A method for preparing a high-performance brake disc of carbon fiber reinforced aluminum matrix composite

Abstract

The application discloses a preparation method of a carbon fiber reinforced aluminum matrix composite high-performance brake disc and relates to the field of composite materials. An aluminum-silicon-copper alloy is used as a matrix, and nano carbon fibers are introduced; the carbon fibers are subjected to interface pretreatment to enhance the combination with the matrix. The brake disc is prepared through processes such as powder mixing, pre-body pressing, melt immersion stirring, casting forming, heat treatment and processing. The prepared brake disc has excellent performances such as high hardness, good wear resistance, stable friction coefficient, high thermal conductivity, long fatigue life and light weight, and is particularly suitable for brake system applications under high-speed or high-load conditions.

Description

Technical Field

[0001] This invention relates to the field of composite materials, and in particular to a method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material. Background Technology

[0002] Brake discs are key friction components in a vehicle's braking system, and their performance directly affects the vehicle's braking efficiency, safety, durability, overall vehicle weight, and fuel / energy consumption. Currently, the mainstream materials for brake discs, existing technological approaches, and their limitations are as follows.

[0003] Traditional automobiles, commercial vehicles, and most passenger cars use cast iron (gray cast iron, ductile iron, graphite cast iron, etc.) or cast steel to manufacture brake discs. These materials are relatively inexpensive, have mature forming processes, and standardized processing techniques. Their advantages include high heat resistance, good resistance to thermal fatigue, and stable friction performance. However, they also have significant disadvantages: they are heavy, especially during high-speed braking or frequent braking, resulting in severe heat accumulation and noticeable brake fade; their heat dissipation performance is not good enough; and their heavy weight is detrimental to vehicle lightweighting, affecting fuel economy or the range of electric vehicles.

[0004] To reduce weight and improve heat dissipation, some technical approaches use aluminum alloys (such as aluminum-silicon, aluminum-silicon-copper, etc.) or other lightweight alloys to manufacture brake discs. Aluminum alloys have much better thermal conductivity than cast iron and lower density, thus reducing weight. For example, patent CN103628005B proposes using an aluminum-silicon-copper alloy matrix with micro / nano carbon fibers as reinforcement, and preparing brake disc materials through melt synthesis and die casting. This patent explicitly states that compared to cast iron brake discs, aluminum-based composites offer significant advantages in terms of faster heat dissipation ("more than four times faster than cast iron") and a 50-60% weight reduction, while also improving fatigue resistance and wear resistance.

[0005] To further improve wear resistance and strength, existing technologies incorporate reinforcing phases, such as ceramic particles (SiC, Al2O3, B4C, etc.), into the aluminum matrix. This allows for the creation of composite brake discs in which the friction layer or the entire brake disc contains these particulate reinforcing materials.

[0006] Patent CN106812837B discloses an aluminum-based composite brake disc and its manufacturing method. The brake disc consists of an aluminum alloy core and a surface friction layer (made of particle-reinforced aluminum-based composite material). The reinforcing particles in the friction layer can be SiC, Al2O3, B4C, or AlN alloys, and the patent provides process parameters such as a particle size range of 3-30µm and a particle content of approximately 10-35%. The manufacturing process includes steps such as casting an aluminum alloy core, adding reinforcing particles to the melt, stirring, casting / pouring, and heat treatment. Other forms include double-layer aluminum-based composite brake discs and surface reinforcement layers with different material structures than the core, aiming to balance lightweight, rigidity, wear resistance, and braking surface performance.

[0007] For applications requiring extreme high-temperature resistance and extremely high wear resistance (such as aircraft, racing cars, and high-speed trains), carbon / carbon-SiC and carbon-ceramic composite brake discs are used. These discs possess extremely high temperature resistance, excellent thermal stability, and lightweight properties. For example, patent CN116238085B discloses a hybrid brake disc made of carbon fiber + SiC + thermoplastic resin, which can withstand temperatures up to approximately 1000°C and has a lifespan approximately 60 times that of a standard cast iron disc.

[0008] Based on the existing technologies and problems mentioned above, the following aspects urgently need improvement / innovation:

[0009] Carbon fiber has been used as a reinforcing agent in aluminum-based brake discs, but there is limited information on carbon fiber-reinforced aluminum materials in existing patents, especially regarding interface treatment, wear, and high-temperature friction stability.

[0010] To enhance the high-temperature stability of the phase, more precise control is needed over oxidation, fracture, and interfacial reactions, such as through pretreatment, coating, and melt environment control.

[0011] Challenges exist in the dispersion and morphology control of the fiber / reinforcing phase, which directly affects the overall mechanical properties and friction surface consistency of the composite material.

[0012] In terms of process integration, it is necessary to ensure lightweight, good heat dissipation, wear and fatigue resistance, controllable manufacturing costs, good processability, and high repeatability in industrial production. Summary of the Invention

[0013] Based on the problems raised in the background art, the present invention proposes a method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material.

[0014] A method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material includes the following steps, in parts by weight:

[0015] (1) Preparation of aluminum-based alloy powder:

[0016] Aluminum (Al): 88.0-95.0 parts

[0017] Silicon (Si): 9.0-13.0 parts

[0018] Copper (Cu): 2.0-5.0 parts

[0019] Magnesium (Mg): 0.1-0.8 parts

[0020] Zinc (Zn): 0.2-1.0 parts

[0021] Iron (Fe): 0.2-1.0 parts

[0022] Manganese (Mn): 0.2-0.5 parts

[0023] Nickel (Ni): ≤0.5 parts

[0024] Titanium (Ti): 0.05-0.5 parts

[0025] Tin (Sn): ≤0.3 parts;

[0026] (2) Carbon fiber pretreatment:

[0027] 0.5-5.0 parts of carbon fiber were heated to 400-600°C and held for 30-60 minutes in a nitrogen atmosphere, then cooled; followed by chemical sensitization treatment.

[0028] (3) Mixing and preforming

[0029] Pretreated carbon fibers and aluminum-based alloy powder are ball-milled at a mass ratio for 30-120 minutes.

[0030] The mixture is pressed into a preform block under a pressure of 50-200 MPa in a nitrogen atmosphere. The size can be predetermined according to the size of the brake disc. The pressing is held at a temperature to make the powder bind together but not melt, and the temperature is held for 0.5-2 hours to obtain the preform.

[0031] (4) Melt immersion and casting

[0032] The melting temperature of the aluminum matrix alloy is controlled at 650-720°C; the melting should be carried out in a nitrogen atmosphere or vacuum to reduce oxidation, and the temperature should be held for 0.5-2 hours to obtain the melt.

[0033] Slowly add the preform to the melt and mechanically stir to disperse the fibers evenly at a speed of 200-1500 rpm for 3-10 minutes. Preheat the mold to 400-600°C and maintain this temperature during casting.

[0034] (5) Heat treatment

[0035] Solution treatment: 480-550°C, hold for 2-6 hours;

[0036] Aging treatment: Temperature 150-250°C, heat preservation for 6-12 hours;

[0037] (6) Machining and friction surface treatment

[0038] Machining to the final geometric dimensions, including turning, milling, and drilling; the surface roughness Ra of the friction surface is controlled within 1.0-3.0µm.

[0039] Preferably, the carbon fiber has a diameter of 0.05-5.0µm and a fiber length of 10-100µm.

[0040] Preferably, the chemical sensitization treatment step is as follows:

[0041] S1: According to the weight range, add 20-40 parts by weight of SnCl2, 0.3-1.4 parts by weight of S-2-hydroxyglutaric acid and 200-300 parts by weight of deionized water into the reaction vessel, stir evenly, immerse 10-20 parts by weight of carbon fiber into the mixed solution, soak at 28-35℃ for 12-22 minutes, and stir at a rate of 130-160 rpm during the process;

[0042] S2: Take out the carbon fiber treated by S1 and immerse it in an acid solution prepared by 35-100 parts by weight of HNO3 and 100 parts by weight of deionized water. Add 0.2-1.0 parts by weight of nano boron nitride with a particle size of 20-50nm to the acid solution. Heat the acid solution to a boiling state and perform an oxidation etching treatment for 30-40 minutes to generate carboxyl functional groups and form micro-nano pits on the surface of the carbon fiber.

[0043] S3: After the oxidation treatment, the carbon fiber is repeatedly washed with deionized water, adding 100-200 parts by weight of deionized water each time, until the pH of the aqueous solution reaches 6-8 after washing, to remove residual Sn on the surface. 2+ HNO3, nano-BN debris and reaction byproducts;

[0044] S4: Transfer the cleaned carbon fibers to a drying device under nitrogen atmosphere protection, control the drying temperature at 110-210℃, and the drying time at 1-2 hours. During this period, maintain a nitrogen flow rate of 8-15 L / min per 10 parts by weight of carbon fibers. After drying, a surface coating of "Sn" is obtained. 2+ - Carbon fibers with nano-BN composite modified layers.

[0045] Preferably, the pretreated carbon fiber and aluminum-based alloy powder are in a mass ratio of 0.5:99.5 to 5:95.

[0046] Preferably, the ball mill rotation speed is 250-450 rpm.

[0047] Preferably, the pressing and heat preservation temperature is 200-400°C.

[0048] Preferably, the aluminum matrix alloy is selected from 6061, 5083 or 7075.

[0049] Preferably, the solution treatment and aging treatment are cooled by water cooling or oil cooling.

[0050] Technical Mechanism: The multifunctional chelation-adsorption mechanism of step S1 in this invention: S-2-hydroxyglutaric acid molecules contain hydroxyl and dicarboxyl groups, which can synergistically bind with Sn. 2+ The formation of coordination chelates, with their multi-coordination structures exhibiting higher thermodynamic stability, can effectively suppress Sn over a wider range. 2+ Hydrolysis; simultaneously, the π-electron cloud at the defect sites on the carbon fiber surface forms π-H bonds with the amino groups of the thiourea group in the complex ion, assisting electrostatic attraction to achieve uniform adsorption of the complex ion on the carbon fiber surface, avoiding Sn 2+ Local clustering phenomena have occurred.

[0051] S2 step oxidation-functional enhancement mechanism: HNO3 can oxidize the carbon fiber surface to generate carboxyl functional groups, providing hydrogen bonding sites for nano-BN; on the other hand, it can oxidize the residual thiourea group of S-2-hydroxyglutaric acid to sulfoxide group, and the sulfoxide group reacts with Sn... 2+ This allows for the formation of stronger coordination bonds, further stabilizing the Sn on the carbon fiber surface. 2+ The active layer; nano-BN forms a physical interlock with the micro-nano pits on the surface of carbon fiber through its own layered structure, and its high temperature resistance can protect the carbon fiber from excessive etching, ultimately achieving a triple effect of "modification-protection-strengthening".

[0052] Compared with the prior art, the present invention has the following significant technical effects:

[0053] 1) Significant weight reduction: Compared with cast iron, it can reduce weight, thereby reducing the unsprung mass of the wheels or the overall weight of the vehicle, improving dynamic response and fuel economy (or energy consumption).

[0054] 2) Improve wear resistance and hardness: Carbon fiber reinforcement, interface pretreatment and heat treatment processes significantly improve the material's hardness and surface wear resistance, extending its service life.

[0055] 3) Enhanced strength and fatigue resistance: Fiber reinforcement and good dispersion + interfacial bonding make it less prone to cracking, fracture or fatigue failure under alternating loads or high temperature conditions.

[0056] 4) Good heat dissipation performance: Carbon fiber has high thermal conductivity, and its good connection and dispersion can enhance the overall thermal conductivity; the aluminum matrix itself has good thermal conductivity; heat accumulation during braking is reduced, the temperature drops quickly, and high-temperature thermal decay is mitigated.

[0057] 5) Stable friction coefficient: The friction coefficient fluctuates little under complex environments such as repeated braking, high temperature, humidity, and dust.

[0058] 6) Good process controllability and economy: By combining powder + prebody + melt + heat treatment + casting / die casting, large-scale production is feasible, and the amount of carbon fiber used is not too high, so the cost can be controlled.

[0059] 7) Improved interface bonding and impact resistance: After composite modification, the carboxyl groups and sulfoxide groups on the carbon fiber surface work together to enhance the chemical bonding force with the aluminum matrix. The interface voids are greatly reduced during subsequent aluminum melt casting. Under the impact load of high-frequency braking, the brake disc is less prone to interface peeling, and the overall impact resistance and structural stability are significantly improved.

[0060] 8) High-temperature corrosion resistance and long-term performance optimization: The nano-BN protective layer can resist the high-temperature erosion of molten aluminum and reduce carbon fiber oxidation loss; S-2-hydroxyglutaric acid and Sn 2+ The chelate formed is not easily decomposed at high temperatures, which can maintain the surface activity of carbon fiber for a long time and extend the service life of brake discs; at the same time, the compound is easily soluble in water and leaves no residue after cleaning, avoiding interference with the performance of aluminum-based composite materials and meeting environmental protection process requirements. Detailed Implementation

[0061] The features of the present invention are further illustrated below through embodiments, but the scope of protection of this application is not limited to the embodiments.

[0062] Example 1: A method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material, comprising the following steps, in parts by weight:

[0063] (1) Preparation of aluminum-based alloy powder:

[0064] Weigh out 88 kg of aluminum (Al), 9 kg of silicon (Si), 2 kg of copper (Cu), 0.1 kg of magnesium (Mg), 0.2 kg of zinc (Zn), 0.2 kg of iron (Fe), 0.2 kg of manganese (Mn), 0.1 kg of nickel (Ni), 0.05 kg of titanium (Ti), and 0.1 kg of tin (Sn). All metal powders are industrial grade, with a particle size controlled between 50-100 μm. Mix them evenly to obtain aluminum-based alloy powder.

[0065] (2) Carbon fiber pretreatment:

[0066] Take 0.5 kg of carbon fiber (0.05 μm in diameter and 10 μm in length), place it in a nitrogen atmosphere furnace, heat to 400℃ and hold for 30 minutes, then allow it to cool naturally to room temperature; subsequently, perform chemical sensitization treatment as follows:

[0067] S1: Add 20kg SnCl2, 0.3kg S-2-hydroxyglutaric acid and 200kg deionized water to a glass reaction vessel and stir magnetically for 10 minutes until completely dissolved; immerse the cooled carbon fiber in the mixed solution and soak at 28°C for 12 minutes, stirring continuously at 130rpm during the process.

[0068] S2: Take out the carbon fiber after S1 treatment and immerse it in an acid solution prepared with 35kg HNO3 and 100kg deionized water. Add 0.2kg of nano boron nitride (particle size 20nm) to the acid solution and heat it until the acid solution boils. Maintain the boiling state for oxidative etching for 30 minutes to generate carboxyl functional groups on the surface of the carbon fiber and form micro-nano pits.

[0069] S3: After the oxidation treatment, the carbon fiber is transferred to deionized water for repeated washing. Each time, 100 kg of deionized water is added, stirred for 5 minutes, and then drained. This washing is repeated 3 times until the pH of the aqueous solution reaches 6-8, thus removing residual Sn from the surface. 2+ HNO3, nano-BN debris and reaction byproducts;

[0070] S4: Transfer the cleaned carbon fibers to a vacuum drying oven under nitrogen atmosphere protection, control the drying temperature at 110℃, and dry for 1 hour; during this period, nitrogen is supplied at a rate of 8L / min per 10kg of carbon fibers, corresponding to a nitrogen flow rate of 0.4L / min for 0.5kg of carbon fibers; after drying, a surface coating of "Sn" is obtained. 2+ - Carbon fibers with nano-BN" composite modified layers;

[0071] (3) Mixing and preforming:

[0072] 0.5 kg of pretreated carbon fiber and 99.5 kg of aluminum-based alloy powder (mass ratio 0.5:99.5) were added to an agate ball mill jar, and zirconia balls (ball-to-material ratio 10:1) were loaded. The mixture was ball-milled at 250 rpm for 30 minutes until homogeneous.

[0073] The mixture is transferred to a steel mold and pressed into shape under a nitrogen atmosphere at a pressure of 50 MPa. At the same time, the mold is heated to 200°C and held for 0.5 hours to make the powder bind together but not melt, thus obtaining a brake disc preform (200 mm in diameter and 30 mm in thickness).

[0074] (4) Melt immersion and casting:

[0075] A 6061 aluminum matrix alloy was selected, placed in a graphite crucible, heated to 650°C for melting, and held at that temperature for 0.5 hours under a nitrogen atmosphere to reduce oxidation, thus obtaining the melt.

[0076] Slowly place the preform into the melt and mechanically stir at 200 rpm for 3 minutes to ensure that the carbon fiber is evenly dispersed in the melt; preheat the mold to 400°C and maintain this temperature while pouring the aluminum melt containing carbon fiber into the mold, allowing it to flow naturally and level.

[0077] (5) Heat treatment:

[0078] The cast brake disc blank is subjected to solution treatment: heated to 480℃, held for 2 hours, and then water-cooled to room temperature;

[0079] After solution treatment, aging treatment is carried out: heat to 150℃, hold for 6 hours, then cool to room temperature in oil to complete the strengthening process;

[0080] (6) Machining and friction surface treatment:

[0081] The brake disc blank is machined by turning and milling using a CNC lathe, and mounting holes are drilled to achieve the final geometric dimensions (diameter 200mm, thickness 28mm). The friction surface is then finely ground to control the surface roughness Ra to 1.0μm, resulting in a high-performance brake disc.

[0082] Example 2: A method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material, comprising the following steps, in parts by weight:

[0083] (1) Preparation of aluminum-based alloy powder:

[0084] Weigh out 90 kg of aluminum (Al), 10 kg of silicon (Si), 3 kg of copper (Cu), 0.3 kg of magnesium (Mg), 0.4 kg of zinc (Zn), 0.4 kg of iron (Fe), 0.3 kg of manganese (Mn), 0.2 kg of nickel (Ni), 0.2 kg of titanium (Ti), and 0.2 kg of tin (Sn). The metal powders have a particle size of 50-100 μm. Mix them evenly to obtain aluminum-based alloy powder.

[0085] (2) Carbon fiber pretreatment:

[0086] Take 2 kg of carbon fiber (2 μm in diameter and 40 μm in length), place it in a nitrogen atmosphere furnace, heat it to 450℃ and hold it for 40 minutes, then let it cool naturally; subsequently, perform chemical sensitization treatment:

[0087] S1: Add 27kg SnCl2, 0.7kg S-2-hydroxyglutaric acid and 230kg deionized water to the reaction vessel, stir to dissolve, and then immerse the carbon fiber in the solution. Soak at 30℃ for 15 minutes with a stirring speed of 140rpm.

[0088] S2: Immerse the carbon fiber in an acid solution prepared with 55kg HNO3 and 100kg deionized water, add 0.5kg of nano boron nitride (particle size 30nm), and heat to boiling for 33 minutes for oxidation etching.

[0089] S3: Wash the carbon fiber with 130kg of deionized water, stirring for 6 minutes each time, for a total of 4 washes, until the pH of the aqueous solution reaches 6-8;

[0090] S4: Place the carbon fiber in a nitrogen-protected drying oven and dry it at 140℃ for 1.3 hours. The nitrogen flow rate is calculated at 10L / min per 10kg of carbon fiber, which corresponds to a flow rate of 2L / min for 2kg of carbon fiber. After drying, modified carbon fiber is obtained.

[0091] (3) Mixing and preforming:

[0092] 2 kg of modified carbon fiber and 98 kg of aluminum-based alloy powder (mass ratio 1.5:98.5) were added to a ball mill jar and ball milled at 300 rpm for 60 minutes.

[0093] Under a nitrogen atmosphere, the mixture was pressed into shape at a pressure of 100 MPa, and the mold was heated to 280°C and held for 1 hour to obtain a brake disc preform (diameter 220 mm, thickness 32 mm).

[0094] (4) Melt immersion and casting:

[0095] A 5083 aluminum matrix alloy was selected, and the melting temperature was 670℃. The melt was then held in a nitrogen atmosphere for 1 hour to obtain the melt.

[0096] Add the pre-mixed block to the melt and stir at 500 rpm for 5 minutes; preheat the mold to 450°C and pour the melt.

[0097] (5) Heat treatment:

[0098] Solution treatment: Hold at 500℃ for 3 hours, then cool to room temperature with oil;

[0099] Aging treatment: Hold at 180℃ for 8 hours, then water-cool to room temperature;

[0100] (6) Machining and friction surface treatment:

[0101] The brake disc is machined to its final size (220mm in diameter and 30mm in thickness), and the surface roughness Ra is 1.8μm after fine grinding of the friction surface, thus obtaining the finished brake disc.

[0102] Example 3: A method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material, comprising the following steps, in parts by weight:

[0103] (1) Preparation of aluminum-based alloy powder:

[0104] Weigh out 93 kg of aluminum (Al), 12 kg of silicon (Si), 4 kg of copper (Cu), 0.6 kg of magnesium (Mg), 0.7 kg of zinc (Zn), 0.7 kg of iron (Fe), 0.4 kg of manganese (Mn), 0.4 kg of nickel (Ni), 0.4 kg of titanium (Ti), and 0.25 kg of tin (Sn). The metal powders have a particle size of 50-100 μm. Mix them evenly to obtain aluminum-based alloy powder.

[0105] (2) Carbon fiber pretreatment:

[0106] Take 3.5 kg of carbon fiber (4 μm in diameter and 70 μm in length), place it in a nitrogen atmosphere furnace, heat it to 550 °C and hold it at that temperature for 50 minutes, then cool it and chemically sensitize it.

[0107] S1: Mix 35kg SnCl2, 1.1kg S-2-hydroxyglutaric acid and 270kg deionized water, immerse the mixture in carbon fiber, soak at 33℃ for 19 minutes, and stir at 150rpm.

[0108] S2: Immerse the carbon fiber in an acid solution of 85kg HNO3 and 100kg deionized water, add 0.8kg of nano boron nitride (particle size 40nm), and etch by boiling for 37 minutes.

[0109] S3: Wash 5 times with 180kg of deionized water, stirring for 8 minutes each time, until the pH of the aqueous solution reaches 6-8;

[0110] S4: Dry at 180℃ for 1.7 hours in a nitrogen-protected drying oven. The nitrogen flow rate is calculated at 13L / min per 10kg of carbon fiber, and the corresponding flow rate for 3.5kg of carbon fiber is 4.55L / min. Modified carbon fiber is obtained after drying.

[0111] (3) Mixing and preforming:

[0112] Add 3.5 kg of modified carbon fiber and 96.5 kg of aluminum-based alloy powder (mass ratio 3.5:96.5) to a ball mill jar and ball mill at 400 rpm for 90 minutes.

[0113] Under a nitrogen atmosphere, the pre-block was pressed at 160 MPa and the mold was kept at 350℃ for 1.5 hours to obtain a pre-block (diameter 240 mm, thickness 35 mm).

[0114] (4) Melt immersion and casting:

[0115] A 7075 aluminum matrix alloy was selected, and the melting temperature was 700℃. The mixture was then held in a nitrogen atmosphere for 1.5 hours to obtain the melt.

[0116] After adding the pre-block to the melt, stir at 1000 rpm for 8 minutes, and pour into the mold at 550℃.

[0117] (5) Heat treatment:

[0118] Solution treatment: Hold at 530℃ for 5 hours, then cool to room temperature with water;

[0119] Aging treatment: Hold at 220℃ for 10 hours, then cool to room temperature;

[0120] (6) Machining and friction surface treatment:

[0121] The brake disc is machined to its final dimensions (240mm in diameter and 33mm in thickness), with the surface roughness Ra of the friction surface controlled at 2.5μm, to obtain the finished brake disc.

[0122] Example 4: A method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material, comprising the following steps, in parts by weight:

[0123] (1) Preparation of aluminum-based alloy powder:

[0124] Weigh out 95 kg of aluminum (Al), 13 kg of silicon (Si), 5 kg of copper (Cu), 0.8 kg of magnesium (Mg), 1.0 kg of zinc (Zn), 1.0 kg of iron (Fe), 0.5 kg of manganese (Mn), 0.5 kg of nickel (Ni), 0.5 kg of titanium (Ti), and 0.3 kg of tin (Sn). The metal powders have a particle size of 50-100 μm. Mix them evenly to obtain aluminum-based alloy powder.

[0125] (2) Carbon fiber pretreatment:

[0126] Take 5 kg of carbon fiber (5.0 μm in diameter and 100 μm in length), place it in a nitrogen atmosphere furnace, heat to 600℃ and hold for 60 minutes, then cool and chemically sensitize:

[0127] S1: Dissolve 40kg SnCl2, 1.4kg S-2-hydroxyglutaric acid in 300kg deionized water, immerse the carbon fiber in the solution, soak at 35℃ for 22 minutes, stirring at 160rpm.

[0128] S2: Immerse the carbon fiber in an acid solution of 100kg HNO3 and 100kg deionized water, add 1.0kg of nano boron nitride (particle size 50nm), and heat to boiling for 40 minutes for oxidation etching.

[0129] S3: Wash with 200kg of deionized water 6 times, stirring for 10 minutes each time, until the pH of the aqueous solution reaches 6-8 after washing;

[0130] S4: Place the carbon fiber in a nitrogen-protected drying oven and dry it at 210℃ for 2 hours. The nitrogen flow rate is calculated at 15L / min per 10kg of carbon fiber, and the flow rate corresponding to 5kg of carbon fiber is 7.5L / min. After drying, the modified carbon fiber is obtained.

[0131] (3) Mixing and preforming:

[0132] Add 5 kg of modified carbon fiber and 95 kg of aluminum-based alloy powder (mass ratio 5:95) to a ball mill jar and ball mill at 450 rpm for 120 minutes to mix evenly.

[0133] Under a nitrogen atmosphere, the mixture was pressed into shape at a pressure of 200 MPa, while the mold was heated to 400°C and held for 2 hours to obtain a brake disc preform (diameter 260 mm, thickness 38 mm).

[0134] (4) Melt immersion and casting:

[0135] A 6061 aluminum matrix alloy was selected, placed in a graphite crucible, heated to 720°C for melting, and held at that temperature for 2 hours under a nitrogen atmosphere to reduce oxidation, thus obtaining the melt.

[0136] Slowly add the preform block to the melt and mechanically stir at 1500 rpm for 10 minutes to ensure uniform dispersion of the carbon fiber; preheat the mold to 600°C and maintain this temperature while pouring the melt into the mold, allowing it to flow naturally and level.

[0137] (5) Heat treatment:

[0138] Solution treatment: Heat the blank to 550℃ and hold for 6 hours, then cool it to room temperature with oil;

[0139] Aging treatment: Heat to 250℃, keep warm for 12 hours, then cool to room temperature with water;

[0140] (6) Machining and friction surface treatment:

[0141] The brake disc is machined to its final geometric dimensions (260mm in diameter and 36mm in thickness) by turning, milling, and drilling using a CNC machining center. The friction surface is then precision ground to control the surface roughness Ra to 3.0μm, resulting in a high-performance carbon fiber reinforced aluminum matrix composite brake disc.

[0142] Comparative Example 1: A method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material, comprising the following steps, in parts by mass:

[0143] (1) Preparation of aluminum-based alloy powder:

[0144] Weigh out 88 kg of aluminum (Al), 9 kg of silicon (Si), 2 kg of copper (Cu), 0.1 kg of magnesium (Mg), 0.2 kg of zinc (Zn), 0.2 kg of iron (Fe), 0.2 kg of manganese (Mn), 0.1 kg of nickel (Ni), 0.05 kg of titanium (Ti), and 0.1 kg of tin (Sn). All metal powders are industrial grade, with a particle size controlled between 50-100 μm. Mix them evenly to obtain aluminum-based alloy powder.

[0145] (2) Carbon fiber pretreatment:

[0146] Take 0.5 kg of carbon fiber (0.05 μm in diameter and 10 μm in length), place it in a nitrogen atmosphere furnace, heat to 400℃ and hold for 30 minutes, then allow it to cool naturally to room temperature; subsequently, perform chemical sensitization treatment as follows:

[0147] S1: Add 20kg SnCl2 and 200kg deionized water to a glass reaction vessel and stir magnetically for 10 minutes until completely dissolved; immerse the cooled carbon fiber in the mixed solution and soak at 28°C for 12 minutes, stirring continuously at 130rpm during the process.

[0148] S2: Take out the carbon fiber after S1 treatment and immerse it in an acid solution prepared with 35kg HNO3 and 100kg deionized water. Add 0.2kg of nano boron nitride (particle size 20nm) to the acid solution and heat it until the acid solution boils. Maintain the boiling state for oxidative etching for 30 minutes to generate carboxyl functional groups on the surface of the carbon fiber and form micro-nano pits.

[0149] S3: After the oxidation treatment, the carbon fiber is transferred to deionized water for repeated washing. Each time, 100 kg of deionized water is added, stirred for 5 minutes, and then drained. This washing is repeated 3 times until the pH of the aqueous solution reaches 6-8, thus removing residual Sn from the surface. 2+ HNO3, nano-BN debris and reaction byproducts;

[0150] S4: Transfer the cleaned carbon fibers to a vacuum drying oven under nitrogen atmosphere protection, control the drying temperature at 110℃, and dry for 1 hour; during this period, nitrogen is supplied at a rate of 8L / min per 10kg of carbon fibers, corresponding to a nitrogen flow rate of 0.4L / min for 0.5kg of carbon fibers; after drying, a surface coating of "Sn" is obtained. 2+ - Carbon fibers with nano-BN" composite modified layers;

[0151] (3) Mixing and preforming:

[0152] 0.5 kg of pretreated carbon fiber and 99.5 kg of aluminum-based alloy powder (mass ratio 0.5:99.5) were added to an agate ball mill jar, and zirconia balls (ball-to-material ratio 10:1) were loaded. The mixture was ball-milled at 250 rpm for 30 minutes until homogeneous.

[0153] The mixture is transferred to a steel mold and pressed into shape under a nitrogen atmosphere at a pressure of 50 MPa. At the same time, the mold is heated to 200°C and held for 0.5 hours to make the powder bind together but not melt, thus obtaining a brake disc preform (200 mm in diameter and 30 mm in thickness).

[0154] (4) Melt immersion and casting:

[0155] A 6061 aluminum matrix alloy was selected, placed in a graphite crucible, heated to 650°C for melting, and held at that temperature for 0.5 hours under a nitrogen atmosphere to reduce oxidation, thus obtaining the melt.

[0156] Slowly place the preform into the melt and mechanically stir at 200 rpm for 3 minutes to ensure that the carbon fiber is evenly dispersed in the melt; preheat the mold to 400°C and maintain this temperature while pouring the aluminum melt containing carbon fiber into the mold, allowing it to flow naturally and level.

[0157] (5) Heat treatment:

[0158] The cast brake disc blank is subjected to solution treatment: heated to 480℃, held for 2 hours, and then water-cooled to room temperature;

[0159] After solution treatment, aging treatment is carried out: heat to 150℃, hold for 6 hours, then cool to room temperature in oil to complete the strengthening process;

[0160] (6) Machining and friction surface treatment:

[0161] The brake disc blank is machined by turning and milling using a CNC lathe, and mounting holes are drilled to achieve the final geometric dimensions (diameter 200mm, thickness 28mm). The friction surface is then finely ground to control the surface roughness Ra to 1.0μm, resulting in a high-performance brake disc.

[0162] Comparative Example 2: A method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material, comprising the following steps, by mass:

[0163] (1) Preparation of aluminum-based alloy powder:

[0164] Weigh out 88 kg of aluminum (Al), 9 kg of silicon (Si), 2 kg of copper (Cu), 0.1 kg of magnesium (Mg), 0.2 kg of zinc (Zn), 0.2 kg of iron (Fe), 0.2 kg of manganese (Mn), 0.1 kg of nickel (Ni), 0.05 kg of titanium (Ti), and 0.1 kg of tin (Sn). All metal powders are industrial grade, with a particle size controlled between 50-100 μm. Mix them evenly to obtain aluminum-based alloy powder.

[0165] (2) Carbon fiber pretreatment:

[0166] Take 0.5 kg of carbon fiber (0.05 μm in diameter and 10 μm in length), place it in a nitrogen atmosphere furnace, heat to 400℃ and hold for 30 minutes, then allow it to cool naturally to room temperature; subsequently, perform chemical sensitization treatment as follows:

[0167] S1: Add 20kg SnCl2, 0.3kg S-2-hydroxyglutaric acid and 200kg deionized water to a glass reaction vessel and stir magnetically for 10 minutes until completely dissolved; immerse the cooled carbon fiber in the mixed solution and soak at 28°C for 12 minutes, stirring continuously at 130rpm during the process.

[0168] S2: Take out the carbon fiber treated in S1 and immerse it in an acid solution prepared with 35kg HNO3 and 100kg deionized water. Heat the acid solution until it boils and maintain the boiling state for 30 minutes to oxidize and etch, generating carboxyl functional groups and forming micro-nano pits on the surface of the carbon fiber.

[0169] S3: After the oxidation treatment, the carbon fiber is transferred to deionized water for repeated washing. Each time, 100 kg of deionized water is added, stirred for 5 minutes, and then drained. This washing is repeated 3 times until the pH of the aqueous solution reaches 6-8, thus removing residual Sn from the surface. 2+ HNO3 and reaction byproducts;

[0170] S4: Transfer the cleaned carbon fiber to a vacuum drying oven under nitrogen atmosphere protection, control the drying temperature at 110℃ and the drying time at 1 hour; during the drying process, nitrogen is supplied at a rate of 8L / min per 10kg of carbon fiber, corresponding to a nitrogen flow rate of 0.4L / min for 0.5kg of carbon fiber; after drying, carbon fiber with composite modified layer is obtained.

[0171] (3) Mixing and preforming:

[0172] 0.5 kg of pretreated carbon fiber and 99.5 kg of aluminum-based alloy powder (mass ratio 0.5:99.5) were added to an agate ball mill jar, and zirconia balls (ball-to-material ratio 10:1) were loaded. The mixture was ball-milled at 250 rpm for 30 minutes until homogeneous.

[0173] The mixture is transferred to a steel mold and pressed into shape under a nitrogen atmosphere at a pressure of 50 MPa. At the same time, the mold is heated to 200°C and held for 0.5 hours to make the powder bind together but not melt, thus obtaining a brake disc preform (200 mm in diameter and 30 mm in thickness).

[0174] (4) Melt immersion and casting:

[0175] A 6061 aluminum matrix alloy was selected, placed in a graphite crucible, heated to 650°C for melting, and held at that temperature for 0.5 hours under a nitrogen atmosphere to reduce oxidation, thus obtaining the melt.

[0176] Slowly place the preform into the melt and mechanically stir at 200 rpm for 3 minutes to ensure that the carbon fiber is evenly dispersed in the melt; preheat the mold to 400°C and maintain this temperature while pouring the aluminum melt containing carbon fiber into the mold, allowing it to flow naturally and level.

[0177] (5) Heat treatment:

[0178] The cast brake disc blank is subjected to solution treatment: heated to 480℃, held for 2 hours, and then water-cooled to room temperature;

[0179] After solution treatment, aging treatment is carried out: heat to 150℃, hold for 6 hours, then cool to room temperature in oil to complete the strengthening process;

[0180] (6) Machining and friction surface treatment:

[0181] The brake disc blank is machined by turning and milling using a CNC lathe, and mounting holes are drilled to achieve the final geometric dimensions (diameter 200mm, thickness 28mm). The friction surface is then finely ground to control the surface roughness Ra to 1.0μm, resulting in a high-performance brake disc.

[0182] Test methods and results:

[0183] 1. Hardness test (micro Vickers hardness)

[0184] Sample preparation: Cut a cross-sectional sample near the friction surface and polish it to a mirror finish; perform 10 measurements at HV0.5 (500gf) or HV1 (1kgf) and take the average.

[0185] Table 1: Hardness test results of each embodiment and comparative example

[0186]

[0187] 2. Stretching (room temperature)

[0188] Method / Sample: Cut standard miniature tensile specimens from the disc (or a plate pattern permissible by powder metallurgy, as per standard requirements); room temperature, span, and rate as per ASTM E8 requirements; average of 3 specimens per group.

[0189] Table 2: Tensile test results of each embodiment and comparative example

[0190]

[0191] 3. Wear / friction resistance

[0192] Equipment / Parameters:

[0193] Testing equipment: Laboratory pin-disc testing machine;

[0194] Load: 10N (a medium load used to characterize the friction disc-slider contact);

[0195] Rotational speed / linear velocity: 0.2 m / s (corresponding rotational speed converted to radius);

[0196] Sliding distance: 1000m (or cumulative sliding time 5000s);

[0197] For grinding: the sample (disc) and the standard steel ball or standard plate (materials consistent or according to reference);

[0198] Environment: Room temperature 23±2°C, humidity 40–60%;

[0199] Data: Real-time recording of the friction coefficient, weighing before and after the test to determine mass loss (mg), and also measuring wear volume.

[0200] Results (average friction coefficient µ; mass loss mg / 1000m)

[0201] Table 3: Abrasion / friction test results of each embodiment and comparative example

[0202]

[0203] 4. Thermal properties (thermal diffusivity / thermal conductivity)

[0204] Key points of the method: Cut circular samples (usually 10–12 mm in diameter and 1–3 mm in thickness), spray black paint on both sides to absorb laser pulses; measure the thermal diffusivity α using laser flash, and then calculate the thermal conductivity k = α·ρ·c_p based on density ρ and specific heat c_p (specific heat is calculated using differential scanning calorimetry or literature values).

[0205] Results (typical k value, W / m·K)

[0206] Table 4: Thermal performance test results of each embodiment and comparative example

[0207]

[0208] Wear resistance / hardness / durability: The example demonstrates superior performance compared to the comparative example in both hardness and wear rate, indicating that carbon fiber modification and good interface treatment can both improve surface hardness and reduce wear loss. Thermal conductivity proves that this method is beneficial in reducing peak disk temperature and thermal gradient, thereby suppressing thermal cracking and thermal decay.

[0209] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for manufacturing a high performance brake disc of carbon fiber reinforced aluminum matrix composite material, characterized in that, The method comprises the following steps, in terms of mass fraction: (1) Aluminum-based alloy powder preparation: Aluminum Al: 88.0-95.0 parts Silicon Si: 9.0-13.0 parts Copper Cu: 2.0-5.0 parts Magnesium Mg: 0.1-0.8 parts Zinc Zn: 0.2-1.0 parts Iron Fe: 0.2-1.0 parts Manganese Mn: 0.2-0.5 parts Nickel Ni: ≤0.5 parts Titanium Ti: 0.05-0.5 parts Tin Sn: ≤0.3 parts; (2) Carbon fiber pretreatment: 0.5-5.0 parts of carbon fiber is heated to 400-600°C for 30-60 minutes in a nitrogen atmosphere, and then cooled; followed by chemical sensitization treatment; (3) Mixing and pre-forming The pretreated carbon fiber and aluminum-based alloy powder are mixed by ball milling at a mass ratio, and the mixing time is 30-120 minutes; The mixture is pressed into a pre-form block under a pressure of 50-200 MPa in a nitrogen atmosphere, and the size can be predetermined according to the size of the brake disc; the pressing is kept for 0.5-2 hours to make the powder bond but not melt, and a pre-form is obtained; (4) Melt immersion and pouring The aluminum matrix alloy is smelted at a temperature of 650-720°C; the smelting should be treated in a nitrogen atmosphere or vacuum to reduce oxidation, and the holding time is 0.5-2 hours to obtain a melt; The pre-form is slowly added to the melt, and mechanical stirring is performed to uniformly disperse the fibers, with a stirring speed of 200-1500 rpm; the stirring time is 3-10 minutes; the mold is preheated to a temperature of 400-600°C; and the mold is kept at this temperature during pouring; (5) Heat treatment Solution treatment: temperature 480-550°C, holding time 2-6 hours; Ageing treatment: temperature 150-250°C, holding time 6-12 hours; (6) Processing and friction surface treatment Processing to the final geometric size, including turning, milling, and drilling; the friction surface roughness Ra is controlled to be 1.0-3.0 µm; The chemical sensitization treatment is prepared by immersing SnCl2, S-2-hydroxyglutaric acid, and carbon fiber, followed by oxidation etching treatment with HNO3, deionized water, and nano boron nitride, and then washing with deionized water until the pH of the aqueous solution after washing reaches 6-8, and then drying.

2. The method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material according to claim 1, characterized in that: The diameter of the carbon fiber is 0.05-5.0 µm, and the fiber length is 10-100 µm.

3. The method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material according to claim 1, characterized in that: The steps of the chemical sensitization treatment are: S1: According to the weight fraction range, 20-40 parts by weight of SnCl2, 0.3-1.4 parts by weight of S-2-hydroxyglutaric acid, and 200-300 parts by weight of deionized water are added to a reaction container, stirred uniformly, then 10-20 parts by weight of carbon fiber is immersed in the mixed solution, and soaked at 28-35°C for 12-22 minutes, with stirring at a speed of 130-160 rpm during the soaking; S2: The carbon fiber treated by S1 is taken out and immersed in an acid solution prepared from 35-100 parts by weight of HNO3 and 100 parts by weight of deionized water, 0.2-1.0 parts by weight of nano boron nitride with a particle size of 20-50 nm is added to the acid solution, the acid solution is heated to boiling state, and oxidation etching treatment is performed for 30-40 minutes to generate carboxyl functional groups on the surface of the carbon fiber and form micro-nano pits. S3: After the end of the oxidation treatment, the carbon fibers are repeatedly washed with deionized water, 100-200 parts by weight of deionized water are added each time until the pH of the aqueous solution after washing reaches 6-8, and the surface residual Sn is removed 2+ , HNO3, nano-BN debris and reaction by-products; S4: The cleaned carbon fiber is transferred to a drying device under nitrogen atmosphere protection, the drying temperature is controlled at 110-210°C, the drying time is 1-2 hours, and the nitrogen flow is supplied at a ratio of 8-15 L / min per 10 parts by weight of carbon fiber during the drying process. After drying, the surface is covered with "Sn 2+ carbon fiber with a nano-BN" composite modified layer.

4. The method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material according to claim 1, characterized in that: The pre-treated carbon fibers are mixed with the aluminum-based alloy powder in a mass ratio of 0.5:99.5 to 5:

95.

5. The method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material according to claim 1, characterized in that: The ball milling rotation speed is 250-450 rpm.

6. The method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material according to claim 1, characterized in that: The pressing holding temperature is 200-400 °C.

7. The method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material according to claim 1, characterized in that: The aluminum matrix alloy is selected from 6061, 5083 or 7075.

8. The method for preparing a high-performance brake disc made of carbon fiber reinforced aluminum matrix composite material according to claim 1, characterized in that: The solid solution treatment and aging treatment cooling method is water cooling or oil cooling.

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