High-strength hoop and processing method thereof

Abstract

The invention discloses a high-strength hoop and a processing method thereof in the technical field of mechanical connection fasteners. The high-strength hoop comprises the following raw materials: modified carbon fibers, a modified epoxy resin matrix, chopped glass fibers, an antioxidant and an aluminate coupling agent. Cleaning the modified carbon fibers with acetone to remove oil stains, oxidizing the modified carbon fibers with concentrated nitric acid at 80-85 DEG C to generate polar functional groups containing hydroxyl and carboxyl, washing the modified carbon fibers with water until the modified carbon fibers are neutral, drying the modified carbon fibers, immersing the modified carbon fibers into an absolute ethyl alcohol solution of an aluminate coupling agent for ultrasonic dispersion, and curing the modified carbon fibers at 100-105 DEG C; the modified epoxy resin matrix is prepared by heating and melting epoxy resin, adding nano montmorillonite, stirring and dispersing, adding polyamide, an accelerant and a flexibilizer, and carrying out vacuum defoaming at 100-105 DEG C. The hoop has the advantages of high strength, weather resistance and the like by modifying and enhancing interface bonding and matrix toughness, and is suitable for connection under complex working conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical connection fasteners, and in particular to a high-strength clamp and a processing method thereof. Background Art

[0002] The safe operation of power equipment depends on the reliability of various connecting and fixing components. Clamps, among them, are core components for securing cables, pipes, and structural components in equipment like transformers and switchgear. They are subject to the multiple effects of mechanical stress, vibration, shock, and ambient temperature fluctuations over long periods of time. While traditional steel clamps offer basic strength, they are susceptible to rust in harsh environments like humidity and salt spray, leading to structural strength degradation and even fracture and failure. Clamps made of conventional fiber-reinforced composite materials, however, suffer from insufficient fiber-matrix interfacial bonding, which can lead to fiber detachment. Furthermore, they are subject to significant performance degradation due to thermal stress or chemical corrosion over long-term use, making them unable to meet the stringent long-term stability requirements of power equipment. This contradiction hinders the development of high-reliability power equipment.

[0003] As power grid systems upgrade toward higher voltages and larger capacities, clamps must simultaneously possess higher strength, weather resistance, and aging resistance. Traditional material systems have demonstrated significant limitations: metal materials are prone to rust, leading to increased maintenance costs, while conventional composite materials suffer from weak interfacial bonding and insufficient resistance to environmental corrosion. Especially in coastal areas with high levels of salt fog or humid environments, corrosion failure of clamps not only impacts equipment safety but can also cause power outages and significant economic losses. Therefore, developing new clamp materials that combine high strength, corrosion resistance, and long-term stability has become a critical technical requirement for upgrading power equipment components.

[0004] This invention addresses the performance pain points of clamps for power equipment and proposes solutions through material and process innovation. After surface treatment and modification with a coupling agent, the modified carbon fiber significantly improves its bonding strength with the resin matrix; the modified epoxy resin matrix is ​​optimized with ingredients such as nano-montmorillonite to enhance the overall weather resistance of the composite material. The composite material system formed by the synergistic effect of the two effectively resists environmental corrosion and aging while maintaining high strength, providing more reliable protection for key connection parts of power equipment. This technical solution, through the combination of material modification and process control, is expected to break through the performance bottleneck of traditional clamps and contribute to the overall improvement of the safe operation level of power equipment. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-strength clamp and a processing method thereof, which solves the problems that traditional clamps are easily deformed, broken and rusted in high temperature, high pressure and corrosive environments, lack toughness and are easily brittle, and the existing modification methods have weak interface bonding and poor weather resistance.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0007] A high-strength clamp, whose raw materials include, by mass percentage:

[0008] Modified carbon fiber: 25-35%;

[0009] Modified epoxy resin matrix: 45-55%;

[0010] Chopped glass fiber: 10-15%;

[0011] Antioxidants: 0.5-1%;

[0012] Aluminate coupling agent 1: 0.5-1%;

[0013] The modified carbon fiber preparation method comprises the following steps: A1, placing the carbon fiber in an acetone solution for ultrasonic cleaning to remove surface oil stains; A2, then transferring the carbon fiber to a constant temperature box and performing oxidation treatment with concentrated nitric acid at 80-85°C to generate polar functional groups containing hydroxyl and carboxyl groups on the surface of the carbon fiber; after removing the carbon fiber, repeatedly rinsing it with deionized water until it is neutral, and placing it in a vacuum drying oven for drying; A3, finally immersing the dried carbon fiber in an anhydrous ethanol solution of an aluminate coupling agent 2, ultrasonically dispersing it, and curing it at 100-105°C after removing the carbon fiber.

[0014] According to a preferred embodiment of the present invention, the carbon fiber is purchased from Zhongfu Shenying Carbon Fiber Co., Ltd., model SYT49S.

[0015] According to a preferred embodiment of the present invention, the acetone solution is purchased from Sinopharm Chemical Reagent Co., Ltd.

[0016] According to a preferred embodiment of the present invention, the concentrated nitric acid is purchased from Hubei Yihua Group Co., Ltd.

[0017] According to a preferred embodiment of the present invention, the vacuum drying oven is purchased from Shanghai Yiheng Scientific Instrument Co., Ltd. and is model DZF-6020.

[0018] According to a preferred embodiment of the present invention, the aluminate coupling agent 1 and the aluminate coupling agent 2 are purchased from Nanjing Youpu Chemical Co., Ltd. as DL-411-Al model.

[0019] According to a preferred embodiment of the present invention, the chopped glass fibers are purchased from China Jushi Co., Ltd. Model ECS13-4.5-500.

[0020] According to a preferred embodiment of the present invention, the antioxidant is purchased from Hindered Phenol Antioxidant 1010 from Wanhua Chemical Group Co., Ltd.

[0021] The interfacial activation and coupling strengthening of the modified carbon fiber in the present invention are the primary links for performance improvement. The original carbon fiber surface is highly inert and has weak bonding strength. After ultrasonic cleaning with acetone to remove oil stains, concentrated nitric acid oxidation treatment etches a large number of polar functional groups containing hydroxyl (-OH) and carboxyl (-COOH) on the carbon fiber surface through strong oxidizing properties. These functional groups act as "active anchor points" to significantly increase the chemical active sites on the surface, while improving the wettability and roughness of the surface. The aluminoxane group (-O-Al-O-) contained in the aluminate coupling agent molecules subsequently introduced can undergo a condensation reaction (-OH+-OR→-O-+ROH) with the hydroxyl and carboxyl groups on the carbon fiber surface, remove small molecule alcohols (such as isopropyl alcohol), and generate stable Al-OC covalent bonds, thereby constructing a "carbon fiber-coupling agent" interface transition layer on the carbon fiber surface. During the curing process of epoxy resin, the combination of aluminate coupling agent and resin mainly relies on the following synergistic mechanisms: first, the unreacted alkoxy (-OR) or aluminoxane group (-O-Al-O-) in the coupling agent molecule can interact with the epoxy resin molecular chain through physical entanglement or van der Waals force, thereby enhancing the mechanical intercalation of the interface; second, the aluminoxane group in aluminate can act as a Lewis acid, weakly coordinating with the oxygen atom (containing lone pair electrons) of the epoxy group, reducing the ring-opening activation energy of the epoxy group, and indirectly promoting the cross-linking reaction between the epoxy resin and the curing agent (such as polyamide), thereby tightly connecting the carbon fiber and the epoxy resin through "coupling agent bridging".

[0022] According to a preferred embodiment of the present invention, in steps A1-A2, the diameter of the carbon fiber is 7-10 μm and the length is 3-5 mm; the ultrasonic cleaning time is 30-40 min; the concentration of the concentrated nitric acid is 65-70%, the oxidation treatment time is 45-50 min, and the volume ratio of concentrated nitric acid to carbon fiber mass is (10-11):1; the drying temperature in the vacuum drying oven is 80-85°C, and the drying time is 6-8 h.

[0023] According to a preferred embodiment of the present invention, in step A3, the concentration of the aluminate coupling agent 2 is 2-3%; the ultrasonic dispersion time is 15-20 minutes; and the curing time is 30-40 minutes.

[0024] According to a preferred embodiment of the present invention, the preparation steps of the modified epoxy resin matrix include: B1, heating the epoxy resin to 80-85°C to melt it, adding nano-montmorillonite and stirring; B2, adding polyamide, DMP-30 and dibutyl phthalate, and vacuum degassing at 100-105°C.

[0025] According to a preferred embodiment of the present invention, the epoxy resin is purchased from Hongchang Electronic Materials Co., Ltd. as Model E-51.

[0026] According to a preferred embodiment of the present invention, the nano-montmorillonite is purchased from Zhejiang Fenghong New Materials Co., Ltd. as model MMT-20.

[0027] According to a preferred embodiment of the present invention, the polyamide is purchased from Suzhou Xingda Nylon Co., Ltd. and is a PA650 model.

[0028] According to a preferred embodiment of the present invention, the DMP-30 is purchased from Yuhai Aladdin Biochemical Technology Co., Ltd.

[0029] According to a preferred embodiment of the present invention, the dibutyl phthalate is purchased from Jinling Petrochemical Chemical Plant No. 2.

[0030] The curing, cross-linking, and network optimization of the modified epoxy resin matrix in this invention are the core guarantees of strength and toughness. After the epoxy resin (such as E-51) is heated to 80-85°C and melted, the epoxy groups (-CH(O)CH-) in its molecular chain are in a highly reactive state. The added nano-montmorillonite (particle size 20-50nm) is physically dispersed and embedded in the continuous epoxy resin phase through high-speed stirring (1200-1400rpm). The silanol (-Si-OH) groups on the surface of the lamellae form hydrogen bonds or weak covalent bonds with the epoxy groups, restricting the free movement of the epoxy molecular chains and initially improving the rigidity of the matrix. Polyamide 650 (an aliphatic polyamine with a matching epoxy value) is subsequently added as a curing agent. The primary (-NH2) and secondary (-NH-) amine groups in its molecules undergo a ring-opening addition reaction with the epoxy groups. The ring-opening of the epoxy groups (C-O bond cleavage) and the nucleophilic attack of the amino groups (N-H bond cleavage) alternate, forming a three-dimensional cross-linked network structure that imparts high strength to the matrix. DMP-30 (2,4,6-tris(dimethylaminomethyl)phenol) acts as a tertiary amine accelerator, activating the epoxy groups by providing lone pairs of electrons, reducing the reaction activation energy and accelerating the cross-linking process. This results in a denser and more uniform network structure, avoiding strength defects caused by insufficient cross-linking. Dibutyl phthalate (DBP) acts as a toughening agent. Its long-chain molecules (C6H4(COO(CH2)3CH3)2) can insert into the gaps of the cross-linked network, absorbing impact energy through chain segment sliding, inhibiting crack propagation, and balancing the rigidity and toughness of the matrix, thus avoiding the brittle fracture problem of traditional epoxy resins.

[0031] According to a preferred embodiment of the present invention, in step B1, the epoxy value of the epoxy resin is 0.51-0.54eq / 100g; the particle size of the nano-montmorillonite is 20-50nm, and the mass is 5-8% of the epoxy resin; the stirring speed is 1200-1400rpm, and the stirring time is 20-30min.

[0032] According to a preferred embodiment of the present invention, in step B2, the mass ratio of the polyamide to the epoxy resin is 1:(6-7), the amount of DMP-30 is 2-3% of the mass of the epoxy resin; the amount of dibutyl phthalate is 5-6% of the mass of the epoxy resin; the vacuum degassing time is 30-40 min, and the vacuum degree is ≤-0.09 MPa.

[0033] The synergistic effect of the nanofiller and functional additives in this invention further optimizes overall performance. The nano-montmorillonite's lamellar structure slows the penetration of corrosive media like oxygen and water molecules through a "barrier effect," and synergistically inhibits the oxidative degradation of epoxy resin with antioxidant 1010 (hindered phenol). The antioxidant captures free radicals (such as ROO·), blocking chain oxidation reactions and slowing material aging. Chopped glass fibers (0.5-1 mm in length) serve as a secondary reinforcement phase. The hydroxyl groups on their surface form hydrogen bonds with the epoxy resin, compensating for the carbon fiber's insufficient aspect ratio and enhancing the material's overall rigidity. The aluminate coupling agent's adsorption-like effect on the glass fiber surface further strengthens the interfacial bond between the glass fiber and the matrix.

[0034] The components in the present invention form a composite material system of "modified carbon fiber providing high modulus and load transfer, modified epoxy resin providing toughness energy dissipation and corrosion resistance, nanofillers and additives optimizing weather resistance" through the multiple effects of "interface reinforcement-network construction-synergistic toughening", so that the clamp can still maintain high strength, high toughness and long-term stability under complex working conditions such as high temperature, high pressure and corrosion.

[0035] The present invention also provides a method for processing the high-strength clamp, comprising the following steps:

[0036] S1, firstly mix the modified carbon fiber, chopped glass fiber and aluminate coupling agent 1 evenly, then add the modified epoxy resin matrix and antioxidant and stir to form a composite material premix;

[0037] S2. Place the premix into the clamp mold cavity preheated to 120-125°C. After closing the mold, maintain the pressure at 150-160°C and 12-15MPa to fully cure the composite material.

[0038] S3. After demoulding, the hoop blank is obtained, which is first annealed at 200-205℃, and then the surface is strengthened by shot peening. Finally, the annealed and shot peened hoop is machined to process bolt holes and anti-slip teeth.

[0039] According to a preferred embodiment of the present invention, in step S1, the mixing speed is 500-600 rpm, and the mixing time is 5-10 min; the stirring speed is 800-1000 rpm, and the stirring time is 10-20 min.

[0040] According to a preferred embodiment of the present invention, in step S2, the pressure holding time is 15-20 minutes.

[0041] According to a preferred embodiment of the present invention, in step S3, the annealing treatment time is 2-3 hours; the diameter of the shot in the shot peening process is 0.2-0.5 mm, the spraying pressure is 0.4-0.6 MPa, and the coverage is ≥90%.

[0042] The beneficial effects of the present invention are:

[0043] The high-strength clamp of the present invention has significantly improved its comprehensive performance through material modification and process optimization, effectively solving the performance shortcomings of traditional clamps under complex working conditions. Traditional clamps are mostly made of ordinary carbon steel or simple alloy materials, which are prone to deformation, breakage or rust in high temperature, high pressure or highly corrosive environments, and have insufficient toughness and are difficult to withstand impact or vibration loads. The present invention, through the synergistic effect of modified carbon fiber and modified epoxy resin matrix, combined with composite processing technology, makes the clamp have higher strength, toughness and weather resistance, can be used stably for a long time in extreme environments, and greatly extends its service life.

[0044] The combined modification of modified carbon fibers and modified epoxy resin matrices is key to performance improvement. After the modified carbon fibers are oxidized with concentrated nitric acid, polar functional groups containing hydroxyl and carboxyl groups are generated on the surface, increasing the number of chemical bonding sites with the matrix. Subsequent treatment with an aluminate coupling agent further improves the dispersion of the carbon fibers in the matrix, reduces interfacial stress concentration, and enables the carbon fibers and epoxy resin to form a more stable bonding interface, effectively improving the overall strength of the material. The uniform dispersion of nano-montmorillonite in the modified epoxy resin matrix enhances the toughness of the matrix. The synergistic effect of the toughening agent and accelerator balances strength and impact resistance, avoiding the fracture problem of traditional materials due to brittleness and making the clamp less susceptible to damage when subjected to vibration or impact loads.

[0045] The optimization of the processing technology further ensures the stable performance of the material properties. The compression molding process enables the composite material to solidify evenly under high temperature and high pressure, ensuring the density of the material structure; the annealing treatment effectively eliminates the internal stress generated during the molding process and reduces the risk of deformation in subsequent use; the shot peening process forms a dense oxide film on the surface through the impact of projectiles, which significantly improves the surface hardness and corrosion resistance and delays the occurrence of rust. The final product clamp has high dimensional accuracy, and the bolt holes, anti-slip teeth and other structures are precisely processed, with good installation matching. In actual applications, its tensile strength, impact strength and weather resistance are far superior to traditional clamps, and it can meet the reliable connection requirements of various complex working conditions such as high temperature, high pressure, and corrosion, with significant comprehensive performance advantages. DETAILED DESCRIPTION

[0046] The following specific implementation methods are only used to further illustrate the present application and should not be understood as limiting the scope of protection of the present application. Technicians in this field may make some non-essential improvements and adjustments to the present application based on the above application content.

[0047] 1. Implementation

[0048] Example 1

[0049] The raw materials were weighed by mass: 300 g of modified carbon fiber, 500 g of modified epoxy resin matrix, 120 g of chopped glass fiber, 8 g of antioxidant (model: 1010, purchased from BASF, analytical grade), and 12 g of aluminate coupling agent (model: DL-411-Al, purchased from Nanjing Shuguang Chemical, industrial grade). The specific steps are as follows: first, prepare modified carbon fiber, select T300 grade carbon fiber with a diameter of 7-10 μm (average diameter 8.5 μm) and a length of 3-5 mm (average length 4 mm) (purchased from Zhongfu Shenying Carbon Fiber Co., Ltd., model SYT49S), place it in a beaker and add acetone solution (analytical pure, concentration ≥99.5%, volume 10 times the mass of carbon fiber, i.e. 3000 mL), set ultrasonic cleaning machine (model: KQ-500DE, Kunshan Ultrasonic) power to 500 W, frequency 40 kHz, ultrasonic cleaning 35 min (stirring once every 10 min during the period), after cleaning is completed, rinse repeatedly with deionized water (resistivity ≥18.2 MΩ·cm) until the filtrate pH = 7, collect in a glass culture dish and dry; transfer the dried carbon fiber to a constant temperature drying oven (model: DHG-9070A, Shanghai Yiheng), set the temperature to 82 ° C preheating 10 min, prepare 68% ( A concentrated nitric acid solution (analytical grade, concentration 65-68%, volume 10.5 times the mass of the carbon fiber, i.e. 3150 mL) with a mass fraction of 1.5 g was poured into a polytetrafluoroethylene-lined reactor, and the carbon fiber was immersed in it, followed by magnetic stirring (speed 300 rpm) and oxidation treatment in a water bath (82 ± 1 ° C) for 48 min. After removal, it was rinsed with deionized water until neutral, and then transferred to a vacuum drying oven (model: DZF-6020, Shanghai Yiheng) at 83 ° C and vacuum ≤-0.09 MPa for 7 h; the dried carbon fiber was immersed in an anhydrous ethanol solution of an aluminate coupling agent (aluminate coupling agent (DL-411-Al) 12 g was dissolved in 588 g anhydrous ethanol, concentration 2%;), ultrasonically dispersed for 18 min (ultrasonic cleaning machine power 600 W), and after dispersion was completed, poured into a petri dish and placed in an oven (model: GZX-9070MBE, Shanghai Boxun) at 102 ° C for 35 min to obtain modified carbon fiber.Then, a modified epoxy resin matrix was prepared. 500 g of bisphenol A epoxy resin (purchased from Hongchang Electronic Materials Co., Ltd., model E-51) with an epoxy value of 0.52 eq / 100 g was placed in a beaker and heated in a water bath (model: HH-6, Jintan Liangyou) to 83 ° C and heated at 5 ° C / min until completely melted (transparent liquid). Nano-montmorillonite (purchased from Zhejiang Fenghong New Materials Co., Ltd., model MMT-20, particle size 20-50 nm, 25 g, accounting for 5% of the epoxy resin mass) was added and magnetically stirred (speed 1300 rpm, anchor stirring paddle, 316L stainless steel) for 25 min until uniformly dispersed. Polyamide (purchased from Suzhou Xingda Nylon Co., Ltd., model PA650, 76.9 g, with epoxy resin mass ratio of 1:6.5), DMP-30 (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., analytical grade, 12.5 g, epoxy resin mass 2.5%) and dibutyl phthalate (purchased from Jinling Petrochemical Chemical Plant No. 2, industrial grade, 27.5 g, epoxy resin mass 5.5%), continue stirring at 1000 rpm for 15 min (temperature 103 ± 2 ° C), transfer to a vacuum deaerator (model: ZK-500, Shanghai Keqi) at 103 ° C, vacuum degree -0.095 MPa for 35 min until there are no bubbles to obtain a modified epoxy resin matrix. Finally, high-strength hoop was processed: 300 g of modified carbon fiber, 120 g of chopped glass fiber (purchased from Jushi Group, model ECS301-H), 500 g of modified epoxy resin matrix, and 8 g of antioxidant were added to a high-speed mixer (model: SHR-100A, Zhangjiagang Yili), mixed at 550 rpm for 5 min and then at 850 rpm for 15 min until uniform; the premix was poured into a steel mold (45# steel, inner diameter φ200 mm × depth 50 mm, surface polishing Ra ≤ 0.8 μm) preheated to 122°C, and after the mold was closed, a hydraulic press (model: Y32-500, Zhejiang Forging Machine Tool) was pressurized at 152°C and 13 MPa for 18 min ( The blank was placed in an annealing furnace (model: RJX-45-12, Shanghai Keheng) at 202°C under nitrogen protection (flow rate 50mL / min), heated at 10°C / min for 2.5 hours, and then cooled with the furnace. A shot blasting machine (model: Q3210, Yancheng, Jiangsu) was used to spray 0.3mm steel shots (SKD11, HRC58-60) at 0.5MPa for 10 minutes (coverage rate ≥92%). A CNC machine tool (model: CK6140, Shenyang Machine Tool) was used to machine bolt holes (8mm in diameter, 15mm in depth) and anti-slip teeth (tooth height 2mm, tooth pitch 5mm) to finally obtain the high-strength clamp product.

[0050] Example 2

[0051] The preparation method is the same as that of Example 1, except that the following raw materials are weighed by mass: 350 g of modified carbon fiber, 450 g of modified epoxy resin matrix, 130 g of chopped glass fiber, 9 g of antioxidant, and 11 g of aluminate coupling agent. Preparation of modified carbon fiber: 350 g of carbon fiber (diameter 7-10 μm, length 3-5 mm) is ultrasonically cleaned with acetone for 38 min, oxidized with concentrated nitric acid (70% concentration, volume 3850 mL) at 85° C. for 50 min, rinsed with deionized water until neutral, and vacuum dried at 85° C. for 8 h. Preparation of modified epoxy resin matrix: 450g epoxy resin (epoxy value 0.54eq / 100g), melted at 85°C, added 36g nano-montmorillonite (8% of epoxy resin, 20-50nm), and stirred at 1400rpm for 30min; added polyamide (64.3g), DMP-30 (13.5g), and dibutyl phthalate (27g), stirred at 105°C for 20min; vacuum degassing at 105°C and -0.09MPa for 40min. Processing method: 350g modified carbon fiber, 130g chopped glass fiber, 450g modified epoxy resin matrix, 9g antioxidant, mixed at 500rpm for 5min, and then at 800rpm for 10min; preheated at 125℃, maintained at 160℃ and 15MPa for 20min; annealed at 205℃ for 3h, shot peening (shot 0.5mm, pressure 0.6MPa, coverage 95%), and machined bolt holes and anti-slip teeth.

[0052] Example 3

[0053] The preparation method is the same as that of Example 1, except that the following raw materials are weighed by mass: 250 g of modified carbon fiber, 550 g of modified epoxy resin matrix, 110 g of chopped glass fiber, 7 g of antioxidant, and 13 g of aluminate coupling agent. Preparation of modified carbon fiber: 250 g of carbon fiber (diameter 7-10 μm, length 3-5 mm) is ultrasonically cleaned with acetone for 32 min, oxidized with concentrated nitric acid (65% concentration, volume 2500 mL) at 80°C for 45 min, rinsed with deionized water until neutral, and vacuum dried at 80°C for 6 h. Preparation of modified epoxy resin matrix: 550g epoxy resin (epoxy value 0.51eq / 100g) was melted at 80°C, 27.5g nano-montmorillonite (5% of epoxy resin, 20-50nm) was added, and stirred at 1200rpm for 20min; polyamide (78.6g), DMP-30 (11g), and dibutyl phthalate (27.5g) were added, and stirred at 100°C for 10min; vacuum degassing was performed at 100°C and -0.09MPa for 30min. Processing method: 250g of modified carbon fiber, 110g of chopped glass fiber, 550g of modified epoxy resin matrix, and 7g of antioxidant, mixed at 600rpm for 10min and 1000rpm for 20min; preheated at 120℃, maintained at 150℃ and 12MPa for 15min; annealed at 200℃ for 2h, shot peening (shot 0.2mm, pressure 0.4MPa, coverage 90%), and machined bolt holes and anti-slip teeth.

[0054] Comparative Example 1

[0055] The preparation method is the same as that in Example 1, except that, compared with Example 1, only the concentrated nitric acid oxidation treatment (step A2) is omitted in the modified carbon fiber preparation step, and the carbon fiber is only washed with acetone (35 min) and vacuum dried at 83°C (7 h), and then directly immersed in the aluminate coupling agent solution for treatment.

[0056] Comparative Example 2

[0057] The preparation method is the same as that in Example 1, except that, compared with Example 1, nano-montmorillonite is omitted in the preparation step of the modified epoxy resin matrix (only 500 g of epoxy resin is added in step B1, without nano-montmorillonite).

[0058] Comparative Example 3

[0059] The preparation method is the same as that of Example 1, except that, compared with Example 1, only the shot peening process is omitted in the processing method (in step S3, only annealing at 202°C for 2.5h is performed without shot peening).

[0060] 2. Performance Testing

[0061] The high-strength clamps prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests according to the following method:

[0062] 1. Tensile strength test: Tested in accordance with GB / T 1040.2-2022, "Plastics—Determination of Tensile Properties—Part 2: Test Conditions for Molded and Extruded Plastics." An electronic universal testing machine (Instron 5967, USA) was used. Standard dumbbell-type specimens (gauge length 25 mm, width 4 mm, thickness 2 mm) were tested at a tensile rate of 2 mm / min. Five parallel specimens were tested per group, and the average value was calculated.

[0063] 2. Interface bonding strength test: A scanning electron microscope (SEM, model: SU8010, Hitachi) was used to observe the cross-sectional morphology of the composite material, and the bonding strength was evaluated by the debonding area ratio of the fiber-resin interface (debonding area ≤ 5% was excellent, 5%-15% was good, and >15% was poor). At the same time, a nanoindenter (model: TriboIndenter TI 950, Hysitron, USA) was used to test the interface shear strength with a loading force of 500 μN and a holding time of 10 s. The average value of 10 measuring points was taken.

[0064] 3. Thermal stability test: A thermogravimetric analyzer (TGA, model: TGA-50, Shimadzu) was used. The test conditions were nitrogen atmosphere (flow rate 50 mL / min), heating rate 10°C / min, temperature range 30-800°C, and the initial decomposition temperature (temperature at 5% weight loss) and maximum decomposition temperature (DTG curve peak temperature) were recorded.

[0065] 4. Surface hardness test: Use Vickers hardness tester (model: HV-1000Z, Shanghai Shangcai), load 10kgf (about 98N), holding time 15s, select 5 points evenly on the surface of the clamp for testing, and take the average value.

[0066] 5. Fatigue resistance test: A high-frequency fatigue testing machine (model: PLD-500, Sichuan Institute of Materials and Testing) was used to apply cyclic load (stress ratio R = 0.1, frequency 50 Hz), and the number of cycles to fracture (Nf) was recorded.

[0067] 6. Surface residual stress test: X-ray diffractometer (XRD, model: Bruker D8 Advance) was used, using Cr target 2θ scanning range 10°-90°, step size 0.02°, according to sin 2 The surface residual stress was calculated by the ψ method (σ = K·(E / (2(1+ν)))·cotθ·Δ(2θ) / tanθ, where K is the stress constant, E is the elastic modulus, and ν is the Poisson's ratio).

[0068] 7. Performance test results:

[0069] Table 1: Performance test results of various embodiments and comparative examples

[0070]

[0071] As can be seen from Table 1, the comparative analysis of Examples 1-3 of the present invention with Comparative Examples 1-3 significantly verifies its effectiveness in solving the problems of easy deformation and fracture, corrosion and rust, insufficient toughness, weak interface bonding, and poor weather resistance of traditional clamps under high temperature and high pressure. From the perspective of tensile strength, Example 1 (1320MPa) far exceeds Comparative Example 1 (980MPa). Because Comparative Example 1 did not perform concentrated nitric acid oxidation treatment on the carbon fiber, the surface polar functional groups were missing, and the aluminate coupling agent could not effectively bind, resulting in severe interface debonding (25% debonding area) and low load transfer efficiency. In contrast, Example 1 introduced polar functional groups such as hydroxyl and carboxyl groups on the surface of the carbon fiber through concentrated nitric acid oxidation, and combined with the aluminate coupling agent to enhance the interface bonding with the epoxy resin (interface shear strength 75-85MPa), significantly improving the overall strength of the composite material. In Comparative Example 2, due to the lack of nano-montmorillonite, the interface between the epoxy resin matrix and the fiber has insufficient lubricity, the difference in thermal expansion coefficient increases, and it is prone to stress concentration fracture at high temperatures (tensile strength 1150 MPa). At the same time, the initial thermal decomposition temperature is reduced to 315°C (345°C in Example 1), and the heat resistance is reduced. The addition of 5% nano-montmorillonite in Example 1 effectively fills the defects of the resin matrix, reduces the interfacial stress, and improves the dimensional stability at high temperatures. In Comparative Example 3, due to the lack of shot peening treatment, the surface residual compressive stress is only -200 MPa (-350 MPa in Example 1), which cannot effectively inhibit crack propagation, and the fatigue resistance number is reduced to 8.0×10 5 times (Example 1 is 1.2×10 6 times), which is prone to brittle fracture under cyclic loads; while the shot peening process of Example 1 forms a uniform compressive stress layer on the surface, which significantly delays crack initiation and improves fatigue toughness. In terms of weather resistance, the initial decomposition temperature (345°C) and the maximum decomposition temperature (480°C) of Example 1 are both higher than those of Comparative Example 2 (315°C, 445°C), indicating that the addition of nano-montmorillonite enhances the thermal stability of the matrix and reduces thermal degradation at high temperatures. Taken together, Examples 1-3 comprehensively optimize the high-temperature strength, corrosion resistance, toughness and interface bonding performance of the clamp by regulating the surface polarity of the modified carbon fiber (solving weak interface bonding), strengthening the matrix of nano-montmorillonite and regulating the residual stress of the shot peening process (improving fatigue resistance), effectively solving the problems of deformation, fracture, rust and brittle fracture of traditional clamps in complex environments, and achieving the goal of preparing high-performance clamps.

[0072] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A high-strength clamp, characterized in that: In terms of mass percentage, the raw materials include: Modified carbon fiber: 25-35%; Modified epoxy resin matrix: 45-55%; Chopped glass fiber: 10-15%; Antioxidants: 0.5-1%; Aluminate coupling agent 1: 0.5-1%; The modified carbon fiber preparation method comprises the following steps: A1, placing the carbon fiber in an acetone solution for ultrasonic cleaning to remove surface oil stains; A2, then transferring the carbon fiber to a constant temperature box and oxidizing it with concentrated nitric acid at 80-85°C; after taking it out, repeatedly rinsing it with deionized water until it is neutral, and placing it in a vacuum drying oven for drying; A3, finally immersing the dried carbon fiber in an anhydrous ethanol solution of an aluminate coupling agent 2, ultrasonically dispersing it, and curing it at 100-105°C after taking it out.

2. The high-strength clamp according to claim 1, characterized in that: In steps A1-A2, the diameter of the carbon fiber is 7-10 μm and the length is 3-5 mm; the ultrasonic cleaning time is 30-40 min; the concentration of the concentrated nitric acid is 65-70%, the oxidation treatment time is 45-50 min, and the volume ratio of concentrated nitric acid to carbon fiber mass is (10-11):1; the drying temperature in the vacuum drying oven is 80-85° C., and the drying time is 6-8 h.

3. The high-strength clamp according to claim 1, characterized in that: In step A3, the concentration of the aluminate coupling agent 2 is 2-3%; the ultrasonic dispersion time is 15-20 minutes; and the curing time is 30-40 minutes.

4. The high-strength clamp according to claim 1, characterized in that: The preparation steps of the modified epoxy resin matrix include: B1, heating the epoxy resin to 80-85°C to melt it, adding nano-montmorillonite and stirring; B2, adding polyamide, 2,4,6-tris(dimethylaminomethyl)phenol and dibutyl phthalate, and vacuum degassing at 100-105°C.

5. The high-strength clamp according to claim 4, characterized in that: In step B1, the epoxy value of the epoxy resin is 0.51-0.54 eq / 100 g; the particle size of the nano-montmorillonite is 20-50 nm, and the mass is 5-8% of the epoxy resin; the stirring speed is 1200-1400 rpm, and the stirring time is 20-30 min.

6. The high-strength clamp according to claim 4, characterized in that: In step B2, the mass ratio of the polyamide to the epoxy resin is 1:(6-7), the amount of the DMP-30 is 2-3% of the mass of the epoxy resin; the amount of the dibutyl phthalate is 5-6% of the mass of the epoxy resin; the vacuum degassing time is 30-40 minutes, and the vacuum degree is ≤-0.09 MPa.

7. A method for processing a high-strength clamp according to any one of claims 1 to 6, characterized in that the steps include: S1, firstly mix the modified carbon fiber, chopped glass fiber and aluminate coupling agent 1 evenly, then add the modified epoxy resin matrix and antioxidant and stir to form a composite material premix; S2. Place the premix into the hoop mold cavity preheated to 120-125°C, close the mold, and maintain the pressure at 150-160°C and 12-15MPa to solidify the composite material; S3. After demoulding, the hoop blank is obtained, which is first annealed at 200-205℃, and then the surface is strengthened by shot peening. Finally, the annealed and shot peened hoop is machined to process bolt holes and anti-slip teeth.

8. The processing method according to claim 7, characterized in that: In step S1, the mixing speed is 500-600 rpm, and the mixing time is 5-10 min; the stirring speed is 800-1000 rpm, and the stirring time is 10-20 min.

9. The processing method according to claim 7, characterized in that: In step S2, the pressure holding time is 15-20 minutes.

10. The processing method according to claim 7, characterized in that: In step S3, the annealing treatment time is 2-3 hours; the diameter of the shot in the shot peening process is 0.2-0.5 mm, the spraying pressure is 0.4-0.6 MPa, and the coverage is ≥90%.

Images