Carbon-ceramic composite material, preparation method thereof, and carbon-ceramic brake disc

Abstract

The present invention discloses a carbon-ceramic composite material, a preparation method thereof, and a carbon-ceramic brake disc. The preparation method of the carbon-ceramic composite material comprises the following steps: uniformly mixing silicon carbide, carbon fiber, and an additive to obtain a carbon-ceramic preformed powder; placing the carbon-ceramic preformed powder in a mold of a direct current rapid sintering device and applying a first preparation operation to obtain a sample to be sintered; starting the heating system of the direct current rapid sintering device, heating the sample to a first temperature, applying a second preparation operation to the sample to be sintered, then gradually heating it to a second temperature and maintaining the temperature for a period of time; shutting off the heating system and allowing it to cool naturally to obtain the carbon-ceramic composite material. The preparation method provided by the present application has a simple preparation process, low cost, and short time consumption. The carbon-ceramic composite material finally prepared has uniform phase distribution and good mechanical properties, which is conducive to a wide range of applications.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, in particular to a carbon-ceramic composite material and a preparation method thereof, and a carbon-ceramic brake disc. Background Art

[0002] With the development of modern transportation, in order to ensure the safety of the braking system and the reliability of friction transmission, the requirements for the braking system are more stringent, requiring a high and stable friction coefficient; good wear resistance; strong environmental adaptability; stable high-temperature mechanical properties; stable friction process with low noise; low cost, simple process, environmental protection and reliability.

[0003] Previous powder metallurgy metal friction materials can no longer meet the requirements. Carbon-ceramic composite materials were used as aircraft structural parts in the early days and have been used in the friction field since the 1990s. They are currently widely used in new energy vehicles, high-end fuel vehicles, and modified vehicles.

[0004] Reaction Melt Infiltration (RMI) is the mainstream carbon-ceramic brake disc production process currently on the market. Depending on the preform, it is divided into short-fiber carbon-ceramic discs and long-fiber carbon-ceramic discs. Using a vacuum sintering furnace, a layer of silicon powder is applied to the surface of the prepared preform. After heating to 1400°C to 1500°C, the silicon powder melts, and the liquid silicon penetrates into the preform through capillary action, where it chemically reacts with the preform to form silicon carbide. This method is a relatively simple process for preparing carbon ceramic, but the excessive number of processing steps and the resulting problems have limited the promotion of carbon-ceramic brake discs. Among them, it is mainly caused by two aspects. One of them is the preparation of the preform: the material distribution uniformity of the short fiber molded preform is poor, which leads to unstable surface friction performance and poor mechanical properties after the carbon ceramic disc is made; after the needle-punched preform is surface coated by the CVI process, the graphite film in some areas will be uneven, blocking the passage, affecting the infiltration of the next liquid silicon. The difference in structure between carbon felt and non-woven cloth means that only carbon felt can be used as a friction layer, and its service life is limited; the other is the residual silicon in the physical phase. The melting point of silicon is only 1410℃, which affects the high-temperature mechanical performance stability and surface friction performance stability of the carbon ceramic brake disc, and the silicon carbide generated by the reaction will block the passage, resulting in affecting the infiltration. Summary of the Invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide a carbon-ceramic composite material and a preparation method thereof and a carbon-ceramic brake disc, which can shorten the processing time, and the prepared carbon-ceramic composite material has a uniform phase and good high-temperature performance.

[0006] In order to solve the above technical problems, the present invention provides a method for preparing a carbon-ceramic composite material, which comprises the following steps: uniformly mixing silicon carbide, carbon fiber, and an additive to obtain a carbon-ceramic preformed powder; placing the carbon-ceramic preformed powder in a mold of a direct current rapid sintering device, applying a first preparation operation means, and obtaining a sample to be sintered; starting a heating system of the direct current rapid sintering device, gradually increasing the direct current to heat the sample to a first temperature, applying a second preparation operation means to the sample to be sintered, continuing to increase the direct current, and then gradually raising the temperature to a second temperature, and maintaining the temperature for a period of time; and shutting off the heating system and allowing the sample to cool naturally to obtain the carbon-ceramic composite material.

[0007] In a feasible implementation, the first preparation method includes: selecting a mold of appropriate size, isolating the interior with graphite paper, loading the carbon ceramic prefabricated powder into the mold, applying a pressure of 1 to 5 MPa to pre-compact it, and wrapping it with thermal insulation carbon felt.

[0008] In a feasible implementation, the second preparation operation means includes: gradually applying pressure to the mold at a pressure increase rate of (1-10) MPa / min, until the pressure reaches (30-50) MPa.

[0009] In a feasible implementation, the auxiliary agent is selected from at least one of Al4SiC, B4C or a metal oxide mixture; wherein the metal oxide mixture includes at least a first metal oxide and a second metal oxide; the first metal oxide is selected from at least one of Al2O3 and Y2O3, and the second metal oxide is selected from at least one of MgO, CaO, La2O3, Sc2O3 and Er2O3.

[0010] In a feasible implementation, the mass ratio of the silicon carbide, carbon fiber and additive is 1:(0.5-2):(0.01-0.1).

[0011] In a feasible implementation, the length of the carbon fiber is 5 mm to 30 mm.

[0012] In a feasible implementation, the first temperature range is 700° C., and the heating rate is 50-100° C. / min.

[0013] In a feasible implementation, the second temperature range is: 1600°C to 2100°C; the heating rate for gradually heating to the second temperature is: 10 to 50°C / min; and the holding time is 20 minutes to 2 hours.

[0014] Correspondingly, the present invention also provides a carbon-ceramic composite material, which is prepared using any of the above-mentioned preparation methods.

[0015] Correspondingly, the present invention also provides a carbon-ceramic brake disc, which is prepared using the above-mentioned carbon-ceramic composite material.

[0016] The implementation of the present invention has the following beneficial effects:

[0017] The preparation method of the carbon-ceramic composite material provided in the embodiment of the present application uses silicon carbide powder and carbon fiber staple as raw materials, mixes to form a uniform powder, uses a flash firing process, and directly sintered. The preparation process is simple, low-cost, and short-time. In addition, the raw materials used in the preparation method provided in the embodiment of the present application do not use silicon monomers, and there is no need to melt silicon into liquid silicon, and no infiltration process is required. It is precisely because it does not contain free silicon that the carbon-ceramic composite material prepared by the preparation process provided in the present application has good high-temperature performance. At the same time, since the raw materials and preparation process of the embodiment of the present application are simple, the raw materials can be mixed evenly, and the carbon-ceramic composite material finally prepared has a uniform phase distribution and good mechanical properties, which is conducive to a wide range of applications.

[0018] The carbon-ceramic composite material provided in the embodiments of the present application has the advantages of uniform phase, excellent mechanical properties, stable friction performance, high temperature resistance, high density, etc., and is conducive to a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a SEM image of the fracture surface of the carbon-ceramic composite material prepared in Example 1 (1000 times);

[0020] Figure 2 This is a SEM image (5000 times) of the fracture surface of the carbon-ceramic composite material prepared in Example 1;

[0021] Figure 3 This is an EDS layered image of the carbon-ceramic composite material prepared in Example 1;

[0022] Figure 4 EDS layered image of the carbon-ceramic composite material prepared in Example 1 - C;

[0023] Figure 5 This is the EDS layered image of the carbon-ceramic composite material prepared in Example 1 - Si. DETAILED DESCRIPTION

[0024] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] The present invention provides a method for preparing a carbon-ceramic composite material. The method comprises the following steps:

[0027] S110, mixing silicon carbide, carbon fiber and additives uniformly to obtain carbon ceramic prefabricated powder.

[0028] The process of uniformly mixing the silicon carbide, carbon fiber, and additives can include simultaneously adding the silicon carbide, carbon fiber, and additives to a stirring device and stirring them uniformly, thereby evenly distributing the raw materials. Alternatively or preferably, the additives and carbon fiber can be mixed uniformly before adding the silicon carbide powder. Alternatively or preferably, the additives and silicon carbide powder can be mixed uniformly before adding the carbon fiber. This facilitates thorough mixing of the raw materials and, in turn, facilitates uniform distribution of the physical phases of the final product.

[0029] Furthermore, in a feasible embodiment, the auxiliary agent is selected from at least one of Al4SiC, B4C or a metal oxide mixture; wherein the metal oxide mixture includes at least a first metal oxide and a second metal oxide; the first metal oxide is selected from at least one of Al2O3 and Y2O3, and the second metal oxide is selected from at least one of MgO, CaO, La2O3, Sc2O3 and Er2O3.

[0030] Optionally or preferably, the metal oxide mixture is selected from at least one of the following combinations: Al2O3 and Y2O3; Al2O3 and CaO; Al2O3 and MgO; Al2O3, Y2O3, MgO and CaO; Y2O3 and La2O3; Y2O3 and S2O3; or Al2O3 and Er2O3.

[0031] Optionally or preferably, the metal oxides are mixed to form a mixture of Al2O3 and Y2O3. Al2O3 and Y2O3 can form a yttrium aluminum garnet (YAG) liquid phase at 1760°C, promoting densification. Furthermore, the molar ratio of Al2O3 to Y2O3 is 1:(0.4-0.6).

[0032] Optionally or preferably, the metal oxides are mixed to form a mixture of Al2O3 and CaO. Al2O3 and CaO form a liquid phase at 1360-1500°C, promoting densification. Furthermore, the molar ratio of Al2O3 to CaO is 1:(0.8-1.2).

[0033] Optionally or preferably, the metal oxides are mixed to form a mixture of Al2O3 and MgO. Al2O3 and MgO form magnesia-alumina spinel at 1450-1600°C, forming a liquid phase and promoting densification. Furthermore, the molar ratio of Al2O3 to MgO is 1:(0.4-0.6).

[0034] Optionally or preferably, the metal oxide mixture is a mixture of Al2O3, Y2O3, MgO, and CaO. Al2O3, Y2O3, MgO, and CaO can work together to form a liquid phase, promoting densification. Furthermore, the molar ratio of Al2O3, Y2O3, MgO, and CaO is 1:(0.4-0.6):(0.1-0.2):0.1.

[0035] Optionally or preferably, the metal oxide mixture is a mixture of Y2O3 and La2O3. At temperatures above 2000°C, the rare earth elements in the mixture of Y2O3 and La2O3 can react with oxygen on the silicon carbide surface, reducing the oxygen content, promoting densification, and improving thermal conductivity. Furthermore, the molar ratio of Y2O3 to La2O3 is (0.4-0.6):1.

[0036] Optionally or preferably, the metal oxide mixture is a mixture of Y2O3 and S2O3. At temperatures above 2050°C, the rare earth elements in the mixture of Y2O3 and S2O3 can react with oxygen on the silicon carbide surface, reducing the oxygen content, promoting densification, and improving thermal conductivity. Furthermore, the molar ratio of Y2O3 to S2O3 is (0.2-0.4):1.

[0037] Alternatively or preferably, the metal oxide mixture is a mixture of Al2O3 and Er2O3. The mixture of Al2O3 and Er2O3 can form Er3Al5O 12 , promoting grain refinement and improving performance. Furthermore, the molar ratio of Al2O3 to Er2O3 is (0.4-0.6):1.

[0038] Optionally or preferably, the auxiliary agent is Al4SiC. Al4SiC has low density and high melting point, decomposes at 1700°C, carbon can promote grain refinement, and Al activator enhances grain boundary diffusion.

[0039] Optionally or preferably, the auxiliary agent is B4C. B4C can form a eutectic phase with silicon carbide to promote densification.

[0040] In a feasible embodiment, optionally or preferably, the mass ratio of the silicon carbide, carbon fiber, and additive is 1:(0.5-2):(0.01-0.1). The mass ratio of the silicon carbide, carbon fiber, and additive is 1:(0.5-1.5):0.05. Alternatively or preferably, the mass ratio of the silicon carbide, carbon fiber, and additive is 1:0.5:0.05, 1:1:0.05, or 1:1.5:0.05.

[0041] In one feasible embodiment, the length of the carbon fiber is 5 mm to 30 mm. Alternatively or preferably, the length of the carbon fiber is 10 to 25 mm. Alternatively or preferably, the length of the carbon fiber is 10 to 20 mm. Alternatively or preferably, the length of the carbon fiber is 10 mm, 15 mm, or 20 mm. Alternatively or preferably, the length of the carbon fiber is 15 mm.

[0042] S120, placing the carbon ceramic preformed powder in a mold of a direct current rapid sintering device, applying a first preparation operation means, and obtaining a sample to be sintered.

[0043] In one feasible embodiment, the first preparation method includes: selecting a mold of appropriate size, insulating the interior with graphite paper, placing the carbon ceramic preform powder into the mold, applying a pressure of 1 to 5 MPa for pre-compaction, and wrapping it with insulating carbon felt. Pre-compaction can significantly increase the initial density of the sample and reduce porosity. High-density samples are more likely to form a dense structure during DC rapid sintering, improving the material's mechanical strength and durability. Pre-compaction can reduce porosity and voids in the sample, making the material more uniform. A uniform structure reduces cracks and defects, improving the overall performance and reliability of the material. Pre-compaction allows the sample to be better formed in the mold, ensuring consistent shape and size. Consistent shape and size facilitate subsequent processing and application, improving product qualification rate and production efficiency. Pre-compaction promotes uniform distribution of fillers and additives throughout the sample. Evenly distributed fillers and additives can better perform their functions, improving the material's overall properties, such as electrical and thermal conductivity. Pre-compacted samples have higher density and fewer pores, resulting in shorter heat conduction paths. During rapid sintering, or flash sintering, heat is more evenly transferred to the sample, preventing local overheating and uneven sintering. Pre-compacting strengthens the interfacial bonding between carbon fibers and other fillers. Good interfacial bonding improves the material's mechanical properties and fatigue resistance. Pre-compacting also results in a smoother and flatter sample surface. This smooth surface improves the material's appearance, reduces surface defects, and enhances the product's market competitiveness.

[0044] S130, starting the heating system of the DC rapid sintering device, gradually increasing the DC current for heating, after heating to the first temperature, applying the second preparation operation means to the sample to be sintered, continuing to increase the DC current, and then gradually raising the temperature to the second temperature, and keeping it warm for a period of time.

[0045] Furthermore, the DC current is increased at a rate of 1000A per minute. Increasing the DC current here refers to increasing the DC current applied to both ends of the DC rapid sintering device's mold, that is, directly acting on both ends of the carbon ceramic preform. The DC current heats the carbon ceramic preform.

[0046] In one feasible embodiment, the second preparation operation comprises gradually applying pressure to the mold at a pressure increase rate of 10 MPa / min, reaching a pressure of 30 MPa to 50 MPa. Rapid pressure increases can cause rapid changes in pressure inside and outside the material, generating significant thermal and mechanical stresses. These stresses can lead to cracks, delamination, or fractures within the material, seriously affecting the material's mechanical strength and integrity. Rapid pressure increases can cause gas to rapidly dissolve or escape within the material. Uneven gas dissolution and escape can form bubbles or pores within the material, reducing its density and mechanical properties. Rapid pressure increases can lead to uneven phase transitions within the material. Different regions may undergo different phase transitions, resulting in an uneven microstructure and affecting its physical and chemical properties. Rapid pressure increases can prevent certain chemical reactions from fully proceeding. Incompletely reacted substances may remain in the material, affecting its purity and performance, and even causing subsequent instability and degradation. Rapid pressure increases can result in excessive pressure gradients inside and outside the material. These pressure gradients can lead to stress concentrations within the material, increasing the risk of cracks and defects. Rapid pressure increase can cause the surface pressure of the material to rise rapidly, while the internal pressure lags behind. This pressure differential can lead to different expansion coefficients between the surface and interior of the material, inducing internal stress and further increasing the risk of cracks. Rapid pressure increase can prevent the material from fully densifying during the sintering process. This reduces the material's density and increases its porosity, leading to a decline in mechanical properties. Rapid pressure increase places higher demands on the equipment's pressure resistance and safety. If the equipment cannot withstand the pressure fluctuations caused by rapid pressure increase, it may cause equipment damage or safety accidents. However, too slow a pressure increase rate significantly increases the overall heat treatment process time, extending the production cycle, reducing production efficiency, and increasing production costs. A prolonged pressure increase process consumes more energy. Increased energy consumption and production costs are not in line with energy conservation and emission reduction requirements. While slow pressure increase facilitates the gradual release of volatile substances, if the pressure increase is too slow, these substances may begin to release at lower pressures, resulting in incomplete release. Residual volatile substances may recondense or react in the subsequent high-pressure stage, affecting the purity and performance of the material. Excessively slow pressure increase rates can lead to uneven structural changes in the material at different stages. The microstructure and properties of the material may vary in different areas, affecting the overall uniformity and consistency. A pressurization rate that is too slow may cause pyrolysis products (such as gas and liquid) to begin to form at lower pressures, but the discharge rate is slow. These products may accumulate inside the material, resulting in increased porosity, affecting the density and mechanical properties of the material. A pressurization rate that is too slow may result in weak interfacial bonding inside the material. Poor interfacial bonding will affect the mechanical properties and durability of the material. A pressurization rate that is too slow will cause the equipment to operate for a longer time under high pressure. The utilization rate of the equipment will decrease and the maintenance cost will increase. A pressurization rate that is too slow may make temperature control more difficult because the changes in temperature and pressure need to be coordinated.Improper temperature control may affect the performance and quality of the material.

[0047] In a feasible embodiment, the first temperature range is 700°C, and the heating rate is 50°C / min to 100°C / min. The sintering temperature is determined by different sintering aids. If the temperature is not appropriate, the product cannot be formed or has poor performance.

[0048] In a feasible embodiment, the second temperature range is: 1600℃~2100℃. The heating rate for gradually heating to the second temperature is: 10℃ / min~50℃ / min. If the heating rate is too fast, the product will have a local temperature that is too high, affecting the performance, and if it is too slow, it will affect the efficiency. A too slow heating rate will significantly increase the time of the entire heat treatment process. The production cycle is extended, resulting in reduced production efficiency and increased production costs. A long heating process will consume more energy. Energy consumption increases, production costs rise, and it does not meet the requirements of energy conservation and emission reduction. Although slow heating helps the gradual escape of volatile substances, if the temperature rises too slowly, these substances may begin to volatilize at a lower temperature, resulting in incomplete escape. Residual volatile substances may re-condense or react in the subsequent high-temperature stage, affecting the purity and performance of the material. A too slow heating rate may cause uneven structural changes in the material at different stages. The microstructure and properties of the material may differ in different regions, affecting the overall uniformity and consistency. Too slow a heating rate may cause pyrolysis products (such as gases and liquids) to initially form at lower temperatures, but their release rate is slow. These products may accumulate within the material, increasing porosity and affecting the material's density and mechanical properties. Too slow a heating rate can also lead to weak interfacial bonding within the material. Poor interfacial bonding can affect the material's mechanical properties and durability. Too slow a heating rate can extend the time equipment needs to operate at high temperatures, reducing equipment utilization and increasing maintenance costs. Furthermore, rapid heating increases the temperature difference between the inside and outside of the material, generating significant thermal stress. Thermal stress can cause cracks, delamination, or fractures within the material, seriously affecting its mechanical strength and integrity. Rapid heating can rapidly vaporize volatile substances (such as water and solvents) within the material. Gases cannot escape quickly, potentially forming bubbles or pores within the material, reducing its density and mechanical properties. Rapid heating can also lead to uneven phase transitions within the material. Different regions may undergo different phase transitions, resulting in an uneven microstructure and affecting its physical and chemical properties. Rapid heating may cause pyrolysis products (such as gas and liquid) to be generated rapidly inside the material. These products may not be discharged in time, resulting in increased pressure inside the material, causing cracks or other defects. Rapid heating will cause the surface temperature of the material to rise rapidly, while the internal temperature will lag behind. This temperature difference may cause the expansion coefficients of the surface and the interior to be different, causing internal stress and further increasing the risk of cracks. Rapid heating may prevent the material from being fully densified during the sintering process. The density of the material decreases and the porosity increases, resulting in a decrease in mechanical properties. Although rapid heating can shorten the heating time, it may result in energy waste. Excessively high heating rates may reduce the energy efficiency of the equipment and increase production costs. Furthermore, the selection of the second temperature depends on the type and proportion of the additives.

[0049] In a feasible embodiment, the holding time is 20 minutes to 2 hours. Furthermore, the holding time needs to be adjusted accordingly according to different additives and parameter conditions.

[0050] The DC rapid sintering device includes a pressurizing device, a vacuum chamber, a heating system, a high-voltage DC flash power supply, a control system, and a cooling system. The raw materials are placed in a mold composed of high-temperature ceramic and graphite, located at the center of the vacuum chamber and constrained by the pressure of the pressurizing system. The heating system enters the vacuum chamber through the outer wall of the vacuum chamber to heat the carbon ceramic preform powder. The high-voltage DC flash power supply applies voltage to the graphite mold via water-cooled copper electrodes at the upper and lower pressure heads of the pressurizing device. During use, the heating element of the auxiliary heating system provides the required pre-heating temperature for the carbon ceramic preform powder before flash sintering, while a certain pressure is applied by the pressurizing device. When the temperature reaches the set value, the high-voltage DC flash power supply applies a DC electric field to cause flash sintering, achieving low-temperature rapid densification of the carbon ceramic preform powder. The high-voltage DC flash power supply is controlled by a program, switching from voltage control to current control when flash sintering occurs, and heating ends after a certain period of time, followed by cooling to room temperature.

[0051] S140, turning off the heating system and cooling naturally to obtain a carbon-ceramic composite material.

[0052] The preparation method of the carbon-ceramic composite material provided in the embodiment of the present application uses silicon carbide powder and carbon fiber staple as raw materials, mixes to form a uniform powder, uses a flash firing process, and directly sintered. The preparation process is simple, low-cost, and short-time. In addition, the raw materials used in the preparation method provided in the embodiment of the present application do not use silicon monomers, and there is no need to melt silicon into liquid silicon, and no infiltration process is required. It is precisely because it does not contain free silicon that the carbon-ceramic composite material prepared by the preparation process provided in the present application has good high-temperature performance. At the same time, since the raw materials and preparation process of the embodiment of the present application are simple, the raw materials can be mixed evenly, and the carbon-ceramic composite material finally prepared has a uniform phase distribution and good mechanical properties, which is conducive to a wide range of applications.

[0053] In addition, the preparation method of the carbon-ceramic composite material provided in the embodiment of the present application is simple, convenient and low-cost in terms of raw material acquisition. Relying on the development of domestic carbon fiber, carbon fiber staple is guaranteed in terms of price, supply and performance. The development of the photovoltaic industry has led to a stable supply of micron-sized silicon carbide powder. Therefore, it is more convenient and cheaper to obtain raw materials and cost than the existing technology; the preparation method of the carbon-ceramic composite material provided in the embodiment of the present application does not require the preparation of a preform, has fewer steps, and greatly shortens the preparation time and cost. The preparation method of the carbon-ceramic composite material provided in the embodiment of the present application is short in preparation time and can be completed in only a few hours. A rapid hot pressing (FHP) process is used, and a DC power supply forms a DC electric field to assist sintering, preventing grain growth and obtaining better mechanical properties. The preparation method of the carbon-ceramic composite material provided in the embodiment of the present application does not require the participation of a reaction. The present invention uses silicon carbide powder for direct sintering. The sintering process does not require the participation of a reaction, so there is no low-melting-point component in the phase that affects high-temperature performance. Existing technologies require preforms, which can lead to uneven physical properties in the finished product and unstable surface friction performance over long periods of use. The carbon-ceramic composite material prepared by the method for preparing the carbon-ceramic composite material provided in the embodiments of the present application exhibits high stability in mechanical and frictional properties. The carbon-ceramic composite material prepared by the method for preparing the carbon-ceramic composite material provided in the embodiments of the present application exhibits high density. The density of the sintered sample of the present invention is close to fully dense, preventing pores from forming defects within the sample and leading to performance degradation.

[0054] The existing technology prepares a preform and then uses reactive melt infiltration (RMI) to melt silicon into a liquid and infiltrate it into the preform, generating silicon carbide through reaction. After cooling, a carbon ceramic material is obtained. The present invention uses a rapid hot pressing (FHP) process to directly press the prepared powder into a carbon ceramic material, shortening the preparation time from one week to a few hours.

[0055] Existing carbon ceramic materials produced through reactive melt infiltration (RMI) contain numerous pores within the sample, preventing full densification. They also contain a significant amount of unreacted silicon, which impacts the material's mechanical properties and surface friction. The present invention utilizes a rapid hot pressing (FHP) process to directly sinter silicon carbide powder, effectively bonding it to the carbon fiber surface. This results in near-fully dense material without any reaction, eliminating the need for unreacted silicon to impact performance.

[0056] Existing carbon ceramic materials, due to structural issues with the preform, have unstable surface friction properties. Only the surface layer can be used as a friction material. This layer wears away during use, causing the surface friction to become unstable and affecting performance. However, the present invention utilizes powder sintering, eliminating these structural differences and enabling a significantly larger usable volume compared to existing technologies.

[0057] Accordingly, embodiments of the present application also provide a carbon-ceramic composite material. The carbon-ceramic composite material is prepared using any of the aforementioned preparation methods. The carbon-ceramic composite material provided in embodiments of the present application has advantages such as uniform phase, excellent mechanical properties, stable friction performance, high temperature resistance, and high density, and is therefore suitable for a wide range of applications.

[0058] Accordingly, embodiments of the present application also provide a carbon-ceramic brake disc. The carbon-ceramic brake disc is prepared using the aforementioned carbon-ceramic composite material. The carbon-ceramic brake disc described in embodiments of the present application has all the advantages of the aforementioned carbon-ceramic composite material, which will not be further elaborated here.

[0059] With reference to the above implementation content, in order to make the technical solution of this application more specific, clear and easy to understand, the technical solution of this application is now given as an example. However, it should be noted that the content to be protected by this application is not limited to the following embodiments.

[0060] Example 1

[0061] Silicon carbide, carbon fiber and additive B4C are evenly mixed in a ratio of 1:0.66:0.05 to obtain a carbon ceramic preform powder;

[0062] A mold with an inner diameter of 80 mm was selected, the interior of which was insulated with graphite paper. The carbon ceramic prefabricated powder was placed into the mold, pre-compacted with a pressure of 5 MPa, and wrapped with thermally insulating carbon felt to prepare the sample to be sintered.

[0063] Apply a preload of 5 MPa to the sample to be sintered, align the infrared ray with the temperature measuring hole, start the heating system, and increase the current by 1000 A per minute. After heating to 700°C, apply a pressure of 50 MPa to the mold at a pressure increase rate of 5 MPa / min, and increase the temperature at a rate of 50°C / min to 1900°C. Hold the temperature for 30 minutes.

[0064] After sintering, the heating system was turned off and the sintered sample was allowed to cool naturally in the mold to obtain a carbon-ceramic composite material.

[0065] Figure 1 This is a SEM image of the fracture surface of the carbon-ceramic composite material prepared in Example 1 (1000 times);

[0066] Figure 2 This is a SEM image (5000 times) of the fracture surface of the carbon-ceramic composite material prepared in Example 1;

[0067] Figure 3 This is an EDS layered image of the carbon-ceramic composite material prepared in Example 1;

[0068] Figure 4 EDS layered image of the carbon-ceramic composite material prepared in Example 1 - C;

[0069] Figure 5 This is the EDS layered image of the carbon-ceramic composite material prepared in Example 1 - Si.

[0070] Example 2

[0071] The method is basically the same as Example 1, except that the mass ratio of silicon carbide, carbon fiber and additive B4C is 1:1:0.05.

[0072] Example 3

[0073] The method is basically the same as Example 1, except that the mass ratio of silicon carbide, carbon fiber and additive B4C is 1:2:0.05.

[0074] Example 4

[0075] It is basically the same as Example 1, except that the additive is a metal oxide mixture, the metal oxide mixture is a mixture of Al2O3 and Y2O3, the molar ratio of Al2O3 and Y2O3 is 1:0.55, and the mass ratio of silicon carbide, carbon fiber and additive is 1:2:0.05. After heating to 700°C, a pressure of 40 MPa is applied to the mold at a pressure increase rate of 5 MPa / min, and the temperature is increased at a heating rate of 30°C / min to 1600°C and kept warm for 20 minutes.

[0076] Example 5 is basically the same as Example 1, except that the auxiliary agent is a metal oxide mixture, the metal oxide mixture is a mixture of La2O3 and Y2O3, the molar ratio of La2O3 and Y2O3 is 1:0.35, and the mass ratio of silicon carbide, carbon fiber and auxiliary agent is 1:2:0.05. After heating to 700°C, a pressure of 40 MPa is applied to the mold at a pressure increase rate of 10 MPa / min, and the temperature is increased at a heating rate of 30°C / min to 2100°C and kept warm for 2 hours.

[0077] Example 6

[0078] The method is basically the same as Example 4, except that the mass ratio of silicon carbide, carbon fiber and additive is 1:2:0.01.

[0079] Example 7

[0080] The method is basically the same as Example 4, except that the mass ratio of silicon carbide, carbon fiber and additive is 1:2:0.1.

[0081] Example 8

[0082] It is basically the same as Example 4, except that after heating to 700°C, a pressure of 40 MPa is applied to the mold at a pressure increase rate of 10 MPa / min, the temperature is increased at a heating rate of 50°C / min to 1700°C, and the temperature is kept at this temperature for 20 minutes.

[0083] Example 9

[0084] It is basically the same as Example 4, except that the additive is a metal oxide mixture, the metal oxide mixture is a mixture of Al2O3, Y2O3, MgO, and CaO, the molar ratio of Al2O3, Y2O3, MgO, and CaO is 1:0.55:0.15:0.1, and the mass ratio of silicon carbide, carbon fiber, and additive is 1:2:0.05. After heating to 700°C, a pressure of 40 MPa is applied to the mold at a pressure increase rate of 5 MPa / min, and the temperature is increased at a heating rate of 30°C / min to 1800°C and kept warm for 20 minutes.

[0085] Example 10

[0086] It is basically the same as Example 4, except that the auxiliary agent is Al4Si3C. After heating to 700°C, a pressure of 40 MPa is applied to the mold at a pressure increase rate of 5 MPa / min, and the temperature is increased at a heating rate of 30°C / min to 1750°C and kept warm for 20 minutes.

[0087] Comparative Example 1

[0088] Using carbon fiber staple as raw material and phenolic resin as adhesive, a preform is made by molding and carbonized at 900-1000°C, a process that usually takes several hours to several days; then silicon is infiltrated using the RMI process, which usually takes 3-7 days.

[0089] Comparative Example 2

[0090] Using long fibers as raw materials, a 2.5D fiber preform is made through a needle punching process, and then densified by CVI or liquid phase impregnation. Carbonization is carried out at 900-1000°C. CVI densification takes about a week, while liquid phase impregnation densification takes 2-3 days. Then, siliconization is carried out by RMI process, which usually takes 3-7 days.

[0091] Performance testing

[0092] 1. The relative density (%) and density (g / cm 3 );

[0093] 2. Measure the surface hardness (HV) at a pressure of 1-5 kg ​​in accordance with GB / T 16534-2009 "Test Method for Hardness of Fine Ceramics at Room Temperature";

[0094] 3. Measure the flexural strength (MPa) according to GB / T 6569, Test Method for Flexural Strength of Fine Ceramics;

[0095] The performance test results are shown in the following table:

[0096]

[0097] As can be seen from the above table, the carbon-ceramic composite materials prepared in Examples 1 to 10 have better properties than the carbon-ceramic composite materials prepared in Comparative Examples 1 and 2.

[0098] From the above table and Figures 1 to 5 It can be seen that in the carbon-ceramic composite material prepared in Example 1, the carbon fibers are evenly dispersed, presenting a random and unoriented distribution, with high density and no obvious pores or defects. The carbon-ceramic composite material prepared in Example 1 has better performance than the carbon-ceramic composite materials prepared in other examples.

[0099] While the basic concepts have been described above, it will be apparent to those skilled in the art that the detailed disclosure is merely illustrative and does not limit this specification. Although not explicitly stated herein, various modifications, improvements, and revisions to this specification may be made by those skilled in the art. Such modifications, improvements, and revisions are suggested in this specification and remain within the spirit and scope of the exemplary embodiments of this specification.

[0100] This specification also uses specific terms to describe the embodiments of this specification. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "one embodiment," "an embodiment," or "an alternative embodiment" two or more times in different locations in this specification do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics of one or more embodiments of this specification may be appropriately combined.

[0101] In addition, unless explicitly stated in the claims, the order of the processing elements and sequences, the use of alphanumeric characters, or the use of other names described in this specification are not intended to limit the order of the processes and methods of this specification. Although the above disclosure discusses some of the invention embodiments currently considered useful through various examples, it should be understood that such details are only for illustrative purposes, and the appended claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that are consistent with the spirit and scope of the embodiments of this specification.

[0102] Similarly, it should be noted that, in order to simplify the presentation of this specification and thus facilitate understanding of one or more embodiments of the invention, the foregoing descriptions of the embodiments of this specification sometimes combine multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not imply that the subject matter of this specification requires more features than those recited in the claims. In fact, an embodiment may have fewer features than all of the features of a single disclosed embodiment.

[0103] In some embodiments, numbers are used to describe the quantity of components and attributes. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise stated, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the description and claims are approximate values, which may change according to the required characteristics of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of this specification are approximate values, in specific embodiments, the settings of such numerical values ​​are as accurate as possible within the feasible range.

[0104] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, and documents, cited in this specification is hereby incorporated by reference in its entirety. This includes application history documents that are inconsistent with or conflict with the content of this specification, as well as documents (currently or subsequently attached to this specification) that limit the broadest scope of the claims of this specification. It should be noted that if the descriptions, definitions, and / or terminology used in the accompanying materials are inconsistent or conflicting with the content of this specification, the descriptions, definitions, and / or terminology used in this specification will control.

[0105] Finally, it should be understood that the embodiments described in this specification are intended only to illustrate the principles of the embodiments of this specification. Other variations may also fall within the scope of this specification. Therefore, by way of example and not limitation, alternative configurations of the embodiments of this specification may be considered consistent with the teachings of this specification. Accordingly, the embodiments of this specification are not limited to the embodiments explicitly described and illustrated in this specification.

Claims

1. A carbon ceramic brake disc, characterized in that: The carbon-ceramic brake disc is made of a carbon-ceramic composite material, and the preparation method of the carbon-ceramic composite material includes the following steps: The silicon carbide, carbon fiber and additive are uniformly mixed to obtain a carbon ceramic preformed powder, wherein the mass ratio of the silicon carbide, carbon fiber and additive is 1: (0.5-2): (0.05-0.1); The auxiliary agent is selected from at least one of B4C or a metal oxide mixture; the metal oxide mixture is a mixture of Al2O3 and Y2O3 or a mixture of Al2O3, Y2O3, MgO and CaO; Placing the carbon ceramic preformed powder in a mold of a direct current rapid sintering device, and applying a first preparation operation to obtain a sample to be sintered; Starting the heating system of the DC rapid sintering device, gradually increasing the DC current to heat, and after heating to the first temperature, applying a second preparation operation to the sample to be sintered, continuing to increase the DC current, and then gradually raising the temperature to the second temperature, and holding the temperature for a period of time; the second preparation operation includes: gradually applying pressure to the mold at a pressure increase rate of 1MPa / min-10MPa / min to a pressure of 30MPa-50MPa; the second temperature range is 1600°C-2100°C; the heating rate for gradually raising the temperature to the second temperature is 10°C / min-50°C / min; and the holding time is 20min-2h; The heating system is turned off and the mixture is cooled naturally to obtain a carbon-ceramic composite material.

2. The carbon-ceramic brake disc according to claim 1, characterized in that: The first preparation operation means includes: selecting a mold of appropriate size, isolating the interior with graphite paper, loading the carbon ceramic prefabricated powder into the mold, applying a pressure of 1MPa-5MPa to pre-compact it, and wrapping it with thermal insulation carbon felt.

3. The carbon-ceramic brake disc according to claim 1, characterized in that: The length of the carbon fiber is 5mm-30mm.

4. The carbon-ceramic brake disc according to claim 1, characterized in that: The first temperature is 700° C., and the heating rate is 50° C. / min-100° C. / min.

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