Preparation method of graphene reinforced composite material brake pad

Abstract

The invention provides a preparation method of a graphene reinforced composite material brake pad, and belongs to the field of friction materials. The brake pad adopts graphene as a reinforcing agent, so that the high temperature resistance and the thermal conductivity are improved; meanwhile, nano aluminum oxide and nano silicon carbide are added, so that the mechanical property of the friction material is enhanced. A hot pressing sintering process is adopted, so that the material is densified, and the wear resistance is improved. The brake pad has high wear resistance, high thermal conductivity, stable friction coefficient and excellent high-temperature heat resistance, and is suitable for a high-performance brake system.

Description

Technical Field

[0001] The present invention relates to the field of friction materials, and in particular to a preparation method of a graphene-reinforced composite brake pad. Background Art

[0002] As a key safety component in the braking systems of automobiles, trains, motorcycles, and industrial applications, the performance of brake pads directly affects the braking effect and safety of vehicles. Currently, brake pads on the market are mainly divided into three categories: metal-based brake pads (semi-metallic, low-metallic), ceramic-based brake pads, and resin-based brake pads (non-metallic organic brake pads). Different types of brake pads have their own advantages and disadvantages in terms of performance, cost, and applicable environments.

[0003] Main problems of existing brake pads: Metal-based brake pads (such as semi-metallic brake pads) are widely used in high-load working conditions due to their high strength and good heat dissipation. However, they have the following disadvantages: they are prone to oxidation under high-temperature conditions, resulting in performance degradation; they have a relatively high hardness, causing significant wear to the brake disc and affecting the service life of the braking system; they may produce noise or rust problems in low-temperature or humid environments. Ceramic-based brake pads are mainly used in high-end automobiles and racing cars, with excellent high-temperature resistance and low dust generation. However, they have the following problems: high manufacturing costs, making it difficult to be widely promoted to ordinary vehicles on a large scale; there is a risk of material fragmentation under extreme working conditions (such as long-term intense braking). Resin-based brake pads are made with phenolic resin as the matrix, adding various fillers and reinforcing materials, and have the advantages of low noise and low dust, and are widely used in passenger cars and commercial vehicles. However, their disadvantages include: poor heat dissipation, prone to friction coefficient attenuation (thermal fade) in high-temperature environments; low wear resistance and short service life; being greatly affected by the environment, such as a possible performance decline when the humidity is high. Therefore, there is still room for improvement in the high-temperature stability, friction performance, wear resistance, etc. of existing brake pads. Especially under high-speed and high-load working conditions, it is difficult for traditional brake pads to achieve both excellent friction performance and wear resistance.

[0004] In recent years, the introduction of new nanomaterials has provided a new direction for improving the performance of brake pads. Among them, graphene has shown great potential in the field of friction materials due to its extremely high thermal conductivity, mechanical strength, and high-temperature resistance. Research shows that an appropriate amount of graphene can: improve thermal conductivity, accelerate the dissipation of braking heat, and reduce the problem of thermal fade; enhance material strength, improve the wear resistance and impact resistance of the matrix; optimize friction performance, and maintain a stable friction coefficient under high-temperature and high-speed braking conditions.

[0005] Although the application of graphene in brake pads has great potential, there are still the following technical difficulties: the dispersion problem of graphene: Graphene is prone to agglomeration, resulting in uneven distribution in the composite material, which will ultimately affect the high-temperature resistance of the brake pad, showing an obvious thermal fade phenomenon and unstable friction performance; poor wear resistance, affecting the service life of the brake pad. Summary of the invention

[0006] In order to overcome at least one of the technical problems in the above background technology, the present invention proposes a method for preparing a graphene-enhanced composite brake pad, which overcomes the shortcomings of the existing brake pads through the following technical solutions:

[0007] A method for preparing a graphene-reinforced composite brake pad, characterized in that the preparation is carried out by the following steps:

[0008] (1) Ingredients: weigh each component according to the ratio of raw materials;

[0009] (2) Mixing: adding graphene, nano-alumina, nano-silicon carbide, fiber reinforcement, filler, phenolic resin matrix, curing agent, lubricant, silane coupling agent and brake pad synergistic agent into a high-speed mixer, mixing at 500-1500 rpm for 30-120 min, or wet mixing at 300-800 rpm for 1-4 h using a planetary ball mill;

[0010] (3) Preforming: The mixed material is placed in a mold and cold pressed at a pressure of 5-20 MPa, a molding temperature of 25-80°C, and a holding time of 30-300 s;

[0011] (4) Hot pressing sintering: sintering at 150-250°C and 10-50 MPa for 1-3 h, with a heating rate of 2-10°C / min, to densify the composite material and improve its mechanical properties and wear resistance;

[0012] (5) Post-processing and testing: The finished products are trimmed to size, tested for hardness, friction coefficient, wear resistance and other indicators, and packaged for storage.

[0013] As a preferred embodiment of the preparation method of the present invention, the ratio of the raw materials is calculated by mass:

[0014] Graphene: 0.5-5 parts;

[0015] Nano-alumina: 2-10 parts;

[0016] Nano silicon carbide: 3-12 parts;

[0017] Fiber reinforcement material: 5-20 parts;

[0018] Phenolic resin matrix: 20-40 parts;

[0019] Filler: 10-30 parts;

[0020] Curing agent: 3-10 parts;

[0021] Lubricant: 0.5-5 parts;

[0022] Silane coupling agent: 0.1 - 1 part;

[0023] Brake pad synergistic additive: 0.2 - 2 parts.

[0024] As a preferred embodiment of the preparation method of the present invention, the graphene is monolayer or few-layer graphene, with a sheet diameter of 0.5 - 5 μm and a thickness ≤ 10 nm.

[0025] As a preferred embodiment of the preparation method of the present invention, the fiber reinforcement material includes at least one of glass fiber, aramid fiber, and basalt fiber.

[0026] As a preferred embodiment of the preparation method of the present invention, the filler includes at least one of barium sulfate, wollastonite, expanded graphite, and mica powder.

[0027] As a preferred embodiment of the preparation method of the present invention, the curing agent includes at least one of hexamethylenetetramine and benzenesulfonyl chloride.

[0028] As a preferred embodiment of the preparation method of the present invention, the lubricant includes at least one of graphite and MoS₂.

[0029] As a preferred embodiment of the preparation method of the present invention, the silane coupling agent includes at least one of γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-glycidoxypropyltrimethoxysilane.

[0030] As a preferred embodiment of the preparation method of the present invention, the preparation method of the brake pad synergistic additive:

[0031] Thiol ring-opening: Take 100 parts of 2-[(thiophen-2-ylmethoxy)methyl]oxirane, add 120 - 150 parts of ethanolamine mercaptoacetate to the reaction vessel, add 5 - 10 parts of sodium hydroxide as a catalyst, and react at 40°C - 60°C for 2 - 4 hours;

[0032] Selenyl addition: Add 100 - 120 parts of allylphenylselenium and 1 - 3 parts of AIBN to the above system, initiate double bond addition at 60°C - 80°C, and react for 3 - 5 hours to obtain the brake pad synergistic additive.

[0033] Technical effects:

[0034] 1) Improve thermal conductivity and reduce heat fade phenomenon:

[0035] The high thermal conductivity of graphene enables the heat generated by friction of the brake pad to be transferred to the surface and dissipated faster, thereby reducing the local high-temperature accumulation and lowering the problem of the friction coefficient decrease (heat fade) caused by temperature rise, and improving the braking stability under high-temperature conditions.

[0036] The sulfur - ether bonds formed in the synergistic additive have a relatively high bond energy, which can effectively enhance the high - temperature resistance of the brake pads, enabling them to maintain good performance stability in high - temperature environments and reducing performance degradation caused by high temperatures.

[0037] 2) Enhance wear resistance and extend the service life of brake pads: The high hardness of nano - alumina and nano - silicon carbide can effectively enhance the wear resistance of the matrix, reduce the wear rate of materials during braking, thereby extending the service life of the brake pads. At the same time, it reduces dust generation and damage to the brake disc.

[0038] 3) Stable friction performance: The selenium group in allyl phenyl selenide can effectively adjust the friction interface, making the friction coefficient more stable, avoiding large fluctuations in the friction coefficient, and improving the braking performance and safety of the brake pads. Specific implementation mode

[0039] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made. These all belong to the protection scope of the present invention.

[0040] The reagents used in the embodiments and comparative examples of the present invention are all commercially available, but are not limited to these materials.

[0041] Example 1

[0042] Raw material composition:

[0043] Graphene: 1.0 kg

[0044] Nano - alumina: 5.0 kg

[0045] Nano - silicon carbide: 6.0 kg

[0046] Glass fiber: 10.0 kg

[0047] Phenolic resin matrix: 30.0 kg

[0048] Filler (wollastonite + mica powder = 1:1): 20.0 kg

[0049] Curing agent (hexamethylenetetramine): 5.0 kg

[0050] Lubricant (graphite + MoS2 = 1:1): 2.0 kg

[0051] Silane coupling agent (γ - aminopropyltriethoxysilane): 0.5 kg

[0052] Brake pad synergistic additive: 0.5 kg

[0053] Preparation method of brake pad efficiency enhancer: Mercapto ring opening: Take 1000 g of 2-[(thiophen-2-ylmethoxy)methyl]oxirane, add 1200 g of ethanolamine mercaptoacetate to the reaction vessel, add 50 g of sodium hydroxide as a catalyst, and react at 40 °C for 4 hours; Seleno addition: Add 1000 g of allylphenylselenium and 10 g of AIBN to the above system, initiate double bond addition at 60 °C, and react for 5 hours to obtain the brake pad efficiency enhancer.

[0054] Preparation steps:

[0055] 1. Mixing: Add the above raw materials to a high-speed mixer and stir at 1000 rpm for 60 min;

[0056] 2. Pre-forming: Cold press the mixture into a shape at a pressure of 10 MPa, a temperature of 60 °C, and a pressure holding time of 150 s;

[0057] 3. Hot press sintering: Heating rate 5 °C / min, temperature 200 °C, pressure 30 MPa, heat preservation 2 h;

[0058] 4. Post-treatment: Perform size trimming and friction performance testing.

[0059] Example 2

[0060] Raw material composition:

[0061] Graphene: 2.5 kg

[0062] Nano-aluminum oxide: 7.0 kg

[0063] Nano-silicon carbide: 10.0 kg

[0064] Aramid fiber: 15.0 kg

[0065] Phenolic resin matrix: 35.0 kg

[0066] Filler (expanded graphite): 25.0 kg

[0067] Curing agent (benzenesulfonyl chloride): 6.0 kg

[0068] Lubricant (MoS2): 3.0 kg

[0069] Silane coupling agent (γ-methacryloxypropyltrimethoxysilane): 0.7 kg

[0070] Brake pad efficiency enhancer: 1.0 kg

[0071] Preparation method of brake pad efficiency enhancer: Thiol ring-opening: Take 1000 g of 2-[(thiophen-2-ylmethoxy)methyl]oxirane and add 1300 g of ethanolamine thioglycolate to the reaction vessel. Add 65 g of sodium hydroxide as a catalyst and react at 50 °C for 3 hours; Selenene addition: Add 1100 g of allylphenylselenium and 20 g of AIBN to the above system, and initiate double bond addition at 70 °C for 4 hours to obtain the brake pad efficiency enhancer.

[0072] Preparation steps:

[0073] 1. Mixing: The raw materials are wet-mixed with a planetary ball mill at a rotational speed of 400 rpm for 3 h;

[0074] 2. Pre-forming: Pressure 15 MPa, temperature 40 °C, holding pressure time 180 s;

[0075] 3. Hot pressing and sintering: Heating rate 6 °C / min, sintering temperature 220 °C, pressure 40 MPa, time 2.5 h;

[0076] 4. Post-treatment and testing: After polishing, test the friction coefficient and wear resistance.

[0077] Example 3

[0078] Raw material composition:

[0079] Graphene: 0.8 kg

[0080] Nano-aluminum oxide: 3.0 kg

[0081] Nano-silicon carbide: 4.5 kg

[0082] Basalt fiber: 8.0 kg

[0083] Phenolic resin matrix: 25.0 kg

[0084] Filler (barium sulfate + mica powder = 2:1): 15.0 kg

[0085] Curing agent (hexamethylenetetramine): 4.0 kg

[0086] Lubricant (graphite): 1.0 kg

[0087] Silane coupling agent (γ-glycidoxypropyltrimethoxysilane): 0.3 kg

[0088] Brake pad efficiency enhancer: 1.5 kg

[0089] Preparation method of brake pad efficiency enhancer: Thiol ring-opening: Take 1000 g of 2-[(thiophen-2-ylmethoxy)methyl]oxirane and add 1400 g of ethanolamine mercaptoacetate to the reaction vessel. Add 80 g of sodium hydroxide as a catalyst and react at 50 °C for 3 hours; Selenene addition: Add 1100 g of allylphenylselenium and 20 g of AIBN to the above system, and initiate double bond addition at 70 °C for 4 hours to obtain the brake pad efficiency enhancer.

[0090] Preparation steps:

[0091] 1. Mixing: Mix in a high-speed mixer at a rotation speed of 750 rpm for 90 min;

[0092] 2. Pre-forming: Pressure 12 MPa, forming temperature 50 °C, pressure holding time 200 s;

[0093] 3. Hot pressing and sintering: Heating rate 4 °C / min, sintering temperature 180 °C, pressure 20 MPa, heat preservation 2 h;

[0094] 4. Post-treatment and testing: Inspect hardness and friction and wear performance.

[0095] Example 4

[0096] Raw material composition:

[0097] Graphene: 4.0 kg

[0098] Nano-aluminum oxide: 9.0 kg

[0099] Nano-silicon carbide: 11.0 kg

[0100] Aramid fiber + glass fiber mixture (1:1): 18.0 kg

[0101] Phenolic resin matrix: 38.0 kg

[0102] Filler (expanded graphite + mica powder = 3:2): 28.0 kg

[0103] Curing agent (benzenesulfonyl chloride): 8.0 kg

[0104] Lubricant (graphite + MoS2 = 2:1): 4.0 kg

[0105] Silane coupling agent (γ-aminopropyltriethoxysilane): 1.0 kg

[0106] Brake pad efficiency enhancer: 2.0 kg

[0107] Preparation method of brake pad efficiency enhancer: Thiol ring-opening: Take 1000 g of 2-[(thiophen-2-ylmethoxy)methyl]oxirane and add 1500 g of ethanolamine thioglycolate to the reaction vessel. Add 100 g of sodium hydroxide as a catalyst and react at 60 °C for 2 hours; Selenene addition: Add 1200 g of allylphenylselenium and 30 g of AIBN to the above system, and initiate double bond addition at 80 °C for 3 hours to obtain the brake pad efficiency enhancer.

[0108] Preparation steps:

[0109] 1. Mixing: Wet mixing in a planetary ball mill at a rotation speed of 600 rpm for 4 h;

[0110] 2. Pre-forming: Pressure of 18 MPa, forming temperature of 70 °C, and pressure holding time of 250 s;

[0111] 3. Hot pressing and sintering: Heating rate of 8 °C / min, temperature of 240 °C, pressure of 45 MPa, and time of 3 h;

[0112] 4. Post-treatment: Deburring, polishing, and comprehensive inspection are carried out.

[0113] Comparative example 1

[0114] In this example, the brake pad efficiency enhancer is not added, and the remaining steps are the same as those in Example 1.

[0115] Comparative example 2

[0116] In this example, 2-[(thiophen-2-ylmethoxy)methyl]oxirane is not added during the preparation process of the brake pad efficiency enhancer, and the remaining steps are the same as those in Example 1.

[0117] Comparative example 3

[0118] In this example, ethanolamine thioglycolate is not added during the preparation process of the brake pad efficiency enhancer, and the remaining steps are the same as those in Example 1.

[0119] Testing method:

[0120] (1) Friction performance test

[0121] Testing standard: SAE J661 friction performance testing standard

[0122] Testing equipment: Friction testing machine

[0123] Testing conditions: Initial temperature of 25 °C, friction surface temperature rising to 300 °C, and measuring the friction coefficient

[0124] Table 1: Friction performance test results of examples and comparative examples

[0125] 25℃ 100℃ 200℃ 300℃ Example 1 0.38 0.39 0.40 0.39 Example 2 0.39 0.41 0.42 0.40 Example 3 0.41 0.42 0.43 0.42 Example 4 0.42 0.43 0.44 0.43 Comparative Example 1 0.34 0.35 0.33 0.30 Comparative Example 2 0.36 0.37 0.35 0.32 Comparative Example 3 0.36 0.36 0.35 0.33

[0126] (2) Abrasion Resistance Test

[0127] Test Standard: ISO 7148-2 Abrasion Resistance Test

[0128] Test Equipment: Friction and Wear Testing Machine

[0129] Test Method: Under the conditions of a constant pressure of 1.5 MPa and a rotational speed of 500 rpm, continuously friction for 10,000 times to measure the mass loss of the brake pads

[0130] Table 2: Test Results of Abrasion Resistance Performance for Examples and Comparative Examples

[0131] Mass loss mg Example 1 25 Example 2 23 Example 3 21 Example 4 20 Comparative Example 1 33 Comparative Example 2 30 Comparative Example 3 29

[0132] (3) High Temperature Stability Test

[0133] Test Standard: JASOC406 High Temperature Fade Test

[0134] Test Equipment: High Temperature Friction Testing Machine

[0135] Test Method: Keep the brake pads at 400 °C for 10 min to measure the change in friction coefficient

[0136] Table 3: Test Results of High Temperature Stability Performance for Examples and Comparative Examples

[0137] Coefficient of friction reduction rate (%) Example 1 5.2 Example 2 4.7 Example 3 4.4 Example 4 4.2 Comparative Example 1 6.7 Comparative Example 2 6.0 Comparative Example 3 6.1

[0138] From the above examples and test results, it can be seen that this method effectively improves the friction performance, abrasion resistance performance, and high temperature stability performance of the brake pads.

[0139] Of course, the present invention may also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a graphene-reinforced composite brake pad, characterized in that: The preparation was carried out using the following steps: (1) Ingredients: weigh each component according to the ratio of raw materials; (2) Mixing: adding graphene, nano-alumina, nano-silicon carbide, fiber reinforcement, filler, phenolic resin matrix, curing agent, lubricant, silane coupling agent and brake pad synergistic agent into a high-speed mixer, mixing at 500-1500 rpm for 30-120 min, or wet mixing at 300-800 rpm for 1-4 h using a planetary ball mill; (3) Preforming: The mixed material is placed in a mold and cold pressed at a pressure of 5-20 MPa, a molding temperature of 25-80°C, and a holding time of 30-300 s; (4) Hot pressing sintering: sintering at 150-250°C and 10-50 MPa for 1-3 h, with a heating rate of 2-10°C / min, to densify the composite material and improve its mechanical properties and wear resistance; (5) Post-processing and testing: trim the finished product to size, test hardness, friction coefficient, wear resistance and other indicators, and package and store; The brake pad synergistic aid is prepared by reacting 2-[(thiophene-2-ylmethoxy)methyl]ethylene oxide, thioglycolate ethanolamine, sodium hydroxide, allylphenylselenium and AIBN.

2. The method for preparing a graphene-enhanced composite brake pad according to claim 1, characterized in that: The ratio of the raw materials is calculated by mass: Graphene: 0.5-5 parts; Nano-alumina: 2-10 parts; Nano silicon carbide: 3-12 parts; Fiber reinforcement material: 5-20 parts; Phenolic resin matrix: 20-40 parts; Filler: 10-30 parts; Curing agent: 3-10 parts; Lubricant: 0.5-5 parts; Silane coupling agent: 0.1-1 part; Brake pad enhancement agent: 0.2-2 parts.

3. The method for preparing a graphene-enhanced composite brake pad according to claim 1, characterized in that: The graphene is a single-layer or few-layer graphene with a sheet diameter of 0.5-5 μm and a thickness of ≤10 nm.

4. The method for preparing a graphene-enhanced composite brake pad according to claim 1, characterized in that: The fiber reinforcement material includes at least one of glass fiber, aramid fiber and basalt fiber.

5. The method for preparing a graphene-enhanced composite brake pad according to claim 1, characterized in that: The filler includes at least one of barium sulfate, wollastonite, expanded graphite and mica powder.

6. The method for preparing a graphene-enhanced composite brake pad according to claim 1, characterized in that: The curing agent includes at least one of hexamethylenetetramine and benzenesulfonyl chloride.

7. The method for preparing a graphene-enhanced composite brake pad according to claim 1, characterized in that: The lubricant includes at least one of graphite and MoS2.

8. The method for preparing a graphene-enhanced composite brake pad according to claim 1, characterized in that: The silane coupling agent includes at least one of γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane and γ-glycidyloxypropyltrimethoxysilane.

9. The method for preparing a graphene-enhanced composite brake pad according to claim 1, characterized in that: Preparation method of the brake pad synergistic additive: Mercapto ring opening: Take 100 parts of 2-[(thiophen-2-ylmethoxy)methyl]ethylene oxide, add 120-150 parts of thioglycolic acid ethanolamine into a reaction vessel, add 5-10 parts of sodium hydroxide as a catalyst, and react at 40°C-60°C for 2-4 hours; Selenene addition: add 100-120 parts of allylphenylselenium and 1-3 parts of AIBN to the above system, initiate double bond addition at 60℃-80℃, react for 3-5 hours, and obtain a brake pad synergist.