High-carbon brake disc for racing car and preparation method of high-carbon brake disc

Abstract

The invention provides a high-carbon brake disc for a racing car and a preparation method of the high-carbon brake disc, and particularly relates to the technical field of brake discs, the high-carbon brake disc comprises a friction disc and a mounting disc which are coaxially and fixedly connected with each other, the friction disc comprises a first friction ring and a second friction ring which are arranged in parallel, and heat dissipation ribs fixedly arranged between the first friction ring and the second friction ring; a ventilation air duct is formed; the first friction ring, the second friction ring and the radiating ribs are all made of high-carbon microalloyed steel, the mounting disc is made of aluminum alloy, and the high-carbon microalloyed steel contains alloy elements of copper, chromium, molybdenum, nickel and niobium. According to the high-carbon brake disc for the racing car and the preparation method of the high-carbon brake disc, the heat fading resistance, the cracking resistance and the heat dissipation performance of the brake disc under the extreme working condition are improved through the special ventilation hole structure design and the innovative high-carbon composite material formula in cooperation with the specific heat treatment technology.

Description

Technical Field

[0001] This invention belongs to the field of brake disc technology, specifically relating to a high-carbon brake disc for racing cars and its preparation method. Background Technology

[0002] Racing car braking systems need to withstand enormous kinetic energy being converted into heat energy in a very short time, causing the surface temperature of the brake discs to rise sharply, reaching over 800°C, and even instantaneously exceeding 1000°C. Under these extreme conditions, conventional gray cast iron or ordinary alloy steel brake discs are prone to problems such as thermal fade (decreased coefficient of friction), cracking, deformation, and abnormal wear, seriously affecting the braking performance and safety of the racing car.

[0003] While carbon / ceramic composite materials offer high-temperature stability, their extremely high cost and poor braking performance at low temperatures limit their application in certain racing events. Ordinary high-carbon steel and cast iron brake discs, while relatively inexpensive and offering good overall performance, still have room for improvement in material composition, microstructure control, and heat dissipation design.

[0004] Structurally, the traditional symmetrical ventilation hole structure is not optimal in terms of heat dissipation efficiency and stress distribution under high-speed rotation, and is prone to fatigue cracks at stress concentration points; moreover, the brake discs and center drums are mostly molded as one piece, and the whole thing is replaced directly during maintenance and replacement, which is costly.

[0005] Therefore, developing a racing car brake disc that combines excellent high-temperature friction performance, high resistance to thermal cracking, efficient heat dissipation, and controllable cost has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a high-carbon brake disc for racing cars and its preparation method, which solves the technical problem of how to achieve synergistic improvement in the resistance to thermal fading, cracking and heat dissipation performance of brake discs under extreme conditions. Through a special ventilation hole structure design and an innovative high-carbon composite material formula, combined with a specific heat treatment process, the resistance to thermal fading, cracking and heat dissipation performance of brake discs under extreme conditions is improved.

[0007] A high-carbon brake disc for racing cars includes a friction disc and a mounting disc that are coaxially and fixedly connected to each other. The friction disc includes two friction rings, a first friction ring and a second friction ring, arranged in parallel to each other, and heat dissipation fins fixedly disposed between the first friction ring and the second friction ring to form a ventilation duct. The friction ring one, the friction ring two, and the heat dissipation fins are all made of high-carbon microalloy steel, and the mounting plate is made of aluminum alloy. The high-carbon microalloy steel contains alloying elements copper, chromium, molybdenum, nickel, and niobium.

[0008] The chemical composition of the high-carbon microalloyed steel, by weight percentage, includes: C: 3.50%-3.80%, Si: 1.70%-2.30%, Mn: 0.50%-0.90%, S≤0.02%, P≤0.01%, Cr: 0.15%-0.25%, Cu: 0.20%-0.70%, Sn≤0.10%, Ni: 0.50%-1.00%, Al≤0.015%, Nb: 0.10%-0.50%, Mo: 0.50%-1.00%, with the balance being Fe and unavoidable impurities.

[0009] The reason for limiting S and P in this scheme is to avoid the thermal brittleness and cold brittleness of the material.

[0010] A friction layer is fixed on the outer surface of the friction ring one; The friction layer is prepared by composite material based on carbon / silicon carbide ceramic composite material, with graphene as the toughness and thermal conductivity enhancement phase, nano boron nitride as the high-temperature solid lubrication phase, and high carbon microalloyed steel as the intermediate phase.

[0011] The friction layer contains 5-10% graphene, 3-5% nano-boron nitride, and 2-4% high-carbon microalloyed steel.

[0012] It should be noted that the particle size, morphology, and purity of graphene are 3-5 μm, lamellar structure, and at least 99.9%, respectively; the particle size, morphology, and purity of nano boron nitride are 50-100 nm, spherical, and at least 99.9%, respectively; and the average particle size of high carbon microalloy powder is no greater than 0.5 μm.

[0013] The inner side of the heat dissipation rib is provided with multiple notches, and a strip rib is provided between two adjacent heat dissipation ribs. The strip rib is fixed to the inner side of the friction ring one. A dot rib is provided near the end of the heat dissipation rib, and the dot rib is vertically fixed to the inner side of the friction ring one.

[0014] The heat dissipation fins have an Archimedean spiral shape, and their arrangement density is non-uniform along the rotation direction.

[0015] The outer side of the friction ring is provided with a heat dissipation groove.

[0016] The inner surface of the second friction ring is provided with multiple protrusions arranged in a ring array. Each protrusion has a fixing hole, which is fixedly connected to the mounting plate by bolts.

[0017] A method for preparing a high-carbon brake disc for racing cars, specifically including the following steps: Step S1: Vacuum induction melting is performed on high-carbon microalloyed steel, and the corresponding mold is cast to obtain a friction disc; high-temperature melting is performed on aluminum alloy, and the corresponding mold is cast to obtain an installation disc; Step S2: Perform high-temperature homogenization treatment on the mounting plate and friction plate respectively, followed by air cooling; Step S3: Prepare carbon / silicon carbide ceramic composite material, graphene, nano boron nitride powder, and high carbon microalloying powder to prepare the friction layer; Step S4: Graphene, nano boron nitride, and high carbon microalloy powder are uniformly mixed in carbon / silicon carbide ceramic composite material by ultrasonic dispersion, and then hot-pressed to form a porous blank. Among them, the ultrasonic parameters are 60-70MHz, and the hot-pressing parameters are 1790-1910℃ and 25-32MPa.

[0018] Step S5: The porous preform from step S4 is placed in a vacuum furnace and heated and held at a high temperature of approximately 1410-1460°C to ultimately form a densified carbon-ceramic composite material, which forms a friction layer; wherein, the vacuum degree of the vacuum furnace is 10. -1 -10 -3 Pa.

[0019] The role of graphene: bridging and preventing crack propagation like "steel bars," significantly improving toughness and thermal conductivity. The role of nano-boron nitride: providing lubrication at extreme high temperatures, stabilizing the coefficient of friction, and preventing seizing. The main purpose of hot pressing in step S4 is shaping and pre-densification, while the vacuum heating in step S5 is to complete the sintering reaction or eliminate internal stress.

[0020] Step S6: The friction layer prepared in step S5 is precisely joined with the outer side of the friction ring and placed in a vacuum hot press furnace. Under high temperature, high pressure and extremely high vacuum conditions, it is held for time t to achieve metallurgical bonding between the friction layer and the friction ring. Among them, the high temperature, high pressure and vacuum degree of the vacuum hot press are 1560-1750℃, 28-34MPa, and 10, respectively. -1 -10 - 2 Pa, holding time t = 0.5-1.5h.

[0021] At the interface, elements such as Fe and Cr in the steel will interdiffuse with SiC and C in the carbon ceramic, forming a gradient interface layer with gradually changing composition, thereby achieving atomic-level metallurgical bonding with extremely high bonding strength.

[0022] Step S7: Securely connect the mounting plate to the friction plate.

[0023] More preferably, the brake disc blank is turned and ground to produce the asymmetric vortex-shaped ventilation holes and gradient depth heat dissipation grooves.

[0024] Ideally, the brake disc is shot-peened to introduce compressive stress on the surface, further improving fatigue resistance, and finally dynamic balancing is performed.

[0025] More preferably, the carbon / silicon carbide ceramic composite material in this scheme can be any one of pressureless sintered silicon carbide ceramics, core-shell structured SiC@Ti(C,N) composite materials, or solid-state sintered SiC / B4C composite ceramics. Pressureless sintered silicon carbide ceramics are also a type of composite material.

[0026] Technical features not described in detail in this solution, such as related operations, parameter selection, processing procedures, metallographic grinding, and material type selection, can be understood and implemented by those skilled in the art and will not be elaborated here.

[0027] The beneficial effects of this invention are as follows: (1) This project uses high carbon content gray cast iron. On the basis of the carbon content of ordinary gray cast iron brake disc not exceeding 3.4%, the carbon content is increased to 3.50%-3.80%. Carbon in gray cast iron mainly exists in the form of graphite. Graphite has almost no strength, which gives gray cast iron a strong vibration damping ability. At the same time, it has a large thermal conductivity and strong heat storage capacity, which can quickly transfer the heat generated by braking friction, keep the brake disc at a low temperature, and stabilize its performance. By rationally selecting alloying elements such as copper, chromium, molybdenum, nickel, and niobium, the content of pearlite in the matrix was ensured, the pearlite was strengthened, and the graphite length was optimized. Under the condition of high carbon content (high graphite volume fraction), higher mechanical properties and machinability were obtained, while the thermal conductivity, wear resistance and thermal fatigue resistance of the material were significantly improved. (2) The air duct is designed with heat dissipation fins to increase the contact area between the race car brake disc and the air. When the race car is in motion, the air quickly passes through the air duct to remove heat, stabilize the airflow, optimize heat dissipation performance, improve thermal stability, and improve braking stability. The function of the strip ribs is to prevent the brakes from cracking or developing cracks during extreme braking. The purpose of dotted ribs is twofold: first, to prevent excessive unribbed areas from causing extreme braking during development; and second, to ensure core strength, making the production process feasible. (3) Material advantages: Through the optimized high carbon microalloying composition, especially the synergistic effect of Mo, Ni, etc., the material can still maintain high hardness, high strength and stable friction coefficient at high temperature. Its high temperature (700℃) tensile strength is more than 20% higher than that of conventional high carbon steel (high carbon microalloying steel without alloying elements). The high carbon content ensures that the brake disc has high hardness and high wear resistance. The composite addition of molybdenum and nickel forms stable carbides with carbon, which significantly improves the material's high temperature strength, resistance to tempering softening and resistance to thermal fatigue. (4) The friction layer contains carbon / silicon carbide ceramic composite material, graphene, nano boron nitride powder, and high carbon microalloy powder, achieving the following technical effects: First, there is no thermal degradation braking: the carbon ceramic friction layer remains stable above 1000°C, which fundamentally eliminates thermal degradation. Second, it has ultra-high wear resistance: SiC ceramic matrix + nano boron nitride reinforcing phase, resulting in extremely low wear rate; Thirdly, it has excellent thermal shock resistance: the high thermal conductivity of graphene and steel substrate prevents heat from accumulating on the surface and quickly disperses it to the interior, avoiding surface cracking. Fourth, high mechanical strength and toughness: The steel matrix provides back support, avoiding the brittleness of pure ceramic materials, and can withstand intense vibration and impact; Fifth, a stable coefficient of friction: nano-boron nitride provides lubrication over a wide temperature range, ensuring smooth braking. Attached Figure Description

[0028] Figure 1 This is a three-dimensional structural diagram of the brake disc in this invention.

[0029] Figure 2 This is a schematic diagram of the external structure of the friction disc in this invention.

[0030] Figure 3 This is a schematic diagram of the internal structure of the friction disc in this invention.

[0031] Figure 4 This is a test diagram of the interface structure between the friction ring and the friction layer in this invention.

[0032] The reference numerals in the attached drawings are as follows: 1. Friction ring II; 11. Protrusion; 2. Heat dissipation rib; 21. Notch; 22. Dotted rib; 3. Strip rib; 4. Friction ring I; 5. Friction layer; 51. Interface layer; 6. Mounting plate; 7. Mounting hole. Detailed Implementation

[0033] To more clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution. Example

[0034] See Figures 1-3 A high-carbon brake disc for racing cars includes a friction disc and a mounting disc 6 that are coaxially and fixedly connected to each other. The friction disc includes two friction rings 4 and 1 arranged in parallel to each other, and a heat dissipation fin 2 fixedly disposed between the friction rings 4 and 1 to form a ventilation duct. Friction ring 1, friction ring 2, and heat dissipation fin 2 are all made of high-carbon microalloy steel, while mounting plate 6 is made of aluminum alloy. The high-carbon microalloy steel contains alloying elements such as copper, chromium, molybdenum, nickel, and niobium.

[0035] The chemical composition of high-carbon microalloyed steel, by weight percentage, includes: C: 3.50%-3.80%, Si: 1.70%-2.30%, Mn: 0.50%-0.90%, S≤0.02%, P≤0.01%, Cr: 0.15%-0.25%, Cu: 0.20%-0.70%, Sn≤0.10%, Ni: 0.50%-1.00%, Al≤0.015%, Nb: 0.10%-0.50%, Mo: 0.50%-1.00%, with the balance being Fe and unavoidable impurities.

[0036] It should be noted that the chemical composition of the high-carbon microalloyed steel in Example 1, by weight percentage, includes: C: 3.58%, Si: 1.91%, Mn: 0.65%, S≤0.02%, P≤0.01%, Cr: 0.21%, Cu: 0.55%, Sn≤0.10%, Ni: 0.81%, Al≤0.015%, Nb: 0.25%, Mo: 0.70%, with the balance being Fe and unavoidable impurities. The following experimental group was designed: Test Group A: Friction Ring 4 is made entirely of high-carbon microalloyed steel, with a carbon content of 3.58%. Test Group B: Friction Ring 4 is made entirely of high-carbon microalloyed steel, with a carbon content of 3.8%. The carbon content differed between experimental group A and experimental group B, while the other components were the same. Comparison Group 1: Friction Ring 4 is made entirely of ordinary high-carbon steel brake disc (high-carbon micro-alloy steel with alloy components removed), which is commonly used in existing ordinary brake discs; Comparative Group 2: Friction Ring 4 is entirely made of carbon / ceramic composite material. Carbon / ceramic composite material is a new type of composite material with carbon fiber as reinforcement and silicon carbide as continuous matrix. Table 1 shows the brake disc performance test results of the experimental group, comparative group 1, and comparative group 2 in Example 1. Material properties were tested at room temperature.

[0037] Table 1 shows the brake disc performance test results for the experimental group, control group 1, and control group 2 in Example 1 of this embodiment. test hardness coefficient of thermal expansion Surface emissivity Tensile strength (MPa) Experimental group A 214HBW (Britton hardness) <![CDATA[9.1×10 -6 / K]]> 0.82 289.5 Experimental group B 232HBW (Britton hardness) <![CDATA[8.4×10 -6 / K]]> 0.84 305.5 Comparison Group 1 189HBW (Britton hardness) <![CDATA[8.4×10 -6 / K]]> 0.80 268.4 Comparison Group 2 29 GPa (Vickers hardness HV) <![CDATA[3.2×10 -6 / K]]> 0.85 272.8 As can be seen from Table 1, the hardness, coefficient of thermal expansion, and tensile strength of this experimental group are all superior in terms of technical performance. The surface emissivity is comparable to existing technologies, and it also has good heat dissipation. Although the hardness value is lower than that of the control group 2, its tensile strength is greater than that of the control groups 1 and 2, indicating that the crack resistance of the experimental group is better. Comparing experimental groups A and B, it can be concluded that when the carbon content increases, the hardness, coefficient of thermal expansion, surface emissivity, and tensile strength are all optimized. In particular, the increase in carbon content helps to form more graphite, thereby reducing the coefficient of thermal expansion of the material, which further enhances the material's resistance to thermal cracking.

[0038] According to the conversion relationship between Brinell hardness and Vickers hardness, 214HBW (Brown hardness) is converted to Vickers hardness of 203.3HV.

[0039] All carbon / ceramic composite materials involved in the embodiments are 2D-C / SiC composite materials, prepared by pressureless sintering, with a carbon content of 3wt%. Example

[0040] Based on Example 1, Example 2 is presented here.

[0041] See Figures 1-3 A friction layer 5 is fixed on the outer surface of the friction ring 4; The friction layer 5 is prepared by composite material based on carbon / silicon carbide ceramic composite material, with graphene as the toughness and thermal conductivity enhancement phase, nano boron nitride as the high temperature solid lubrication phase, and high carbon microalloyed steel as the intermediate phase.

[0042] In friction layer 5, the graphene content is 5-10%, the nano boron nitride content is 3-5%, and the high carbon microalloy steel content is 2-4%.

[0043] The graphene has a particle size of 3-5 μm, a layered structure, and a purity of at least 99.9%, respectively; the boron nitride nanoparticles have a particle size of 50-100 nm, a spherical shape, and a purity of at least 99.9%, respectively; and the high-carbon microalloy powder has an average particle size of no more than 0.5 μm.

[0044] Multiple notches 21 are provided on the inner side of the heat dissipation rib 2. A strip rib 3 is provided between two adjacent heat dissipation ribs 2. The strip rib 3 is fixed on the inner side of the friction ring 4. A dot rib 22 is provided near the end of the heat dissipation rib 2. The dot rib 22 is vertically fixed on the inner side of the friction ring 4.

[0045] The profile of heat dissipation fin 2 is an Archimedean spiral, and its arrangement density is non-uniform along the rotation direction.

[0046] The outer surface of friction ring 4 is provided with heat dissipation grooves.

[0047] The inner side of the friction ring 1 has multiple protrusions 11 arranged in a ring array. Each protrusion 11 has a fixing hole, which is fixedly connected to the mounting plate 6 by bolts. The outer end of the mounting plate 6 has a mounting hole 7, which is fixed to the center of the vehicle's suspension system by mounting bolts.

[0048] The following test group was designed in this embodiment 1 to verify the heat fade resistance, crack resistance and heat dissipation performance of the prepared high carbon brake disc under extreme working conditions.

[0049] Experimental Group 1: By mass fraction, the friction layer 5 contains 5% graphene, 3% nano boron nitride, and 4% high-carbon microalloyed steel.

[0050] Experimental Group 2: By mass fraction, the friction layer 5 contains 7% graphene, 4% nano boron nitride, and 3% high-carbon microalloyed steel.

[0051] Experimental Group 3: By mass fraction, the friction layer 5 contains 10% graphene, 5% nano boron nitride, and 2% high-carbon microalloyed steel.

[0052] Hardness was tested using a hardness tester to investigate resistance to thermal degradation; the coefficient of thermal expansion was tested using thermomechanical analysis (TMA) to investigate crack resistance; and the surface emissivity was measured using a radiometer to investigate heat dissipation performance. Table 2 shows the performance test results for each experimental group.

[0053] Table 2 Performance test table of each test group in Example 2 of this embodiment test hardness coefficient of thermal expansion Surface emissivity Tensile strength (MPa) Interfacial shear strength (MPa) Experimental group 1 45 GPa (Vickers hardness HV) <![CDATA[2.7×10 -6 / K]]> 0.84 305.2 291 Experimental group 2 47 GPa (Vickers hardness HV) <![CDATA[2.3×10 -6 / K]]> 0.89 312.6 302 Experimental group 3 51 GPa (Vickers hardness, HV) <![CDATA[1.9×10 -6 / K]]> 0.93 320.4 318 Comparing Table 1 and Table 2, it can be seen that the friction layer 5 prepared in this scheme has a much higher hardness at room temperature than ordinary high carbon steel and carbon / ceramic composite materials. Moreover, the hardness increases with the increase of graphene and nano boron nitride. The coefficient of thermal expansion in test groups 1-3 is also smaller than that of the prior art, indicating stronger crack resistance. The surface emissivity is higher than that of the prior art, indicating that it is easier to dissipate heat.

[0054] Therefore, the brake disc prepared in this scheme achieves a synergistic improvement in its resistance to thermal fading, cracking, and heat dissipation under extreme working conditions.

[0055] See Figure 4 The thickness of the diffused interface layer 51 was found to be 2-3 μm after testing. Its shear strength test results are shown in Table 2. The interface shear strength is comparable to the tensile strength and has a very high value. No further component testing was conducted in this scheme, so only an interface schematic diagram is provided. However, it can be seen from the diagram that there is obvious layering, indicating obvious atomic diffusion. The interface layer 51 also exhibits a gradient visual effect, proving that the components designed in this scheme are reasonable.

[0056] It should be noted that the data in Tables 1 and 2 are average values ​​obtained from multiple tests using this method, and can basically reflect the comprehensive mechanical properties of the prepared brake disc. The test data in each embodiment will be affected by various factors such as the type of material selected, internal structure, preparation process, and test direction. However, these are all data obtained under conventional operations based on existing technology. Different operations may result in deviations, but overall, they have little impact on the experimental conclusions and can basically confirm the experimental results.

[0057] The performance tests (such as hardness and coefficient of thermal expansion) in Examples 1 and 2 are based on ASTM standards. Racing brake discs can operate at temperatures between 300-800°C. However, since high-temperature testing is not practically convenient, this method uses room temperature for testing. The results can indirectly indicate the performance at high temperatures. This is hereby stated.

[0058] Specifically, although some performance tests were conducted at room temperature, these data are sufficient to indirectly and reasonably demonstrate the superior performance of the brake disc of this invention at high temperatures. The reason is as follows: Resistance to thermal degradation and high hardness: The extremely high Vickers hardness (45-51 GPa) exhibited by the friction layer at room temperature stems from its robust SiC ceramic matrix and graphene reinforcement network. This strong atomic bonding and toughening mechanism, present even at room temperature, is the structural basis for its resistance to softening and maintenance of the coefficient of friction at high temperatures.

[0059] Crack resistance and low thermal expansion: The friction layer has an extremely low coefficient of thermal expansion (1.9-2.7×10⁻⁻⁻⁴). 6 The / K) indicates that its volume change is minimal when heated, which inherently determines its excellent resistance to thermal shock and thermal fatigue, and can effectively suppress the generation and propagation of high-temperature cracks.

[0060] Interface reliability: The high interface bonding strength exhibited by the friction layer and the steel backing at room temperature proves the success of the metallurgical bonding. This strong interface is the key guarantee for withstanding the huge shear stress caused by the difference in thermal expansion at high temperatures.

[0061] Intrinsic high-temperature resistance of the material design: The nano boron nitride (high-temperature lubricating phase), high-melting-point SiC matrix, and stable carbides formed by Mo, Nb, etc. in steel, which are actively introduced in this invention, are all recognized high-temperature stable phases. Their existence at room temperature is a prerequisite for them to perform high-temperature functions.

[0062] In summary, the superior overall performance exhibited by this invention at room temperature is a direct reflection of its microstructure and material design. This structure and design determine that it will inevitably possess the ability to resist thermal degradation, cracking, and efficient heat dissipation under high-temperature conditions. Example

[0063] This embodiment is one of the preferred solutions, and its specific parameters are as follows, all of which fall within the scope defined by claim 10.

[0064] A method for preparing a high-carbon brake disc for racing cars, specifically including the following steps: Step S1: Vacuum induction melting is performed on high-carbon microalloyed steel, and the corresponding mold is poured to obtain a friction disc; high-temperature melting is performed on aluminum alloy, and the corresponding mold is poured to obtain an mounting disc 6; Step S2: Perform high-temperature homogenization treatment on mounting plate 6 and friction plate, followed by air cooling; It should be noted that in step S2, the homogenization temperature of the friction disc is 610-720℃, the holding time is 0.5-1.0h, and it is cooled in the furnace at 350℃ and then air-cooled; the homogenization temperature of the mounting disc 6 is 420-530℃, the holding time is 1.5-2.5h, and it is cooled in the furnace at 200℃ and then air-cooled; the minimum value of the range is selected in this embodiment 3.

[0065] Step S3: Prepare carbon / silicon carbide ceramic composite material, graphene, nano boron nitride powder, and high carbon microalloy powder to prepare friction layer 5; Step S4: Graphene, nano boron nitride, and high carbon microalloy powder are uniformly mixed in carbon / silicon carbide ceramic composite material by ultrasonic dispersion, and then hot-pressed to form a porous blank. Among them, the ultrasonic parameters are 60MHz and the hot-pressing parameters are 1890℃ and 25MPa.

[0066] Step S5: Place the porous blank from step S4 in a vacuum furnace and heat and hold it at a high temperature of about 1410-1460°C to finally form a densified carbon ceramic composite material, forming the friction layer 5. The vacuum degree of the vacuum furnace is 10. -2 Pa.

[0067] The role of graphene: to bridge and prevent crack propagation like "steel bars", greatly improving toughness and heat conduction path; the role of nano-boron nitride: to provide lubrication at extreme high temperatures, stabilize the coefficient of friction, and prevent seizing.

[0068] Step S6: The friction layer 5 and the outer side of the friction ring 4 prepared in step S5 are precisely joined together and placed in a vacuum hot press furnace. Under the conditions of high temperature, high pressure and extremely high vacuum, the mixture is held for time t to achieve metallurgical bonding between the friction layer 5 and the friction ring 4. The vacuum hot press furnace has a high temperature of 1560℃, a high pressure of 28MPa, and a vacuum degree of 10 MPa. -2 Pa, held for t=1h.

[0069] At the interface, elements such as Fe and Cr in the steel will interdiffuse with SiC and C in the carbon ceramic, forming a gradient interface layer with gradually changing composition, thereby achieving atomic-level metallurgical bonding with extremely high bonding strength.

[0070] Step S7: Securely connect the mounting plate 6 to the friction plate.

[0071] Even better, the brake disc blank is machined by turning and grinding, and the resulting asymmetric vortex-shaped ventilation holes and gradient depth heat dissipation grooves are machined.

[0072] Ideally, the brake disc is shot-peened to introduce compressive stress on the surface, further improving fatigue resistance, and finally dynamic balancing is performed.

[0073] The technical features of this invention not described can be implemented by or using existing technology, and will not be repeated here. Of course, the above description is not a limitation of this invention, and this invention is not limited to the examples above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention should also be within the protection scope of this invention.

Claims

1. A high-carbon brake disc for racing cars, comprising a friction disc and a mounting disc (6) fixed coaxially to each other, characterized in that, The friction disc comprises two friction rings (4) and (1) arranged in parallel, a heat dissipation rib (2) fixed between the friction ring (1) and the friction ring (2), and a ventilation air duct is formed. The material of the friction ring (4), the friction ring (1) and the heat dissipation rib (2) is high-carbon micro-alloy steel, and the mounting disc (6) is made of aluminum alloy.

2. The high carbon brake disc for racing cars according to claim 1, characterized in that, The high-carbon micro-alloy steel contains alloying elements of copper, chromium, molybdenum, nickel and niobium. The chemical composition of the high-carbon micro-alloy steel includes, by weight percentage:

3. The high carbon brake disc for racing cars according to claim 2, characterized in that, C: 3.50%-3.80%, Si: 1.70%-2.30%, Mn: 0.50%-0.90%, S≤0.02%, P≤0.01%, Cr: 0.15%-0.25%, Cu: 0.20%-0.70%, Sn≤0.10%, Ni: 0.50%-1.00%, Al≤0.015%, Nb: 0.10%-0.50%, Mo: 0.50%-1.00%, and the balance is Fe and unavoidable impurities. The outer side of the friction ring (4) is fixed with a friction layer (5); 4. The high carbon brake disc for racing cars according to claim 3, characterized in that, The friction layer (5) is prepared by using carbon / silicon carbide ceramic composite material as the base, graphene as the toughness and heat conduction enhancement phase, nano boron nitride as the high-temperature solid lubrication phase, and high-carbon micro-alloy steel as the intermediate phase. The content of graphene in the friction layer (5) is 5-10% by mass fraction, the content of nano boron nitride is 3-5%, and the content of high-carbon micro-alloy steel is 2-4%.

5. The high carbon brake disc for racing cars according to claim 3, characterized in that, The particle size, morphology and purity of graphene are 3-5 μm, lamellar structure and at least 99.9%, respectively; the particle size, morphology and purity of nano boron nitride are 50-100 nm, spherical and at least 99.9%, respectively; and the average particle size of high-carbon micro-alloy powder is not greater than 0.5 μm.

6. The high carbon brake disc for racing cars according to claim 1, characterized in that, The carbon / silicon carbide ceramic composite material is any one of pressureless sintered silicon carbide ceramic, core-shell structure SiC@Ti(C,N) composite material, and solid-phase sintered SiC / B4C composite ceramic.

7. The high carbon brake disc for racing cars according to claim 6, characterized in that, The inner side of the heat dissipation rib (2) is provided with a plurality of openings (21), and a strip-shaped rib (3) is arranged between adjacent two heat dissipation ribs (2), the strip-shaped rib (3) is fixed to the inner side of the friction ring (4), a point-shaped rib (22) is arranged near the end of the heat dissipation rib (2), and the point-shaped rib (22) is fixed vertically to the inner side of the friction ring (4).

8. The high carbon brake disc for racing cars according to claim 1, characterized in that, The profile of the heat dissipation rib (2) is an Archimedes spiral, and the arrangement density thereof is non-uniform along the rotation direction.

9. The high carbon brake disc for racing cars according to claim 1, characterized in that, The outer side of the friction ring (4) is provided with a heat dissipation groove.

10. A method for producing a high carbon racing brake disc for a racing car, for producing a high carbon racing brake disc according to any one of claims 1 to 9, characterized in that The inner side of the friction ring (2) is provided with a plurality of convex portions (11) in an annular array, the convex portions (11) are provided with fixing holes, and the fixing holes are fixedly connected with the mounting disc (6) through bolts. Specifically comprising the following steps: Step S1: vacuum induction melting of high-carbon micro-alloy steel, pouring into a corresponding mold to obtain a friction disc; high-temperature melting of aluminum alloy, pouring into a corresponding mold to obtain a mounting disc (6); Step S2: high temperature homogenization treatment is performed on the mounting disc (6) and the friction disc respectively, and air cooling is performed; Step S3: carbon / silicon carbide ceramic composite material, graphene, nano boron nitride powder, and high-carbon micro alloy powder are prepared to prepare the friction layer (5); Step S4: the graphene, nano boron nitride, and high-carbon micro alloy powder are uniformly mixed in the carbon / silicon carbide ceramic composite material through ultrasonic dispersion, and then hot pressing is performed to form a porous blank; Step S5: the porous blank in step S4 is placed in a vacuum furnace and heated at a high temperature of about 1410-1460°C for a certain time, so as to finally form a densified carbon ceramic composite material and form the friction layer (5); Step S6: the friction layer (5) prepared in step S5 and the outer side of the friction ring one (4) are precisely butt-jointed, and then placed in a vacuum hot pressing furnace, so as to realize metallurgical bonding between the friction layer (5) and the friction ring one (4) under the conditions of high temperature, high pressure, and extremely high vacuum degree for a time t; Step S7: the mounting disc (6) is fixedly connected with the friction disc.

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