High-bending-strength carbon-ceramic brake disc and preparation method thereof

Abstract

The application relates to the field of carbon ceramic composite materials, and particularly discloses a high-bending-strength carbon ceramic brake disc and a preparation method thereof. The preparation method comprises the following steps: S1, carbon cloth is directly stacked in a graphite mold after being sheared, and the carbon cloth is directly subjected to gas phase deposition after being compacted in the graphite mold; S2, high-temperature treatment, the carbon carbon body after the gas phase deposition is taken out from the graphite mold and subjected to high-temperature treatment to obtain a carbon carbon body; S3, silicon infiltration treatment, the carbon carbon body after the step S2 treatment is subjected to silicon infiltration ceramic treatment; S4, mechanical polishing, and a carbon ceramic brake disc is prepared; and the application also discloses the high-bending-strength carbon ceramic brake disc prepared by adopting the preparation method. The application has the characteristics of preparing a carbon ceramic brake disc with better bending strength.

Description

Technical Field

[0001] This application relates to the field of carbon-ceramic composite materials, and more specifically, to a high-flexural-strength carbon-ceramic brake disc and its preparation method. Background Technology

[0002] Carbon-ceramic composite brake material (hereinafter referred to as carbon-ceramic) is a new type of composite material made of two or more phases, which are reinforced with high-strength carbon fiber and pyrolytic carbon and silicon carbide as matrix. This material combines the advantages of powder metallurgy brake materials and C / C brake materials, and effectively overcomes the disadvantages of the above two materials. It has the advantages of light weight, high specific strength, high specific heat, stable friction performance, and stable mechanical properties. In particular, it has high impact toughness and strong resistance to seawater and salt spray corrosion.

[0003] Related technologies, such as those with publication numbers CN 111362714A and CN102128225A, all involve combining carbon cloth with carbon fiber mesh to form a carbon fiber preform, followed by subsequent vapor deposition and other treatments. However, it has been found that the carbon-ceramic brake discs produced by this method have low bending strength due to the needle punching process used when combining the carbon cloth with the mesh. This needle punching process damages the fibers, especially when used to prepare bicycle brake discs with a thickness of less than 2mm.

[0004] For example, Chinese patent application publication number CN 117105666 A discloses a method for preparing silicon carbide ceramic products, which uses short-cut carbon fibers as raw materials to prepare carbon-ceramic composite materials. Although the needle-punching composite process is avoided to prevent damage to the fibers, the internal fibers are relatively short due to the use of short fibers for molding, and the bending strength of the final carbon-ceramic brake disc is still relatively low.

[0005] Therefore, it is necessary to study new methods for preparing carbon-ceramic brake discs to improve their bending strength. Summary of the Invention

[0006] In order to prepare carbon ceramic brake discs with better bending strength, this application provides a high bending strength carbon ceramic brake disc and its preparation method.

[0007] In a first aspect, this application provides a method for preparing a high-bending-strength carbon-ceramic brake disc, employing the following technical solution:

[0008] A method for preparing a high-bending-strength carbon-ceramic brake disc includes the following steps:

[0009] S1. After cutting the carbon cloth, it is directly stacked and placed in a graphite mold. The carbon cloth is pressed in the graphite mold and then directly subjected to vapor deposition with the graphite mold to obtain a preform.

[0010] S2. High-temperature treatment: After the preformed body after vapor deposition is removed from the graphite mold, it is subjected to high-temperature treatment to obtain a carbon-carbon preform.

[0011] S3, Silicate diffusion treatment: The carbon-carbon preform after step S2 is subjected to silicate diffusion ceramicization treatment.

[0012] S4. Mechanical polishing to produce carbon ceramic brake discs.

[0013] By adopting the above technical solution, the traditional technology for preparing carbon-ceramic composite brake discs usually involves impregnating carbon cloth or carbon fiber preforms with resin materials such as phenolic resin and then treating them with silicon infiltration to prepare carbon-silicon composite brake discs. However, after the carbon fiber is impregnated with phenolic resin, the phenolic resin will shrink in volume during the curing process. Moreover, due to the difference in the coefficient of thermal expansion between the resin and the carbon fiber, internal stress is formed, which leads to a decrease in the bending strength of the final carbon-ceramic brake disc.

[0014] In this application, carbon cloth is directly laminated within a graphite mold for vapor deposition. Compared to conventional processes that combine carbon cloth with a mesh, this reduces needle puncture, thus minimizing damage to the carbon fibers. Furthermore, by directly pressing the carbon cloth within the graphite mold before vapor deposition, the issue of strength reduction due to short fiber compression is avoided, as is the stress caused by resin impregnation, which reduces flexural strength. Ultimately, the carbon-ceramic brake discs produced by pressing carbon cloth laminates within a graphite mold, followed by vapor deposition and silicon infiltration, exhibit excellent flexural strength, especially for thicknesses of 2 mm or less.

[0015] In addition, in this application, carbon cloth is stacked and pressed in a graphite mold to form a carbon cloth stacked structure of a certain thickness. The pressing of the stacked carbon cloth effectively removes the air gaps between the layers, increases the contact area between the carbon cloths, and significantly reduces the distance between the carbon fibers. Then, vapor deposition is performed, and the carbon source gas forms a carbon-containing gaseous intermediate at high temperature. This intermediate is deposited on the surface of the carbon cloth and combines with the carbon elements in the carbon cloth to form new chemical bonds. This allows the deposited carbon to form a chemical bond with the carbon fibers, strengthening the connection strength between the carbon cloths. When silicon infiltration ceramic treatment is performed in the subsequent process, the infiltration of silicon elements forms new chemical bonds between the carbon cloth and the deposited carbon, further strengthening the bonding force between the carbon cloth layers.

[0016] Ultimately, the preparation method of this application reduces the spacing between carbon fibers by pressing with a graphite mold, increases the contact area between carbon cloth layers, and provides more reaction sites for deposition and silicon infiltration. Then, during vapor deposition, carbon is deposited to form chemical bonds with carbon fibers, forming a certain bond. Subsequent silicon infiltration further strengthens the bond with carbon fibers. The resulting carbon-ceramic brake disc has good interlayer bonding between the carbon cloth layers, and the final carbon-ceramic brake disc has excellent shear strength performance. This solves the problem that the bonding strength between carbon cloth layers is insufficient and delamination is easy after traditional direct carbon cloth stacking deposition, resulting in insufficient shear strength performance.

[0017] Optionally, the graphite mold in step S1 includes an upper mold and a lower mold. The lower mold has a storage cavity. The upper mold includes a pressure plate and a sealing plate that fit into the storage cavity. A sealing step is formed between the pressure plate and the sealing plate. The pressure plate and the storage cavity of the lower mold have ventilation holes. The sealing plate and the lower mold are detachably connected by fasteners.

[0018] By adopting the above technical solution, carbon cloth is stacked and placed in the storage cavity of the lower mold. Then, the upper mold and the lower mold are fitted together and connected and fixed by fasteners. This allows the stacked carbon cloth to be placed in the graphite mold and pressed by the upper and lower molds. Vapor deposition is performed under the pre-tightened state of the fasteners. The carbon source gas for vapor deposition enters the graphite mold through the vent holes to perform vapor deposition on the carbon cloth. This allows the carbon cloth to undergo vapor deposition under the compressed state. During the process, the carbon fiber distance is small, and the deposited carbon and fiber carbon form chemical bonds to strengthen the bonding force between the carbon cloth and improve the shear strength.

[0019] Optionally, in step S1, the vapor phase deposition uses one or more gases selected from methane, propane, or propylene as the carbon source gas, the deposition temperature is 1000-1100℃, the deposition time is 200-500h, and the deposition pressure is 2000-4000Pa.

[0020] Optionally, the high-temperature treatment temperature in step S2 is 1800-2000℃, and the treatment time is 1-4h.

[0021] Optionally, in step S3, the amount of silicon powder added is 1-2 times the mass of the carbon-carbon preform in step S2, and the silicon infiltration temperature is 1500-1800℃, and the silicon infiltration time is 1-4h.

[0022] Optionally, in step S1, a modifier prepared by mixing polydimethylsiloxane, PAMAM, starch, and carbon nanotubes is coated onto the surface of the carbon cloth before lamination, with a coating amount of 0.3-0.5 g / cm³. 2 .

[0023] By adopting the above technical solution, the carbon cloth surface is coated with a modifier. The addition of starch and carbon nanotube particles in the modifier increases the surface roughness of the carbon cloth, which is beneficial to the mechanical interlocking of the carbon cloth layers, thereby enhancing the bonding force between the carbon cloths. More importantly, the addition of polydimethylsiloxane and PAMAM can improve the surface wettability of the carbon cloth, making the carbon cloth easier to wet and adhere during vapor deposition, which is conducive to the formation of chemical bonds between the deposited carbon and carbon fibers, thereby improving the bonding strength between carbon cloths. Moreover, during the subsequent high-temperature treatment, the polydimethylsiloxane reacts with the carbon cloth and PAMAM. In the M environment, nitrogen forms nitro-silicon bonds with silicon, while silicon forms silicon carbide with carbon in the carbon cloth. Furthermore, nitrogen atoms in PAMAM also form carbon-nitrogen bonds with carbon elements in the carbon cloth. Ultimately, carbon-nitrogen bonds, carbon-silicon bonds, and nitro-silicon bonds are formed between carbon cloths through the transition layer formed by the intermediate coating, which significantly improves the layer bonding force of the carbon cloth. Combined with the pre-tightening effect of the graphite mold, the spacing between carbon cloth fibers is small, and there are more contact and bonding sites with the modifier, resulting in better bending strength and shear strength. Moreover, polysiloxane does not shrink at high temperatures, and there is no problem of decreased bending strength due to volume shrinkage during the curing of phenolic resins.

[0024] Optionally, the modifier is prepared by the following method:

[0025] By weight, 20-30 parts of polydimethylsiloxane, 3-5 parts of polysorbate and 5-8 parts of hydroxyethyl cellulose are mixed, then 12-15 parts of PAMAM are added and mixed, followed by 3-6 parts of starch and 8-12 parts of carbon nanotubes. The mixture is stirred to obtain the modifier.

[0026] By adopting the above technical solution, the addition of polysorbate and hydroxyethyl cellulose helps to improve the uniform dispersion of starch and carbon nanotubes in PAMAM and polysiloxane, resulting in a more uniform and stable modifier. After being uniformly coated on carbon cloth, it forms more uniform particles, and the reaction sites that ultimately form chemical bonds are more evenly dispersed, resulting in better overall performance.

[0027] Optionally, the coating amount of the modifier is 0.3-0.5 g / cm³. 2 .

[0028] By adopting the above technical solution and under the above coating amount control conditions, the carbon ceramic brake disc finally obtained has excellent bending strength and excellent shear strength.

[0029] Secondly, this application provides a high-bending-strength carbon-ceramic brake disc, employing the following technical solution:

[0030] A high-bending-strength carbon-ceramic brake disc is prepared by the above-described method.

[0031] Currently, bicycle brake discs are mainly made of stainless steel. From a structural perspective, disc brakes are slightly heavier than other types of brakes. For the same model and grade of bicycle, a disc brake version will be 300-400g heavier than a rim brake version, primarily due to the increased weight on the disc brake wheel. Furthermore, during continuous long-distance downhill driving, the heat generated by friction cannot dissipate quickly enough, leading to heat accumulation and a continuous increase in brake pad temperature, resulting in thermal attenuation of friction. Carbon-ceramic composite materials possess excellent high-temperature stability. Compared to stainless steel bicycle brake discs, carbon-ceramic brake discs exhibit superior resistance to thermal attenuation under high-temperature environments, maintaining stable braking performance even under high temperatures or continuous braking. The carbon-ceramic composite bicycle brake disc developed in this application solves the problems of friction coefficient attenuation under high temperatures and wet conditions associated with current stainless steel bicycle brake discs.

[0032] Furthermore, the carbon-ceramic brake discs prepared by the carbon cloth laminate pre-tightening treatment followed by vapor deposition and ceramization technology in this application exhibit excellent bending strength. The bending strength of a 2mm thick carbon-ceramic brake disc can reach over 227MPa, effectively solving the problem of insufficient bending strength of bicycle brake discs made from carbon-ceramic composite materials with a thickness of less than 2mm. This achieves the high-performance preparation of bicycle carbon-ceramic brake discs, solves the problem of friction coefficient attenuation under high temperature and wet conditions in current bicycle stainless steel discs, and also solves the problem of insufficient bending strength of current carbon-ceramic composite brake discs.

[0033] In summary, this application has the following beneficial effects:

[0034] 1. The carbon-ceramic brake disc prepared by the carbon cloth laminate pre-tightening treatment followed by vapor deposition and ceramization technology in this application has excellent bending strength. The bending strength of a 2mm thick carbon-ceramic brake disc can reach more than 227MPa, which effectively solves the problem that the bending strength of bicycle brake discs made of carbon-ceramic composite materials is insufficient when the thickness is less than 2mm. This realizes the preparation of high-performance bicycle carbon-ceramic brake discs, solves the problem of friction coefficient decay under high temperature and wet conditions of current stainless steel bicycle discs, and also solves the problem of insufficient bending strength of current carbon-ceramic composite brake discs.

[0035] 2. In this application, carbon cloth is directly laminated in a graphite mold for vapor deposition. Compared with conventional processes that combine carbon cloth with a mesh, this reduces needle puncture, thereby reducing damage to the carbon fibers. Furthermore, by directly pressing the carbon cloth in the graphite mold before vapor deposition, the problem of strength reduction due to short fiber compression is avoided, as is the problem of reduced bending strength caused by stress generated during resin impregnation. Ultimately, the carbon-ceramic brake discs prepared by pressing carbon cloth laminated in a graphite mold before vapor deposition and silicon infiltration exhibit excellent bending strength, especially when the thickness is less than or equal to 2 mm.

[0036] 3. The preparation method of this application reduces the spacing between carbon fibers by pressing with a graphite mold, increases the contact area between carbon cloth layers, and provides more reaction sites for deposition and silicon diffusion. Then, during vapor deposition, carbon is deposited to form chemical bonds with carbon fibers, forming a certain bond. Subsequent silicon diffusion treatment further strengthens the bond with carbon fibers. The resulting carbon-ceramic brake disc has good interlayer bonding between the carbon cloth layers and excellent shear strength performance. This solves the problem of insufficient bonding strength between carbon cloth layers and easy delamination after traditional direct carbon cloth stacking deposition, which leads to insufficient shear strength performance. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the upper mold of the graphite mold in Embodiment 1 of this application;

[0038] Figure 2 This is a schematic diagram of the lower die of the graphite mold in Embodiment 1 of this application;

[0039] Figure 3 This is a schematic diagram of the product structure in Embodiment 1 of this application;

[0040] In the diagram, 1 is the upper mold; 11 is the pressure plate; 12 is the sealing plate; 13 is the sealing step; 2 is the lower mold; 21 is the storage cavity; 3 is the vent hole; and 4 is the perforation. Detailed Implementation

[0041] The following detailed description of this application is provided in conjunction with the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments are all from commercially available sources.

[0042] In the following examples, the polydimethylsiloxane used is polydimethyl silicone oil of model JN-201 from Shandong Juneng Chemical Co., Ltd.

[0043] Example 1

[0044] Reference Figure 1 and Figure 2 The graphite mold in this application includes an upper mold 1 and a lower mold 2. The lower mold 2 has a storage cavity 21. The upper mold 1 includes a pressure plate 11 and a sealing plate 12 that fit into the storage cavity 21. A sealing step 13 is formed between the pressure plate 11 and the sealing plate 12. The pressure plate 11 and the storage cavity 21 of the lower mold 2 have ventilation holes 3. The sealing plate 12 and the lower mold 2 are detachably connected by fasteners. The fasteners in this application are graphite screws and graphite nuts. The upper mold and the lower mold have through holes 4 for the screw to pass through and be fixed by nuts.

[0045] A method for preparing a high-bending-strength carbon-ceramic brake disc includes the following steps:

[0046] S1. Select 300g single-layer 0° non-woven carbon cloth and 90° non-woven carbon cloth as raw materials, and cut the carbon cloth into 180mm diameter circles. Then, stack the single-layer 0° non-woven carbon cloth and 90° non-woven carbon cloth directly and place them in the storage cavity 21 of the lower mold 2 of the graphite mold. Then, fasten the upper mold 11 and the lower mold 2 together, so that the pressure plate 11 presses the carbon cloth in the storage cavity 21, so that the carbon cloth forming size is Ф180*6mm, that is, the carbon cloth thickness in the graphite mold is 6mm and the density is 0.8g / cm³. 3 Then, the graphite screw is passed through the through holes 4 of the upper mold 1 and the lower mold 2 and fixed by the graphite nut to achieve pre-tightening of the carbon cloth after it sinks.

[0047] Then, the locked and fixed graphite mold and carbon cloth were placed into a vapor deposition furnace, and propane was used as the carbon source gas for vapor deposition to obtain a preform. The deposition temperature was 1050℃, the deposition time was 400h, the deposition pressure was 3000Pa, and the density of the preform obtained by vapor deposition was 1.5g / cm³. 3 ;

[0048] S2. High temperature treatment: After the preformed body after vapor deposition is removed from the graphite mold, it is treated at 1900℃ for 3 hours to obtain a carbon-carbon preform.

[0049] S3. Silicon infiltration treatment: The carbon-carbon preform obtained in step S2 is placed in a silicon infiltration furnace, and a vacuum is drawn to below 800 Pa. The amount of silicon powder added is 1.5 times the mass of the carbon-carbon preform in step S2. Then, the temperature is raised to the silicon infiltration temperature of 1700℃, and the silicon infiltration time is 2 hours. Then, it is cooled to room temperature in the furnace to obtain a density of 2.2 g / cm³. 3 Carbon ceramic matrix;

[0050] S4. The carbon ceramic matrix after silicon infiltration and ceramicization treatment in step S3 is mechanically polished to make the carbon ceramic matrix thickness reach 2mm, thus producing a bicycle carbon ceramic brake disc.

[0051] Example 2

[0052] A method for preparing a high-bending-strength carbon-ceramic brake disc is carried out according to the method in Example 1. The graphite mold in step S1 is the same as that in Example 1, except that:

[0053] S1. Select 200g single-layer 0° non-woven carbon cloth and 90° non-woven carbon cloth as carbon cloth raw materials, and cut the carbon cloth into 180mm diameter circles. Then, stack the single-layer 0° non-woven carbon cloth and 90° non-woven carbon cloth directly and place them in the storage cavity 21 of the lower mold 2 of the graphite mold. Then, fasten the upper mold 1 and the lower mold 2 together, so that the pressure plate 11 presses the carbon cloth in the storage cavity 21, so that the carbon cloth forming size is Ф180*6mm, that is, the carbon cloth thickness in the graphite mold is 6mm and the density is 0.6g / cm³. 3 Then, the graphite screw is passed through the through holes 4 of the upper mold 1 and the lower mold 2 and fixed by the graphite nut to achieve pre-tightening of the carbon cloth after it sinks.

[0054] The locked graphite mold and carbon cloth were then placed into a vapor deposition furnace, where methane was used as the carbon source gas for vapor deposition to obtain a preform. The deposition temperature was 1000℃, the deposition time was 500h, and the deposition pressure was 2000Pa. The density of the preform obtained by vapor deposition was 1.4 g / cm³. 3 ;

[0055] S2. High temperature treatment: After the preformed body after vapor deposition is removed from the graphite mold, it is treated at 1800℃ for 4 hours to obtain a carbon-carbon preform.

[0056] S3. Silicon infiltration treatment: The carbon-carbon preform obtained in step S2 is placed in a silicon infiltration furnace, and a vacuum is drawn to below 800 Pa. The amount of silicon powder added is one multiple of the mass of the carbon-carbon preform in step S2. Then, the temperature is raised to the silicon infiltration temperature of 1500℃, and the silicon infiltration time is 4 hours. Then, it is cooled to room temperature in the furnace to obtain a density of 2.0 g / cm³. 3 Carbon ceramic matrix.

[0057] Example 3

[0058] A method for preparing a high-bending-strength carbon-ceramic brake disc is carried out according to the method in Example 1. The graphite mold in step S1 is the same as that in Example 1, except that:

[0059] S1. Select 400g single-layer 0° non-woven carbon cloth and 90° non-woven carbon cloth as carbon cloth raw materials, and cut the carbon cloth into 180mm diameter circles. Then, stack the single-layer 0° non-woven carbon cloth and 90° non-woven carbon cloth directly and place them in the placement cavity 21 of the lower mold 2 of the graphite mold. Then, fasten the upper mold 1 and the lower mold 2 together, so that the pressure plate 11 presses the carbon cloth in the placement cavity 21, so that the carbon cloth forming size is Ф180*6mm, that is, the carbon cloth thickness in the graphite mold is 6mm and the density is 1.0g / cm³. 3 Then, the graphite screw is passed through the through holes 4 of the upper mold 1 and the lower mold 2 and fixed by the graphite nut to achieve pre-tightening of the carbon cloth after it sinks.

[0060] Then, the locked and fixed graphite mold and carbon cloth were placed into a vapor deposition furnace, and propane was used as the carbon source gas for vapor deposition to obtain a preform. The deposition temperature was 1100℃, the deposition time was 200h, the deposition pressure was 4000Pa, and the density of the preform obtained by vapor deposition was 1.6g / cm³. 3 ;

[0061] S2. High temperature treatment: After the preform after vapor deposition is removed from the graphite mold, it is treated at 2000℃ for 1 hour to obtain carbon-carbon preform.

[0062] S3. Silicon infiltration treatment: The carbon-carbon preform obtained in step S2 is placed in a silicon infiltration furnace, and a vacuum is drawn to below 800 Pa. The amount of silicon powder added is twice the mass of the carbon-carbon preform in step S2. Then, the temperature is raised to the silicon infiltration temperature of 1800℃, and the silicon infiltration time is 1 hour. Then, it is cooled to room temperature in the furnace to obtain a density of 2.4 g / cm³. 3 Carbon ceramic matrix.

[0063] Example 4

[0064] A method for preparing a high-bending-strength carbon-ceramic brake disc is carried out according to the method in Example 1. The graphite mold in step S1 is the same as that in Example 1, except that:

[0065] In step S1, the carbon cloth is cut into circular pieces with a diameter of 180 mm, a modifier is coated on the surface of the carbon cloth, and then the pieces are stacked and placed in a graphite mold. The amount of modifier coated is 0.4 g / cm³. 2 The modifier is prepared by the following method:

[0066] 25 kg of polydimethylsiloxane was mixed with 4 kg of polysorbate and 6 kg of hydroxyethyl cellulose. Then, 13 kg of PAMAM was added and mixed. After stirring, 5 kg of starch and 10 kg of carbon nanotubes were added and stirred to prepare the modifier.

[0067] Example 5

[0068] A method for preparing a high-bending-strength carbon-ceramic brake disc is carried out according to the method in Example 1. The graphite mold in step S1 is the same as that in Example 1, except that:

[0069] In step S1, the carbon cloth is cut into circular pieces with a diameter of 180 mm, a modifier is coated on the surface of the carbon cloth, and then the pieces are stacked and placed in a graphite mold. The amount of modifier coated is 0.3 g / cm³. 2 The modifier is prepared by the following method:

[0070] 20 kg of polydimethylsiloxane was mixed with 3 kg of polysorbate and 5 kg of hydroxyethyl cellulose. Then 12 kg of PAMAM was added and mixed. After stirring, 3 kg of starch and 8 kg of carbon nanotubes were added and stirred to prepare the modifier.

[0071] Example 6

[0072] A method for preparing a high-bending-strength carbon-ceramic brake disc is carried out according to the method in Example 1. The graphite mold in step S1 is the same as that in Example 1, except that:

[0073] In step S1, the carbon cloth is cut into circular pieces with a diameter of 180 mm, a modifier is coated on the surface of the carbon cloth, and then the pieces are stacked and placed in a graphite mold. The amount of modifier coated is 0.5 g / cm³. 2 The modifier is prepared by the following method:

[0074] 30 kg of polydimethylsiloxane was mixed with 5 kg of polysorbate and 8 kg of hydroxyethyl cellulose. Then 15 kg of PAMAM was added and stirred. After stirring, 6 kg of starch and 12 kg of carbon nanotubes were added and stirred to prepare the modifier.

[0075] Example 7

[0076] A method for preparing a high-bending-strength carbon ceramic brake disc is carried out according to the method in Example 4, except that PAMAM is not added to the modifier raw material.

[0077] Example 8

[0078] A method for preparing a high-bending-strength carbon ceramic brake disc is carried out according to the method in Example 4, except that starch is not added to the modifier raw materials.

[0079] Example 9

[0080] A method for preparing a high-bending-strength carbon-ceramic brake disc is carried out according to the method in Example 4, except that carbon nanotubes are not added to the modifier raw materials.

[0081] Example 10

[0082] A method for preparing a high-bending-strength carbon-ceramic brake disc is carried out according to the method in Example 4, except that starch in the modifier raw material is replaced with carbon powder in equal amounts.

[0083] Comparative Example 1

[0084] A method for preparing a high-bending-strength carbon-ceramic brake disc is carried out according to the method in Example 1, except that step S1 is specifically operated as follows:

[0085] S1. A single layer of 0° non-woven carbon fabric, a tire mesh, a 90° non-woven carbon fabric, and a tire mesh are sequentially stacked and layered, and then needle-punched to obtain a thickness of 6 mm and a density of 0.6 g / cm³. 3 The carbon fiber preform was then directly placed into a vapor deposition furnace for vapor deposition, which was the same as in Example 1.

[0086] Comparative Example 2

[0087] A method for preparing a high-bending-strength carbon-ceramic brake disc is carried out according to the method in Example 1, except that in step S1, an adhesive is coated on the circular carbon cloth after shearing the non-woven carbon cloth. The adhesive is obtained by mixing liquid phenolic resin (free phenol (mass fraction) ≤10.0%, viscosity (25℃) ≤250mPa·s, solid content (mass fraction) 50.0%-60.0%, moisture (mass fraction) ≤15.0%) and carbon powder in a mass ratio of 1:1. Then, the sheared single layer of 0° non-woven carbon cloth and 90° non-woven carbon cloth are sequentially laid in a hot press mold. After the laying is completed, the hot press mold is heated and pressurized to 160℃ and maintained at 10MPa pressure for 8 hours to obtain a carbon fiber preform. Then, the carbon fiber preform is taken out and placed in a vapor deposition furnace for vapor deposition.

[0088] Comparative Example 3

[0089] A method for preparing a high flexural strength carbon ceramic brake disc is carried out according to the method in Example 1, except that in step S1, a single layer of 0° non-woven carbon cloth and 90° non-woven carbon cloth are directly stacked in sequence in a hot press mold, and then the hot press mold is heated and pressurized to 160°C and maintained at 10MPa pressure for 8 hours to obtain a carbon fiber preform. Then the carbon fiber preform is taken out and placed in a vapor deposition furnace for vapor deposition.

[0090] Comparative Example 4

[0091] A method for preparing a high-bending-strength carbon-ceramic brake disc is carried out according to the method in Example 1, except that in step S1, the single-layer 0° non-woven carbon cloth and 90° non-woven carbon cloth are directly stacked in sequence and then placed into a vapor deposition furnace for vapor deposition instead of being placed into a mold.

[0092] Performance testing

[0093] The flexural strength and shear strength of the carbon-ceramic brake discs prepared in the embodiments and comparative examples of this application were tested respectively. The shear strength was tested according to the method specified in B / T 40388-2021 Test Method for Shear Strength of Carbon / Carbon Composite Materials, and the flexural strength was tested according to GB / T 6569-2006 standard. The test results of the carbon-ceramic composite materials are shown in Table 1 below.

[0094] Table 1:

[0095]

[0096] Referring to the test results in Table 1 above, the higher the interlayer bonding force of the carbon cloth, the higher the shear strength of the resulting carbon-ceramic brake disc. Combining the test results of Example 1 with those of Comparative Examples 1 and 4, it can be seen that in Example 1 of this application, the carbon cloth is directly laminated and then subjected to vapor deposition and other treatments, resulting in a carbon-ceramic brake disc with high bending strength, especially when the final product thickness is 2mm. Moreover, in Example 1, the carbon cloth is laminated and then subjected to vapor deposition in a graphite mold under a pre-tightened state, which allows for vapor deposition with smaller fiber spacing under the tight state, which is more conducive to the bonding between reaction sites and improves the bonding force between the carbon cloths, resulting in excellent bending strength and excellent shear strength. In contrast, in Comparative Example 1, carbon cloth is laminated with a mesh and then subjected to vapor deposition. The needle punching process damages the fibers, resulting in low bending strength of the resulting carbon-ceramic brake disc. Combining the test results of Comparative Example 4, where carbon cloth is directly laminated and then subjected to vapor deposition, although the bending strength is good, the bonding force between the carbon cloths is weak, resulting in a significant decrease in the final shear strength.

[0097] Combining the test results of Example 1 with those of Comparative Examples 2 and 3, it can be seen that when carbon cloths are bonded together with phenolic resin in Comparative Example 2, although the shear strength of the carbon ceramic brake disc is improved compared with Comparative Example 4, the bending strength of the carbon ceramic brake disc is significantly reduced due to the shrinkage caused by the curing of phenolic resin. In Comparative Example 3, carbon cloths are stacked and then directly hot-pressed and cured before vapor deposition, resulting in a carbon ceramic brake disc with low shear strength and weak bonding between carbon cloths.

[0098] Combining the test results of Examples 1 and 4-6, it can be seen that after coating the carbon cloth with the modifier, the bonding strength of the carbon cloth is further improved, and the flexural strength is also slightly improved, overcoming the problem of decreased flexural strength caused by phenolic resin bonding. Combining the test results of Example 7, it can be seen that when PAMAM is not added to the modifier, the flexural strength is comparable to that of Example 1, while the shear strength is slightly improved compared to Example 1. Combining the test results of Example 9, it can be seen that when carbon nanotubes are not added to the modifier, the shear strength is slightly reduced while the flexural strength is slightly improved. The addition of carbon nanotubes helps to improve the flexural strength, and the addition of carbon nanotubes also helps to increase the surface roughness of the carbon cloth. In the pre-tightened state in the graphite mold, the fiber distance becomes smaller, which is more conducive to mechanical interlocking. Combined with the chemical bonding effect of vapor deposition, the addition of carbon nanotubes helps to improve the shear strength. Combining the test results of Examples 8 and 10, when no starch is added to the modifier or when the starch is replaced with an equal amount of carbon powder, the shear strength is significantly lower than that of Example 4. This is mainly because the starch gradually volatilizes during the heating process, forming a certain void structure. Combined with carbon nanotubes, the carbon nanotubes subsequently form deposited carbon in the pores. While pre-tightening in the graphite mold, the mechanical interlocking between carbon cloths is further strengthened by controlling the pores and the deposition process, thereby further improving the shear strength of the carbon ceramic brake disc.

[0099] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing a high-bending-strength carbon-ceramic brake disc, characterized in that, Includes the following steps: S1. After cutting the carbon cloth, it is directly stacked and placed in a graphite mold. The carbon cloth is pressed in the graphite mold and then directly subjected to vapor deposition with the graphite mold to obtain a preform. S2. High-temperature treatment: After the preformed body after vapor deposition is removed from the graphite mold, it is subjected to high-temperature treatment to obtain a carbon-carbon preform. S3, Silicate diffusion treatment: The carbon-carbon preform after step S2 is subjected to silicate diffusion ceramicization treatment. S4. Mechanical polishing to produce carbon ceramic brake discs; In step S1, a modifier is coated on the surface of the carbon cloth before lamination. The modifier is prepared by the following method: By weight, 20-30 parts of polydimethylsiloxane, 3-5 parts of polysorbate and 5-8 parts of hydroxyethyl cellulose are mixed, then 12-15 parts of PAMAM are added and mixed, followed by 3-6 parts of starch and 8-12 parts of carbon nanotubes. The mixture is stirred to obtain the modifier.

2. The method for preparing a high bending strength carbon ceramic brake disc according to claim 1, characterized in that: The graphite mold in step S1 includes an upper mold (1) and a lower mold (2). The lower mold (2) has a storage cavity (21). The upper mold (1) includes a pressure plate (11) and a sealing plate (12) that fit into the storage cavity (21). A sealing step (13) is formed between the pressure plate (11) and the sealing plate (12). The pressure plate (11) and the storage cavity (21) of the lower mold (2) have ventilation holes (3). The sealing plate (12) and the lower mold (2) are detachably connected by fasteners.

3. The method for preparing a high bending strength carbon ceramic brake disc according to claim 2, characterized in that: The fasteners include graphite screws and graphite nuts.

4. The method for preparing a high bending strength carbon ceramic brake disc according to claim 1, characterized in that: In step S1, the vapor phase deposition uses one or more gases selected from methane, propane, or propylene as the carbon source gas, the deposition temperature is 1000-1100℃, the deposition time is 200-500h, and the deposition pressure is 2000-4000Pa.

5. The method for preparing a high bending strength carbon ceramic brake disc according to claim 1, characterized in that: In step S2, the high-temperature treatment temperature is 1800-2000℃, and the treatment time is 1-4 hours.

6. The method for preparing a high bending strength carbon ceramic brake disc according to claim 1, characterized in that: In step S3, the amount of silicon powder added is 1-2 times the mass of the carbon-carbon preform in step S2, and the silicon infiltration temperature is 1500-1800℃, and the silicon infiltration time is 1-4h.

7. The method for preparing a high bending strength carbon ceramic brake disc according to claim 1, characterized in that: The coating amount of the modifier is 0.3-0.5 g / cm³. 2 .

8. A high-strength carbon ceramic brake disc prepared by the preparation method according to any one of claims 1-7.

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