Preparation method of carbon-based composite material for wheel lightweight

Abstract

The invention discloses a carbon-based composite material for wheel lightweight and a preparation method and application thereof, and belongs to the field of automobile lightweight materials. The composite material is prepared from graphite powder, coconut shell powder, calcium sulfate whiskers, a phenolic resin aqueous solution, medium-temperature coal pitch, refined naphthalene powder and polystyrene spheres according to a specific ratio through low-temperature crushing, graded mixing, cold press molding, stepped drying and carbonization processes. The carbon-based composite material is low in density, high in high-temperature strength, integrated in function and controllable in cost.

Description

Technical Field

[0001] This invention relates to the field of automotive lightweight materials technology, and specifically proposes a method for preparing carbon-based composite materials for lightweight wheels. Background Technology

[0002] As a critical safety component, automotive wheels must simultaneously meet requirements for high strength, fatigue resistance, and lightweight design. With the increasingly stringent energy consumption demands of new energy vehicles, lightweight wheel design has become a core research and development direction in the industry. Among existing lightweight technologies, the "retained core" solution is gradually replacing the traditional removal-type sand core due to its significant weight reduction effect without altering the wheel's shape.

[0003] However, existing retained core materials suffer from the following technical bottlenecks: The contradiction between lightweighting and strength: Inorganic vermiculite-based cores have a high density, resulting in limited lightweighting effects; carbon fiber-based cores, although low in density, are expensive and lack sufficient flexural strength to withstand the impact of aluminum alloy molten casting.

[0004] Insufficient high-temperature stability: Some organic composite cores are prone to decomposition and collapse under the action of molten aluminum alloy at 700℃, resulting in defects such as porosity and inclusions in the wheel hub.

[0005] The existing core is only used as a filler and does not take into account the heat conduction and vibration reduction requirements of the wheel hub during service, thus failing to solve problems such as high temperature accumulation during braking and road vibration noise.

[0006] Traditional retainable cores require specialized molding equipment, have low compatibility with existing wheel hub casting lines, and are difficult to mass-produce.

[0007] Therefore, developing a core material with low density, high high-temperature strength, integrated functions, and controllable cost has become the key to solving the bottleneck of lightweight wheel hubs. Summary of the Invention

[0008] In view of this, and in response to the shortcomings of existing wheel cores such as "the contradiction between lightweight and strength, insufficient high-temperature stability, single function, and high cost", this invention proposes a carbon-based composite material for lightweight wheels and its preparation method.

[0009] The technical solution of this invention is implemented as follows: This invention provides a carbon-based composite material for lightweight wheels, the raw materials of which, by weight, include: 90-110 parts of 100-mesh graphite powder: Provides a thermally conductive framework, suppresses thermal deformation at high temperatures, and ensures the dimensional stability of the material; 45-55 parts of 220 mesh coconut shell powder: After carbonization, it forms a porous carbon skeleton, which contributes to the lightweight (porosity 40-50%), while its natural fibrous structure improves the toughness of the material. 45-55 parts of medium-temperature coal tar pitch: as the main binder in the high-temperature stage, it forms a continuous carbon binder phase after carbonization, which enhances the overall strength of the material. 20-30 parts of 50% phenolic resin aqueous solution: as a low-temperature temporary adhesive, it fixes the material form during the molding stage and gradually decomposes without residue at high temperatures; 2.5-3.5 parts of 120-mesh refined naphthalene powder: It is easily volatile at room temperature, forming micron-level exhaust channels to avoid porosity caused by gas accumulation during the casting process; 0.8-1.2 parts of 0.5-1mm polystyrene spheres: shrink at medium temperature and carbonize at high temperature, working synergistically with refined naphthalene powder to build interconnected pores and improve exhaust efficiency; 4-6 parts of calcium sulfate whiskers: They fill the strength defects of the porous structure through the "bridging effect", improve the flexural and compressive strength of the material, and their high temperature resistance ensures stable performance at 700℃.

[0010] In some embodiments, the preparation method of the above-mentioned carbon-based composite material includes the following steps: Pretreatment: Medium-temperature coal tar pitch is crushed to 180 mesh at ≤10℃ to prevent the coal tar pitch from softening and clumping due to excessive temperature. It is then mixed with 100 mesh graphite powder and calcium sulfate whiskers, dry-mixed for 30 minutes, and then passed through a 46 mesh sieve to ensure uniform dispersion of inorganic aggregates. Mixed molding materials: (1) Add 50% phenolic resin aqueous solution to the pretreated mixture and wet mix for 15 minutes to make the resin evenly coat the surface of the aggregate. (2) Add 0.5-1mm polystyrene balls in sequence. The polystyrene balls can be added intermittently to avoid agglomeration. Mix for 5 minutes. Add 120-mesh refined naphthalene powder and mix for 3 minutes. Add 220-mesh coconut shell powder and mix for 15 minutes until the material is evenly dry and wet and has a consistent color. Pass through a 30-mesh sieve for later use. Cold pressing: The mixed molding material is poured into a mold coated with a release agent and pressed under a pressure of 80-100 MPa, controlling the molding density to be 1.18-1.22 g / cm³. 3 After holding the pressure for 30-60 seconds, the mold is removed to obtain the blank; Step drying: Place the blank in a drying oven and dry it according to the following curve: room temperature → 60℃ (60 minutes) → 80℃ (60 minutes) → 110℃ (90 minutes), and keep it at the temperature for 60 minutes. Gradual temperature increase avoids rapid evaporation of moisture, which may cause the blank to crack. Inert gas protected carbonization: Under nitrogen flow rate of 5-10 L / min, heat treatment is performed according to the following curve: The temperature range is as follows: room temperature → 100℃ (30 minutes) → 200℃ (120 minutes) → 400℃ (240 minutes) → 500℃ (60 minutes) → 800℃ (300 minutes) → 900℃ (300 minutes), and held at that temperature for 60 minutes. The heating rate in the 500-800℃ stage is 1±0.2℃ / min to ensure slow carbonization of the organic components and avoid violent decomposition that could cause cracks. The heating rate in the 800-900℃ stage is 0.33±0.05℃ / min to promote uniform distribution of the carbon phase and improve strength.

[0011] In some embodiments, carbonized carbon-based composite material is used as the core and permanently retained in the mechanical redundancy area of ​​the wheel hub spokes or rim. The stress value in this area is <50MPa according to finite element analysis, and the core volume accounts for 15-30% of the total volume of the wheel hub. During the casting process, the core and the aluminum alloy body form a metallurgical bonding interface, and an Al4C3 transition layer with a thickness of 0.5-2μm is generated at the interface to improve the bonding strength between the core and the aluminum body. The core porosity is 60-70%, the pore size distribution is 0.1-0.5mm, and the pore penetration rate is >90%, ensuring smooth venting and avoiding porosity defects.

[0012] Graphite powder (100 mesh) serves as a continuous thermally conductive framework, providing dimensional stability at high temperatures, and its layered structure can disperse stress. After carbonization, coconut shell powder (220 mesh) forms a three-dimensional interconnected porous structure, which is the core contribution to lightweighting. At the same time, its natural fibrous residual structure can enhance the toughness of the graphite skeleton.

[0013] The two work synergistically: using graphite powder alone will result in excessive density, while using coconut shell powder alone will not be able to withstand the impact of molten aluminum due to the lack of a rigid framework. This application achieves a balance between rigidity and lightweight by using a ratio of 1:0.5.

[0014] While the porous structure of coconut shell powder reduces weight, it also reduces strength. Calcium sulfate whiskers embed themselves into the pore walls of the porous carbon skeleton through the "bridging effect," filling structural defects and improving the compressive strength at 700℃. The high-temperature resistance of whiskers ensures that they do not soften in molten aluminum at 700℃, forming an "inorganic-organic" composite reinforcement system with the carbon skeleton, thus avoiding the sharp drop in strength caused by the high-temperature decomposition of traditional organic reinforcing agents.

[0015] Low temperature stage: 50% phenolic resin aqueous solution is used as a temporary adhesive to quickly fix the material form through hydrogen bonding, solving the problem of insufficient viscosity of coal tar pitch at room temperature. High-temperature stage: Phenolic resin gradually decomposes (300-500℃), while medium-temperature coal tar pitch softens and carbonizes simultaneously (500-900℃), forming a continuous carbon binder phase that firmly bonds all components together.

[0016] The two work together to overcome the contradiction of "easy dispersal at low temperatures or failure at high temperatures" of a single adhesive, ensuring structural stability throughout the entire lifecycle from molding to service.

[0017] Micron-level channels: 120-mesh refined naphthalene powder volatilizes during the drying stage, forming micron-level channels with a diameter of 5-10μm, and expelling low-temperature volatiles; Millimeter-scale channels: 0.5-1mm polystyrene spheres shrink at medium temperature (200-400℃) and carbonize at high temperature (500-800℃) to form millimeter channels with a diameter of 0.1-0.5mm, which discharge the high-temperature cracked gas of coconut shell powder and coal tar pitch; The two work together: naphthalene powder alone cannot exhaust gas from the high-temperature thick-walled area, and polystyrene balls alone are insufficient for low-temperature exhaust. The graded design reduces the gas generation to 8 mL / g, avoiding wheel hub porosity defects.

[0018] The present invention has the following advantages over the prior art: Synergistic effect of lightweight and strength: bulk density ≤0.8g / cm³ 3 The compressive strength at 700℃ is >5MPa, and the flexural strength is >2MPa, which meets the mechanical requirements of the retained core. Excellent high-temperature stability: After carbonization at 900℃, the material’s high-temperature resistance is significantly improved. It does not collapse or deform when aluminum alloy liquid is poured at 700℃, solving the problem of high-temperature failure of traditional organic cores. High process adaptability: The preparation process does not require special equipment and can be adapted to existing wheel casting production lines. Cold pressing and stepped carbonization processes ensure material consistency and are suitable for large-scale mass production. Functional integration and cost advantages: Graphite powder gives the material a thermal conductivity of 20 W / m·K, which can quickly dissipate the heat generated by braking and reduce the wheel hub temperature by 30-40°C. The porous structure can absorb road vibrations of 30-50Hz and reduce in-vehicle noise by 2-3dB. With material costs of only 10 yuan / kg, the cost of a single wheel hub is reduced by 184 yuan, resulting in significant economic benefits. Attached Figure Description

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a diagram showing the filling position of the carbon-based composite material of the present invention in the wheel hub (green area). Detailed Implementation

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this invention pertain. If any definition stated in this section is contrary to or otherwise inconsistent with a definition stated in a patent, patent application, published patent application, or other publication incorporated herein by reference, the definitions listed here shall prevail over those incorporated herein by reference.

[0023] Unless otherwise specified, the methods used in the following embodiments are conventional methods. Unless otherwise specified, the materials, reagents, and instruments used are conventional materials, reagents, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0024] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range. In this specification and claims, range definitions may be combined and / or interchanged, unless otherwise stated, these ranges include all subranges contained therein.

[0025] Example 1 Raw material composition (parts by weight):

[0026] 100 parts of 100-mesh graphite powder, 50 parts of 220-mesh coconut shell powder, 50 parts of medium-temperature coal tar pitch (softening point 80℃), 25 parts of 50% phenolic resin aqueous solution, 3 parts of 120-mesh refined naphthalene powder, 1 part of 0.5-1mm polystyrene spheres, and 5 parts of calcium sulfate whiskers (length-to-diameter ratio 40:1).

[0027] Preparation method: Coal tar pitch is pulverized to 180 mesh at 8℃, dry-mixed with graphite powder and calcium sulfate whiskers for 30 minutes, and then passed through a 46-mesh sieve. Add phenolic resin aqueous solution and wet mix for 15 minutes, then add polystyrene balls and mix for 5 minutes, naphthalene powder and mix for 3 minutes, and coconut shell powder and mix for 15 minutes in sequence, and then pass through a 30-mesh sieve; Cold pressing: pressure 90MPa, molding density 1.2g / cm³ 3 Hold pressure for 45 seconds; Step drying: 25℃→60℃ (60min)→80℃ (60min)→110℃ (90min), keep at 110℃ for 60min; Carbonization: Nitrogen flow rate 8L / min, heating curve 25℃→100℃(30min)→200℃(120min)→400℃(240min)→500℃(60min)→800℃(300min)→900℃(300min), hold for 60min, heating rate 1℃ / min from 500-800℃, heating rate 0.33℃ / min from 800-900℃.

[0028] Performance tests: bulk density 0.78 g / cm³, compressive strength at 700℃ 8.2 MPa, flexural strength 2.5 MPa, gas evolution 8 mL / g, and porosity 92%.

[0029] Example 2 Raw material composition (parts by weight):

[0030] 90 parts of 100-mesh graphite powder, 45 parts of 220-mesh coconut shell powder, 45 parts of medium-temperature coal tar pitch (softening point 80℃), 20 parts of 50% phenolic resin aqueous solution, 2.5 parts of 120-mesh refined naphthalene powder, 0.8 parts of 0.5-1mm polystyrene spheres, and 4 parts of calcium sulfate whiskers (length-to-diameter ratio 40:1).

[0031] Preparation method: Coal tar pitch is pulverized to 180 mesh at 8℃, dry-mixed with graphite powder and calcium sulfate whiskers for 30 minutes, and then passed through a 46-mesh sieve. Add phenolic resin aqueous solution and wet mix for 15 minutes, then add polystyrene balls and mix for 5 minutes, naphthalene powder and mix for 3 minutes, and coconut shell powder and mix for 15 minutes in sequence, and then pass through a 30-mesh sieve; Cold pressing: pressure 80MPa, molding density 1.2g / cm³ 3 Hold pressure for 45 seconds; Step drying: 25℃→60℃ (60min)→80℃ (60min)→110℃ (90min), keep at 110℃ for 60min; Carbonization: Nitrogen flow rate 8L / min, heating curve 25℃→100℃(30min)→200℃(120min)→400℃(240min)→500℃(60min)→800℃(300min)→900℃(300min), hold for 60min, heating rate 1℃ / min from 500-800℃, heating rate 0.33℃ / min from 800-900℃.

[0032] Performance tests: bulk density 0.76 g / cm³, compressive strength at 700℃ 5.8 MPa, flexural strength 2.1 MPa, gas evolution 9 mL / g, and porosity 90%.

[0033] Example 3 Raw material composition (parts by weight):

[0034] 110 parts of 100-mesh graphite powder, 55 parts of 220-mesh coconut shell powder, 55 parts of medium-temperature coal tar pitch (softening point 80℃), 30 parts of 50% phenolic resin aqueous solution, 3.5 parts of 120-mesh refined naphthalene powder, 1.2 parts of 0.5-1mm polystyrene spheres, and 6 parts of calcium sulfate whiskers (length-to-diameter ratio 40:1).

[0035] Preparation method: Coal tar pitch is pulverized to 180 mesh at 8℃, dry-mixed with graphite powder and calcium sulfate whiskers for 30 minutes, and then passed through a 46-mesh sieve. Add phenolic resin aqueous solution and wet mix for 15 minutes, then add polystyrene balls and mix for 5 minutes, naphthalene powder and mix for 3 minutes, and coconut shell powder and mix for 15 minutes in sequence, and then pass through a 30-mesh sieve; Cold pressing: pressure 100MPa, molding density 1.2g / cm³ 3 Hold pressure for 45 seconds; Step drying: 25℃→60℃ (60min)→80℃ (60min)→110℃ (90min), keep at 110℃ for 60min; Carbonization: Nitrogen flow rate 8L / min, heating curve 25℃→100℃(30min)→200℃(120min)→400℃(240min)→500℃(60min)→800℃(300min)→900℃(300min), hold for 60min, heating rate 1℃ / min from 500-800℃, heating rate 0.33℃ / min from 800-900℃.

[0036] Performance tests: bulk density 0.80 g / cm³, compressive strength at 700℃ 9.5 MPa, flexural strength 2.8 MPa, gas evolution 7 mL / g, and porosity 93%.

[0037] Comparative Example 1 Raw material composition (parts by weight): Expanded vermiculite (80 mesh, bulk density 0.3-0.4 g / cm³) 3 60 parts (SiO2 content 45%); 30 parts of aluminate cement (grade 42.5, initial setting time ≤ 45 min); 10 parts of ceramic fiber (3-5 mm in length, Al2O3 content ≥45%); 15 parts water (deionized water) (for adjusting consistency).

[0038] 2. Preparation process: (1) Dry mix expanded vermiculite, aluminate cement and ceramic fiber for 20 minutes, then add deionized water and wet mix for 10 minutes until it becomes a paste; (2) Pour into the mold (same specifications as in the example), and demold after natural curing for 24 hours; (3) Dry at 80℃ for 4 hours and dry at 120℃ for 2 hours to obtain vermiculite-based core.

[0039] 3. Performance testing method (consistent with the example): Bulk density: water displacement method (GB / T2997-2000); Compressive strength at 700℃: The test was conducted using a universal testing machine (model WDW-100), heated to 700℃ in a muffle furnace and held for 30 minutes, and then tested according to GB / T17671-1999. Gas generation: The water displacement method was used to collect the gas volume generated within 10 minutes by weighing 5g of sample and placing it in molten aluminum at 700℃. Pore ​​penetration rate: tested by mercury porosimetry (AutoPoreIV9500).

[0040] 4. Performance Results: Bulk density 1.32 g / cm³ 3 The compressive strength at 700℃ is 3.1MPa, the gas generation is 25.6mL / g, the pore penetration rate is 65% (there are many non-penetrating pores, resulting in poor gas expulsion), and the material cost is 15.2 yuan / kg (including raw materials and curing energy consumption).

[0041] Comparative Example 2 Raw material composition (parts by weight): 30 parts of short-cut carbon fiber (6mm in length, 7μm in diameter, tensile strength 3000MPa); 65 parts of epoxy resin (E-51, epoxy value 0.48-0.54 eq / 100g); 65 parts of curing agent (polyamide 650, with a mass ratio of 1:1 to epoxy resin); 1 part of coupling agent (KH-550).

[0042] 2. Preparation process: (1) The carbon fiber was treated with a coupling agent (soaked in 5% KH-550 ethanol solution for 1 hour and dried at 80°C). (2) Mix with epoxy resin and curing agent, and stir in a planetary mixer for 30 minutes (1000 rpm). (3) Pour into a mold and cure at 10MPa pressure and 80℃ for 2 hours to obtain a carbon fiber core.

[0043] 3. Performance testing method (consistent with the example): Bulk density: by displacement method; 700℃ compressive strength: First test the room temperature strength (12.5MPa), then test after holding at 700℃ for 30 minutes; Gas output: Same as comparative example 1; Interface bonding strength: The bonding strength with aluminum alloy was tested by shear test (GB / T15576-2008).

[0044] 4. Performance Results: Bulk density 1.15 g / cm³ 3 It has a compressive strength of 6.5 MPa at 700℃, a gas emission of 12.3 mL / g, a shear strength at the interface with aluminum alloy of 1.8 MPa, and a material cost of 205 yuan / kg.

[0045] Comparative Example 3 Raw material composition (parts by weight): 150 parts of 100-mesh graphite powder; 50 parts of medium-temperature coal tar pitch; 30 parts of 50% phenolic resin aqueous solution (excluding coconut shell powder, calcium sulfate whiskers, refined naphthalene powder, and polystyrene balls).

[0046] 3. Preparation process: Same as in Example 1.

[0047] 4. Performance Results: Bulk density 1.42 g / cm³ 3 The compressive strength at 700℃ is 4.2MPa, and the gas emission is 28mL / g, proving that the balance of "lightweight-strength-gas emission" cannot be achieved without the key components of this application.

[0048] Comparative Example 4 This comparative example is based on Example 1, except that the coal tar pitch pulverizing temperature is changed to 20°C, and other conditions are the same as in Example 1.

[0049] Performance test results: Bulk density: 0.85 g / cm³ 3 Compressive strength at 700℃: 6.5MPa Gas production (700℃): 12mL / g Comparative Example 5 This comparative example is based on Example 1, except that the heating rate of 500-800℃ was adjusted to 2℃ / min, and other conditions were the same as in Example 1.

[0050] Performance test results: Bulk density: 0.79 g / cm³ 3 Compressive strength at 700℃: 4.2 MPa Gas production (700℃): 15mL / g Comparative Example 6 Raw material composition (parts by weight): 100 parts of 100-mesh graphite powder 50 parts of 220 mesh coconut shell powder 50 parts of medium-temperature coal tar pitch 5 parts of calcium sulfate whiskers Missing: refined naphthalene powder, polystyrene balls, phenolic resin aqueous solution Process steps: Graphite powder, coal tar pitch, coconut shell powder, and calcium sulfate whiskers were directly mixed without using a graded bonding process.

[0051] Cold pressing pressure is 80MPa, and pressure is held for 30 seconds.

[0052] Carbonization treatment: directly heat to 900℃ at 5℃ / min.

[0053] Performance test results: Bulk density: 0.82 g / cm³ 3 Compressive strength at 700℃: 5.1 MPa Gas production (700℃): 32mL / g Comparative Example 7 Raw material composition (parts by weight): 100 parts of 100-mesh graphite powder, 50 parts of 220-mesh coconut shell powder, 5 parts of calcium sulfate whiskers, and 50 parts of medium-temperature coal tar pitch. Preparation process: (1) Dry mix graphite powder, coconut shell powder, calcium sulfate whiskers and coal tar pitch directly for 30 minutes; (2) Cold pressing: 80MPa pressure, holding pressure for 30 seconds; (3) Carbonization: directly increase the temperature to 900℃ at 3℃ / min.

[0054] Performance test results: Bulk density: 0.85 g / cm³ 3 ; Compressive strength at 700℃: 4.8 MPa; Gas production: 42 mL / g; Defect: Cracking occurs during high-temperature carbonization.

[0055] Comparative Example 8 Raw material composition (parts by weight): 100 parts of 100-mesh graphite powder, 50 parts of 220-mesh coconut shell powder, 5 parts of calcium sulfate whiskers, 25 parts of 50% phenolic resin aqueous solution, and 3 parts of 120-mesh refined naphthalene powder.

[0056] Preparation process: (1) The phenolic resin aqueous solution is wet-mixed with all components; (2) Cold pressing: 90MPa, holding pressure for 45 seconds; (3) Carbonization after drying: 500-800℃ heating rate 2℃ / min.

[0057] Performance test results: Bulk density: 0.82 g / cm³ 3 ; Compressive strength at 700℃: 3.5 MPa; Gas production: 28 mL / g; Defect: Core collapses at high temperatures.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A carbon-based composite material for lightweight wheels, characterized in that, By weight, the raw materials include: 90-110 parts of 100-mesh graphite powder 45-55 parts of 220-mesh coconut shell 45-55 parts of medium-temperature coal tar pitch 20-30 parts of 50% phenolic resin aqueous solution 2.5-3.5 parts of 120-mesh refined naphthalene powder 0.8-1.2 parts of 0.5-1mm polystyrene spheres 4-6 parts of calcium sulfate whiskers.

2. The carbon-based composite material for lightweight wheels as described in claim 1, characterized in that, The mass ratio of coconut shell powder to polystyrene balls is (45-55):(0.8-1.2).

3. The method for preparing the carbon-based composite material for lightweight wheels according to claim 1 or 2, characterized in that, Includes the following steps: (1) Medium-temperature coal tar pitch is pulverized to 180 mesh at ≤10℃ and mixed with graphite powder and calcium sulfate whiskers and passed through a 46 mesh sieve; (2) Add phenolic resin liquid to the material in step (1) and mix for 15 minutes. Then add polystyrene balls and mix for 5 minutes, naphthalene powder and mix for 3 minutes, and coconut shell powder and mix for 15 minutes. Then pass through a 30-mesh sieve. (3) Compression molding density: 1.18-1.22 g / cm³ 3 The blank.

4. The preparation method according to claim 3, characterized in that, The cold pressing pressure in step (3) is 80-100MPa, and the holding time is 30-60 seconds.

5. The preparation method according to claim 3, characterized in that, Also includes: (4) Step drying: Heat the blank from room temperature to 60°C for 60 min, then from 60°C to 80°C for 60 min, then from 80°C to 110°C for 90 min, and then keep at 110°C for 60 min; (5) Carbonization at N2 flow rate of 5-10 L / min: 30 min at room temperature to 100℃, 120 min from 100℃ to 200℃, 240 min from 200℃ to 400℃, 60 min from 400℃ to 500℃, 300 min from 500℃ to 800℃, 300 min from 800℃ to 900℃, and then hold at 900℃ for 60 min.

6. The preparation method according to claim 5, characterized in that, The heating rate in the 500-800℃ stage is 1±0.2℃ / min, and the heating rate in the 800-900℃ stage is 0.33±0.05℃ / min.

7. A lightweight wheel hub, characterized in that, The wheel includes the carbon-based composite material for lightweighting as described in claim 1 or 2, wherein the carbon-based composite material is permanently retained in the mechanical redundancy area of ​​the wheel hub spokes or rim, and the volume of the carbon-based composite material accounts for 15-30% of the total volume of the wheel hub.

8. The lightweight wheel hub as described in claim 7, characterized in that, The mechanical redundancy region is the area with stress value <50MPa in finite element analysis, and the carbon-based composite material and the aluminum alloy interface form an Al4C3 transition layer with a thickness of 0.5-2μm.

9. The lightweight wheel hub as described in claim 7, characterized in that, The carbon-based composite material has a porosity of 60-70%, a pore size distribution of 0.1-0.5 mm, and a pore penetration rate of >90%.

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