A method for producing a high bond strength carbon ceramic brake coating disc

Abstract

The application discloses a preparation method of a carbon-toughened ceramic brake coating disc. The preparation method comprises the following steps: flattening the upper and lower surfaces of a carbon / carbon composite disc body, then performing slotting and roughening treatment, performing surface activation treatment on non-resin powder materials in a coating, and then drying the non-resin powder materials, mixing the non-resin powder materials with resin, laying one portion of coating mixture into a mold, placing the carbon / carbon composite disc body subjected to the slotting and roughening treatment into the mold, and then placing another portion of the same coating mixture on the disc body and flattening the coating mixture. Then, hot pressing, carbonization and ceramization are performed to obtain the carbon-toughened ceramic brake coating disc. The application has the advantages of simple process, easy realization of large-scale production, high bonding strength between the coating and the disc body, easy control of the thickness and flatness of the coating, and the problems of easy peeling and cracking of the coating, complex production process, low production efficiency and difficult control of the thickness of the coating can be solved.

Description

Technical Field

[0001] This invention relates to a method for preparing a high-bonding-strength carbon-ceramic brake coating disc, belonging to the field of carbon-ceramic composite material preparation technology. Background Technology

[0002] In recent years, carbon fiber reinforced carbon-based and silicon carbide ceramic matrix composites (hereinafter referred to as carbon ceramics) have been widely used in the preparation of brake discs as high-performance friction materials in the next generation of braking fields due to their excellent properties such as wear resistance, light weight and high temperature resistance.

[0003] However, existing carbon-ceramic brake discs typically employ a high-temperature melting process to infiltrate silicon into carbon / carbon composite materials (carbon fiber reinforced carbon matrix composites). Liquid silicon enters the interior of the carbon / carbon composite material through its pores, reacting with the carbon matrix to generate silicon carbide, which possesses excellent wear resistance. Considering the uneven distribution of pore size and diameter within the carbon / carbon composite material itself, the resulting silicon carbide will also exhibit uneven distribution. When applied to high-speed train braking, the immense heat generated during braking causes the brake disc temperature to rise rapidly (reaching temperatures exceeding 1000°C). While the silicon carbide-covered portions of the carbon-ceramic brake disc can withstand the high-temperature impact, the uncovered carbon fibers or carbon matrix are prone to oxidation under high-temperature conditions. This leads to oxidation and erosion pits on the carbon-ceramic brake disc, ultimately affecting the overall service life and braking performance stability of the disc.

[0004] Furthermore, considering the difficulty in processing carbon-ceramic materials, the current processing steps for carbon-ceramic brake discs generally involve first machining the carbon / carbon composite material to approximately the same dimensions as the brake disc (leaving a certain margin) before performing high-temperature melting and infiltration treatment. Then, high-temperature melting and infiltration treatment and finishing processes are performed separately. However, carbon / carbon composite materials are prone to slight dimensional deformation after high-temperature melting and infiltration treatment. This can easily lead to over-machining in certain areas during finishing, resulting in dimensions that do not meet the standard requirements of the product.

[0005] Patent CN112253660A discloses an adhesive carbon-ceramic brake disc wear-resistant coating. This coating uses an adhesive composed of low-carbon resin and alcohol to bond a wear-resistant layer (composed of silicon carbide, carbon powder, low-carbon resin, and silicon powder) to the carbon-ceramic brake disc via high-temperature curing. However, the wear-resistant coating prepared using this technology is prone to debonding from the carbon-ceramic substrate under high braking loads, especially at high speeds and high energy loads. The adhesive components, even with simple high-temperature curing, cannot ensure a tight bond between the wear-resistant coating and the carbon-ceramic substrate, resulting in a significant risk of debonding.

[0006] Patent CN113277869A describes a method involving grooved surfaces of a carbon / carbon composite disc. First, a coating slurry is applied to the grooves on the upper surface until they are filled. Then, the disc is flipped over, and the same process is repeated on the grooves on the lower surface until they are filled. This results in a carbon / carbon composite disc containing the coating slurry. The disc is then subjected to curing, carbonization, and ceramization treatments to obtain a carbon-ceramic brake coating disc. However, this method produces a coating with insufficient adhesion in harsher environments, making it prone to cracking or peeling. Furthermore, the process requires separate steps on both surfaces, resulting in a long production cycle, high energy consumption, and environmentally unfriendly solvent evaporation. Additionally, changing the coating thickness necessitates re-processing the groove depth, making the operation inconvenient. Summary of the Invention

[0007] This invention addresses the problems of existing technologies by developing a high-bonding-strength carbon-ceramic brake disc preparation technology. The carbon-ceramic brake disc prepared by this invention features a one-time coating process on both the upper and lower surfaces, no harmful solvent evaporation during the process, easily adjustable coating thickness by adding materials, high coating bonding strength, and ease of mass industrial production.

[0008] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0009] This invention discloses a method for preparing a high-bonding-strength carbon-ceramic brake disc, comprising the following steps: scraping the upper and lower surfaces of a carbon / carbon composite disc body flat, then grooving and roughening the surface; surface-activating and drying the non-resin powder material in the coating, then mixing it with resin; spreading a portion of the coating mixture evenly into a mold, placing the grooved and roughened carbon / carbon composite disc body in it, and then placing another portion of the same coating mixture on top of the disc body and spreading it evenly; then performing hot pressing, carbonization, and ceramization to obtain a carbon-ceramic brake disc.

[0010] The raw materials used in the coating, by weight percentage, include the following components:

[0011] The silicon carbide powder comprises 15-45 wt%, preferably 20-40%, and more preferably 25-35%.

[0012] The silicon powder comprises 15-35 wt%, preferably 20-40%, and more preferably 25-35%.

[0013] The fiber powder comprises 5-25 wt%, preferably 6-20%, and more preferably 10-15%.

[0014] The resin powder comprises 10-30 wt%, preferably 10-25%, and more preferably 10-20%;

[0015] Coupling agent; wherein the amount of coupling agent used is 0.1-1.5% of the total mass of (silicon carbide powder + silicon powder + fiber powder), preferably 0.3-1.2%, and more preferably 0.5-1.0%.

[0016] The surface activation treatment and drying of non-resin powder materials involves mixing silicon carbide powder, silicon powder, fiber powder, and coupling agent evenly and then drying them.

[0017] The carbon / carbon composite material disc has a density of 0.45 g / cm³. 3 ~0.55g / cm 3 Carbon fiber preforms are obtained by CVI deposition densification and / or impregnation densification.

[0018] In industrial applications, the method for preparing a high-bonding-strength carbon-ceramic brake coating disc of the present invention may include the following steps:

[0019] Step 1: Preparation of carbon / carbon composite disk

[0020] With a density of 0.45 g / cm³ 3 ~0.55g / cm 3 Carbon fiber preforms are obtained by CVI deposition densification and / or impregnation densification.

[0021] Step 2: Pretreatment of materials

[0022] The upper and lower surfaces of the carbon / carbon composite material disc are scraped flat, then grooved and roughened. The non-resin powder raw materials in the coating are surface activated and dried.

[0023] Step 3, Mixing

[0024] A surface-activated non-resin powder material is mixed with resin to obtain a coating mixture;

[0025] Step 4, hot-press coating

[0026] Add the appropriate weight of coating mixture to the mold according to the coating thickness requirements and spread it out; place the grooved carbon / carbon composite material disc into the mold; add the same weight of coating mixture as the lower layer into the mold and spread it out; close the mold and heat and pressurize according to the program. After completion, a coated carbon / carbon composite material disc is obtained.

[0027] Step 5, carbonization

[0028] Carbonize the coated carbon / carbon composite disk;

[0029] Step 6, Ceramization

[0030] The carbonized coated disc is then ceramicized to obtain a high-bonding-strength carbon-ceramic brake coated disc.

[0031] Preferably, the groove on the carbon / carbon composite material disc is U-shaped, O-shaped, or S-shaped. More preferably, it is O-shaped or U-shaped.

[0032] Preferably, the groove has a width of 0.5-3 mm and a depth of 0.2-3 mm.

[0033] When the grooves on the carbon / carbon composite material disc are O-shaped, adjacent grooves are concentric circles; and the distance between adjacent grooves is 3-18 mm, preferably 5-15 mm, and more preferably 9-15 mm. Preferably, the distance between adjacent grooves is equal.

[0034] When the groove on the carbon / carbon composite material disc is U-shaped, the maximum straight-line distance from the open end to the closed end of the U-shape is 25-65mm, the width of the open end is 10-35mm, and the spacing between adjacent U-shaped grooves on the circular surface concentric with the disc surface is 3-20mm.

[0035] When the groove on the carbon / carbon composite material disc is U-shaped, and there are at least two rings formed by multiple U-shaped grooves, the distance between the two closest U-shaped grooves on two adjacent rings is 5-15mm.

[0036] When multiple U-shaped grooves form a ring, the open end of one U-shaped groove faces the outer edge of the carbon / carbon composite disk; then the closed end of the adjacent U-shaped groove faces the outer edge of the carbon / carbon composite disk. This alternating arrangement forms a ring.

[0037] Preferably, the grooving cutter rotates at a speed of ≤10000 r / min to produce carbon fiber fluff on the surface of the groove; the preferred rotation speed is 1000-5000 r / min.

[0038] Preferably, the fiber powder is one or more of carbon fiber, silicon carbide fiber, feldspar fiber, etc.

[0039] The resin powder is one or more of high-adhesion resins such as epoxy resin, phenolic resin, and polysiloxane resin;

[0040] The silicon carbide micro powder has a particle size ≤45µm, preferably 10-25µm; the silicon micro powder has a particle size ≤45µm, preferably 10-25µm; and the fiber powder has a length ≤2mm, preferably 0.1-0.5mm.

[0041] Preferably, the coupling agent is a silane coupling agent.

[0042] As a further preferred embodiment, the coupling agent is selected from at least one of KH550, KH560, and KH570. Its preferred dosage is 0.3-1.2%, more preferably 0.5-1.0%.

[0043] This invention discloses a method for preparing a high-bonding-strength carbon-ceramic brake disc. Different shaped grooves on the carbon / carbon composite disc body help increase the physical bonding strength between the coating and the disc body. Simultaneously, the carbon fiber fuzz formed by the breakage of some fibers during the groove processing has high strength, further enhancing the bonding strength between the coating and the carbon / carbon matrix. A special non-resin powder with a coupling agent is used to increase the bonding force between the powder and the resin, as well as with the carbon fibers. During heating and pressurization, the resin fully bonds with the powder in the coating and simultaneously penetrates into the carbon / carbon composite disc body. The curing process forms a three-dimensional network structure, allowing the coating to be better bonded to the substrate disc. Silicon reacts with the coating during the melting and infiltration process.

[0044] In a preferred embodiment, in addition to the resin powder, the other raw material powders mentioned above are first mixed in proportion, and then the hydrolyzed coupling agent alcohol solution is added in proportion. After mixing evenly again, the mixture is left to stand open until the alcohol has completely evaporated, and then the resin powder is added in proportion.

[0045] In a preferred embodiment, the carbon / carbon composite material disc has a density of 1.35-1.5 g / cm3, and the disc is a long fiber disc or a short fiber disc;

[0046] In the preferred embodiment, the pressure during hot pressing is 0.5-25 MPa, the curing temperature is 150-210℃, and the curing time is 30-60 min.

[0047] In a preferred embodiment, the carbonization treatment temperature is 800℃~1000℃, the holding time is 2~4h; the heating rate is ≤30℃ / h, preferably 10℃ / h~20℃ / h; and the cooling rate is ≤60℃ / h, preferably 20℃~40℃ / h.

[0048] In a preferred embodiment, a silicon vapor deposition process is used to ceramicize the carbon / carbon composite material disk containing the coating slurry after carbonization treatment; the silicon vapor deposition temperature is 1500℃~1700℃, the silicon vapor deposition time is 1~3h, and after the silicon vapor deposition is completed, the cooling rate is controlled to be ≤80℃ / h, preferably 40℃ / h~70℃ / h.

[0049] In actual operation, silicon powder is laid in a graphite crucible, and then the carbonized coating is placed in the graphite crucible. The interface between the crucible and the silicon powder is separated by a graphite pad of a certain height to ensure that the height of the interface between the crucible and the silicon powder is ≥100mm, preferably 100mm to 300mm.

[0050] In actual operation, carbon ceramic brake discs are obtained by ceramicizing and then fine machining.

[0051] The present invention also provides a carbon ceramic brake coating disc with high bonding strength prepared by the above preparation method.

[0052] The present invention adopts the above technical solution and has the following beneficial effects:

[0053] 1. The present invention provides a method for preparing a high-bonding-strength carbon-ceramic brake disc. This method involves grooving and roughening the carbon / carbon composite disc body, surface activation of non-resin powder, and molding under pressure. This results in a bonding strength between the coating and the disc body exceeding 33 MPa, meeting the more stringent braking requirements of existing high-speed trains under high-speed operating conditions. Simultaneously, the coating is less prone to cracking and peeling.

[0054] 2. The present invention also employs a method of first modifying silicon carbide powder, silicon powder, and fiber powder with a silane coupling agent, and then mixing them with resin. Combined with the grooving method, grooving depth, spacing, and subsequent hot pressing, this not only improves the powder's resistance to cracking and peeling during curing and carbonization, but also increases the product's shear strength and reduces the product's wear rate.

[0055] 3. This invention proposes to prepare the coating by hot pressing, which can solve the problem of uneven coating thickness caused by overflow after slurry application, and can also achieve flexible control of coating thickness by adding the weight of the coating mixture.

[0056] In addition, the coating proposed in this invention has no harmful or easily volatile components during its preparation process; it requires less processing and saves materials; the process is simple and easy to achieve large-scale industrial mass production. At the same time, the coating has a bright and smooth appearance and its dimensional accuracy is easy to control precisely, which can effectively solve the problem of inaccurate dimensional control when the ceramic brake disc is machined. Attached Figure Description

[0057] Figure 1 A schematic diagram of an O-groove in a carbon / carbon composite material disc;

[0058] Figure 2 A schematic diagram of a U-shaped groove in a carbon / carbon composite disk. Detailed Implementation

[0059] The present invention will be further described in detail below with reference to the accompanying drawings.

[0060] Example 1

[0061] Step 1: Preparation of carbon / carbon composite disk

[0062] T700 carbon fiber was used to make non-woven fabric and a mesh layer. These layers were stacked in a manner of mesh layer / 0° non-woven fabric / mesh layer / 90° non-woven fabric. Then, needle punching was performed in a direction perpendicular to the stacked layers to obtain a carbon fiber preform plate with a density of 0.45 g / cm³. Then, according to the required size profile of the carbon ceramic disc, a carbon fiber preform disc with the same inner and outer diameters as the carbon ceramic disc was extracted from the carbon fiber preform plate. Then, CVI deposition was used to densify the carbon fiber preform disc, with propylene as the gas source, to finally obtain a carbon / carbon composite disc with a density of 1.35 g / cm³.

[0063] Step 2: Material Pretreatment. Scrape the upper and lower surfaces of the carbon / carbon composite disc flat, then groove and roughen it at 1000 r / min. The groove shape is O-shaped, 1 mm wide, 1 mm deep, and the groove spacing is 10 mm (the friction surface is annular; the difference between the inner and outer diameters of the annulus is 4.8 cm). Set aside for later use. Mix 35 wt% silicon carbide powder (20 μm particle size), 35 wt% silicon powder (20 μm particle size), 15 wt% carbon fiber powder (0.3 mm length), and coupling agent KH560 from the coating; the amount of coupling agent KH560 is 0.5% of the total mass of (silicon carbide powder + silicon powder + fiber powder). Mix the prepared silicon carbide powder, silicon powder, fiber powder, and coupling agent KH560 evenly with an alcohol solution, spread out and allow the alcohol to dry, obtaining a non-resin powder mixture.

[0064] Step 3, Mixing. The surface-activated non-resin powder mixture is mixed thoroughly with 15 wt% phenolic resin powder (no solvent should be added) to obtain the coating mixture;

[0065] Step 4, Hot Press Coating. Add the appropriate weight of coating mixture to the mold according to the required coating thickness and spread it evenly; place the grooved carbon / carbon composite disc into the mold; add the same weight of coating mixture as the lower layer into the mold and spread it evenly; close the mold and heat according to the program: temperature 150-200℃, pressure 1-15MPa, curing time 45min. After completion, demold to obtain the coated carbon / carbon composite disc;

[0066] Step 5, carbonization. The coated carbon / carbon composite disc is carbonized at a temperature of 900℃ for 3 hours, with a heating rate of 15℃ / h and a cooling rate of 30℃ / h.

[0067] Step 6, Ceramization. The carbonized coated disk is placed in a high-temperature vacuum furnace for high-temperature ceramization treatment using a high-temperature vapor deposition silicon diffusion method. The specific process is as follows: First, sufficient silicon powder is laid in a graphite crucible. Then, the carbon / carbon composite disk with the carbonized coating is placed in the graphite crucible, and the interface between the disk and the silicon powder is separated by a graphite pad of a certain height, ensuring that the height of the interface between the disk and the silicon powder is 100mm. The vapor deposition silicon diffusion temperature is 1600℃ for 2 hours. After the vapor deposition silicon diffusion is completed, the cooling rate is controlled at 50℃ / h to obtain a high-bonding-strength carbon-ceramic brake coating disk.

[0068] Comparative Example 1

[0069] A high-bonding-strength carbon-ceramic brake coating disc is prepared as described in Example 1, except that step 2 of Example 1, involving grooving and roughening of the carbon / carbon preform disc and surface activation treatment of the non-resin powder material, is omitted. The other preparation steps and conditions are the same as in Example 1. After hot pressing, the coating peels off directly.

[0070] Comparative Example 2

[0071] Other conditions are the same as in Example 1; the difference is that no silane coupling agent is added; the resulting product exhibits the following properties: coating cracking and peeling during carbonization.

[0072] Comparative Example 3

[0073] Other conditions are the same as in Example 1; the difference is that silicon carbide powder, silicon powder, carbon fiber powder, coupling agent KH560, and phenolic resin are added together, stirred evenly, and then dried; the properties of the resulting product are: the powder clumps severely and adheres to the inner wall of the mixing equipment, making it difficult to separate.

[0074] Comparative Example 4

[0075] Other conditions were the same as in Example 1; the difference was that the tool rotation speed was 11000 r / min during grooving, and there were virtually no fiber lint in the groove. The coating was good after carbonization, but some of the coating peeled off and cracked after melting and infiltration.

[0076] Example 2

[0077] Step 1: Preparation of carbon / carbon composite disk

[0078] T700 carbon fiber was used to make non-woven fabric and a mesh layer. These layers were stacked in a manner of mesh layer / 0° non-woven fabric / mesh layer / 90° non-woven fabric. Then, needle punching was performed in a direction perpendicular to the stacked layers to obtain a carbon fiber preform plate with a density of 0.45 g / cm³. Then, according to the required size profile of the carbon ceramic disc, a carbon fiber preform disc with the same inner and outer diameters as the carbon ceramic disc was extracted from the carbon fiber preform plate. Then, CVI deposition was used to densify the carbon fiber preform disc, with propylene as the gas source, to finally obtain a carbon / carbon composite disc with a density of 1.35 g / cm³.

[0079] Step 2: Material Pretreatment. Scrape the upper and lower surfaces of the carbon / carbon composite disc flat, then groove and roughen it at 5000 r / min. The groove shape is O-shaped, with a groove width of 1.5 mm, a groove depth of 1.5 mm, and a groove spacing of 15 mm (the friction surface is annular; the difference between the inner and outer diameters of the annulus is 4.8 cm). Set aside for later use. Mix 35 wt% silicon carbide powder with a particle size of 25 μm, 30 wt% silicon powder with a particle size of 25 μm, 15 wt% carbon fiber powder with a length of 0.5 mm, and coupling agent KH550 from the coating; the amount of coupling agent KH550 is 0.8% of the total mass of (silicon carbide powder + silicon powder + fiber powder). Mix the prepared silicon carbide powder, silicon powder, fiber powder, and coupling agent KH550 evenly with an alcohol solution, spread out and let the alcohol dry to obtain a non-resin powder mixture.

[0080] Step 3, Mixing. The surface-activated non-resin powder mixture is mixed thoroughly with 25 wt% phenolic resin powder (no solvent added) to obtain the coating mixture;

[0081] Step 4, Hot-press Coating. Add the appropriate weight of coating mixture to the mold according to the required coating thickness and spread it evenly; place the grooved carbon / carbon composite disc into the mold; add the same weight of coating mixture as the lower layer into the mold and spread it evenly; close the mold and heat according to the program: temperature 150-190℃, pressure 1-15MPa, curing time 60min. After completion, demold to obtain the coated carbon / carbon composite disc;

[0082] Step 5, carbonization. The coated carbon / carbon composite disc is carbonized at a temperature of 1000℃ for 2 hours, with a heating rate of 20℃ / h and a cooling rate of 40℃ / h.

[0083] Step 6, Ceramization. The carbonized coated disk is placed in a high-temperature vacuum furnace for high-temperature ceramization treatment using a high-temperature vapor deposition silicon diffusion method. The specific process is as follows: First, sufficient silicon powder is laid in a graphite crucible. Then, the carbon / carbon composite disk with the carbonized coating is placed in the graphite crucible, and the interface between the disk and the silicon powder is separated by a graphite pad of a certain height, ensuring that the height of the interface between the disk and the silicon powder is 200mm. The vapor deposition silicon diffusion temperature is 1700℃ for 1 hour. After the vapor deposition silicon diffusion is completed, the cooling rate is controlled at 70℃ / h to obtain a high-bonding-strength carbon-ceramic brake coating disk.

[0084] Example 3

[0085] Step 1: Preparation of carbon / carbon composite disk

[0086] T700 carbon fiber was used to make non-woven fabric and a mesh layer. These layers were stacked in a manner of mesh layer / 0° non-woven fabric / mesh layer / 90° non-woven fabric. Then, needle punching was performed in a direction perpendicular to the stacked layers to obtain a carbon fiber preform plate with a density of 0.45 g / cm³. Then, according to the required size profile of the carbon ceramic disc, a carbon fiber preform disc with the same inner and outer diameters as the carbon ceramic disc was extracted from the carbon fiber preform plate. Then, CVI deposition was used to densify the carbon fiber preform disc, with propylene as the gas source, to finally obtain a carbon / carbon composite disc with a density of 1.35 g / cm³.

[0087] Step 2: Material Pretreatment. Scrape the upper and lower surfaces of the carbon / carbon composite disc flat, then groove and roughen it at 2500 r / min. The groove shape is U-shaped, with a width of 1.5 mm, a depth of 1.5 mm, a maximum straight-line distance of 40 mm from the open end to the closed end of the U-shape, and a width of 20 mm at the open end. When one of the U-shaped open ends faces the outer edge of the carbon / carbon composite disc, the closed end of the adjacent U-shaped groove faces the outer edge of the carbon / carbon composite disc. (The friction surface is annular; the difference between the inner and outer diameters of the annulus is 4.8 cm.) Set aside for later use; add 25wt% silicon carbide powder with a particle size of 10µm, 35wt% silicon powder with a particle size of 10µm, 20wt% carbon fiber powder with a length of 0.2mm, and coupling agent KH570 to the coating; wherein the amount of coupling agent KH570 is 1.0% of the total mass of (silicon carbide powder + silicon powder + fiber powder). Mix the prepared silicon carbide powder, silicon powder, fiber powder, and coupling agent KH570 evenly with an alcohol solution, spread them out and let the alcohol dry to obtain a non-resin powder mixture.

[0088] Step 3, Mixing. The surface-activated non-resin powder mixture is mixed thoroughly with 20 wt% phenolic resin powder (no solvent should be added) to obtain the coating mixture;

[0089] Step 4, Hot-press Coating. Add the appropriate weight of coating mixture to the mold according to the required coating thickness and spread it evenly; place the grooved carbon / carbon composite disc into the mold; add the same weight of coating mixture as the lower layer into the mold and spread it evenly; close the mold and heat according to the program: temperature 160-210℃, pressure 1-15MPa, curing time 60min. After completion, demold to obtain the coated carbon / carbon composite disc;

[0090] Step 5, carbonization. The coated carbon / carbon composite disc is carbonized at a temperature of 800℃ for 4 hours, with a heating rate of 15℃ / h and a cooling rate of 20℃ / h.

[0091] Step 6, Ceramization. The carbonized coated disk is placed in a high-temperature vacuum furnace for high-temperature ceramization treatment using a high-temperature vapor deposition silicon diffusion method. The specific process is as follows: First, sufficient silicon powder is laid in a graphite crucible. Then, the carbon / carbon composite disk with the carbonized coating is placed in the graphite crucible, and the interface between the disk and the silicon powder is separated by a graphite pad of a certain height, ensuring that the height of the interface between the disk and the silicon powder is 100mm. The vapor deposition silicon diffusion temperature is 1500℃ for 3 hours. After the vapor deposition silicon diffusion is completed, the cooling rate is controlled at 40℃ / h to obtain a high-bonding-strength carbon-ceramic brake coating disk.

[0092] Example 4

[0093] Step 1: Preparation of carbon / carbon composite disk

[0094] T700 carbon fiber was used to make non-woven fabric and a mesh layer. These layers were stacked in a manner of mesh layer / 0° non-woven fabric / mesh layer / 90° non-woven fabric. Then, needle punching was performed in a direction perpendicular to the stacked layers to obtain a carbon fiber preform plate with a density of 0.45 g / cm³. Then, according to the required size profile of the carbon ceramic disc, a carbon fiber preform disc with the same inner and outer diameters as the carbon ceramic disc was extracted from the carbon fiber preform plate. Then, CVI deposition was used to densify the carbon fiber preform disc, with propylene as the gas source, to obtain a carbon / carbon composite disc with a density of 1.4 g / cm³.

[0095] Step 2: Material Pretreatment. Scrape the upper and lower surfaces of the carbon / carbon composite disc flat, then groove and roughen it at 5000 r / min. The groove shape is O-shaped, with a groove width of 1.5 mm, a groove depth of 1.5 mm, and a groove spacing of 15 mm. Set aside for later use. Mix 40 wt% silicon carbide powder with a particle size of 25 μm, 30 wt% silicon powder with a particle size of 25 μm, 20 wt% carbon fiber powder with a length of 0.4 mm, and coupling agent KH550 from the coating. The amount of coupling agent KH550 is 0.8% of the total mass of (silicon carbide powder + silicon powder + fiber powder). Mix the prepared silicon carbide powder, silicon powder, fiber powder, and coupling agent KH550 evenly with an alcohol solution, spread out and let the alcohol dry to obtain a non-resin powder mixture.

[0096] Step 3, Mixing. The surface-activated non-resin powder mixture is mixed thoroughly with 10 wt% phenolic resin powder to obtain the coating mixture;

[0097] Step 4, Hot Press Coating. Add the appropriate weight of coating mixture to the mold according to the required coating thickness and spread it evenly; place the grooved carbon / carbon composite material disc into the mold; add the same weight of coating mixture as the lower layer to the mold and spread it evenly; close the mold and heat according to the program: temperature 160-210℃, pressure 4-17MPa, curing time 35min. After completion, demold to obtain the coated carbon / carbon composite material disc;

[0098] Step 5, carbonization. The coated carbon / carbon composite disc is carbonized at a temperature of 850℃ for 2 hours, with a heating rate of 20℃ / h and a cooling rate of 40℃ / h.

[0099] Step 6, Ceramization. The carbonized coated disk is placed in a high-temperature vacuum furnace for high-temperature ceramization treatment using a high-temperature vapor deposition silicon diffusion method. The specific process is as follows: First, sufficient silicon powder is laid in a graphite crucible. Then, the carbon / carbon composite disk with the carbonized coating is placed in the graphite crucible, and the interface between the disk and the silicon powder is separated by a graphite pad of a certain height, ensuring that the height of the interface between the disk and the silicon powder is 100mm. The vapor deposition silicon diffusion temperature is 1700℃, and the time is 1.5h. After the vapor deposition silicon diffusion is completed, the cooling rate is controlled at 60℃ / h to obtain a high-bonding-strength carbon-ceramic brake coating disk.

[0100] Comparative Example 5 is a high-bonding-strength carbon-ceramic brake coating disc. The specific preparation steps are the same as in Example 4. The difference is that step 2 of Example 4, which involves grooving and roughening the carbon / carbon preform disc, is omitted in Comparative Example 5. The other preparation steps and conditions are the same as in Example 4.

[0101] The carbon-ceramic brake disc obtained above was subjected to shear strength tests between the coating and the ceramic substrate, as well as AK-master wear performance tests (performance evaluation of dynamic friction coefficient and wear rate). The obtained test data are shown in Table 1.

[0102] Table 1:

[0103]

[0104] The data obtained from Table 1 show that: First, the shear strength between the coating and the carbon-ceramic substrate prepared by this invention reaches over 33 MPa, and there is no detachment during friction testing, resulting in low wear rate and high dynamic friction coefficient. In Comparative Example 1, the disc without grooving or roughening and without coupling agent detached after molding. In Comparative Example 2, grooving without coupling agent resulted in detachment and cracking during carbonization. In Comparative Example 3, the resin was added along with other powders and a coupling agent. Due to the compatibility of the resin and alcohol in the coupling agent, the resin adhered to the inner wall of the mixing equipment, and the powder agglomerated severely. In Comparative Example 4, high-speed grooving was used during grooving, resulting in a smooth groove with virtually no short fibers. However, the coating cracked and detached during melting and infiltration. In Comparative Example 5, the coating remained intact throughout the entire preparation and testing process, but the shear strength was low. Therefore, the carbon-ceramic brake disc prepared by this invention has high bonding strength between the coating and the carbon-ceramic substrate, which can better meet the requirements of extreme braking during braking. Furthermore, no harmful gases are generated during the preparation process, and the preparation process is simple and easy to standardize for mass production.

[0105] The above content provides a detailed description of a high-bonding-strength carbon-ceramic brake disc according to the present invention, which can be applied to fields such as automotive or rail transit braking. However, the present invention is not limited to the specific embodiments described above. Therefore, any improvements, equivalent modifications, or substitutions made based on the technical points of the present invention are within the scope of protection of the present invention.

Claims

1. A method of making a high bond strength carbon ceramic brake coating disc, characterized by: The method comprises the following steps: flattening the upper and lower surfaces of a carbon / carbon composite disc, then performing slotting and roughening treatment, performing surface activation treatment and air-drying on non-resin powder materials in a coating, mixing the coating with resin, laying one portion of the coating mixture into a mold, placing the carbon / carbon composite disc subjected to slotting and roughening treatment into the mold, and then placing another portion of the same coating mixture on the disc and flattening the coating mixture. Then, hot pressing, carbonization and ceramization are performed to obtain a carbon ceramic braking coating disc. The raw materials for the coating comprise the following components in percentage by mass: 15-45wt% silicon carbide powder, 15-35wt% silicon powder, 5-25wt% fiber powder, 10-30wt% resin powder and coupling agent for treating the powder; the amount of the coupling agent is 0.1-1.5% of the total mass of the silicon carbide powder, the silicon powder and the fiber powder; The width of the slot is 0.5-3mm, and the depth of the slot is 0.2-3mm. The rotating speed of the slotting tool is 1000-5000r / min, so that carbon fiber fluff is generated on the surface of the slot. The surface activation treatment and air-drying of the non-resin powder materials are performed by uniformly mixing the prepared silicon carbide powder, silicon powder, fiber powder and coupling agent and then air-drying the mixture. The pressure during the hot pressing process is 0.5-25MPa, the curing temperature is 150-210℃, and the curing time is 30-60min. The carbonization temperature is 800-1000℃, the holding time is 2-4h, the temperature rising rate is ≤30℃ / h, and the temperature falling rate is ≤60℃ / h. The carbon / carbon composite disc with the coating slurry after the carbonization treatment is subjected to ceramization treatment by using a silicon vapor deposition process; the temperature for the silicon vapor deposition is 1500-1700℃, the time for the silicon vapor deposition is 1-3h, and after the completion of the silicon vapor deposition, the temperature falling rate is controlled to be ≤80℃ / h.

2. The method for preparing a high-bonding-strength carbon ceramic brake coating disc according to claim 1, characterized in that: The shape of the slot on the carbon / carbon composite disc is at least one of U-shaped, O-shaped or S-shaped.

3. The method for preparing a high-bonding-strength carbon ceramic brake coating disc according to claim 2, characterized in that: The shape of the slot on the carbon / carbon composite disc is U-shaped and / or O-shaped.

4. The method for preparing a high-bonding-strength carbon ceramic brake coating disc according to claim 1, characterized in that: The fiber powder is one or more of carbon fiber, silicon carbide fiber and feldspar fiber. The resin powder is one or more of epoxy resin, phenolic resin and polysiloxane resin. The particle size of the silicon carbide powder is 10-25μm, the particle size of the silicon powder is 10-25μm, and the length of the fiber powder is 0.1-0.5mm.

5. The method for preparing a high-bonding-strength carbon ceramic brake coating disc according to claim 1, characterized in that: The coupling agent is a silane coupling agent.

6. The method for preparing a high-bonding-strength carbon ceramic brake coating disc according to claim 5, characterized in that: The coupling agent is at least one of KH550, KH560 and KH570.

7. The method for preparing a high-bonding-strength carbon ceramic brake coating disc according to claim 1, characterized in that: The density of the carbon / carbon composite disc is 1.35-1.5g / cm3, and the disc is a long fiber disc or a short fiber disc.

8. The method for preparing a high-bonding-strength carbon ceramic brake coating disc according to claim 1, characterized in that: The temperature rising rate of the carbonization process is 10-20℃ / h, and the temperature falling rate is 20-40℃ / h. After the completion of the silicon vapor deposition, the temperature falling rate is controlled to be 40-70℃ / h.

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