Graphene sponge reinforced resin friction material and preparation process

Abstract

The invention discloses a graphene sponge reinforced resin friction material and a preparation process, and relates to a friction material and a preparation process. According to the graphene sponge reinforced resin friction material and the preparation technology, through reasonable raw material formula design, the friction and wear performance, strength and toughness of an organic synthetic material are improved; meanwhile, the invention provides a preparation method which is simple in process and easy to realize industrial production. The composite material comprises phenolic resin, graphene sponge, copper fibers, graphite, molybdenum disulfide, aluminum oxide and wollastonite. Wherein the mass fraction of the phenolic resin is 20 to 25 parts, the mass fraction of the graphene sponge is 1 to 5 parts, the mass fraction of the copper fiber is 10 to 20 parts, the mass fraction of the graphite is 5 to 15 parts, the mass fraction of the molybdenum disulfide is 1 to 5 parts, the mass fraction of the aluminum oxide is 1 to 5 parts, and the mass fraction of the wollastonite is 1 to 5 parts. The invention belongs to the technical field of organic synthesis friction materials.

Description

Technical Field

[0001] The invention relates to a friction material and a preparation process, belonging to the technical field of organic synthetic friction materials. Background Art

[0002] In today's diverse industrial landscape and transportation system, friction materials act as the invisible guardians of industrial operations, playing an indispensable role in numerous critical scenarios. In automotive braking systems, the performance of friction materials directly determines driving safety and braking efficiency. In rail transit, from urban subways to high-speed trains, the smooth starting and stopping of trains, as well as their efficient braking, all depend on the reliable operation of friction materials, crucial to the safety and convenience of countless passengers.

[0003] In high-end sectors, the demands are even more stringent. In aerospace, during takeoff and landing, the friction materials of braking systems must withstand extremely high temperatures and immense pressures in a short period of time. Any performance shortcoming could lead to a serious flight accident. High-end equipment manufacturing, such as the transmission and braking systems of precision machine tools, places extremely stringent demands on friction materials for their precision retention and stability, making them difficult for traditional materials to meet.

[0004] Traditional resin-based friction materials, due to their low cost and mature manufacturing processes, have long been widely used. However, with rapid technological advancement, their drawbacks have gradually become apparent. Under frequent and high-intensity braking conditions, such as long-distance downhill descents by heavy trucks and continuous aircraft takeoffs and landings, traditional resin friction materials lack sufficient strength, resulting in increased wear and significant thermal decay. The friction coefficient plummets at high temperatures, significantly compromising braking performance and posing a significant safety hazard. Furthermore, traditional manufacturing processes result in an uneven internal structure, leading to significant batch-to-batch fluctuations in product quality and making it difficult to meet the consistency requirements of high-end applications.

[0005] To overcome these challenges, researchers have experimented with adding various reinforcing phases to resins, such as carbon fibers and aramid fibers. However, the bond between carbon fibers and resins weakens at high temperatures, leading to interfacial debonding. Aramid fiber-reinforced friction materials still fail to meet the increasingly stringent standards for wear resistance and high-temperature stability in the high-end market. Graphene sponge, an emerging carbon material, possesses a unique three-dimensional network structure, an ultra-high surface area, and excellent mechanical properties. If scientifically incorporated into resin friction material systems, it could potentially overcome existing technological bottlenecks. However, relevant research is currently lacking, and a mature and efficient preparation process is urgently needed to realize this innovative concept.

[0006] The invention patent, with publication number CN110373001B and application date August 23, 2019, discloses a method for preparing a graphene-reinforced carbon fiber composite material. The method uses a three-dimensional graphene skeleton to prepare a composite material slurry precursor through vacuum infusion, then uses a high-speed stirring ultrasound-assisted method to prepare a highly dispersed graphene resin-based composite material slurry, and finally prepares a graphene / fiber-reinforced resin-based composite material through a gradient curing and winding method. This invention solves the problem that existing methods cannot combine graphene and carbon fiber, improves the mechanical properties of fiber composite materials, increases the competitive advantage of composite materials in application fields, and provides a new preparation method for graphene-reinforced carbon fiber composite materials.

[0007] The invention patent with publication number CN110437586A and application date of August 23, 2019 discloses a method for preparing a highly dispersed graphene-enhanced epoxy resin-based composite material. The method prepares a composite material slurry precursor by vacuum infusion of a three-dimensional graphene skeleton, then prepares a highly dispersed graphene-epoxy resin-based composite material slurry by a high-speed stirring ultrasound-assisted method, and finally prepares a highly dispersed graphene-enhanced epoxy resin-based composite material by a gradient curing method. The present invention solves the problem that the existing method cannot highly disperse graphene into the epoxy resin matrix, expands its scope of application, and formulates graphene-enhanced epoxy high-temperature resin composite materials of any proportion based on the graphene-filled epoxy resin slurry. While improving the heat resistance of the epoxy resin, it also improves the mechanical properties of the epoxy resin matrix, increases the competitive advantage of the epoxy resin-based composite material in the application field, and provides a new type of highly dispersed preparation method for nanofilling.

[0008] However, none of the above documents solves the problem of how to improve the friction and wear properties, strength and toughness of organic synthetic materials. Summary of the Invention

[0009] The purpose of the present invention is to provide a graphene sponge reinforced resin friction material and a preparation process, which improves the friction and wear performance, strength and toughness of organic synthetic materials through reasonable raw material formula design; at the same time, a preparation method thereof is provided, which is simple in process and easy to realize industrial production.

[0010] The technical solution adopted by the present invention to solve the above problems is: the graphene sponge reinforced resin friction material of the present invention includes phenolic resin, graphene sponge, copper fiber, graphite, molybdenum disulfide, aluminum oxide and wollastonite; wherein the mass fraction of phenolic resin is 20 to 25 parts, the mass fraction of graphene sponge is 1 to 5 parts, the mass fraction of copper fiber is 10 to 20 parts, the mass fraction of graphite is 5 to 15 parts, the mass fraction of molybdenum disulfide is 1 to 5 parts, the mass fraction of aluminum oxide is 1 to 5 parts, and the mass fraction of wollastonite is 1 to 5 parts.

[0011] The steps of the process for preparing the graphene sponge reinforced resin friction material of the present invention include:

[0012] Step 1, pre-treating the graphene sponge;

[0013] Step 2, mixing;

[0014] Step 3: hot pressing.

[0015] Furthermore, the process of pre-treating the graphene sponge in step 1 is as follows:

[0016] Step 101: Freeze the dispersed graphene aqueous solution with a concentration of 1 to 25 mg / ml at low temperature, and obtain a porous graphene sponge by freeze-drying.

[0017] Step 102: placing the graphene sponge in an acid solution with a concentration of 0.5-2 mol / L and ultrasonically treating it at 30-60° C. for 1-3 hours;

[0018] Step 103: repeatedly rinsing with deionized water until neutral, and vacuum drying at 60-80° C. for 6-12 hours to obtain a pretreated graphene sponge;

[0019] Step 104: remove impurities on the surface of the graphene sponge through acid treatment and ultrasound, and introduce active groups on its surface to enable it to combine with other raw materials.

[0020] Furthermore, the specific process of mixing in step 2 is as follows:

[0021] The pretreated graphene sponge is cut into small pieces with a particle size of 1 to 5 mm, and is added into a high-speed mixer with phenolic resin, copper fiber, graphite, molybdenum disulfide, aluminum oxide, and wollastonite according to a mass ratio. The mixture is mixed at a speed of 100 to 300 r / min for 1 to 3 hours to obtain a uniform mixed material.

[0022] Furthermore, the hot pressing process in step 3 is as follows:

[0023] The mixed material is transferred into a mold, hot-pressed at a temperature of 150 to 200° C. and a pressure of 10 to 30 MPa for 2 to 5 hours, and demolded after cooling to room temperature to obtain the graphene sponge reinforced resin-based synthetic material.

[0024] Furthermore, the acid solution used for the acid treatment is one of hydrochloric acid solution, sulfuric acid solution or nitric acid solution.

[0025] Furthermore, the mixing speed of the high-speed mixer is 150-250 r / min, and the mixing time is 1.5-2.5 h.

[0026] Furthermore, the temperature of hot pressing is 160-180° C., the pressure is 15-25 MPa, and the hot pressing time is 3-4 hours.

[0027] The beneficial effects of the present invention are:

[0028] 1. The present invention rationally combines graphene sponge with other raw materials and utilizes the unique three-dimensional porous structure of graphene sponge to enhance the strength and toughness of the material, improve the bonding force between the components, make the friction coefficient of the organic synthetic material more stable, significantly reduce the wear rate, and effectively improve the service life and braking performance of the material;

[0029] 2. The preparation method of the present invention is simple, has low equipment requirements, and is easy to implement in industrial production. By pre-treating the graphene sponge and precisely controlling the mixing and hot pressing process parameters, the stability and consistency of the product quality can be ensured. DETAILED DESCRIPTION

[0030] Specific embodiment 1: A graphene sponge reinforced resin friction material, including phenolic resin, graphene sponge, copper fiber, graphite, molybdenum disulfide, aluminum oxide and wollastonite; wherein the mass fraction of phenolic resin is 20 to 25 parts, the mass fraction of graphene sponge is 1 to 5 parts, the mass fraction of copper fiber is 10 to 20 parts, the mass fraction of graphite is 5 to 15 parts, the mass fraction of molybdenum disulfide is 1 to 5 parts, the mass fraction of aluminum oxide is 1 to 5 parts, and the mass fraction of wollastonite is 1 to 5 parts.

[0031] Specific embodiment 2: A preparation process of a graphene sponge reinforced resin friction material, the specific steps include:

[0032] Step 1: Pre-treat the graphene sponge; the specific process is:

[0033] Step 101: Freeze the dispersed graphene aqueous solution with a concentration of 1 to 25 mg / ml at low temperature, and obtain a porous graphene sponge by freeze-drying.

[0034] Step 102: placing the graphene sponge in an acid solution with a concentration of 0.5-2 mol / L and ultrasonically treating it at 30-60° C. for 1-3 hours;

[0035] Step 103: repeatedly rinsing with deionized water until neutral, and vacuum drying at 60-80° C. for 6-12 hours to obtain a pretreated graphene sponge;

[0036] Step 104: removing impurities on the surface of the graphene sponge through acid treatment and ultrasound, and introducing active groups on the surface to enable it to combine with other raw materials;

[0037] Step 2, mixing; the specific process of mixing is:

[0038] The pretreated graphene sponge is cut into small pieces with a particle size of 1 to 5 mm, and added into a high-speed mixer with phenolic resin, copper fiber, graphite, molybdenum disulfide, aluminum oxide, and wollastonite according to a mass ratio. The mixture is mixed at a speed of 100 to 300 r / min for 1 to 3 hours to obtain a uniform mixture. The appropriate speed and mixing time can ensure that the raw materials are fully mixed and the consistency of the material properties is guaranteed;

[0039] Step 3: Hot pressing forming; the process of hot pressing forming is:

[0040] The mixed material is transferred to a mold and hot-pressed at a temperature of 150-200°C and a pressure of 10-30 MPa for 2-5 hours. After cooling to room temperature, the mold is removed to obtain the graphene sponge-reinforced resin-based synthetic material. The hot-pressing process fully solidifies the phenolic resin, tightly bonding the various components together to form a material with a specific shape and properties.

[0041] The optimal mixing parameters in step 2 are a mixing speed of 150 to 250 r / min for the high-speed mixer and a mixing time of 1.5 to 2.5 h. These mixing parameters can make the raw materials more evenly mixed.

[0042] The temperature of the hot pressing molding in step 3 is 160-180°C, the pressure is 15-25 MPa, and the hot pressing time is 3-4 hours. Such hot pressing conditions can improve production efficiency while ensuring the performance of the material.

[0043] Example

[0044] Example 1

[0045] 1. Raw material preparation: weigh 20 parts of phenolic resin, 1 part of graphene sponge, 12 parts of copper fiber, 6 parts of graphite, 3 parts of molybdenum disulfide, 4 parts of aluminum oxide, 1 part of wollastonite, and the rest of other fillers.

[0046] 2. Graphene sponge pretreatment: The graphene sponge was placed in a hydrochloric acid solution with a concentration of 0.5 mol / L, ultrasonically treated at 30°C for 3 h, then repeatedly rinsed with deionized water until neutral, and vacuum dried at 60°C for 12 h to obtain a pretreated graphene sponge.

[0047] 3. Mixing: Cut the pretreated graphene sponge into small pieces with a particle size of 1 mm, add it into a high-speed mixer with other raw materials, and mix it at a speed of 100 r / min for 3 hours to obtain a uniform mixture.

[0048] 4. Hot pressing: The mixed material is transferred to a mold and hot pressed at a temperature of 150°C and a pressure of 10 MPa for 5 hours. After cooling to room temperature, the mold is demolded to obtain a graphene sponge-reinforced resin-based synthetic material.

[0049] Example 2

[0050] 1. Raw material preparation: weigh 23 parts of phenolic resin, 2 parts of graphene sponge, 15 parts of copper fiber, 8 parts of graphite, 2 parts of molybdenum disulfide, 3 parts of aluminum oxide, 2 parts of wollastonite, and the rest of other fillers.

[0051] 2. Graphene sponge pretreatment: The graphene sponge was placed in a 1 mol / L sulfuric acid solution, ultrasonically treated at 40°C for 2 h, then repeatedly rinsed with deionized water until neutral, and vacuum dried at 70°C for 8 h to obtain a pretreated graphene sponge.

[0052] 3. Mixing: Cut the pretreated graphene sponge into small pieces with a particle size of 3 mm, add it into a high-speed mixer with other raw materials, and mix it at a speed of 150 r / min for 2.5 hours to obtain a uniform mixture.

[0053] 4. Hot pressing: The mixed material is transferred to a mold and hot pressed at a temperature of 160°C and a pressure of 15 MPa for 4 hours. After cooling to room temperature, the mold is demolded to obtain a graphene sponge-reinforced resin-based synthetic material.

[0054] Example 3

[0055] 1. Raw material preparation: weigh 25 parts of phenolic resin, 3 parts of graphene sponge, 18 parts of copper fiber, 10 parts of graphite, 1 part of molybdenum disulfide, 2 parts of aluminum oxide, 3 parts of wollastonite, and the rest of other fillers.

[0056] 2. Graphene sponge pretreatment: The graphene sponge was placed in a nitric acid solution with a concentration of 1.5 mol / L, ultrasonically treated at 50°C for 1.5 h, then repeatedly rinsed with deionized water until neutral, and vacuum dried at 80°C for 6 h to obtain a pretreated graphene sponge.

[0057] 3. Mixing: Cut the pretreated graphene sponge into small pieces with a particle size of 4 mm, add it into a high-speed mixer with other raw materials, and mix it at a speed of 250 r / min for 1.5 hours to obtain a uniform mixture.

[0058] 4. Hot pressing: The mixed material is transferred to a mold and hot pressed at a temperature of 180°C and a pressure of 25 MPa for 3 hours. After cooling to room temperature, the mold is demolded to obtain a graphene sponge-reinforced resin-based synthetic material.

[0059] Example 4

[0060] 1. Raw material preparation: weigh 28 parts of phenolic resin, 4 parts of graphene sponge, 20 parts of copper fiber, 12 parts of graphite, 1 part of molybdenum disulfide, 1 part of aluminum oxide, 4 parts of wollastonite, and the rest of other fillers.

[0061] 2. Graphene sponge pretreatment: The graphene sponge was placed in a 2 mol / L hydrochloric acid solution, ultrasonically treated at 60°C for 1 h, then repeatedly rinsed with deionized water until neutral, and vacuum dried at 80°C for 6 h to obtain a pretreated graphene sponge.

[0062] 3. Mixing: Cut the pretreated graphene sponge into small pieces with a particle size of 5 mm, add it into a high-speed mixer with other raw materials, and mix it at a speed of 300 r / min for 1 hour to obtain a uniform mixture.

[0063] 4. Hot pressing: The mixed material is transferred to a mold and hot pressed at a temperature of 200°C and a pressure of 30 MPa for 2 hours. After cooling to room temperature, the mold is demolded to obtain a graphene sponge-reinforced resin-based synthetic material.

[0064] Comparative Example 1

[0065] 1. Raw material preparation: weigh 25 parts of phenolic resin, 20 parts of copper fiber, 8 parts of graphite, 2 parts of molybdenum disulfide, 3 parts of aluminum oxide, and 3 parts of wollastonite (without adding graphene sponge) by mass.

[0066] 2. Mixing: Add the above raw materials into a high-speed mixer and mix at a speed of 150 r / min for 2.5 h to obtain a mixed material.

[0067] 3. Hot pressing: The mixed material was transferred to a mold and hot pressed at a temperature of 160°C and a pressure of 15 MPa for 4 h. After cooling to room temperature, the mold was demolded to obtain a synthetic material for comparison.

[0068] Comparative Example 2

[0069] 1. Raw material preparation: weigh 25 parts of phenolic resin, 10 parts of graphene sponge, 20 parts of copper fiber, 8 parts of graphite, 2 parts of molybdenum disulfide, 3 parts of aluminum oxide, and 3 parts of wollastonite (graphene sponge is beyond the scope of the present invention).

[0070] 2. Graphene sponge pretreatment: same as Example 2.

[0071] 3. Mixing: Same as Example 2.

[0072] 4. Hot pressing: same as in Example 2.

[0073] Performance Testing

[0074] The friction materials prepared in Examples 1-4 and Comparative Examples 1-2 were tested for their performance, and the test results are as follows:

[0075] category Friction coefficient fluctuation range <![CDATA[Wear rate (cm 3 / MJ)]]> Compressive strength (MPa) Example 1 ±0.04 0.07 38 Example 2 ±0.05 0.10 35 Example 3 ±0.04 0.10 42 Example 4 ±0.03 0.09 36 Comparative Example 1 ±0.08 0.16 32 Comparative Example 2 ±0.12 0.14 28

[0076] 1. Friction Coefficient Stability: The friction coefficient of the materials was tested at different pressures and speeds using a constant-speed friction tester. The friction coefficients of Examples 1-4 fluctuated within ±0.05, while the friction coefficient of Comparative Example 1 fluctuated within ±0.1. Due to the excessively high graphene sponge content in Comparative Example 2, the friction coefficient fluctuated within ±0.12.

[0077] This shows that the friction coefficient of the material added with an appropriate amount of graphene sponge in the present invention is more stable.

[0078] 2. Wear rate: Wear test was carried out by wear tester. The wear rate of the materials in Examples 1-4 was between 0.07-0.1 cm 3 / MJ, the wear rate of comparative example 1 is 0.16cm 3 / MJ, the wear rate of comparative example 2 is 0.14cm 3 / MJ. This shows that the material wear rate of the present invention is lower.

[0079] 3. Compressive Strength: The compressive strength of the materials was tested using a universal material testing machine. The compressive strength of the materials in Examples 1-4 ranged from 35 to 42 MPa, while the compressive strength of Comparative Example 1 was 38 MPa. Due to the aggregation of the graphene sponge, the compressive strength of Comparative Example 2 was 28 MPa. The material of the present invention has a higher compressive strength.

[0080] In summary, the present invention successfully prepares a graphene sponge-reinforced resin-based synthetic material with excellent performance through a reasonable raw material formula and preparation process, which has good application prospects.

[0081] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement of the above embodiments made according to the technical essence of the present invention, within the spirit and principles of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A graphene sponge reinforced resin friction material, characterized in that: The invention comprises phenolic resin, graphene sponge, copper fiber, graphite, molybdenum disulfide, aluminum oxide and wollastonite; wherein the mass proportion of the phenolic resin is 20 to 25 parts, the mass proportion of the graphene sponge is 1 to 5 parts, the mass proportion of the copper fiber is 10 to 20 parts, the mass proportion of the graphite is 5 to 15 parts, the mass proportion of the molybdenum disulfide is 1 to 5 parts, the mass proportion of the aluminum oxide is 1 to 5 parts, and the mass proportion of the wollastonite is 1 to 5 parts.

2. A process for preparing a graphene sponge reinforced resin friction material, characterized in that: The specific steps include: Step 1, pre-treating the graphene sponge; Step 2, mixing; Step 3: hot pressing.

3. The process for preparing a graphene sponge reinforced resin friction material according to claim 2, characterized in that: The process of pre-treating the graphene sponge in step 1 is as follows: Step 101: Freeze the dispersed graphene aqueous solution with a concentration of 1 to 25 mg / ml at low temperature, and obtain a porous graphene sponge by freeze-drying. Step 102: placing the graphene sponge in an acid solution with a concentration of 0.5-2 mol / L and ultrasonically treating it at 30-60° C. for 1-3 hours; Step 103: repeatedly rinsing with deionized water until neutral, and vacuum drying at 60-80° C. for 6-12 hours to obtain a pretreated graphene sponge; Step 104: remove impurities on the surface of the graphene sponge through acid treatment and ultrasound, and introduce active groups on its surface to enable it to combine with other raw materials.

4. The process for preparing a graphene sponge reinforced resin friction material according to claim 2, characterized in that: The specific process of mixing in step 2 is: The pretreated graphene sponge is cut into small pieces with a particle size of 1 to 5 mm, and is added into a high-speed mixer with phenolic resin, copper fiber, graphite, molybdenum disulfide, aluminum oxide, and wollastonite according to a mass ratio. The mixture is mixed at a speed of 100 to 300 r / min for 1 to 3 hours to obtain a uniform mixed material.

5. The process for preparing a graphene sponge reinforced resin friction material according to claim 2, characterized in that: The process of hot pressing in step 3 is as follows: The mixed material is transferred into a mold, hot-pressed at a temperature of 150 to 200° C. and a pressure of 10 to 30 MPa for 2 to 5 hours, and demolded after cooling to room temperature to obtain the graphene sponge reinforced resin-based synthetic material.

6. The process for preparing a graphene sponge reinforced resin friction material according to claim 3, characterized in that: The acid solution used for the acid treatment is one of hydrochloric acid solution, sulfuric acid solution or nitric acid solution.

7. The process for preparing a graphene sponge reinforced resin friction material according to claim 4, characterized in that: The mixing speed of the high-speed mixer is 150-250 r / min, and the mixing time is 1.5-2.5 h.

8. The process for preparing a graphene sponge reinforced resin friction material according to claim 5, characterized in that: The temperature of hot pressing is 160-180°C, the pressure is 15-25 MPa, and the hot pressing time is 3-4 hours.