Brake pad matched with carbon ceramic brake disc

Abstract

The invention belongs to the technical field of friction materials, and particularly relates to a brake pad matched with a carbon-ceramic brake disc. The preparation method of the brake pad comprises the following steps: preparing an impregnation liquid A from raw materials of methyl organic silicon resin, oxide ceramic and carbide ceramic, preparing an impregnation liquid B from raw materials of phenolic resin, epoxy resin, basalt microfibers, mullite and vermiculite, impregnating carbon sponge with the impregnation liquid A, curing and sintering to obtain a modified carbon skeleton, and preparing the modified carbon skeleton into the brake pad. And the impregnation liquid B is added into the modified carbon skeleton, the brake pad is obtained through vacuum pressurization impregnation, hot press molding, heat treatment, grinding and spraying, and the prepared brake pad has good friction performance and noise reduction and vibration reduction performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of friction materials, and particularly relates to a brake pad matching a carbon-ceramic brake disc. Background Art

[0002] Today, as cars become more and more popular, the requirements for the development of the automotive industry in China are also increasing day by day. With the continuous acceleration of the development speed of the automotive industry, the safety issues of the automotive industry are also issues that people attach great importance to. In the safety system of a car, the automotive braking system plays a very crucial role. And the brake friction material plays a very important role in the automotive braking system, and its performance is directly related to the safety, comfort and stability of driving a car, etc. Among them, the automotive brake pad is a consumable part in automotive components. The friction material of the automotive brake pad directly acts on the friction pair during braking of the car. Therefore, as the core safety component in the automotive braking system, it plays a decisive role in the safety performance of the car. The friction material mainly consists of three parts: matrix, reinforcement and filler. The matrix acts as a binder in the friction material, mainly organic phenolic resin; the reinforcement is the main framework material of the friction material, which plays a role in improving the mechanical properties and friction properties of the friction material, mainly organic-inorganic hybrid fibers; the filler is used as a friction property regulator to improve the overall performance of the friction material, mainly organic and inorganic particles, etc.

[0003] Chinese Patent with Publication No. CN101550976B discloses an environment-friendly ceramic brake pad and its manufacturing process. Its friction material is prepared from phenolic resin, nitrile rubber powder, ceramic fiber, mineral fiber, Kevlar fiber, potassium hexatitanate whisker, artificial graphite, zinc sulfide, copper powder, white vermiculite, and composite silicate whisker. The ceramic fiber and mineral fiber used have high biodegradability. The prepared brake pad has less dust fall, is non-toxic and harmless, has a stable friction coefficient, and a long service life. Chinese Patent with Publication No. CN109236903B discloses a double-layer micro-dust low-noise ceramic brake pad material and its preparation method. It adopts a double-layer friction structure, uses ceramic fiber, aramid fiber, and carbon fiber as reinforcing fibers, uses cashew oil-modified phenolic resin and nitrile rubber as binders, uses MoS 2 and micron-sized SiO 2 hollow spheres as friction coefficient regulators, uses Mo-B-Si-O composite crystals as friction noise reduction agents, and is prepared by supplementing fillers such as vermiculite, mica, barite, and alumina. The double-layer micro-dust low-noise ceramic brake pad material provided has a remarkable noise reduction effect, a low wear rate, good wear resistance, less dust generated, and a relatively extended service life.

[0004] Currently, the addition of the friction material reinforcement is mainly based on carbon fiber. However, the fibers do not contact each other in the matrix. When subjected to external forces, the cracks will spread rapidly, thus affecting the use. Summary of the Invention

[0005] One of the problems solved by the present invention is how to provide a brake pad with excellent high-temperature resistance and wear resistance.

[0006] To solve at least one of the above problems, the present invention provides a brake pad matching a carbon-ceramic brake disc. The preparation method of the brake pad includes: S100: Prepare impregnating solution A from raw materials including methyl silicone resin, oxide ceramic, and carbide ceramic. S200: Prepare impregnating solution B from raw materials including phenolic resin, epoxy resin, basalt microfiber, mullite, and vermiculite. S300: Impregnate carbon sponge with impregnating solution A, and obtain a modified carbon skeleton through curing and sintering. S400: Add impregnating solution B to the modified carbon skeleton, and obtain the brake pad through vacuum pressure impregnation, hot pressing, heat treatment, grinding, and spraying.

[0007] In any of the above technical solutions, in step S100, the methyl silicone resin is polydimethylsiloxane, the oxide ceramic is modified alumina, and the carbide ceramic is modified silicon carbide.

[0008] In any of the above technical solutions, step S100 specifically includes: adding polydimethylsiloxane to a n-hexane solution, mixing evenly, then adding modified alumina and modified silicon carbide thereto, and ultrasonically stirring for 20 - 40 min to obtain impregnating solution A.

[0009] In any of the above technical solutions, the preparation process of the phenolic resin in step S200 is: adding phenol to a reactor, raising the temperature to 45°C, adding formaldehyde after the phenol melts into a liquid, mixing evenly, then adding sodium hydroxide, and raising the temperature to 85 - 95°C and stirring for 3 - 6 h to obtain a brownish-red viscous phenolic resin liquid for standby.

[0010] In any of the above technical solutions, step S200 specifically includes: S210: Add phenolic resin and epoxy resin to a reactor, stir for 20 - 40 min, then add modified basalt microfiber, mullite, and vermiculite, and continue to stir for 20 - 40 min to obtain a mixture. S220: Place the mixture in a vacuum drying oven for semi-gel treatment, and after the treatment is completed, add a curing agent and an accelerator, and mix evenly to obtain the impregnating solution B.

[0011] In any of the above technical solutions, the preparation method of the modified basalt microfiber is: A1. Add absolute ethanol to deionized water. After mixing evenly, add a silane coupling agent and stir for 4 - 10 min to obtain a hydrolyzed solution of the silane coupling agent. A2. Add HP302 emulsion to deionized water. After ultrasonic dispersion for 10 - 20 min, add the hydrolyzed solution of the silane coupling agent, stir for 5 - 15 min, then add basalt fibers, stir for 40 - 60 min, filter, let it stand at room temperature for 24 - 36 h, and then put it into a vacuum drying oven and dry at 105 - 125 °C for 2 - 4 h to obtain dried basalt fibers. A3. Put the dried basalt fibers into a crusher and crush them for 8 - 10 s to obtain modified basalt microfibers.

[0012] In any of the above technical solutions, step S300 specifically includes: Immerse the carbon sponge in immersion liquid A, heat it in a vacuum drying oven to 45 - 60 °C for 2 - 4 h, then raise the temperature to 100 - 120 °C and heat for 4 - 6 h, and finally sinter it at 1200 - 1400 °C in a vacuum environment for 1 - 2 h to obtain a modified carbon skeleton.

[0013] In any of the above technical solutions, the preparation process of the carbon sponge is as follows: Disperse graphene oxide in deionized water, add ethylenediamine, mix evenly, then add ammonia water to adjust the pH of the solution to weak alkaline, transfer the solution to a sealed container, raise the temperature to 90 - 100 °C and heat for 10 - 15 h, then naturally cool to room temperature to obtain a graphene oxide hydrogel. Perform multiple dialysis with a water - alcohol solution, take it out after freezing at - 30 °C for 10 - 14 h, and freeze - dry for 48 - 56 h to obtain the carbon sponge.

[0014] In any of the above technical solutions, step S400 specifically includes: Immerse the obtained modified carbon skeleton in immersion liquid B, put them together into an impregnation tooling, perform vacuum pressure impregnation in an impregnation furnace to obtain a preform, place the preform on a hot - press molding machine for hot - pressing to obtain a sample blank, and then perform heat treatment on the sample blank, and obtain the brake pad after grinding and spraying.

[0015] The present invention also provides a brake pad that matches a carbon - ceramic brake disc, and this brake pad is obtained by using the preparation method of any of the above technical solutions. Beneficial effects

[0016] The present invention provides a preparation method of a brake pad matching a carbon-ceramic brake disc. First, alumina and silicon carbide are dispersed in polydimethylsiloxane to obtain an impregnating solution A for filling a carbon sponge. After curing and sintering, a carbon sponge skeleton covered with oxide ceramics and carbide ceramics is obtained. Further, a blend of epoxy resin and phenolic resin is used as the matrix, and modified basalt fiber, mullite, and vermiculite are added as fillers to obtain an impregnating solution B for filling the modified carbon sponge skeleton. After post-treatments such as impregnation and hot pressing, a brake pad is obtained. The use of a blend of epoxy resin and phenolic resin can utilize the respective advantages for complementarity. At the same time, the epoxy resin has good wettability to the ceramic skeleton, enabling the impregnating solution B to better fill the modified carbon sponge skeleton. In addition, compared with the carbon fiber filled in the prior art, using a carbon sponge as the carbon skeleton has a continuous network structure, can exist in a continuous form in the matrix, and avoids the rapid propagation of cracks when subjected to external forces. This network structure can interact and restrict with the resin matrix, so that the prepared brake pad has good friction performance. Detailed Embodiments

[0017] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of specific embodiments of the present invention is provided.

[0018] The polydimethylsiloxane (analytical pure) used in the present invention is purchased from Dow Corning Corporation, USA. Alumina (α-Al 2 O 3 , average particle size 100 nm), silicon carbide (<100 nm particle size), vermiculite (20 - 40 mesh), curing agent METHPA (methyltetrahydrophthalic anhydride), accelerator DMP-30 (N,N-dimethylformamide), graphene oxide (number of layers: 15 - 20, oxidation 4 - 10%, G476611) are purchased from Shanghai Aladdin Technology. Phenol (AR) and formaldehyde (AR) are purchased from Sinopharm Chemical Reagent Co., Ltd. E51 type phenolic resin (epoxy value 0.48 - 0.54 eq / 100 g) is purchased from Shanghai Xiongrun Resin Co., Ltd. HP302 emulsion is purchased from McMenn Co., Ltd. Basalt fiber (diameter of basalt fiber is 12.5 μm, length is 200 - 1000 μm, aspect ratio is 10 - 100) is purchased from Jiangsu Green Valley New Materials Technology Development Co., Ltd. Mullite (200 mesh) is purchased from Zhengzhou Yifan Refractory Materials Co., Ltd.

[0019] Unless otherwise specified, the reagents and raw materials used in the present invention can be purchased through commercial channels. The experimental methods without specific conditions noted in the following examples are carried out according to conventional methods and conditions, or selected according to the product instructions.

[0020] The brake pad is a key component in the automotive braking system, responsible for converting the kinetic energy of the vehicle into heat energy through friction with the brake disc or brake drum, thereby achieving deceleration or stopping.

[0021] The present invention provides a brake pad that matches a carbon-ceramic brake disc, which is characterized by good high-temperature resistance and wear resistance. The preparation method of the brake pad of the present invention includes: S100: Prepare an impregnating solution A from raw materials including methyl silicone resin, oxide ceramics, and carbide ceramics; S200: Prepare an impregnating solution B from raw materials including phenolic resin, epoxy resin, basalt microfiber, mullite, and vermiculite; S300: Impregnate carbon sponge with the impregnating solution A, and obtain a modified carbon skeleton through curing and sintering; S400: Add the impregnating solution B to the modified carbon skeleton, and obtain the brake pad through vacuum pressure impregnation, hot pressing, heat treatment, grinding, and spraying.

[0022] In the above steps, the oxide ceramics have good thermal stability and chemical stability, can maintain their physical properties without undergoing chemical reactions in a high-temperature environment, can ensure that the brake pad works effectively during high-temperature braking, and their good wear resistance and low density can reduce the wear of the brake pad and extend its service life. The low density also helps to reduce the overall weight of the vehicle, thereby improving fuel efficiency. The carbide ceramics can provide excellent hardness and wear resistance, can provide good braking performance under extreme conditions, and their high thermal conductivity enables the brake pad to dissipate heat quickly during braking, thereby reducing the phenomenon of thermal fade, improving braking consistency, and their low density and high strength can meet the preparation requirements of lightweight and high-performance brake pads.

[0023] The methyl silicone resin is mainly composed of silicon-oxygen bonds and has excellent thermal stability. It can strengthen the bonding of components such as fibers, fillers, and regulators into a whole, playing a role in transmitting and balancing loads. Compared with directly mixing various raw materials in the prior art, in the present invention, the oxide ceramics and carbide ceramics are dispersed in the methyl silicone resin, and further filled into the carbon sponge. Through curing and sintering, the oxide ceramics and carbide ceramics can be evenly covered on the carbon sponge skeleton, thereby realizing the modification of the carbon skeleton by ceramic particles, enhancing the high-temperature resistance and wear resistance of the carbon skeleton, and at the same time achieving a tight connection between the ceramic particles and the carbon skeleton.

[0024] Phenolic resin is a high molecular organic polymer prepared by the condensation reaction of phenol and formaldehyde under certain conditions. It has good heat resistance, high bonding strength and excellent mechanical properties, and is widely used in the preparation of brake pads. During the preparation process, phenolic resin softens at high temperature and presents a viscous flow state, which can be evenly distributed in the entire preparation material system, enabling other raw materials in the material to maintain the structural integrity under thermal stress and mechanical action. However, it has low toughness and high brittleness. As one of the raw materials for preparing brake pads, epoxy resin can react with curing agents to form three-dimensional cured products. It has a low curing shrinkage rate and a controllable crosslinking degree, and can have good wettability with ceramic skeletons. However, it has poor heat resistance and poor crack resistance. Therefore, in the present invention, epoxy resin and phenolic resin are mixed to utilize their respective advantages for complementarity to improve their comprehensive performance. By blending phenolic resin and epoxy resin and adding other fillers to fill the modified carbon skeleton, vacuum pressure impregnation can overcome the large surface tension of the polymer and infiltrate into each position through capillary channels to prevent incomplete filling.

[0025] In the technical solution of the present invention, in step S100, the methyl silicone resin is polydimethylsiloxane, the oxide ceramic is modified alumina, and the carbide ceramic is modified silicon carbide.

[0026] In the technical solution of the present invention, step S100 specifically includes: adding polydimethylsiloxane to a n-hexane solution, and after mixing evenly, adding modified alumina and modified silicon carbide thereto, and ultrasonically stirring for 20 - 40 min to obtain impregnation liquid A.

[0027] In the technical solution of the present invention, in step S100, by mass ratio, n-hexane : polydimethylsiloxane : modified alumina : modified silicon carbide = 100 : (3.5 - 7.5) : (4 - 10) : (6 - 15).

[0028] In the technical solution of the present invention, the preparation method of the modified alumina is as follows: B1. Add alumina and absolute ethanol to a reactor, and ultrasonically stir for 20 - 40 min to obtain a suspension containing alumina; wherein, by mass ratio, alumina : absolute ethanol = (15 - 30) : (180 - 300); B2. Add a silane coupling agent to deionized water, and adjust the pH value of the mixture to 3 - 4 by adding glacial acetic acid. Then mix the mixture with the alumina-containing suspension obtained in step B1, raise the temperature to 70 - 80 °C and stir for 3 - 6 h. After filtration, washing, and drying, alumina modified with a silane coupling agent is obtained. Among them, by mass ratio, deionized water : silane coupling agent : alumina-containing suspension = 10 : (1.8 - 2.2) : (180 - 220). Wash with deionized water. After filtration and washing 3 - 5 times, place it in a vacuum oven at 70 - 90 °C and dry for 12 - 18 h.

[0029] In the technical solution of the present invention, the preparation method of modified silicon carbide is as follows: C1. Add silicon carbide and absolute ethanol to a reactor, and ultrasonically stir for 20 - 40 min to obtain a silicon carbide-containing suspension. Among them, by mass ratio, silicon carbide : absolute ethanol = (12 - 25) : (180 - 300); C2. Add a silane coupling agent to deionized water, and adjust the pH value of the mixture to 3 - 4 by adding glacial acetic acid. Then mix the mixture with the silicon carbide-containing suspension obtained in step C1, raise the temperature to 70 - 80 °C and stir for 3 - 6 h. After filtration, washing, and drying, silicon carbide modified with a silane coupling agent is obtained. Among them, by mass ratio, deionized water : silane coupling agent : silicon carbide-containing suspension = 10 : (1.8 - 2.2) : (150 - 210). Wash with deionized water. After filtration and washing 3 - 5 times, place it in a vacuum oven at 70 - 90 °C and dry for 12 - 18 h.

[0030] In this step, in order to improve the dispersibility of alumina and silicon carbide in polydimethylsiloxane, alumina and silicon carbide are modified with a silane coupling agent. The silane coupling agent contains both a silicon alkyl group that can react with inorganic materials and an organic functional group that can react with organic polymers in its molecular structure. When the silane coupling agent acts on alumina or silicon carbide, it can bond the inorganic material (alumina or silicon carbide) and the organic resin (polydimethylsiloxane) through a chemical reaction, form an organic molecular layer on the surface of the inorganic material, and at the same time enhance the interfacial compatibility with the organic matrix.

[0031] In the technical solution of the present invention, the preparation process of phenolic resin in step S200 is as follows: Add phenol to a reactor, raise the temperature to 45 °C. After the phenol melts into a liquid, add formaldehyde, mix evenly, then add a 20% sodium hydroxide solution, raise the temperature to 85 - 95 °C and stir for 3 - 6 h to obtain a brownish-red viscous phenolic resin liquid for standby. Among them, by mass ratio, phenol : formaldehyde : 20% sodium hydroxide solution = (47 - 56.5) : (18 - 22.5) : 10.

[0032] In the technical solution of the present invention, step S200 specifically includes: S210. Add phenolic resin and epoxy resin into the reactor, stir for 20 - 40 min, then add modified basalt microfiber, mullite and vermiculite, and continue to stir for 20 - 40 min to obtain a mixed solution; wherein, by mass ratio, phenolic resin: epoxy resin: modified basalt microfiber: mullite: vermiculite = (45 - 55): (30 - 40): (10 - 15): (8 - 12): (6 - 10); wherein, the epoxy resin is E51 type epoxy resin; S220. Place the mixed solution in a vacuum drying oven for semi - gel treatment. After the treatment is completed, add a curing agent and an accelerator, and mix evenly to obtain the impregnating solution B; wherein, by mass ratio, mixed solution: curing agent: accelerator = 100: (18 - 25): (0.35 - 0.65). The semi - gel treatment process is: place it in a vacuum oven at 80 - 90 °C and dry for 100 - 120 min for dehydration and degassing treatment.

[0033] In the technical solution of the present invention, the preparation method of the modified basalt microfiber is as follows: A1. Add anhydrous ethanol into deionized water, mix evenly, then add a silane coupling agent, and stir for 4 - 10 min to obtain a silane coupling agent hydrolysis solution; wherein, by mass ratio, deionized water: anhydrous ethanol: silane coupling agent = (2 - 5): (40 - 50): 1; A2. Add HP302 emulsion into deionized water, ultrasonically disperse for 10 - 20 min, then add the silane coupling agent hydrolysis solution, stir for 5 - 15 min, then add basalt fiber, stir for 40 - 60 min, then filter, let it stand at room temperature for 24 - 36 h, and then put it into a vacuum drying oven and dry at 105 - 125 °C for 2 - 4 h to obtain dried basalt fiber; wherein, by mass ratio, deionized water: HP302 emulsion: silane coupling agent hydrolysis solution: basalt fiber = (40 - 50): 1: (45 - 55): (18 - 22); A3. Put the dried basalt fiber into a pulverizer and pulverize it for 8 - 10 s to obtain the modified basalt microfiber.

[0034] In this step, basalt fiber is an inorganic environmental - friendly high - performance material formed by high - temperature and high - speed drawing of basalt. It is composed of various compounds, including SiO 2 , MgO, Al 2 O 3 etc., where SiO 2It exists in the form of a tetrahedron, and each tetrahedron is connected by a common vertex to form a reticular skeleton structure. Al atoms can replace Si or exist in the tetrahedral interstitial space to form a secondary skeleton, and other metal atoms are located on the side of the tetrahedron. The structural characteristics of basalt fiber itself determine that it has excellent high-temperature resistance, excellent mechanical properties, good chemical stability and good sound absorption performance. However, since the surface of basalt fiber is inorganic-philic, while the resin is an organic substance, there is an interfacial compatibility problem between the two. Therefore, a silane coupling agent and HP302 emulsion are used to modify it. Compared with the prior art in which only a silane coupling agent is used to modify it, since the surface of basalt fiber contains not only Si but also atoms such as Mg, Al, Ca, K other than Si, the surface of basalt fiber cannot be completely covered by silane coupling agent molecules, which will reduce the interfacial compatibility when basalt fiber binds to the resin. Depositing an emulsion with a composition similar to that of the resin matrix on the surface of basalt fiber not connected with the coupling agent will effectively improve the interfacial compatibility between basalt fiber and the resin. Therefore, modifying basalt fiber with a coupling agent and an emulsion simultaneously can make basalt fiber and the resin have good interfacial bonding.

[0035] When braking, a large amount of heat will be generated due to friction between the brake pads, resulting in a sharp rise in temperature. Mullite is a high-temperature resistant material that can maintain stable physical and chemical properties in a high-temperature environment. Therefore, mullite is added during the preparation of the present invention. At high temperatures, the strength and hardness of mullite gradually increase, and it has good high-temperature creep performance and thermal shock resistance, and will not become soft or deformed due to high temperature, ensuring the reliability of the braking effect. In addition, the high hardness of mullite gives it excellent wear resistance. The presence of mullite can effectively improve the wear resistance of the brake pads, reduce the wear rate of the brake pads during use, reduce the replacement frequency, save costs and improve the use safety of the vehicle at the same time.

[0036] During the use of the vehicle, in order to improve the comfort of use and avoid noise pollution, the braking noise needs to be controlled within a reasonable range. When adding high-hardness fillers, it will generate relatively large braking noise. Therefore, in order to reduce the braking noise, vermiculite with sound-absorbing properties is also added during the preparation process. Vermiculite belongs to a secondary metamorphic mineral of hydrous aluminum salt, its composition contains magnesium, its structure is a hollow layered structure, with a small density and a loose texture, and it can effectively absorb noise and reduce the sound pollution caused by braking.

[0037] In the technical solution of the present invention, step S300 specifically includes: immersing the carbon sponge in the impregnation liquid A, heating it to 45-60°C in a vacuum drying oven for 2-4 hours, then heating it to 100-120°C for 4-6 hours, and finally sintering it at 1200-1400°C in a vacuum environment for 1-2 hours to obtain a modified carbon skeleton; wherein, in terms of mass ratio, carbon sponge: impregnation liquid A=0.01:(12-14), ensuring that the carbon sponge is completely immersed in the impregnation liquid A.

[0038] In this step, the carbon sponge is immersed in the impregnation liquid A and placed in a vacuum environment, so that the impregnation liquid A can be quickly filled into the pores of the carbon sponge, which is conducive to full filling. The polydimethylsiloxane is first pre-cured by heating to 45-60° C. in a vacuum drying oven, and then the temperature is increased to further cure, and finally sintered at a high temperature to obtain a carbon skeleton modified with aluminum oxide and silicon carbide.

[0039] In the technical scheme of the present invention, the preparation process of the carbon sponge is as follows: graphene oxide is dispersed in deionized water, ethylenediamine is added, and after mixing evenly, ammonia water is added to adjust the pH value of the solution to 8-9, the solution is transferred to a sealed container, the temperature is increased to 90-100°C, heated for 10-15 hours, and then naturally cooled to room temperature to obtain a graphene oxide hydrogel, and dialyzed multiple times using a hydroalcohol solution, and the mixture is taken out after being frozen at -30°C for 10-14 hours, and freeze-dried for 48-56 hours to obtain a carbon sponge; wherein, in terms of mass ratio, graphene oxide: deionized water: ethylenediamine = 0.01: (2.2-2.8): (0.008-0.011).

[0040] In this step, carbon sponge is prepared using graphene oxide as raw material by using a pressurized hydrothermal method. In the preparation of prior art brake pads, carbon fibers are often added as reinforcements, but when the fibers are unevenly dispersed in the matrix, the carbon fibers will fall off and be pulled out during friction. Since the fibers are not in contact with each other, when the external force is greater than the resistance, the cracks will rapidly expand. Therefore, in the present invention, carbon sponge is used as the carbon skeleton. This network structure exists in a continuous form in the matrix phase and does not destroy the topological continuous phase of the matrix phase, so that the network structure and the resin matrix are mutually restricted, while maintaining their own excellent performance, they complement each other, thereby improving the comprehensive performance of the prepared product.

[0041] In the technical solution of the present invention, step S400 specifically includes: immersing the obtained modified carbon skeleton into an impregnation liquid B, placing them together in an impregnation tooling, performing vacuum pressure impregnation in an impregnation furnace to obtain a preform, placing the preform on a hot pressing molding machine for hot pressing to obtain a sample, and then heat treating the sample, and obtaining the brake pad after grinding and spraying; wherein, in terms of mass ratio, modified carbon skeleton: impregnation liquid B=0.01:(15-18).

[0042] In this step, the impregnation pressure of vacuum pressure impregnation is 2 - 4 MPa, and the time is 4 - 6 h; the hot pressing conditions are that the pressing force is 16 - 22 MPa, the pressing temperature is 150 - 180 °C, and the hot pressing time is 6 - 10 min; the heat treatment conditions are that the heat treatment temperature is 140 - 190 °C, the heat preservation time is 7 - 12 h, and finally it is cooled to room temperature; the grinding process is as follows: the sample blank after heat treatment is trimmed, deburred and ground flat by a disk grinder, and the grinding speed is controlled at 25 - 45 r / min; the spraying process is an electrostatic spraying process, and the rotation speed of the electrostatic spraying process equipment is 350 - 400 r / min, and the temperature is 160 - 170 °C.

[0043] The present invention also provides a brake pad matching a carbon-ceramic brake disc, and the brake pad is obtained by using the preparation method of any of the above technical solutions. Example 1

[0044] This example provides a preparation method of a brake pad matching a carbon-ceramic brake disc, which includes the following steps: S1. According to the mass ratio of n-hexane: polydimethylsiloxane: modified alumina: modified silicon carbide = 100: 4.5: 5: 8, polydimethylsiloxane is added to the n-hexane solution. After mixing evenly, modified alumina and modified silicon carbide are added thereto, and ultrasonic stirring is carried out for 30 min to obtain impregnating liquid A; S2. According to the mass ratio of phenolic resin: E51 type epoxy resin: modified basalt microfiber: mullite: vermiculite = 50: 35: 12: 10: 8, phenolic resin and E51 type epoxy resin are added to the reactor. After stirring for 30 min, modified basalt microfiber, mullite and vermiculite are added, and stirring is continued for 30 min to obtain a mixed liquid; S3. According to the mass ratio of the mixture: curing agent METHPA: accelerator DMP-30 = 100: 22: 0.45, the mixed liquid is placed in a vacuum oven at 85 °C and dried for 120 min for semi-gel treatment of dehydration and degassing. After the treatment is completed, the curing agent METHPA and the accelerator DMP-30 are added and mixed evenly to obtain impregnating liquid B; S4. According to the mass ratio of carbon sponge: impregnating liquid A = 0.01: 13, the carbon sponge is completely immersed in the impregnating liquid A, heated to 50 °C in a vacuum drying oven for 3 h, then the temperature is raised to 110 °C and heated for 5 h, and finally sintered at 1300 °C in a vacuum environment for 1.5 h to obtain a modified carbon skeleton; S5. According to the mass ratio of the modified carbon skeleton to the impregnating solution B of 0.01:16, completely immerse the obtained modified carbon skeleton in the impregnating solution B, place them together in the impregnating tooling, and perform vacuum pressure impregnation in the impregnating furnace to obtain a preform. Place the preform on a hot press to perform hot pressing to obtain a sample blank, and then perform heat treatment on the sample blank. After grinding and spraying, a brake pad is obtained. Among them, the impregnation pressure for vacuum pressure impregnation is 3 MPa, and the time is 5 h; the hot pressing conditions are a pressing force of 20 MPa, a pressing temperature of 160 °C, and a hot pressing time of 8 min; the heat treatment conditions are a heat treatment temperature of 160 °C, heat preservation for 10 h, and finally cooling to room temperature; the grinding process is as follows: use a disk grinder to perform trimming, deburring, and grinding on the sample blank after heat treatment, and control the grinding speed at 35 r / min; the spraying process uses an electrostatic spraying process, and the rotation speed of the electrostatic spraying process equipment is 380 r / min, and the temperature is 165 °C.

[0045] Among them, the preparation process of the phenolic resin is as follows: According to the mass ratio of phenol: formaldehyde: 20% sodium hydroxide solution of 52:21:10, add phenol to the reactor, raise the temperature to 45 °C, wait for the phenol to melt into a liquid, then add formaldehyde, mix evenly, add 20% sodium hydroxide solution, raise the temperature to 90 °C and stir for 4 h to obtain a brownish-red viscous phenolic resin liquid for standby.

[0046] The preparation method of the modified basalt microfiber is as follows: A1. According to the mass ratio of deionized water: absolute ethanol: silane coupling agent KH560 of 3:45:1, add absolute ethanol to deionized water, mix evenly, then add silane coupling agent KH560, and stir for 8 min to obtain a silane coupling agent hydrolysis solution; A2. According to the mass ratio of deionized water: HP302 emulsion: silane coupling agent hydrolysis solution: basalt fiber of 45:1:50:20, add HP302 emulsion to deionized water, perform ultrasonic dispersion for 15 min, then add the silane coupling agent hydrolysis solution, stir for 12 min, then add basalt fiber, stir for 45 min, filter, let it stand at room temperature for 28 h, and then put it into a vacuum drying oven and dry at 110 °C for 3 h to obtain dried basalt fiber; A3. Put the dried basalt fiber into a crusher and crush it for 9 s to obtain modified basalt microfiber.

[0047] The preparation method of the modified alumina is as follows: B1. According to the mass ratio of alumina: absolute ethanol of 25:220, add alumina and absolute ethanol to the reactor, perform ultrasonic stirring for 30 min to obtain a suspension containing alumina; B2. Add silane coupling agent KH560 into deionized water according to the mass ratio of deionized water : silane coupling agent KH560 : alumina-containing suspension = 10 : 2.1 : 200. Adjust the pH value of the mixture to 3 - 4 by adding glacial acetic acid. Then mix the mixture with the alumina-containing suspension obtained in step B1. Raise the temperature to 75 °C, stir for 4 h, then filter and wash with deionized water. Repeat the filtration-washing operation 5 times, and then place it in a vacuum oven at 80 °C to dry for 15 h to obtain alumina modified by silane coupling agent.

[0048] The preparation method of modified silicon carbide is as follows: C1. Add silicon carbide and absolute ethanol into the reactor according to the mass ratio of silicon carbide : absolute ethanol = 22 : 220. Ultrasonically stir for 30 min to obtain a silicon carbide-containing suspension. C2. Add silane coupling agent KH560 into deionized water according to the mass ratio of deionized water : silane coupling agent KH560 : silicon carbide-containing suspension = 10 : 2.1 : 200. Adjust the pH value of the mixture to 3 - 4 by adding glacial acetic acid. Then mix the mixture with the silicon carbide-containing suspension obtained in step C1. Raise the temperature to 75 °C, stir for 4 h, then filter and wash with deionized water. Repeat the filtration-washing operation 5 times, and then place it in a vacuum oven at 80 °C to dry for 15 h to obtain silicon carbide modified by silane coupling agent.

[0049] The preparation process of carbon sponge is as follows: Disperse graphene oxide in deionized water according to the mass ratio of graphene oxide : deionized water : ethylenediamine = 0.01 : 2.4 : 0.009. Add ethylenediamine, mix evenly, then add ammonia water to adjust the pH of the solution to 8 - 9. Transfer the solution to a sealed container, raise the temperature to 95 °C, heat for 12 h, and then naturally cool to room temperature to obtain graphene oxide hydrogel. Perform multiple dialysis with a water-alcohol solution, take it out after freezing at - 30 °C for 12 h, and obtain carbon sponge after freeze-drying for 52 h. Example 2

[0050] Compared with Example 1, this example has the following differences, and the rest refer to Example 1.

[0051] By mass ratio, in step S1, n-hexane: polydimethylsiloxane: modified alumina: modified silicon carbide = 100: 3.5: 4: 6; in step S2, phenolic resin: E51 type epoxy resin: modified basalt fiber: mullite: vermiculite = 45: 30: 10: 8: 6; in step S3, the mixed solution: curing agent METHPA: accelerator DMP-30 = 100: 18: 0.35. The mixed solution is placed in a vacuum oven at 80 °C and dried for 100 min for semi-gel treatment of dehydration and degassing; in step S4, carbon sponge: impregnating solution A = 0.01: 12. After immersion in impregnating solution A, it is heated to 45 °C in a vacuum drying oven for 2 h and then the temperature is raised to 100 °C and heated for 4 h, and finally sintered at 1200 °C for 1 h in a vacuum environment; in step S5, modified carbon skeleton: impregnating solution B = 0.01: 15. The impregnation pressure for vacuum pressure impregnation is 2 MPa and the time is 4 h; the hot pressing conditions are a pressing force of 16 MPa, a pressing temperature of 150 °C, and a hot pressing time of 6 min; the heat treatment conditions are a heat treatment temperature of 140 °C, heat preservation for 7 h, and finally cooling to room temperature; the grinding process is as follows: the sample blank after heat treatment is trimmed, deburred, and ground flat using a disk grinder, and the grinding speed is controlled at 25 r / min; the spraying process uses an electrostatic spraying process, and the rotation speed of the electrostatic spraying process equipment is 350 r / min and the temperature is 160 °C. Example Three

[0052] Compared with Example One, this example has the following differences, and the rest refer to Example One.

[0053] By mass ratio, in step S1, n-hexane: polydimethylsiloxane: modified alumina: modified silicon carbide = 100: 7.5: 10: 15; in step S2, phenolic resin: E51 epoxy resin: modified basalt fiber: mullite: vermiculite = 55: 40: 15: 12: 10; in step S3, the mixed solution: curing agent METHPA: accelerator DMP-30 = 100: 25: 0.65. The mixed solution is placed in a vacuum oven at 90 °C and dried for 120 min for semi-gel treatment of dehydration and degassing; in step S4, carbon sponge: impregnating solution A = 0.01: 14. After immersion in impregnating solution A, it is heated to 60 °C in a vacuum drying oven for 4 h, then the temperature is raised to 120 °C and heated for 6 h, and finally sintered at 1400 °C in a vacuum environment for 2 h; in step S5, modified carbon skeleton: impregnating solution B = 0.01: 18. The impregnation pressure for vacuum pressure impregnation is 4 MPa and the time is 6 h. The hot pressing conditions are a pressing force of 22 MPa, a pressing temperature of 180 °C, and a hot pressing time of 10 min. The heat treatment conditions are a heat treatment temperature of 190 °C, heat preservation for 12 h, and finally cooling to room temperature. The grinding process is as follows: The heat-treated sample blank is trimmed, deburred, and ground using a disk grinder, and the grinding speed is controlled at 45 r / min. The spraying process uses an electrostatic spraying process, and the rotation speed of the electrostatic spraying process equipment is 400 r / min and the temperature is 170 °C.

[0054] Comparative Example 1 Compared with Example 1, the raw materials and specific preparation process of this comparative example are basically the same as those of Example 1, except that in step S1, alumina and silicon carbide are not modified, specifically as follows: In step S1, according to the mass ratio of n-hexane: polydimethylsiloxane: alumina: silicon carbide = 100: 4.5: 5: 8, polydimethylsiloxane is added to the n-hexane solution. After mixing evenly, alumina and silicon carbide are added thereto, and ultrasonic stirring is carried out for 30 min to obtain impregnating solution A.

[0055] Comparative Example 2 Compared with Example 1, the raw materials and specific preparation process of this comparative example are basically the same as those of Example 1, except that in the preparation process of modified basalt microfibers, only silane coupling agent is used to modify basalt fibers, specifically as follows: The preparation method of the modified basalt microfibers is as follows: A1. According to the mass ratio of deionized water: absolute ethanol: silane coupling agent = 3: 45: 1, absolute ethanol is added to deionized water. After mixing evenly, silane coupling agent is added, and stirring is carried out for 8 min to obtain a silane coupling agent hydrolysis solution; A2. Add basalt fibers to the hydrolyzed solution of silane coupling agent at a mass ratio of silane coupling agent hydrolyzed solution: basalt fibers = 50:16. Adjust the pH value of the mixture to 3 - 4 by adding glacial acetic acid, then perform ultrasonic dispersion for 25 min and filter. Wash with deionized water, repeat the filtration - washing operation 5 times, and then place it in a vacuum drying oven and dry at 110 °C for 3 h to obtain dried basalt fibers; A3. Put the dried basalt fibers into a pulverizer and pulverize for 9 s to obtain modified basalt microfibers.

[0056] Comparative Example 3 Compared with Example 1, the raw materials and specific preparation process of this comparative example are basically the same as those of Example 1, except that in step S2, the basalt fibers are not modified, specifically as follows: In step S2, at a mass ratio of phenolic resin: E51 epoxy resin: basalt microfibers: mullite: vermiculite = 50:35:12:10:8, add phenolic resin and E51 epoxy resin to the reactor. After stirring for 30 min, add basalt microfibers, mullite, and vermiculite, and continue stirring for 30 min to obtain a mixture; The preparation method of the basalt microfibers is as follows: Place the basalt fibers in a vacuum drying oven and dry at 110 °C for 3 h to obtain dried basalt fibers. Put the dried basalt fibers into a pulverizer and pulverize for 9 s to obtain basalt microfibers.

[0057] Comparative Example 4 Compared with Example 1, the raw materials and specific preparation process of this comparative example are basically the same as those of Example 1, except that in the preparation process of step S2, epoxy resin is not added, specifically as follows: In step S2, at a mass ratio of phenolic resin: modified basalt fibers: mullite: vermiculite = 50:8:7:4, add phenolic resin to the reactor. After stirring for 30 min, add modified basalt microfibers, mullite, and vermiculite, and continue stirring for 30 min to obtain a mixture.

[0058] Comparative Example 5 Compared with Example 1, the raw materials and specific preparation process of this comparative example are basically the same as those of Example 1, except that in the preparation process of step S4, the carbon sponge is replaced by carbon fiber, specifically as follows: In step S4, at a mass ratio of carbon fiber: impregnating solution A = 0.01:13, completely immerse the carbon fiber in impregnating solution A. Raise the temperature to 50 °C in a vacuum drying oven and heat for 3 h, then raise the temperature to 110 °C and heat for 5 h. Finally, sinter at 1300 °C in a vacuum environment for 1.5 h to obtain a modified carbon fiber skeleton; In step S5, the obtained modified carbon fiber skeleton is completely immersed in immersion liquid B according to the mass ratio of modified carbon fiber skeleton: immersion liquid B = 0.01:16, and they are jointly placed in an impregnation tooling, and vacuum pressure impregnation is carried out in an impregnation furnace to obtain a preform. The preform is placed on a hot press to be hot pressed to obtain a sample blank, and then the sample blank is heat treated, and after grinding and spraying, a brake pad is obtained.

[0059] Related tests: The brake pads prepared in Examples 1 to 3 and Comparative Examples 1 to 5 are made into cuboid samples of 25 mm × 25 mm × 7 mm, and their performance is tested.

[0060] Hardness test: The test standard is GB / T3398.2-2008, and the hardness standard is Rockwell hardness HRL.

[0061] Noise test: The noise standard uses two major standards, GB3096-2008 and GB22337-2008, to test its equivalent sound pressure level; the environmental noise is detected at a measurement distance of 3.5 m and a height of 1.2 m from the ground. Each sample is tested 5 times, and the average value is taken; Friction performance test: Refer to QC / T 520-2019 for detection, and use an MM-1000 type friction testing machine to test its friction coefficient and wear amount at 350°C.

[0062] Thermal expansion rate: Refer to GB / T22310-2023 to test its thermal expansion rate at 400°C.

[0063] Compressive strain: Refer to GB / T 22311-2023 to test its compressive strain at 400°C.

[0064] The test results are shown in Table 1.

[0065] Table 1 Related performance test results

[0066] As can be seen from the above test results, the comprehensive performance of Examples 1 to 3 is better than that of Comparative Examples 1 to 5, and the performance of the brake pads prepared in Example 1 is the best. From the comparison of the test results of Example 1 and Comparative Example 2 (only using silane coupling agent to modify basalt fiber), it can be seen that the performance of only using silane coupling agent to modify basalt fiber is relatively poor compared with using silane coupling agent and HP302 emulsion to modify basalt fiber at the same time. This is because the surface of basalt fiber contains various atoms, and when only using silane coupling agent to modify it, the surface of basalt fiber cannot be completely covered by silane coupling agent molecules, resulting in poor compatibility between basalt fiber and resin interface. From the comparison of the test results of Example 1 and Comparative Example 5 (replacing carbon sponge with carbon fiber), it can be seen that the network structure of carbon sponge can exist in a continuous form in the matrix. Compared with the situation where fibers cannot contact each other, this network structure can interact with the resin matrix, thereby effectively improving the comprehensive performance of the product.

[0067] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0068] Although the embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a brake pad matching a carbon ceramic brake disc, characterized in that: The preparation method comprises: S100, preparing an impregnation solution A from raw materials including methyl silicone resin, oxide ceramics and carbide ceramics; S200, preparing an impregnation solution B from raw materials including phenolic resin, epoxy resin, basalt microfiber, mullite and vermiculite; S300, impregnating the carbon sponge with the impregnation liquid A, and obtaining a modified carbon skeleton through curing and sintering; S400, adding impregnation liquid B to the modified carbon skeleton, and obtaining the brake pad through vacuum pressure impregnation, hot pressing, heat treatment, grinding, and spraying.

2. The method for preparing a brake pad according to claim 1, characterized in that: In step S100, the methyl silicone resin is polydimethylsiloxane, the oxide ceramic is modified alumina, and the carbide ceramic is modified silicon carbide.

3. The method for preparing a brake pad according to claim 1, characterized in that: Step S100 specifically includes: adding polydimethylsiloxane to the n-hexane solution, adding modified alumina and modified silicon carbide thereto after mixing evenly, and stirring ultrasonically for 20-40 minutes to obtain an impregnation solution A.

4. The method for preparing a brake pad according to claim 1, characterized in that: The preparation process of the phenolic resin in step S200 is as follows: add phenol to the reactor, increase the temperature to 45°C, add formaldehyde after the phenol is dissolved into liquid, add sodium hydroxide after mixing evenly, increase the temperature to 85-95°C and stir for 3-6 hours to obtain a brown-red viscous phenolic resin liquid for use.

5. The method for preparing a brake pad according to claim 1, characterized in that: Step S200 specifically includes: S210, adding phenolic resin and epoxy resin into a reactor, stirring for 20-40 minutes, then adding modified basalt microfiber, mullite and vermiculite, and continuing to stir for 20-40 minutes to obtain a mixed solution; S220, placing the mixed solution in a vacuum drying oven for semi-gel treatment, adding a curing agent and an accelerator after the treatment, and mixing them evenly to obtain the impregnation solution B.

6. The method for preparing a brake pad according to claim 5, characterized in that: The preparation method of the modified basalt microfiber is: A1. Add anhydrous ethanol to deionized water, mix well, then add silane coupling agent, and stir for 4-10 minutes to obtain a silane coupling agent hydrolyzate; A2. Add HP302 emulsion to deionized water, ultrasonically disperse for 10-20 minutes, then add silane coupling agent hydrolyzate, stir for 5-15 minutes, then add basalt fiber, stir for 40-60 minutes, filter, let stand at room temperature for 24-36 hours, then put into a vacuum drying oven, dry at 105-125°C for 2-4 hours to obtain dry basalt fiber; A3. Put the dried basalt fiber into a grinder and grind it for 8-10 seconds to obtain modified basalt microfibers.

7. The method for preparing a brake pad according to claim 1, characterized in that: Step S300 specifically includes: immersing the carbon sponge in impregnation liquid A, heating it to 45-60°C in a vacuum drying oven for 2-4 hours, then heating it to 100-120°C for 4-6 hours, and finally sintering it at 1200-1400°C in a vacuum environment for 1-2 hours to obtain a modified carbon skeleton.

8. The method for preparing a brake pad according to claim 1, characterized in that: The preparation process of the carbon sponge is as follows: dispersing graphene oxide in deionized water, adding ethylenediamine, mixing evenly, adding ammonia water to adjust the pH value of the solution to a weak base, transferring the solution to a sealed container, raising the temperature to 90-100° C., heating for 10-15 hours, and then naturally cooling to room temperature to obtain graphene oxide hydrogel, performing multiple dialysis using a hydroalcohol solution, freezing at -30° C. for 10-14 hours, taking out, and freeze-drying for 48-56 hours to obtain the carbon sponge.

9. The method for preparing a brake pad according to claim 1, characterized in that: Step S400 specifically includes: immersing the obtained modified carbon skeleton into the impregnation liquid B, placing them together in the impregnation tooling, performing vacuum pressure impregnation in the impregnation furnace to obtain a preform, placing the preform on a hot pressing molding machine for hot pressing to obtain a sample, and then heat treating the sample, and obtaining the brake pad after grinding and spraying.

10. A brake pad matching a carbon ceramic brake disc, characterized in that: The brake pad is obtained by the preparation method according to any one of claims 1 to 9.

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