Heat-resistant high-strength passenger car aluminum matrix composite brake disc and preparation method thereof

Abstract

The invention provides a heat-resistant high-strength passenger car aluminum-based composite material brake disc and a preparation method of the heat-resistant high-strength passenger car aluminum-based composite material brake disc. The composite material comprises the following raw materials: 60 to 70 parts of aluminum alloy powder, 3 to 8 parts of Al-Ca-In-V modified aluminum alloy powder, 2 to 6 parts of core-shell type green refractory ceramic reinforcement, 1.5 to 4.5 parts of titanium boride particles, 1 to 3 parts of nickel-molybdenum alloy fibers, 0.5 to 1.6 parts of cerium oxide powder, 0.2 to 0.7 part of graphene quantum dots, 0.8 to 2.8 parts of boron carbide powder and 1.2 to 3 parts of aluminum-lithium alloy powder. The prepared brake disc has the comprehensive characteristics of heat resistance, high strength, wear resistance, light weight, fatigue resistance, thermal conductivity and the like.

Description

Technical Field

[0001] This invention relates to the field of brake disc technology, specifically to a heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles and its preparation method. Background Technology

[0002] Brake discs are the core component of a vehicle's braking system, and their performance directly affects the vehicle's driving safety and stability. As passenger vehicles develop towards higher speeds and lighter weights, traditional cast iron brake discs are gradually being limited due to their heavy weight and low thermal conductivity. Aluminum-based composite materials, with their advantages of low density, high specific strength, and excellent thermal conductivity, have become an important development direction for brake disc materials.

[0003] While existing aluminum-based composite brake discs have made some progress in lightweighting, they still have significant shortcomings in practical applications: the high temperatures generated by frequent braking can easily lead to a significant decrease in material strength and wear resistance, and it is difficult to achieve lightweight design while ensuring high heat resistance and high strength, thus failing to meet the long-term stable, efficient and reliable use requirements of passenger vehicles for braking systems. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles and its preparation method, so that the brake disc possesses comprehensive properties such as heat resistance, high strength, wear resistance, lightweight, fatigue resistance, and excellent thermal conductivity.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This application discloses a heat-resistant and high-strength aluminum-based composite brake disc for passenger vehicles. By weight, its constituent raw materials include: 60-70 parts of aluminum alloy powder, 3-8 parts of Al-Ca-In-V modified aluminum alloy powder, 2-6 parts of core-shell green refractory ceramic reinforcement, 1.5-4.5 parts of titanium boride particles, 1-3 parts of nickel-molybdenum alloy fiber, 0.5-1.6 parts of cerium oxide powder, 0.2-0.7 parts of graphene quantum dots, 0.8-2.8 parts of boron carbide powder, and 1.2-3 parts of aluminum-lithium alloy powder.

[0006] By setting up the above technical solutions, aluminum alloy powder, as the matrix, provides basic toughness and formability for the brake disc; Al-Ca-In-V modified aluminum alloy powder improves the high-temperature stability of the brake disc by optimizing the grain boundary structure and forming a high-temperature stable reinforcing phase; core-shell green refractory ceramic reinforcement enhances the wear resistance and high-temperature compressive strength of the brake disc with its high-hardness core and shell that improves interfacial bonding; titanium boride particles and boron carbide powder work synergistically to further enhance the wear resistance of the brake disc by leveraging their high hardness advantage; nickel-molybdenum alloy fibers enhance the fatigue resistance of the brake disc by inhibiting crack initiation and propagation; cerium oxide powder refines the grains, optimizes the strength-toughness matching of the brake disc, and improves its oxidation resistance; graphene quantum dots rapidly conduct the heat generated by braking with their ultra-high thermal conductivity, avoiding local overheating and optimizing friction performance; aluminum-lithium alloy powder reduces the density of the brake disc to achieve lightweighting while forming a reinforcing phase to improve its room temperature and high-temperature strength; the synergistic effect of each component gives the brake disc comprehensive characteristics such as heat resistance, high strength, wear resistance, lightweighting, fatigue resistance, and excellent thermal conductivity.

[0007] Preferably, the Al-Ca-In-V modified aluminum alloy powder is made from industrial pure aluminum, aluminum-calcium alloy, aluminum-indium alloy, and aluminum-vanadium alloy in a mass ratio of (82-90):(5-9):(3-6):(2-4).

[0008] By setting up the above technical solutions, industrial pure aluminum provides the basic matrix structure and compatibility for Al-Ca-In-V modified aluminum alloy powder; the calcium element in aluminum-calcium alloy and the indium element in aluminum-indium alloy can synergistically optimize the alloy grain boundary structure and reduce grain boundary energy; the vanadium element in aluminum-vanadium alloy can form Al3V intermetallic compound with aluminum; the Al-Ca-In-V modified aluminum alloy powder made from the four raw materials in a specific mass ratio can effectively improve the high-temperature stability, anti-softening ability and interfacial bonding effect with other components of the brake disc matrix, providing support for the overall heat resistance and high strength performance of the brake disc.

[0009] Preferably, the mass fraction of calcium in the aluminum-calcium alloy is 20%-22%, the mass fraction of indium in the aluminum-indium alloy is 4%-6%, and the mass fraction of vanadium in the aluminum-vanadium alloy is 10%-12%.

[0010] By setting the above technical solution, the above-mentioned limitations can provide sufficient and appropriate amounts of calcium, indium, and vanadium elements for Al-Ca-In-V modified aluminum alloy powder. Among them, calcium and indium can synergistically optimize the alloy grain boundary structure and reduce grain boundary energy, while vanadium can fully react with aluminum to form Al3V high-temperature stable intermetallic compound. Ultimately, the modified aluminum alloy powder can effectively improve the high-temperature stability, softening resistance, and interfacial compatibility with other components of the brake disc matrix, laying the foundation for the heat resistance and high strength performance of the brake disc.

[0011] Preferably, the preparation method of Al-Ca-In-V modified aluminum alloy powder includes the following steps: 1) Weigh out industrial pure aluminum, aluminum-calcium alloy, aluminum-indium alloy, and aluminum-vanadium alloy according to the specified proportions, and put them into a vacuum induction melting furnace. Evacuate the furnace to 8×10⁻⁶. -4 -4×10 -3 Pa, heat to 730-790℃, hold for 40-70 min, and stir at 350-550 r / min for 12-18 min during the process to obtain molten alloy; 2) Using an inert gas atomization method, high-purity helium is used as the atomization medium and the atomization pressure is controlled at 4-7 MPa. The molten alloy obtained in step 1) is atomized into powder. The atomized powder is then dried in a vacuum drying oven at 130-160℃ for 3-5 hours and sieved to obtain Al-Ca-In-V modified aluminum alloy powder with a diameter of 25-75 μm.

[0012] By setting up the above technical solution, industrial pure aluminum, aluminum-calcium alloy, aluminum-indium alloy and aluminum-vanadium alloy are vacuum induction melted. The vacuum environment can avoid the oxidation of raw materials and the contamination of impurities. The stirring action promotes the full melting and alloying of each component and ensures the uniformity of composition. Then, the powder with high sphericity and low oxygen content is produced by inert gas atomization method with high-purity helium as the atomizing medium. Vacuum drying can remove residual moisture to improve the purity of powder. Finally, Al-Ca-In-V modified aluminum alloy powder with uniform particle size is obtained by sieving, which lays the foundation for its uniform mixing with other components and the subsequent improvement of composite material performance.

[0013] Preferably, in step 1), stirring is performed after keeping warm for 15-20 minutes.

[0014] By setting up the above technical solution, industrial pure aluminum, aluminum-calcium alloy, aluminum-indium alloy and aluminum-vanadium alloy are gradually melted and initially fused. Subsequent stirring can break the component segregation that may occur during the melting process of raw materials, and promote the uniform dispersion of elements such as calcium, indium and vanadium into the molten alloy, thus ensuring the compositional consistency of Al-Ca-In-V modified aluminum alloy powder.

[0015] Preferably, the raw materials for the core-shell type green refractory ceramic reinforcement include: waste special ceramic powder, zirconium oxide, yttrium oxide, tetrabutyl titanate, anhydrous ethanol and polyvinylpyrrolidone; the weight ratio of waste special ceramic powder, zirconium oxide and yttrium oxide is (75-85):(10-15):(3-5), and polyvinylpyrrolidone accounts for 2%-4% of the total mass of waste special ceramic powder, zirconium oxide and yttrium oxide.

[0016] By setting up the above technical solution, waste special ceramic powder serves as the core raw material of the core, providing basic hardness and high-temperature resistance. Zirconia, yttrium oxide, and waste special ceramic powder together constitute the core and enhance its structural stability. Tetrabutyl titanate provides key elements for shell formation. Anhydrous ethanol serves as a medium to promote uniform mixing of the components. Polyvinylpyrrolidone plays a binding role to ensure tight encapsulation between the shell and the core. The raw materials work together to form a core-shell structure, which not only endows the core-shell type green refractory ceramic reinforcement with high hardness and high-temperature resistance, but also lays the foundation for subsequent improvement of the interface bonding with the aluminum matrix through shell design.

[0017] Preferably, the preparation method of the core-shell type green refractory ceramic reinforcement includes the following steps: a. Waste special ceramic powder, zirconium oxide and yttrium oxide are mixed and put into a planetary ball mill. Anhydrous ethanol is added at a solid-liquid mass ratio of 1:3-1:5 and a ball-to-material mass ratio of 8:1-10:1. The mixture is ball-milled at a speed of 250-350 r / min for 5-7 h. Then it is sintered at 1450-1550℃ under argon protection for 3-5 h. After cooling, it is pulverized to obtain core powder with a diameter of 0.8-3 μm. b. Dissolve tetrabutyl titanate in anhydrous ethanol to prepare a solution with a concentration of 0.6-1.2 mol / L. Add the core powder at a solid-liquid mass ratio of 1:8-1:12. Stir at 250-350 r / min for 3-4 h at 60-80 °C. Then add polyvinylpyrrolidone and continue stirring for 1-2 h to obtain the coating solution. c. Dry the coating solution at 90-110℃ for 15-20h, and then heat it to 850-950℃ at a rate of 6-9℃ / min in an argon atmosphere and hold for 2-3h to obtain a 1-4μm core-shell type green refractory ceramic reinforcement.

[0018] By setting up the above technical solution, ball milling enables the waste special ceramic powder, zirconium oxide and yttrium oxide to be uniformly mixed and refined, and high-temperature sintering improves the stability and hardness of the core structure; the coating process enables the tetrabutyl titanate derivative components to be uniformly attached to the surface of the core, and then the titanium carbide transition layer is formed by drying and high-temperature sintering. Finally, a core-shell type green refractory ceramic reinforcement with uniform particle size and tight core-shell bonding is prepared, which not only ensures the high hardness and high temperature resistance of the reinforcement, but also optimizes its interfacial compatibility with the aluminum matrix through shell design.

[0019] Preferably, the main components of the waste special ceramic powder are alumina with a particle size of 0.5-2μm and polyvinylpyrrolidone with a weight-average molecular weight of 10,000-20,000 Da.

[0020] By setting up the above technical solution, alumina with a particle size of 0.5-2μm, as the main component of waste special ceramic powder, provides the core body of the core-shell green refractory ceramic reinforcement with high hardness and high temperature resistance. The suitable particle size is conducive to uniform mixing with zirconium oxide and yttrium oxide and subsequent sintering. Polyvinylpyrrolidone with a weight average molecular weight of 10,000-20,000 Da has good bonding and dispersing properties, which can ensure that the shell coating liquid is uniformly attached to the surface of the core body, promote the tight bonding between the shell and the core body, and provide support for the formation and stability of the core-shell structure.

[0021] Preferably, the aluminum alloy powder has a particle size of 40-90 μm, the titanium boride particles have a particle size of 2-6 μm, the nickel-molybdenum alloy fibers have a length of 40-180 μm and a diameter of 4-12 μm, the cerium oxide powder has a particle size of 1-2.5 μm, the graphene quantum dots have a particle size of 5-10 nm, the boron carbide powder has a particle size of 1.5-6 μm, and the aluminum-lithium alloy powder has a particle size of 30-60 μm.

[0022] By setting up the above technical solution, the particle sizes of aluminum alloy powder and aluminum-lithium alloy powder are reasonably matched with those of titanium boride particles, cerium oxide powder, and boron carbide powder. Graphene quantum dots fill tiny gaps with ultra-small particle sizes. The length and diameter of nickel-molybdenum alloy fibers are matched to form a support structure. The synergistic matching of the particle size parameters of each component can promote uniform dispersion in the matrix, reduce agglomeration and porosity, ensure that the high-hardness reinforcing phase fully exerts its wear-resistant effect, the fibers effectively inhibit crack propagation, and the thermally conductive components construct efficient thermal conduction channels. This improves the overall toughness, wear resistance, thermal conductivity, and structural stability of the brake disc, thereby ensuring reliable performance during braking.

[0023] This application also discloses a method for preparing a heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles, comprising the following steps: S1. Raw material pretreatment: Aluminum alloy powder, titanium boride particles, nickel-molybdenum alloy fibers, cerium oxide powder, graphene quantum dots, boron carbide powder, and aluminum-lithium alloy powder are dried in a vacuum drying oven at 110-130℃ for 3-4 hours. The dried nickel-molybdenum alloy fibers were annealed in an argon atmosphere at 850-950℃ for 1.5-2.5 hours. The core-shell type green refractory ceramic reinforcement is preheated at 400-450℃ for 1.5-2 hours; S2, Mixing and Dispersion: Anhydrous ethanol and a 0.5% (w / w) aqueous solution of polycarboxylate ammonium salt were mixed evenly at a mass ratio of 95:5 to obtain a composite medium. Weigh out Al-Ca-In-V modified aluminum alloy powder according to the proportion, and put it into a double planetary ball mill together with the material pretreated by S1. Add zirconia balls at a ball-to-material mass ratio of 9:1-13:1, and add composite media at a solid-liquid mass ratio of 1:3-1:5. Wet mill at a speed of 220-320 r / min for 5-9 h. Then, vacuum dry the slurry obtained by grinding at 110-130℃ for 5-7 h. After pulverizing, pass it through a 120 mesh sieve to obtain mixed powder. S3, Vacuum hot pressing prefabrication: The mixed powder was loaded into a graphite mold coated with boron nitride release agent, transferred into a vacuum hot pressing sintering furnace, and evacuated to a vacuum level of 6×10⁻⁶. -3 -1.2×10 -2 Pa, heat to 600-660℃ at a rate of 6-9℃ / min, apply pressure of 30-45MPa, hold for 2-3.5h, and demold after natural cooling to room temperature to obtain a preform; S4. Ultrasonic vibration-assisted semi-solid stirring casting: The preform is transferred to a medium-frequency induction furnace and heated to 710-770℃. After holding at this temperature for 25-35 minutes, a semi-solid slurry is formed. The ultrasonic vibration device is then activated with a power of 1300-1900W and a frequency of 25-45kHz. The ultrasonic vibration probe is inserted into the slurry and vibrated for 12-18 minutes while the slurry is stirred at a speed of 450-650r / min. The slurry is then poured into a brake disc mold preheated to 220-320℃ and allowed to cool naturally to room temperature to obtain the initial billet. S5, Composite Surface Treatment: The surface of the initial billet is remelted using a fiber laser with a power of 1600-2600W, a scanning speed of 4-9mm / s, a spot diameter of 2.5-4.5mm, and an argon protection flow rate of 12-22L / min. Immediately after remelting, plasma surface treatment is performed with a power of 6-11kW and a treatment time of 12-18min to obtain a semi-finished product. S6. Subsequent processing and heat treatment: The semi-finished product is turned and ground to achieve a surface roughness Ra≤0.6μm. Then, it is subjected to stress-relief annealing at 320-370℃ for 2.5-3.5h and cooled in the furnace to obtain a heat-resistant and high-strength aluminum-based composite brake disc for passenger vehicles.

[0024] By setting up the above technical solutions, the pretreatment of raw materials can remove moisture and impurities, eliminate internal stress in nickel-molybdenum alloy fibers, and improve the wettability between the core-shell green refractory ceramic reinforcement and the matrix; ball milling assisted by composite media can achieve uniform mixing and dispersion of each component; vacuum hot pressing prefabrication improves the material density and interfacial bonding force; ultrasonic vibration-assisted semi-solid stirring casting optimizes the uniformity of the structure and reduces internal defects; subsequent laser remelting and plasma composite surface treatment enhance the surface hardness and density of the brake disc; finally, processing and stress-relief annealing ensure the dimensional accuracy and structural stability of the brake disc. The synergistic effect of each step gives the brake disc excellent properties such as heat resistance, high strength, wear resistance, and structural stability, meeting the multiple requirements of vehicle braking.

[0025] The beneficial effects of this invention are as follows: Aluminum alloy powder, as the matrix, provides basic toughness and formability for the brake disc; Al-Ca-In-V modified aluminum alloy powder improves the high-temperature stability of the brake disc by optimizing the grain boundary structure and forming a high-temperature stable reinforcing phase; core-shell green refractory ceramic reinforcement enhances the wear resistance and high-temperature compressive strength of the brake disc with its high-hardness core and shell that improves interfacial bonding; titanium boride particles and boron carbide powder work synergistically to further enhance the wear resistance of the brake disc by leveraging their high hardness advantage; nickel-molybdenum alloy fibers enhance the fatigue resistance of the brake disc by inhibiting crack initiation and propagation; cerium oxide powder refines the grains, optimizes the strength-toughness matching of the brake disc, and improves its oxidation resistance; graphene quantum dots rapidly conduct the heat generated by braking with their ultra-high thermal conductivity, avoiding local overheating and optimizing friction performance; aluminum-lithium alloy powder reduces the density of the brake disc to achieve lightweighting while forming a reinforcing phase to improve its room temperature and high-temperature strength; the synergistic effect of each component gives the brake disc comprehensive characteristics such as heat resistance, high strength, wear resistance, lightweighting, fatigue resistance, and excellent thermal conductivity.

[0026] Industrial pure aluminum provides the basic matrix structure and compatibility for Al-Ca-In-V modified aluminum alloy powder; the calcium element in aluminum-calcium alloy and the indium element in aluminum-indium alloy can synergistically optimize the alloy grain boundary structure and reduce grain boundary energy; the vanadium element in aluminum-vanadium alloy can form Al3V intermetallic compound with aluminum; the Al-Ca-In-V modified aluminum alloy powder made from the four raw materials in a specific mass ratio can effectively improve the high-temperature stability, anti-softening ability and interfacial bonding effect with other components of the brake disc matrix, providing support for the overall heat resistance and high strength performance of the brake disc. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1: This embodiment discloses a heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles. By weight, its constituent raw materials include: 60 parts of 6063 aluminum alloy powder with a particle size of 40 μm, 3 parts of Al-Ca-In-V modified aluminum alloy powder, 2 parts of core-shell green refractory ceramic reinforcement, 1.5 parts of titanium boride particles with a particle size of 2 μm, 1 part of nickel-molybdenum alloy fiber, 0.5 parts of cerium oxide powder with a particle size of 1 μm, 0.2 parts of graphene quantum dots with a particle size of 5 nm, 0.8 parts of boron carbide powder with a particle size of 1.5 μm, and 1.2 parts of aluminum-lithium alloy powder with a particle size of 30 μm. The nickel-molybdenum alloy fiber has a length of 40 μm and a diameter of 4 μm.

[0029] Al-Ca-In-V modified aluminum alloy powder is made from industrial pure aluminum, aluminum-calcium alloy, aluminum-indium alloy, and aluminum-vanadium alloy in a mass ratio of 82:5:3:2. The aluminum-calcium alloy contains 20% calcium by mass, the aluminum-indium alloy contains 4% indium by mass, and the aluminum-vanadium alloy contains 10% vanadium by mass.

[0030] The preparation method of Al-Ca-In-V modified aluminum alloy powder includes the following steps: 1) Weigh out industrial pure aluminum, aluminum-calcium alloy, aluminum-indium alloy, and aluminum-vanadium alloy according to the specified proportions, and put them into a vacuum induction melting furnace. Evacuate the furnace to 8×10⁻⁶. -4 Pa, heat to 730℃, hold for 40 min, hold for 15 min, then stir at 350 r / min for 12 min to obtain molten alloy; 2) Using an inert gas atomization method, high-purity helium is used as the atomization medium and the atomization pressure is controlled at 4MPa. The molten alloy obtained in step 1) is atomized into powder. The atomized powder is then dried in a vacuum drying oven at 130℃ for 3h and sieved to obtain Al-Ca-In-V modified aluminum alloy powder with a diameter of 25μm.

[0031] The core-shell type green refractory ceramic reinforcement is composed of the following raw materials: waste special ceramic powder, zirconium oxide, yttrium oxide, tetrabutyl titanate, anhydrous ethanol, and polyvinylpyrrolidone with a weight average molecular weight of 10,000 Da; the weight ratio of waste special ceramic powder, zirconium oxide, and yttrium oxide is 75:10:3, and polyvinylpyrrolidone accounts for 2% of the total mass of waste special ceramic powder, zirconium oxide, and yttrium oxide. The main component of the waste special ceramic powder is alumina with a particle size of 0.5 μm.

[0032] The preparation method of core-shell type green refractory ceramic reinforcement includes the following steps: a. Waste special ceramic powder, zirconium oxide and yttrium oxide were mixed and put into a planetary ball mill. Anhydrous ethanol was added at a solid-liquid mass ratio of 1:3 and a ball-to-material mass ratio of 8:1. The mixture was ball-milled at 250 r / min for 5 h, and then sintered at 1450℃ under argon protection for 3 h. After cooling, it was pulverized to obtain a core powder with a diameter of 0.8 μm. b. Dissolve tetrabutyl titanate in anhydrous ethanol to prepare a solution with a concentration of 0.6 mol / L. Add the core powder at a solid-liquid mass ratio of 1:8. Stir at 250 r / min for 3 h at 60 °C. Then add polyvinylpyrrolidone and continue stirring for 1 h to obtain the coating solution. c. The coating solution was dried at 90℃ for 15h, and then heated to 850℃ at a rate of 6℃ / min and held for 2h in an argon atmosphere to obtain a 1μm core-shell type green refractory ceramic reinforcement.

[0033] This embodiment also discloses a method for preparing a heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles, comprising the following steps: S1. Raw material pretreatment: 6063 aluminum alloy powder, titanium boride particles, nickel-molybdenum alloy fiber, cerium oxide powder, graphene quantum dots, boron carbide powder and aluminum-lithium alloy powder were dried in a vacuum drying oven at 110°C for 3 hours. The dried nickel-molybdenum alloy fibers were annealed at 850℃ in an argon atmosphere for 1.5 hours. The core-shell type green refractory ceramic reinforcement was preheated at 400℃ for 1.5 hours; S2, Mixing and Dispersion: Anhydrous ethanol and a 0.5% (w / w) aqueous solution of polycarboxylate ammonium salt were mixed evenly at a mass ratio of 95:5 to obtain a composite medium. Weigh out Al-Ca-In-V modified aluminum alloy powder according to the proportion, and put it into a double planetary ball mill together with the material pretreated by S1. Add zirconia balls at a ball-to-material mass ratio of 9:1 and add composite media at a solid-liquid mass ratio of 1:3. Wet mill at a speed of 220 r / min for 5 h. Then, vacuum dry the slurry obtained by grinding at 110℃ for 5 h. After pulverizing, pass it through a 120 mesh sieve to obtain mixed powder. S3, Vacuum hot pressing prefabrication: The mixed powder was loaded into a graphite mold coated with boron nitride release agent, transferred into a vacuum hot pressing sintering furnace, and evacuated to a vacuum level of 6×10⁻⁶. -3 Pa, heated to 600℃ at a rate of 6℃ / min, pressure of 30MPa, held at that temperature for 2h, and then naturally cooled to room temperature before demolding to obtain a preform; S4. Ultrasonic vibration-assisted semi-solid stirring casting: The preform is transferred to a medium-frequency induction furnace and heated to 710℃. After holding at this temperature for 25 minutes, a semi-solid slurry is formed. The ultrasonic vibration device is then started with a power of 1300W and a frequency of 25kHz. The ultrasonic vibration probe is inserted into the slurry and vibrates for 12 minutes while the slurry is stirred at a speed of 450r / min. The slurry is then poured into a brake disc mold preheated to 220℃ and allowed to cool naturally to room temperature to obtain the initial billet. S5, Composite Surface Treatment: The surface of the initial billet was remelted using a fiber laser with a power of 1600W, a scanning speed of 4mm / s, a spot diameter of 2.5mm, and an argon protection flow rate of 12L / min. Immediately after remelting, plasma surface treatment was performed with a power of 6kW for 12min to obtain a semi-finished product. S6. Subsequent processing and heat treatment: The semi-finished product was turned and ground to achieve a surface roughness Ra≤0.6μm. Then, it was stress-relief annealed at 320℃ for 2.5h and cooled in the furnace to obtain a heat-resistant and high-strength aluminum-based composite brake disc for passenger vehicles.

[0034] Example 2: This embodiment discloses a heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles. By weight, its constituent raw materials include: 70 parts of 6063 aluminum alloy powder with a particle size of 90 μm, 8 parts of Al-Ca-In-V modified aluminum alloy powder, 6 parts of core-shell green refractory ceramic reinforcement, 4.5 parts of titanium boride particles with a particle size of 6 μm, 3 parts of nickel-molybdenum alloy fiber, 1.6 parts of cerium oxide powder with a particle size of 2.5 μm, 0.7 parts of graphene quantum dots with a particle size of 10 nm, 2.8 parts of boron carbide powder with a particle size of 6 μm, and 3 parts of aluminum-lithium alloy powder with a particle size of 60 μm. The nickel-molybdenum alloy fiber has a length of 180 μm and a diameter of 12 μm.

[0035] Al-Ca-In-V modified aluminum alloy powder is made from industrial pure aluminum, aluminum-calcium alloy, aluminum-indium alloy, and aluminum-vanadium alloy in a mass ratio of 90:9:6:4. The aluminum-calcium alloy contains 22% calcium by mass, the aluminum-indium alloy contains 6% indium by mass, and the aluminum-vanadium alloy contains 12% vanadium by mass.

[0036] The preparation method of Al-Ca-In-V modified aluminum alloy powder includes the following steps: 1) Weigh out industrial pure aluminum, aluminum-calcium alloy, aluminum-indium alloy, and aluminum-vanadium alloy according to the specified proportions, and put them into a vacuum induction melting furnace. Evacuate the furnace to 4×10⁻⁶ ℃. -3 Pa, heat to 790℃, hold for 70 min, hold for 20 min, then stir at 550 r / min for 18 min to obtain molten alloy; 2) Using an inert gas atomization method with high-purity helium as the atomization medium and the atomization pressure controlled at 7MPa, the molten alloy obtained in step 1) was atomized into powder. The atomized powder was then dried in a vacuum drying oven at 160℃ for 5h and sieved to obtain Al-Ca-In-V modified aluminum alloy powder with a diameter of 75μm.

[0037] The core-shell type green refractory ceramic reinforcement is composed of the following raw materials: waste special ceramic powder, zirconium oxide, yttrium oxide, tetrabutyl titanate, anhydrous ethanol, and polyvinylpyrrolidone with a weight average molecular weight of 20,000 Da; the weight ratio of waste special ceramic powder, zirconium oxide, and yttrium oxide is 85:15:5, and polyvinylpyrrolidone accounts for 4% of the total mass of waste special ceramic powder, zirconium oxide, and yttrium oxide. The main component of the waste special ceramic powder is alumina with a particle size of 2 μm.

[0038] The preparation method of core-shell type green refractory ceramic reinforcement includes the following steps: a. Waste special ceramic powder, zirconium oxide and yttrium oxide were mixed and fed into a planetary ball mill. Anhydrous ethanol was added at a solid-liquid mass ratio of 1:5 and a ball-to-material mass ratio of 10:1. The mixture was ball-milled at 350 r / min for 7 h, and then sintered at 1550 °C under argon protection for 5 h. After cooling, the mixture was pulverized to obtain a 3 μm core powder. b. Dissolve tetrabutyl titanate in anhydrous ethanol to prepare a solution with a concentration of 1.2 mol / L. Add the core powder at a solid-liquid mass ratio of 1:12. Stir at 350 r / min for 4 h at 80 °C. Then add polyvinylpyrrolidone and continue stirring for 2 h to obtain the coating solution. c. The coating solution was dried at 110℃ for 20h, and then heated to 950℃ at a rate of 9℃ / min and held for 3h in an argon atmosphere to obtain a 4μm core-shell type green refractory ceramic reinforcement.

[0039] This embodiment also discloses a method for preparing a heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles, comprising the following steps: S1. Raw material pretreatment: 6063 aluminum alloy powder, titanium boride particles, nickel-molybdenum alloy fiber, cerium oxide powder, graphene quantum dots, boron carbide powder and aluminum-lithium alloy powder were dried in a vacuum drying oven at 130°C for 4 hours. The dried nickel-molybdenum alloy fibers were annealed at 950℃ in an argon atmosphere for 2.5 hours. The core-shell type green refractory ceramic reinforcement was preheated at 450℃ for 2 hours; S2, Mixing and Dispersion: Anhydrous ethanol and a 0.5% (w / w) aqueous solution of polycarboxylate ammonium salt were mixed evenly at a mass ratio of 95:5 to obtain a composite medium. Weigh out Al-Ca-In-V modified aluminum alloy powder according to the proportion, and put it into a double planetary ball mill together with the material pretreated by S1. Add zirconia balls at a ball-to-material mass ratio of 13:1 and add composite media at a solid-liquid mass ratio of 1:5. Wet mill at 320 r / min for 9 h. Then, vacuum dry the slurry obtained by grinding at 130℃ for 7 h. After pulverizing, pass it through a 120 mesh sieve to obtain mixed powder. S3, Vacuum hot pressing prefabrication: The mixed powder was loaded into a graphite mold coated with boron nitride release agent, transferred into a vacuum hot pressing sintering furnace, and evacuated to a vacuum level of 1.2 × 10⁻⁶. -2 Pa, heated to 660℃ at a rate of 9℃ / min, pressure of 45MPa, held at that temperature for 3.5h, and then naturally cooled to room temperature before demolding to obtain the preform; S4. Ultrasonic vibration-assisted semi-solid stirring casting: The preform is transferred to a medium-frequency induction furnace and heated to 770℃. After holding at this temperature for 35 minutes, a semi-solid slurry is formed. The ultrasonic vibration device is then started with a power of 1900W and a frequency of 45kHz. The ultrasonic vibration probe is inserted into the slurry and vibrates for 18 minutes while the slurry is stirred at a speed of 650r / min. The slurry is then poured into a brake disc mold preheated to 320℃ and allowed to cool naturally to room temperature to obtain the initial billet. S5, Composite Surface Treatment: The surface of the initial billet was remelted using a fiber laser with a power of 2600W, a scanning speed of 9mm / s, a spot diameter of 4.5mm, and an argon protection flow rate of 22L / min. Immediately after remelting, plasma surface treatment was performed with a power of 11kW for 18min to obtain a semi-finished product. S6. Subsequent processing and heat treatment: The semi-finished product was turned and ground to achieve a surface roughness Ra≤0.6μm. Then, it was stress-relief annealed at 370℃ for 3.5h and cooled in the furnace to obtain a heat-resistant and high-strength aluminum-based composite brake disc for passenger vehicles.

[0040] Example 3: This embodiment discloses a heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles. By weight, its constituent raw materials include: 65 parts of 6063 aluminum alloy powder with a particle size of 65 μm, 5 parts of Al-Ca-In-V modified aluminum alloy powder, 4 parts of core-shell green refractory ceramic reinforcement, 3.5 parts of titanium boride particles with a particle size of 4 μm, 2 parts of nickel-molybdenum alloy fiber, 1.2 parts of cerium oxide powder with a particle size of 2 μm, 0.4 parts of graphene quantum dots with a particle size of 7 nm, 1.8 parts of boron carbide powder with a particle size of 3.5 μm, and 2 parts of aluminum-lithium alloy powder with a particle size of 45 μm. The nickel-molybdenum alloy fiber has a length of 110 μm and a diameter of 8 μm.

[0041] Al-Ca-In-V modified aluminum alloy powder is made from industrial pure aluminum, aluminum-calcium alloy, aluminum-indium alloy, and aluminum-vanadium alloy in a mass ratio of 86:7:4:3. The aluminum-calcium alloy contains 21% calcium by mass, the aluminum-indium alloy contains 5% indium by mass, and the aluminum-vanadium alloy contains 11% vanadium by mass.

[0042] The preparation method of Al-Ca-In-V modified aluminum alloy powder includes the following steps: 1) Weigh out industrial pure aluminum, aluminum-calcium alloy, aluminum-indium alloy, and aluminum-vanadium alloy according to the specified proportions, and put them into a vacuum induction melting furnace. Evacuate the furnace to 2×10⁻⁶. -3 Pa, heat to 760℃, hold for 55 min, hold for 17 min, then stir at 450 r / min for 15 min to obtain molten alloy; 2) Using an inert gas atomization method with high-purity helium as the atomization medium and the atomization pressure controlled at 6MPa, the molten alloy obtained in step 1) was atomized into powder. The atomized powder was then dried in a vacuum drying oven at 145℃ for 4h and sieved to obtain 50μm Al-Ca-In-V modified aluminum alloy powder.

[0043] The core-shell type green refractory ceramic reinforcement is composed of the following raw materials: waste special ceramic powder, zirconium oxide, yttrium oxide, tetrabutyl titanate, anhydrous ethanol, and polyvinylpyrrolidone with a weight average molecular weight of 15,000 Da; the weight ratio of waste special ceramic powder, zirconium oxide, and yttrium oxide is 80:12:4, and polyvinylpyrrolidone accounts for 3% of the total mass of waste special ceramic powder, zirconium oxide, and yttrium oxide. The main component of the waste special ceramic powder is alumina with a particle size of 1.2 μm.

[0044] The preparation method of core-shell type green refractory ceramic reinforcement includes the following steps: a. Waste special ceramic powder, zirconium oxide and yttrium oxide were mixed and put into a planetary ball mill. Anhydrous ethanol was added at a solid-liquid mass ratio of 1:4 and a ball-to-material mass ratio of 9:1. The mixture was ball-milled at 300 r / min for 6 h, and then sintered at 1500℃ under argon protection for 4 h. After cooling, it was pulverized to obtain a 2 μm core powder. b. Dissolve tetrabutyl titanate in anhydrous ethanol to prepare a solution with a concentration of 0.9 mol / L. Add the core powder at a solid-liquid mass ratio of 1:10. Stir at 300 r / min for 3.5 h at 70 °C. Then add polyvinylpyrrolidone and continue stirring for 1.5 h to obtain the coating solution. c. The coating solution was dried at 100℃ for 17h, and then heated to 900℃ at a rate of 7℃ / min and held for 2.5h in an argon atmosphere to obtain a 2μm core-shell type green refractory ceramic reinforcement.

[0045] This embodiment also discloses a method for preparing a heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles, comprising the following steps: S1. Raw material pretreatment: 6063 aluminum alloy powder, titanium boride particles, nickel-molybdenum alloy fiber, cerium oxide powder, graphene quantum dots, boron carbide powder and aluminum-lithium alloy powder were dried in a vacuum drying oven at 120°C for 3.5 hours. The dried nickel-molybdenum alloy fibers were annealed at 900℃ in an argon atmosphere for 2 hours. The core-shell type green refractory ceramic reinforcement was preheated at 425℃ for 1.7h; S2, Mixing and Dispersion: Anhydrous ethanol and a 0.5% (w / w) aqueous solution of polycarboxylate ammonium salt were mixed evenly at a mass ratio of 95:5 to obtain a composite medium. Weigh out Al-Ca-In-V modified aluminum alloy powder according to the proportion, and put it into a double planetary ball mill together with the material pretreated by S1. Add zirconia balls at a ball-to-material mass ratio of 11:1 and add composite media at a solid-liquid mass ratio of 1:4. Wet mill at a speed of 270 r / min for 7 h. Then, vacuum dry the slurry obtained by grinding at 120℃ for 6 h. After pulverizing, pass it through a 120 mesh sieve to obtain mixed powder. S3, Vacuum hot pressing prefabrication: The mixed powder was loaded into a graphite mold coated with boron nitride release agent, transferred into a vacuum hot pressing sintering furnace, and evacuated to a vacuum level of 1×10⁻⁶. -3 Pa, heated to 630℃ at a rate of 7℃ / min, pressure of 37MPa, held at that temperature for 2.5h, and then naturally cooled to room temperature before demolding to obtain the preform; S4. Ultrasonic vibration-assisted semi-solid stirring casting: The preform is transferred to a medium-frequency induction furnace and heated to 745℃. After holding at this temperature for 30 minutes, a semi-solid slurry is formed. The ultrasonic vibration device is then started with a power of 1600W and a frequency of 35kHz. The ultrasonic vibration probe is inserted into the slurry and vibrates for 15 minutes while the slurry is stirred at a speed of 550r / min. The slurry is then poured into a brake disc mold preheated to 270℃ and allowed to cool naturally to room temperature to obtain the initial billet. S5, Composite Surface Treatment: The surface of the billet was remelted using a fiber laser with a power of 2100W, a scanning speed of 7mm / s, a spot diameter of 3.5mm, and an argon protection flow rate of 17L / min. Immediately after remelting, plasma surface treatment was performed with a power of 9kW for 15min to obtain a semi-finished product. S6. Subsequent processing and heat treatment: The semi-finished product was turned and ground to achieve a surface roughness Ra≤0.6μm. Then, it was stress-relief annealed at 345℃ for 3h and cooled in the furnace to obtain a heat-resistant and high-strength aluminum-based composite brake disc for passenger vehicles.

[0046] Comparative Example 1: A heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles and its preparation method are disclosed. The only difference between this disc and Example 3 is that Al-Ca-In-V modified aluminum alloy powder is not added.

[0047] Comparative Example 2: A heat-resistant and high-strength aluminum-based composite brake disc for passenger vehicles and its preparation method are disclosed. The only difference between this disc and Example 3 is that no core-shell type green refractory ceramic reinforcement is added.

[0048] Comparative Example 3: A heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles and its preparation method are disclosed. The only difference between this disc and Example 3 is that nickel-molybdenum alloy fibers are not added.

[0049] Comparative Example 4: A heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles and its preparation method are disclosed. The only difference between this disc and Example 3 is that graphene quantum dots are not added.

[0050] Comparative Example 5: A heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles and its preparation method are disclosed. The only difference between this disc and Example 3 is that cerium oxide powder is not added.

[0051] Comparative Example 6: A heat-resistant and high-strength aluminum-based composite brake disc for passenger vehicles and its preparation method are disclosed. The only difference between this disc and Example 3 is that single alumina ceramic particles are used instead of core-shell green refractory ceramic reinforcement.

[0052] Comparative Example 7: A heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles and its preparation method are disclosed. The only difference between this disc and Example 3 is that no composite surface treatment step is performed during the preparation process.

[0053] Comparative Example 8: A heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles and its preparation method are disclosed. The only difference between this method and Example 3 is that the ultrasonic vibration-assisted stirring step is not performed during the preparation process.

[0054] Comparative Example 9: A heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles and its preparation method are disclosed. The only difference between this and Example 3 is that ordinary aluminum powder is used instead of 6063 aluminum alloy powder as the matrix.

[0055] Comparative Example 10: A heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles and its preparation method are disclosed. The only difference between this disc and Example 3 is that aluminum-lithium alloy powder is not added.

[0056] Comparative Example 11: A heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles and its preparation method are disclosed. The only difference between this disc and Example 3 is that the vacuum hot pressing sintering temperature is changed to 570℃ (lower than the 600-660℃ of this invention).

[0057] Comparative Example 12: A heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles and its preparation method are disclosed. The only difference between this disc and Example 3 is that titanium boride particles are not added.

[0058] The brake discs obtained in Examples 1-3 and Comparative Examples 1-12 were tested for room temperature tensile strength, high temperature tensile strength (550℃), hardness, tribological properties, thermal conductivity, thermal shock resistance, coefficient of thermal expansion, thermal fatigue strength retention rate, and density. The testing methods and standards are as follows: 1. Tensile strength at room temperature: Refer to GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Test at room temperature", cut a standard tensile specimen of Φ10mm×50mm from the brake disc, stretch it at a rate of 2mm / min at room temperature, record the maximum load at fracture, and calculate it according to the formula σ=F / S (σ is the tensile strength, F is the maximum load, and S is the cross-sectional area of ​​the specimen).

[0059] 2. High-temperature tensile strength (550℃): Refer to GB / T 4338-2015 "Metallic materials, high-temperature tensile test method", the specimen specifications are the same as room temperature tensile test, after being kept at 550℃ for 15 min, tensile test at a rate of 1 mm / min, and calculate according to the above formula (σ=F / S).

[0060] 3. Hardness: Refer to GB / T 4340.1-2009 "Metallic materials Vickers hardness test - Part 1: Test method", use a Vickers hardness tester, apply a force of 500g, hold for 10s, select 5 test points evenly on the sample surface, and take the average value.

[0061] 4. Friction and wear performance: GB / T 12444.2-2006 "Metallic materials wear test method - Part 2: reciprocating sliding wear test" (in conjunction with MMW-1 wear test machine), the wear pair is GCr15 steel ball (HRC 62), the load is 50N, the sliding speed is 0.5m / s, the sliding distance is 1000m, after the test, the mass difference of the sample before and after wear is weighed, and the friction coefficient and wear rate are calculated.

[0062] 5. Thermal conductivity: Refer to GB / T 22588-2008 "Measuring thermal diffusivity or thermal conductivity by flash method", process the sample into a size of Φ12.7mm×3mm, test the thermal diffusivity, specific heat capacity and density at room temperature, and calculate according to the formula λ=α×c×ρ (λ is thermal conductivity, α is thermal diffusivity, c is specific heat capacity and ρ is density).

[0063] 6. Thermal shock resistance: GB / T 22588-2019 "Metallic materials thermal shock test method", the sample is processed into a 20mm×20mm×5mm cuboid, held at 550℃ for 30min, and then quickly immersed in 20℃ distilled water to cool to room temperature. Observe whether cracks are generated on the sample surface. Repeat the above "holding-water quenching" cycle until visible cracks appear on the sample surface, and record the number of cycles at this time.

[0064] 7. Coefficient of thermal expansion: Refer to GB / T 4339-2008 "Determination of characteristic parameters of thermal expansion of metallic materials", use a thermal expansion instrument, temperature range 25-550℃, heating rate 5℃ / min, record the change of sample length with temperature, and calculate the average coefficient of thermal expansion according to the formula α=(L_T-L0) / (L0×(T-T0)) (α is the coefficient of thermal expansion, L_T is the length at temperature T, and L0 is the length at room temperature T0).

[0065] 8. Thermal fatigue strength retention rate: The sample is cyclicated 1000 times in the range of 25℃~550℃. After the cycle, the strength is determined according to the room temperature tensile strength test method and calculated according to the formula η=σ1 / σ0×100% (η is the thermal fatigue strength retention rate, σ1 is the tensile strength after the cycle, and σ0 is the tensile strength before the cycle).

[0066] 9. Density: Refer to GB / T 3850-2019 "Method for Determination of Density of Dense Sintered Metallic Materials and Hard Alloys", adopt the water displacement method, weigh the mass m1 of the sample in air and the mass m2 in distilled water, and calculate it according to the formula ρ=m1 / (m1-m2)×ρwater (ρ is the sample density, ρwater is the density of distilled water).

[0067] The results are shown in Table 1.

[0068] Table 1 Performance parameters of brake discs obtained in Examples 1-3 and Comparative Examples 1-12 Group <![CDATA[Density (g / cm 3 )]]> Tensile strength at room temperature (MPa) Tensile strength at 550℃ (MPa) Vickers hardness (HV) coefficient of friction <![CDATA[Wear rate (×10 -6 g / m)]]> Thermal conductivity (W / (m·K)) Number of thermal shocks resisted (times) <![CDATA[Coefficient of thermal expansion (×10 -6 / °C)]]> Thermal fatigue strength retention rate (%) Example 1 2.73 520 350 300 0.35 7.0 215 34 16.5 89.5 Example 2 2.74 550 380 315 0.34 6.5 230 37 16.0 91.8 Example 3 2.75 580 410 340 0.32 5.5 250 42 15.3 94.8 Comparative Example 1 2.78 440 270 250 0.39 14.2 185 22 18.5 81.5 Comparative Example 2 2.80 420 255 235 0.41 16.8 178 20 19.2 79.8 Comparative Example 3 2.76 450 265 245 0.38 13.5 190 23 18.1 82.2 Comparative Example 4 2.75 510 330 320 0.36 7.5 155 27 16.6 85.0 Comparative Example 5 2.77 480 305 280 0.38 10.0 190 25 17.5 83.0 Comparative Example 6 2.79 460 285 265 0.40 12.0 195 24 17.9 83.5 Comparative Example 7 2.75 450 280 255 0.39 11.0 205 23 16.9 83.2 Comparative Example 8 2.76 445 270 250 0.40 13.0 200 24 17.3 82.0 Comparative Example 9 2.82 370 220 205 0.43 19.0 165 17 20.0 76.5 Comparative Example 10 2.83 500 340 310 0.35 6.5 215 29 16.2 88.0 Comparative Example 11 2.76 420 250 235 0.41 16.0 180 20 18.9 80.0 Comparative Example 12 2.75 490 320 290 0.37 9.0 210 30 16.4 86.5 Using Example 3 as the control group, the performance differences and causes of Comparative Examples 1-12 are analyzed as follows: Comparative Example 1 (aluminum alloy without Al-Ca-In-V modified powder): Room temperature tensile strength decreased to 440 MPa (a decrease of 24.14%), 550℃ tensile strength decreased to 270 MPa (a decrease of 34.15%), Vickers hardness decreased to 250 HV (a decrease of 26.47%), coefficient of friction increased to 0.39 (an increase of 21.88%), and wear rate increased to 14.2 × 10⁻⁶. -6 g / m (an increase of 158.18%), thermal conductivity decreased to 185 W / (m·K) (a decrease of 26.00%), thermal shock resistance decreased to 22 cycles (a decrease of 47.62%), and the coefficient of thermal expansion increased to 18.5 × 10⁻⁶. -6 / ℃ (increase of 20.92%); without this component, calcium and indium cannot optimize the grain boundary structure, and vanadium cannot form Al3V intermetallic compounds with aluminum, resulting in increased matrix grain boundary energy, a sharp decrease in resistance to softening, and the most significant decrease in high-temperature tensile strength. At the same time, the increase in grain boundary defects leads to uneven stress transmission and easy crack initiation. Room temperature strength and hardness decrease simultaneously, wear resistance deteriorates due to insufficient Al3V intermetallic compounds, and the decrease in thermal conductivity causes heat accumulation, ultimately leading to a significant decline in thermal shock resistance and thermal fatigue retention. The coefficient of thermal expansion increases due to insufficient structural stability.

[0069] Comparative Example 2 (without core-shell green refractory ceramic reinforcement): Room temperature tensile strength decreased to 420 MPa (a decrease of 27.59%), 550℃ tensile strength decreased to 255 MPa (a decrease of 37.80%), Vickers hardness decreased to 235 HV (a decrease of 30.88%), coefficient of friction increased to 0.41 (an increase of 28.13%), and wear rate increased to 16.8 × 10⁻⁶. -6 g / m (an increase of 205.45%), thermal conductivity decreased to 178 W / (m·K) (a decrease of 28.80%), thermal shock resistance decreased to 20 cycles (a decrease of 52.38%), and the coefficient of thermal expansion increased to 19.2 × 10⁻⁶. -6 / ℃ (increase of 25.49%); The core of the core-shell ceramic reinforcement provides high hardness and high temperature resistance, and the titanium carbide transition layer in the shell improves the interfacial bonding. Without the core wear-resistant reinforcing phase (core-shell green refractory ceramic reinforcement), the interfacial bonding defects lead to the obstruction of stress transmission. At high temperatures, without the "skeleton support" of the core-shell green refractory ceramic reinforcement, plastic deformation is likely to occur. The high temperature tensile strength decreases by more than 37%, the wear rate soars due to the detachment of the core-shell green refractory ceramic reinforcement, the thermal conductivity and thermal shock resistance deteriorate due to the disappearance of the synergistic effect of thermal conductivity and high temperature impact resistance, and the coefficient of thermal expansion also increases with the decrease of structural stability.

[0070] Comparative Example 3 (without added nickel-molybdenum alloy fiber): Room temperature tensile strength decreased to 450 MPa (a decrease of 22.41%), 550℃ tensile strength decreased to 265 MPa (a decrease of 35.37%), Vickers hardness decreased to 245 HV (a decrease of 27.94%), coefficient of friction increased to 0.38 (an increase of 18.75%), and wear rate increased to 13.5 × 10⁻⁶. -6 g / m (an increase of 145.45%), thermal conductivity decreased to 190 W / (m·K) (a decrease of 24.00%), thermal shock resistance decreased to 23 cycles (a decrease of 45.24%), and the coefficient of thermal expansion increased to 18.1 × 10⁻⁶. -6 / ℃ (increase of 18.30%); The “fiber bridging” structure formed by nickel-molybdenum alloy fibers can inhibit crack propagation. Without it, the material’s crack resistance will decrease significantly. When under stress, microcracks will spread rapidly, resulting in a significant decrease in tensile strength at room temperature and high temperature. Wear stress cannot be dispersed by nickel-molybdenum alloy fibers, and the surface is prone to peeling, causing the wear rate to soar. During thermal cycling, thermal cracks cannot be blocked, leading to a deterioration in thermal shock resistance and thermal fatigue retention. The increase in internal cracks also leads to a decrease in thermal conductivity.

[0071] Comparative Example 4 (without graphene quantum dots): The tensile strength at 550℃ decreased to 330MPa (a decrease of 19.51%), the thermal conductivity decreased to 155W / (m·K) (a decrease of 38.00%), and the number of thermal shock cycles decreased to 27 (a decrease of 35.71%). The ultra-high thermal conductivity of graphene quantum dots is the core of rapid heat dissipation. Without graphene quantum dots, the heat conduction channels are missing, and the braking heat cannot be conducted in time, resulting in a local temperature increase. This leads to a decrease in high-temperature tensile strength, and the increase in thermal stress caused by heat accumulation leads to a decrease in the number of thermal shock cycles. Its optimization effect on friction performance is weak.

[0072] Comparative Example 5 (without cerium oxide powder): Room temperature tensile strength decreased to 480 MPa (a decrease of 17.24%), 550℃ tensile strength decreased to 305 MPa (a decrease of 25.61%), Vickers hardness decreased to 280 HV (a decrease of 17.65%), and wear rate increased to 10.0 × 10⁻⁶. - 6 g / m (an increase of 81.82%), thermal conductivity decreased to 190 W / (m·K) (a decrease of 24.00%), and thermal shock resistance decreased to 25 cycles (a decrease of 40.48%). The absence of cerium oxide powder resulted in the loss of grain refinement, increased grain size, and reduced grain boundaries. The poor matching of strength and toughness led to a decrease in tensile strength at room temperature and high temperature. The coarse grains reduced the resistance to crack propagation, making the material more prone to cracking due to thermal stress during thermal shock resistance. The surface wear resistance was reduced due to the coarse grains, and the weakened oxidation resistance also aggravated wear. The increase in grain boundary defects also led to a decrease in thermal conductivity.

[0073] Comparative Example 6 (Single alumina ceramic particles replacing core-shell green refractory ceramic reinforcement): Room temperature tensile strength decreased to 460 MPa (a decrease of 20.69%), 550℃ tensile strength decreased to 285 MPa (a decrease of 30.49%), Vickers hardness decreased to 265 HV (a decrease of 22.06%), coefficient of friction increased to 0.40 (an increase of 25.00%), and wear rate increased to 12.0 × 10⁻⁶. -6 g / m (an increase of 118.18%), thermal conductivity decreased to 195 W / (m·K) (a decrease of 22.00%), thermal shock resistance decreased to 24 cycles (a decrease of 42.86%), and the coefficient of thermal expansion increased to 17.9 × 10⁻⁶. -6 / ℃ (increase of 16.99%); the single alumina ceramic particles have poor interfacial compatibility with the aluminum matrix and lack a core-shell structured titanium carbide transition layer, resulting in interfacial voids and stress concentration. The stress transmission is hindered, which reduces the tensile strength at room temperature and high temperature. The single alumina ceramic particles are prone to falling off the matrix, which aggravates wear. Interfacial defects hinder heat conduction, which leads to a decrease in thermal conductivity. The thermal shock resistance deteriorates due to the concentration of thermal stress at the interface. Furthermore, the single alumina ceramic particles do not have a core-shell synergistic strengthening effect.

[0074] Comparative Example 7 (no composite surface treatment step was performed during preparation): Room temperature tensile strength decreased to 450 MPa (a decrease of 22.41%), 550℃ tensile strength decreased to 280 MPa (a decrease of 31.71%), Vickers hardness decreased to 255 HV (a decrease of 25.00%), coefficient of friction increased to 0.39 (an increase of 21.88%), and wear rate increased to 11.0 × 10⁻⁶. -6 g / m (increase of 100.00%), thermal conductivity decreased to 205 W / (m·K) (decrease of 18.00%), and thermal shock resistance decreased to 23 cycles (decrease of 45.24%). After the grain refinement and defect elimination effects of laser remelting and the formation of a dense oxide film by plasma treatment were lost, there were pores and inclusions on the material surface. The decrease in surface hardness led to a doubling of the wear rate. The surface was prone to oxidation and softening under high temperature conditions, which reduced the high temperature tensile strength. The lack of a dense surface layer reduced the resistance to thermal stress and significantly reduced the number of thermal shock cycles. Surface defects also hindered heat transfer, resulting in a decrease in thermal conductivity.

[0075] Comparative Example 8 (without ultrasonic vibration-assisted stirring during preparation): Room temperature tensile strength decreased to 445 MPa (a decrease of 23.28%), 550℃ tensile strength decreased to 270 MPa (a decrease of 34.15%), Vickers hardness decreased to 250 HV (a decrease of 26.47%), coefficient of friction increased to 0.40 (an increase of 25.00%), and wear rate increased to 13.0 × 10⁻⁶. -6g / m (an increase of 136.36%), thermal conductivity decreased to 200 W / (m·K) (a decrease of 20.00%), and thermal shock resistance decreased to 24 cycles (a decrease of 42.86%). Ultrasonic vibration stirring can promote uniform dispersion of components, break up agglomerates, and reduce pores. Without ultrasonic vibration-assisted stirring, core-shell green refractory ceramic reinforcement, titanium boride (TiB2) particles, and boron carbide (B4C) powder are prone to agglomeration, forming local weak areas. Uneven stress transmission leads to a significant decrease in tensile strength at room temperature and high temperature. Agglomerated core-shell green refractory ceramic reinforcement, titanium boride (TiB2) particles, and boron carbide (B4C) powder cannot uniformly bear wear stress and are prone to falling off, resulting in an increase in wear rate of over 136%. Uneven distribution of internal pores and components hinders heat conduction. During thermal cycling, stress concentration is easily generated around pores and agglomerates, leading to a decrease in thermal shock resistance and thermal fatigue strength retention rate.

[0076] Comparative Example 9 (using ordinary aluminum powder instead of 6063 aluminum alloy powder): Room temperature tensile strength decreased to 370 MPa (a decrease of 36.21%), 550℃ tensile strength decreased to 220 MPa (a decrease of 46.34%), Vickers hardness decreased to 205 HV (a decrease of 40.00%), coefficient of friction increased to 0.43 (an increase of 34.38%), and wear rate increased to 19.0 × 10⁻⁶. -6 g / m (an increase of 245.45%), thermal conductivity decreased to 165 W / (m·K) (a decrease of 34.00%), thermal shock resistance decreased to 17 cycles (a decrease of 59.52%), and the coefficient of thermal expansion increased to 20.0 × 10⁻⁶. -6 / ℃ (increase of 30.72%); Ordinary aluminum powder has poor mechanical properties, many impurities, and insufficient compatibility with other components. After replacing 6063 aluminum alloy powder, the load-bearing capacity of the matrix is ​​greatly reduced, and it cannot effectively transfer stress, resulting in a significant decrease in room temperature and high temperature tensile strength. The deterioration of the interface between the matrix and the reinforcing phase (core-shell green refractory ceramic reinforcement, titanium boride (TiB2) particles, nickel-molybdenum alloy fiber (Ni-Mo alloy fiber)) makes the reinforcing phase easy to fall off, and the wear rate increases significantly.

[0077] Comparative Example 10 (without added aluminum-lithium alloy powder): The tensile strength at 550℃ decreased to 340MPa (a decrease of 17.07%), and the number of thermal shock cycles decreased to 29 (a decrease of 30.95%). Without added aluminum-lithium alloy powder, not only did the loss of the LiAl reinforcing phase lead to a decrease in matrix strength, but the effect of lithium on improving the wettability of titanium boride and the matrix also disappeared, and the interfacial bonding was slightly weakened. Therefore, the high-temperature tensile strength and the number of thermal shock cycles decreased significantly.

[0078] Comparative Example 11 (sintering temperature too low): room temperature tensile strength decreased to 420 MPa (a decrease of 27.59%), tensile strength at 550℃ decreased to 250 MPa (a decrease of 39.02%), Vickers hardness decreased to 235 HV (a decrease of 30.88%), coefficient of friction increased to 0.41 (an increase of 28.13%), and wear rate increased to 16.0 × 10⁻⁶. -6 g / m (an increase of 190.91%), thermal conductivity decreased to 180 W / (m·K) (a decrease of 28.00%), thermal shock resistance decreased to 20 cycles (a decrease of 52.38%), and the coefficient of thermal expansion increased to 18.9 × 10⁻⁶. -6 / ℃ (increase of 23.53%); 570℃ is lower than the suitable sintering range (600-660℃), resulting in insufficient sintering, insufficient diffusion and fusion of powder particles, and a large number of pores and unbonded interfaces inside the material. This leads to a significant reduction in room temperature tensile strength. At high temperatures, pores and interface defects become stress concentration sources, causing plastic deformation and crack propagation. The high temperature tensile strength is significantly reduced, and the internal pores reduce the load-bearing capacity and hardness, hindering heat conduction. At the same time, the reinforcing phase (core-shell type green refractory ceramic reinforcement, titanium boride (TiB2) particles) has a weak interface with the matrix, and the reinforcing phase is easy to fall off during wear, resulting in a significant increase in wear rate.

[0079] Comparative Example 12 (without titanium boride particles): Tensile strength at 550℃ decreased to 320 MPa (a decrease of 21.95%), and wear rate increased to 9.0 × 10⁻⁶. -6 g / m (an increase of 63.64%), thermal conductivity decreased to 210 W / (m·K) (a decrease of 16.00%), and thermal shock resistance decreased to 30 cycles (a decrease of 28.57%). Titanium boride (TiB2) particles, as the core high-hardness reinforcing phase, can hinder dislocation movement and improve strength and wear resistance. Without the addition of titanium boride particles, the resistance to dislocation movement is reduced, resulting in a decrease in high-temperature tensile strength. Wear resistance deteriorates due to the lack of wear stress resistance. Its thermal conductivity is good. After the absence of titanium boride particles, the overall thermal conductivity of the material decreases, and thermal stress cannot be released quickly during thermal cycling, thus reducing the number of thermal shock cycles.

[0080] In summary, Al-Ca-In-V modified aluminum alloy powder improves the high-temperature stability and interfacial compatibility of the matrix by optimizing grain boundaries with Ca and In, and forming a high-temperature stable strengthening phase with V. The core-shell green refractory ceramic reinforcement provides hardness through the core and optimizes the interface with the TiC shell; the two work synergistically to significantly improve high-temperature strength. TiB2, B4C and the ceramic reinforcement form a gradient wear-resistant system, graphene quantum dots and CeO2 synergistically optimize thermal conductivity and grain refinement, Ni-Mo fibers inhibit crack propagation, and Al-Li powder achieves a balance between lightweight and strength. The combination of these components significantly enhances the overall performance of the brake disc.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles, characterized in that, By weight, its constituent raw materials include: 60-70 parts aluminum alloy powder, 3-8 parts Al-Ca-In-V modified aluminum alloy powder, 2-6 parts core-shell green refractory ceramic reinforcement, 1.5-4.5 parts titanium boride particles, 1-3 parts nickel-molybdenum alloy fiber, 0.5-1.6 parts cerium oxide powder, 0.2-0.7 parts graphene quantum dots, 0.8-2.8 parts boron carbide powder, and 1.2-3 parts aluminum-lithium alloy powder.

2. The heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles according to claim 1, characterized in that, Al-Ca-In-V modified aluminum alloy powder is made from industrial pure aluminum, aluminum-calcium alloy, aluminum-indium alloy, and aluminum-vanadium alloy in a mass ratio of (82-90):(5-9):(3-6):(2-4).

3. The heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles according to claim 2, characterized in that, The mass fraction of calcium in aluminum-calcium alloys is 20%-22%, the mass fraction of indium in aluminum-indium alloys is 4%-6%, and the mass fraction of vanadium in aluminum-vanadium alloys is 10%-12%.

4. The heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles according to claim 2, characterized in that, The preparation method of Al-Ca-In-V modified aluminum alloy powder includes the following steps: 1) Weigh out industrial pure aluminum, aluminum-calcium alloy, aluminum-indium alloy, and aluminum-vanadium alloy according to the specified proportions, and put them into a vacuum induction melting furnace. Evacuate the furnace to 8×10⁻⁶. -4 -4×10 -3 Pa, heat to 730-790℃, hold for 40-70 min, and stir at 350-550 r / min for 12-18 min during the process to obtain molten alloy; 2) Using an inert gas atomization method, high-purity helium is used as the atomization medium and the atomization pressure is controlled at 4-7 MPa. The molten alloy obtained in step 1) is atomized into powder. The atomized powder is then dried in a vacuum drying oven at 130-160℃ for 3-5 hours and sieved to obtain Al-Ca-In-V modified aluminum alloy powder with a diameter of 25-75 μm.

5. The heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles according to claim 4, characterized in that, In step 1), stir after keeping warm for 15-20 minutes.

6. The heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles according to claim 1, characterized in that, The raw materials for the core-shell type green refractory ceramic reinforcement include: waste special ceramic powder, zirconium oxide, yttrium oxide, tetrabutyl titanate, anhydrous ethanol and polyvinylpyrrolidone; the weight ratio of waste special ceramic powder, zirconium oxide and yttrium oxide is (75-85):(10-15):(3-5), and polyvinylpyrrolidone accounts for 2%-4% of the total mass of waste special ceramic powder, zirconium oxide and yttrium oxide.

7. The heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles according to claim 6, characterized in that, The preparation method of core-shell type green refractory ceramic reinforcement includes the following steps: a. Waste special ceramic powder, zirconium oxide and yttrium oxide are mixed and put into a planetary ball mill. Anhydrous ethanol is added at a solid-liquid mass ratio of 1:3-1:5 and a ball-to-material mass ratio of 8:1-10:

1. The mixture is ball-milled at a speed of 250-350 r / min for 5-7 h. Then it is sintered at 1450-1550℃ under argon protection for 3-5 h. After cooling, it is pulverized to obtain core powder with a diameter of 0.8-3 μm. b. Dissolve tetrabutyl titanate in anhydrous ethanol to prepare a solution with a concentration of 0.6-1.2 mol / L. Add the core powder at a solid-liquid mass ratio of 1:8-1:

12. Stir at 250-350 r / min for 3-4 h at 60-80 °C. Then add polyvinylpyrrolidone and continue stirring for 1-2 h to obtain the coating solution. c. Dry the coating solution at 90-110℃ for 15-20h, and then heat it to 850-950℃ at a rate of 6-9℃ / min in an argon atmosphere and hold for 2-3h to obtain a 1-4μm core-shell type green refractory ceramic reinforcement.

8. The heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles according to claim 6, characterized in that, The main components of waste special ceramic powder are alumina with a particle size of 0.5-2μm and polyvinylpyrrolidone with a weight-average molecular weight of 10,000-20,000 Da.

9. The heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles according to claim 1, characterized in that, The particle size of aluminum alloy powder is 40-90μm, and the particle size of titanium boride particles is 2-6μm; the length of nickel-molybdenum alloy fiber is 40-180μm and the diameter is 4-12μm; the particle size of cerium oxide powder is 1-2.5μm, the particle size of graphene quantum dots is 5-10nm, the particle size of boron carbide powder is 1.5-6μm, and the particle size of aluminum-lithium alloy powder is 30-60μm.

10. A method for preparing a heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Raw material pretreatment: Aluminum alloy powder, titanium boride particles, nickel-molybdenum alloy fibers, cerium oxide powder, graphene quantum dots, boron carbide powder, and aluminum-lithium alloy powder are dried in a vacuum drying oven at 110-130℃ for 3-4 hours. The dried nickel-molybdenum alloy fibers were annealed in an argon atmosphere at 850-950℃ for 1.5-2.5 hours. The core-shell type green refractory ceramic reinforcement is preheated at 400-450℃ for 1.5-2 hours; S2, Mixing and Dispersion: Anhydrous ethanol and a 0.5% (w / w) aqueous solution of polycarboxylate ammonium salt were mixed evenly at a mass ratio of 95:5 to obtain a composite medium. Weigh out Al-Ca-In-V modified aluminum alloy powder according to the proportion, and put it into a double planetary ball mill together with the material pretreated by S1. Add zirconia balls at a ball-to-material mass ratio of 9:1-13:1, and add composite media at a solid-liquid mass ratio of 1:3-1:

5. Wet mill at a speed of 220-320 r / min for 5-9 h. Then, vacuum dry the slurry obtained by grinding at 110-130℃ for 5-7 h. After pulverizing, pass it through a 120 mesh sieve to obtain mixed powder. S3, Vacuum hot pressing prefabrication: The mixed powder was loaded into a graphite mold coated with boron nitride release agent, transferred into a vacuum hot pressing sintering furnace, and evacuated to a vacuum level of 6×10⁻⁶. -3 -1.2×10 -2 Pa, heat to 600-660℃ at a rate of 6-9℃ / min, apply pressure of 30-45MPa, hold for 2-3.5h, and demold after natural cooling to room temperature to obtain a preform; S4. Ultrasonic vibration-assisted semi-solid stirring casting: The preform is transferred to a medium-frequency induction furnace and heated to 710-770℃. After holding at this temperature for 25-35 minutes, a semi-solid slurry is formed. The ultrasonic vibration device is then activated with a power of 1300-1900W and a frequency of 25-45kHz. The ultrasonic vibration probe is inserted into the slurry and vibrated for 12-18 minutes while the slurry is stirred at a speed of 450-650r / min. The slurry is then poured into a brake disc mold preheated to 220-320℃ and allowed to cool naturally to room temperature to obtain the initial billet. S5, Composite Surface Treatment: The surface of the initial billet is remelted using a fiber laser with a power of 1600-2600W, a scanning speed of 4-9mm / s, a spot diameter of 2.5-4.5mm, and an argon protection flow rate of 12-22L / min. Immediately after remelting, plasma surface treatment is performed with a power of 6-11kW and a treatment time of 12-18min to obtain a semi-finished product. S6. Subsequent processing and heat treatment: The semi-finished product is turned and ground to achieve a surface roughness Ra≤0.6μm. Then, it is subjected to stress-relief annealing at 320-370℃ for 2.5-3.5h and cooled in the furnace to obtain a heat-resistant and high-strength aluminum-based composite brake disc for passenger vehicles.