Method for manufacturing a light-weight high-strength brake disc

Abstract

The application discloses a preparation method of a light high-strength brake disc and relates to the field of manufacturing of automobile braking parts. The brake disc is composed of a light metal inner layer and a high-strength ceramic surface layer. The brake disc is prepared through the processes of plasma spraying, heat treatment, mechanical processing and wear-resistant coating. The application realizes light weight, and also significantly improves the strength, the thermal fatigue life and the heat dissipation efficiency. The application has the advantages of optimized structure, mature process and moderate cost, and is particularly suitable for upgrading of the braking systems of electric vehicles and high-performance passenger vehicles.

Description

Technical Field

[0001] The invention relates to the field of automobile brake parts manufacturing, in particular to a method for preparing a lightweight and high-strength brake disc. Background Art

[0002] Traditional automotive brake discs are primarily manufactured from gray cast iron, a material of choice due to its excellent thermal conductivity, stable high-temperature strength, and good wear resistance. However, gray cast iron's high density increases the vehicle's unsprung mass, negatively impacting fuel efficiency and handling. Furthermore, it is susceptible to thermal warping and thermal fatigue cracking under high-temperature braking conditions, resulting in reduced braking performance and a shortened service life.

[0003] To reduce vehicle weight and improve energy efficiency and range, particularly in electric vehicles, the industry is conducting extensive research into lightweight brake disc materials. Aluminum-based metal matrix composites (AMCs) and hybrid metal matrix composites (HAMCs) have emerged as viable alternatives. Research has shown that aluminum alloy-based composites, by incorporating hard ceramic reinforcements such as silicon carbide (SiC) and alumina (Al2O3), can significantly improve wear resistance, thermal conductivity, and strength. These composites weigh approximately 40-50% of cast iron discs while maintaining or improving thermal impedance and crack resistance.

[0004] Meanwhile, carbon fiber ceramic composites (C / SiC or C / C) are widely used in high-performance and luxury vehicles. Initially used in aviation and Formula One racing, these ceramic-based composite brake discs have gradually entered the high-end civilian vehicle market since the 2000s. C / SiC discs produced by the Brembo-SGL joint venture, for example, offer exceptional thermal stability, wear resistance, a nearly constant coefficient of friction, an extremely long lifespan (up to 150,000 kilometers or more), high resistance to thermal degradation, and weight reduction advantages (approximately 50%). However, their complex and lengthy manufacturing cycle (typically around 20 days) and high cost have limited their widespread adoption.

[0005] Based on this situation, modern brake disc design is gradually moving towards a dual-layer composite structure—creating a composite interface between a lightweight metal inner layer and a high-strength, heat-resistant ceramic outer layer. This reduces component weight while balancing heat resistance, wear resistance, and mechanical strength. Compared to traditional single-layer AMC or CMC (ceramic matrix composite) systems, this structure leverages the advantages of each, mitigating thermal expansion differences and thermal fatigue cracking issues between the materials.

[0006] Although studies have reported on the application of aluminum-based composite materials in brake discs, and a large number of studies have described the performance advantages of ceramic-based composite brake discs, there is no mature public technology for the systematic manufacturing method of preparing a double-layer structure brake disc between the inner layer of lightweight metal and the outer layer of high-strength ceramic through thermal spraying, injection molding or other composite methods. In particular, there is a lack of comprehensive process guidance in spraying thickness control, heat treatment interface bonding, micro-bonding structure optimization, and the coordination of ventilation hole structure and heat dissipation performance. This makes it difficult for existing technologies to achieve a comprehensive balance between lightweighting, strength improvement, thermal fatigue tolerance and manufacturing cost. Summary of the Invention

[0007] Based on the issues raised in the aforementioned background technology, this invention proposes a method for producing a lightweight, high-strength brake disc. This method creates a dual-layer composite structure by combining a lightweight metal substrate with a high-strength ceramic surface layer through controlled spraying, followed by interface optimization heat treatment, machining, and the addition of a ceramic coating. This method offers complementary advantages in terms of quality, strength, thermal fatigue life, and heat dissipation efficiency, representing a new direction for innovation in lightweight brake systems.

[0008] A method for preparing a lightweight, high-strength brake disc comprises the following steps, calculated in parts by mass:

[0009] 1) Preparation of lightweight inner metal matrix:

[0010] 100 parts of aluminum alloy A356 were melted and cast, and then aged for 4-5 hours to obtain the inner disk body;

[0011] 2) Surface composite material coating:

[0012] Prepare carbon-ceramic composite powder, calculated by mass: 60-70 parts of carbon fiber powder, 15-25 parts of carbon powder, and 10-20 parts of silicon carbide powder;

[0013] The powder is sprayed on the surface of the inner disc by plasma spraying method, with the spraying thickness controlled at 2.0-4.0mm, the spraying speed at 10-15g / min, and the spraying distance at 80-100mm;

[0014] 3) Intermediate heat treatment and interface bonding:

[0015] The coated inner disc body is annealed under inert gas protection for 1.5 to 3 hours to allow the surface powder to be preliminarily sintered and form a metal-ceramic interface bond with the substrate.

[0016] 4) Overall heat treatment:

[0017] After quenching the composite in oil to room temperature, tempering and holding for 3 to 5 hours to optimize the interface bonding strength and residual stress;

[0018] 5) Machining:

[0019] The numerical control turning and milling is adopted to the final diameter tolerance ±0.05mm, the thickness is processed to 28-32mm, and the flatness is ≤0.02mm; the cooling cutting fluid is water-based emulsion during the processing;

[0020] 6) surface ceramic coating treatment:

[0021] The alumina or silicon carbide ceramic coating is sprayed, the coating composition is 95 parts of Al2O3 or SiC powder and 5 parts of binder by mass fraction, the spraying thickness is controlled to be 30-70µm, the solidification temperature is 250-300℃, and the holding time is 1-2h.

[0022] As a further scheme of the application: the silicon content in the aluminum alloy A356 is 7.0-7.5wt%, and the magnesium content is 0.2-0.3wt%.

[0023] As a further scheme of the application: the aging treatment temperature is 210-220℃.

[0024] As a further scheme of the application: the carbon fiber powder particle size is 50-100µm, the carbon powder particle size is 20-50µm, and the silicon carbide particle size is 2-5µm.

[0025] As a further scheme of the application: the plasma spraying gas composition is Ar / H2 mixed gas, and the gas flow is 50-70L / min.

[0026] As a further scheme of the application: the inert gas is nitrogen or argon.

[0027] As a further scheme of the application: the annealing temperature is 500-600℃.

[0028] As a further scheme of the application: the tempering holding temperature is 320-360℃.

[0029] As a further scheme of the application: the preparation method of the binder is:

[0030] Raw material mixing and activation: 40-50 parts of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 8000-10000, 15-20 parts of vinyltriethoxysilane, 0.5-0.9 parts of vinyl ferrocene are added into a high-speed mixer, stirred at 800-1000r / min at 80-90℃ for 30-40 minutes, and 10-15 parts of nano silicon dioxide and 0.08-0.26 parts of octavinyl octasilsesquioxane (CAS: 69655-76-1) are added at the same time to complete the premixing and preliminary dispersion of inorganic particles;

[0031] Cross-linking reaction: Add 2-3 parts of di-tert-butyl peroxide to the mixed system, raise the temperature to 110-120°C, maintain stirring at 600-700 r / min for 2-2.5 hours, and form a network structure through the double bond addition reaction initiated by free radicals, while achieving chemical bonding between the silane coupling agent and nano-silica;

[0032] Product treatment: After the reaction system is naturally cooled to room temperature, it is ground using a three-roll mill to a particle size of ≤5 μm to obtain the binder.

[0033] Reaction Mechanism: Premixing and Activation: The hydroxyl groups of hydroxyl-terminated polydimethylsiloxane and the alkoxy groups of vinyltriethoxysilane undergo initial condensation at 80-90°C. The double bonds of vinylferrocene and the multiple vinyl groups of octavinylsilsesquioxane are thermally activated. The hydroxyl groups on the surface of the nanosilica and the active groups of octavinylsilsesquioxane are affinity-bound through intermolecular forces. High-speed stirring achieves uniform dispersion of the components, providing abundant reaction sites for subsequent cross-linking reactions. Cross-linking and Strengthening: The free radicals produced by the decomposition of di-tert-butyl peroxide initiate addition polymerization of the vinyl groups of vinyltriethoxysilane, vinylferrocene, and octavinylsilsesquioxane. The cage-like structure of octavinylsilsesquioxane serves as a cross-linking node, forming a denser three-dimensional network. Simultaneously, the nanosilica covalently bonds with the siloxane segments, further strengthening the "organic-inorganic" interpenetrating network. After cooling, solidification, and grinding, a stable product is formed.

[0034] High temperature resistance and optimized interface bonding: The siloxane cage structure of octavinylsilsesquioxane works synergistically with vinylferrocene and siloxane to reduce the weight loss rate of the adhesive during long-term use above 300°C; its multi-vinyl structure increases the cross-linking points with the substrate and ceramic powder, improving the adhesion of the coating, making it more adaptable to the high-temperature working environment of the brake disc and effectively preventing coating peeling.

[0035] Improved mechanical properties and thermal shock resistance: The cage structure of octavinylsilsesquioxane enhances network rigidity. Combined with the nano-reinforcement effect of nano-silica, the coating hardness (HV) and wear resistance are improved; the denser network structure can better buffer the stress caused by temperature changes, ensuring the long-term stable operation of the brake disc.

[0036] Technical effect: This method adopts a double-layer structure design of lightweight metal matrix + high-strength ceramic composite surface, combining interface optimization heat treatment with mechanical processing control, which not only reduces the mass but also significantly improves the strength, thermal fatigue life and heat dissipation efficiency; at the same time, it avoids the high manufacturing cost and long cycle of pure ceramic materials, and achieves a balance between comprehensive performance and manufacturing feasibility. DETAILED DESCRIPTION

[0037] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application and not to limit the present application.

[0038] Example 1: A method for preparing a lightweight high-strength brake disc, comprising the following steps:

[0039] Raw materials and parameters:

[0040] Aluminum alloy A356 (silicon content 7.0wt%, magnesium content 0.2wt%): 100 kg;

[0041] Carbon ceramic composite powder: carbon fiber powder 60 kg (particle size 50 pm), carbon powder 15 kg (particle size 20 pm), silicon carbide powder 10 kg (particle size 2 pm);

[0042] Surface ceramic coating raw material: 95 kg Al2O3 powder and 5 kg binder;

[0043] Preparation of lightweight inner layer metal matrix (step 1): 100 kg of aluminum alloy A356 is melted and cast, and is subjected to aging treatment at 210°C for 4h to obtain an inner layer disc body;

[0044] Surface layer composite material coating (step 2): the above carbon ceramic composite powder is sprayed on the surface of the inner layer disc body by plasma spraying method, the spraying thickness is controlled to be 2.0 mm, the spraying speed is 10 g / min, the spraying distance is 80 mm, the plasma spraying gas is Ar / H2 mixed gas, and the gas flow is 50 L / min;

[0045] Intermediate heat treatment and interface bonding (step 3): under nitrogen protection, annealing at 500°C for 1.5h to make the surface layer powder preliminarily sintered and form a metal-ceramic interface bonding with the matrix;

[0046] Overall heat treatment (step 4): quenching to room temperature in oil, and then tempering at 320°C for 3h to optimize the interface bonding strength and residual stress;

[0047] Mechanical processing (step 5): numerical control turning and milling to the final diameter tolerance ±0.05 mm, thickness processing to 28 mm, flatness ≤0.02 mm; the cooling cutting fluid in the processing process is water-based emulsion;

[0048] Surface ceramic coating treatment (step 6): spraying a coating composed of 95 kg Al2O3 powder and 5 kg binder, the spraying thickness is controlled to be 30 pm, and solidification is carried out at 250°C for 1h.

[0049] Preparation method of the binder:

[0050] Raw material mixing and activation: 40 kg of hydroxy-terminated polydimethylsiloxane (molecular weight 8000), 15 kg of vinyltriethoxysilane, 0.5 kg of vinylferrocene were added to a high-speed mixer and stirred at 80°C at 800 r / min for 30 min, while 10 kg of nano-silicon dioxide and 0.08 kg of octavinyl octasilsesquioxane were added to complete the premixing and initial dispersion of inorganic particles;

[0051] Crosslinking reaction: 2 kg of di-tert-butyl peroxide was added to the mixed system, the temperature was raised to 110°C, and stirring was maintained at 600 r / min for 2 h to initiate the double bond addition reaction by free radicals to form a network structure, and at the same time to realize the chemical bonding of silane coupling agent and nano-silicon dioxide;

[0052] Product processing: after the reaction system was naturally cooled to room temperature, it was ground to a particle size of ≤5 μm by a three-roll mill to obtain the adhesive.

[0053] Example 2: Preparation method of lightweight high-strength brake disc, comprising the following steps:

[0054] Raw materials and parameters:

[0055] Aluminum alloy A356 (silicon content 7.2 wt%, magnesium content 0.25 wt%): 100 kg;

[0056] Carbon-ceramic composite powder: carbon fiber powder 63 kg (particle size 70 µm), carbon powder 18 kg (particle size 30 µm), silicon carbide powder 13 kg (particle size 3 µm);

[0057] Surface ceramic coating raw material: 95 kg of SiC powder and 5 kg of adhesive;

[0058] Preparation of lightweight inner layer metal matrix (step 1): 100 kg of aluminum alloy A356 was melted and cast, and then aged at 215°C for 4.3 h to obtain an inner layer disc body;

[0059] Surface layer composite coating (step 2): the above carbon-ceramic composite powder was sprayed on the surface of the inner layer disc body by plasma spraying method, the spraying thickness was controlled to be 2.5 mm, the spraying speed was 12 g / min, the spraying distance was 85 mm, the plasma spraying gas was Ar / H2 mixed gas, and the gas flow was 55 L / min;

[0060] Intermediate heat treatment and interface bonding (step 3): under argon protection, annealing at 530°C for 2 h to make the surface layer powder preliminarily sintered and form a metal-ceramic interface bond with the matrix;

[0061] Overall heat treatment (step 4): after quenching to room temperature in oil, the composite whole was tempered at 330°C for 3.5 h to optimize the interface bonding strength and residual stress;

[0062] Machining (Step 5): CNC milling is used to final diameter tolerance ±0.05mm, thickness is machined to 29mm, and flatness is ≤0.02mm. The cooling cutting fluid during machining is a water-based emulsion.

[0063] Surface ceramic coating treatment (step 6): spray a coating consisting of 95kg SiC powder and 5kg binder with a spray thickness of 40µm and cure at 270°C for 1.3h.

[0064] Preparation method of adhesive:

[0065] Raw material mixing and activation: 43 kg of hydroxy-terminated polydimethylsiloxane (molecular weight 9000), 17 kg of vinyltriethoxysilane, and 0.6 kg of vinylferrocene were added to a high-speed mixer and stirred at 850 r / min at 83°C for 33 minutes. At the same time, 12 kg of nano-silica and 0.15 kg of octavinyloctasilsesquioxane were added to complete pre-mixing and preliminary dispersion of inorganic particles.

[0066] Cross-linking reaction: Add 2.3 kg of di-tert-butyl peroxide to the mixed system, raise the temperature to 113 ° C, maintain stirring at 630 r / min for 2.2 hours, and form a network structure through free radical-induced double bond addition reaction, while achieving chemical bonding between the silane coupling agent and nano-silica;

[0067] Product treatment: After the reaction system is naturally cooled to room temperature, it is ground using a three-roll mill to a particle size of ≤5 μm to obtain the binder.

[0068] Example 3: A method for preparing a lightweight and high-strength brake disc, comprising the following steps:

[0069] Raw materials and parameters:

[0070] Aluminum alloy A356 (silicon content 7.3wt%, magnesium content 0.25wt%): 100kg;

[0071] Carbon-ceramic composite powder: 67kg carbon fiber powder (particle size 80µm), 22kg carbon powder (particle size 40µm), 17kg silicon carbide powder (particle size 4µm);

[0072] Surface ceramic coating raw materials: 95kg SiC powder and 5kg binder.

[0073] Preparation of a lightweight inner metal matrix (step 1): 100 kg of aluminum alloy A356 was melted and cast, and then aged at 218°C for 4.7 hours to obtain the inner disk.

[0074] Surface composite material coating (step 2): The carbon-ceramic composite powder is sprayed onto the surface of the inner disk by plasma spraying. The spraying thickness is controlled to 3.5 mm, the spraying speed is 13 g / min, the spraying distance is 90 mm, and the plasma spraying gas is Ar / H2 mixed gas with a gas flow rate of 60 L / min.

[0075] Intermediate heat treatment and interface bonding (step 3): Under argon protection, anneal at 570°C for 2.5 hours to allow the surface powder to be initially sintered and form a metal-ceramic interface bond with the substrate;

[0076] Overall heat treatment (step 4): After quenching the composite in oil to room temperature, it is tempered at 350°C for 4.5 hours to optimize the interface bonding strength and residual stress;

[0077] Machining (Step 5): CNC milling is used to final diameter tolerance ±0.05mm, thickness is machined to 31mm, and flatness is ≤0.02mm. The cooling cutting fluid during machining is a water-based emulsion.

[0078] Surface ceramic coating treatment (step 6): spray a coating consisting of 95kg SiC powder and 5kg binder with a spray thickness of 60µm and cure at 290°C for 1.8h.

[0079] Preparation method of adhesive:

[0080] Raw material mixing and activation: 47 kg of hydroxy-terminated polydimethylsiloxane (molecular weight 9500), 19 kg of vinyltriethoxysilane, and 0.8 kg of vinylferrocene were added to a high-speed mixer and stirred at 950 r / min at 87°C for 38 minutes. At the same time, 14 kg of nano-silica and 0.22 kg of octavinyloctasilsesquioxane were added to complete pre-mixing and preliminary dispersion of the inorganic particles.

[0081] Cross-linking reaction: Add 2.8 kg of di-tert-butyl peroxide to the mixed system, raise the temperature to 118 ° C, maintain stirring at 680 r / min for 2.4 hours, and form a network structure through free radical-induced double bond addition reaction, while achieving chemical bonding between the silane coupling agent and nano-silica;

[0082] Product treatment: After the reaction system is naturally cooled to room temperature, it is ground using a three-roll mill to a particle size of ≤5 μm to obtain the binder.

[0083] Example 4: A method for preparing a lightweight and high-strength brake disc, comprising the following steps:

[0084] Raw materials and parameters:

[0085] Aluminum alloy A356 (silicon content 7.5wt%, magnesium content 0.3wt%): 100kg;

[0086] Carbon-ceramic composite powder: carbon fiber powder 70kg (particle size 100µm), carbon powder 25kg (particle size 50µm), silicon carbide powder 20kg (particle size 5µm);

[0087] Surface ceramic coating raw materials: 95kg Al2O3 powder and 5kg binder.

[0088] Preparation of a lightweight inner metal matrix (step 1): 100 kg of aluminum alloy A356 was melted and cast, and then aged at 220°C for 5 h to obtain the inner disk.

[0089] Surface composite material coating (step 2): The above-mentioned carbon-ceramic composite powder is sprayed on the surface of the inner disk by plasma spraying. The spraying thickness is controlled to 4.0 mm, the spraying speed is 15 g / min, the spraying distance is 100 mm, and the plasma spraying gas is Ar / H2 mixed gas with a gas flow rate of 70 L / min.

[0090] Intermediate heat treatment and interface bonding (step 3): Under nitrogen protection, anneal at 600°C for 3 hours to allow the surface powder to be initially sintered and form a metal-ceramic interface bond with the substrate;

[0091] Overall heat treatment (step 4): After quenching the composite in oil to room temperature, it is tempered at 360°C for 5 hours to optimize the interface bonding strength and residual stress;

[0092] Machining (Step 5): CNC milling is used to achieve a final diameter tolerance of ±0.05mm, a thickness of 32mm, and a flatness of ≤0.02mm. The cooling fluid used during machining is a water-based emulsion.

[0093] Surface ceramic coating treatment (step 6): spray a coating consisting of 95kg Al2O3 powder and 5kg binder with a spray thickness of 70µm and cure at 300℃ for 2h.

[0094] Preparation method of adhesive:

[0095] Raw material mixing and activation: 50 kg of hydroxy-terminated polydimethylsiloxane (molecular weight 10,000), 20 kg of vinyltriethoxysilane, and 0.9 kg of vinylferrocene were added to a high-speed mixer and stirred at 1,000 r / min at 90°C for 40 minutes. At the same time, 15 kg of nano-silica and 0.26 kg of octavinyloctasilsesquioxane were added to complete pre-mixing and preliminary dispersion of the inorganic particles.

[0096] Cross-linking reaction: 3 kg of di-tert-butyl peroxide was added to the mixed system, the temperature was raised to 120°C, and stirring was maintained at 700 r / min for 2.5 hours. A network structure was formed by free radical initiation of double bond addition reaction, and chemical bonding of the silane coupling agent and nano-silica was achieved at the same time;

[0097] Product processing: after the reaction system was naturally cooled to room temperature, it was ground to a particle size of ≤5 μm by a three-roll mill to obtain the adhesive.

[0098] Preparation method of lightweight high-strength brake disc, comprising the following steps:

[0099] Raw materials and parameters:

[0100] Aluminum alloy A356 (silicon content 7.0 wt%, magnesium content 0.2 wt%): 100 kg;

[0101] Carbon ceramic composite powder: carbon fiber powder 60 kg (particle size 50 µm), carbon powder 15 kg (particle size 20 µm), silicon carbide powder 10 kg (particle size 2 µm);

[0102] Surface ceramic coating raw material: 95 kg of Al2O3 powder and 5 kg of adhesive.

[0103] Preparation of lightweight inner metal matrix (step 1): 100 kg of aluminum alloy A356 was melted and cast, and aged at 210°C for 4 h to obtain an inner disc body;

[0104] Surface layer composite material coating (step 2): the above carbon ceramic composite powder was sprayed on the surface of the inner disc body by plasma spraying method, the spraying thickness was controlled to be 2.0 mm, the spraying speed was 10 g / min, the spraying distance was 80 mm, the plasma spraying gas was Ar / H2 mixed gas, and the gas flow was 50 L / min;

[0105] Intermediate heat treatment and interface bonding (step 3): under nitrogen protection, annealing at 500°C for 1.5 h to make the surface layer powder preliminarily sintered and form a metal-ceramic interface bond with the matrix;

[0106] Overall heat treatment (step 4): after quenching to room temperature in oil, tempering at 320°C for 3 h to optimize the interface bonding strength and residual stress;

[0107] Mechanical processing (step 5): numerical control turning and milling to the final diameter tolerance ±0.05 mm, thickness processing to 28 mm, flatness ≤0.02 mm; the cooling cutting fluid during processing is water-based emulsion;

[0108] Surface ceramic coating treatment (step 6): spray a coating composed of 95 kg of Al2O3 powder and 5 kg of binder, with a spray thickness controlled at 30 pm, and cure at 250°C for 1 h.

[0109] Method for preparing the binder:

[0110] Raw material mixing and activation: 40 kg of hydroxy-terminated polydimethylsiloxane (molecular weight 8000), 0.5 kg of vinyl ferrocene were added to a high-speed mixer, stirred at 800 r / min for 30 min at 80°C, while adding 10 kg of nano-silicon dioxide and 0.08 kg of octavinyl octasilsesquioxane, completing the premixing and initial dispersion of inorganic particles;

[0111] Crosslinking reaction: 2 kg of di-tert-butyl peroxide was added to the mixed system, heated to 110°C, and stirred at 600 r / min for 2 hours, and a network structure was formed by free radical initiation of double bond addition reaction, and chemical bonding of silane coupling agent and nano-silicon dioxide was achieved at the same time;

[0112] Product processing: after the reaction system was naturally cooled to room temperature, it was ground to a particle size of ≤5 pm by a three-roll mill to obtain the binder.

[0113] Comparative example 2: method for preparing a lightweight high-strength brake disc, comprising the following steps:

[0114] Raw materials and parameters:

[0115] Aluminum alloy A356 (silicon content 7.0 wt%, magnesium content 0.2 wt%): 100 kg;

[0116] Carbon ceramic composite powder: carbon fiber powder 60 kg (particle size 50 pm), carbon powder 15 kg (particle size 20 pm), silicon carbide powder 10 kg (particle size 2 pm);

[0117] Surface ceramic coating raw material: 95 kg of Al2O3 powder and 5 kg of binder.

[0118] Preparation of lightweight inner metal matrix (step 1): melt and cast 100 kg of aluminum alloy A356, and perform aging treatment at 210°C for 4 h to obtain an inner disc body;

[0119] Surface layer composite material coating (step 2): the above carbon ceramic composite powder is sprayed on the surface of the inner disc body by plasma spraying method, with a spraying thickness controlled at 2.0 mm, a spraying speed of 10 g / min, a spraying distance of 80 mm, and an Ar / H2 mixed gas as the plasma spraying gas with a gas flow of 50 L / min;

[0120] Intermediate heat treatment and interface bonding (step 3): Under nitrogen protection, anneal at 500°C for 1.5 hours to allow the surface powder to be initially sintered and form a metal-ceramic interface bond with the substrate;

[0121] Overall heat treatment (step 4): After quenching the composite in oil to room temperature, it is tempered at 320°C for 3 hours to optimize the interface bonding strength and residual stress;

[0122] Machining (Step 5): CNC milling is used to achieve a final diameter tolerance of ±0.05mm, a thickness of 28mm, and a flatness of ≤0.02mm. The cooling fluid used during machining is a water-based emulsion.

[0123] Surface ceramic coating treatment (step 6): spray a coating consisting of 95kg Al2O3 powder and 5kg binder with a spray thickness of 30µm and cure at 250℃ for 1h.

[0124] Preparation method of adhesive:

[0125] Raw material mixing and activation: 40 kg of hydroxy-terminated polydimethylsiloxane (molecular weight 8000) and 15 kg of vinyltriethoxysilane were added to a high-speed mixer and stirred at 800 r / min for 30 minutes at 80°C. At the same time, 10 kg of nano-silica and 0.08 kg of octavinyloctasilsesquioxane were added to complete the pre-mixing and preliminary dispersion of the inorganic particles.

[0126] Cross-linking reaction: Add 2kg of di-tert-butyl peroxide to the mixed system, raise the temperature to 110°C, maintain stirring at 600r / min for 2 hours, and form a network structure through the double bond addition reaction initiated by free radicals, while achieving chemical bonding between the silane coupling agent and nano-silica;

[0127] Product treatment: After the reaction system is naturally cooled to room temperature, it is ground using a three-roll mill to a particle size of ≤5 μm to obtain the binder.

[0128] Comparative Example 3: A method for preparing a lightweight and high-strength brake disc, comprising the following steps:

[0129] Raw materials and parameters:

[0130] Aluminum alloy A356 (silicon content 7.0wt%, magnesium content 0.2wt%): 100kg;

[0131] Carbon-ceramic composite powder: 60kg carbon fiber powder (particle size 50µm), 15kg carbon powder (particle size 20µm), 10kg silicon carbide powder (particle size 2µm);

[0132] Surface ceramic coating raw materials: 95kg Al2O3 powder and 5kg binder.

[0133] Preparation of a lightweight inner metal matrix (step 1): 100 kg of aluminum alloy A356 was melted and cast, and then aged at 210°C for 4 h to obtain the inner disk.

[0134] Surface composite material coating (step 2): The carbon-ceramic composite powder is sprayed onto the surface of the inner disk by plasma spraying. The spraying thickness is controlled to 2.0 mm, the spraying speed is 10 g / min, the spraying distance is 80 mm, and the plasma spraying gas is Ar / H2 mixed gas with a gas flow rate of 50 L / min.

[0135] Intermediate heat treatment and interface bonding (step 3): Under nitrogen protection, anneal at 500°C for 1.5 hours to allow the surface powder to be initially sintered and form a metal-ceramic interface bond with the substrate;

[0136] Overall heat treatment (step 4): After quenching the composite in oil to room temperature, it is tempered at 320°C for 3 hours to optimize the interface bonding strength and residual stress;

[0137] Machining (Step 5): CNC milling is used to achieve a final diameter tolerance of ±0.05mm, a thickness of 28mm, and a flatness of ≤0.02mm. The cooling fluid used during machining is a water-based emulsion.

[0138] Surface ceramic coating treatment (step 6): spray a coating consisting of 95kg Al2O3 powder and 5kg binder with a spray thickness of 30µm and cure at 250℃ for 1h.

[0139] Preparation method of adhesive:

[0140] Raw material mixing and activation: 40 kg of hydroxy-terminated polydimethylsiloxane (molecular weight 8000), 15 kg of vinyltriethoxysilane, and 0.5 kg of vinylferrocene were added into a high-speed mixer and stirred at 800 rpm for 30 minutes at 80°C. 10 kg of nano-silica was added to complete the pre-mixing and preliminary dispersion of the inorganic particles.

[0141] Cross-linking reaction: Add 2kg of di-tert-butyl peroxide to the mixed system, raise the temperature to 110°C, maintain stirring at 600r / min for 2 hours, and form a network structure through the double bond addition reaction initiated by free radicals, while achieving chemical bonding between the silane coupling agent and nano-silica;

[0142] Product treatment: After the reaction system is naturally cooled to room temperature, it is ground using a three-roll mill to a particle size of ≤5 μm to obtain the binder.

[0143] Test method:

[0144] 1. Static tensile strength test

[0145] Testing instrument: electronic universal testing machine (Instron5569).

[0146] Test conditions: The sample is a rectangular specimen with standard size of 50mm×20mm×5mm.

[0147] Test steps:

[0148] Place the sample in the clamp and stretch it at a constant speed.

[0149] The stretching was carried out at a stretching speed of 10 mm / min until the sample broke.

[0150] Record the maximum tensile force and calculate the static tensile strength (N / mm²).

[0151] Table 1: Static tensile strength test results of brake discs prepared in various embodiments and comparative examples

[0152]

[0153] 2. Thermal fatigue test

[0154] Testing equipment: High temperature fatigue testing machine (MTS831).

[0155] Test conditions:

[0156] Temperature range: room temperature to 800℃.

[0157] Number of cycles: Each cycle lasts 20 seconds, simulating an emergency braking environment.

[0158] Test sample: round brake disc with a diameter of 300 mm and a thickness of 30 mm.

[0159] Test steps:

[0160] The brake disc is subjected to repeated thermal shock tests under 700-800℃ thermal cycle conditions.

[0161] After each cycle, the crack growth is measured (via X-ray imaging or surface crack detection at high temperature).

[0162] The number of cycles to crack initiation was recorded until significant crack growth occurred.

[0163] Table 2: Thermal fatigue test results of brake discs prepared in various embodiments and comparative examples

[0164]

[0165] 3. Heat dissipation performance test

[0166] Test equipment: Thermal infrared imager (FLIR).

[0167] Test conditions:

[0168] Brake system simulation: emergency brake simulation by loading standard vehicle speed (200 km / h).

[0169] Test sample: standard diameter 300 mm brake disc.

[0170] Test procedure:

[0171] Apply braking force using simulated brake system, perform rapid thermal shock test.

[0172] Record the time from 600℃ to 200℃ of the brake disc surface temperature.

[0173] Use infrared imager to collect data and analyze temperature change rate.

[0174] Table 3: Heat dissipation performance test results of brake discs prepared by each example and comparative example

[0175]

[0176] 4. Friction performance and wear resistance test

[0177] Test equipment: friction and wear tester (HT-1000).

[0178] Test conditions:

[0179] Friction disc contacts standard friction plate (ASTM G99 standard).

[0180] Test load: 50N, speed: 1m / s, test time: 20min.

[0181] Test procedure:

[0182] Perform friction test under specified test conditions.

[0183] Measure friction coefficient and record friction disc surface wear depth.

[0184] Table 4: Friction performance and wear resistance test results of brake discs prepared by each example and comparative example

[0185]

[0186] From the above test data, it can be clearly seen that the design of the composite structure of the example significantly improves the static strength, thermal fatigue resistance, heat dissipation efficiency and wear resistance of the brake disc. These technical effects directly come from the optimized combination of lightweight metal matrix and high-strength ceramic surface layer used in the present application.

[0187] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the underlying principles can be applied to other embodiments without departing from the scope of the present application. Accordingly, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a lightweight and high-strength brake disc, characterized in that: The method comprises the following steps, calculated by weight: 1) Preparation of lightweight inner metal matrix: Aluminum alloy A356 is melted and cast in 100 parts and subjected to aging treatment for 4-5 hours to obtain the inner disk body; 2) Surface composite material coating: Prepare carbon-ceramic composite powder, calculated by mass: 60-70 parts of carbon fiber powder, 15-25 parts of carbon powder, and 10-20 parts of silicon carbide powder; The powder is sprayed on the surface of the inner disc body by plasma spraying method, with the spraying thickness controlled at 2.0-4.0mm, the spraying speed at 10-15g / min, and the spraying distance at 80-100mm; 3) Intermediate heat treatment and interface bonding: The coated inner disc is annealed under inert gas protection for 1.5 to 3 hours to allow the surface powder to be initially sintered and form a metal-ceramic interface bond with the substrate; 4) Overall heat treatment: After quenching the composite in oil to room temperature, tempering and holding for 3 to 5 hours to optimize the interface bonding strength and residual stress; 5) Machining: The machine is milled by CNC turning to a final diameter tolerance of ±0.05mm, with a thickness of 28-32mm and a flatness of ≤0.02mm. The cooling cutting fluid during the machining process is a water-based emulsion. 6) Surface ceramic coating treatment: Spraying alumina or silicon carbide ceramic coating, the coating composition is by mass: 95 parts of Al2O3 or SiC powder and 5 parts of binder, the spraying thickness is controlled to be 30-70µm, the curing temperature is 250-300℃, and the heat preservation is 1-2h; The binder is prepared by reacting hydroxy-terminated polydimethylsiloxane, vinyltriethoxysilane, vinylferrocene, nano-silica, octavinyloctasilsesquioxane and di-tert-butyl peroxide; The preparation method of the binder is: Raw material mixing and activation: by weight, add 40-50 parts of hydroxy-terminated polydimethylsiloxane, molecular weight 8000-10000, 15-20 parts of vinyltriethoxysilane, and 0.5-0.9 parts of vinylferrocene into a high-speed mixer, stir at 800-1000 r / min at 80-90°C for 30-40 minutes, and simultaneously add 10-15 parts of nano-silica and 0.08-0.26 parts of octavinyloctasilsesquioxane to complete premixing and preliminary dispersion of inorganic particles; Cross-linking reaction: Add 2-3 parts of di-tert-butyl peroxide to the mixed system, raise the temperature to 110-120°C, maintain stirring at 600-700 r / min for 2-2.5 hours, and form a network structure through the double bond addition reaction initiated by free radicals, while achieving chemical bonding between the silane coupling agent and nano-silica; Product treatment: After the reaction system is naturally cooled to room temperature, it is ground using a three-roll mill to a particle size of ≤5 μm to obtain the binder.

2. The method for preparing a lightweight and high-strength brake disc according to claim 1, characterized in that: The aluminum alloy A356 contains 7.0-7.5 wt % silicon and 0.2-0.3 wt % magnesium.

3. The method for preparing a lightweight and high-strength brake disc according to claim 1, characterized in that: The aging treatment temperature is 210-220°C.

4. The method for preparing a lightweight and high-strength brake disc according to claim 1, characterized in that: The particle size of the carbon fiber powder is 50-100 μm, the particle size of the carbon powder is 20-50 μm, and the particle size of the silicon carbide is 2-5 μm.

5. The method for preparing a lightweight and high-strength brake disc according to claim 1, characterized in that: The plasma spraying gas is composed of Ar / H2 mixed gas, and the gas flow rate is 50-70 L / min.

6. The method for preparing a lightweight and high-strength brake disc according to claim 1, characterized in that: The inert gas is nitrogen or argon.

7. The method for preparing a lightweight and high-strength brake disc according to claim 1, characterized in that: The annealing temperature is 500-600°C.

8. The method for preparing a lightweight and high-strength brake disc according to claim 1, characterized in that: The tempering and holding temperature is 320-360°C.

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