A carbon fiber wheel surface nano-silica modification treatment method

Abstract

The present application belongs to the technical field of wheel surface treatment, and particularly relates to a carbon fiber wheel surface nano-silica modification treatment method, which comprises: pretreating the carbon fiber wheel through ultrasonic cleaning with acetone; constructing a micro-nano rough structure and oxygen-containing functional groups on the surface of the carbon fiber wheel; adopting nano-silica sol to dip coat the surface of the carbon fiber wheel and realize silane-nano SiO2 composite grafting; performing secondary plasma activation on the surface of the carbon fiber wheel after the nano-silica sol is dip coated; and adopting stepwise temperature rising to perform cross-linking and solidification forming on the surface of the carbon fiber wheel after the secondary plasma activation. The present application makes the nano-silica uniformly distributed on the surface of the carbon fiber, chemically bonds with the active sites on the surface of the carbon fiber, and significantly improves the interface bonding strength between the carbon fiber and the resin matrix and the service life of the wheel.

Description

Technical Field

[0001] This invention belongs to the field of wheel surface treatment technology, specifically relating to a method for modifying the surface of carbon fiber wheels with nano-silica, which is applicable to the surface protection of lightweight automotive components. Background Technology

[0002] As an innovative approach to alleviating urban logistics and traffic problems, underground pipeline logistics transportation systems have seen increasing maturity in recent years. The transportation vehicles used in these systems can be AGVs or unmanned vehicles. CN202411379909.2 discloses a linear motor structure for logistics transportation, including a steering wheel. Potential materials for this steering wheel include steel wheels, aluminum alloy wheels, magnesium alloy wheels, and carbon fiber wheels. Among these, carbon fiber reinforced polymer (CFRP) composites, with their unique performance advantages, have shown great potential for application in the wheel field, driven by advancements in material technology and molding processes. Currently, the core requirements for automobiles are weight reduction and fuel efficiency. Carbon fiber wheels are 40%-50% lighter than aluminum alloy wheels of the same size and 60%-70% lighter than steel wheels, significantly improving range, reducing tire rolling resistance, and decreasing fuel consumption, thus meeting energy conservation and emission reduction requirements. Furthermore, in scenarios with stringent performance requirements, the high specific strength of carbon fiber wheels can withstand greater impact loads and has a long fatigue life.

[0003] However, existing carbon fibers still face considerable technical challenges in the practical application of high-performance wheel manufacturing. For example, while carbon fibers themselves have high hardness, the overall hardness of carbon fiber resin composites is still lower than that of aluminum alloy and steel wheels. Furthermore, the interface between carbon fibers and resin contains micropores, making the resin easily peeled off during wear. Exposed carbon fiber bundles, lacking matrix support, are prone to fiber pull-out, leading to wear marks and indentations on the inner side of the rim where it rubs against the tire, and on the contact area between the wheel hub and the bearing, after long-term use. In addition, the smooth surface and strong chemical inertness of carbon fibers, lacking active functional groups, result in insufficient chemical bonding with the resin and weak interfacial bonding strength with the resin matrix. This makes the fibers prone to debonding under high stress and complex working conditions, affecting the overall performance and service life of the wheel. Moreover, insufficient weather resistance makes it susceptible to surface aging and performance degradation during long-term use. Summary of the Invention

[0004] As mentioned earlier, the chemical inertness and low surface energy of carbon fiber limit its bonding strength with the matrix material, resulting in deficiencies in hardness and wear resistance of the composite material. To address these issues, this invention proposes using nano-silica (SiO2) as the core modifier, combined with a controllable process, to achieve efficient surface treatment of carbon fiber wheels.

[0005] The complete technical solution of this invention includes:

[0006] A method for modifying the surface of carbon fiber wheels with nano-silica includes the following steps:

[0007] (1) The carbon fiber wheels are pretreated by ultrasonic cleaning with acetone;

[0008] (2) Constructing micro-nano rough structures and adding oxygen-containing functional groups to the surface of carbon fiber wheels;

[0009] (3) The surface of carbon fiber wheels was coated with nano-silica sol and silane-nano-SiO2 composite grafting was achieved;

[0010] (4) The carbon fiber wheel surface after being coated with nano-silica sol is subjected to secondary plasma activation;

[0011] (5) The carbon fiber wheel surface after secondary plasma activation is cross-linked and cured by step heating.

[0012] Further, step (1) specifically includes: immersing the carbon fiber wheel completely in an acetone solution with an acetone concentration ≥99.5%, placing it in an ultrasonic cleaning device for cleaning, with an ultrasonic power of 300W, an ultrasonic temperature of 40℃, and a cleaning time of 60min.

[0013] Furthermore, after cleaning, the product is rinsed three times with deionized water for 5 minutes each time, and then placed in a vacuum oven to dry at 80°C for 4 hours with a vacuum degree of -0.1MPa.

[0014] Furthermore, in step (2), a single plasma activation is used to construct a micro-nano rough structure and add oxygen-containing functional groups to the carbon fiber wheel.

[0015] Furthermore, in step (2), a two-stage electrochemical oxidation process is used to construct the micro-nano rough structure and add oxygen-containing functional groups to the carbon fiber wheel.

[0016] Furthermore, the first plasma activation is as follows: the dried wheel is fixed in the plasma reaction chamber, an argon / oxygen mixture is introduced with a gas volume ratio of Ar:O2=9:1 and a total flow rate of 50 sccm, the equipment is started to perform pulsed plasma treatment, the electrode distance is 20 mm, the pulse mode is used, the switching time is 2:1, and the plasma power is controlled in segments, specifically, first 800W for 60s, then 1200W for 40s, and finally 800W for 20s, with a total treatment time of 120s.

[0017] Further, step (4) is as follows: the coated wheel is placed into the plasma device, a mixed gas is introduced, the volume ratio of the mixed gas is Ar:O2=8:2, the total flow rate is 40sccm, the continuous plasma jet treatment of the coating and fiber interface area is started, the plasma power is 800W, the treatment time is 120s, the gas pressure is 100Pa, and the jet distance is 15mm.

[0018] Furthermore, during the secondary plasma activation process, the wheel is kept rotating to ensure uniformity, with a rotation speed of 5 r / min.

[0019] Furthermore, the stepwise heating in step (5) is as follows: first, keep warm at 100℃ for 30 minutes, then keep warm at 120℃ for 1 hour, and finally keep warm at 150℃ for 30 minutes.

[0020] Furthermore, carbon fiber wheels are obtained using the aforementioned processing method.

[0021] The beneficial effects of this invention compared to the prior art are as follows:

[0022] 1. Using nano-silica (SiO2) as the core modifier and combined with a controllable process, efficient surface treatment of carbon fiber wheels is achieved. Nano-silica (SiO2) has a high specific surface area, good dispersibility and chemical stability. Through chemical grafting, nano-silica is uniformly distributed on the carbon fiber surface and chemically bonded to the active sites on the carbon fiber surface, which significantly improves the interfacial bonding strength between carbon fiber and resin matrix, and the interfacial shear strength is increased by 70%-80%.

[0023] 2. The hydroxyl groups on the surface of nano-silica chemically bond with the active sites (carboxyl and hydroxyl groups) on the carbon fiber surface, forming a strong interfacial layer. Simultaneously, the high specific surface area and porous structure of nano-silica increase the contact area between the fiber and the resin matrix, promoting resin penetration and diffusion on the fiber surface, thereby significantly improving the interfacial bonding strength. This further enhances the hardness and wear resistance of the wheel; the hardness after SiO2 grafting is approximately 50-70% higher than that of the carbon fiber matrix, and after plasma activation, it increases to 80%, while reducing the wear rate by 30-50%.

[0024] 3. Nano-silica forms a protective layer on the surface of carbon fiber, preventing it from being corroded by the external environment during long-term use. Salt spray resistance is increased by approximately 65%, thus extending the lifespan of the wheels. Furthermore, the processing method of this invention is simple and convenient, requires no complex equipment, is low-cost, and suitable for large-scale industrial production. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below. Referring to the accompanying drawings will provide a clearer understanding of the features and advantages of the present invention. The drawings are illustrative and should not be construed as limiting the present invention in any way. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort. Wherein:

[0026] Figure 1 This is a SEM image of the morphology of the composite modified coating of the present invention. Detailed Implementation

[0027] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0028] 1. Preprocessing

[0029] The carbon fiber wheels were completely immersed in an acetone solution with a concentration ≥99.5% (analytical grade), and then cleaned using an ultrasonic cleaner at 300W power and 40℃ for 60 minutes to remove surface adhesive, mold release agent residue, and dust. After cleaning, the wheels were rinsed three times with deionized water for 5 minutes each time, and then placed in a vacuum oven to dry. The drying temperature was 80℃ for 4 hours, and the vacuum degree was -0.1MPa. Vacuum drying avoids moisture residue and partially releases the internal stress accumulated during the wheel molding process.

[0030] 2. Functionalization and construction of micro / nano rough structures: This step can be carried out using one of the following two methods.

[0031] (1) Primary plasma activation

[0032] The dried wheel was fixed in the plasma reaction chamber, and an argon / oxygen mixture was introduced with a volume ratio of Ar:O2=9:1 and a total flow rate of 50 sccm. The equipment was started for pulsed plasma treatment with an electrode distance of 20 mm, using pulse mode and a switching time of 2:1. The plasma power was controlled in segments: first 800W for 60 seconds, then 1200W for 40 seconds, and finally 800W for 20 seconds, for a total treatment time of 120 seconds. The treatment pressure in the plasma reaction chamber was 10 Pa. After treatment, the process was quickly moved to the next step.

[0033] This single-stage plasma activation process uses high-energy plasma particles (Ar⁺, O⁺) to physically bombard the wheel surface, etching it to form a micro-nano-scale uneven structure, increasing the surface roughness Ra to 1.5-2.0 μm. Oxygen, as the reactant gas, can directionally introduce oxygen-containing functional groups such as hydroxyl (-OH) and carboxyl (-COOH), increasing the surface energy. Segmented power control avoids local overheating, and the pulsed mode reduces damage to the carbon fiber matrix, significantly improving the functional group density compared to traditional single-power treatment. Furthermore, the carbon fiber single-filament strength retention rate can reach up to 95%, and the damage rate can be controlled within 3%. This solves the problems of uneven functional group distribution and low density in traditional plasma activation, as well as excessive etching and strength loss of the fiber surface caused by continuous high-power treatment. The synergistic effect of the micro-nano rough structure and functional groups provides a dual basis for subsequent sol-gel coating, combining physical anchoring and chemical bonding.

[0034] (2) Two-stage electrochemical oxidation functionalization treatment

[0035] 1) First-stage electrochemical oxidation for trench construction

[0036] The pretreated wheel was fixed in an electrolytic cell, with graphite as the cathode and the wheel as the anode, and immersed in an alkaline electrolyte for oxidation etching. The electrolyte was a 20wt% NaOH aqueous solution. The current density was 0.7~1A / dm², the temperature was 30-50℃, and the time was 20~30s. After etching, the wheel was rinsed three times with deionized water at a temperature of 25℃ for 5 minutes each time, forming micron-sized trenches with a depth of 1.2-1.8μm and a width of 0.5-1.0μm.

[0037] 2) Secondary electrochemical oxidation achieves oxygen-containing functionalization

[0038] After the first-stage electrochemical oxidation, the wheel is transferred back to the electrolytic cell for fixation. The carbon fiber wheel is used as the anode and the stainless steel plate as the cathode. A 5% NH4HCO3 solution is used as the electrolyte to ensure full contact between the electrode and the electrolyte. The power supply is started to carry out the second-stage electrochemical oxidation, with the current density controlled at 0.06–0.12 A / dm² and the processing time at 60–90 s. The temperature of the electrolyte is also maintained in the range of 30–50℃. Through the anodic oxidation reaction, oxygen-containing functional groups (-COOH, -OH) are formed on the fiber surface, which improves the surface roughness and chemical activity.

[0039] In the two-stage electrochemical oxidation process described above, the first-stage reaction is dominated by trench construction, with the trench construction ratio exceeding 75%. Active oxygen atoms are generated during anodic discharge. These active oxygen atoms act on the edges of the sheets and amorphous regions, causing the surface carbon layer to peel off. This achieves selective etching of amorphous regions and defects, forming micron-sized trenches, while a small number of functional groups are generated.

[0040] The subsequent secondary electrochemical oxidation primarily achieves the formation of oxygen-containing functional groups (over 85%), while simultaneously refining the trenches. This includes gently etching away edge burrs and residual loose carbon fragments from the primary trenches, and homogenizing the roughness of the trench inner walls. Ultimately, the O / C ratio can be increased to 0.32-0.35, and the total functional group density reaches 1.1 × 10⁻⁻⁻⁶. 5 -1.3×10⁻ 6 The concentration of mol / m² meets the bonding requirements of subsequent silanization treatment. This two-stage treatment achieves a synergistic effect of physical anchoring followed by chemical bonding, forming a composite surface with deep trenches and high-density functional groups. This ensures both mechanical interlocking strength and enhanced chemical bonding.

[0041] 3. Preparation of nano-silica sol

[0042] Add ethanol, deionized water, nano-SiO2, and KH-550 silane coupling agent in sequence according to the proportion. In addition, 0.5% of titanate coupling agent by mass can be added to improve the compatibility between SiO2 and resin. After stirring evenly, ultrasonic vibration is performed at a power of 300W for 30 minutes.

[0043] 4. Carbon fiber surface coating and silane-nano SiO2 composite grafting

[0044] After plasma activation or two-stage electrochemical oxidation, the wheel is fixed in the dip-coating equipment fixture and immersed in a nano-silica sol solution for coating. The sol temperature is 30°C, and the liquid level ensures complete immersion of the wheel. Ultrasonic vibration is used during this process, and the immersion speed and time are matched to the stress requirements of different parts (the rim has the highest wear resistance requirements, so the coating is slightly thicker). Uniform immersion speed prevents sol dripping, and a gentle airflow during draining promotes the even distribution of excess solution, forming a continuous coating. A dense coating is formed on the fiber surface through hydrolysis and condensation reaction, repairing oxidation and etching defects. Chemical bonds (Si-OC) are formed through the reaction of silanol groups (-Si-OH) with oxygen-containing functional groups, while the amino groups (-NH2) of the coupling agent react with the isocyanate groups (-NCO) in the resin matrix (such as polyurethane) to achieve grafting. After completion, excess sol is drained at room temperature.

[0045] Preferably, when coating a wheel treated with a two-stage electrochemical oxidation process with a composite silane coupling agent and then performing a grafting reaction, the parameters of each process can be comprehensively optimized, including relevant parameters in both the two-stage electrochemical oxidation and grafting processes, to improve the overall performance of the treated wheel. The performance indicators of interest include fatigue life and peel strength. Based on this approach, by analyzing the mechanisms of the electrochemical oxidation and grafting processes and combining historical data, parameters with significant influence are selected for fitting, and a relevant correlation model is established as follows:

[0046]

[0047] In the formula, This represents dynamic radial fatigue life, measured in cycles. The concentration of silane in the composite silane solution (wt%). The amount of nano-SiO2 added to the composite silane solution (wt%). It is a first-order oxidative damage index (A·s / dm²), and , This represents the first-order electrochemical oxidation current density. This refers to the first-order electrochemical oxidation time.

[0048] Peel strength, in N / mm. The density index of second-order functional groups (A·s) 0 · 5 / dm²), and This represents the second-order electrochemical oxidation current density. This refers to the second-order electrochemical oxidation time. , , , , , , All are correlation coefficients from the fitting process. The value range is 8×10 3 ~1×10 4 , The value range is 2 to 5. The value range is 15~28. The value range is 0.01 to 0.03. The value range is 15~35. The value range is 2.5 to 4.7. The value range is 3 to 6. It is an exponent. Its value ranges from 0.4 to 0.7.

[0049] As can be seen from the above model, within the applicable range, fatigue life is exponentially positively correlated with silane concentration, because amino groups inhibit crack initiation. Current density has a multiplicative effect with time, which affects the groove depth and density on the fiber surface. However, excessive addition will lead to a decrease in tensile properties and affect life. The amount of nano-SiO2 added has a positive correlation with peel strength within a certain range, which helps to construct a multi-level interface between fiber, silane, SiO2 and resin. However, excessive addition may also lead to agglomeration, increase local stress, and affect the above properties.

[0050] Based on the above model, considering the comprehensive impact on the aforementioned performance, the following optimized parameter values ​​are obtained: J1=0.83, t1=24s, J2=0.10, t2=72s. It is 12.8 wt%. It is 0.52 wt%.

[0051] 5. Plasma-assisted secondary enhancement to achieve interfacial bonding activation and coating densification.

[0052] The coated wheel was placed in a plasma device, and an optimized mixture of gases was introduced, with a volume ratio of Ar:O2 = 8:2 and a total flow rate of 40 sccm. Continuous plasma jet treatment was initiated to treat the interface area between the coating and the fiber. The plasma power was 800W, the treatment time was 120s, the gas pressure was 100Pa, and the jet distance was 15mm. During the treatment, the wheel was kept rotating slowly to ensure uniformity, with a wheel rotation speed of 5r / min.

[0053] This step primarily targets the tiny pores remaining in the coating after application. To prevent these pores from reducing the bonding strength between the coating and the fiber interface and causing easy peeling, a secondary plasma is used to activate the active sites on the coating surface and the fiber. This promotes the further reaction between the silanol groups (-Si-OH) on the nano-SiO2 surface and the hydroxyl groups (-OH) on the fiber surface to form Si-OC covalent bonds, enhancing the bonding strength with the resin during subsequent curing. The rotation of the wheel ensures that the plasma acts uniformly on complex curved surfaces such as the rim, spokes, and hub, avoiding insufficient local reinforcement.

[0054] 6. Curing and molding achieves step-by-step cross-linking reinforcement.

[0055] The wheels, after secondary plasma treatment, were placed in an oven with an air atmosphere and a ventilation rate of approximately 0.5 m³ / min. A stepped heating process was used for curing: first, holding at 100℃ for 30 minutes, then at 120℃ for 1 hour, and finally at 150℃ for 30 minutes. The low-temperature stage promoted the slow evaporation of the solvent in the sol, avoiding rapid evaporation that could cause coating cracking. The medium-temperature stage (120℃) further initiated the cross-linking reaction between the silane coupling agent and nano-SiO2, forming a three-dimensional network structure. The high-temperature stage (150℃) enhanced the stability of the Si-OC bond, improving the bonding strength between the coating and the fiber. This stepped heating method avoids the stress concentration and cracking problems caused by traditional isothermal curing, as well as the insufficient hardness and poor wear resistance caused by inadequate cross-linking. It improves both the degree of cross-linking and hardness of the coating, eliminating curing cracking, and resulting in a surface morphology as shown. Figure 1As shown, the fiber surface is uniformly covered with a coating in a continuous network structure. The coating fills the sharp grooves formed by plasma etching, which moderately reduces the surface roughness, but still retains enough micro-nano morphology to achieve mechanical interlocking. The SiO2 particles are uniformly distributed in the silane coating without agglomeration.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A carbon fiber wheel surface nanosilica modification treatment method, characterized by, Includes the following steps: (1) The carbon fiber wheels are pretreated by ultrasonic cleaning with acetone; (2) Constructing micro-nano rough structures and adding oxygen-containing functional groups to the surface of carbon fiber wheels; (3) The surface of carbon fiber wheels was coated with nano-silica sol and silane-nano-SiO2 composite grafting was achieved; (4) The carbon fiber wheel surface after being coated with nano-silica sol is subjected to secondary plasma activation; (5) The carbon fiber wheel surface after secondary plasma activation is cross-linked and cured by step heating.

2. The carbon fiber wheel surface nanosilica modification treatment method according to claim 1, characterized in that, Step (1) specifically includes: immersing the carbon fiber wheel completely in an acetone solution with an acetone concentration ≥99.5%, cleaning it in an ultrasonic cleaning device with an ultrasonic power of 300W, an ultrasonic temperature of 40℃, and a cleaning time of 60min.

3. The method for modifying the surface of carbon fiber wheels with nano-silica according to claim 2, characterized in that, After cleaning, rinse three times with deionized water for 5 minutes each time, and then place in a vacuum oven to dry at 80°C for 4 hours with a vacuum degree of -0.1MPa.

4. The carbon fiber wheel surface nanosilica modification treatment method according to claim 1, characterized in that, In step (2), a single plasma activation is used to construct the micro-nano rough structure and add oxygen-containing functional groups to the carbon fiber wheel.

5. The method for modifying the surface of carbon fiber wheels with nano-silica according to claim 1, characterized in that, In step (2), a two-stage electrochemical oxidation process is used to construct the micro-nano rough structure and add oxygen-containing functional groups to the carbon fiber wheel.

6. The method for modifying the surface of a carbon fiber wheel with nano-silica according to claim 4, characterized in that, The plasma activation process is as follows: the dried wheel is fixed in the plasma reaction chamber, an argon / oxygen mixture is introduced with a gas volume ratio of Ar:O2=9:1 and a total flow rate of 50 sccm, the equipment is started to perform pulsed plasma treatment, the electrode distance is 20 mm, the pulse mode is used, the switching time is 2:1, and the plasma power is controlled in segments. Specifically, it is first treated with 800W for 60s, then with 1200W for 40s, and finally with 800W for 20s, for a total treatment time of 120s.

7. The method for modifying the surface of carbon fiber wheels with nano-silica according to claim 1, characterized in that, Step (4) is as follows: Place the coated wheel into the plasma device, introduce mixed gas, the volume ratio of the mixed gas is Ar:O2=8:2, the total flow rate is 40sccm, start the continuous plasma jet treatment of the coating and fiber interface area, the plasma power is 800W, the treatment time is 120s, the gas pressure is 100Pa, and the jet distance is 15mm.

8. The method for modifying the surface of a carbon fiber wheel with nano-silica according to claim 7, characterized in that, During the secondary plasma activation process, the wheel is kept rotating to ensure uniformity, with a rotation speed of 5 r / min.

9. The method for modifying the surface of a carbon fiber wheel with nano-silica according to claim 8, characterized in that, In step (5), the stepwise heating is as follows: first, keep warm at 100℃ for 30 minutes, then keep warm at 120℃ for 1 hour, and finally keep warm at 150℃ for 30 minutes.

10. A carbon fiber wheel obtained by the processing method according to any one of claims 1-9.

Images