Lightweight wear-resistant automobile gear made of novel composite material

Abstract

The invention relates to a light wear-resistant automobile gear made of a novel composite material, belongs to the technical field of automobile new materials, and aims to solve the problems that the automobile gear is an important part of an automobile power transmission system, and is generally made of 45 # steel, and the steel gear is heavy and cannot be used as a wear-resistant gear; according to the invention, the carbon (graphite) short fibers and the metal aluminum alloy are creatively used as raw materials, and through special processes such as mixing, wax-doping granulation, compression molding, dewaxing hot isostatic pressing sintering and the like, the carbon (graphite) short fibers and the metal aluminum alloy are prepared. The light wear-resistant automobile gear has the advantages of being high in strength and modulus and good in wear resistance and is light in weight which is about 30% of the weight of a 45 # steel gear, the weight is reduced by about 65% with the same gear size and parameter, the light wear-resistant automobile gear is more wear-resistant than the 45 # steel gear, and the service life of the light wear-resistant automobile gear is prolonged. The requirement for automobile lightweight improvement is well met, and the automobile lightweight technical level is improved.

Description

I. Technical Field

[0001] This invention, "A Lightweight and Wear-Resistant Automotive Gear Manufactured Using a Novel Composite Material," belongs to the field of new automotive materials technology. II. Technical Background

[0002] In 2023, my country's automobile production and sales both exceeded 30 million vehicles, indicating a huge market potential for automobile products.

[0003] Studies have shown that for every 100 kg reduction in the weight of a passenger car, 0.39 liters of gasoline can be saved per 100 kilometers; a 10% reduction in vehicle weight can reduce fuel consumption by 6% to 8% and emissions by 4%. Reducing vehicle weight and applying new composite lightweight materials are the main research goals and objectives of automotive technology.

[0004] The powertrain system of an automobile consists of a power source (engine or battery) that transmits power through components such as the transmission, transfer case, final drive, and wheel-end reducers. This process reduces speed and increases torque, transferring power to the wheels to drive the vehicle. The transmission, transfer case, final drive, and wheel-end reducers are composed of gear pairs, which are generally made of 45# steel or medium carbon alloy steel. Steel gears are heavy, accounting for 5% to 10% of the vehicle's curb weight. Automobile gears require inspection or replacement after a certain mileage. Reports indicate that in commercial vehicles, under heavy loads (sometimes overloaded), the final drive gears wear out in as little as six months, requiring replacement of the final drive. Therefore, finding a lightweight, wear-resistant material to manufacture gears is crucial for reducing vehicle weight, improving wear resistance, and increasing mileage.

[0005] This invention utilizes a novel composite material to manufacture lightweight, wear-resistant automotive gears. For the same gear dimensions, this gear, made from a novel carbon short fiber reinforced aluminum matrix composite material, exhibits a lower specific gravity (2.2–2.8 g / cm³). 3 However, the specific gravity of steel is 7.8 g / cm³. 3 One-third of the weight of the composite material is lightweight, reducing the weight of automotive gears by approximately 65%. Furthermore, its mechanical properties achieve higher bending and wear resistance, with a strength increase of about 20%, leading to a longer service life for gear components. It is foreseeable that the application of this new material will significantly reduce the curb weight of automobiles, achieving the goal of lightweighting, energy conservation, emission reduction, and improving automotive technology.

[0006] It is understood that lightweight materials are generally used in automotive body panels and some connecting parts where the stress is relatively small, but have not yet been applied to gear components that require bending resistance, wear resistance, alternating stress, and are subjected to large forces. This invention, "A Lightweight and Wear-Resistant Automotive Gear Manufactured with a Novel Composite Material," belongs to the field of new automotive materials technology, represents the application of a new material, and is an innovative and inventive application technology. III. Summary of the Invention

[0007] The purpose of this invention is twofold: firstly, to reduce the weight of automotive gears, making the car lighter; and secondly, to reduce the frictional resistance and frictional loss between gears, achieving a balance between lightness and wear resistance.

[0008] To achieve this objective, this invention creatively develops a novel carbon (graphite) short fiber reinforced aluminum-based composite material for manufacturing lightweight, wear-resistant automotive gears. The invention's content and mechanism are as follows:

[0009] Modern science has confirmed that high-performance reinforcing materials play a crucial functional role in structural composite materials. Carbon (graphite) short fibers are an effective high-performance reinforcing material; carbon fiber is a special type of fiber composed of carbon. Carbon fiber not only possesses advantages such as light weight, high temperature resistance, wear resistance, corrosion resistance, and ease of processing, but more importantly, it has a microcrystalline structure with a preferred orientation along the fiber axis, exhibiting extremely high tensile strength and elastic modulus along the fiber axis direction. This allows it to enhance the strength, stiffness, and toughness of metal matrix composites. Typically, the tensile strength of carbon fiber can reach 2.1–3.5 GPa, and the Young's modulus can reach 200–800 GPa.

[0010] By using carbon fiber as a reinforcing material (high-performance reinforcing agent) and combining it with aluminum alloys in a certain proportion and manner to form novel composite materials, a material with superior properties that cannot be obtained from a single material can be obtained. Through composite materials, not only can the properties of several materials complement each other, but new characteristics not found in a single material can also be produced.

[0011] This invention is based on the performance characteristics of the aforementioned functional structure of carbon (graphite) short fibers, and creatively uses carbon (graphite) short fiber powder and aluminum alloy powder particles as the main raw materials for lightweight and wear-resistant automotive gears for application research.

[0012] This invention utilizes the microcrystalline structure of carbon (graphite) fibers and their lightweight, wear-resistant, oil-lubricated, and high-stiffness and tensile strength properties as reinforcing materials. The matrix is ​​composed of aluminum alloy, which possesses good fracture toughness, high tensile strength, excellent wear resistance, and low specific gravity. The composition ratio is: carbon (graphite) short fibers ≤40%, aluminum alloy ≥60%. Through wet milling, the carbon fiber powder particles and aluminum alloy powder particles are uniformly mixed, and the aluminum alloy powder particles are refined, with the grains becoming spherical. Under high temperature and hot isostatic pressing, a solid-liquid phase sintering is achieved. The aluminum alloy acts as both the matrix structure and the binder, bonding the carbon fiber particles together. Because carbon (graphite) fiber powder particles and aluminum powder particles are mixed and aggregated together in a disordered and uniform manner, during the sintering process, the powder particle aggregates become crystalline aggregates; the disordered arrangement of carbon fibers forms a fiber network microcrystalline structure. This microcrystalline structure of carbon fibers has a preferred orientation along the fiber axis, and has extremely high bending strength and elastic modulus along the fiber axis direction. Therefore, it can enhance the overall strength, stiffness and toughness of aluminum alloy composite materials.

[0013] This invention creatively uses carbon (graphite) short fiber powder particles and aluminum alloy powder particles as the main raw materials for lightweight and wear-resistant automotive gears. Through special processes such as wet grinding and mixing, drying and sieving, wax-doped granulation, cold isostatic pressing, dewaxing, and hot isostatic pressing at a high temperature of about 700°C for solid-liquid phase sintering, a new lightweight and wear-resistant automotive gear made of carbon fiber reinforced aluminum alloy matrix composite material is prepared. IV. Description of the attached drawings

[0014] Figure 1 Preparation process of lightweight and wear-resistant automotive gears made of a novel composite material V. Detailed Implementation Methods

[0015] The specific embodiments of the present invention, "a lightweight and wear-resistant automotive gear manufactured using a novel composite material," are as follows:

[0016] (Since the equipment used to manufacture lightweight and wear-resistant gears made of carbon fiber reinforced aluminum alloy matrix composites for automobiles varies, the optimal and expected material performance indicators can be achieved by adjusting specific process parameters.)

[0017] 1. Mixing and drying

[0018] Carbon (graphite) short fiber powder and aluminum alloy powder were used as the main materials for lightweight, wear-resistant gears in automobiles, with the following composition ratio: carbon (graphite) short fiber ≤40%, aluminum alloy ≥60%. These two powders were placed in a drum ball mill and wet-milled for approximately 4 to 6 hours using steel balls and a steel-lined inner plate, with alcohol as the wet-milling liquid medium. Then, the mixture was vibrated and dried at approximately 100°C, and the alcohol was recovered. The mixture was sieved through a 100-mesh sieve to obtain a mixture of carbon fiber and aluminum alloy powder particles with an average size of approximately 130 micrometers.

[0019] The main purpose of this process is to mix carbon fiber powder particles and aluminum alloy powder particles evenly, grind the powder particles into uniform size, make the aluminum alloy grains finer, and grind them into round particles.

[0020] Note: The raw and auxiliary materials used in this invention, such as carbon (graphite) short fiber powder particles with the same diameter as metal powder particles, aluminum alloy / aluminum-magnesium alloy powder particles, alcohol, paraffin, etc., are all provided by other manufacturers and are not within the scope of this invention.

[0021] 2. Granulation with wax addition

[0022] The mixture of dried and sieved carbon fiber and aluminum powder particles is placed in a spiral mixer, and about 5% to 8% liquid paraffin is added as a molding agent. After being mixed evenly, it is dried by spray dryer to produce spherical powder particles of 0.2 to 0.5 mm.

[0023] The purpose of adding wax is mainly to give the pressed semi-finished automotive lightweight wear-resistant gear blanks, after the powder and granule mixture is pressed, a certain strength so that they will not collapse during subsequent processes (such as processing or handling of the semi-finished blanks).

[0024] The purpose of granulation is mainly to give the powder mixture a certain degree of fluidity, so that it can fill the mold cavity and be pressed into shape.

[0025] 3. Press molding

[0026] Based on the shape, specifications, and dimensions of the automotive gears, design and manufacture the molds for cold isostatic pressing (including the loosely packed volume of the powder mixture of carbon fiber and aluminum alloy powder, and the relationship between the volume and the sintering shrinkage ratio, etc.).

[0027] A mixture of wax-coated spray-granulated carbon fiber and aluminum alloy powder particles is placed in a molding die and pressed into shape in a cold isobaric press with a capacity of 100 to 500 tons to obtain a lightweight, wear-resistant automotive gear preform. During the pressing process, the powder particles undergo a certain degree of deformation, and the carbon (graphite) short fiber powder particles and aluminum alloy particles are densified and compressed together.

[0028] Note: The molds used for cold isostatic pressing of powder mixtures are usually designed and manufactured by specialized mold designers and process departments. The scope of this invention does not involve the design and manufacture of molds for pressing.

[0029] 4. Dewaxing

[0030] Lightweight wear-resistant automotive gear semi-finished blanks, formed by cold isostatic pressing, are placed in a bell-type dewaxing furnace and kept at a temperature of about 100-200℃ (the temperature before the paraffin melts and flows out but has not yet decomposed) for 4-8 hours to dewax (recover the paraffin). After cooling, the dewaxed gear semi-finished blanks are obtained.

[0031] 5. Sintering

[0032] The dewaxed gear semi-finished blank is placed in a 100-300 ton hot isostatic press and sintered at a high temperature of about 700℃ (where the aluminum alloy matrix and binder are in a solid-liquid phase sintering state at their melting critical temperature) for 2-4 hours. After cooling, lightweight and wear-resistant automotive gear products made of carbon (graphite) short fiber reinforced aluminum matrix composite material are obtained.

[0033] Sintering is a crucial step in the manufacturing process, primarily aimed at controlling the microstructure and properties of the product. During sintering, the previously disordered, uniformly mixed, densely compressed carbon (graphite) powder particles and aluminum powder particles transform from powder aggregates into crystalline aggregates. The disordered arrangement of the carbon fibers forms a fibrous network microcrystalline structure within the gear. This microcrystalline structure exhibits a preferred orientation along the fiber axis, causing the aluminum alloy grains to follow the carbon fiber orientation, resulting in a disordered, fibrous network. Furthermore, the carbon fibers possess extremely high flexural strength and elastic modulus along the fiber axis, thus enhancing the overall strength, stiffness, and toughness of the aluminum alloy composite gear.

[0034] The lightweight, wear-resistant gear products made of carbon fiber reinforced aluminum alloy composite material have a specific gravity of approximately 2.2–2.8 g / cm³. 3 Only steel has a specific gravity of approximately 7.8 g / cm³. 3 It is about one-third the size, with a weight reduction of about 65%, and has extremely high wear resistance and good strength and rigidity.

[0035] 6. Finishing

[0036] The lightweight and wear-resistant automotive gears can be obtained by precision machining (milling or grinding, etc.) of the carbon fiber reinforced aluminum alloy composite material obtained after sintering according to the dimensional parameters of automotive gears.

[0037] Note: The manufacturing process technology conditions and parameters involved in this invention may vary slightly depending on the equipment used, including continuously updated and improved process equipment.

[0038] Note: The manufacturing process technology conditions and parameters involved in this invention may vary slightly depending on the equipment used, including continuously updated and improved process equipment.

Claims

1. The present invention, "a lightweight and wear-resistant automotive gear made of a novel composite material", belongs to the field of new automotive materials technology. Automotive gears are important components of a car's power transmission system. Automotive gears are generally made of 45# steel. Steel gears are relatively heavy, and they require inspection or replacement after a certain mileage. This invention creatively uses carbon (graphite) short fibers and aluminum alloy as raw materials, with the following composition ratio: carbon fiber ≤ 40%, aluminum alloy ≥ 60%. After wet grinding, mixing, drying, sieving, and wax-doping granulation, a powder-particle mixture of carbon short fibers and aluminum alloy is obtained. The mixture is placed in a cold isostatic press of approximately 100-500 tons for pressing and molding. After dewaxing at 100-200℃, it is then placed in a hot isostatic press of approximately 100-300 tons at a high temperature of approximately 700℃, which further densifies the carbon short fibers and aluminum alloy grains, causing them to sinter together in a solid-liquid phase, resulting in a lightweight, wear-resistant automotive gear made of carbon short fiber reinforced aluminum-based composite material. The "lightweight and wear-resistant automotive gear" of this invention has the characteristics of high strength and modulus, good wear resistance, and light weight, which is about 30% of the weight of a 45# steel gear. For the same gear size and parameters, the weight is reduced by about 65%, and it is more wear-resistant than a 45# steel gear.

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