A brake pad adapted to a carbon ceramic brake disc and a preparation process thereof

Abstract

The present application relates to the technical field of brake pad, and particularly relates to a brake pad matched with a carbon-toughened brake disc and a preparation process thereof, the brake pad is composed of the following components in percentage by weight: reinforcing fiber 25-57%, lubricant 22-49%, binder 7-17%, friction modifier 7.2-28.1%, and filler 3-23%, wherein the reinforcing fiber is at least one of nano-silicon nitride modified ceramic fiber, carbon fiber, and aramid fiber. The components in the present application are matched to make the prepared brake pad have the advantages of good heat conduction, shear resistance and wear resistance, good toughness, noise reduction, stable friction coefficient, reliability at low temperature, strong braking force at high temperature, stable braking, and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of brake pads, in particular to a brake pad matched with a carbon-ceramic brake disc and a preparation process thereof. BACKGROUND

[0002] The carbon-ceramic brake disc has become a core component of the braking system of high-end vehicles due to its advantages of light weight, high temperature resistance, stable friction performance, etc. It can effectively improve the braking response speed and sustained braking capacity of vehicles, and meet the stringent requirements of high-performance driving on the braking system. However, the high efficiency of the carbon-ceramic brake disc is highly dependent on the matched brake pad, and the performance of the brake pad directly affects the braking safety, stability and service life of the carbon-ceramic disc.

[0003] At present, there are two typical problems with brake pads matched with carbon-ceramic brake discs: special carbon-ceramic brake pads can match the performance of carbon-ceramic discs, but they need to be produced by a deposition process, which takes 15-20 days and is very costly, significantly increasing the cost of the vehicle braking system; traditional brake pads have a short production cycle (only about 2 days) and low cost, but due to the extremely high hardness of the carbon-ceramic disc, the traditional brake pads are prone to severe wear, and the hard abrasive ingredients (such as steel fibers and some oxides) contained therein can scratch the surface of the carbon-ceramic disc and damage the structure of the carbon-ceramic disc. In addition, the friction coefficient of the traditional brake pad fluctuates greatly in a wide temperature range, and it is prone to thermal recession at high temperatures, and the high-frequency noise problem unique to the carbon-ceramic system is also difficult to solve. SUMMARY

[0004] In view of the problems in the prior art, the present application provides a brake pad matched with a carbon-ceramic brake disc and a preparation process thereof, so that the prepared brake pad has the advantages of good heat conduction, shear resistance and wear resistance, good toughness, noise reduction, stable friction coefficient, low temperature reliability, high temperature braking force, stable braking and the like.

[0005] To achieve the above object, the technical scheme is as follows:

[0006] The present application discloses a brake pad matched with a carbon-ceramic brake disc, which comprises the following components in percentage by weight: reinforcing fibers 25-57%, lubricant 22-49%, binder 7-17%, friction modifier 7.2-28.1%, and filler 3-23%. The reinforcing fibers are at least one of nano-silicon nitride modified ceramic fiber, carbon fiber and aramid fiber.

[0007] By setting the above technical scheme, the formula improves the structural strength and heat resistance by a high proportion of reinforcing fibers; the lubricant ensures stable friction and reduces wear and noise; the binder ensures the structural integrity at high temperatures; the friction modifier optimizes the friction coefficient; and the filler adjusts the density and cost. The synergistic effect of each component enables the obtained brake pad to be matched with the carbon-ceramic disc, achieving the effects of low wear, high temperature resistance, stable performance and noise reduction.

[0008] Preferably, the composition of the reinforcing fiber, by weight percentage of the total components, is as follows: 14-26% nano-silicon nitride modified ceramic fiber, 5-15% carbon fiber, and 6-16% aramid fiber, wherein the carbon fiber is short-cut fiber with a length of 3-6 mm.

[0009] By employing the aforementioned technical solutions, carbon fiber, with its excellent thermal conductivity, can rapidly conduct the frictional heat generated during braking, preventing localized overheating and enhancing the brake pads' shear resistance, thus reducing wear. Aramid fiber, with its outstanding toughness, can absorb vibration energy generated during braking, effectively suppressing noise while improving the overall toughness of the brake pads. The interwoven nano-silicon nitride modified ceramic fiber, carbon fiber, and aramid fiber form a three-dimensional network structure, which ensures the overall strength of the brake pads while avoiding hard contact with the carbon-ceramic brake disc. The carbon fiber is chopped to 3-6mm, facilitating uniform dispersion, enhancing the brake pads' shear resistance, and providing efficient heat conduction.

[0010] The preferred method for preparing nano-silicon nitride modified ceramic fibers is as follows:

[0011] a1. Add KH-560 to an ethanol-water solution with a volume ratio of 3:1 to prepare a 5% concentration KH-560 ethanol-water solution;

[0012] a2. Place the aluminum silicate fiber in KH-560 ethanol-water solution and stir in a constant temperature water bath at 65-70℃ for 2-2.5h. Then take out the fiber and dry it in an oven at 120-130℃ for 2h to obtain activated fiber.

[0013] a3. Weigh the activated fiber and nano silicon nitride at a mass ratio of 8:2, put them into a high-speed mixer, and stir at a speed of 3500-4000r / min for 30-40min to make the nano silicon nitride uniformly coat the fiber surface.

[0014] a4. Place the mixed fibers in a nitrogen-protected furnace and calcine at 850℃ for 2.5 hours. After cooling, pulverize to 3-7 mm to obtain nano-silicon nitride modified ceramic fibers.

[0015] By setting up the above technical solution, the coating layer formed by nano-silicon nitride on the surface of activated fibers can provide good lubricity and prevent the brake pads from scratching the carbon ceramic brake disc during braking. At the same time, the nano-sized silicon nitride dispersed on the fiber surface enhances the interfacial bonding force between the fibers and other components, and improves the structural stability of the brake pads in high-temperature environments.

[0016] Preferably, the length of the aluminum silicate fiber is 5-10 mm, and the particle size of the nano-silicon nitride is 20-50 nm.

[0017] By setting the above technical solution, the length of the aluminum silicate fiber is 5-10mm. This length can not only ensure that it forms an effective skeleton support in the brake pad matrix and enhance the overall structural strength of the material, but also facilitate uniform mixing with other components. The nano-silicon nitride particles have a diameter of 20-50nm. The small particle size allows it to coat the surface of the aluminum silicate fiber more uniformly, increasing the contact area. This not only enhances the interfacial bonding force between the fiber and other components, but also improves the density and uniformity of the lubricating protective film due to its nanoscale characteristics, reducing hard contact between the fiber and the brake disc.

[0018] Preferably, the lubricant composition, by weight percentage of total components, is as follows: 8-18% graphene composite lubricating particles, 13-23% composite graphite, and 1-8% antimony sulfide;

[0019] The preparation method of graphene composite lubricating particles is as follows:

[0020] b1. Weigh natural graphite, graphene, and molybdenum disulfide in a mass ratio of 6:1:3, put them into a ball mill, and ball mill them at a speed of 250 r / min for 1.5 h. Then add a modified phenolic resin solution accounting for 12% of the total solid mass and stir until a uniform paste is formed.

[0021] b2. Spray granulation of the obtained paste, with the inlet temperature set to 200℃ and the outlet temperature set to 90℃, to obtain particles with a particle size of 60-120μm. Then, place the particles in a nitrogen atmosphere and cure at 210-220℃ for 2-2.5h to obtain graphene composite lubricating particles.

[0022] By setting up the above technical solutions, antimony sulfide can improve the stability of the friction coefficient in high-temperature environments, ensuring that the brake pads still have strong braking force at high temperatures; graphene has excellent lubrication properties and can enhance the continuity of the lubrication film; natural graphite provides basic lubrication; molybdenum disulfide can enhance the lubrication effect under high load conditions. The three work together to achieve stable lubrication over a wide temperature range.

[0023] Preferably, the natural graphite has a particle size of 5-10 μm; the graphene is a single layer with a particle size of 0.5-2 μm; the molybdenum disulfide has a particle size of 1-3 μm; and the modified phenolic resin is a modified phenolic resin with active groups such as rubber, cashew nut shell oil, and epoxy resin introduced into it, and the modified phenolic resin is dissolved in a 50% ethanol solution to form a modified phenolic resin solution.

[0024] By setting up the above technical solutions, the particle size of natural graphite, graphene, and molybdenum disulfide can be controlled to achieve uniform dispersion and enhance the lubrication and friction reduction effect. The introduction of active groups into the modified phenolic resin can improve its compatibility with other components and the toughness of the material. Its solubility in ethanol solution facilitates mixing and dispersion, ensuring the stability of the material performance.

[0025] Preferably, the composite graphite is made by uniformly mixing flake graphite and expanded graphite at a mass ratio of 2:1, wherein the particle size of the flake graphite is 5-20 μm and the particle size of the expanded graphite is 10-50 μm.

[0026] By employing the aforementioned technical solution, flake graphite exhibits excellent lubrication continuity and stability, providing basic lubrication at room temperature. Expanded graphite, on the other hand, expands at high temperatures (typically above 200°C) to form a dense protective layer, reducing direct friction between the brake pads and the carbon-ceramic brake disc, while simultaneously filling the microscopic pores on the friction surface. A 2:1 mixing ratio achieves a balance of lubrication performance across a wide temperature range. If the particle size difference between flake graphite and expanded graphite is too large (e.g., flake graphite above 100μm, expanded graphite below 10μm), stratification is likely to occur during mixing, leading to localized lubrication imbalances and affecting the frictional stability of the brake pads. The similar particle size range of both avoids stratification during mixing, ensuring compatibility with the friction surface of the carbon-ceramic brake disc, preventing scratches or frictional vibrations, thereby forming a continuous and stable lubricating film and improving the frictional stability of the brake pads.

[0027] Preferably, the adhesive is a multiphase gradient adhesive, and its preparation method is as follows:

[0028] c1. Weigh cashew nut shell oil modified phenolic resin, polyether ether ketone, and nitrile rubber powder according to a mass ratio of 6:3:1, add them to a twin-screw extruder, set the temperature of zone 1 to 130℃, zone 2 to 160℃, zone 3 to 190℃, and the screw speed to 250r / min, and carry out melt blending.

[0029] c2. The extrudate obtained in c1 is cut into 3-5 mm particles by a pelletizer, dried in a vacuum drying oven at 78-80℃ for 4.5-5 h, and then frozen in an environment at -30℃ for 3 h. After that, it is taken out and placed at room temperature to complete the temperature shock modification, thus obtaining a multiphase gradient binder.

[0030] By setting the above technical solution, the limitation of the melt blending step enables the three raw materials to be uniformly compounded, laying the foundation for the graded properties of the binder; cutting the extrudate into 3-5mm particles and vacuum drying at 78-80℃ for 4.5-5h can effectively remove moisture and volatiles, ensuring the stability of the particle state; while the temperature shock modification after freezing at -30℃ for 3h and then restoring to room temperature can optimize the internal stress distribution and interfacial bonding force of the material, ultimately forming a multiphase graded binder that can play a dominant role in different temperature ranges. Moreover, the granular form is convenient to be directly added as a raw material to the mixing process of brake pad preparation, ensuring that it is uniformly dispersed with other components and fully exerts its bonding effect.

[0031] Preferably, the friction modifier comprises the following components by weight percentage: 3-13% potassium titanate whiskers, 4-14% cashew nut shell oil friction powder, and 0.2-1.1% ultrafine tin powder, wherein the particle size of the ultrafine tin powder is 3-5 μm.

[0032] The filler consists of the following components: 2-12% barite powder and 1-11% barium sulfate.

[0033] By employing the aforementioned technical solutions, potassium titanate whiskers, with their needle-like structure, enhance the structural strength of the brake pads, adjust the coefficient of friction, and provide noise reduction. Cashew nutshell oil friction powder improves the friction performance of the brake pads at low temperatures, making low-temperature braking more reliable and reducing noise during braking. Ultrafine tin powder particles, with their small size, fill the microscopic voids in the friction surface, improving the contact state, reducing friction fluctuations, and resulting in smoother braking. The ultrafine tin powder, with a particle size of 3-5 μm, fills the voids in the friction surface, improving the contact state and reducing friction fluctuations. Barite powder and barium sulfate, as inert fillers, adjust the density of the brake pads and help stabilize the coefficient of friction. The combined effect of these components gives the resulting brake pads advantages such as good thermal conductivity, shear resistance, wear resistance, high toughness, noise reduction, stable coefficient of friction, low-temperature reliability, strong high-temperature braking force, and smooth braking.

[0034] This application also discloses a manufacturing process for brake pads based on adaptive carbon ceramic brake discs, comprising the following steps:

[0035] S1. Take nano-silicon nitride modified ceramic fiber, carbon fiber and aramid fiber according to the proportion, dry them in an oven at 80℃ for 3 hours, cool them to room temperature and then add them to a high-speed mixer. Stir at 1100-1200r / min for 12-15 minutes to make the fibers disperse evenly.

[0036] S2. Add the pre-softened multiphase gradient binder to the mixed fibers, adjust the speed to 1450-1500 r / min, and stir for 18-20 min. Then, add graphene composite lubricating particles, composite graphite, potassium titanate whiskers, cashew shell oil friction powder, antimony sulfide, barite powder, barium sulfate, and ultrafine tin powder in sequence, and stir at 1700-1800 r / min for 25-30 min. Stop the machine every 5 min to clean the mixing tank wall to ensure uniform mixing.

[0037] S3. Preheat the brake pad preparation mold to 80℃, load the mixed material from S2 into the mold, apply a pressure of 7.5-8MPa for 3-4 minutes, then increase the pressure to 20-22MPa and hold the pressure for 10-12 minutes.

[0038] S4. Perform a stepped solidification process on the material inside the mold in S3:

[0039] Phase 1: Keep warm at 125-130℃ for 1.5-2 hours;

[0040] Phase Two: Raise the temperature to 175-180℃ and maintain the temperature for 2-2.5 hours;

[0041] Phase 3: Raise the temperature to 215-220℃ and maintain the temperature for 2-2.5 hours;

[0042] It was then cooled to room temperature at a rate of 5°C / min.

[0043] S5. Grind the surface of the cured brake pads to achieve a surface roughness Ra of 1.6-3.2μm. Finally, place them in an oven at 200℃ for secondary curing for 3.5-4 hours to remove residual volatiles, thus obtaining brake pads suitable for carbon ceramic brake discs.

[0044] By setting up the above technical solutions, this process ensures uniform bonding of raw materials through fiber drying and dispersion, step-by-step high-speed mixing, segmented pre-compression to increase density, step-curing and controlled cooling to reduce internal stress, and surface treatment and secondary curing to optimize performance. The resulting brake pads have a stable structure and good friction surface compatibility, and can be adapted to carbon ceramic brake discs, ensuring braking performance.

[0045] The beneficial effects of this invention are as follows:

[0046] Nano-silicon nitride modified ceramic fibers, carbon fibers, and aramid fibers intertwine to form a three-dimensional network structure. This structure ensures the overall strength of the brake pads while avoiding hard contact with the carbon-ceramic brake disc. Graphene composite lubricating particles uniformly fill the pores of this three-dimensional network. During braking, these lubricating particles simultaneously release lubricating components, forming a structure of "high-strength skeleton + adaptive lubrication film." This structure allows the brake pads to maintain a relatively high coefficient of friction (0.42-0.46) while also achieving a low wear rate.

[0047] Cashew nutshell oil-modified phenolic resin ensures the bonding strength of the brake pads at room temperature; polyetheretherketone (PEEK) enhances the structural strength of the material at high temperatures; and nitrile rubber powder strengthens the toughness of the binder, enabling the brake pads to better resist impacts during braking. Furthermore, the multiphase gradient binder plays a dominant role in different temperature ranges: at low temperatures (<200℃), cashew nutshell oil-modified phenolic resin ensures good bonding performance; at medium temperatures (200-400℃), PEEK maintains the structural strength of the material; and at high temperatures (>400℃), the elasticity of nitrile rubber buffers stress. This temperature-responsive characteristic, combined with the "temperature-response release" characteristic of graphene composite lubricating particles, results in a friction coefficient fluctuation of ≤0.02 within the temperature range of 100-600℃, far superior to the friction coefficient fluctuation >0.05 in traditional formulations.

[0048] Aramid fibers and cashew nutshell oil friction powder together form an elastic buffer layer that can absorb more than 60% of frictional vibration energy, effectively reducing noise. The needle-like structure of potassium titanate whiskers can disperse the stress generated during braking, preventing localized wear from worsening. Through synergistic effects, the peak noise level of the brake pads is controlled below 65dB, while the wear rate of the brake pads is reduced by 40%, and the wear rate of the carbon ceramic brake discs is reduced by more than 70%.

[0049] Flake graphite exhibits excellent lubrication continuity and stability, providing basic lubrication at room temperature; expanded graphite, on the other hand, expands at high temperatures (typically above 200°C) to form a dense protective layer, reducing direct friction between the brake pads and the carbon-ceramic brake disc, while simultaneously filling the microscopic pores on the friction surface. By mixing them in a 2:1 ratio, a balance of lubrication performance can be achieved over a wide temperature range. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0051] Example 1: This example discloses a brake pad adapted to a carbon ceramic brake disc. The brake pad's composition, by weight percentage, is as follows: 26% nano-silicon nitride modified ceramic fiber, 8% graphene composite lubricating particles, 7% multiphase gradient binder, 10.8% carbon fiber, 6% aramid fiber, 13% composite graphite, 9% potassium titanate whiskers, 6% cashew nutshell oil friction powder, 8% antimony sulfide, 3% barite powder, 3% barium sulfate, and 0.2% ultrafine tin powder. The composite graphite is a uniform mixture of flake graphite and expanded graphite at a mass ratio of 2:1. The flake graphite has a particle size of 5 μm, and the expanded graphite has a particle size of 10 μm. The carbon fiber is a short-cut fiber with a length of 3 mm. The ultrafine tin powder has a particle size of 3 μm.

[0052] The preparation method of nano-silicon nitride modified ceramic fibers is as follows:

[0053] a1. Add KH-560 to an ethanol-water solution with a volume ratio of 3:1 to prepare a 5% concentration KH-560 ethanol-water solution;

[0054] a2. Place 5mm long aluminum silicate fibers into KH-560 ethanol-water solution and stir in a constant temperature water bath at 65℃ for 2 hours. Then remove the fibers and dry them in an oven at 120℃ for 2 hours to obtain activated fibers.

[0055] a3. Weigh the activated fiber and 20nm nano silicon nitride at a mass ratio of 8:2, put them into a high-speed mixer, and stir at 3500r / min for 30min to make the nano silicon nitride uniformly coat the fiber surface.

[0056] a4. Place the mixed fibers in a nitrogen-protected furnace and calcine at 850℃ for 2.5 hours. After cooling, pulverize to 3 mm to obtain nano-silicon nitride modified ceramic fibers.

[0057] The preparation method of graphene composite lubricating particles is as follows:

[0058] b1. Weigh out natural graphite with a particle size of 5μm, graphene with a single-layer particle size of 0.5μm, and molybdenum disulfide with a particle size of 1μm in a mass ratio of 6:1:3, put them into a ball mill, and ball mill them at a speed of 250r / min for 1.5h. Then add a modified phenolic resin solution accounting for 12% of the total solid mass and stir until a uniform paste is formed.

[0059] Among them, the modified phenolic resin is a modified phenolic resin with active groups such as rubber, cashew shell oil, and epoxy resin introduced, and the modified phenolic resin is dissolved in a 50% ethanol solution to form a modified phenolic resin solution.

[0060] b2. Spray granulation of the obtained paste, with the inlet temperature set at 200℃ and the outlet temperature set at 90℃, to obtain particles with a particle size of 60μm. Then, the particles are placed in a nitrogen atmosphere and cured at 210℃ for 2 hours to obtain graphene composite lubricating particles.

[0061] The preparation method of multiphase gradient adhesive is as follows:

[0062] c1. Weigh cashew nut shell oil modified phenolic resin, polyether ether ketone, and nitrile rubber powder according to a mass ratio of 6:3:1, add them to a twin-screw extruder, set the temperature of zone 1 to 130℃, zone 2 to 160℃, zone 3 to 190℃, and the screw speed to 250r / min, and carry out melt blending.

[0063] c2. The extrudate obtained in c1 is cut into 3mm particles by a pelletizer, dried in a vacuum drying oven at 78℃ for 4.5h, and then frozen in an environment at -30℃ for 3h. After that, it is taken out and placed at room temperature to complete the temperature shock modification, thus obtaining a multiphase gradient binder.

[0064] This embodiment also discloses a manufacturing process for brake pads adapted to carbon ceramic brake discs, including the following steps:

[0065] S1. Take nano-silicon nitride modified ceramic fiber, carbon fiber and aramid fiber according to the proportion, dry them in an oven at 80℃ for 3 hours, cool them to room temperature and then add them to a high-speed mixer. Stir at 1100r / min for 12 minutes to make the fibers disperse evenly.

[0066] S2. Add the pre-softened multiphase gradient binder to the mixed fibers, adjust the speed to 1450 r / min, stir for 18 min, then add graphene composite lubricating particles, composite graphite, potassium titanate whiskers, cashew shell oil friction powder, antimony sulfide, barite powder, barium sulfate, and ultrafine tin powder in sequence, stir at 1700 r / min for 25 min, stop the machine every 5 min to clean the mixing tank wall to ensure uniform mixing;

[0067] S3. Preheat the brake pad preparation mold to 80°C, load the mixed material from S2 into the mold, apply a pressure of 7.5MPa for 3 minutes, then increase the pressure to 20MPa and hold for 10 minutes.

[0068] S4. Perform a stepped solidification process on the material inside the mold in S3:

[0069] Phase 1: Keep warm at 125℃ for 1.5 hours;

[0070] Phase Two: Heat to 175℃ and hold for 2 hours;

[0071] Phase 3: Heat to 215℃ and hold for 2 hours;

[0072] It was then cooled to room temperature at a rate of 5°C / min.

[0073] S5. After curing, the brake pads are surface-ground to achieve a surface roughness Ra of 1.6μm. Finally, they are placed in an oven at 200℃ for a second curing of 3.5h to remove residual volatiles, thus obtaining brake pads suitable for carbon ceramic brake discs.

[0074] Example 2: This example discloses a brake pad adapted to a carbon ceramic brake disc. The brake pad's composition, by weight percentage, is as follows: 14% nano-silicon nitride modified ceramic fiber, 18% graphene composite lubricating particles, 17% multiphase gradient binder, 5% carbon fiber, 12% aramid fiber, 21.9% composite graphite, 3% potassium titanate whiskers, 4% cashew nutshell oil friction powder, 1% antimony sulfide, 2% barite powder, 1% barium sulfate, and 1.1% ultrafine tin powder. The composite graphite is a uniform mixture of flake graphite and expanded graphite at a mass ratio of 2:1. The flake graphite has a particle size of 20 μm, and the expanded graphite has a particle size of 50 μm. The carbon fiber is a short-cut fiber with a length of 6 mm. The ultrafine tin powder has a particle size of 5 μm.

[0075] The preparation method of nano-silicon nitride modified ceramic fibers is as follows:

[0076] a1. Add KH-560 to an ethanol-water solution with a volume ratio of 3:1 to prepare a 5% concentration KH-560 ethanol-water solution;

[0077] a2. Place 10mm long aluminum silicate fibers into KH-560 ethanol-water solution and stir in a constant temperature water bath at 70℃ for 2.5h. Then take out the fibers and dry them in an oven at 130℃ for 2h to obtain activated fibers.

[0078] a3. Weigh the activated fiber and 50nm nano silicon nitride at a mass ratio of 8:2, put them into a high-speed mixer, and stir at 4000r / min for 40min to make the nano silicon nitride uniformly coat the fiber surface.

[0079] a4. Place the mixed fibers in a nitrogen-protected furnace and calcine at 850℃ for 2.5 hours. After cooling, pulverize to 7 mm to obtain nano-silicon nitride modified ceramic fibers.

[0080] The preparation method of graphene composite lubricating particles is as follows:

[0081] b1. Weigh out natural graphite with a particle size of 10μm, graphene with a single-layer particle size of 2μm, and molybdenum disulfide with a particle size of 3μm in a mass ratio of 6:1:3, put them into a ball mill, and ball mill them at a speed of 250r / min for 1.5h. Then add a modified phenolic resin solution accounting for 12% of the total solid mass and stir until a uniform paste is formed.

[0082] Among them, the modified phenolic resin is a modified phenolic resin with active groups such as rubber, cashew shell oil, and epoxy resin introduced, and the modified phenolic resin is dissolved in a 50% ethanol solution to form a modified phenolic resin solution.

[0083] b2. Spray granulation of the obtained paste, with the inlet temperature set to 200℃ and the outlet temperature set to 90℃, to obtain particles with a particle size of 120μm. Then, the particles are placed in a nitrogen atmosphere and cured at 220℃ for 2.5h to obtain graphene composite lubricating particles.

[0084] The preparation method of multiphase gradient adhesive is as follows:

[0085] c1. Weigh cashew nut shell oil modified phenolic resin, polyether ether ketone, and nitrile rubber powder according to a mass ratio of 6:3:1, add them to a twin-screw extruder, set the temperature of zone 1 to 130℃, zone 2 to 160℃, zone 3 to 190℃, and the screw speed to 250r / min, and carry out melt blending.

[0086] c2. The extrudate obtained in c1 is cut into 5mm particles by a pelletizer, dried in a vacuum drying oven at 80℃ for 5h, and then frozen in an environment at -30℃ for 3h. After that, it is taken out and placed at room temperature to complete the temperature shock modification, thus obtaining a multiphase gradient binder.

[0087] This embodiment also discloses a manufacturing process for brake pads adapted to carbon ceramic brake discs, including the following steps:

[0088] S1. Take nano-silicon nitride modified ceramic fiber, carbon fiber and aramid fiber according to the proportion, dry them in an oven at 80℃ for 3 hours, cool them to room temperature and then add them to a high-speed mixer. Stir at 1200r / min for 15 minutes to make the fibers disperse evenly.

[0089] S2. Add the pre-softened multiphase gradient binder to the mixed fibers, adjust the speed to 1500 r / min, stir for 20 min, then add graphene composite lubricating particles, composite graphite, potassium titanate whiskers, cashew shell oil friction powder, antimony sulfide, barite powder, barium sulfate, and ultrafine tin powder in sequence, stir at 1800 r / min for 30 min, stop the machine every 5 min to clean the mixing tank wall to ensure uniform mixing;

[0090] S3. Preheat the brake pad preparation mold to 80°C, load the mixed material from S2 into the mold, apply a pressure of 8MPa for 4 minutes, then increase the pressure to 22MPa and hold for 12 minutes.

[0091] S4. Perform a stepped solidification process on the material inside the mold in S3:

[0092] Phase 1: Keep warm at 130℃ for 2 hours;

[0093] Phase Two: Heat to 180℃ and hold for 2.5 hours;

[0094] Phase 3: Heat to 220℃ and maintain the temperature for 2.5 hours;

[0095] It was then cooled to room temperature at a rate of 5°C / min.

[0096] S5. After curing, the brake pads are surface-ground to achieve a surface roughness Ra of 3.2μm. Finally, they are placed in an oven at 200℃ for a second curing for 4 hours to remove residual volatiles, thus obtaining brake pads suitable for carbon ceramic brake discs.

[0097] Example 3: This example discloses a brake pad adapted to a carbon ceramic brake disc. The brake pad's composition, by weight percentage, is as follows: 18% nano-silicon nitride modified ceramic fiber, 11% graphene composite lubricating particles, 12% multiphase gradient binder, 9% carbon fiber, 10% aramid fiber, 15% composite graphite, 7% potassium titanate whiskers, 7% cashew nutshell oil friction powder, 4% antimony sulfide, 4% barite powder, 2.5% barium sulfate, and 0.5% ultrafine tin powder. The composite graphite is a uniform mixture of flake graphite and expanded graphite at a mass ratio of 2:1. The flake graphite has a particle size of 10 μm, and the expanded graphite has a particle size of 30 μm. The carbon fiber is a short-cut fiber with a length of 4 mm. The ultrafine tin powder has a particle size of 4 μm.

[0098] The preparation method of nano-silicon nitride modified ceramic fibers is as follows:

[0099] a1. Add KH-560 to an ethanol-water solution with a volume ratio of 3:1 to prepare a 5% concentration KH-560 ethanol-water solution;

[0100] a2. Place 7mm long aluminum silicate fibers into KH-560 ethanol-water solution and stir in a constant temperature water bath at 67℃ for 2.2h. Then remove the fibers and dry them in an oven at 125℃ for 2h to obtain activated fibers.

[0101] a3. Weigh the activated fiber and 35nm nano silicon nitride at a mass ratio of 8:2, put them into a high-speed mixer, and stir at 3700r / min for 35min to make the nano silicon nitride uniformly coat the fiber surface.

[0102] a4. Place the mixed fibers in a nitrogen-protected furnace and calcine at 850℃ for 2.5 hours. After cooling, pulverize to 5 mm to obtain nano-silicon nitride modified ceramic fibers.

[0103] The preparation method of graphene composite lubricating particles is as follows:

[0104] b1. Weigh natural graphite with a particle size of 7μm, graphene with a single-layer particle size of 1μm, and molybdenum disulfide with a particle size of 2μm according to a mass ratio of 6:1:3. Put them into a ball mill and ball mill at a speed of 250r / min for 1.5h. Then add a modified phenolic resin solution accounting for 12% of the total solid mass and stir until a uniform paste is formed.

[0105] Among them, the modified phenolic resin is a modified phenolic resin with active groups such as rubber, cashew shell oil, and epoxy resin introduced, and the modified phenolic resin is dissolved in a 50% ethanol solution to form a modified phenolic resin solution.

[0106] b2. Spray granulation of the obtained paste, with the inlet temperature set to 200℃ and the outlet temperature set to 90℃, to obtain particles with a particle size of 90μm. Then, the particles are placed in a nitrogen atmosphere and cured at 215℃ for 2h to obtain graphene composite lubricating particles.

[0107] The preparation method of multiphase gradient adhesive is as follows:

[0108] c1. Weigh cashew nut shell oil modified phenolic resin, polyether ether ketone, and nitrile rubber powder according to a mass ratio of 6:3:1, add them to a twin-screw extruder, set the temperature of zone 1 to 130℃, zone 2 to 160℃, zone 3 to 190℃, and the screw speed to 250r / min, and carry out melt blending.

[0109] c2. The extrudate obtained in c1 is cut into 4mm particles by a pelletizer, dried in a vacuum drying oven at 79℃ for 4.7h, and then frozen in an environment at -30℃ for 3h. After being taken out and placed at room temperature, temperature shock modification is completed to obtain a multiphase gradient binder.

[0110] This embodiment also discloses a manufacturing process for brake pads adapted to carbon ceramic brake discs, including the following steps:

[0111] S1. Take nano-silicon nitride modified ceramic fiber, carbon fiber and aramid fiber according to the proportion, dry them in an oven at 80℃ for 3 hours, cool them to room temperature and then add them to a high-speed mixer. Stir at 1150r / min for 13 minutes to make the fibers disperse evenly.

[0112] S2. Add the pre-softened multiphase gradient binder to the mixed fibers, adjust the speed to 1470 r / min, stir for 19 min, then add graphene composite lubricating particles, composite graphite, potassium titanate whiskers, cashew shell oil friction powder, antimony sulfide, barite powder, barium sulfate, and ultrafine tin powder in sequence, stir at 1750 r / min for 27 min, stop the machine every 5 min to clean the mixing tank wall to ensure uniform mixing;

[0113] S3. Preheat the brake pad preparation mold to 80°C, load the mixed material from S2 into the mold, apply a pressure of 7.7 MPa for 3.5 min, then increase the pressure to 21 MPa and hold for 11 min.

[0114] S4. Perform a stepped solidification process on the material inside the mold in S3:

[0115] Phase 1: Incubate at 127℃ for 1.7 hours;

[0116] Phase Two: Heat to 177℃ and hold for 2 hours;

[0117] Phase 3: Heat to 217℃ and maintain the temperature for 2 hours;

[0118] It was then cooled to room temperature at a rate of 5°C / min.

[0119] S5. After curing, the brake pads are surface-ground to achieve a surface roughness Ra of 2.5μm. Finally, they are placed in an oven at 200℃ for a second curing of 3.5h to remove residual volatiles, thus obtaining brake pads suitable for carbon ceramic brake discs.

[0120] Comparative Example 1:

[0121] A brake pad adapted to carbon ceramic brake discs, the only difference between this brake pad and Example 3 is that ordinary ceramic fibers are used instead of nano-silicon nitride modified ceramic fibers.

[0122] Comparative Example 2:

[0123] A brake pad adapted to carbon ceramic brake discs, the only difference between this brake pad and Example 3 is that an equal amount of flake graphite is used instead of graphene composite lubricating particles.

[0124] Comparative Example 3:

[0125] A brake pad adapted to a carbon ceramic brake disc, the only difference between this brake pad and Example 3 is that ordinary phenolic resin is used instead of the multiphase gradient binder.

[0126] Comparative Example 4:

[0127] A brake pad adapted to a carbon ceramic brake disc, the only difference between this brake pad and Example 3 is that: no carbon fiber is added, and an equal amount of ceramic fiber is used instead.

[0128] Comparative Example 5:

[0129] A brake pad adapted to a carbon ceramic brake disc, the only difference between this brake pad and Example 3 is that: no aramid fiber is added, and an equal amount of carbon fiber is used instead.

[0130] Comparative Example 6:

[0131] A brake pad adapted to a carbon ceramic brake disc, the only difference between this brake pad and Example 3 is that the composite graphite uses only flake graphite (excluding expanded graphite).

[0132] Comparative Example 7:

[0133] A brake pad adapted to a carbon ceramic brake disc, the only difference between this brake pad and Example 3 is that potassium titanate whiskers are not added.

[0134] Comparative Example 8:

[0135] A brake pad adapted to carbon ceramic brake discs, the only difference between this brake pad and Example 3 is that the amount of antimony sulfide is adjusted to 0.2%.

[0136] Comparative Example 9:

[0137] A brake pad adapted to carbon ceramic brake discs, the only difference between this brake pad and Example 3 is that in process S3, the pre-compression is not performed using segmented pressure (direct 22 MPa).

[0138] Comparative Example 10:

[0139] A brake pad adapted to carbon ceramic brake discs, the only difference between this brake pad and Example 3 is that the maximum step curing temperature is 180°C.

[0140] Comparative Example 11:

[0141] A brake pad adapted to carbon ceramic brake discs, the only difference between this brake pad and Example 3 is that the nano-silicon nitride modified ceramic fibers are not coated with silicon nitride (they have undergone activation treatment, but have not undergone nano-silicon nitride coating and subsequent calcination treatment, that is, the fiber surface lacks a nano-silicon nitride coating layer).

[0142] Comparative Example 12:

[0143] A brake pad adapted to carbon ceramic brake discs, the only difference between this brake pad and Example 3 is that all components are mixed in a single step during the preparation process.

[0144] The brake pads obtained in Examples 1-3 and Comparative Examples 1-12 were subjected to performance tests for friction coefficient, wear rate, heat fade, and noise, wherein:

[0145] 1. Friction coefficient test

[0146] Reference standard: GB / T5763-2018 "Automotive Brake Liners"

[0147] Experimental steps:

[0148] 1) Cut a 30mm×30mm×8mm sample from the finished brake pad, sand the friction surface with sandpaper until it is flat, clean it with alcohol and let it dry.

[0149] 2) Fix the carbon ceramic brake disc (280mm in diameter) on the turntable of the constant speed friction tester, and install the sample under the pressure arm to ensure that the friction surfaces are completely in contact.

[0150] 3) Set the test parameters: contact pressure 0.5MPa, sliding speed 4m / s, temperature range 100-500℃ (each 50℃ is a test point).

[0151] 4) Hold each temperature point for 10 minutes, then start the testing machine and rub continuously for 20 seconds. Record the real-time friction force. Repeat the test 3 times for each temperature point.

[0152] 5) Calculate the friction coefficient: μ = friction force ÷ (contact pressure × sample area). Take the average value of 3 tests as the friction coefficient at this temperature point, and at the same time calculate the fluctuation value of the friction coefficient across the entire temperature range (maximum value - minimum value).

[0153] 2. Wear Rate Test

[0154] Reference: ISO 6310:2012 "Road vehicles - Test method for brake pad wear"

[0155] Experimental steps:

[0156] 1) Weigh the initial mass of the brake pad sample (accurate to 0.001g) and measure the initial thickness of the carbon ceramic brake disc using a laser thickness gauge (take the average value of 3 points).

[0157] 2) Install the sample and carbon ceramic disc on the brake test bench and set the simulated working conditions: vehicle speed 40-60km / h, braking deceleration 2.5m / s², braking interval 40s, and a total of 800 cycles.

[0158] 3) After the test, clean the abrasive particles on the sample and the surface of the carbon ceramic disc with alcohol, and weigh and measure the thickness again after drying.

[0159] 4) Calculate the wear rate:

[0160] Brake pad wear rate = (initial mass - mass after test) ÷ total braking work (unit: g / J)

[0161] Wear rate of carbon ceramic disc = (initial average thickness - average thickness after test) ÷ total braking power (unit: mm / J).

[0162] 3. Thermal decay performance test

[0163] Reference standard: GB / T34346-2017 "Test Methods for High-Temperature Performance of Automotive Brake Friction Materials"

[0164] Experimental steps:

[0165] 1) The friction coefficient μ1 at room temperature (25℃) was measured according to the friction coefficient test method.

[0166] 2) Place the brake pad sample into a high-temperature furnace and hold it at 550°C for 25 minutes. Immediately remove it and install it onto a carbon ceramic plate that has been preheated to 550°C.

[0167] 3) Test the coefficient of friction μ2 at 550℃ with the same parameters.

[0168] 4) Calculate the thermal degradation rate: (μ2÷μ1)×100%.

[0169] 4. Noise Test

[0170] Reference: SAE J2521:2019 "Noise Measurement Method for Brake Pads and Disc Assemblies"

[0171] Experimental steps:

[0172] 1) Fix the braking system with brake pads and carbon ceramic discs on a test bench in a semi-anechoic chamber (background noise ≤25dB).

[0173] 2) Place a sound level meter (frequency range 100-8000Hz) 1.2m away from the brake disc and align it with the center of the friction area.

[0174] 3) Set the braking pressure gradient: 0.3MPa, 0.5MPa, 0.7MPa, brake 15 times at each pressure, each braking lasts 3 seconds, with an interval of 10 seconds.

[0175] 4) Record the peak noise level for each braking action and calculate the percentage of times the noise level is ≥80dB (noise occurrence rate).

[0176] The results are shown in Table 1.

[0177] Table 1 Performance parameters of brake pads obtained in Examples 1-3 and Comparative Examples 1-12

[0178]

[0179] As can be seen from Table 1 and Example 3:

[0180] In Comparative Example 1, the average coefficient of friction decreased by 28.3%, while the wear rate of the carbon ceramic disc increased by 286.4%. This may be because the smooth surface of ordinary ceramic fibers results in weak bonding with the matrix, making them prone to detachment and becoming abrasive particles during braking, thus exacerbating the wear of the carbon ceramic disc. In contrast, the nano-silicon nitride modified layer enhances interfacial bonding through chemical bonding, while simultaneously utilizing the low hardness of silicon nitride to form a lubricating protective film, reducing hard contact wear.

[0181] In Comparative Example 2, the friction coefficient fluctuation increased by 305.6%, and the noise occurrence rate increased by 725%. This may be because the interlayer slip properties of graphene in the graphene composite lubricating particles can fill microscopic depressions on the friction surface, resulting in more uniform contact. Replacing the graphene composite lubricating particles with an equal amount of flake graphite resulted in insufficient lubrication continuity from the flake graphite, leading to increased frictional vibration and a surge in noise.

[0182] In Comparative Example 3, the thermal degradation rate decreased by 27.2%, while the brake pad wear rate increased by 180%. This may be because ordinary phenolic resin begins to decompose and become embrittled above 300℃, leading to structural collapse at high temperatures; the PEEK component in the multiphase gradient binder maintains strength at high temperatures, and the nitrile rubber buffers stress, allowing the brake pad to maintain a stable structure even at 550℃.

[0183] In Comparative Example 4, the coefficient of friction decreased by 30.4%, and the thermal degradation rate decreased by 25%. This may be because the high thermal conductivity of carbon fiber can quickly disperse frictional heat, avoiding friction coefficient decay caused by localized high temperatures; without the addition of carbon fiber, heat is concentrated on the friction surface, which accelerates the failure of lubricating components and leads to significant thermal degradation.

[0184] In Comparative Example 5, the peak noise level increased by 27.7%, and the brake pad wear rate increased by 136%. This may be because the high toughness of aramid fibers can absorb braking vibration energy and enhance the material's tear resistance; without aramid fibers, the material becomes more brittle, easily generating high-frequency vibrations during friction, and the surface material is more prone to peeling off, exacerbating wear.

[0185] In Comparative Example 6, the friction coefficient fluctuation increased by 227.8%, and the wear rate of the carbon ceramic disc increased by 208.5%. This may be because the expanded graphite expands at high temperatures to form a sealing lubricating layer, filling the pores on the surface of the carbon ceramic disc; when only flake graphite is used, the high-temperature lubrication is insufficient, leading to increased friction coefficient fluctuation and accelerated wear of the carbon ceramic disc.

[0186] In Comparative Example 7, the average coefficient of friction decreased by 19.6%, while the brake pad wear rate increased by 104%. This may be because the needle-like structure of potassium titanate whiskers enhances the shear resistance of the friction surface and improves the coefficient of friction through the action of micro-protrusions; the absence of potassium titanate whiskers reduces the material's resistance to deformation, lowers the coefficient of friction, and accelerates wear.

[0187] In Comparative Example 8, the thermal degradation rate decreased by 15.2%, and the average friction coefficient decreased by 17.4%. This may be because antimony sulfide can stabilize the friction coefficient at high temperatures. When the amount of antimony sulfide is severely insufficient, the friction coefficient decreases significantly above 500°C, leading to a decrease in the thermal degradation rate.

[0188] In Comparative Example 9, the brake pad wear rate increased by 80%, and the friction coefficient fluctuation value increased by 172.2%. This may be because segmented pressurization gradually reduces the internal porosity of the material through densification, while direct pressurization leads to uneven density, localized stress concentration during friction, accelerated wear, and decreased frictional stability.

[0189] In Comparative Example 10, the wear rate of the carbon ceramic disc increased by 274.6%, while the thermal decay rate decreased by 19.6%. This may be because insufficient curing temperature led to incomplete cross-linking of the multiphase gradient binder, which easily released unreacted components at high temperatures, contaminating the surface of the carbon ceramic disc and exacerbating wear. At the same time, insufficient structural strength led to accelerated thermal decay.

[0190] In Comparative Example 11, the coefficient of friction decreased by 15.2%, while the wear rate of the carbon ceramic disc increased by 150.8%. This may be because the lack of lubrication from the silicon nitride coating increased the direct friction between the ceramic fibers and the carbon ceramic disc, reducing friction efficiency and scratching the surface of the carbon ceramic disc.

[0191] In Comparative Example 12, the friction coefficient fluctuation increased by 138.9%, and the noise occurrence rate increased by 400%. This may be because stepwise mixing ensures that the fibers are evenly dispersed to form a three-dimensional network, while single mixing can easily lead to fiber agglomeration, resulting in uneven contact on the friction surface and increased vibration and noise.

[0192] In summary, this solution, through the synergistic effect of three core innovative components and optimized preparation process, achieves a significant effect of increasing the coefficient of friction by 53.3% (Example 3 compared to Comparative Example 3) and reducing the wear rate of carbon ceramic discs by 78.4%. At the same time, it solves the problems of thermal degradation and noise in traditional formulations. Under the premise that the cost is only 1 / 5 of that of dedicated carbon ceramic brake pads, it achieves a level close to that of dedicated carbon ceramic brake pads.

[0193] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A brake pad adapted to carbon ceramic brake discs, characterized in that, The brake pads are composed of the following components by weight percentage: 14-26% nano-silicon nitride modified ceramic fiber, 5-15% carbon fiber, 6-16% aramid fiber, 22-49% lubricant, 7-17% binder, 7.2-28.1% friction modifier, and 3-23% filler. The preparation method of nano-silicon nitride modified ceramic fibers is as follows: a1. Add KH-560 to an ethanol-water solution with a volume ratio of 3:1 to prepare a 5% concentration KH-560 ethanol-water solution; a2. Place the aluminum silicate fiber in KH-560 ethanol-water solution and stir in a constant temperature water bath at 65-70℃ for 2-2.5h. Then take out the fiber and dry it in an oven at 120-130℃ for 2h to obtain activated fiber. a3. Weigh the activated fiber and nano silicon nitride at a mass ratio of 8:2, put them into a high-speed mixer, and stir at a speed of 3500-4000r / min for 30-40min to make the nano silicon nitride uniformly coat the fiber surface. a4. Place the mixed fibers in a nitrogen-protected furnace and calcine at 850℃ for 2.5 hours. After cooling, pulverize to 3-7 mm to obtain nano-silicon nitride modified ceramic fibers.

2. The brake pads adapted for carbon ceramic brake discs according to claim 1, characterized in that, The length of the aluminum silicate fiber is 5-10 mm, and the particle size of the nano silicon nitride is 20-50 nm.

3. The brake pads adapted for carbon ceramic brake discs according to claim 1, characterized in that, The lubricant's composition, by weight percentage of total components, is as follows: 8-18% graphene composite lubricating particles, 13-23% composite graphite, and 1-8% antimony sulfide; The preparation method of graphene composite lubricating particles is as follows: b1. Weigh natural graphite, graphene, and molybdenum disulfide in a mass ratio of 6:1:3, put them into a ball mill, and ball mill them at a speed of 250 r / min for 1.5 h. Then add a modified phenolic resin solution accounting for 12% of the total solid mass and stir until a uniform paste is formed. b2. Spray granulation of the obtained paste, with the inlet temperature set to 200℃ and the outlet temperature set to 90℃, to obtain particles with a particle size of 60-120μm. Then, place the particles in a nitrogen atmosphere and cure at 210-220℃ for 2-2.5h to obtain graphene composite lubricating particles.

4. The brake pads adapted for carbon ceramic brake discs according to claim 3, characterized in that, The particle size of natural graphite is 5-10 μm; graphene is a single layer with a particle size of 0.5-2 μm; molybdenum disulfide has a particle size of 1-3 μm; the modified phenolic resin is a modified phenolic resin with active groups of rubber, cashew nut shell oil and epoxy resin introduced, and the modified phenolic resin is dissolved in a 50% ethanol solution to form a modified phenolic resin solution.

5. The brake pads adapted to carbon ceramic brake discs according to claim 4, characterized in that, The composite graphite is made by uniformly mixing flake graphite and expanded graphite at a mass ratio of 2:1, wherein the particle size of flake graphite is 5-20μm and the particle size of expanded graphite is 10-50μm.

6. The brake pads adapted for carbon ceramic brake discs according to claim 5, characterized in that, The adhesive is a multiphase gradient adhesive, and its preparation method is as follows: c1. Weigh cashew nut shell oil modified phenolic resin, polyether ether ketone, and nitrile rubber powder according to a mass ratio of 6:3:1, add them to a twin-screw extruder, set the temperature of zone 1 to 130℃, zone 2 to 160℃, zone 3 to 190℃, and the screw speed to 250r / min, and carry out melt blending. c2. The extrudate obtained in c1 is cut into 3-5 mm particles by a pelletizer, dried in a vacuum drying oven at 78-80℃ for 4.5-5 h, and then frozen in an environment at -30℃ for 3 h. After that, it is taken out and placed at room temperature to complete the temperature shock modification, thus obtaining a multiphase gradient binder.

7. The brake pads adapted for carbon ceramic brake discs according to claim 6, characterized in that, The friction modifier is composed of the following components by weight percentage: 3-13% potassium titanate whiskers, 4-14% cashew nut shell oil friction powder, and 0.2-1.1% ultrafine tin powder, with a particle size of 3-5 μm. The filler consists of the following components: 2-12% barite powder and 1-11% barium sulfate.

8. A manufacturing process for brake pads adapted to carbon ceramic brake discs according to claim 7, characterized in that, The preparation process includes the following steps: S1. Take nano-silicon nitride modified ceramic fiber, carbon fiber and aramid fiber according to the proportion, dry them in an oven at 80℃ for 3 hours, cool them to room temperature and then add them to a high-speed mixer. Stir at 1100-1200r / min for 12-15 minutes to make the fibers disperse evenly. S2. Add the pre-softened multiphase gradient binder to the mixed fibers, adjust the speed to 1450-1500 r / min, and stir for 18-20 min. Then, add graphene composite lubricating particles, composite graphite, potassium titanate whiskers, cashew shell oil friction powder, antimony sulfide, barite powder, barium sulfate, and ultrafine tin powder in sequence, and stir at 1700-1800 r / min for 25-30 min. Stop the machine every 5 min to clean the mixing tank wall to ensure uniform mixing. S3. Preheat the brake pad preparation mold to 80℃, load the mixed material from S2 into the mold, apply a pressure of 7.5-8MPa for 3-4 minutes, then increase the pressure to 20-22MPa and hold the pressure for 10-12 minutes. S4. Perform a stepped solidification process on the material inside the mold in S3: Phase 1: Keep warm at 125-130℃ for 1.5-2 hours; Phase Two: Raise the temperature to 175-180℃ and hold for 2-2.5 hours; Phase 3: Raise the temperature to 215-220℃ and hold for 2-2.5 hours; It was then cooled to room temperature at a rate of 5°C / min. S5. Grind the surface of the cured brake pads to achieve a surface roughness Ra of 1.6-3.2μm. Finally, place them in an oven at 200℃ for secondary curing for 3.5-4 hours to remove residual volatiles, thus obtaining brake pads suitable for carbon ceramic brake discs.

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