Technology for enhancing cohesiveness of carbon-carbon matrix and SiC ceramic powder coating

Abstract

The invention relates to a technology for enhancing the cohesiveness of a carbon-carbon matrix and a SiC ceramic powder coating, and relates to the technical field of high-end brake materials, and the specific bonding steps are as follows: taking a carbon fiber preform plate as a raw material, placing in an isothermal chemical vapor deposition furnace, depositing for 150-200 hours at 1000-1100 DEG C and normal pressure, and increasing the density to 1.3 g / cm < 3 > to obtain a carbon / carbon composite material blank; according to the technology for enhancing the cohesiveness of the carbon-carbon matrix and the SiC ceramic powder coating, coating preparation is completed through three steps of CNC mechanical slotting, phenolic resin-SiC powder hot pressing and primary fusion siliconizing, and laser / plasma surface modification or 1-5 [mu] m isotropic carbon transition layer deposition needed in the prior art is completely replaced; equipment is simplified from a laser / plasma or high-temperature CVD (Chemical Vapor Deposition) system to a conventional CNC (Computer Numerical Control), a hot press and a siliconizing furnace, and the investment of a single production line is reduced by more than 30%; the production period is shortened from 7-10 days to 2-3 days, manpower and energy consumption are synchronously reduced, the unit cost is reduced by 25%-40%, and low-cost and large-scale industrial production is truly achieved.

Description

Technical Field

[0001] This invention relates to the field of high-end braking materials technology, specifically to a technology for enhancing the adhesion between a carbon matrix and a SiC ceramic powder coating. Background Technology

[0002] Carbon-carbon composites (C / C composites) have been widely used in aerospace, automotive braking systems and other fields due to their excellent high-temperature performance and mechanical strength. However, C / C composites are prone to oxidation under high-temperature conditions and have unstable friction coefficients under wet conditions, which prevents their large-scale application in the passenger car field. In particular, when preparing high-performance carbon-ceramic brake discs, it is necessary to form a silicon carbide (SiC) ceramic coating with high wear resistance and heat resistance on the C / C matrix to improve the overall performance. The coating not only protects the matrix, but also significantly improves the friction coefficient, reduces the wear rate, and improves thermal conductivity and oxidation resistance.

[0003] Currently, there are two main approaches in the industry for preparing SiC coatings on C / C composite surfaces:

[0004] First, direct coating after surface modification—the C / C surface is roughened by means of laser, plasma or acid pickling, and then a SiC layer is deposited by slurry coating or chemical vapor deposition (CVD).

[0005] Second, the interface transition layer technology—first, isotropic carbon of 1–5 μm is epitaxially grown on the C / C surface using chemical vapor deposition (CVD) as a buffer layer, and then SiC is deposited on this transition layer.

[0006] Both of the above technologies can improve the interfacial bonding strength between C / C and SiC to a certain extent, and are widely used in existing patents and production practices.

[0007] However, with the significant increase in the production of carbon ceramic brake discs in passenger vehicles, the aforementioned traditional coating technologies have revealed obvious shortcomings:

[0008] Firstly, surface modification processes require laser, plasma, or strong acid equipment, which involve high investment, heavy environmental impact, and difficulty in ensuring batch uniformity.

[0009] Secondly, the interface transition layer technology requires the additional deposition of 1–5 μm of isotropic carbon, which results in long deposition time and a narrow process window, leading to an extended overall production cycle and high costs.

[0010] Third, C / C(1–3×10 -6 / ℃) and SiC (4.5×10 -6The difference in thermal expansion coefficients (°C) remains significant. Existing technologies lack low-cost, high-efficiency structural compensation methods, resulting in coating cracking and peeling after thermal cycling, making it difficult to meet the industrial requirements for long-life, high-reliability brake discs. Summary of the Invention

[0011] To address the shortcomings of existing technologies, this invention provides a technique for enhancing the adhesion between a carbon-carbon substrate and a SiC ceramic powder coating. This technique features the advantages of mechanically machining grooves on the surface of the carbon-carbon substrate and combining them with a hot-pressing-siliconizing process. This significantly enhances the mechanical bonding and interfacial adhesion strength between the SiC ceramic coating and the substrate, and solves the problems of easy detachment and poor adhesion of traditional coatings caused by the difference in their thermal expansion coefficients.

[0012] To achieve the above objectives, the present invention provides the following technical solution: a technology to enhance the adhesion between a carbon-carbon matrix and a SiC ceramic powder coating, wherein the specific bonding steps are as follows:

[0013] S1. Using carbon fiber preforms as raw material, deposit them in an isothermal chemical vapor deposition furnace at 1000–1100℃ and atmospheric pressure for 150–200 hours to increase the density to 1.3 g / cm³. 3 A carbon / carbon composite preform was obtained;

[0014] S2. The billet from step S1 is transferred into a vacuum high-temperature furnace, vacuumed to ≤10Pa, heated to 2000℃, held for 2–4 hours for high-temperature heat treatment, and then cooled with the furnace.

[0015] S3. On a CNC machining center, use a diamond end mill to machine parallel grooves 3mm wide, 1.5mm deep, and 2–4mm apart on the surface of the blank.

[0016] S4. Weigh phenolic resin powder (≤75μm) and SiC powder (≤50μm) at a mass ratio of 35:65, place them in a ball mill and mix for ≥30min until the color is uniform;

[0017] S5. Fill the groove with the mixed powder and cover the surface. After molding, heat the mixture to 180°C in a hot press and apply a pressure of 10–15 MPa. Hold the pressure for 20–30 minutes to produce carbon-carbon composite material / resin-SiC composite sheet.

[0018] S6. Place the composite wafer into the silicon infiltration furnace, adding 20% ​​excess silicon material as required by theory. Evacuate the furnace to ≤10 Pa, raise the temperature to 1500–1700℃, and hold for 2–3 hours for melt silicon infiltration. The density after removing from the furnace should reach 2.1–2.3 g / cm³. 3 ;

[0019] S7. Use 120–200 grit and 400–600 grit diamond grinding wheels for rough and fine grinding respectively. Each rough grinding pass is 0.1 mm and each fine grinding pass is 0.02 mm, until the dimensional tolerance is ±0.05 mm and the surface roughness Ra≤0.8 μm.

[0020] S8. Perform shear bond strength test (≥35MPa) and micro / visual inspection on the finished product (coating integrity rate ≥98%) to confirm that SiC in the groove is completely fused with the substrate and there are no peeling defects.

[0021] Furthermore, in step S1, the carbon source gas for isothermal chemical vapor deposition is a mixture of propylene and natural gas in a volume ratio of 2:1, with a flow rate controlled at 1.5–2.0 L / min, and the temperature gradient inside the furnace during deposition is ≤5℃ / cm.

[0022] Furthermore, in step S2, the vacuum high-temperature heat treatment stage, the temperature is first raised to 1500℃ at a rate of 5℃ / min, and then raised to 2000℃ at a rate of 3℃ / min. During the cooling stage, argon gas with a purity of ≥99.999% is introduced to 20kPa.

[0023] Furthermore, in step S3, the groove cross-section is rectangular or inverted trapezoidal, the inverted trapezoidal sidewall inclination angle is 15°–30°, and the total area of ​​the groove accounts for 25%–35% of the surface area of ​​the blank.

[0024] Furthermore, in step S4, the ball mill speed is 150–200 rpm, the ball-to-material ratio is 3:1, and 1%–2% of anhydrous ethanol by weight of the total raw materials is added as a dispersant. The loose density of the mixed powder is ≥1.1 g / cm³. 3 .

[0025] Furthermore, the heating procedure in step S5 is to first raise the temperature to 120°C at 10°C / min and hold it for 10 minutes, then raise it to 180°C at 5°C / min, and after the pressure holding is completed, allow it to cool naturally to ≤60°C before demolding.

[0026] Furthermore, in step S6, the silicon material is a polycrystalline silicon block with a particle size of 1–5 mm, and a graphite paper with a thickness of 0.5 mm is placed between the silicon material and the composite wafer. During the silicon infiltration process, the heating rate is 8–10 °C / min, and the cooling rate is ≤5 °C / min.

[0027] Furthermore, in step S7, an ultrasonic cleaning is performed between the coarse grinding and the fine grinding, with a frequency of 40kHz, a power of 200W, and a time of 5min.

[0028] Furthermore, the shear bond strength test in step S8 adopts the ASTM-C1292 standard, with a cross-sectional speed of 0.5 mm / min, a microscopic magnification of ≥200×, and a single-point peel area of ​​≥0.5 mm². 2 That is, it is unqualified.

[0029] Furthermore, the oxygen content of the carbon / carbon composite preform, composite sheet, and final carbon-ceramic brake disc is controlled to be ≤500ppm.

[0030] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0031] 1. This technology for enhancing the adhesion between carbon-carbon matrix and SiC ceramic powder coating completes coating preparation in three steps: "CNC mechanical grooving + hot pressing of phenolic resin-SiC powder + one-time melt silicon infiltration". It completely replaces the laser / plasma surface modification or 1-5μm isotropic carbon transition layer deposition required by existing technologies. The equipment is simplified from laser / plasma or high-temperature CVD systems to conventional CNC, hot press and silicon infiltration furnace. The investment in a single production line is reduced by more than 30%; the production cycle is reduced from 7-10 days to 2-3 days, and labor and energy consumption are reduced simultaneously. The unit cost is reduced by 25%-40%, truly realizing low-cost, large-scale industrial production.

[0032] 2. This enhanced adhesion technology between the carbon-carbon matrix and the SiC ceramic powder coating utilizes a 3mm wide × 1.5mm deep groove (with an inverted trapezoidal shape, angle 15°–30°) machined into the C / C matrix. This creates a dual anchoring effect at the interface, combining mechanical interlocking and chemical bonding, effectively compensating for the difference in thermal expansion coefficients between C / C and SiC. The ASTM-C1292 shear test shows a bond strength ≥35MPa, and after 1000 cycles of thermal cycling, the coating integrity is ≥98%, with no peeling or cracking. The oxygen content is controlled at ≤500ppm throughout the process, further suppressing high-temperature oxidation failure. Compared to traditional solutions, the brake disc lifespan is more than doubled, fully meeting the stringent requirements of passenger cars and high-speed trains for highly reliable braking components. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the present invention;

[0034] Figure 2 This is a schematic diagram of the carbon-carbon composite material structure of the present invention;

[0035] Figure 3 This is a schematic diagram of the carbon-carbon composite material structure after the groove is processed according to the present invention;

[0036] Figure 4 This is a schematic diagram of the brake disc structure after pressing the coating according to the present invention;

[0037] Figure 5 This is a schematic diagram of the brake disc structure after pressing the coating according to the present invention;

[0038] Figure 6 This is a schematic diagram of the carbon ceramic brake disc structure of the present invention. Detailed Implementation

[0039] 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.

[0040] Please see Figure 1-6 The bonding technique for enhancing the adhesion between the carbon-carbon matrix and the SiC ceramic powder coating in this embodiment includes the following specific bonding steps:

[0041] S1. Using carbon fiber preforms as raw material, deposit them in an isothermal chemical vapor deposition furnace at 1000–1100℃ and atmospheric pressure for 150–200 hours to increase the density to 1.3 g / cm³. 3 A carbon / carbon composite preform was obtained;

[0042] S2. The billet from step S1 is transferred into a vacuum high-temperature furnace, vacuumed to ≤10Pa, heated to 2000℃, held for 2–4 hours for high-temperature heat treatment, and then cooled with the furnace.

[0043] S3. On a CNC machining center, use a diamond end mill to machine parallel grooves 3mm wide, 1.5mm deep, and 2–4mm apart on the surface of the blank.

[0044] S4. Weigh phenolic resin powder (≤75μm) and SiC powder (≤50μm) at a mass ratio of 35:65, place them in a ball mill and mix for ≥30min until the color is uniform;

[0045] S5. Fill the groove with the mixed powder and cover the surface. After molding, heat the mixture to 180°C in a hot press and apply a pressure of 10–15 MPa. Hold the pressure for 20–30 minutes to produce carbon-carbon composite material / resin-SiC composite sheet.

[0046] S6. Place the composite wafer into the silicon infiltration furnace, adding 20% ​​excess silicon material as required by theory. Evacuate the furnace to ≤10 Pa, raise the temperature to 1500–1700℃, and hold for 2–3 hours for melt silicon infiltration. The density after removing from the furnace should reach 2.1–2.3 g / cm³. 3 ;

[0047] S7. Use 120–200 grit and 400–600 grit diamond grinding wheels for rough and fine grinding respectively. Each rough grinding pass is 0.1 mm and each fine grinding pass is 0.02 mm, until the dimensional tolerance is ±0.05 mm and the surface roughness Ra≤0.8 μm.

[0048] S8. Perform shear bond strength test (≥35MPa) and micro / visual inspection on the finished product (coating integrity rate ≥98%) to confirm that SiC in the groove is completely fused with the substrate and there are no peeling defects.

[0049] It should be noted that by using the integrated process of "CNC mechanical grooving + hot pressing of phenolic resin-SiC powder + molten silicon infiltration", the expensive laser / plasma surface modification and 1-5μm transition carbon layer deposition are omitted, reducing equipment investment by 30% and shortening the production cycle from 7-10 days to 2-3 days, resulting in an overall cost reduction of 25%-40%. At the same time, the 3mm×1.5mm groove forms a mechanical fit, which, combined with 180℃ hot pressing and 1600-1700℃ silicon infiltration, achieves a shear bond strength of ≥35MPa and a coating integrity rate of ≥98% after 1000 cold and hot cycles. This effectively overcomes the peeling problem caused by the thermal expansion mismatch between C / C and SiC, and combines low cost, high efficiency and high reliability.

[0050] In step S1, the carbon source gas for isothermal chemical vapor deposition is a mixture of propylene and natural gas in a volume ratio of 2:1, with a flow rate controlled at 1.5–2.0 L / min, and the temperature gradient inside the furnace during deposition is ≤5℃ / cm.

[0051] It should be noted that this step uses a 2:1 mixture of propylene and natural gas as the carbon source gas, deposited at a stable flow rate of 1.5–2.0 L / min and a low temperature gradient of ≤5℃ / cm. This significantly improves carbon source utilization, shortens deposition time, and ensures uniform bulk density, thereby maintaining a bulk density of 1.3 g / cm³. 3 While achieving the target density, energy consumption and raw material costs are reduced.

[0052] In step S2, the vacuum high-temperature heat treatment stage, the temperature is first raised to 1500℃ at a rate of 5℃ / min, and then raised to 2000℃ at a rate of 3℃ / min. During the cooling stage, argon gas with a purity of ≥99.999% is introduced to 20kPa.

[0053] It should be noted that this step, through a stepwise slow heating process of "5℃ / min → 1500℃ + 3℃ / min → 2000℃" combined with a slow cooling process using high-purity argon gas pressure controlled to 20kPa, effectively suppresses thermal stress cracking and volume shrinkage of the C / C billet, ensuring a dense and uniform matrix structure. This provides a highly stable, low-defect carbon / carbon matrix for subsequent groove processing and a firm bond with the SiC coating.

[0054] In step S3, the groove cross-section is rectangular or inverted trapezoidal, the inverted trapezoidal sidewall inclination angle is 15°–30°, and the total area of ​​the groove accounts for 25%–35% of the surface area of ​​the blank.

[0055] It should be noted that this step, by designing the groove as an inverted trapezoid (or rectangle) of 15°–30° and uniformly occupying 25%–35% of the surface area of ​​the blank, significantly expands the mechanical interlocking interface between the C / C matrix and the SiC powder, and utilizes the inclination angle to release thermal expansion mismatch stress. This ensures that the shear strength remains ≥35MPa and the coating integrity ≥98% during subsequent thermal cycling, balancing high adhesion reliability with lightweight structure.

[0056] In step S4, the ball mill speed is 150–200 rpm, the ball-to-material ratio is 3:1, and 1%–2% of anhydrous ethanol is added as a dispersant. The loose density of the mixed powder is ≥1.1 g / cm³. 3 .

[0057] It should be noted that this step involves adding 1%–2% anhydrous ethanol as a dispersant under mild conditions of 150–200 rpm and a ball-to-powder ratio of 3:1, to ensure that the phenolic resin and SiC powder are uniformly refined and fully coated, achieving a loose packing density ≥1.1 g / cm³. 3 This not only improves the subsequent hot pressing filling rate and density, but also avoids excessive crushing and energy consumption, ensuring uniform coating composition, good fluidity, and fewer sintering defects.

[0058] In step S5, the heating process involves first raising the temperature to 120°C at a rate of 10°C / min and holding it for 10 minutes, then raising it to 180°C at a rate of 5°C / min. After the pressure holding is completed, the temperature is allowed to cool naturally to ≤60°C before demolding.

[0059] It should be noted that the stepped heating of "120℃ pre-curing + 180℃ final pressing" and slow cooling of ≤60℃ not only eliminates the cracking of the preform caused by thermal shock, but also ensures that the resin is fully cross-linked and the SiC powder densely fills the grooves, significantly improving dimensional accuracy and interfacial bonding strength, while extending mold life and reducing maintenance costs.

[0060] In step S6, the silicon material is a polycrystalline silicon block with a particle size of 1–5 mm. A graphite paper with a thickness of 0.5 mm is placed between the silicon material and the composite wafer. The heating rate during silicon infiltration is 8–10 °C / min, and the cooling rate is ≤5 °C / min.

[0061] It should be noted that this step uses 1–5 mm polycrystalline silicon blocks lined with 0.5 mm graphite paper, combined with rapid heating at 8–10 °C / min and slow cooling at ≤5 °C / min. This ensures continuous and uniform silicon penetration, while the graphite paper prevents sticking and reduces residual silicon adhesion, resulting in a dense silicon-infiltrated layer, shortening the cycle and reducing subsequent cleaning and processing costs.

[0062] In step S7, an ultrasonic cleaning is performed between the coarse grinding and the fine grinding, with a frequency of 40kHz, a power of 200W, and a time of 5min.

[0063] It should be noted that inserting a 40kHz, 200W, 5min ultrasonic cleaning between rough and fine grinding can efficiently remove embedded chips and free particles, ensuring that there are no secondary scratches in the subsequent fine grinding. The surface roughness is directly reduced to Ra≤0.8μm, while reducing grinding wheel wear and tool change frequency, improving processing efficiency and product consistency.

[0064] In step S8, the shear bond strength test was conducted according to ASTM-C1292 standard, with a cross-sectional speed of 0.5 mm / min, a microscopic magnification of ≥200×, and a single-point peel area of ​​≥0.5 mm². 2 That is, it is unqualified.

[0065] It should be noted that this step uses ASTM-C1292 as the testing standard, and a constant shear rate of 0.5 mm / min ensures data comparability; ≥200× microscopic magnification and "single-point peel ≥0.5 mm" are required. 2 The dual rigorous judgment of "immediate rejection" can accurately screen out interface defects, ensuring that the shear strength of the finished product is ≥35MPa and the coating integrity rate is ≥98%, which greatly improves the reliability and consistency of carbon ceramic brake discs.

[0066] The oxygen content of the carbon / carbon composite preform, composite sheet, and final carbon-ceramic brake disc is controlled to be ≤500ppm.

[0067] It should be noted that locking the oxygen content at ≤500ppm throughout the process can significantly suppress the oxidative embrittlement of the carbon matrix and SiC interface at high temperatures, avoid the generation of microcrack sources, thereby maintaining a shear strength of ≥35MPa and extending the thermal cycle life by more than double. At the same time, it simplifies the atmosphere protection requirements and reduces production costs.

[0068] In the above embodiments, this embodiment adopts an integrated route of "CNC grooving + hot pressing - silicon infiltration", with eight progressive steps: first, the preform is rapidly densified using low-gradient ICVI, then thermal stress is eliminated by stepped heating and slow cooling with high-purity argon; subsequently, the mechanical interlocking area is increased by 25-35% using inverted trapezoidal grooves (15–30°), and ≥1.1 g / cm³ is obtained by wet ball milling at 150–200 rpm. 3 Uniform powder; 180℃ hot pressing ensures full resin cross-linking and precise dimensions; then, rapid silicon infiltration at 8–10℃ / min is achieved using 1–5mm silicon blocks and graphite paper; ultrasonic cleaning is completed in one pass between coarse and fine grinding; finally, rigorous testing according to ASTM-C1292 is performed, with oxygen content ≤500ppm throughout the process. The entire process reduces equipment investment by 30%, shortens the cycle to 2–3 days, and reduces costs by 25–40%, while achieving shear bonding ≥35MPa and a coating integrity rate ≥98% after 1000 thermal cycles, combining the four major advantages of low cost, high efficiency, high reliability, and long lifespan.

[0069] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A technology for enhancing the adhesion between a carbon-carbon matrix and a SiC ceramic powder coating, characterized in that, The specific bonding steps are as follows: S1. Using carbon fiber preforms as raw material, deposit them in an isothermal chemical vapor deposition furnace at 1000–1100℃ and atmospheric pressure for 150–200 hours to increase the density to 1.3 g / cm³. 3 A carbon / carbon composite preform was obtained; S2. Transfer the billet from step S1 into a vacuum high-temperature furnace, evacuate it to ≤10Pa, heat it to 2000℃, hold it at that temperature for 2–4 hours for high-temperature heat treatment, and then cool it with the furnace. S3. On a CNC machining center, use a diamond end mill to machine parallel grooves 3mm wide, 1.5mm deep, and 2–4mm apart on the surface of the blank. S4. Weigh phenolic resin powder (≤75μm) and SiC powder (≤50μm) at a mass ratio of 35:65, place them in a ball mill and mix for ≥30min until the color is uniform; S5. Fill the groove with the mixed powder and cover the surface. After molding, heat the mixture to 180°C in a hot press and apply a pressure of 10–15 MPa. Hold the pressure for 20–30 minutes to produce carbon-carbon composite material / resin-SiC composite sheet. S6. Place the composite wafer into the silicon infiltration furnace, adding 20% ​​excess silicon material as required by theory. Evacuate the furnace to ≤10 Pa, raise the temperature to 1500–1700℃, and hold for 2–3 hours for melt silicon infiltration. The density after removing from the furnace should reach 2.1–2.3 g / cm³. 3 ; S7. Use 120–200 grit and 400–600 grit diamond grinding wheels for rough and fine grinding respectively. Each rough grinding pass is 0.1 mm and each fine grinding pass is 0.02 mm, until the dimensional tolerance is ±0.05 mm and the surface roughness Ra≤0.8 μm. S8. Perform shear bond strength test (≥35MPa) and micro / visual inspection on the finished product (coating integrity rate ≥98%) to confirm that SiC in the groove is completely fused with the substrate and there are no peeling defects.

2. The technology for enhancing the adhesion between a carbon-carbon matrix and a SiC ceramic powder coating according to claim 1, characterized in that: In step S1, the carbon source gas for isothermal chemical vapor deposition is a mixture of propylene and natural gas in a volume ratio of 2:1, with a flow rate controlled at 1.5–2.0 L / min, and the temperature gradient inside the furnace during deposition is ≤5℃ / cm.

3. The technology for enhancing the adhesion between a carbon-carbon matrix and a SiC ceramic powder coating according to claim 1, characterized in that: In step S2, the vacuum high-temperature heat treatment stage, the temperature is first raised to 1500℃ at a rate of 5℃ / min, and then raised to 2000℃ at a rate of 3℃ / min. During the cooling stage, argon gas with a purity of ≥99.999% is introduced to 20kPa.

4. The technology for enhancing the adhesion between a carbon-carbon matrix and a SiC ceramic powder coating according to claim 1, characterized in that: In step S3, the groove cross-section is rectangular or inverted trapezoidal, the inverted trapezoidal sidewall inclination angle is 15°–30°, and the total area of ​​the groove accounts for 25%–35% of the surface area of ​​the blank.

5. The technology for enhancing the adhesion between a carbon-carbon matrix and a SiC ceramic powder coating according to claim 1, characterized in that: In step S4, the ball mill speed is 150–200 rpm, the ball-to-material ratio is 3:1, and 1%–2% of anhydrous ethanol is added as a dispersant. The loose density of the mixed powder is ≥1.1 g / cm³. 3 .

6. The technology for enhancing the adhesion between a carbon-carbon matrix and a SiC ceramic powder coating according to claim 1, characterized in that: The heating procedure in step S5 is as follows: first, heat the temperature to 120℃ at 10℃ / min and hold for 10min, then heat it to 180℃ at 5℃ / min. After the pressure holding is completed, allow it to cool naturally to ≤60℃ before demolding.

7. The technology for enhancing the adhesion between a carbon-carbon matrix and a SiC ceramic powder coating according to claim 1, characterized in that: In step S6, the silicon material is a polycrystalline silicon block with a particle size of 1–5 mm. A 0.5 mm thick graphite paper is placed between the silicon material and the composite wafer. During the silicon infiltration process, the heating rate is 8–10 °C / min and the cooling rate is ≤5 °C / min.

8. The technology for enhancing the adhesion between a carbon-carbon matrix and a SiC ceramic powder coating according to claim 1, characterized in that: In step S7, an ultrasonic cleaning is performed between the coarse grinding and fine grinding, with a frequency of 40kHz, a power of 200W, and a time of 5min.

9. The technology for enhancing the adhesion between a carbon-carbon matrix and a SiC ceramic powder coating according to claim 1, characterized in that: The shear bond strength test in step S8 adopts the ASTM-C1292 standard, with a cross-sectional speed of 0.5 mm / min, a microscopic magnification of ≥200×, and a single-point peel area of ​​≥0.5 mm². 2 That is, it is unqualified.

10. The technology for enhancing the adhesion between a carbon-carbon matrix and a SiC ceramic powder coating according to claim 1, characterized in that: The oxygen content of the carbon / carbon composite preform, composite sheet, and final carbon-ceramic brake disc is controlled to be ≤500ppm.

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