Carbon ceramic disc brake pad and preparation method thereof

Abstract

This invention provides a carbon ceramic disc brake pad and its preparation method, comprising an inner layer and an outer layer. The inner layer contains the following raw materials in parts by weight: 30 parts reinforcing fiber and 20-24 parts binder. The outer layer contains the following raw materials in parts by weight: 30 parts reinforcing fiber, 16-20 parts binder, 8-12 parts modified disulfide, and 2-4 parts methyltrimethoxysilane. The modified disulfide includes at least one of graphene-modified molybdenum disulfide and carbon nanotube-modified tungsten disulfide. Water-guiding microgrooves are provided on the friction surface of the outer layer. The carbon ceramic disc brake pad provided by this invention maintains a friction coefficient stable above 0.40 in the low-temperature range of -20℃ to 50℃ and under humid conditions, with friction coefficient fluctuation controlled below 0.06, and a wet friction coefficient attenuation rate ≤10%.

Description

Technical Field

[0001] This application relates to the field of automotive braking materials technology, and in particular to a carbon ceramic disc brake pad and its preparation method. Background Technology

[0002] Carbon ceramic brake discs are widely used in braking systems of high-end automobiles, racing cars, and special vehicles due to their excellent properties such as light weight, high temperature resistance, and long wear life. However, carbon ceramic discs have high surface hardness and low surface energy, resulting in poor interfacial compatibility with traditional brake pad friction materials. This leads to a common problem of severe degradation of the friction coefficient in brake pads under low temperature (-20℃~50℃) and wet conditions.

[0003] CN116622186A discloses "an organic ceramic brake pad for carbon-ceramic brake discs of road vehicles and its preparation method." This ceramic brake pad is prepared using a mixture of 1%–4% phenolic resin, 1%–5% boron-modified phenolic resin, 1%–6% carbon fiber, 8%–15% steel fiber, 15%–20% reduced iron powder, 6%–12% copper powder, and 4%–6% molybdenum disulfide, employing a mixing, hot pressing, and curing process to produce a homogeneous organic ceramic brake pad. The brake pad formulation contains a large amount of steel fiber, reduced iron powder, and copper powder, resulting in a high metal content. At low temperatures, the rapid thermal conductivity of the metal makes it difficult to maintain the interface temperature. The insufficient low-temperature activity of molybdenum disulfide leads to a significant decrease in the friction coefficient under low-temperature conditions. Furthermore, the friction material layer has a homogeneous structure without functional layering, making it impossible to simultaneously meet the multiple requirements of inner layer adhesion and thermal conductivity, as well as outer layer low-temperature lubrication and wet hydrophobicity.

[0004] CN112483563A discloses "a copper-free resin-based friction material for matching carbon-ceramic brake discs and its preparation method." This material mainly consists of four parts: binder, reinforcing fibers, friction modifier, and other fillers and additives, and is prepared through mixing, molding, and heat treatment. This material adopts a homogeneous friction layer structure with no gradient functional layering design, making it impossible to achieve multiple performance divisions; it uses conventional lubrication systems such as graphite and molybdenum disulfide, making it difficult to fully utilize lubrication activity at low temperatures.

[0005] CN116255411A discloses "a carbon-ceramic brake pad for use with a carbon-ceramic brake disc and its preparation method," which consists of a carbon-ceramic liner and a carbon-ceramic friction surface connected by a tenon and mortise structure. The friction surface has grooves for heat dissipation and chip removal. This carbon-ceramic brake pad uses an integrated molding process for carbon-ceramic composite materials. The width and depth of the grooves are both 1mm to 5mm. Its main function is chip removal and heat dissipation, rather than a hydrophobic and water-guiding design for wet water films. During braking in rainy weather or on flooded roads, a water film easily forms at the friction interface, disrupting the contact and reducing braking safety.

[0006] CN120774659A discloses "a brake pad adapted to carbon ceramic brake discs and its preparation process," employing a formulation system of 25%–57% reinforcing fiber, 22%–49% lubricant, 7%–17% binder, 7.2%–28.1% friction modifier, and 3%–23% filler. The lubricant composition is as follows: 8%–18% graphene composite lubricating particles, 13%–23% composite graphite, and 1%–8% antimony sulfide. This material formulation has a high lubricant content, lacks functional layering and hydrophobic / water-conducting structures, and does not design a low-temperature activated lubrication system for low-temperature operating conditions.

[0007] In summary, existing carbon ceramic disc brake pads mainly have the following defects: In existing technologies, the friction material layers are all homogeneous structures without gradient functional layering, which cannot simultaneously achieve low-temperature lubrication and wet hydrophobicity; the friction material surface lacks a dedicated hydrophobic design, which easily forms a water film in wet conditions, damaging the interface, resulting in a large wet friction coefficient attenuation rate and low braking safety. Summary of the Invention

[0008] The present invention is made in view of the above-mentioned problems, and its purpose is to provide a carbon ceramic disc brake pad and its preparation method, so as to solve the technical problem that the friction coefficient of existing brake pads matched with carbon ceramic discs generally declines under low temperature and wet conditions.

[0009] Specifically, the first aspect of the present invention provides a carbon ceramic disc brake pad, comprising an inner layer and an outer layer; the inner layer comprises the following raw materials in parts by weight: 30 parts of reinforcing fiber and 20 to 24 parts of binder; the outer layer comprises the following raw materials in parts by weight: 30 parts of reinforcing fiber, 16 to 20 parts of binder, 8 to 12 parts of modified disulfide, and 2 to 4 parts of methyltrimethoxysilane; the modified disulfide includes at least one of graphene-modified molybdenum disulfide and carbon nanotube-modified tungsten disulfide, and the friction surface of the outer layer is provided with water-guiding microgrooves.

[0010] Optionally, the thickness of the inner layer is 2.5 mm to 3.5 mm.

[0011] Optionally, the thickness of the outer layer is 1.5 mm to 2.5 mm.

[0012] Optionally, the reinforcing fibers in the inner layer and the reinforcing fibers in the outer layer each independently include at least one of carbon fiber, basalt fiber, chopped glass fiber, and chopped aramid fiber.

[0013] Optionally, the adhesive in the inner layer and the adhesive in the outer layer are both independently selected from a blend of cashew nut shell oil-modified phenolic resin and polyimide resin.

[0014] Optionally, the graphene-modified molybdenum disulfide is prepared by ball milling graphene and molybdenum disulfide powder, dispersing them in ethanol, adding a silane coupling agent, and heating.

[0015] Optionally, the carbon nanotube-modified tungsten disulfide is prepared by ball milling and mixing carbon nanotubes and tungsten disulfide powder, dispersing them in ethanol, adding a silane coupling agent, and heating.

[0016] Optionally, the raw materials for preparing the inner layer may also include thermally conductive fillers.

[0017] Optionally, the raw materials for preparing the outer layer also include a synergistic lubricant.

[0018] Optionally, the raw materials for preparing the outer layer may also include lubricating microcapsules.

[0019] Optionally, the blend of cashew nut shell oil-modified phenolic resin and polyimide resin is prepared by mixing and dissolving cashew nut shell oil-modified phenolic resin, polyimide resin and N,N-dimethylformamide.

[0020] Optionally, the mass ratio of the cashew nut shell oil-modified phenolic resin to the polyimide resin is 1 to 5:1.

[0021] Optionally, the mass ratio of graphene to molybdenum disulfide powder in the graphene-modified molybdenum disulfide is 1:1 to 5.

[0022] Optionally, the silane coupling agent in the graphene-modified molybdenum disulfide accounts for 1% to 3% of the total mass of the graphene and molybdenum disulfide powder.

[0023] Optionally, the mass ratio of carbon nanotubes to tungsten disulfide powder in the carbon nanotube-modified tungsten disulfide is 1:1 to 5.

[0024] Optionally, the silane coupling agent in the carbon nanotube-modified tungsten disulfide accounts for 1% to 3% of the total mass of the carbon nanotubes and tungsten disulfide powder.

[0025] Optionally, the heating temperature in the graphene-modified molybdenum disulfide and the carbon nanotube-modified tungsten disulfide are both independently set to 60°C to 80°C.

[0026] Optionally, the thermally conductive filler in the inner layer includes at least one of flake graphite and aluminum nitride.

[0027] Optionally, the synergistic lubricant in the outer layer is hexagonal boron nitride.

[0028] Optionally, the lubricating microcapsules include at least one of urea-formaldehyde resin-coated lubricating oil microcapsules and urea-formaldehyde resin-coated liquid paraffin microcapsules.

[0029] Optionally, the thermally conductive filler in the inner layer is 14 to 18 parts.

[0030] Optionally, the synergistic lubricant in the outer layer is 4 to 8 parts.

[0031] Optionally, the lubricating microcapsules in the outer layer are 2 to 6 parts.

[0032] Optionally, the preparation method of the lubricating microcapsule includes: mixing urea and formaldehyde, adjusting the pH to alkaline, and heating to react to obtain a urea-formaldehyde prepolymer; mixing and emulsifying the lubricating core material, emulsifier, and water to obtain a core material emulsion; and mixing the urea-formaldehyde prepolymer and the core material emulsion, adjusting the pH to acidic, and heating to react to obtain the final product.

[0033] Optionally, the molar ratio of urea to formaldehyde is 1:1.8 to 2.

[0034] Optionally, the alkaline pH value is 8 to 9.

[0035] Optionally, the heating temperature of the urea and formaldehyde is 60℃~80℃.

[0036] Optionally, the acidic pH value is 4 to 5.

[0037] Optionally, the heating temperature of the urea-formaldehyde prepolymer and the core material emulsion is 70°C to 80°C.

[0038] Optionally, the lubricating core material is lubricating oil or liquid paraffin.

[0039] Optionally, the emulsifier is sodium dodecylbenzenesulfonate.

[0040] Optionally, the mass ratio of the lubricating core material, emulsifier and water is 1:0.01 to 0.03:3 to 5.

[0041] Optionally, the mass ratio of the urea-formaldehyde prepolymer to the lubricating core material is 0.5 to 0.8:1.

[0042] The first aspect of the present invention provides a method for preparing carbon ceramic disc brake pads, comprising the following steps: mixing the raw materials for preparing the inner layer into a slurry, coating it onto the surface of a steel backing and drying it to obtain the inner layer; mixing the raw materials for preparing the outer layer and laying them on the inner layer to form the outer layer, hot pressing it into shape, and pressing water-guiding microgrooves on the friction surface of the outer layer during the hot pressing process, and then performing post-curing treatment and vacuum impregnation treatment in sequence.

[0043] Optionally, the steel backing is TC4 titanium alloy.

[0044] Optionally, the hot pressing temperature is 180℃~220℃.

[0045] Optionally, the pressure of the hot pressing is 30MPa to 40MPa.

[0046] Optionally, the hot pressing time is 20 min to 25 min.

[0047] Optionally, the width of the water-guiding microchannels is 0.2mm to 0.4mm, the depth is 0.4mm to 0.6mm, and the spacing is 3mm to 5mm.

[0048] Optionally, the post-curing treatment is a stepped temperature curing treatment.

[0049] Optionally, the vacuum impregnation process includes sequentially injecting impregnation slurry and pressurized permeation.

[0050] Optionally, the heating rate of the step-heat curing treatment is 1℃ / min to 3℃ / min.

[0051] Optionally, the step heating and curing process is divided into three insulation stages, including a first insulation stage, a second insulation stage, and a third insulation stage.

[0052] Optionally, the vacuum degree during the injection of the impregnation slurry is 5 kPa to 6 kPa.

[0053] Optionally, the pressure of the pressurized permeation is 0.1 MPa to 0.2 MPa.

[0054] Optionally, the pressure holding time for the pressurized permeation is 5 min to 15 min.

[0055] Optionally, the temperature of the first insulation section is 140℃~160℃.

[0056] Optionally, the temperature of the second insulation section is 180℃~220℃.

[0057] Optionally, the temperature of the third insulation section is 240℃~260℃.

[0058] Optionally, the insulation time of the first insulation section, the second insulation section and the third insulation section are all independently 1.5h to 2.5h.

[0059] Optionally, the impregnation slurry for vacuum impregnation treatment is a mixture of lubricating microcapsules, epoxy resin, and ethanol.

[0060] Optionally, the vacuum impregnation process may further include centrifugation and curing.

[0061] Optionally, the mass ratio of the lubricating microcapsule to the epoxy resin is 2 to 4:1.

[0062] Optionally, the curing temperature is 70℃~90℃.

[0063] Compared with the prior art, the present invention has the following beneficial effects: This invention improves the compatibility between brake pads and carbon ceramic discs by optimizing the raw materials and their proportions and functional stratification in brake pad preparation. In the low temperature range of -20℃ to 50℃ and under wet conditions, the average friction coefficient is stable above 0.40, the friction coefficient fluctuation value is controlled below 0.06, and the wet friction coefficient attenuation rate is ≤10%. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of this application clearer, the following description and illustration are provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0065] Obviously, the following description is merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0066] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0067] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0068] In the embodiments and comparative examples of the present invention, the length of the carbon fiber used is 1 mm to 3 mm; The length of the basalt fibers used: 1mm to 3mm; The average particle size of the aluminum nitride used: 3 μm; The average particle size of the hexagonal boron nitride used was 3 μm. The fineness of the flake graphite used: 100 mesh; The diameter of the graphene sheets used: 1μm~5μm; The inner diameter of the carbon nanotubes used is 2nm to 5nm, and the length is 10μm to 30μm.

[0069] In the embodiments and comparative examples of this invention, the "epoxy resin mixture" is obtained by mixing E-51 bisphenol A type epoxy resin and 650# polyamide curing agent at a mass ratio of 2:1.

[0070] Example 1 The carbon ceramic disc brake pad provided in this embodiment includes an inner layer and an outer layer, and the raw material composition of each layer is as follows: The inner layer contains the following raw materials in parts by weight: 16 parts carbon fiber, 14 parts basalt fiber, 22 parts blended resin of cashew shell oil modified phenolic resin and polyimide resin, 10 parts flake graphite, and 6 parts aluminum nitride. The outer layer contains the following raw materials in parts by weight: 13 parts carbon fiber, 17 parts basalt fiber, 18 parts blended resin of cashew nut shell oil modified phenolic resin and polyimide resin, 10 parts graphene modified molybdenum disulfide, 3 parts methyltrimethoxysilane, 6 parts hexagonal boron nitride, and 4 parts urea-formaldehyde resin-coated lubricating oil microcapsules.

[0071] The preparation method of graphene-modified molybdenum disulfide is as follows: Graphene and molybdenum disulfide (D50 of 15 μm) were mixed at a mass ratio of 1:3 and then ball-milled. Zirconia grinding balls were added at a ball-to-material ratio of 20:1, and the mixture was ball-milled at 400 rpm for 12 hours under argon protection.

[0072] After ball milling, the mixture was washed three times with anhydrous ethanol and dried under vacuum at 120°C for 24 hours to obtain a mixed powder. The mixed powder was dispersed in anhydrous ethanol at a solid-liquid ratio of 1:10, and then KH-550 silane coupling agent (mass ratio to graphene of 200:1) was added. The mixture was stirred at 70°C for 3 hours, filtered, and dried to obtain graphene-modified molybdenum disulfide.

[0073] The preparation method of the blend resin of cashew nut shell oil modified phenolic resin and polyimide resin is as follows: PR-12686F cashew nut shell oil modified phenolic resin (softening point 95℃) and PL450A polyimide resin (heat distortion temperature 343℃) were dissolved in N,N-dimethylformamide at a mass ratio of 2:1 to prepare a blended resin solution with a total solid content of 35%. The solution was stirred for 3 hours to obtain a blended resin of cashew nut shell oil modified phenolic resin and polyimide resin.

[0074] The preparation method of urea-formaldehyde resin-coated lubricating oil microcapsules is as follows: Urea and 37% formaldehyde solution were mixed at a molar ratio of 1:1.9, and the pH was adjusted to 8.5 with triethanolamine. The mixture was stirred at 75°C for 1 hour to obtain urea-formaldehyde prepolymer.

[0075] The lubricating core material is PAO4 polyalphaolefin synthetic lubricating oil. The lubricating core material, sodium dodecylbenzene sulfonate and deionized water are mixed at a mass ratio of 1:0.02:4 and emulsified at 4000 r / min for 15 min to obtain the core material emulsion.

[0076] Urea-formaldehyde prepolymer was added dropwise to the core material emulsion over a period of 1 hour. The mass ratio of urea-formaldehyde prepolymer to lubricating core material was 0.65:1. The pH was adjusted to 4.5 with a 10% acetic acid solution, and the reaction was carried out at 70°C for 3.5 hours.

[0077] After the reaction was completed, the mixture was centrifuged, washed three times with water and three times with alcohol, and then vacuum dried at 55°C for 24 hours to obtain urea-formaldehyde resin-coated lubricating oil microcapsules.

[0078] The method for preparing carbon ceramic disc brake pads provided in this embodiment is as follows: TC4 titanium alloy steel backing was selected, and the surface was sandblasted (roughness Ra=1.5μm). The raw materials for the inner layer were mixed at 2000 r / min for 50 min, and the mixture was evenly spread on the surface of the steel backing to a thickness of 3.0 mm, and pre-baked at 120℃ for 1.5 h. The raw materials for the outer layer (excluding urea-formaldehyde resin-coated lubricating oil microcapsules) were mixed at 2000 r / min for 60 min, and the mixture was evenly spread on the surface of the inner layer to a thickness of 2.0 mm.

[0079] The laid brake pads are placed in a hot press mold with raised microgrooves on the surface and hot-pressed at 35 MPa and 200℃ for 22 minutes to press out water-guiding microgrooves inclined at 45°, with a groove width of 0.3 mm, a depth of 0.5 mm, and a spacing of 4 mm. After hot pressing, the brake pads are heated to 150℃ at a rate of 2℃ / min and held at that temperature for 2 hours, then heated to 200℃ and held at that temperature for 2 hours, then heated to 250℃ and held at that temperature for 2 hours, and then cooled in the furnace.

[0080] The brake pads were placed in a vacuum impregnation container and kept at 5.5 kPa for 15 min. A mixture of urea-formaldehyde resin-coated lubricating oil microcapsules and epoxy resin was mixed at a mass ratio of 2:1. Anhydrous ethanol was added to adjust the solid content of the mixture to 10%. The mixture was then poured into an impregnation tank to submerge the friction surface of the brake pads, and compressed air was introduced to 0.1 MPa and maintained for 10 min. After draining the slurry, the brake pads were removed, centrifuged at 1000 r / min for 6 min, and dried at 80℃ for 2 h.

[0081] Example 2 The carbon ceramic disc brake pads provided in this embodiment differ from those in Embodiment 1 in that: The inner layer contains the following raw materials in parts by weight: 16 parts carbon fiber, 14 parts basalt fiber, 22 parts blended resin of cashew shell oil modified phenolic resin and polyimide resin, 10 parts flake graphite, and 6 parts aluminum nitride. The outer layer contains the following raw materials in parts by weight: 13 parts carbon fiber, 17 parts basalt fiber, 18 parts blended resin of cashew nut shell oil modified phenolic resin and polyimide resin, 8 parts graphene modified molybdenum disulfide, 2 parts methyltrimethoxysilane, 6 parts hexagonal boron nitride, and 4 parts urea-formaldehyde resin coated lubricating oil microcapsules.

[0082] The preparation method was carried out in accordance with Example 1.

[0083] Example 3 The carbon ceramic disc brake pads provided in this embodiment differ from those in Embodiment 1 in that: The inner layer contains the following raw materials in parts by weight: 16 parts carbon fiber, 14 parts basalt fiber, 22 parts blended resin of cashew nut shell oil modified phenolic resin and polyimide resin, 10 parts flake graphite, and 6 parts aluminum nitride. The outer layer comprises the following raw materials in parts by weight: 13 parts carbon fiber, 17 parts basalt fiber, 18 parts blended resin of cashew nut shell oil modified phenolic resin and polyimide resin, 12 parts graphene modified molybdenum disulfide, 4 parts methyltrimethoxysilane, 6 parts hexagonal boron nitride, and 4 parts urea-formaldehyde resin coated lubricating oil microcapsules.

[0084] The preparation method was carried out in accordance with Example 1.

[0085] Example 4 The carbon ceramic disc brake pads provided in this embodiment differ from those in Embodiment 1 in that: The inner layer contains the following raw materials in parts by weight: 16 parts carbon fiber, 14 parts basalt fiber, 22 parts blended resin of cashew nut shell oil modified phenolic resin and polyimide resin, 10 parts flake graphite, and 6 parts aluminum nitride. The outer layer comprises the following raw materials in parts by weight: 13 parts carbon fiber, 17 parts basalt fiber, 18 parts blended resin of cashew nut shell oil modified phenolic resin and polyimide resin, 10 parts carbon nanotube modified tungsten disulfide, 3 parts methyltrimethoxysilane, 6 parts hexagonal boron nitride, and 4 parts urea-formaldehyde resin coated liquid paraffin microcapsules.

[0086] The preparation method of carbon nanotube-modified tungsten disulfide is as follows: Carbon nanotubes and tungsten disulfide powder were mixed at a mass ratio of 1:3 and then ball-milled. Zirconia grinding balls were added at a ball-to-material ratio of 20:1, and the mixture was ball-milled at 400 rpm for 12 hours under argon protection.

[0087] After ball milling, the mixture was washed three times with anhydrous ethanol and vacuum dried at 120°C for 24 hours to obtain a mixed powder. The mixed powder was dispersed in anhydrous ethanol at a solid-liquid ratio of 1:10, and then KH-550 silane coupling agent (mass ratio of carbon nanotubes to 200:1) was added. The mixture was stirred at 70°C for 3 hours, filtered, and dried to obtain carbon nanotube-modified tungsten disulfide.

[0088] The preparation method of urea-formaldehyde resin-coated liquid paraffin microcapsules is as follows: Urea and 37% formaldehyde solution were mixed at a molar ratio of 1:1.9, and the pH was adjusted to 8.5 with triethanolamine. The mixture was stirred at 75°C for 1 hour to obtain urea-formaldehyde prepolymer.

[0089] The lubricating core material is No. 5 liquid paraffin. The lubricating core material, sodium dodecylbenzene sulfonate and deionized water are mixed at a mass ratio of 1:0.02:4 and emulsified at 4000 r / min for 15 min to obtain the core material emulsion.

[0090] Urea-formaldehyde prepolymer was added dropwise to the core material emulsion over a period of 1 hour. The mass ratio of urea-formaldehyde prepolymer to lubricating core material was 0.65:1. The pH was adjusted to 4.5 with a 10% acetic acid solution, and the reaction was carried out in a 75°C water bath for 3.5 hours.

[0091] After the reaction was completed, the mixture was centrifuged, washed three times with water and three times with alcohol, and then vacuum dried at 55°C for 24 hours to obtain urea-formaldehyde resin-coated liquid paraffin microcapsules.

[0092] The preparation method was carried out in accordance with Example 1.

[0093] Example 5 The carbon ceramic disc brake pads provided in this embodiment differ from those in Embodiment 1 in that: The inner layer contains the following raw materials in parts by weight: 16 parts carbon fiber, 14 parts basalt fiber, and 22 parts blended resin of cashew nut shell oil modified phenolic resin and polyimide resin. The outer layer contains the following raw materials in parts by weight: 13 parts carbon fiber, 17 parts basalt fiber, 18 parts blended resin of cashew nut shell oil modified phenolic resin and polyimide resin, 10 parts graphene modified molybdenum disulfide, and 3 parts methyltrimethoxysilane (excluding urea-formaldehyde resin-coated lubricating oil microcapsules).

[0094] The preparation method was carried out in accordance with Example 1.

[0095] Example 6 The carbon ceramic disc brake pad provided in this embodiment differs from that in embodiment 5 in that: a mold is not used to press the water-guiding micro-groove; instead, the laid brake pad is placed into a hot press mold with a flat surface and hot-pressed at 35MPa and 200℃ for 22 minutes.

[0096] The preparation method was carried out in accordance with Example 5.

[0097] Example 7 The carbon ceramic disc brake pad provided in this embodiment differs from that in Embodiment 5 in that the post-curing treatment conditions are 200°C for 6 hours, that is, the brake pad is heated to 200°C at 2°C / min and held for 6 hours after hot pressing, and then cooled with the furnace.

[0098] The preparation method was carried out in accordance with Example 5.

[0099] Comparative Example 1 The carbon ceramic disc brake pads provided in this comparative example differ from those in Example 5 in that molybdenum disulfide powder is used instead of graphene-modified molybdenum disulfide.

[0100] The preparation method was carried out in accordance with Example 5.

[0101] Comparative Example 2 The carbon ceramic disc brake pads provided in this comparative example differ from those in Example 5 in that tungsten disulfide powder is used instead of graphene-modified molybdenum disulfide.

[0102] The preparation method was carried out in accordance with Example 5.

[0103] Comparative Example 3 The carbon ceramic disc brake pads provided in this comparative example differ from those in Example 5 in that: The inner layer contains the following raw materials in parts by weight: 16 parts carbon fiber, 14 parts basalt fiber, and 22 parts blended resin of cashew nut shell oil modified phenolic resin and polyimide resin. The outer layer contains the following raw materials in parts by weight: 13 parts carbon fiber, 17 parts basalt fiber, 18 parts blended resin of cashew nut shell oil modified phenolic resin and polyimide resin, 10 parts graphene modified molybdenum disulfide, and 6 parts hexagonal boron nitride (excluding methyltrimethoxysilane).

[0104] The preparation method was carried out in accordance with Example 5.

[0105] The performance of the manufactured carbon ceramic disc brake pads was evaluated.

[0106] (1) Friction coefficient test: The test was conducted in accordance with GB / T5763-2018 "Automotive Brake Liners". A 30mm×30mm×8mm sample was cut from the finished brake pad. The friction surface was sanded until smooth, cleaned with alcohol, and then dried. The carbon ceramic brake disc (diameter 280mm) was fixed on the turntable of a constant speed friction testing machine with an environmental chamber. The sample was installed under the pressure arm to ensure that the friction surfaces were completely in contact. The test parameters were set as follows: contact pressure 0.5MPa, sliding speed 4m / s, temperature range -20℃~50℃ (each 5℃ is a test point). Each temperature point was kept warm for 10min~15min, and then the testing machine was started to continuously rub for 5s. The real-time friction force was recorded. After the environmental chamber stabilized at the set temperature, the next temperature point was tested. Each temperature point was tested once. Calculate the coefficient of friction: μ = frictional force / (contact pressure × sample area). Take this test value as the coefficient of friction at that temperature point. Then, calculate the arithmetic mean of the coefficients of friction at all test temperature points to obtain the average coefficient of friction within the temperature range. Simultaneously, calculate the fluctuation value of the coefficient of friction within the temperature range of -20℃ to 50℃. The fluctuation value of the coefficient of friction is the difference between the maximum and minimum values ​​of the coefficient of friction at all test temperature points.

[0107] (2) Wet friction coefficient attenuation rate: Simulate wet working conditions, continuously spray water on the friction surface (spray water volume 2L / min), conduct braking test at 25℃, measure wet friction coefficient, attenuation rate = (dry friction coefficient - wet friction coefficient) / dry friction coefficient × 100%, where the dry friction coefficient is the dry friction coefficient value measured at 25℃ in the above (1) friction coefficient test.

[0108] The evaluation results of each performance are shown in Table 1.

[0109] Table 1 Performance test results of carbon ceramic disc brake pads

[0110] As can be seen from Examples 1-7 in Table 1, within the range of raw materials and contents given in this invention, the prepared carbon ceramic disc brake pads can achieve an average friction coefficient of more than 0.40 in the low temperature range of -20℃ to 50℃ and under wet conditions, with the friction coefficient fluctuation value controlled below 0.06 and the wet friction coefficient attenuation rate ≤10%.

[0111] As can be seen from Table 1 and Example 1: Example 4 shows that graphene-modified molybdenum disulfide and carbon nanotube-modified tungsten disulfide are equivalent in low-temperature lubrication, and urea-formaldehyde resin-coated lubricating oil microcapsules and urea-formaldehyde resin-coated liquid paraffin microcapsules are equivalent in auxiliary lubrication.

[0112] Example 5 shows that the inner layer comprises 16 parts carbon fiber, 14 parts basalt fiber, and 22 parts a blend of cashew nut shell oil-modified phenolic resin and polyimide resin; the outer layer comprises 13 parts carbon fiber, 17 parts basalt fiber, 18 parts a blend of cashew nut shell oil-modified phenolic resin and polyimide resin, 10 parts graphene-modified molybdenum disulfide, and 3 parts methyltrimethoxysilane. This combination achieves an average friction coefficient ≥0.40 and a wet friction coefficient attenuation rate ≤10% in a low-temperature range of -20℃ to 50℃ and under wet conditions. Combined with Examples 1-4, it is evident that adding thermally conductive fillers to the inner layer can further reduce the inner layer temperature and abrasive wear; the additional addition of lubricating microcapsules and hexagonal boron nitride to the outer layer can further improve the average friction coefficient, reduce friction coefficient fluctuations, and improve wear resistance under wet conditions.

[0113] Example 6 shows that the synergy between the water-guiding microchannel and the hydrophobic material enables faster drainage.

[0114] Example 7 uses constant temperature curing, and the friction coefficient fluctuates more, indicating that curing after step temperature increase helps to release internal stress, improve density and thermal stability.

[0115] Comparative Example 1 uses molybdenum disulfide instead of graphene to modify molybdenum disulfide. The average friction coefficient decreases, the fluctuation value increases, and the low-temperature lubrication performance deteriorates, indicating that graphene modification can improve the dispersibility and low-temperature film-forming ability of molybdenum disulfide.

[0116] Comparative Example 2, which used tungsten disulfide instead of graphene to modify molybdenum disulfide, showed a decrease in the average friction coefficient, an increase in fluctuation, and a deterioration in low-temperature lubrication performance, indicating that unmodified tungsten disulfide has poor low-temperature performance. Combined with Example 4, it is shown that modifying tungsten disulfide with carbon nanotubes can effectively improve its low-temperature performance.

[0117] Comparative Example 3 demonstrates that methyltrimethoxysilane plays a crucial role in reducing the attenuation rate of the wet friction coefficient.

[0118] The carbon ceramic disc brake pads of this invention can be widely used in high-end passenger cars, racing cars, special vehicles, and other scenarios equipped with carbon ceramic braking systems. They are also suitable for braking systems of other vehicles with strict braking performance requirements. The preparation method of this invention is mature, the equipment is readily available, and the raw materials can be purchased commercially or prepared using conventional methods, enabling industrial-scale mass production and demonstrating good market application prospects and economic benefits.

[0119] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A carbon ceramic disc brake pad, characterized in that, Including inner and outer layers; The inner layer comprises the following raw materials in parts by weight: 30 parts reinforcing fiber and 20 to 24 parts binder; The outer layer comprises the following raw materials in parts by weight: 30 parts reinforcing fiber, 16 to 20 parts binder, 8 to 12 parts modified disulfide, and 2 to 4 parts methyltrimethoxysilane; The modified disulfide includes at least one of graphene-modified molybdenum disulfide and carbon nanotube-modified tungsten disulfide. The outer friction surface is provided with water-guiding microgrooves.

2. The carbon ceramic disc brake pad according to claim 1, characterized in that, The thickness of the inner layer is 2.5mm to 3.5mm; And / or, the thickness of the outer layer is 1.5mm to 2.5mm; And / or, the reinforcing fibers in the inner layer and the reinforcing fibers in the outer layer each independently include at least one of carbon fiber, basalt fiber, chopped glass fiber, and chopped aramid fiber; And / or, the adhesive in the inner layer and the adhesive in the outer layer are both independently selected from a blend of cashew nut shell oil modified phenolic resin and polyimide resin; And / or, the graphene-modified molybdenum disulfide is prepared by ball milling and mixing graphene and molybdenum disulfide powder, dispersing them in ethanol, adding a silane coupling agent, and heating. And / or, the carbon nanotube modified tungsten disulfide is prepared by ball milling and mixing carbon nanotubes and tungsten disulfide powder, dispersing them in ethanol, adding a silane coupling agent, and heating. And / or, the raw materials for preparing the inner layer also include thermally conductive fillers; And / or, the raw materials for preparing the outer layer also include a synergistic lubricant; And / or, the raw materials for preparing the outer layer also include lubricating microcapsules.

3. The carbon ceramic disc brake pad according to claim 2, characterized in that, The blend of cashew nut shell oil-modified phenolic resin and polyimide resin is prepared by mixing and dissolving cashew nut shell oil-modified phenolic resin, polyimide resin and N,N-dimethylformamide. And / or, the mass ratio of the cashew nut shell oil-modified phenolic resin to the polyimide resin is 1 to 5:1; And / or, the mass ratio of graphene to molybdenum disulfide powder in the graphene-modified molybdenum disulfide is 1:1 to 5; And / or, the silane coupling agent in the graphene-modified molybdenum disulfide accounts for 1% to 3% of the total mass of the graphene and molybdenum disulfide powder; And / or, the mass ratio of carbon nanotubes to tungsten disulfide powder in the carbon nanotube-modified tungsten disulfide is 1:1 to 5; And / or, the silane coupling agent in the carbon nanotube-modified tungsten disulfide accounts for 1% to 3% of the total mass of the carbon nanotubes and tungsten disulfide powder; And / or, the heating temperatures in the graphene-modified molybdenum disulfide and the carbon nanotube-modified tungsten disulfide are both independently 60°C to 80°C. And / or, the thermally conductive filler in the inner layer includes at least one of flake graphite and aluminum nitride; And / or, the synergistic lubricant in the outer layer is hexagonal boron nitride; And / or, the lubricating microcapsules include at least one of urea-formaldehyde resin-coated lubricating oil microcapsules and urea-formaldehyde resin-coated liquid paraffin microcapsules; And / or, the thermally conductive filler in the inner layer is 14 to 18 parts; And / or, the synergistic lubricant in the outer layer is 4 to 8 parts; And / or, the amount of lubricating microcapsules in the outer layer is 2 to 6 parts.

4. The carbon ceramic disc brake pad according to claim 3, characterized in that, The method for preparing the lubricating microcapsules includes: mixing urea and formaldehyde, adjusting the pH to alkaline, and then heating to react to obtain a urea-formaldehyde prepolymer; mixing and emulsifying the lubricating core material, emulsifier, and water to obtain a core material emulsion; and mixing the urea-formaldehyde prepolymer and the core material emulsion, adjusting the pH to acidic, and then heating to react to obtain the final product.

5. The carbon ceramic disc brake pad according to claim 4, characterized in that, The molar ratio of urea to formaldehyde is 1:1.8 to 2; And / or, the alkaline pH value is 8 to 9; And / or, the heating temperature of the urea and formaldehyde is 60℃~80℃; And / or, the acidic pH value is 4 to 5; And / or, the heating temperature of the urea-formaldehyde prepolymer and the core material emulsion is 70℃~80℃; And / or, the lubricating core material is lubricating oil or liquid paraffin; And / or, the emulsifier is sodium dodecylbenzenesulfonate; And / or, the mass ratio of the lubricating core material, emulsifier and water is 1:0.01 to 0.03:3 to 5; And / or, the mass ratio of the urea-formaldehyde prepolymer to the lubricating core material is 0.5 to 0.8:

1.

6. A method for preparing a carbon ceramic disc brake pad as described in any one of claims 1 to 5, characterized in that, Includes the following steps: The raw materials for the inner layer are mixed to form a slurry, which is then coated onto the steel back surface and dried to obtain the inner layer. The raw materials for the outer layer are mixed and spread on the inner layer to form the outer layer. The outer layer is formed by hot pressing, and water-guiding microgrooves are pressed into the friction surface of the outer layer during the hot pressing process. Then, post-curing treatment and vacuum impregnation treatment are carried out in sequence.

7. The method for preparing carbon ceramic disc brake pads according to claim 6, characterized in that, The steel backing is made of TC4 titanium alloy; And / or, the temperature of the hot pressing is 180℃~220℃; And / or, the pressure of the hot pressing is 30MPa to 40MPa; And / or, the hot pressing time is 20 min to 25 min; And / or, the width of the water-guiding microchannels is 0.2mm to 0.4mm, the depth is 0.4mm to 0.6mm, and the spacing is 3mm to 5mm; And / or, the post-curing treatment is a stepped temperature rise curing treatment; And / or, the vacuum impregnation process includes sequentially injecting impregnation slurry and pressurized permeation.

8. The method for preparing carbon ceramic disc brake pads according to claim 7, characterized in that, The heating rate of the solidification process after the stepped heating is 1℃ / min to 3℃ / min; And / or, the step heating and curing process is divided into three insulation sections, including a first insulation section, a second insulation section and a third insulation section; And / or, the vacuum degree during the injection of the impregnation slurry is 5 kPa to 6 kPa; And / or, the pressure of the pressurized permeation is 0.1 MPa to 0.2 MPa; And / or, the pressure holding time for the pressurized permeation is 5 min to 15 min.

9. The method for preparing carbon ceramic disc brake pads according to claim 8, characterized in that, The temperature of the first insulation section is 140℃~160℃; And / or, the temperature of the second insulation section is 180℃~220℃; And / or, the temperature of the third insulation section is 240℃~260℃; And / or, the insulation time of the first insulation section, the second insulation section and the third insulation section are each 1.5h to 2.5h independently; And / or, the impregnation slurry for vacuum impregnation treatment is a mixture of lubricating microcapsules, epoxy resin and ethanol; And / or, the vacuum impregnation process may further include centrifugation and curing.

10. The method for preparing carbon ceramic disc brake pads according to claim 9, characterized in that, The mass ratio of the lubricating microcapsule to the epoxy resin is 2-4:1; And / or, the curing temperature is 70℃~90℃.

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