Preparation method of carbon ceramic material brake disc resistant to high-temperature oxidation working condition

Abstract

The application relates to the technical field of vehicle brake parts, and particularly discloses a preparation method of a carbon ceramic material brake disc resistant to high-temperature oxidation working conditions, which comprises the following steps: S1, preparing a carbon fiber preform; S2, gas phase deposition: performing chemical gas phase deposition densification on the carbon fiber preform obtained in S1 to obtain a carbon / carbon composite material blank; S3, graphitization treatment: performing graphitization treatment on the carbon / carbon composite material blank obtained in S2; S4, silicon infiltration: performing molten silicon infiltration treatment on the carbon / carbon composite material blank after the graphitization treatment by adopting an embedding method; S5, processing and shaping: performing ultrasonic shaping processing on the carbon ceramic composite material blank obtained in S4; and S6, surface oxidation resistance: coating an oxidation-resistant coating on the non-friction surface of the carbon ceramic brake disc body obtained in S5, and obtaining a carbon ceramic material brake disc finished product after solidification. The method is stable and operable, the prepared product has excellent performance, and is suitable for the fields of tanks, heavy trucks, high-speed rails, racing cars and the like which have strict requirements on braking performance.

Description

Technical Field

[0001] This invention relates to the field of vehicle braking components technology, specifically to a method for preparing a carbon ceramic brake disc resistant to high-temperature oxidation conditions. Background Technology

[0002] Carbon-ceramic composites (C / C-SiC) have become important candidate materials for brake discs in next-generation vehicles such as automobiles, high-speed trains, aircraft, and tanks due to their low density, high temperature resistance, wear resistance, and excellent braking performance. Currently, the main manufacturing processes for carbon-ceramic brake discs include chemical vapor infiltration / deposition (CVI / CVD), precursor impregnation pyrolysis (PIP), liquid phase / fused silica infiltration (RMI / LSI), and combinations thereof.

[0003] In the prior art, Chinese patent CN115773321B discloses a high-strength carbon / ceramic brake disc with a ceramic functional layer and its preparation method. This scheme uses a binary carbon matrix carbon / carbon preform: first, pyrolytic carbon is deposited on the surface of a carbon fiber preform using a CVD process; then, resin carbon or pitch carbon is filled into the pores using an impregnation carbonization process; after high-temperature graphitization, a carbon / ceramic brake disc preform is prepared through a liquid-phase silicon infiltration reaction; finally, a ceramic functional layer is formed by an in-situ reaction of a ceramic precursor adhesive on the preform surface. This technical scheme utilizes pyrolytic carbon to protect the carbon fibers and resin carbon / pitch carbon to provide the reaction carbon source, which to some extent reduces the residual silicon ratio and improves the mechanical strength and oxidation resistance of the brake disc. However, this technology still has the following problems in practical application and further performance improvement: 1. Poor matching of the binary matrix process, easily causing fiber damage: This scheme uses a binary matrix of "CVD pyrolytic carbon + impregnated resin carbon". During subsequent high-temperature silicon infiltration, although pyrolytic carbon can theoretically protect the fibers, the uneven pore structure generated by resin carbon pyrolysis makes the silicon liquid infiltration path uncontrollable. In practice, the silicon liquid will still contact and erode the carbon fibers through the microcracks generated by resin carbon pyrolysis, causing a decrease in fiber strength. In addition, the impregnation and carbonization of resin carbon / asphalt carbon requires multiple cycles, each accompanied by high-temperature treatment, resulting in cumulative thermal damage to the fibers. 2. Machining before silicon infiltration is prone to material damage: This scheme uses traditional machining to shape the low-density carbon / carbon blank before silicon infiltration. Since the blank density is low and the strength is insufficient at this time, the cutting force generated by traditional machining is prone to causing edge chipping, fiber pull-out, and surface microcracks. These machining defects are permanently solidified in the subsequent high-temperature silicon infiltration process, becoming weak links of the brake disc, which are prone to evolving into fatigue cracks during service, affecting service life and safety. 3. Lack of anti-oxidation protection for non-friction surfaces: This scheme only prepares a ceramic functional layer on the surface of the brake disc, but non-friction surfaces such as ventilation ribs, mounting surfaces, and inner cavities are also exposed to an oxidizing atmosphere during high-temperature braking. Due to the limited thickness of the ceramic functional layer and the difference in thermal expansion coefficients between it and the substrate, the coating on non-friction surfaces is prone to peeling after long-term use, leading to carbon oxidation and weight loss in the substrate, resulting in strength reduction. 4. In-situ reaction shrinkage and cracking of the surface ceramic functional layer: This solution generates a SiC layer in situ through high-temperature pyrolysis after brushing on the ceramic precursor adhesive. The adhesive undergoes significant volume shrinkage during drying and pyrolysis, easily generating penetrating microcracks and failing to form a dense protective layer. These cracks become the starting point for oxygen erosion and wear, reducing the brake disc's oxidation resistance and wear life. Furthermore, existing powder metallurgy brake discs / pads often experience serious malfunctions during use due to excessively high temperatures, leading to decreased braking friction performance and jamming. In addition, the small brake chamber space and poor ventilation and heat dissipation conditions in tanks, combined with continuous braking in mountainous environments, cause the brake chamber temperature to remain between 650℃ and 800℃ for extended periods due to temperature accumulation.Under such conditions, even if existing carbon-carbon or carbon-ceramic composite brake materials are used, such as the high-strength carbon / ceramic brake disc with a ceramic functional layer disclosed in CN115773321B, the wear of the brake disc / pad will increase due to oxidation, and the brake life requirements cannot be met.

[0004] Therefore, developing a novel carbon-ceramic brake disc with minimal fiber damage, high processing precision, excellent oxidation resistance under continuous high-temperature aerobic conditions, strong continuous braking overload capacity, wear resistance, and long service life, as well as its preparation method, has significant engineering application value. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing a carbon-ceramic brake disc resistant to high-temperature oxidation conditions. This method can effectively protect the strength of carbon fibers, avoid processing damage, improve the mechanical properties, friction and wear resistance, and oxidation resistance of the brake disc, and extend its service life.

[0006] To address the above problems, this invention provides a method for preparing a carbon-ceramic brake disc resistant to high-temperature oxidation conditions, comprising the following steps: S1 Preparation of carbon fiber preforms: Alternating layers of non-woven fabric and carbon fiber mesh are needle-punched to obtain a density of 0.45~0.50 g / cm³. 3 Carbon fiber preforms; S2 Chemical Vapor Deposition: The carbon fiber preform obtained in S1 was densified by chemical vapor deposition to obtain a density of 1.25~1.40 g / cm³. 3 Carbon / carbon composite preform; S3 graphitization treatment: The carbon / carbon composite material blank obtained in S2 is graphitized at a temperature of 2200℃~2400℃; S4 silicon infiltration: At a temperature of 1450℃~1600℃, a graphitized carbon / carbon composite material blank is subjected to melt silicon infiltration treatment using an embedding method to obtain a carbon-ceramic composite material blank; the powder used in the embedding method includes silicon powder and silicon carbide powder. S5 Processing and Shaping: The carbon-ceramic composite material blank obtained in S4 is screened to achieve a density of 2.25 g / cm³. 3 The above carbon-ceramic composite material blanks are subjected to ultrasonic forming to obtain the carbon-ceramic brake disc body; S6 Surface Anti-oxidation: The non-friction surface of the carbon ceramic brake disc body obtained in S5 is coated with an anti-oxidation coating, and after curing, the finished carbon ceramic brake disc is obtained.

[0007] Furthermore, in S1, both the non-woven fabric and the carbon fiber mesh are made of T300 / 24K PAN-based carbon fiber; the volume content of the non-woven fabric is 40%, and the volume content of the carbon fiber mesh is 60%.

[0008] Furthermore, in S2, the process of densifying the carbon fiber preform obtained in S1 by chemical vapor deposition specifically includes: S21. Cut the carbon fiber preform according to the specifications of the target brake disc. Stack the cut carbon fiber preform vertically in a vapor deposition furnace. Control the height of the stacked column to be 1.3~1.5m. Separate adjacent preforms with graphite sealing rings. Perform the first vacuum heat treatment at a furnace pressure of 1~3KPa and a temperature of 1100℃ for 4 hours. S22. After the first vacuum heat treatment, in the same vapor deposition furnace, at a furnace pressure of 1~3 kPa and a temperature of 980℃~1050℃, a first vapor deposition is carried out using natural gas, methane, or propane as the carbon source gas for 80~120 hours, so that the density of the green body reaches 0.9~1.15 g / cm³. 3 ; S23. After the first vapor deposition, the billet is taken out of the furnace and subjected to a second vacuum heat treatment at 1800℃~2000℃ for 4 hours. S24. After the second vacuum heat treatment, the billet is machined to remove the dense surface layer. S25. The machined billet is then loaded back into the vapor deposition furnace. The height of the stacked billets is controlled to not exceed 1.2~1.5m, and adjacent billets are separated by graphite sealing rings. A second vapor deposition is performed at a furnace temperature of 950℃~970℃ and a furnace pressure of 1~3KPa for 250h~350h, until the billet density reaches 1.25~1.40g / cm³. 3 .

[0009] Furthermore, in S3, the graphitization process is carried out in a vacuum heat treatment furnace for 4 hours at a furnace pressure of 1-3 kPa.

[0010] Furthermore, in S4, before the fused silicon infiltration process, the graphitized carbon / carbon composite material blank is subjected to ultrasonic processing, ultrasonic cleaning, and drying; the ultrasonic processing is used to remove the dense surface layer and open the pores.

[0011] Further, in S4, the mass ratio of silicon powder to silicon carbide powder is 1:3; the purity of the silicon powder is >95%, and the particle size is 800~1000 mesh; the particle size of the silicon carbide powder is 300~500 mesh.

[0012] Furthermore, in S4, the molten silicon infiltration process is carried out in a silicon infiltration furnace with a furnace pressure of 1~3 kPa and a holding time of 2~4 h.

[0013] Furthermore, in S5, the ultrasonic forming process includes processing the inner diameter, outer diameter, thickness, and ventilation holes.

[0014] Furthermore, in S6, the antioxidant coating is a phosphate coating; after coating, it is placed in a curing oven and cured at 300°C and 1~3KPa for 2 hours.

[0015] This invention also protects carbon-ceramic brake discs prepared by any of the above-described methods, wherein the density of the carbon-ceramic brake disc is ≥2.25 g / cm³. 3 Its non-friction surface has a phosphate antioxidant coating.

[0016] Compared with the prior art, the present invention has the following significant advantages: 1. Excellent oxidation resistance under sustained high temperature conditions: The brake disc of this invention maintains stable physicochemical properties in a sustained high-temperature aerobic environment of 650℃~800℃. ≥2.25g / cm³ 3 The high-density matrix effectively blocks oxygen permeation; the high volume ratio SiC ceramic phase endows the matrix with intrinsic oxidation resistance; and the phosphate coating provides additional protection for non-friction surfaces. Furthermore, the single CVD pyrolytic carbon matrix completely encapsulates the carbon fibers, avoiding the erosion and damage to the fibers caused by molten silicon infiltration. Moreover, this invention moves the final forming process to after silicon infiltration, employing ultrasonic one-step forming to avoid fiber pull-out and surface microcracks caused by traditional machining. These microscopic defects are the initiation source of high-temperature oxidation and thermal fatigue cracks; this solution eliminates these weak points at the source, further improving the reliability of the brake disc under high-temperature service conditions.

[0017] 2. Significantly improves the mechanical strength and reliability of brake discs: This invention uses a single CVD pyrolytic carbon matrix, meaning the entire matrix carbon is composed of chemical vapor deposition pyrolytic carbon. This avoids the thermal damage and chemical erosion of carbon fibers caused by resin / asphalt carbon impregnation and carbonization, resulting in higher strength retention of the carbon fibers. Simultaneously, the combination of two CVD deposition processes and intermediate heat treatment to open pores creates a uniform and controllable pore structure, providing an ideal channel for subsequent silicon infiltration.

[0018] 3. Completely solves processing damage problems and improves yield: This solution uses ultrasonic processing before and after siliconizing. Before siliconizing, ultrasonic processing removes the dense surface layer non-destructively, opening the siliconizing channels and avoiding fiber pull-out and micro-cracks caused by traditional machining. After siliconizing, ultrasonic processing is used for final precision shaping, machining the inner diameter, outer diameter, thickness, and ventilation holes in one step, eliminating the need for secondary cleaning. Through the synergistic optimization of ultrasonic processing and process allocation, the industry problem of easy damage to low-density carbon / bulk before siliconizing is completely solved, significantly improving the product yield.

[0019] 4. Zoned protection design for extended service life: This invention applies a phosphate anti-oxidation coating separately to non-friction surfaces, forming a zoned protection with the friction surfaces. After curing at 300℃, this coating bonds well to the substrate and effectively blocks the erosion of the substrate carbon by high-temperature oxidizing gases.

[0020] 5. Wide process window, suitable for industrial production: This solution only requires control of CVD deposition density and furnace loading method, without the need for precise matching of the ratio of pyrolytic carbon to resin carbon, resulting in good process robustness. Furthermore, ultrasonic processing and coating treatment are mature technologies, easily enabling automated mass production.

[0021] 6. Excellent overall performance, meeting extreme working conditions: The carbon-ceramic brake disc produced by this method has a density ≥2.25g / cm³. 3 With a stable coefficient of friction, it is not only suitable for conventional cars and high-speed trains, but also meets the requirements for use in tanks, heavy trucks and other vehicles with extremely high braking energy and in harsh environments. Attached Figure Description

[0022] Figure 1 This is a process flow diagram of the preparation method of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 S1 Preparation of carbon fiber preforms A traditional process for preparing carbon fiber preforms was used to prepare low-density integral carbon fiber needle-punched felt preforms. The non-woven fabric and the reinforcing mesh were made of T300 / 24K PAN-based carbon fiber, with the non-woven fabric comprising 40% and the reinforcing mesh comprising 60% by volume. Each unit structure consisted of one layer of non-woven fabric and one layer of reinforcing mesh, needle-punched together. Based on the specifications and needle-punching requirements of the carbon fiber preform, the unit structure layers were stacked together and needle-punched to achieve the specified thickness and density, ultimately resulting in a carbon fiber preform density of 0.45~0.50 g / cm³. 3 .

[0025] S2 vapor deposition A traditional carbon-carbon composite brake disc vapor deposition carburizing process was used to carburize and densify low-density carbon fiber preforms, resulting in a density of 1.25~1.40 g / cm³. 3 Carbon / carbon composite preform.

[0026] The preparation process of carbon / carbon composite preforms is as follows: ① The preform is cut into rings according to the specifications of the tank carbon-ceramic brake disc and placed into the vapor deposition furnace. The rings of the preform are separated by graphite sealing rings. The height of the material column is controlled between 1.3m and 1.5m to ensure the airtightness of the material column cavity so that a certain pressure difference can be formed inside and outside the material column during the deposition process, and the carbon source gas can be used for directional permeation flow.

[0027] ② The carbon preforms loaded into the furnace are subjected to vacuum heat treatment at a temperature of 1100℃ and a furnace pressure of 1~3KPa for 4 hours. The purpose of the heat treatment is to remove impurities from the preforms and increase the surface activation energy of the carbon fibers, so as to facilitate their bonding with deposited carbon.

[0028] ③ Perform vapor deposition on the heat-treated carbon preform, controlling the deposition temperature between 980℃ and 1050℃, the furnace pressure between 1 and 3 kPa, and using natural gas, methane, or propane as the chemical reaction gas source. Deposition time is 80 to 120 hours, achieving a density of 0.9 to 1.15 g / cm³. 3 .

[0029] ④ The carbon blank, after pre-deposition and densification, is removed from the furnace and subjected to a second vacuum heat treatment as required, followed by machining. The second vacuum heat treatment is performed at 1800℃~2000℃ for 4 hours, then machined as required. The purpose is to: deform the carbon blank through heat treatment to open up the internal pores of the material; and to remove the dense layer on the surface of the carbon blank through machining, opening up airflow channels in the pores to facilitate subsequent densification.

[0030] ⑤ The carbon blanks, after the second vacuum heat treatment and machining, are then loaded back into the vapor deposition furnace, separated by graphite sealing rings. The height of the carbon column should not exceed 1.2~1.5m. Preferably, natural gas, methane, or propane is used as the chemical reaction gas source, the furnace temperature is 950℃~970℃, the furnace pressure is 1~3KPa, the vapor deposition time is 250h~350h, and the density is increased to 1.25~1.40g / cm³. 3 .

[0031] The second-stage vapor deposition uses a lower temperature regime to effectively control the densification rate and improve the uniformity of material density and the consistency of carbon preform quality. The low-density requirement of the preform before silicon infiltration aims to lay the foundation for preparing high-density carbon-ceramic composite brake materials with a high volumetric silicon carbide content.

[0032] S3 graphitization treatment The carbon / carbon composite blank was subjected to graphitization high-temperature heat treatment to improve the graphitization degree of the carbon blank.

[0033] The above deposits were densified to 1.25~1.40 g / cm³. 3The carbon / carbon composite blank of high density is loaded into a vacuum heat treatment furnace for heat treatment. Preferably, the furnace temperature is controlled between 2200℃ and 2400℃, held for 4 hours, and the furnace pressure is 1~3 kPa.

[0034] The purpose of graphitization vacuum heat treatment is to convert as much of the deposited carbon as possible into graphitic carbon, which is conducive to the full chemical reaction during silicon infiltration and increases the volume ratio of silicon carbide.

[0035] S4 Silicon Infiltration A high-density carbon-ceramic composite material blank with a high silicon carbide volume ratio was prepared by molten silicon infiltration to densify a graphitized carbon / carbon composite material blank.

[0036] The preparation process of carbon-ceramic composite material blanks is as follows: ① The graphitized carbon / carbon composite material blanks were machined as required using ultrasonic machining. The purpose was twofold: first, to eliminate the dense carbon deposits on the surface of the low-density carbon blanks and open the pores to facilitate silicon infiltration; second, ultrasonic machining involves low tool resistance, minimal workpiece deformation, and no damage to the carbon blank matrix material during processing, with no carbon fiber pull-out.

[0037] ②The carbon blanks after machining are cleaned by ultrasonic cleaning. The purpose is to clean the carbon powder squeezed into the pores of the carbon blank material during machining, so as to improve the quality of subsequent silicon diffusion.

[0038] ③ The carbon blank is dried and then placed in a crucible containing a mixture of silicon powder and silicon carbide powder. The silicon powder and silicon carbide powder are mixed in a 1:3 ratio, using silicon powder with a purity >95% and a mesh size of 800~1000 and silicon carbide powder with a mesh size of 300~500.

[0039] ④ Place the crucible containing the low-density carbon blank into the silicon infiltration furnace, heat it to 1450~1600℃, hold it for 2~4 hours, and control the furnace pressure at 1~3KPa.

[0040] ⑤ The silicon-infiltrated carbon blank is taken out of the furnace, and the density of the carbon ceramic brake disc blank is tested. The density reaches 2.25 g / cm³. 3 The carbon-ceramic composite material blanks mentioned above are transferred to the next process. The remaining blanks can be siliconized again, and the siliconization process is the same as above.

[0041] S5 machining and forming The carbon-ceramic composite material blank that meets the silicon infiltration requirements is formed and processed according to the product drawings to obtain the carbon-ceramic brake disc body. Ultrasonic processing is preferably used.

[0042] S6 Surface Antioxidant The carbon-ceramic brake disc body, after being processed and shaped, is coated with an anti-oxidation coating on the non-friction surface of the brake disc according to product requirements. The coating is a phosphate anti-oxidation coating. After coating, the coating is cured at a temperature of 300℃, a furnace pressure of 1~3KPa, and a holding time of 2h to obtain the finished carbon-ceramic brake disc.

[0043] Comparative Example 1: Preparation of carbon fiber preforms A monolithic carbon fiber needle-punched felt preform was prepared using traditional methods for preparing carbon fiber preforms. The carbon-carbon preform had a density of 0.6 g / cm³. 3 The non-woven fabric and the mesh are made of T300 / 24K PAN-based carbon fiber. The unit structure consists of one layer of non-woven fabric and one layer of mesh, needle-punched together. The non-woven fabric content is 40%, and the mesh volume content is 60%. According to the specifications and needle-punching requirements of the carbon-carbon preform, the unit structure layers are stacked together and needle-punched to achieve the specified thickness and density.

[0044] Preparation of low-density carbon-carbon composite vapor-deposited carbon preforms The traditional carbon-carbon composite brake disc vapor deposition carburizing process is used to densify the low-density carbon fiber preform. The density of the low-density carbon-carbon preform before siliconization should be controlled at 1.45~1.55 g / cm³. 3 between.

[0045] The preparation process of low-density carbon preforms is as follows: ① Cut the preform into rings according to the specifications of the carbon-ceramic brake disc and load them into the vapor deposition furnace. Separate the preform rings with graphite sealing rings. Control the height of the material column between 1.3m and 1.5m to ensure the airtightness of the material column cavity so that a certain pressure difference can be formed inside and outside the material column during the deposition process, utilizing the directional permeation flow of carbon source gas.

[0046] ② The carbon preforms loaded into the furnace are subjected to vacuum heat treatment at a temperature of 1100℃ and a furnace pressure of 1~3KPa for 4 hours. The purpose of the heat treatment is to remove impurities from the preforms and increase the surface activation energy of the carbon fibers, so as to facilitate their bonding with deposited carbon.

[0047] ③ Perform vapor deposition on the heat-treated carbon preform, controlling the deposition temperature between 980℃ and 1050℃, the furnace pressure between 1 and 3 kPa, and using natural gas, methane, or propane as the chemical reaction gas source. Deposition time is 80 to 120 hours, achieving a density of 0.9 to 1.15 g / cm³. 3 .

[0048] ④ The carbon blanks that have been pre-deposited and densified are taken out of the furnace, subjected to a second vacuum heat treatment as required, and then taken out of the furnace and machined.

[0049] The second vacuum heat treatment is performed at a temperature of 1800℃~2000℃ for 4 hours. After that, the product is removed from the furnace and machined as required.

[0050] ⑤ The carbon blanks, after the second vacuum heat treatment and machining, are then loaded back into the vapor deposition furnace, separated by graphite sealing rings. The height of the carbon column should not exceed 1.2~1.5m. Preferably, natural gas, methane, or propane is used as the chemical reaction gas source, the furnace temperature is 950℃~970℃, the furnace pressure is 1~3KPa, the vapor deposition time is 250h~350h, and the density is increased to 1.45~1.55g / cm³. 3 .

[0051] C Low-density carbon blank graphitization treatment A second vacuum high-temperature heat treatment was performed on the low-density carbon blank to improve its graphitization degree. This densified the deposit to 1.45–1.55 g / cm³. 3 The carbon blanks of high density are loaded into a vacuum heat treatment furnace for heat treatment. Preferably, the furnace temperature is controlled between 2200℃ and 2400℃, held for 4 hours, and the furnace pressure is 1~3 kPa.

[0052] D Low-density carbon-carbon composite brake material blank processing and forming The above-mentioned deposits were densified to 1.45~1.55 g / cm³ using traditional machining methods. 3 The carbon-ceramic blank is machined to form the main components. Because carbon ceramic material is quite hard, conventional machining methods are difficult and inefficient. Therefore, the final forming process is performed before siliconizing.

[0053] Preparation of E-carbon ceramic composite brake material blank A carbon-ceramic composite brake material with high density and high silicon carbide volume ratio was prepared by using an embedding silicon infiltration process to molten silicon infiltrate and densify a low-density carbon blank that had undergone graphitization treatment.

[0054] The preparation process of carbon ceramic blanks is as follows: ① The carbon blank after machining is cleaned by ultrasonic cleaning method. The purpose is to clean the carbon powder squeezed into the surface pores of the carbon blank material during machining, so as to improve the quality of subsequent silicon diffusion.

[0055] ② The carbon blank is dried and then placed in a crucible containing a mixture of silicon powder and silicon carbide powder. The silicon powder and silicon carbide powder are mixed in a 1:3 ratio, using silicon powder with a purity >95% and a mesh size of 800~1000 and silicon carbide powder with a mesh size of 300~500.

[0056] ③ Place the crucible containing the low-density carbon blank into the silicon infiltration furnace, heat it to 1450~1600℃, hold it for 2~4 hours, and control the furnace pressure at 1~3KPa.

[0057] ④ The silicon-infiltrated carbon blank is removed from the furnace, and the density of the carbon-ceramic brake disc blank is tested. The density should reach 1.85~2.05 g / cm³. 3 The carbon-ceramic brake disc blanks are transferred to the next process, and the remaining blanks can be siliconized again, with the siliconizing process being the same as above.

[0058] ⑤ The carbon-ceramic brake discs that meet the requirements for silicon infiltration and densification are subjected to final vacuum heat treatment at a temperature of 1750℃~1850℃, a furnace pressure of 1~3KPa, and a holding time of 4h. The purpose of the final heat treatment is twofold: first, to reduce excess residual silicon in the brake disc material, controlling the residual silicon to ≤4%; and second, to eliminate residual stress within the material.

[0059] ⑥ Perform final finishing on the carbon-ceramic brake discs after final heat treatment to ensure the shape and dimensional accuracy requirements of the brake discs. Because excess silicon and silicon carbide residue remains on some surfaces of the formed carbon blanks after siliconizing and heat treatment due to thermal deformation and siliconizing processes, this affects both the surface quality of the brake discs and the dimensional accuracy of the product.

[0060] F-type carbon ceramic brake discs undergo anti-oxidation treatment on non-friction surfaces. The carbon-ceramic brake disc, after being processed and shaped, is coated with an anti-oxidation coating on its non-friction surface according to product requirements. The coating is a phosphate anti-oxidation coating, which is then cured at 300℃ and 1-3 kPa for 2 hours. At this point, the carbon-ceramic brake disc is complete.

[0061] The carbon-ceramic brake disc for tanks prepared in the embodiments of the present invention is compared with the carbon-ceramic brake disc prepared in the comparative example. The results are shown in Table 1: Table 1. Performance Comparison of Examples and Comparative Examples <![CDATA[density (g / cm 3 )]]> ≥2.25 1.85~2.05 Pre-siliconizing processing methods Ultrasonic machining (hole opening only) Traditional machining (final forming) Post-siliconizing processing Ultrasonic one-time forming Supplemental refining Processing defects (fiber pull-out / edge chipping) none There is obvious processing damage Non-friction surface coating Phosphate coating Phosphate coating As can be seen from the above comparison, the present invention has the following essential differences and significant technical advantages compared with the comparative example: 1. Different process routes result in less processing damage: In the comparative example, the final shaping process is arranged before silicon infiltration, and traditional machining is used for low-density carbon blanks of 1.45~1.55 g / cm³. 3Traditional forming processes, due to the low strength of the blank and high cutting resistance, are prone to material damage and carbon fiber pull-out during machining. This damage is permanently solidified during the subsequent silicon infiltration process, becoming a weak point in the brake disc. This invention moves the final forming process to after silicon infiltration, and both pre- and post-silicon infiltration processes utilize ultrasonic machining. Before silicon infiltration, only a light ultrasonic machining process is performed to remove the dense surface layer and open the pores; no final forming is performed. After silicon infiltration, ultrasonic machining is used for a single forming process. Ultrasonic machining involves low tool resistance and minimal workpiece deformation, ensuring no damage to the base material and no carbon fiber pull-out during processing, fundamentally avoiding the damage problems of traditional machining.

[0062] 2. Lower density of the pre-siliconizing blank, resulting in more complete siliconization: The density of the carbon pre-siliconizing blank in this invention is controlled at 1.25~1.40 g / cm³. 3 It is lower than the comparative example of 1.45~1.55 g / cm³. 3 Lower density means higher porosity and more unobstructed silicon diffusion channels, allowing molten silicon to penetrate the preform more fully and evenly for reaction, resulting in a final product density of 2.25 g / cm³. 3 The above values ​​are higher than the comparative example's 1.85~2.05 g / cm³. 3 Higher density directly translates into superior mechanical properties and wear resistance.

[0063] 3. Simplified process and higher production efficiency: The comparative example requires a final vacuum heat treatment at 1750℃~1850℃ after silicon infiltration to reduce residual silicon and eliminate residual stress, followed by additional finishing to ensure dimensional accuracy. This invention optimizes the process by increasing the graphitization temperature to 2200℃~2400℃, allowing the deposited carbon to be more fully converted into graphitic carbon, facilitating the subsequent silicon infiltration reaction. This eliminates the need for final heat treatment and additional finishing after silicon infiltration, simplifying the process and reducing production costs.

[0064] 4. Overall performance meets the requirements of extreme working conditions: The density of the tank carbon-ceramic brake disc prepared by this invention is ≥2.25g / cm³. 3 With sufficient silicon infiltration and a dense matrix, combined with a phosphate anti-oxidation coating on the non-friction surface, it can maintain stable friction and anti-oxidation performance in the high-temperature oxygen environment of 650℃~800℃ caused by continuous braking of tanks in mountainous terrain. It solves the problems of performance degradation, adhesion, and jamming of existing powder metallurgy brake discs under extreme conditions, and significantly improves the mobility and safety of tanks in complex mountainous environments.

[0065] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing a carbon-ceramic brake disc resistant to high-temperature oxidation conditions, characterized in that: Includes the following steps: S1 Preparation of carbon fiber preforms: Alternating layers of non-woven fabric and carbon fiber mesh are needle-punched to obtain a density of 0.45~0.50 g / cm³. 3 Carbon fiber preforms; S2 Chemical Vapor Deposition: The carbon fiber preform obtained in S1 was densified by chemical vapor deposition to obtain a density of 1.25~1.40 g / cm³. 3 Carbon / carbon composite preform; S3 graphitization treatment: The carbon / carbon composite material blank obtained in S2 is graphitized at a temperature of 2200℃~2400℃; S4 silicon infiltration: At a temperature of 1450℃~1600℃, a graphitized carbon / carbon composite material blank is subjected to melt silicon infiltration treatment using an embedding method to obtain a carbon-ceramic composite material blank; the powder used in the embedding method includes silicon powder and silicon carbide powder. S5 Processing and Shaping: The carbon-ceramic composite material blank obtained in S4 is screened to achieve a density of 2.25 g / cm³. 3 The above carbon-ceramic composite material blanks are subjected to ultrasonic forming to obtain the carbon-ceramic brake disc body; S6 Surface Anti-oxidation: The non-friction surface of the carbon ceramic brake disc body obtained in S5 is coated with an anti-oxidation coating, and after curing, the finished carbon ceramic brake disc is obtained.

2. The method for preparing a carbon ceramic brake disc resistant to high-temperature oxidation conditions according to claim 1, characterized in that: In S1, both the non-woven fabric and the carbon fiber mesh are made of T300 / 24K PAN-based carbon fiber; the volume content of the non-woven fabric is 40%, and the volume content of the carbon fiber mesh is 60%.

3. The method for preparing a carbon ceramic brake disc resistant to high-temperature oxidation conditions according to claim 1, characterized in that: In S2, the process of densifying the carbon fiber preform obtained in S1 by chemical vapor deposition specifically includes: S21. Cut the carbon fiber preform according to the specifications of the target brake disc. Stack the cut carbon fiber preform vertically in a vapor deposition furnace. Control the height of the stacked column to be 1.3~1.5m. Separate adjacent preforms with graphite sealing rings. Perform the first vacuum heat treatment at a furnace pressure of 1~3KPa and a temperature of 1100℃ for 4 hours. S22. After the first vacuum heat treatment, in the same vapor deposition furnace, at a furnace pressure of 1~3 kPa and a temperature of 980℃~1050℃, a first vapor deposition is carried out using natural gas, methane, or propane as the carbon source gas for 80~120 hours, so that the density of the green body reaches 0.9~1.15 g / cm³. 3 ; S23. After the first vapor deposition, the billet is taken out of the furnace and subjected to a second vacuum heat treatment at 1800℃~2000℃ for 4 hours. S24. After the second vacuum heat treatment, the billet is machined to remove the dense surface layer. S25. The machined billet is then loaded back into the vapor deposition furnace. The height of the stacked billets is controlled to not exceed 1.2~1.5m, and adjacent billets are separated by graphite sealing rings. A second vapor deposition is performed at a furnace temperature of 950℃~970℃ and a furnace pressure of 1~3KPa for 250h~350h, until the billet density reaches 1.25~1.40g / cm³. 3 .

4. The method for preparing a carbon ceramic brake disc resistant to high-temperature oxidation conditions according to claim 1, characterized in that: In S3, the graphitization process is carried out in a vacuum heat treatment furnace for 4 hours at a furnace pressure of 1-3 kPa.

5. The method for preparing a carbon ceramic brake disc resistant to high-temperature oxidation conditions according to claim 1, characterized in that: In step S4, prior to the fused silicon infiltration process, the carbon / carbon composite material blank after graphitization is subjected to ultrasonic processing, ultrasonic cleaning, and drying; the ultrasonic processing is used to remove the dense surface layer and open the pores.

6. The method for preparing a carbon ceramic brake disc resistant to high-temperature oxidation conditions according to claim 1, characterized in that: In S4, the mass ratio of silicon powder to silicon carbide powder is 1:3; the purity of the silicon powder is >95% and the particle size is 800~1000 mesh; the particle size of the silicon carbide powder is 300~500 mesh.

7. The method for preparing a carbon ceramic brake disc resistant to high-temperature oxidation conditions according to claim 1, characterized in that: In S4, the molten silicon infiltration process is carried out in a silicon infiltration furnace with a furnace pressure of 1~3 kPa and a holding time of 2~4 h.

8. The method for preparing a carbon ceramic brake disc resistant to high-temperature oxidation conditions according to claim 1, characterized in that: In S5, the ultrasonic forming process includes processing the inner diameter, outer diameter, thickness, and ventilation holes.

9. The method for preparing a carbon ceramic brake disc resistant to high-temperature oxidation conditions according to claim 1, characterized in that: In S6, the antioxidant coating is a phosphate coating; after coating, it is placed in a curing oven and cured at 300°C and 1~3KPa for 2 hours.

10. A carbon-ceramic brake disc prepared by the method according to any one of claims 1 to 9, characterized in that: The density of the carbon-ceramic brake disc is ≥2.25 g / cm³. 3 Its non-friction surface has a phosphate antioxidant coating.

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