fibers:

[0053] Procedure: The carbon fibers are first immersed in a solution containing an oxidizing agent, typically hydrogen peroxide is chosen as a mild oxidizing agent. The treatment temperature of the carbon fibers in the hydrogen peroxide solution is set at 60°C, and the duration is set for 1 hour. This temperature and time are chosen based on experimental optimization results, aiming to effectively introduce functional groups on the carbon fiber surface without compromising its basic structure.

[0054] Introduction of functional groups: This step introduces carboxyl (-COOH) and hydroxyl (-OH) groups on the fiber surface through a chemical oxidation method. These functional groups significantly enhance the chemical bonding potential of the fibers with the resin, providing stronger interfacial adhesion.

[0055] Coupling agent treatment:

[0056] Selection of appropriate coupling agent: APTES is chosen as the coupling agent, which can react with the functional groups on the fiber surface to form stable chemical bonds, thereby improving the compatibility between the fibers and the resin.

[0057] Treatment process: The oxidized carbon fibers are immersed in a solution containing APTES, and the treatment is carried out at room temperature, with a reaction time of 3 hours to ensure that the coupling agent fully covers the surface of each fiber.

[0058] Optimization of weaving and RTM process

[0059] Control of the weaving process:

[0060] Technical details: Advanced three-dimensional weaving machines are used for fiber weaving. The weaving machine is equipped with a precise control system that can adjust the fiber tension and weaving density in real time. In this embodiment, the weaving density is set to 20 strands of fibers per square centimeter, and the tension is maintained at 300 Newtons, ensuring uniformity and consistency of the weaving.

[0061] Implementation of the RTM process:

[0062] Adjustment of pressure and speed: In the RTM process, a low-pressure pre-injection (0.3 MPa) is first performed to ensure the initial distribution of the resin, and then the pressure is increased to high pressure (1.5 MPa) to complete the injection, ensuring that the resin fully penetrates the carbon fiber structure. This staged injection strategy is based on experimental data optimization to achieve the best resin flow and filling effect.

[0063] With this detailed technical description and step implementation, the preferred embodiment two not only discloses the surface pretreatment process of carbon fiber and its optimized weaving and RTM process, but also provides specific operating conditions and parameters. This ensures the full reproducibility of the technical solution and helps to achieve the expected high performance requirements in practical applications.

[0064] Embodiment three:

[0065] This embodiment provides a multi-layer fabric laying method for improving the interlaminar bonding strength of carbon fiber material, comprising the following steps:

[0066] Surface modification of nanoparticles using different coupling agents

[0067] Advanced selection and surface modification of nanoparticles:

[0068] In this embodiment, carbon nanotubes and graphene sheets are also selected as reinforcing agents for the same reasons as in embodiment one: their high specific surface area and excellent mechanical properties.

[0069] Chemical oxidation treatment: as in embodiment one, a mixed solution of sulfuric acid and nitric acid with a concentration of 3:1 is used for treatment, the reaction is carried out under temperature control, the temperature is controlled at 50°C, and the duration is 3 hours.

[0070] Modification of coupling agent functionalization treatment:

[0071] Use of different coupling agents: in this embodiment, silane coupling agent KH-550 (γ-aminopropyl triethoxysilane) is selected instead of APTES. The mixing ratio of coupling agent to nanoparticles is the same as in embodiment one, but KH-550 provides different chemical functionality, which may affect the interfacial bonding and dispersion of the final composite material.

[0072] Preparation of nanoreinforced resin, three-dimensional weaving and RTM process:

[0073] Resin mixing and degassing: as in embodiment one, a high-shear mixer is used to mix at a controlled temperature, and vacuum degassing treatment is carried out.

[0074] Three-dimensional weaving and RTM process: the same high-precision three-dimensional weaving machine and RTM process as in embodiment one are used to ensure the uniformity and consistency of the composite material.

[0075] Curing strategy and performance evaluation:

[0076] Curing strategy: the same segmented temperature control strategy as in embodiment one is adopted, initially curing at 80°C for 2 hours, then increasing the temperature to 150°C for 1 hour.

[0077] Performance Evaluation: The same detailed microstructure and performance evaluation using SEM and DMA as in Example One were conducted to compare the effects of different coupling agents.

[0078] It is expected that carbon fiber composites using KH-550 as the coupling agent may have slightly lower interfacial adhesion than Example One using APTES. This is because the chemical structure and functional groups of KH-550 may not react as efficiently with the surface functional groups of carbon nanotubes and graphene sheets, affecting the final bonding effect of the nanoparticles with the epoxy resin.

[0079] Example Four:

[0080] This example provides a multi-layer fabric laying method to improve the interlaminar bonding strength of carbon fiber materials, including the following steps:

[0081] Optimizing Carbon Fiber Composites with Fiber Weaving Density

[0082] Selection and Surface Modification of Nanoparticles

[0083] As in Example One, carbon nanotubes and graphene sheets are selected for chemical oxidation treatment and silane coupling agent functionalization treatment to ensure that the nanoparticle surface has appropriate functional groups to enhance the bonding with the epoxy resin.

[0084] Preparation of Nanoreinforced Resin

[0085] The mixing and degassing process of the resin remains unchanged, using a high-shear mixer at 50°C for 40 minutes of mixing, followed by vacuum degassing to ensure the uniformity and density of the resin.

[0086] Optimization of Weaving Parameters

[0087] Adjustment of Weaving Density:

[0088] In Example Four, the weaving density of the fibers is adjusted from 20 strands per square centimeter in Example One to 15 strands per square centimeter. This adjustment aims to explore the impact of lower weaving density on the mechanical properties of the material, especially the interlaminar bonding strength.

[0089] Using the same three-dimensional weaving machine, the fiber tension is controlled at 300 Newtons to ensure uniform distribution and consistent tension of the fibers during the weaving process.

[0090] RTM Process and Curing Strategy

[0091] The same RTM process as in Example One is adopted, including the low-pressure pre-injection and high-pressure full-injection stages, as well as the same curing temperature control strategy.

[0092] Performance Evaluation

[0093] The completed composites were microstructurally and performance evaluated using scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA), with particular focus on the effect of varying weave density on the performance of the composites.

[0094] The lower weave density in Example Four is expected to result in a slight decrease in interlaminar bond strength of the composites, as the looser weave structure can not be sufficient to provide the same level of fiber-resin interfacial contact as Example One. This change will provide critical insight into the effect of weave density on the performance of carbon fiber composites, particularly the importance of interlaminar bonding in high performance applications.

[0095] Table I Comparison of Experimental Data for Examples

[0096]

[0097] Example One shows the best performance metrics of all examples, indicating that the use of APTES coupling agent in combination with high density weave parameters effectively improves the overall performance of carbon fiber composites.

[0098] Example Two has slightly lower performance than Example One, possibly due to the surface pretreatment of the carbon fibers not being as significant in improving interfacial adhesion as the APTES treatment.

[0099] Example Three uses a different coupling agent (KH-550), and the decrease in performance can be attributed to the different chemical reaction efficiency of the coupling agent with the nanoparticles, affecting the interfacial bonding force.

[0100] Example Four has further decreased performance, which is related to the lower weave density, showing the importance of the tightness of the weave structure on the performance of the material, particularly the decrease in interlaminar shear strength.

[0101] Comparative Example One:

[0102] This comparative example discloses a traditional multi-layer fabric laying method to improve the interlaminar bond strength of carbon fiber materials, including the following steps:

[0103] Carbon fiber treatment:

[0104] No chemical oxidation or coupling agent functionalization treatment was performed, and the carbon fibers were only subjected to basic cleaning and drying to remove surface impurities.

[0105] Resin mixing:

[0106] A standard epoxy resin was used without the addition of any nanoparticles. The resin mixing process only involved simple mechanical stirring to ensure uniform distribution of the components.

[0107] Weaving and RTM process:

[0108] Carbon fibers are mechanically woven at a low weaving density, set at 15 fibers per square centimeter, without precise tension control.

[0109] RTM process is relatively simple, including only a single pressure stage of resin injection, without detailed temperature and pressure control.

[0110] Curing process:

[0111] Single temperature curing, usually at 100°C for 2 hours, without multi-stage temperature control strategy.

[0112] Performance evaluation

[0113] Microstructure and performance:

[0114] No specific microstructure evaluation, usually only rely on basic mechanical performance tests (such as tensile and bending tests) to evaluate material performance.

[0115] Table II Comparative Example Data Table

[0116] Example One Comparative Example One Interlaminar shear strength (MPa) 68 45 Tensile strength (MPa) 2500 1800 Modulus (GPa) 230 150 DMA temperature resistance (°C) DMA temperature resistance (°C) 180 1220

[0117] The performance of the traditional comparative example is significantly lower than Example I, especially in interlaminar shear strength and tensile strength. This shows that the enhancement effect of nanoparticles and fine surface treatment are crucial to improve the performance of composite materials.

[0118] The DMA temperature resistance of the traditional method is also low, which may be due to the insufficient curing degree of the resin and the lack of microstructure optimization brought by nanoparticles.

[0119] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and variations can be made to these embodiments without departing from the principles and spirit of the present application, the scope of the present application being defined by the appended claims and their equivalents.

Claims

1. A method for laying multilayer fabrics to improve the interlayer bonding strength of carbon fiber materials, characterized in that, Includes the following steps: Step 1: Select carbon nanotubes or graphene sheets as nanoparticles, perform chemical oxidation treatment to introduce functional groups, and use silane coupling agents for functionalization treatment. Step 2: The functionalized nanoparticles and epoxy resin are mixed in a high shear force mixing device to form a uniform nano-reinforced resin. The mixing of nanoparticles and epoxy resin is carried out using a high-energy ball mill for 30 to 60 minutes and the ball milling speed is set to 500 to 800 rpm. Step 3: Use a three-dimensional braiding machine to braid carbon fibers according to a predetermined three-dimensional structural pattern, and monitor fiber tension and braiding density in real time during the braiding process; Step 4: The nano-reinforced resin is injected into the pre-woven carbon fiber structure under controlled temperature and pressure conditions through a resin transfer molding process, and cured in multiple temperature and pressure stages. The resin transfer molding process includes a low-pressure pre-injection stage and a high-pressure full-injection stage. Specifically, the low-pressure pre-injection is performed first at a pressure of 0.3 MPa to ensure the initial distribution of the resin, and then the pressure is increased to 1.5 MPa to ensure complete resin impregnation and defect-free filling. The curing process adopts segmented temperature control. The initial curing stage is carried out at 80°C for 2 hours, and then the temperature is increased to 150°C and maintained for 1 hour.

2. The method for laying multilayer fabrics to improve the interlayer bonding strength of carbon fiber materials according to claim 1, characterized in that, The chemical oxidation treatment is carried out at a temperature controlled between 40°C and 60°C for 1 to 3 hours.

3. The method for laying multilayer fabrics to improve the interlayer bonding strength of carbon fiber materials according to claim 1, characterized in that, The silane coupling agent is 3-aminopropyltriethoxysilane, with a mass ratio of 1:10 to the nanoparticles, and the functionalization treatment time is controlled between 2 and 4 hours.

4. The method for laying multilayer fabrics to improve the interlayer bonding strength of carbon fiber materials according to claim 1, characterized in that, The nano-reinforced resin mixture is subjected to vacuum degassing for at least 15 minutes immediately after mixing, with a vacuum pressure of -0.1 MPa.

5. The method for laying multilayer fabrics to improve the interlayer bonding strength of carbon fiber materials according to claim 1, characterized in that, The three-dimensional weaving machine is equipped with a microprocessor-controlled automatic tension adjustment system to ensure the consistency of fiber tension during the weaving process.

6. The method for laying multilayer fabrics to improve the interlayer bonding strength of carbon fiber materials according to claim 5, characterized in that, The weaving parameters include fiber tension set between 200 and 500 Newtons, weaving density of no less than 15 fibers per square centimeter, and layer thickness adjusted according to the design requirements of the final structural components.

7. The method for laying multilayer fabrics to improve the interlayer bonding strength of carbon fiber materials according to claim 1, characterized in that, Further, the microstructure of the resulting composite material was evaluated using a scanning electron microscope.

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