High-temperature-resistant friction material as well as preparation method and application thereof

Abstract

The invention provides a high-temperature-resistant friction material as well as a preparation method and application thereof, and belongs to the technical field of braking systems. The high-temperature-resistant friction material comprises the following components in parts by weight: 18-20 parts of modified phenolic resin, 3-4 parts of nitrile rubber, 2-3 parts of vanadine powder, 10-12 parts of barium sulfate, 1-2 parts of iron oxide red, 3-5 parts of iron oxide black, 36-41 parts of sepiolite fabric, 12-16 parts of glass fiber, 2-3 parts of tire powder and 3-5 parts of crystalline flake graphite. The high-temperature-resistant friction material provided by the invention is stable in friction coefficient in a high-temperature environment, low in wear rate and good in impact strength and hardness.

Description

Technical Field

[0001] The present invention belongs to the technical field of braking systems, and particularly relates to a high-temperature resistant friction material, a preparation method and an application thereof. Background Art

[0002] Friction materials are component materials applied to power machinery and rely on friction to perform braking and transmission functions. The characteristics of this material are that while having good friction coefficient and wear resistance, it also has certain heat resistance and mechanical strength, and can meet the requirements of the transmission and braking performance of vehicles or industrial equipment. Compared with automotive brakes, the operating environment of industrial brakes is more complex, mainly manifested

[0003] in the following aspects:

[0004] 1) Being in a high-temperature and humid working environment for a long time.

[0005] 2) Being greatly affected by climate changes during outdoor operations.

[0006] 3) Different from automotive brakes that are often in a relaxed state, industrial brakes are often in a braking state. The long-term high temperature and high pressure are likely to have physical or chemical effects such as diffusion and replacement between the friction plate and the mating surface.

[0007] For the above reasons, non-metallic materials are basically used in the formulation design of industrial brake linings. Generally, industrial brakes have low requirements for the high-temperature resistance of friction plates. The conventional requirement is that the friction coefficient ≥ 0.4 at 200 °C. However, under certain special working conditions, the temperature of the friction plate may reach 300 °C. At this temperature, the resin and rubber as adhesives have entered the decomposition region, which will seriously affect the performance indicators of the friction plate. Summary of the Invention

[0008] In view of this, the present invention provides a high-temperature resistant friction material, a preparation method and an application thereof. The high-temperature resistant friction material has a stable friction coefficient, a low wear rate, and good impact strength and hardness in a high-temperature environment.

[0009] The present invention provides a high-temperature resistant friction material, comprising the following components in parts by weight: 18 - 20 parts of modified phenolic resin, 3 - 4 parts of nitrile rubber, 2 - 3 parts of bauxite powder, 10 - 12 parts of barium sulfate, 1 - 2 parts of iron oxide red, 3 - 5 parts of iron oxide black, 36 - 41 parts of sepiolite wool, 12 - 16 parts of glass fiber, 2 - 3 parts of tire powder, and 3 - 5 parts of flake graphite; the modified phenolic resin is cashew shell oil modified phenolic resin.

[0010] Preferably, the particle size of the nitrile rubber ≥ 300 mesh, and the acrylonitrile content in the nitrile rubber is 30 - 35 wt%.

[0011] Preferably, the particle size of the modified phenolic resin is ≥200 mesh; the particle size of the tire powder is 20 - 40 mesh, and the particle size of the flake graphite is ≥30 mesh; the particle sizes of the bauxite powder, barium sulfate, iron oxide red, and iron oxide black are all ≥500 mesh.

[0012] Preferably, the fiber length of the sepiolite wool is ≤3 mm; the length of the glass fiber is 2 - 3 mm.

[0013] Preferably, the dry friction coefficient of the high-temperature resistant friction material at 350 °C is 0.40 - 0.45; the impact strength is 4.9 - 5.3 dJ / cm 2 ; the hardness is HRS90 - 95.

[0014] The present invention provides a preparation method of the high-temperature resistant friction material described in any one of the above, including the following steps:

[0015] 1) Mix the modified phenolic resin, nitrile rubber, bauxite powder, barium sulfate, iron oxide red, iron oxide red, sepiolite wool, glass fiber, tire powder, and flake graphite to obtain a mixed material;

[0016] 2) Hot press the mixed material to obtain a semi-finished product;

[0017] 3) Cure the semi-finished product to obtain the high-temperature resistant friction material.

[0018] Preferably, when performing hot pressing in step 2), the hot pressing temperature is 155 - 165 °C, the pressure is 28 - 32 Mpa, and the holding pressure time is calculated according to the forming thickness of 1 mm / min.

[0019] Preferably, in step 3), a two-stage heating method is adopted for curing treatment. First, heat from room temperature to 135 - 145 °C in 0.8 - 1.2 h and hold at 135 - 145 °C for 1.8 - 2.2 h; then heat from 135 - 145 °C to 165 - 175 °C in 0.8 - 1.2 h and hold at 165 - 175 °C for 8 - 10 h.

[0020] The present invention provides the application of the high-temperature resistant friction material described in any one of the above in industrial brakes.

[0021] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0022] The present invention provides a high-temperature resistant friction material. By controlling the components and addition amounts of the high-temperature resistant friction material, and through the synergistic cooperation among the components, the dry friction coefficient of the high-temperature resistant friction material at 350 °C is controlled between 0.4 and 0.45. It not only has a high friction coefficient, but also a stable friction coefficient. At the same time, it also has the characteristics of low wear rate and good impact strength. Thus, the high-temperature resistant friction material is suitable for use in industrial brakes used in high-temperature and high-pressure environments.

[0023] Furthermore, the present invention provides a preparation method for the high-temperature resistant friction material. It is formed by hot pressing and cured by a two-stage heating method, which not only saves energy consumption, but also makes the performance of the high-temperature resistant friction material more stable. Specific embodiments

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 making creative efforts belong to the scope of protection of the present invention.

[0025] The present invention provides a high-temperature resistant friction material, which comprises the following components in parts by weight: 18-20 parts of modified phenolic resin, 3-4 parts of nitrile rubber, 2-3 parts of bauxite powder, 10-12 parts of barium sulfate, 1-2 parts of iron oxide red, 3-5 parts of iron oxide black, 36-41 parts of sepiolite wool, 12-16 parts of glass fiber, 2-3 parts of tire powder and 3-5 parts of flake graphite.

[0026] The high-temperature resistant friction material provided by the present invention, by weight, comprises 18-20 parts of modified phenolic resin, preferably 19 parts. In the present invention, the particle size of the modified phenolic resin is preferably ≥200 mesh. Cashew shell oil is a natural product, a viscous liquid extracted from mature cashew shells. Using it to modify phenolic resin can significantly improve the toughness. The modified phenolic resin used in the friction material has a soft and tough friction performance, is not easy to fall off, makes the composition and heat-receiving state on the surface of the friction material uniform, and ensures stable friction performance.

[0027] In the embodiments of the present invention, the modified phenolic resin is purchased from Wuhan Foster Technology Co., Ltd., 6601 resin.

[0028] The high-temperature resistant friction material provided by the present invention, by weight, comprises 3-4 parts of nitrile rubber, preferably 3.4 parts. In the present invention, the particle size of the nitrile rubber is preferably ≥300 mesh, and the acrylonitrile content in the nitrile rubber is preferably 30-35 wt%.

[0029] In the present invention, the modified phenolic resin and nitrile rubber can bond the components and act as binders. Among them, the modified phenolic resin has good adhesiveness, a curing temperature of 150-170 °C, and a thermal decomposition temperature of about 310 °C. The lower curing temperature and viscosity are beneficial to reducing the preparation difficulty, facilitating the hot pressing and curing of the material blocks, and reducing the hardness and modulus. The nitrile rubber has poor viscosity at low temperatures but has high heat resistance and can compensate for the influence brought by the thermal decomposition of the resin at high temperatures. The two cooperate synergistically to fully exert the bonding effect. At the same time, the use of rubber can reduce braking noise and increase the friction coefficient.

[0030] The high-temperature resistant friction material provided by the present invention, by weight, comprises 2-3 parts of bauxite powder, preferably 2.3 parts. In the present invention, the particle size of the bauxite powder is preferably ≥500 mesh. In the present invention, the content of bauxite in the bauxite powder is preferably ≥95 wt%.

[0031] The high-temperature resistant friction material provided by the present invention, by weight, comprises 10-12 parts of barium sulfate, preferably 10.8 parts. In the present invention, the particle size of the barium sulfate is preferably ≥500 mesh. In the present invention, the purity of the barium sulfate is preferably ≥95%.

[0032] The high-temperature resistant friction material provided by the present invention, by weight, comprises 1-2 parts of iron oxide red, preferably 1.5 parts. In the present invention, the particle size of the iron oxide red is preferably ≥500 mesh. In the present invention, the purity of the iron oxide red is preferably ≥95 wt%.

[0033] The high-temperature resistant friction material provided by the present invention, by weight, comprises 3-5 parts of iron oxide black, preferably 4 parts. In the present invention, the particle size of the iron oxide black is preferably ≥500 mesh. In the present invention, the purity of the iron oxide black is preferably ≥95 wt%.

[0034] In the present invention, the bauxite powder, barium sulfate, iron oxide red and iron oxide black are used as abrasion-increasing fillers, which can make the friction material have good friction coefficients. Among them, the bauxite powder is the material with the strongest abrasion-increasing effect and has a strong abrasion-increasing effect at both normal and high temperatures; barium sulfate can form a stable friction layer boundary at high temperatures, which can reduce wear and stabilize the coefficient; iron oxide red and iron oxide black play the role of increasing the normal temperature coefficient and adjusting the color of the friction plate. It can be understood that each component synergistically exerts a stable friction coefficient under the limited dosage.

[0035] The high-temperature resistant friction material provided by the present invention, by weight, comprises 36-41 parts of sepiolite wool, preferably 38.5 parts. In the present invention, the fiber length of the sepiolite wool is preferably ≤3 mm.

[0036] The high-temperature resistant friction material provided by the present invention, by weight, comprises 12 to 16 parts of glass fiber, preferably 14 parts. In the present invention, the length of the glass fiber is preferably 2 to 3 mm.

[0037] In the present invention, the sepiolite wool and the glass fiber serve as reinforcing fibers, which can endow the friction material with sufficient mechanical properties. Among them, the sepiolite wool has good adsorption and dispersibility, and can be evenly distributed among the fillers during mixing and stirring, playing a good connecting role. The glass fiber is used for the impact strength and hardness of the friction material product.

[0038] The high-temperature resistant friction material provided by the present invention, by weight, comprises 2 to 3 parts of tire powder, preferably 2.5 parts. In the present invention, the particle size of the tire powder is preferably 20 to 40 mesh.

[0039] The high-temperature resistant friction material provided by the present invention, by weight, comprises 3 to 5 parts of flake graphite, preferably 4 parts. In the present invention, the particle size of the flake graphite is preferably ≥30 mesh.

[0040] In the present invention, the tire powder and the flake graphite serve as regulators, which can reduce wear, hardness, noise and regulate the friction coefficient. The tire powder can effectively reduce the hardness of the product and reduce braking noise; the flake graphite can reduce wear, stabilize the friction coefficient and has good high-temperature resistance.

[0041] In the present invention, the dry friction coefficient of the high-temperature resistant friction material at 350 °C is preferably 0.4 to 0.45; the impact strength is preferably 4.9 to 5.3 kJ / m 2 ; the hardness is preferably HRS90 to 95.

[0042] In the present invention, the high-temperature resistant friction material is applied to an industrial brake that is under high temperature and high pressure conditions for a long time and is often in a braking state. It not only needs to have a relatively high dry friction coefficient (dry friction: friction in the atmosphere) to achieve a rapid braking effect, but also, in order to ensure the smoothness of the braking process and reduce vibration and noise, the friction coefficient needs to be stable in a high-temperature environment. At the same time, it also needs to have a low wear rate and good impact strength. The high-temperature resistant friction material provided by the present invention uses modified phenolic resin and nitrile rubber as adhesives to bond other components together, making it have sufficient ductility and impact strength. The combination of modified phenolic resin and nitrile rubber optimizes the bonding performance and reduces the preparation difficulty. Bauxite powder, barium sulfate, iron oxide red, and iron oxide black are combined to form a stable friction coefficient and have a low wear rate. Sepiolite wool has good adsorption and dispersibility and can be evenly distributed among the fillers during mixing and stirring, playing a good connecting role. Glass fiber is used for the impact strength and hardness of the friction material product. Tire powder can effectively reduce the hardness of the product and reduce braking noise; flake graphite can reduce wear, stabilize the friction coefficient, and has good high-temperature resistance. It can be understood that the present invention controls the components and addition amounts of the high-temperature resistant friction material, and through the combined action of each component, the friction material has a high-temperature resistant and stable dry friction coefficient, as well as a low wear rate and good impact strength.

[0043] The present invention has no special limitation on the specific sources of the nitrile rubber, bauxite powder, barium sulfate, iron oxide red, iron oxide black, sepiolite wool, glass fiber, tire powder, and flake graphite, and conventional commercially available products in the art can be used.

[0044] The present invention provides a preparation method for the high-temperature resistant friction material described in any one of the above, including the following steps:

[0045] 1) Mix modified phenolic resin, nitrile rubber, bauxite powder, barium sulfate, iron oxide red, iron oxide red, sepiolite wool, glass fiber, tire powder, and flake graphite to obtain a mixed material;

[0046] 2) Hot press the mixed material to obtain a semi-finished product;

[0047] 3) Cure the semi-finished product to obtain a high-temperature resistant friction material.

[0048] The present invention mixes modified phenolic resin, nitrile rubber, bauxite powder, barium sulfate, iron oxide red, iron oxide red, sepiolite wool, glass fiber, tire powder, and flake graphite to obtain a mixed material. In the present invention, the mixing method is preferably stirring. The stirring time is preferably 5 - 15 min, more preferably 10 min. The stirring speed is preferably 1400 - 1600 r / min, more preferably 1500 r / min.

[0049] After obtaining the mixed material, the present invention hot-presses and forms the mixed material to obtain a semi-finished product. In the present invention, the hot-pressing temperature during hot-pressing and forming is preferably 155 - 165 °C, the pressure is preferably 28 - 32 Mpa, and the holding time is preferably calculated at 1 mm / min of the forming thickness.

[0050] After obtaining the semi-finished product, the present invention cures the semi-finished product to obtain a high-temperature resistant friction material. In the present invention, a two-stage heating method is preferably adopted for the curing treatment. First, it is heated from room temperature to 135 - 145 °C in 0.8 - 1.2 h and held at 135 - 145 °C for 1.8 - 2.2 h; then it is heated from 135 - 145 °C to 165 - 175 °C in 0.8 - 1.2 h and held at 165 - 175 °C for 8 - 10 h. In the present invention, due to the differences in specific heat and expansion coefficient of each component material, slow heating is adopted during the heating stage, and slow heating can reduce the damage to the product caused by these differences. Holding at 135 - 145 °C is to remove the moisture in the product, and heating to 165 - 175 °C and holding is to completely melt the resin and be fully absorbed by the remaining materials, and finally tightly combine into a whole.

[0051] The present invention provides the application of the high-temperature resistant friction material described in any one of the above in an industrial brake.

[0052] In order to further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below in conjunction with embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0053] The specific sources of each component in the embodiments are as follows:

[0054] The modified phenolic resin is 6601 resin from Hanfoster Technology Co., Ltd.; the nitrile rubber is N-1S powdered nitrile rubber from Nanjing Xinfeima Chemical Co., Ltd.; the bauxite powder is from Gongyi Kaiyuan Superfine Powder Co., Ltd.; the barium sulfate is from Zhushan Qinba Barium Salt Co., Ltd.; the iron oxide red and iron oxide black are purchased from Tianjin Branch of Yixing Huayi Yipin Coloring Technology Co., Ltd.; the sepiolite wool is WK-A from Xixia Wanli Mineral Products Development Co., Ltd.; the glass fiber is EC13-03 from Danyang Zhenxing Glass Fiber Co., Ltd.; the tire powder is from Jincheng Shuntaihe Industry and Trade Co., Ltd.; the flake graphite is from Qingdao Jintao Graphite New Material Co., Ltd.

[0055] Example 1

[0056] By weight, the formula of the high-temperature resistant friction material is: 19 parts of modified phenolic resin, 3.4 parts of nitrile rubber, 2.3 parts of bauxite powder, 10.8 parts of barium sulfate, 1.5 parts of iron oxide red, 4 parts of iron oxide black, 38.5 parts of sepiolite wool, 14 parts of glass fiber, 2.5 parts of tire powder, and 4 parts of flake graphite.

[0057] Among them: the particle size of the modified phenolic resin is 200 mesh; the particle size of the nitrile rubber is 300 mesh; the particle size of the bauxite powder is 500 mesh; the particle size of the barium sulfate is 500 mesh; the particle size of the iron oxide red is 500 mesh; the particle size of the iron oxide black is 500 mesh; the fiber length of the sepiolite wool is 2.8 mm; the fiber length in the glass fiber is 2 - 3 mm; the particle size of the tire powder is 20 - 40 mesh; the particle size of the flake graphite is 30 mesh.

[0058] (1) Weigh each component material according to the above formula, and put the weighed materials into a high-speed mixer and mix them at a speed of 1500 r / min for 10 minutes.

[0059] (2) Hot pressing and forming: Put the obtained mixed material into a mold for hot pressing. The mold temperature is 160 °C, the pressure is 30 MPa, and the pressure holding time is calculated at 1 mm / min according to the forming thickness to obtain a semi-finished block.

[0060] (3) Put the semi-finished block obtained by hot pressing and forming in step (2) into an oven for curing. First, heat it from room temperature to 140 °C in 1 h and keep it at 140 °C for 2 h; then heat it from 140 °C to 170 °C in 1 h and keep it at 170 °C for 9 h to obtain a high-temperature resistant friction material.

[0061] Example 2

[0062] By weight, the formula of the high-temperature resistant friction material is: 18 parts of modified phenolic resin, 4 parts of nitrile rubber, 2 parts of bauxite powder, 12 parts of barium sulfate, 1 part of iron oxide red, 5 parts of iron oxide black, 36 parts of sepiolite wool, 16 parts of glass fiber, 2 parts of tire powder, and 5 parts of flake graphite.

[0063] Among them: the particle size of the modified phenolic resin is 200 mesh; the particle size of the nitrile rubber is 300 mesh; the particle size of the bauxite powder is 500 mesh; the particle size of the barium sulfate is 500 mesh; the particle size of the iron oxide red is 500 mesh; the particle size of the iron oxide black is 500 mesh; the fiber length of the sepiolite wool is 2.8 mm; the fiber length in the glass fiber is 2 - 3 mm; the particle size of the tire powder is 20 - 40 mesh; the particle size of the flake graphite is 30 mesh.

[0064] (1) Weigh each component material according to the above formula, and put the weighed materials into a high-speed mixer and mix them at a speed of 1500 r / min for 10 minutes.

[0065] (2) Hot pressing and forming: Put the obtained mixed material into a mold for hot pressing. The mold temperature is 155 °C, the pressure is 32 MPa, and the pressure holding time is calculated at 1 mm / min according to the forming thickness to obtain a semi-finished block.

[0066] (3) Put the semi-finished material blocks formed by hot pressing in step (2) into an oven for curing. First, heat from room temperature to 135 °C in 0.8 h and keep warm at 135 °C for 2.2 h; then heat from 135 °C to 175 °C in 1.2 h and keep warm at 175 °C for 8 h to obtain the high-temperature resistant friction material.

[0067] Example 3

[0068] By weight, the formula of the high-temperature resistant friction material is: 20 parts of modified phenolic resin, 3 parts of nitrile rubber, 3 parts of bauxite powder, 10 parts of barium sulfate, 2 parts of iron oxide red, 3 parts of iron oxide black, 41 parts of sepiolite wool, 12 parts of glass fiber, 3 parts of tire powder, and 3 parts of flake graphite.

[0069] Among them: the particle size of the modified phenolic resin is 200 mesh; the particle size of the nitrile rubber is 300 mesh; the particle size of the bauxite powder is 500 mesh; the particle size of the barium sulfate is 500 mesh; the particle size of the iron oxide red is 500 mesh; the particle size of the iron oxide black is 500 mesh; the fiber length of the sepiolite wool is 2.8 mm; the fiber length in the glass fiber is 2 - 3 mm; the particle size of the tire powder is 20 - 40 mesh; the particle size of the flake graphite is 30 mesh.

[0070] (1) Weigh each component material according to the above formula, and put the weighed materials into a high-speed mixer and mix at a speed of 1500 r / min for 10 minutes.

[0071] (2) Hot pressing and forming: Put the obtained mixed material into a mold for hot pressing. The mold temperature is 165 °C, the pressure is 28 MPa, and the pressure holding time is calculated as 1 mm / min according to the forming thickness to obtain semi-finished material blocks.

[0072] (3) Put the semi-finished material blocks formed by hot pressing in step (2) into an oven for curing. First, heat from room temperature to 145 °C in 1.2 h and keep warm at 145 °C for 1.8 h; then heat from 145 °C to 165 °C in 0.8 h and keep warm at 165 °C for 10 h to obtain the high-temperature resistant friction material.

[0073] Comparative Example 1

[0074] The preparation method is the same as that of Example 1, the difference is that the content of the modified phenolic resin is 22.4 parts, and the nitrile rubber is not added.

[0075] The specific formula is: 22.4 parts of modified phenolic resin, 2.3 parts of bauxite powder, 10.8 parts of barium sulfate, 1.5 parts of iron oxide red, 4 parts of iron oxide black, 38.5 parts of sepiolite wool, 14 parts of glass fiber, 2.5 parts of tire powder, and 4 parts of flake graphite.

[0076] Comparative Example 2

[0077] The preparation method is the same as that of Example 1, except that the content of the modified phenolic resin is 15 parts and the content of the nitrile rubber is 7 parts.

[0078] The specific formulation is: 15 parts of modified phenolic resin, 7 parts of nitrile rubber, 2.3 parts of bauxite powder, 10.8 parts of barium sulfate, 1.5 parts of iron oxide red, 4 parts of iron oxide black, 38.5 parts of sepiolite wool, 14 parts of glass fiber, 2.5 parts of tire powder, and 4 parts of flake graphite.

[0079] Comparative Example 3

[0080] The preparation method is the same as that of Example 1, except that the content of the modified phenolic resin is 22 parts and the content of the nitrile rubber is 1 part.

[0081] The specific formulation is: 22 parts of modified phenolic resin, 1 part of nitrile rubber, 2.3 parts of bauxite powder, 10.8 parts of barium sulfate, 1.5 parts of iron oxide red, 4 parts of iron oxide black, 38.5 parts of sepiolite wool, 14 parts of glass fiber, 2.5 parts of tire powder, and 4 parts of flake graphite.

[0082] Comparative Example 4

[0083] The preparation method is the same as that of Example 1, except that the amount of barium sulfate used is 16 parts and the amount of bauxite powder used is 1 part.

[0084] The specific formulation is: 19 parts of modified phenolic resin, 3.4 parts of nitrile rubber, 1 part of bauxite powder, 16 parts of barium sulfate, 1.5 parts of iron oxide red, 4 parts of iron oxide black, 38.5 parts of sepiolite wool, 14 parts of glass fiber, 2.5 parts of tire powder, and 4 parts of flake graphite.

[0085] Comparative Example 5

[0086] The preparation method is the same as that of Example 1, except that the amount of sepiolite wool used is 32.5 parts and the amount of glass fiber used is 20 parts.

[0087] The specific formulation is: 19 parts of modified phenolic resin, 3.4 parts of nitrile rubber, 2.3 parts of bauxite powder, 10.8 parts of barium sulfate, 1.5 parts of iron oxide red, 4 parts of iron oxide black, 32.5 parts of sepiolite wool, 20 parts of glass fiber, 2.5 parts of tire powder, and 4 parts of flake graphite.

[0088] Comparative Example 6

[0089] The preparation method is the same as that of Example 1, except that flake graphite is not added.

[0090] The specific formulation is: 19 parts of modified phenolic resin, 3.4 parts of nitrile rubber, 2.3 parts of bauxite powder, 10.8 parts of barium sulfate, 1.5 parts of iron oxide red, 4 parts of iron oxide black, 38.5 parts of sepiolite wool, 14 parts of glass fiber, 2.5 parts of tire powder.

[0091] Comparative Example 7

[0092] Except for the different hot pressing forming processes in step (3) of the preparation method, other operating steps are exactly the same as those in Example 1. The specific preparation method is as follows:

[0093] (1) Weigh each component material according to the above formula, and put the weighed materials into a high-speed mixer and mix them at a speed of 1500 r / min for 10 minutes.

[0094] (2) Hot pressing forming: Put the obtained mixed material into a mold for hot pressing. The mold temperature is 160 °C, the pressure is 30 MPa, and the pressure holding time is calculated at 1 mm / min according to the forming thickness to obtain a semi-finished material block.

[0095] (3) Put the semi-finished material block obtained by hot pressing forming in step (2) into an oven for curing. Heat it from room temperature to 170 °C in 1 h and keep it at 170 °C for 10 h to obtain a high-temperature resistant friction material.

[0096] Performance Test

[0097] The dry friction coefficients of the high-temperature resistant friction materials prepared in Examples 1 to 3 and Comparative Examples 1 to 7 were tested respectively. Each material was tested twice at the same temperature. The specific results are shown in Table 1.

[0098] Table 1 Performance Test Results

[0099]

[0100] Note: The process of testing the dry friction coefficient in Table 1 above is as follows: During the heating process, tests are carried out at 100 °C, 150 °C, 200 °C, 250 °C, 300 °C, and 350 °C in sequence. After reaching 350 °C, cooling is carried out, and during the cooling process, tests are carried out at 300 °C, 250 °C, 200 °C, 150 °C, and 100 °C in sequence. Among them, " ← " in Table 1 indicates the start of cooling and the start of testing during the cooling process.

[0101] The wear rates, impact strengths, and hardnesses of the high-temperature resistant friction materials prepared in Examples 1 to 3 and Comparative Examples 1 to 7 were tested respectively. The specific results are shown in Table 2.

[0102] Among them, the friction coefficient test was determined according to GB 5763-2008, 6.3 Friction Performance Test. The wear rate test was determined according to GB 5763-2008, 6.3 Friction Performance Test. The impact strength test was determined according to GB / T33835-2017 Test Method for Impact Strength of Friction Materials. The hardness test was determined according to GB / T 5766-2023 Rockwell Hardness Test Method for Friction Materials.

[0103] Table 2

[0104]

[0105]

[0106] From the comprehensive Table 1 and Table 2, it can be concluded that the friction coefficient, hardness and impact strength of the high-temperature resistant friction material prepared in the embodiments of the present invention can all meet the design indicators. Among them, the product of Embodiment 1 best meets the design indicators and has good processability. Compared with Embodiment 1, although the friction coefficients of Embodiments 2 and 3 can reach the required values, vibration and noise are likely to occur during actual use, and the wear rate of Embodiment 3 is relatively high; the friction coefficients of Comparative Examples 1-5 are lower than 0.4 at some temperatures; although the friction coefficient of Comparative Example 6 meets the requirement between 0.4 and 0.45, the fluctuation of the recovery coefficient is relatively large after cooling, and the wear rate is too high and the noise is large; for Comparative Example 7, because the temperature rises too fast during curing, the product is bent and uneven.

[0107] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A high temperature resistant friction material, characterized in that: The invention comprises the following components in parts by weight: 18 to 20 parts of modified phenolic resin, 3 to 4 parts of nitrile rubber, 2 to 3 parts of alumina powder, 10 to 12 parts of barium sulfate, 1 to 2 parts of red iron oxide, 3 to 5 parts of black iron oxide, 36 to 41 parts of sepiolite wool, 12 to 16 parts of glass fiber, 2 to 3 parts of tire powder and 3 to 5 parts of flake graphite; The modified phenolic resin is cashew nut shell oil modified phenolic resin.

2. The high temperature resistant friction material according to claim 1, characterized in that: The particle size of the nitrile rubber is ≥300 meshes, and the acrylonitrile content in the nitrile rubber is 30-35wt%.

3. The high temperature resistant friction material according to claim 1, characterized in that: The particle size of the modified phenolic resin is ≥200 meshes; the particle size of the tire powder is 20-40 meshes, the particle size of the flake graphite is ≥30 meshes; the particle sizes of the alumina powder, barium sulfate, red iron oxide and black iron oxide are all ≥500 meshes.

4. The high temperature resistant friction material according to claim 1, characterized in that: The fiber length of the sepiolite is ≤3 mm; the length of the glass fiber is 2 to 3 mm.

5. The high temperature resistant friction material according to claim 1, characterized in that: The high temperature resistant friction material has a dry friction coefficient of 0.40 to 0.45 at 350°C and an impact strength of 4.9 to 5.3 dJ / cm 2 ; Hardness is HRS90~95.

6. The method for preparing a high temperature resistant friction material according to any one of claims 1 to 5, characterized in that: The steps include: 1) mixing modified phenolic resin, nitrile rubber, alumina powder, barium sulfate, red iron oxide, red iron oxide, sepiolite wool, glass fiber, tire powder and flake graphite to obtain a mixed material; 2) hot pressing the mixed material to obtain a semi-finished product; 3) Curing the semi-finished product to obtain a high temperature resistant friction material.

7. The preparation method according to claim 6, characterized in that: The hot pressing temperature during hot pressing molding in step 2) is 155-165° C., the pressure is 28-32 MPa, and the holding time is calculated based on the molding thickness of 1 mm / min.

8. The preparation method according to claim 6, characterized in that: In step 3), a two-stage heating method is used for curing treatment, firstly, the temperature is raised from room temperature to 135-145°C for 0.8-1.2 hours, and then kept at 135-145°C for 1.8-2.2 hours; then, the temperature is raised from 135-145°C to 165-175°C for 0.8-1.2 hours, and then kept at 165-175°C for 8-10 hours.

9. Use of the high temperature resistant friction material according to any one of claims 1 to 5 in industrial brakes.

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