Carbon ceramic brake discs and their preparation methods, braking systems and vehicles

Abstract

This application provides a carbon-ceramic brake disc, its manufacturing method, a braking system, and a vehicle. Due to its special structure, this carbon-ceramic brake disc is not prone to cracking during use and has a high coefficient of metal friction, thus offering both a long service life and high reliability.

Description

Technical Field

[0001] This application relates to the field of brake material technology, specifically to carbon ceramic brake discs and their preparation methods, braking systems, and vehicles. Background Technology

[0002] Currently, carbon-ceramic brake discs are gaining attention due to their advantages such as low density, high strength, and high hardness. However, carbon-ceramic brake discs are generally obtained by directly infiltrating carbon fiber / carbon porous bodies through a silicon infiltration reaction. Carbon-ceramic brake discs made in this way are prone to cracking after repeated braking, leading to brake disc failure and severely limiting the service life and reliability of the brake discs.

[0003] Furthermore, when brake discs are used in braking systems, the friction pads in the braking system clamp the two surfaces of the brake disc to stop its rotation. Generally, these friction pads are composed of metal. However, the aforementioned carbon-ceramic brake discs have a limited coefficient of friction with metal, resulting in significant damage to the metal friction pads during high-speed braking. This is detrimental to both the service life of the braking system and its braking performance. Therefore, there is an urgent need to provide a carbon-ceramic brake disc with a special structural design to improve its metal friction coefficient and extend its service life. Summary of the Invention

[0004] In view of this, this application provides a carbon ceramic brake disc. Due to its special structure, the carbon ceramic brake disc is not easy to crack during use and has a high metal friction coefficient, thus having both a long service life and high reliability.

[0005] The first aspect of this application provides a carbon ceramic brake disc, including a bearing layer and friction layers disposed on opposite sides of the bearing layer; the friction layer includes a transition layer and a functional layer stacked together, the transition layer being close to the bearing layer;

[0006] The carrier layer is a carbon / silicon carbide composite material; the transition layer includes a silicon carbide / carbon composite material, and the volume percentage of silicon carbide in the transition layer is greater than the volume percentage of silicon carbide in the carrier layer; the functional layer includes a silicon carbide / carbon / metal composite material, wherein the metal is a metal that can form a solid solution with carbon.

[0007] The friction layer of the aforementioned carbon-ceramic brake disc contains both a functional layer and a transition layer. The functional layer has good wear resistance and a high metal friction coefficient. Meanwhile, the transition layer can reduce the compositional difference between the functional layer and the load-bearing layer, thereby reducing the cracking caused by excessive stress on the brake disc during braking, thus extending the service life of the brake disc and improving its reliability.

[0008] Optionally, the volume ratio of silicon carbide to carbon in the functional layer is greater than the volume ratio of silicon carbide to carbon in the transition layer.

[0009] Optionally, the friction layer comprises n stacked unit layers, wherein the n unit layers include a unit layers constituting the transition layer and b unit layers constituting the functional layer; n is a positive integer greater than or equal to 2, a and b are each independently positive integers, and a + b = n;

[0010] I i+1 >I i Among them, I i The volume of silicon carbide in the i-th unit layer is the proportion of the sum of the volumes of silicon carbide and carbon; wherein the i-th unit layer is any layer from the 1st unit layer to the (n-1)th unit layer, and the 1st unit layer is located close to the carrier layer, 1≤i≤n-1, and i is a positive integer.

[0011] Optionally, 5% ≤ I i+1 -I i ≤20%.

[0012] Optionally, the thickness of each unit layer is independently within the range of 0.4 mm to 1.0 mm.

[0013] Optionally, the thickness of the friction layer is 3.0 mm to 6.0 mm.

[0014] Optionally, the thickness of the transition layer is 2.0 mm to 5.0 mm; the thickness of the functional layer is 1.0 mm to 3.0 mm; and the thickness of the bearing layer is 30.0 mm to 50.0 mm.

[0015] Optionally, the metal is dispersed in the functional layer in the form of powder, and the D50 particle size of the powder is in the range of 0.5 μm to 20 μm.

[0016] The second aspect of this application provides a method for preparing a carbon ceramic brake disc, comprising the following steps:

[0017] (1) A carbon fiber preform is provided, the carbon fiber preform comprising carbon fibers impregnated with a first slurry containing carbon powder; at least one unit layer preform is formed on opposite sides of the carbon fiber preform to bond the unit layer preform to the carbon fiber preform; wherein the unit layer preform comprises carbon fiber cloth; during the formation process, a second slurry is injected into the unit layer preform; the second slurry comprises carbon powder and silicon carbide powder to obtain a first preform;

[0018] (2) At least one unit layer preform is formed on each of the opposite sides of the first preform; wherein, during the formation process, a second slurry containing metal powder is injected into the unit layer preform to obtain a second preform; the metal powder is a metal powder that can form a solid solution with carbon.

[0019] (3) After carbonizing the second preform, chemical vapor deposition carbon treatment is performed, followed by high-temperature heat treatment and silicon infiltration treatment, so that the carbon fiber preform is transformed into a carbon / silicon carbide composite material support layer, the unit layer preform injected with the second slurry is transformed into a transition layer, and the unit layer preform injected with the second slurry containing metal powder is transformed into a functional layer, thereby obtaining a carbon ceramic brake disc; wherein, the transition layer includes silicon carbide / carbon composite material, and the volume percentage of silicon carbide in the transition layer is greater than the volume percentage of silicon carbide in the support layer; the functional layer includes silicon carbide / carbon / metal composite material.

[0020] The above preparation method has simple steps, high process reliability, and high production efficiency, and can realize large-scale industrial production.

[0021] Optionally, the volume ratio of silicon carbide powder to carbon powder in the second slurry used to form the transition layer and the functional layer increases layer by layer with the stacking direction of the unit layer preform.

[0022] Optionally, the volume ratio of silicon carbide powder to carbon powder in the second slurry used to form the transition layer and the functional layer increases layer by layer from 1:(4-9) to 10:0.

[0023] Optionally, the volume percentage of iron powder is 15% to 30% based on the dry matter in the second slurry containing added iron.

[0024] A third aspect of this application provides a braking system, including the carbon-ceramic brake disc provided in the first aspect of this application, or a carbon-ceramic brake disc obtained by the preparation method described in the second aspect of this application. Due to the use of the carbon-ceramic brake disc provided in this application, the braking system has better braking performance, higher reliability, and a longer service life.

[0025] Optionally, the braking system includes the carbon-ceramic brake disc, brake caliper bracket, brake caliper housing, and friction pads.

[0026] The fourth aspect of this application provides a vehicle that includes the braking system provided in the third aspect of this application. Because it incorporates the braking system provided in the third aspect of this application, the vehicle has good market competitiveness.

[0027] Optionally, the means of transport includes a vehicle or an aircraft; wherein the vehicle includes at least one of an automobile and a rail transit train. Attached Figure Description

[0028] Figure 1 A simplified schematic diagram of a modified carbon-ceramic brake disc provided in this application;

[0029] Figure 2 A simplified schematic diagram illustrating another variation of the carbon-ceramic brake disc provided in this application.

[0030] Labeling explanation: 100-Carbon ceramic brake disc; 10-Bearing layer; 20-Friction layer; 21-Transition layer; 22-Functional layer; 30-Unit layer. Detailed Implementation

[0031] Please see Figure 1 This application provides a carbon ceramic brake disc 100, which includes a bearing layer 10 and friction layers 20 disposed on opposite sides of the bearing layer 10; the friction layer 20 includes a transition layer 21 and a functional layer 22 stacked together, with the transition layer 21 disposed close to the bearing layer 10;

[0032] The carrier layer 10 comprises a carbon / silicon carbide material; the transition layer 21 comprises a silicon carbide / carbon composite material, and the volume percentage of silicon carbide in the transition layer 21 is greater than the volume percentage of silicon carbide in the carrier layer; the functional layer 22 comprises a silicon carbide / carbon / metal composite material; wherein the metal is a metal that can form a solid solution with carbon.

[0033] The load-bearing layer in the aforementioned carbon-ceramic brake disc provides sufficient toughness and mechanical support, while the carbon fiber in the functional layer provides a certain degree of toughness, and silicon carbide provides hardness and wear resistance. Specifically, when braking occurs, the friction pads in the braking system clamp the carbon-ceramic brake disc, and the metal in the friction pads directly contacts the functional layer of the carbon-ceramic brake disc. At this time, the metal in the functional layer can generate adhesive friction with the metal material on the friction pads, thereby increasing the coefficient of friction between the functional layer and the friction pads without significantly increasing the density of the carbon-ceramic brake disc. This improves the braking performance of the final brake disc and enhances the reliability of the entire braking system, particularly reducing friction pad wear during high-speed braking, thus extending the service life of the entire braking system. Simultaneously, the presence of the transition layer reduces the compositional difference between the functional layer and the load-bearing layer, thereby reducing cracking of the final brake disc due to excessive stress during braking, further extending the service life of the final brake disc and improving its reliability.

[0034] Furthermore, the presence of metal enhances the thermal conductivity of the functional layer, allowing heat generated after braking to dissipate rapidly within it, reducing heat concentration and thus further ensuring the reliability of the final brake disc and extending its service life. Additionally, based on the property that metals can form solid solutions with carbon, the dissolution of carbon into the metal lattice can appropriately increase the hardness and strength of the metal, benefiting the performance of the carbon-ceramic brake disc. With the synergy of the aforementioned load-bearing layer, transition layer, and functional layer, this carbon-ceramic brake disc achieves both a long service life and high reliability.

[0035] Specifically, in this embodiment, the supporting layer 10 comprises a carbon fiber reinforced carbon / silicon carbide composite material, wherein carbon fibers are distributed as a reinforcing phase in the continuous phase of carbon material (e.g., deposited carbon) / silicon carbide. The transition layer 21 comprises a carbon fiber reinforced silicon carbide / carbon composite material, specifically, a mixture of silicon carbide and carbon material serves as the continuous phase, in which carbon fibers are distributed as reinforcement. The functional layer 22 comprises a carbon fiber reinforced silicon carbide / carbon / metal composite material, specifically, the functional layer 22 comprises a continuous phase comprising a mixture of carbon material and metal, and silicon carbide material, in which carbon fibers are distributed as reinforcement. The mixture of carbon material and metal in the continuous phase of the functional layer may include: a solid solution formed by carbon and metal, and a mixture of the solid solution and carbon material. Alternatively, it may also include a solid solution formed by carbon and metal, and a mixture of the solid solution and metal, but is not limited to the above.

[0036] In some embodiments of this application, the aforementioned metal includes, but is not limited to, at least one of iron, titanium, and zirconium. Iron, titanium, and zirconium have certain oxidation resistance, which helps to extend the service life of carbon-ceramic brake discs. Correspondingly, the functional layer may include a solid solution of carbon and iron, a solid solution of carbon and titanium, or a solid solution of carbon and zirconium.

[0037] In some embodiments of this application, the metal is dispersed in the functional layer in the form of powder, and the particle size of the metal powder is in the range of 0.5 μm to 20 μm. Exemplarily, the particle size of the metal powder can be 0.8 μm, 1.0 μm, 2.0 μm, 3.0 μm, 4.0 μm, 5.0 μm, 8.0 μm, 10.0 μm, 12.0 μm, 14.0 μm, 15.0 μm, 18.0 μm, 19.0 μm, 19.5 μm, etc. Controlling the particle size distribution of the powder within the above range can improve the uniformity of material distribution in the functional layer, further stabilize the wear resistance and thermal conductivity of the functional layer, and thus contribute to further improvement in the reliability and service life of the carbon ceramic brake disc.

[0038] In some embodiments of this application, the volume percentage of metal in the functional layer is 0.1% to 30%. Exemplarily, the volume percentage of metal in the functional layer is 0.1% to 30.0%. In some specific embodiments, the volume percentage of metal in the functional layer is 15% to 30%. This facilitates controlling the iron content in the functional layer within a suitable range, so that the final functional layer has both a high coefficient of friction and good thermal conductivity, and the density of the entire carbon-ceramic brake disc is also controlled within a suitable range, which is beneficial to its braking performance. Exemplarily, the volume percentage of metal in the functional layer can be 0.1%, 0.5%, 1.0%, 2.0%, 5.0%, 8.0%, 10.0%, 12.0%, 15.0%, 18.0%, 20.0%, 22.0%, 25.0%, 28.0%, 30.0%, etc.

[0039] In some embodiments of this application, the volume ratio of silicon carbide to carbon in the functional layer is greater than that in the transition layer. This further refines the silicon carbide concentration distribution in the friction layer, thereby further mitigating the material composition variation from the load-bearing layer to the functional layer. This further improves the stability of the final carbon-ceramic brake disc, addressing issues such as uneven stress distribution or excessive stress leading to cracks caused by significant differences in composition between the friction layer and the load-bearing layer, ultimately enhancing the reliability and service life of the final carbon-ceramic brake disc.

[0040] For some embodiments of this application, please refer to Figure 2 The friction layer 20 comprises n stacked unit layers 30, wherein the n unit layers include a unit layers constituting the transition layer 21 and b unit layers constituting the functional layer 22; n is a positive integer greater than or equal to 2, a and b are each independently positive integers, and a + b = n; i+1 >I i Among them, I iThis represents the proportion of the volume of silicon carbide in the i-th unit layer to the sum of the volumes of silicon carbide and carbon; where the i-th unit layer is any layer from the 1st unit layer to the (n-1)th unit layer, and the 1st unit layer is located close to the support layer, 1≤i≤n-1, and i is a positive integer. Understandably, on the surface of the support layer, there are n stacked unit layers, including a carbon fiber reinforced silicon carbide / carbon composite unit layers and b carbon fiber reinforced silicon carbide / carbon / metal composite unit layers stacked sequentially. The a carbon fiber reinforced silicon carbide / carbon composite unit layers constitute a transition layer, and the b carbon fiber reinforced silicon carbide / carbon / metal composite unit layers constitute a functional layer; simultaneously, in these n unit layers, the proportion of the volume of silicon carbide to the sum of the volumes of silicon carbide and carbon increases layer by layer. Thus, when a>1, the gradient setting of silicon carbide and carbon content in the transition layer can be further refined (mitigated), and controlled layer by layer. The controllability of the volume content of each substance is strong, which can mitigate the thermal mismatch problem caused by the different thermal expansion coefficients of silicon carbide and carbon fiber after silicon infiltration. Simultaneously, the thermal stress generated by the increased temperature of the friction surface during braking is also alleviated, thereby further reducing the risk of cracking after repeated use of the carbon-ceramic brake disc and extending its service life. Similarly, when b>1, the functional layer itself also has a gradient setting of silicon carbide and carbon content, with the hardness gradually decreasing within the functional layer. This facilitates stress transmission at the interface between the functional layer and the transition layer, also reducing the risk of cracking after repeated use of the carbon-ceramic brake disc and extending its service life. In some specific embodiments, a>1, b>1, that is, the transition layer and functional layer simultaneously contain multiple unit layers. In some specific embodiments, b is a positive integer between 2 and 6, that is, the functional layer can contain 2, 3, 4, 5, or 6 unit layers. In some specific embodiments, a is a positive integer between 2 and 6.

[0041] In some embodiments of this application, 5% ≤ I i+1 -I i ≤20%. In other words, in the n unit layers of the friction layer, the proportion I of the volume of silicon carbide in the sum of the volumes of silicon carbide and carbon is... i The volume increases progressively from the first to the nth unit layer, and the difference in the percentage of silicon carbide and carbon in the sum of volumes between any two adjacent unit layers independently ranges from 5% to 20% (for example, the values ​​of I2-I1 and I3-I2 can be equal or unequal, and so on). For example, I i+1 -I iThe values ​​can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc. This allows for a more uniform control of the gradient change in material content within the friction layer, and the gradient is set within a more suitable range. This ensures that the gradient change in silicon carbide content within the friction layer is small, effectively alleviating thermal stress caused by heat generated during friction. Simultaneously, the stress during braking is also evenly distributed within the gradient-changing friction layer, significantly reducing the risk of brake disc cracking and extending its service life.

[0042] In some embodiments of this application, the thickness of each unit layer is independently within the range of 0.4 mm to 2.0 mm. This facilitates controlling the total thickness of the friction layer within a suitable range and also allows for a sufficient and sufficiently gentle silicon carbide volume content gradient within a relatively small friction layer thickness range. For example, the thickness of the unit layer can be 0.40 mm, 0.45 mm, 0.50 mm, 0.55 mm, 0.60 mm, 0.65 mm, 0.70 mm, 0.75 mm, 0.80 mm, 0.85 mm, 0.90 mm, 0.95 mm, 1.00 mm, 1.10 mm, 1.20 mm, 1.30 mm, 1.40 mm, 1.50 mm, 1.60 mm, 1.70 mm, 1.80 mm, 1.90 mm, 2.00 mm, etc.

[0043] In some embodiments of this application, the thickness of the friction layer is 3.0 mm to 6.0 mm. Exemplarily, the thickness of the friction layer can be 3 mm, 3.2 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.8 mm, 4.0 mm, 4.2 mm, 4.5 mm, 4.6 mm, 4.8 mm, 5.0 mm, 5.2 mm, 5.4 mm, 5.5 mm, 5.6 mm, 5.8 mm, 6.0 mm, etc. Controlling the thickness of the friction layer within the above range can reduce the overall thickness of the carbon-ceramic brake disc while ensuring its braking performance, greatly enhancing its market competitiveness.

[0044] In some embodiments of this application, the thickness of the transition layer is 2.0 mm to 5.0 mm. Exemplarily, the thickness of the transition layer can be 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3.0 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.7 mm, 3.8 mm, 3.9 mm, 4.0 mm, 4.1 mm, 4.2 mm, 4.3 mm, 4.4 mm, 4.5 mm, 4.6 mm, 4.7 mm, 4.8 mm, 4.9 mm, etc. Because the gradient of silicon carbide volume content within the transition layer can be set relatively gently, controlling the thickness of the transition layer within the above range is beneficial for reducing the overall thickness of the carbon-ceramic brake disc, while also ensuring good braking performance and reliability, and a long service life.

[0045] In some embodiments of this application, the thickness of the functional layer is 1.0 mm to 3.0 mm. Exemplarily, the thickness of the functional layer can be 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3.0 mm, etc. Controlling the thickness of the functional layer within the above range also controls the thickness of the metal-containing portion in the friction layer within a suitable range. This ensures a high metal friction coefficient for the carbon-ceramic brake disc, allowing for rapid heat conduction during braking, while also maintaining a low overall density, which is beneficial for braking performance. Furthermore, based on the gradient setting of silicon carbide volume content in the aforementioned unit layers, the functional layer can be composed of an appropriate number of unit layers, facilitating stress transmission within the carbon-ceramic brake disc and thus extending its service life.

[0046] In some embodiments of this application, the thickness of the bearing layer is 30.0 mm to 50.0 mm. Exemplarily, the thickness of the bearing layer can be 30.0 mm, 32.0 mm, 34.0 mm, 35.0 mm, 36.0 mm, 38.0 mm, 40.0 mm, 42.0 mm, 45.0 mm, 48.0 mm, 50.0 mm, etc. This provides sufficient mechanical support for the friction layer, which is beneficial to the braking effect of the carbon ceramic brake disc.

[0047] This application also provides a method for preparing a carbon ceramic brake disc, including the following steps:

[0048] S01. A carbon fiber preform is provided, comprising carbon fibers impregnated with a first slurry containing carbon powder; at least one unit layer preform is formed on each of the opposite side surfaces of the carbon fiber preform to bond the unit layer preform to the carbon fiber preform; wherein the unit layer preform comprises carbon fiber cloth; during the formation of the unit layer preform, a second slurry is injected into the unit layer preform; the second slurry comprises carbon powder and silicon carbide powder to obtain a first preform; in some embodiments of this application, the unit layer preform comprises a stacked carbon fiber unidirectional cloth and a carbon fiber mesh fabric, wherein the carbon fiber unidirectional cloth is placed close to the carbon fiber preform, and the mesh fabric and the unidirectional cloth can be bonded to form a carbon fiber unit layer. In some specific embodiments, when forming multiple unit layer preforms, the carbon fibers in the carbon fiber unidirectional cloth of two adjacent unit layer preforms have different arrangement directions.

[0049] S02. At least one unit layer preform is formed on each of the opposite sides of the first preform; wherein, during the formation process, a second slurry containing metal powder is injected into the unit layer preform to obtain a second preform; wherein, the metal powder is a metal powder that can form a solid solution with carbon; that is, the metal is a metal that can form a solid solution with carbon; in some embodiments of this application, the metal powder includes, but is not limited to, at least one of iron powder, titanium powder and zirconium powder.

[0050] S03. After carbonizing the second preform, chemical vapor deposition carbon treatment is performed, followed by high-temperature heat treatment and silicon infiltration treatment, so that the carbon fiber preform is transformed into a carbon material / silicon carbide support layer, the unit layer preform injected with the second slurry is transformed into a transition layer, and the unit layer preform injected with the second slurry containing metal powder is transformed into a functional layer, thus obtaining a carbon-ceramic brake disc. Understandably, during the transformation into a functional layer, carbon (e.g., pyrolytic carbon, carbon powder, etc.) can infiltrate into the metal powder to form a solid solution of carbon and metal. The transition layer includes a silicon carbide / carbon composite material, and the volume percentage of silicon carbide in the transition layer is greater than the volume percentage of silicon carbide in the support layer. The functional layer includes a silicon carbide / carbon / metal composite material. In the silicon infiltration reaction, in the unit layer preform, some carbon powder and some pyrolytic carbon in the second slurry react with silicon to generate silicon carbide, while the other part of the carbon powder and the other part of the pyrolytic carbon remain free carbon. The silicon carbide generated by the above reaction is included on the surface of the original silicon carbide powder (particles) in the second slurry together with the free carbon, forming a continuous phase to form a transition layer. Similarly, the above reaction also occurs in the unit layer preform containing metal. The difference is that the silicon carbide generated by the reaction will also coat the surface of the metal powder with the free carbon, thereby forming a silicon carbide / carbon / continuous phase. In the carbon fiber preform, silicon reacts with some carbon powder and some pyrolytic carbon brought in from the first slurry, and the generated silicon carbide forms a continuous phase together with the unreacted carbon.

[0051] In this embodiment of the application, during the above process, the carbon fiber still exists in the carbon ceramic brake disc in the form of a reinforcing phase.

[0052] In the above preparation method, different slurries are injected into carbon fiber products at different locations during the formation of unit layer preforms. Compared with the existing technology of directly siliconizing carbon fiber blanks, the silicon carbide concentration gradient in the final carbon ceramic brake disc can be precisely controlled. At the same time, the depth of the metal-containing part can be precisely controlled (that is, the thickness of the functional layer can be precisely controlled). Thus, multiple silicon carbide content gradients can be set in the carbon ceramic brake disc, thereby producing a carbon ceramic brake disc with a smooth surface friction layer and no cracks.

[0053] The above preparation method has simple steps, high process reliability, and high production efficiency, and can realize large-scale industrial production.

[0054] This application summarizes some embodiments in which, in steps S01 and S02 above, the forming is independently selected from at least one of needle punching and thread threading. For example, in step S01, at least one unit layer preform is needle punched or threaded onto opposite sides of the carbon fiber preform. For example, in step S02, at least one unit layer preform is further needle punched or threaded onto opposite sides of the first preform.

[0055] In some embodiments of this application, the volume ratio of silicon carbide powder to carbon powder in the second slurry used to form the transition layer and functional layer increases layer by layer with the stacking direction of the unit layer preforms. It is understood that this means that from the second slurry in step S01 to the second slurry with added metal powder in step S02, the volume ratio of silicon carbide powder to carbon powder increases layer by layer with the stacking direction of the unit layer preforms. The following is a detailed description of one possible embodiment: Nine unit preforms are formed on the surface of a carbon fiber preform to prepare a friction layer. Starting from the first unit layer preform (the one closest to the carbon fiber preform is the first unit layer preform), the carbon powder:silicon carbide powder ratio in the second slurry is controlled layer by layer to be 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8, 1:9, and 0:10. Starting from the seventh unit layer preform, metal is also added to the second slurry.

[0056] In some embodiments of this application, the volume ratio of silicon carbide powder to carbon powder in the second slurry used to form the transition layer and the functional layer increases progressively from 1:(4-9) to 10:0. This allows for the formation of multiple silicon carbide content gradients within the friction layer of the carbon-ceramic brake disc, with the gradients being relatively gentle. Exemplarily, the volume ratio of silicon carbide powder to carbon powder in the second slurry used to form the transition layer and the functional layer can be progressively increased from 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, etc., to 10:0.

[0057] In some embodiments of this application, the volume percentage of metal powder is 15% to 30% based on the dry matter in the second slurry containing added metal powder. That is, based on the total volume of carbon powder, silicon carbide powder, and metal powder in the second slurry, the volume percentage of metal powder is 15% to 30%. Exemplarily, the volume percentage of metal powder can be 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, etc. This allows for control of the metal content in the functional layer within a suitable range, ensuring that the final functional layer possesses both a high coefficient of friction and good thermal conductivity, while also maintaining the overall density of the carbon-ceramic brake disc within a suitable range, thus facilitating optimal braking performance.

[0058] In this application, S01, the aforementioned carbonization treatment refers to subjecting the second preform to high-temperature treatment in a protective atmosphere. The carbonization treatment aims to remove organic matter (including but not limited to sizing agents on the carbon fiber surface and organic matter in other raw materials) from the second preform, thereby preventing these organic substances from hindering subsequent carbon deposition in the second preform. Carbonization conditions well-known to those skilled in the art can be used, and this application does not impose any limitations on them. In some specific embodiments, the carbonization temperature is 850℃-1100℃.

[0059] In this application, in S01, the above-mentioned chemical vapor deposition carbon treatment can be to introduce pyrolyzed carbon into the second preform using a chemical vapor infiltration (CVI) process. The parameters used in the CVI process can be any parameters known in the art. Specifically, the implementation process of the above-mentioned chemical vapor deposition carbon treatment is generally as follows: using helium or hydrogen as a carrier and hydrocarbon gas (e.g., gaseous hydrocarbon) as a carbon source, under certain temperature and pressure, the gaseous carbon source enters the interior of the second preform through diffusion, flow, etc. Under high temperature, a pyrolysis reaction occurs due to thermal activation, generating pyrolytic carbon, which is deposited on the fiber surface in the form of a coating. Finally, the coatings overlap each other to become a continuous phase within the material.

[0060] In this application, in S02, high-temperature heat treatment and silicon infiltration treatment are any conditions known to those skilled in the art, and this application does not impose any limitations on them. Among them, high-temperature heat treatment is beneficial for the subsequent silicon infiltration into the carbon fiber preform.

[0061] In some embodiments of this application, the particle size of the carbon powder is in the range of 0.5 μm to 20 μm, the particle size of the silicon carbide powder is in the range of 0.5 μm to 20 μm, and the particle size of the metal powder is distributed in the range of 0.5 μm to 20 μm. Exemplarily, the particle sizes of the carbon powder, silicon carbide powder, and metal powder can each be independently 0.8 μm, 1.0 μm, 2.0 μm, 3.0 μm, 4.0 μm, 5.0 μm, 8.0 μm, 10.0 μm, 12.0 μm, 14.0 μm, 15.0 μm, 18.0 μm, 19.0 μm, 19.5 μm, etc. This facilitates obtaining a uniform second slurry and improves the wetting of the unit layer preform by the second slurry, thereby obtaining a carbon-ceramic brake disc with a uniform material composition within the layer.

[0062] This application also provides a braking system, including the carbon-ceramic brake disc described in this application embodiment, or including a carbon-ceramic brake disc prepared by the preparation method described in this application embodiment. Due to the use of the carbon-ceramic brake disc provided in this application, the braking system has better braking performance, higher reliability, and a longer service life.

[0063] In some embodiments of this application, the braking system includes a carbon ceramic brake disc, a brake caliper bracket, a brake caliper housing, and friction pads.

[0064] This application provides a vehicle that includes the braking system provided in this application. Because it incorporates the braking system provided in this application, this vehicle has good market competitiveness.

[0065] In some embodiments of this application, the means of transport includes vehicles or aircraft; wherein, vehicles include at least one of automobiles and rail trains.

[0066] The technical solution of this application will be further described in detail below with reference to several embodiments.

[0067] Example 1

[0068] (1) Provide a carbon fiber preform, the carbon fiber preform comprising carbon fiber impregnated with a first slurry containing carbon powder; needle-punch a unit layer preform on each of the opposite sides of the carbon fiber preform to bond the unit layer preform to the carbon fiber preform; wherein the unit layer preform comprises a carbon fiber unidirectional fabric and a carbon fiber mesh fabric stacked together; and during the needle-punching process, inject a second slurry into the unit layer preform to obtain a first preform; the second slurry comprises carbon powder and silicon carbide powder, wherein the mass ratio of carbon powder to silicon carbide powder is 8:2.

[0069] (2) A unit layer preform is needled on each of the opposite sides of the first preform; during the needled process, a second slurry containing iron powder (specifically, carbon powder: silicon carbide: iron powder in a volume ratio of 6:2:2) is injected into the unit layer preform to obtain the second preform;

[0070] (3) After sequentially carbonizing the second preform, chemical vapor infiltration is performed to introduce pyrolytic carbon into the second preform. Then, high-temperature heat treatment and silicon infiltration are performed sequentially to obtain the carbon-ceramic brake disc of Example 1. The thickness of the load-bearing layer is 35 mm, the thickness of the transition layer is 2 mm, the thickness of the functional layer is 2 mm, and the thickness of each individual unit layer is 2 mm. The volume percentage of iron powder in the functional layer is 15%.

[0071] Example 2

[0072] The only difference from Example 1 is that in step (2), the volume ratio of carbon powder: silicon carbide: iron powder in the second slurry is 5:3:2.

[0073] Example 3

[0074] The only difference from Example 1 is that in step (1), three unit layer preforms are formed on the opposite two sides of the carbon fiber preform, and from the first unit layer preform to the third unit layer preform, the volume ratio of carbon powder to silicon carbide powder in the second slurry is 65:35, 60:40, and 55:45 respectively (gradient is 5%).

[0075] In step (2), two unit layer preforms are formed on opposite sides of the first preform, and from the fourth unit layer preform to the fifth unit layer preform, the volume ratio of carbon powder to silicon carbide powder in the second slurry is 50:50 and 45:55 respectively (gradient of 5%); and the second slurry also contains iron powder, with the volume percentage of iron powder being 20% ​​based on the dry matter in the second slurry with added iron.

[0076] In the final carbon-ceramic brake disc, the thickness of the load-bearing layer is 33 mm, the thickness of the transition layer is 3 mm, the thickness of the functional layer is 2 mm, and the thickness of a single unit layer is 1 mm.

[0077] Example 4

[0078] The only difference from Example 3 is that in step (2), the volume percentage of iron powder is 15% based on the dry matter in the second slurry containing iron.

[0079] In the final carbon-ceramic brake disc, the thickness of the load-bearing layer is 33 mm, the thickness of the transition layer is 3 mm, the thickness of the functional layer is 2 mm, and the thickness of a single unit layer is 1 mm.

[0080] Example 5

[0081] The only difference from Example 3 is that in step (2), the volume percentage of iron powder is 30% based on the dry matter in the second slurry containing iron.

[0082] In the final carbon-ceramic brake disc, the thickness of the load-bearing layer is 33 mm, the thickness of the transition layer is 3 mm, the thickness of the functional layer is 2 mm, and the thickness of a single unit layer is 1 mm.

[0083] Example 6

[0084] The only difference from Example 3 is that in step (2), the volume percentage of iron powder is 40% based on the dry matter in the second slurry containing iron.

[0085] In the final carbon-ceramic brake disc, the thickness of the load-bearing layer is 33 mm, the thickness of the transition layer is 3 mm, the thickness of the functional layer is 2 mm, and the thickness of a single unit layer is 1 mm.

[0086] Example 7

[0087] The only difference from Example 1 is that in step (1), three unit layer preforms are needled on the opposite two sides of the carbon fiber preform, and from the first unit layer preform to the third unit layer preform, the volume ratio of carbon powder to silicon carbide powder in the second slurry is 85:15, 65:35, and 45:55 respectively (gradient is 20%).

[0088] In step (2), two unit layer preforms are formed on opposite sides of the first preform, and from the fourth unit layer preform to the fifth unit layer preform, the volume ratio of carbon powder to silicon carbide powder in the second slurry is 25:75 and 5:95 respectively (gradient of 20%); and the second slurry also contains iron powder, with the volume percentage of iron powder being 20% ​​based on the dry matter in the second slurry with added iron.

[0089] In the final carbon-ceramic brake disc, the thickness of the load-bearing layer is 33 mm, the thickness of the transition layer is 3 mm, the thickness of the functional layer is 2 mm, and the thickness of a single unit layer is 1 mm.

[0090] Example 8

[0091] The only difference from Example 1 is that in step (1), seven unit layer preforms are formed on the opposite two sides of the carbon fiber preform, and from the first unit layer preform to the seventh unit layer preform, the volume ratio of carbon powder to silicon carbide powder in the second slurry is 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7 respectively.

[0092] In step (2), unit layer preforms are formed on opposite sides of the first preform, such that from the 8th unit layer preform to the 10th unit layer preform, the volume ratio of carbon powder to silicon carbide powder in the second slurry is 2:8, 1:9, and 0:10 respectively; and the second slurry also contains iron powder, with the volume percentage of iron powder being 20% ​​based on the dry matter in the second slurry with added iron.

[0093] In the final carbon-ceramic brake disc, the thickness of the load-bearing layer is 33 mm, the thickness of the transition layer is 3.5 mm, the thickness of the functional layer is 1.5 mm, and the thickness of a single unit layer is 0.5 mm.

[0094] Example 9

[0095] The only difference from Example 8 is that iron powder is added only to the second slurry of the 10th unit layer preform. In the final carbon-ceramic brake disc, the thickness of the load-bearing layer is 36 mm, the thickness of the transition layer is 3 mm, the thickness of the functional layer is 0.5 mm, and the thickness of each unit layer is 0.5 mm.

[0096] Example 10

[0097] The only difference from Example 8 is the addition of iron powder to the second slurry of the fifth unit layer preform. In the final carbon-ceramic brake disc, the thickness of the load-bearing layer is 30 mm, the thickness of the transition layer is 3 mm, the thickness of the functional layer is 3.5 mm, and the thickness of each unit layer is 0.5 mm.

[0098] Example 11

[0099] The difference from Example 8 is that in step (1), eight unit layer preforms are formed on the opposite two sides of the carbon fiber preform, and from the first unit layer preform to the eighth unit layer preform, the volume ratio of carbon powder to silicon carbide powder in the second slurry is 85:15, 81:19, 77:23, 73:27, 70:30, 66:34, 62:38, and 58:42, respectively.

[0100] In step (2), five unit layer preforms are formed on the opposite two sides of the first preform, and from the 9th unit layer preform to the 12th unit layer preform, the volume ratio of carbon powder to silicon carbide powder in the second slurry is 50:50, 46:54, 42:58, and 38:62, respectively; and the second slurry also contains iron powder, with the volume percentage of iron powder being 20% ​​based on the dry matter in the second slurry with added iron.

[0101] In the final carbon-ceramic brake disc, the thickness of the load-bearing layer is 30 mm, the thickness of the transition layer is 4 mm, the thickness of the functional layer is 2.5 mm, and the thickness of a single unit layer is 0.5 mm.

[0102] Example 12

[0103] The difference from Example 8 is that in step (1), two unit layer preforms are formed on opposite sides of the carbon fiber preform, and from the first unit layer preform to the second unit layer preform, the volume ratio of carbon powder to silicon carbide powder in the second slurry is 80:20 and 65:35 respectively.

[0104] In step (2), two unit layer preforms are formed on opposite sides of the first preform, and from the third unit layer preform to the fourth unit layer preform, the volume ratio of carbon powder to silicon carbide powder in the second slurry is 60:40 and 35:65 respectively; and the second slurry also contains iron powder, with the volume percentage of iron powder being 20% ​​based on the dry matter in the second slurry with added iron.

[0105] In the final carbon-ceramic brake disc, the thickness of the load-bearing layer is 39 mm, the thickness of the transition layer is 1 mm, the thickness of the functional layer is 1 mm, and the thickness of a single unit layer is 0.5 mm.

[0106] To highlight the beneficial effects of the embodiments of this application, the following comparative examples are provided.

[0107] Comparative Example 1

[0108] The only difference from Example 8 is that no iron powder is added to the second slurry.

[0109] Comparative Example 2

[0110] Carbon fiber preforms are provided, which are then carbonized, pyrolytic carbon is introduced through CVI, and then subjected to high-temperature treatment and silicon infiltration treatment in sequence to obtain carbon ceramic brake discs.

[0111] Comparative Example 3

[0112] Carbon fiber preforms are provided, which are then carbonized, pyrolytic carbon is introduced via CVI, and subsequently subjected to high-temperature treatment and silicon infiltration to obtain carbon-ceramic brake discs. The silicon infiltration process uses a mixture of Si and Fe, with the Fe powder comprising 40% by volume.

[0113] Performance testing: The dynamic friction coefficient and wear rate of the carbon-ceramic brake disc samples were tested using an MM-1000 friction testing machine. The effective friction surface of the test ring had an outer diameter D75 mm and an inner diameter of 55 mm, with a specific pressure of 98 N / cm². 2 The moment of inertia is 3 kgf.cm.s 2 The linear velocity was 25 m / s. The results are summarized in Table 1.

[0114] Shear strength tests were performed on surface samples according to GB / T 15089-2001. The results are summarized in Table 1.

[0115] Table 1

[0116] Experiment number Wear amount μm / face*time coefficient of friction Surface shear strength Example 1 0.7 0.43 12MPa Example 2 0.64 0.43 13MPa Example 3 0.73 0.49 12MPa Example 4 0.69 0.44 12MPa Example 5 0.80 0.51 12MPa Example 6 1.0 0.53 11MPa Example 7 0.73 0.48 10MPa Example 8 0.68 0.45 14MPa Example 9 1.1 0.53 9MPa Example 10 1.08 0.53 7MPa Example 11 0.98 0.51 6MPa Example 12 0.88 0.49 13MPa Comparative Example 1 0.6 0.35 13MPa Comparative Example 2 0.61 0.37 5MPa Comparative Example 3 1.23 0.51 6MPa

[0117] As can be seen from the data in Table 1, the main performance of the carbon-ceramic brake disc provided in this application embodiment is significantly higher than that of the comparative brake disc. Comparing the data between the embodiments also reveals that when the silicon carbide content in the functional layer is greater than that in the transition layer, it is more conducive to improving the surface shear strength of the brake disc and reducing wear. Comparing the data of Examples 3-6 reveals that when the amount of metal powder added to the second slurry during preparation is within the range further suggested in this application (i.e., when the metal volume percentage in the functional layer is within the range further suggested in this application), it is more conducive to the performance of the carbon-ceramic brake disc. Comparing the data of Examples 8-12 reveals that when the thickness of the functional layer and the thickness of the friction layer are within the range suggested in this application, while ensuring a high coefficient of friction, it is also beneficial to reduce the wear and surface shear strength of the carbon-ceramic brake disc.

[0118] The above description is an exemplary embodiment of this application. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

Claims

1. A carbon-ceramic brake disc, characterized in that, It includes a load-bearing layer and friction layers disposed on opposite sides of the load-bearing layer; the friction layer includes n stacked unit layers, wherein the n unit layers include a unit layers constituting a transition layer and b unit layers constituting a functional layer; n is a positive integer greater than or equal to 2, a and b are each independently positive integers, a+b=n, and the transition layer is close to the load-bearing layer; The supporting layer comprises a carbon / silicon carbide composite material; the transition layer comprises a silicon carbide / carbon composite material, wherein the volume percentage of silicon carbide in the transition layer is greater than the volume percentage of silicon carbide in the supporting layer; the functional layer comprises a silicon carbide / carbon / metal composite material, wherein the metal is a metal that can form a solid solution with carbon. The n unit layers satisfy: I i+1 >I i ;I i The volume of silicon carbide in the i-th unit layer is the proportion of the sum of the volumes of silicon carbide and carbon. The i-th unit layer is any layer from the 1st unit layer to the (n-1)th unit layer, and the 1st unit layer is located close to the carrier layer, 1≤i≤n-1, and i is a positive integer.

2. The carbon ceramic brake disc according to claim 1, characterized in that, The volume ratio of silicon carbide to carbon in the functional layer is greater than the volume ratio of silicon carbide to carbon in the transition layer.

3. The carbon ceramic brake disc according to claim 1, characterized in that, 5%≤I i+1 -I i ≤20%。 4. The carbon ceramic brake disc according to claim 1, characterized in that, The thickness of each unit layer is independently within the range of 0.4 mm to 2.0 mm.

5. The carbon ceramic brake disc according to any one of claims 1 to 4, characterized in that, In the functional layer, the volume percentage of the metal is 0.1% to 30.0%.

6. The carbon ceramic brake disc according to any one of claims 1 to 4, characterized in that, The thickness of the friction layer is 3.0 mm to 6.0 mm.

7. The carbon ceramic brake disc according to any one of claims 1 to 4, characterized in that, The thickness of the transition layer is 2.0 mm to 5.0 mm; the thickness of the functional layer is 1.0 mm to 3.0 mm; and the thickness of the load-bearing layer is 30.0 mm to 50.0 mm.

8. The carbon ceramic brake disc according to any one of claims 1 to 4, characterized in that, The metal is dispersed in the functional layer in the form of powder, and the particle size of the powder is in the range of 0.5 μm to 20 μm.

9. The carbon ceramic brake disc according to any one of claims 1 to 4, characterized in that, The metal includes at least one of iron, titanium, and zirconium.

10. A method for preparing a carbon-ceramic brake disc, characterized in that, Includes the following steps: (1) Provide carbon fiber preforms, the carbon fiber preforms comprising carbon fibers impregnated with a first slurry containing carbon powder; At least one unit layer preform is formed on each of the opposite two surfaces of the carbon fiber preform to connect the unit layer preform to the carbon fiber preform; wherein the unit layer preform includes carbon fiber cloth; during the formation process, a second slurry is injected into the unit layer preform; the second slurry includes carbon powder and silicon carbide powder to obtain a first preform; (2) At least one unit layer preform is formed on each of the opposite sides of the first preform; wherein, during the formation process, a second slurry containing metal powder is injected into the unit layer preform to obtain a second preform; the metal powder is a metal powder that can form a solid solution with carbon. (3) After carbonizing the second preform, chemical vapor deposition carbon treatment is performed, followed by high-temperature heat treatment and silicon infiltration treatment, so that the carbon fiber preform is transformed into a carbon / silicon carbide composite material support layer, the unit layer preform injected with the second slurry is transformed into a transition layer, and the unit layer preform injected with the second slurry containing metal powder is transformed into a functional layer, thereby obtaining a carbon ceramic brake disc; wherein, the transition layer includes silicon carbide / carbon composite material, and the volume percentage of silicon carbide in the transition layer is greater than the volume percentage of silicon carbide in the support layer; the functional layer includes silicon carbide / carbon / metal composite material.

11. The preparation method according to claim 10, characterized in that, In the second slurry used to form the transition layer and the functional layer, the volume ratio of silicon carbide powder to carbon powder increases layer by layer with the stacking direction of the unit layer preform.

12. The preparation method according to claim 11, characterized in that, The volume ratio of silicon carbide powder to carbon powder in the second slurry used to form the transition layer and the functional layer increases layer by layer from 1:(4-9) to 10:

0.

13. The preparation method according to any one of claims 10 to 12, characterized in that, Based on the dry matter content of the second slurry containing added metal powder, the volume percentage of the metal powder is 15% to 30%.

14. A braking system, characterized in that, The braking system includes a carbon-ceramic brake disc as described in any one of claims 1 to 9, or a carbon-ceramic brake disc obtained by the preparation method described in any one of claims 10 to 13.

15. A means of transportation, characterized in that, The vehicle includes the braking system as described in claim 14.

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