A friction material and method produced using carbon-carbon scraps

Abstract

The present invention discloses a friction material and method produced using carbon-carbon scraps, including 30 to 45 parts of carbon-carbon particles, 10 to 15 parts of carbon fiber powder, 3 to 10 parts of 6818 resin, 3 to 10 parts of nitrile rubber powder, 10 to 15 parts of barium sulfate, 1 to 2.5 parts of zircon powder, 3 to 10 parts of mineral fiber, 3 to 10 parts of calcium carbonate whiskers, 3 to 10 parts of mica, 3 to 5 parts of collagen fiber, and 0.2 to 1 part of zinc stearate; the friction material formed on the basis of carbon fiber in the present invention has excellent high-temperature stability; after the carbon-carbon particles are graphitized at high temperature, they have self-lubricity; the powdery carbon fiber has fiber reinforcement. Therefore, on the basis of traditional friction materials, adding carbon fiber can simultaneously replace raw materials such as graphite and reinforcing fibers, and at the same time can reduce the wear rate and increase the friction coefficient.

Description

Technical Field

[0001] The present invention belongs to the technical field of friction materials, and relates to friction materials and preparation methods, in particular to a friction material and method produced using carbon-carbon scraps. Background Art

[0002] Friction materials are characterized by good friction coefficients and wear resistance, and at the same time have certain heat resistance and mechanical strength, and can meet the performance requirements of the transmission and braking of vehicles or machinery. They are widely used in power transmission or braking and deceleration.

[0003] Due to its excellent properties, carbon fiber is known as "black gold" and "king of new materials". With the increasingly wide application of carbon fiber composites, the amount of its scrap waste is also increasing. The recycling of scrap waste has currently become a new problem faced by the industrial community and society. Generally speaking, there are several methods for recycling carbon fiber scrap. One is to incinerate carbon fiber waste and utilize the thermal energy generated by its combustion. However, this process will release a large amount of toxic gases, and at the same time, burying the ash after combustion will cause secondary pollution to the soil. Another is to make carbon fiber waste or carbon fiber composite waste into particles, fine powders, etc. through methods such as shredding and grinding for utilization. The materials processed in this way are usually only used as building fillers, paving materials, cement raw materials, etc., and the added value generated is not high.

[0004] With the continuous improvement of highway conditions, the driving speed of automobiles has increased. The requirements for the friction and wear performance of friction materials are getting higher and higher. The friction and wear performance of ordinary friction materials cannot meet the improvement of automobile performance, mainly reflected in the unstable friction coefficient (thermal recession) and large wear during high-temperature braking of friction materials. Since carbon-carbon composites have high-temperature stability, the present invention can effectively improve the friction and wear performance of friction materials and further improve the braking performance of automobiles. Summary of the Invention

[0005] In order to solve the above problems, the present invention first provides a friction material produced using carbon-carbon scraps. The friction material formed on the basis of carbon fiber has excellent high-temperature stability; after high-temperature graphitization, the carbon-carbon particles have self-lubricating properties; and the powdered carbon fiber has fiber-reinforcing properties. Therefore, on the basis of traditional friction materials, adding carbon fiber can simultaneously replace raw materials such as graphite and reinforcing fibers, and at the same time can reduce the wear rate and increase the friction coefficient.

[0006] The present invention provides high-performance friction materials for the market, which can improve the friction and wear performance of friction materials, solve the thermal recession phenomenon of braking performance during the braking process, increase the service life of brake pads, improve braking safety, and reduce the accident frequency caused by braking.

[0007] The present invention improves the shortcoming problems in the recycling of existing carbon fiber preform waste, and realizes the product value of low cost, high performance and high yield.

[0008] The present invention also provides a method for producing the above-mentioned friction material.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A friction material produced from carbon-carbon scraps, the friction material comprises by weight: 10 parts to 60 parts of carbon-carbon particles, 1 part to 20 parts of carbon fiber powder, 1 part to 15 parts of 6818 resin, 1 part to 20 parts of nitrile rubber powder, 5 parts to 25 parts of barium sulfate, 1 part to 5.5 parts of zircon powder, 1 part to 15 parts of mineral fiber, 1 part to 15 parts of calcium carbonate whisker, 1 part to 15 parts of mica, 1 part to 10 parts of collagen fiber and 0.2 part to 1 part of zinc stearate; wherein, the carbon-carbon particles are made from carbon fiber scraps.

[0011] As a preferred embodiment of the present invention, the friction material comprises by weight: 20 parts to 50 parts of carbon-carbon particles, 5 parts to 15 parts of carbon fiber powder, 3 parts to 15 parts of 6818 resin, 3 parts to 20 parts of nitrile rubber powder, 10 parts to 25 parts of barium sulfate, 1 part to 4.5 parts of zircon powder, 3 parts to 15 parts of mineral fiber, 3 parts to 15 parts of calcium carbonate whisker, 3 parts to 15 parts of mica, 3 parts to 10 parts of collagen fiber and 0.2 part to 1 part of zinc stearate.

[0012] As a preferred embodiment of the present invention, the friction material comprises by weight: 30 parts to 45 parts of carbon-carbon particles, 10 parts to 15 parts of carbon fiber powder, 3 parts to 10 parts of 6818 resin, 3 parts to 10 parts of nitrile rubber powder, 10 parts to 15 parts of barium sulfate, 1 part to 2.5 parts of zircon powder, 3 parts to 10 parts of mineral fiber, 3 parts to 10 parts of calcium carbonate whisker, 3 parts to 10 parts of mica, 3 parts to 5 parts of collagen fiber and 0.2 part to 1 part of zinc stearate.

[0013] The present invention also discloses a method for producing a friction material from carbon-carbon scraps, the method comprising the following steps:

[0014] 1) Impregnation of carbon fiber preform scraps: placing carbon fiber scraps in asphalt for impregnation treatment;

[0015] 2) Carbonizing the impregnated carbon fiber preform scraps obtained in step 1) to obtain a carbonized preform;

[0016] 3) Graphitizing the carbonized preform obtained in step 2);

[0017] 4) Processing the graphitized preform obtained in step 3) with a crusher and a ball mill to obtain carbon-carbon particles;

[0018] 5) Screen and powder the carbon chips in the processing of step 4) to obtain carbon fiber powder;

[0019] 6) Mix the carbon-carbon particles obtained in step 4), the carbon fiber powder obtained in step 5), 6818 resin, nitrile rubber powder, barium sulfate, zircon powder, mineral fiber, calcium carbonate whisker, mica, collagen fiber, and zinc stearate to obtain a friction material.

[0020] As a preferred embodiment of the present invention, in step 1), carbon fiber preform scraps are used. It is required that the tensile strength of the original carbon fiber filaments of the preform should reach above 3.5 Gpa, and the density after impregnation in asphalt should reach 0.7 g / cm 3 ~1.0 g / cm 3 .

[0021] As a preferred embodiment of the present invention, in step 2), the carbonization temperature is 1500 °C to 1750 °C.

[0022] As a preferred embodiment of the present invention, in step 3), the conditions for graphitization treatment are: temperature 1700 °C to 1900 °C, time 10 h to 30 h.

[0023] As a preferred embodiment of the present invention, in step 4), the diameter of the carbon-carbon particles is 50 mesh.

[0024] As a preferred embodiment of the present invention, in step 5), the particle size of the carbon fiber powder is 10 mesh to 30 mesh.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1) The present invention provides a high-performance friction material for the market, which can improve the friction and wear performance of the friction material, solve the problem of thermal recession of the braking performance during braking, improve the service life of the brake pads, improve the braking safety, and reduce the accident frequency caused by braking.

[0027] 2) The present invention improves the shortcoming problem of the recycling of existing carbon fiber preform waste, and realizes the product value of low cost, high performance, and high yield.

[0028] 3) The formula of the present invention is reasonable and the process flow is scientific.

[0029] 4) The carbon fiber reinforced base friction material of the present invention can be obtained during the production of carbon-carbon products, reducing the solid waste generated during the production of carbon-carbon products. Therefore, the manufacturing cost is low, which not only reduces costs but also saves energy.

[0030] 5) The carbon fiber reinforced friction material of the present invention can replace traditional graphite materials and other reinforcing fibers, and can be widely used in the production process of brake materials. At the same time, the friction braking performance of the friction material produced by the method of the present invention has been greatly improved, and the service life is more than 3 times the original life. Detailed implementation mode

[0031] The following will combine the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0032] The present invention first provides a friction material produced from carbon-carbon scraps. The friction material includes, by weight: 30 to 45 parts of carbon-carbon particles, 10 to 15 parts of carbon fiber powder, 3 to 10 parts of 6818 resin, 3 to 10 parts of nitrile rubber powder, 10 to 15 parts of barium sulfate, 1 to 2.5 parts of zircon powder, 3 to 10 parts of mineral fiber, 3 to 10 parts of calcium carbonate whiskers, 3 to 10 parts of mica, 3 to 5 parts of collagen fiber, and 0.2 to 1 part of zinc stearate; wherein, the carbon-carbon particles are made from carbon fiber scraps.

[0033] The present invention also discloses a method for producing a friction material from carbon-carbon scraps, and the method includes the following steps:

[0034] 1) Impregnation of carbon fiber preform scraps: Place the carbon fiber scraps in asphalt for impregnation treatment;

[0035] 2) Carbonize the impregnated carbon fiber preform scraps obtained in step 1) to obtain a carbonized preform;

[0036] 3) Graphitize the carbonized preform obtained in step 2);

[0037] 4) Process the graphitized preform obtained in step 3) with a crusher and a ball mill to obtain carbon-carbon particles;

[0038] 5) Screen the carbon chips in the processing in step 4) to obtain carbon fiber powder;

[0039] 6) Mix the carbon-carbon particles obtained in step 4), the carbon fiber powder obtained in step 5), 6818 resin, nitrile rubber powder, barium sulfate, zircon powder, mineral fiber, calcium carbonate whiskers, mica, collagen fiber, and zinc stearate to obtain a friction material.

[0040] The following analyzes the friction performance of the carbon fiber reinforced friction material:

[0041] 1. Carbon fiber reinforced base

[0042] To improve the friction performance of brake products, we have conducted various studies, mainly to find a material that reduces wear. The current anti-wear material used in brake products is flake graphite. The main functions of flake graphite during the friction and wear process are: (1) enhancing the adhesion on the counterface; (2) aggregating at the friction interface and bearing the friction.

[0043] X-ray photoelectron spectroscopy analysis during counterface friction shows that FeS, FeSO4 and other components are generated when the cast iron disc rubs against the friction plate. These components increase the bonding of the counterface, thereby increasing the wear resistance and improving the wear resistance. After adding the carbon fiber reinforced base, the formed bond on the surface is thin and uniform. The fiber characteristics of carbon fiber and the self-lubricity after graphitization improve the anti-wear ability of the friction material.

[0044] The morphology and hardness of the carbon fiber reinforced base also affect the friction performance of the friction material. Friction materials are respectively pressed with granular, layered and fibrous fillers. When reinforced with fibers and particulate fillers with higher hardness, during the friction process, the load is first borne by the filler particles or fibers with higher strength and hardness.

[0045] 2. Sliding speed

[0046] The influence of sliding speed on friction performance is relatively complex. The initial wear volume values of the material are the same at different sliding speeds, and the wear volume decreases as the speed increases. The sliding speed affects the friction behavior through the strain rate and the heating rate. According to the delamination theory, the wear gradually increases as the speed increases. After the speed reaches a certain level, the temperature effect becomes the main factor. The frictional heat generated at high speed increases the reactivity of the transfer film, and the molecular chain structure is more likely to change to a stable structure, which is beneficial to reducing friction and wear. The influence of sliding speed is greater than that of load. A large amount of heat is generated during the friction process, thus increasing the temperature of the friction surface. The higher the speed, the higher the temperature. When the temperature reaches the glass transition temperature of the composition, its viscosity increases, thereby increasing the friction coefficient, and the wear also increases with the increase of the sliding speed. Then, as the temperature continues to rise, the high elastic state gradually changes to the viscous flow state, and the viscosity gradually decreases, which will cause the friction coefficient to drop rapidly.

[0047] 3. Load

[0048] The load affects the frictional force through the size of the contact area and the deformation state. As the load increases, the friction coefficient first decreases sharply and then stabilizes after reaching a certain level. The wear volume increases with the increase of the load. When the load is low, the surface contact of the friction pair material is in an elastic or viscoelastic state, and the actual contact area is proportional to Pn, where N = 2 / 3 - 1. When the load increases to a certain extent, the contact state of the micro-protrusions completely turns into a plastic contact state. At this time, the increase in area depends entirely on plastic deformation, and the area changes proportionally with the load. The friction coefficient does not change with the load and remains roughly constant. In the initial stage of wear, the transfer film is not completely formed. The increase in load leads to an increase in the plowing of the hard micro-protrusions on the metal surface against the composition surface, resulting in an increase in both the frictional force and wear.

[0049] 4. Temperature

[0050] Temperature is one of the main factors affecting the tribological properties of the composition. The heat generated during the friction process raises the temperature, changing the properties of the surface layer and the interaction and failure conditions on the surface during the friction process. Therefore, the friction coefficient also changes accordingly. The influence of temperature on the friction and wear properties of organic materials mainly has two aspects: on the one hand, the frictional heat generated during the friction process continuously raises the temperature of the friction surface, causing the organic material on the friction surface to change from a glassy state to a high elastic state and a viscous flow state, resulting in corresponding changes in the friction coefficient and wear rate. On the other hand, the friction temperature rise causes complex tribochemical reactions in the organic material, thus changing the molecular structure and further changing the tribological characteristics of the organic material. Under dry friction conditions, the tribological properties at room temperature and high temperature were studied. It was found that above 400 °C, mainly linear, branched and cross-linked structures are formed with the increase of the sintering temperature. The change of the linear structure of the carbon fiber composition is beneficial to the improvement of the wear resistance of the material, and the formed sample at 670 °C shows certain self-reinforcing characteristics.

[0051] Example 1

[0052] The method for producing a friction material using carbon-carbon scraps provided in this example includes the following steps:

[0053] 1) Impregnation of carbon fiber preform scraps: Place carbon fiber scraps with a tensile strength of 3.5 Gpa or more in asphalt for impregnation treatment. The density after impregnation in asphalt should reach 0.7 g / cm 3 ~1.0 g / cm 3 ;

[0054] 2) Carbonize the impregnated carbon fiber preform scraps obtained in step 1) to obtain a carbonized preform blank, and the carbonization temperature is 1500 °C;

[0055] 3) Graphitize the carbonized preform blank obtained in step 2), and the graphitization conditions are: temperature 1700 °C, time 10 h;

[0056] 4) The graphitized green body obtained in step 3) is processed by a crusher and a ball mill to obtain carbon-carbon particles, and the diameter of the carbon-carbon particles is 50 mesh;

[0057] 5) The carbon chips in the processing of step 4) are sieved to obtain carbon fiber powder, and the particle size of the carbon fiber powder is 10 mesh to 30 mesh;

[0058] 6) The carbon-carbon particles obtained in step 4), the carbon fiber powder obtained in step 5), 6818 resin, nitrile rubber powder, barium sulfate, zircon powder, mineral fiber, calcium carbonate whisker, mica, collagen fiber, and zinc stearate are mixed to obtain a friction material.

[0059] Among them, by weight, there are 30 parts of carbon-carbon particles, 10 parts of carbon fiber powder, 3 parts of 6818 resin, 3 parts of nitrile rubber powder, 10 parts of barium sulfate, 1 part of zircon powder, 3 parts of mineral fiber, 3 parts of calcium carbonate whisker, 3 parts of mica, and 3 parts of collagen fiber

[0060] and 0.2 part of zinc stearate.

[0061] Example 2

[0062] The method for producing a friction material using carbon-carbon scraps provided in this example includes the following steps:

[0063] 1) Impregnation of carbon fiber preform scraps: Carbon fiber scraps with a tensile strength of 3.5 Gpa or more are placed in asphalt for impregnation treatment, and the density after impregnation in asphalt should reach 0.7 g / cm 3 ~1.0 g / cm 3 ;

[0064] 2) The impregnated carbon fiber preform scraps obtained in step 1) are carbonized to obtain a carbonized preform, and the carbonization temperature is 1680 °C;

[0065] 3) The carbonized preform obtained in step 2) is graphitized, and the graphitization conditions are: temperature 1850 °C, time 20 h;

[0066] 4) The graphitized green body obtained in step 3) is processed by a crusher and a ball mill to obtain carbon-carbon particles, and the diameter of the carbon-carbon particles is 50 mesh;

[0067] 5) The carbon chips in the processing of step 4) are sieved to obtain carbon fiber powder, and the particle size of the carbon fiber powder is 10 mesh to 30 mesh;

[0068] 6) Mix the carbon-carbon particles obtained in step 4), the carbon fiber powder obtained in step 5), 6818 resin, nitrile rubber powder, barium sulfate, zircon powder, mineral fiber, calcium carbonate whisker, mica, collagen fiber, and zinc stearate to obtain a friction material.

[0069] Among them, by weight, there are 36 parts of carbon-carbon particles, 12 parts of carbon fiber powder, 5 parts of 6818 resin, 8 parts of nitrile rubber powder, 12 parts of barium sulfate, 1.5 parts of zircon powder, 6 parts of mineral fiber, 5 parts of calcium carbonate whisker, 7 parts of mica, 4 parts of collagen fiber, and 0.8 part of zinc stearate.

[0070] Example 3

[0071] The method for producing a friction material using carbon-carbon waste materials provided in this example includes the following steps:

[0072] 1) Impregnation of carbon fiber preform waste materials: Place carbon fiber waste materials with a tensile strength of 3.5 Gpa or more in asphalt for impregnation treatment. The density after impregnation in asphalt should reach 0.7 g / cm 3 ~1.0 g / cm 3 ;

[0073] 2) Carbonize the impregnated carbon fiber preform waste materials obtained in step 1) to obtain a carbonized preform blank, and the carbonization temperature is 1750 °C;

[0074] 3) Graphitize the carbonized preform blank obtained in step 2). The conditions for graphitization are: temperature 1900 °C, time 30 h;

[0075] 4) Process the graphitized blank obtained in step 3) with a crusher and a ball mill to obtain carbon-carbon particles, and the diameter of the carbon-carbon particles is 50 mesh;

[0076] 5) Screen the carbon chips in the processing of step 4) to obtain carbon fiber powder, and the particle size of the carbon fiber powder is 10 mesh to 30 mesh;

[0077] 6) Mix the carbon-carbon particles obtained in step 4), the carbon fiber powder obtained in step 5), 6818 resin, nitrile rubber powder, barium sulfate, zircon powder, mineral fiber, calcium carbonate whisker, mica, collagen fiber, and zinc stearate to obtain a friction material.

[0078] Among them, by weight, there are 45 parts of carbon-carbon particles, 15 parts of carbon fiber powder, 10 parts of 6818 resin, 10 parts of nitrile rubber powder, 15 parts of barium sulfate, 2.5 parts of zircon powder, 10 parts of mineral fiber, 10 parts of calcium carbonate whisker, 10 parts of mica, 5 parts of collagen fiber, and 1 part of zinc stearate.

[0079] The friction materials obtained in Examples 1-3 were used to produce brake pad products according to the following process, and the production process is as follows:

[0080] Batching → Mixing → Pressing → Curing → Grinding → Painting → Labeling → Finished product.

[0081] The friction performance of the brake pad products produced in Examples 1-3 was tested using a Krauss and a constant speed friction testing machine, as shown in Tables 1 and 2.

[0082] Table 1. Krauss test results

[0083]

[0084] Table 2. Constant speed test results

[0085] Density g / cm Average coefficient of friction Highest coefficient of friction Lowest coefficient of friction Volatility % Weight wear g Total weight friction rate Loss rate % Swelling rate % Example 1 2.05 0.318 0.4 0.24 25.0 0.37 0.97 2.22 100.0 Example 2 2.09 0.323 0.38 0.29 13.4 0.51 1.29 2.79 100.0 Example 3 2.09 0.326 0.42 0.26 23.5 0.39 0.98 2.19 100.0

[0086] As can be seen from Tables 1 and 2, the results of the friction and wear characteristics of the present invention show that the use of carbon fiber reinforced base friction materials reduces the wear amount by 30% under the same braking conditions and increases the product life by 3 times.

[0087] The above is only a preferred embodiment of the present invention, and does not impose any formal or substantial limitations on the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the method of the present invention, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any equivalent changes made by those skilled in the art who are familiar with this specialty without departing from the spirit and scope of the present invention, when using the technical content disclosed above, are all equivalent embodiments of the present invention; at the same time, any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for producing a friction material using carbon-carbon scraps, characterized in that, The method includes the following steps: 1) Impregnation of carbon fiber preform scraps: Impregnate the carbon fiber scraps in asphalt; the tensile strength of the preform carbon fiber precursor should reach above 3.5Gpa, and the density after impregnation in asphalt should reach 0.7g / cm 3 ~1.0g / cm 3 ; 2) Carbonize the corner scraps of the impregnated carbon fiber preform obtained in step 1) to obtain a carbonized preform; 3) Perform graphitization treatment on the carbonized preform obtained in step 2); 4) Process the graphitized preform obtained in step 3) with a crusher and a ball mill to obtain carbon-carbon particles with a diameter of 50 mesh; 5) Perform sieving on the carbon chips in the processing of step 4) to obtain carbon fiber powder with a particle size of 10 mesh to 30 mesh; 6) Mix the carbon-carbon particles obtained in step 4), the carbon fiber powder obtained in step 5), 6818 resin, nitrile rubber powder, barium sulfate, zircon powder, mineral fiber, calcium carbonate whisker, mica, collagen fiber, and zinc stearate to obtain a friction material; The friction material includes, by weight parts: 30 parts to 45 parts of carbon-carbon particles, 10 parts to 15 parts of carbon fiber powder, 3 parts to 10 parts of 6818 resin, 3 parts to 10 parts of nitrile rubber powder, 10 parts to 15 parts of barium sulfate, 1 part to 2.5 parts of zircon powder, 3 parts to 10 parts of mineral fiber, 3 parts to 10 parts of calcium carbonate whisker, 3 parts to 10 parts of mica, 3 parts to 5 parts of collagen fiber, and 0.2 parts to 1 part of zinc stearate.

2. The method for producing a friction material using carbon-carbon scraps according to claim 1, characterized in that, In step 2), the carbonization temperature is 1500 °C to 1750 °C.

3. The method for producing a friction material using carbon-carbon scraps according to claim 1, characterized in that, In step 3), the conditions for graphitization treatment are: temperature 1700 °C to 1900 °C, and time 10 h to 30 h.

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