Friction material for wear-resistant and heat-resistant brake pad and preparation method thereof

Abstract

This invention relates to the field of brake pad material technology, specifically disclosing a wear-resistant and heat-resistant friction material for brake pads and its preparation method. The invention uses phenolic resin as the binder matrix, compounded with carbon fiber, ceramic fiber, steel fiber, and potassium titanate whiskers to form a multi-component reinforcing system. It is further combined with specially formulated composite modified biochar material, mineral fillers, and lubricating and wear-resistant components in a synergistic formulation, with each component exhibiting complementary properties and synergistic effects. Specifically, the composite modified biochar material can form a dense, high-temperature protective friction film at the friction interface, effectively improving the material's heat resistance and high-temperature thermal degradation resistance, reducing high-temperature wear rate, and extending service life. Molybdenum disulfide and alumina synergistically regulate the friction coefficient, ensuring stability of the friction coefficient during braking and effectively reducing braking noise and wear on the mating disc. The friction material provided by this invention has the advantages of good wear and heat resistance, making it suitable for the high-intensity and demanding braking conditions required by heavy-duty vehicles and engineering machinery.

Description

Technical Field

[0001] This invention relates to the field of brake pad material technology, specifically to a wear-resistant and heat-resistant friction material for brake pads and its preparation method. Background Technology

[0002] Brake pads are an indispensable core safety component in the braking systems of passenger cars, commercial vehicles, and various construction machinery. They generate braking torque through frictional contact between the friction material and the brake disc, thereby enabling vehicle and equipment deceleration, parking, and emergency braking. Braking performance directly determines the safety and reliability of the vehicle and equipment operation. Under high-intensity and harsh operating conditions such as heavy-duty transportation, continuous braking on long downhill slopes in mountainous areas, and frequent start-stop braking of construction machinery, brake pad friction materials are subjected to high-intensity mechanical shear friction, instantaneous high-temperature thermal shock, and alternating load cycles, resulting in harsh operating environments. Therefore, friction materials must possess excellent high-temperature thermal stability, good wear resistance, a stable coefficient of friction, excellent structural mechanical strength, and excellent resistance to thermal fading. Simultaneously, they must also meet comprehensive application requirements such as low braking noise, minimal damage to the brake disc, and long service life. Through the coordinated matching of various key performance characteristics, the braking system can ensure stable braking response and consistently reliable braking effect across a wide temperature range and complex operating conditions, effectively avoiding safety risks such as brake failure and brake shudder.

[0003] In existing technologies, traditional brake pad friction materials mostly use phenolic resin as the binder matrix, compounded with conventional inorganic mineral fillers and single fiber reinforcement components, and are prepared by mixing and pressing. The overall formulation system and structural design of the material are relatively conventional, resulting in significant technical defects in comprehensive service performance, making it difficult to adapt to the harsh operating scenarios of high load and forced braking. Existing friction materials have low heat resistance temperatures. Under the high-temperature conditions generated by continuous braking, the resin matrix is ​​prone to thermal degradation, carbonization, and structural failure, causing a decrease in the internal bonding force and a loose microstructure of the friction material, which in turn leads to significant thermal degradation, resulting in large fluctuations in the coefficient of friction and a significant decrease in braking performance. At the same time, the wear-resistant reinforcement system of traditional friction materials is simple in design, resulting in high wear rate under high-temperature conditions, rapid wear after long-term service, short replacement cycle, and high equipment maintenance costs. Furthermore, the conventional carbon-based fillers and ordinary inorganic fillers added to existing friction materials are not modified, resulting in poor compatibility with the resin matrix interface, easy agglomeration and uneven dispersion of fillers, and difficulty in forming a continuous, dense and stable high-temperature wear-resistant protective friction film at the friction contact interface. This not only aggravates the wear and consumption of the friction material itself, but also easily causes abnormal wear of the brake mating disc, accompanied by braking noise, braking vibration and other defects. The overall comprehensive service performance is difficult to meet the actual application requirements of brake pad friction materials for current heavy-duty vehicles and high-end engineering machinery.

[0004] Therefore, how to further improve the wear resistance and heat resistance of brake pad friction materials has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a friction material for wear-resistant and heat-resistant brake pads and its preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A friction material for wear-resistant and heat-resistant brake pads, comprising the following raw materials by weight: 8-15 parts phenolic resin, 4-8 parts carbon fiber, 3-6 parts ceramic fiber, 2-4 parts steel fiber, 5-10 parts composite modified biochar material, 2-4 parts vermiculite powder, 3-6 parts rubber powder, 2-4 parts talc powder, 5-10 parts potassium titanate whiskers, 3-8 parts calcium carbonate, 1-3 parts molybdenum disulfide, and 2-4 parts alumina.

[0007] In the technical solution disclosed in this invention, the preparation method of the composite modified biochar material is as follows: S1. Preparation of phosphoric acid activated biochar Biochar was immersed in a phosphoric acid solution, heated and stirred, and then filtered, washed and dried to obtain phosphoric acid activated biochar.

[0008] In this step, the selected biochar has a particle size of 200-400 mesh.

[0009] In this step, the ratio of biochar to phosphoric acid solution is 10g:80-120mL, with the phosphoric acid solution having a mass fraction of 40-55%.

[0010] In this step, the heating and stirring process is carried out at a temperature of 75-85℃ for 2-4 hours.

[0011] In this step, phosphorylation activation is used, which is more targeted than traditional alkaline activation. The introduced phosphate group can not only react with La... 3+ Coordination pre-adsorption occurs, which guides LaPO4 to uniformly nucleate in situ on the surface of biochar, thereby improving the binding strength of the inorganic support layer.

[0012] S2. Preparation of Lanthanum Phosphate-Supported Biochar Composite Materials Phosphoric acid-activated biochar was dispersed in a mixed solvent of deionized water and ethylene glycol, followed by the addition of lanthanum salt and phosphate. The mixture underwent a hydrothermal reaction. After the reaction was completed, the biochar was washed, dried, and calcined to obtain a lanthanum phosphate-supported biochar composite material.

[0013] In this step, the ratio of phosphoric acid activated biochar to mixed solvent is 10g:150-250mL.

[0014] In this step, the volume ratio of deionized water to ethylene glycol in the mixed solvent is 4-5:1.

[0015] In this step, the molar ratio of lanthanum salt to phosphate is 1:1.05-1.2.

[0016] In this step, the lanthanum salt is selected from water-soluble lanthanum salts, such as lanthanum nitrate or lanthanum chloride.

[0017] In this step, the phosphate is selected from water-soluble phosphates, such as ammonium dihydrogen phosphate or disodium hydrogen phosphate.

[0018] In this step, the mass ratio of lanthanum salt to phosphoric acid activated biochar is 0.15-0.3:1. For example, 0.15:1, 0.2:1, 0.25:1, and 0.3:1 can be selected, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] In this step, the temperature of the hydrothermal reaction is 160-190℃, for example, 160℃, 170℃, 180℃, or 190℃ can be selected; the time of the hydrothermal reaction is 8-12h, for example, 8h, 9h, 10h, 11h, or 12h can be selected, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] In this step, by loading lanthanum phosphate onto biochar, the high melting point and excellent high-temperature phase structure stability of LaPO4 are utilized to form a dense, hard support skeleton at the friction interface to resist wear, thus endowing the composite filler with excellent friction reduction, wear resistance and high-temperature structural stability.

[0021] S3. Preparation of epoxy-grafted composite materials Lanthanum phosphate-supported biochar composite material was dispersed in an ethanol aqueous solution, the pH of the solution was adjusted to 4-5, and then silane coupling agent KH560 was added. After stirring, the solution was filtered, washed, and dried to obtain an epoxy-grafted composite material.

[0022] In this step, the ratio of lanthanum phosphate-supported biochar composite material to ethanol aqueous solution is 10g:150-200mL.

[0023] In this step, the volume ratio of the selected ethanol-water solution is 3-4:1.

[0024] In this step, the mass ratio of lanthanum phosphate-supported biochar composite material to silane coupling agent KH560 is 10:0.8-1.5. For example, 10:0.8, 10:0.9, 10:1, 10:1.1, 10:1.2, 10:1.3, 10:1.4, and 10:1.5 can be selected, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] In this step, introducing epoxy groups onto the surface of the composite filler facilitates subsequent reactions.

[0026] S4. Preparation of composite modified biochar materials 2-(4-aminophenyl)-5-aminobenzimidazole was dissolved in N-methylpyrrolidone, and then epoxy-grafted composite material and triethylamine were added to it. The mixture was heated to react. After the reaction was completed, the mixture was filtered, washed and dried to obtain the composite modified biochar material.

[0027] In this step, the mass ratio of the epoxy-grafted composite material, 2-(4-aminophenyl)-5-aminobenzimidazole, and triethylamine is 10:2-4:0.8-1.5.

[0028] In this step, the temperature of the heating reaction is 120-140℃, for example, 120℃, 125℃, 130℃, 135℃, 140℃ can be selected; the heating reaction time is 4-8h, for example, 4h, 5h, 6h, 7h, 8h can be selected, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] In this step, by grafting 2-(4-aminophenyl)-5-aminobenzimidazole onto the surface of the composite material, a high-temperature stable covalent bonded interface layer is constructed between the filler particles and the phenolic resin matrix, thanks to the rigid heterocyclic structure and high thermal stability of benzimidazole. This significantly improves the interfacial compatibility and bonding strength between the two, thereby effectively preventing the interfacial peeling and detachment of the filler particles under high-temperature and heavy-load conditions, and thus improving the overall heat resistance and wear resistance of the friction material.

[0030] The present invention also provides a method for preparing the above-mentioned friction material for wear-resistant and heat-resistant brake pads, comprising the following steps: uniformly mixing each component according to the formula to obtain a mixed raw material, placing the mixed raw material in a molding cavity for molding treatment, and then performing heat treatment to obtain the friction material for wear-resistant and heat-resistant brake pads.

[0031] The specific molding process is as follows: press at 160-180℃ and 30-40MPa for 6-8 minutes, and vent air 5-6 times during the first 3 minutes of hot pressing.

[0032] The specific process for heat treatment is to hold the temperature at 170-190℃ for 4-6 hours.

[0033] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention uses phenolic resin as the binder matrix, and combines it with carbon fiber, ceramic fiber, steel fiber and potassium titanate whiskers to form a multi-component reinforcing system. It is combined with specially made composite modified biochar material and mineral filler and lubricating and wear-resistant components to complement each other and enhance the performance of each component. Among them, the composite modified biochar material can form a dense high-temperature protective friction film at the friction interface, which can effectively improve the material's heat resistance and high-temperature heat fading resistance, reduce the high-temperature wear rate and extend the service life. Molybdenum disulfide and alumina synergistically regulate the friction coefficient to ensure the stability of the friction coefficient during the braking process, effectively reducing braking noise and wear of the mating disc. The friction material provided by this invention has the advantages of good wear resistance and heat resistance, and is suitable for the high-intensity and harsh braking conditions of heavy-duty vehicles and engineering machinery.

[0034] (2) The present invention uses phosphorylation activation treatment, which is more targeted than traditional alkaline activation treatment. The introduced phosphate group can not only react with La 3+ Coordination pre-adsorption occurs, guiding LaPO4 to uniformly nucleate in situ on the surface of biochar, thereby improving the bonding strength of the inorganic support layer. This invention loads lanthanum phosphate onto biochar and utilizes the high melting point and excellent high-temperature phase structure stability of LaPO4 to form a dense, hard support skeleton at the friction interface to resist wear, thus endowing the composite filler with excellent friction reduction, wear resistance, and high-temperature structural stability.

[0035] (3) By grafting 2-(4-aminophenyl)-5-aminobenzimidazole onto the surface of the composite material, the present invention utilizes the rigid heterocyclic structure and ultra-high thermal stability of benzimidazole to construct a high-temperature stable covalent bonded interface layer between the filler particles and the phenolic resin matrix, which significantly improves the interfacial compatibility and bonding strength between the two, thereby effectively preventing the interfacial peeling and detachment of the filler particles under high temperature and heavy load conditions, and thus improving the overall heat resistance and wear resistance of the friction material. Detailed Implementation

[0036] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0037] It should be noted that, unless otherwise specified, all chemical reagents involved in this invention were purchased through commercial channels.

[0038] The phenolic resin used in this embodiment has the CAS number 9003-35-4; the carbon fiber has a length of 1-3 mm and a diameter of 6-7 μm; the ceramic fiber has a length of 80-300 μm and a diameter of 0.5-2 μm; the steel fiber has a length of 5-8 mm and a diameter of 10-15 μm; the vermiculite powder has a mesh size of 400 mesh; the rubber powder is nitrile rubber powder with a mesh size of 200 mesh; the talc powder has a mesh size of 200 mesh; the potassium titanate whiskers have a length of 30-50 μm and a diameter of 1-3 μm; the calcium carbonate has a mesh size of 400 mesh; the molybdenum disulfide has a mesh size of 1250 mesh; the alumina has a particle size of 10-20 μm; and the biochar is coconut shell biochar with a mesh size of 400 mesh.

[0039] Example 1

[0040] A method for preparing a friction material for wear-resistant and heat-resistant brake pads includes the following steps: Ten parts of phenolic resin, six parts of carbon fiber, five parts of ceramic fiber, three parts of steel fiber, eight parts of composite modified biochar material, three parts of vermiculite powder, five parts of rubber powder, three parts of talc powder, eight parts of potassium titanate whiskers, five parts of calcium carbonate, two parts of molybdenum disulfide, and three parts of alumina were added to a high-speed mixer and mixed evenly to obtain a mixed raw material. The resulting mixed raw material was placed in a molding cavity for molding treatment. The specific molding process was as follows: pressing at 180℃ and 30MPa for 6 minutes, venting five times during the first 3 minutes of hot pressing, and then holding at 180℃ for 5 hours to obtain a friction material for wear-resistant and heat-resistant brake pads.

[0041] The preparation method of the composite modified biochar material is as follows: S1. 10g of biochar was immersed in 100mL of 40wt% phosphoric acid solution and heated and stirred at 80℃ for 3h. After filtration, washing and drying, phosphoric acid activated biochar was obtained. S2. 10g of phosphoric acid activated biochar was dispersed in a mixed solvent of 160mL deionized water and 40mL ethylene glycol. Then, 2g of lanthanum nitrate and 0.64g of ammonium dihydrogen phosphate were added. The mixture was hydrothermally reacted at 190℃ for 8h. After the reaction was completed, the mixture was washed, dried, and calcined at 500℃ for 2h under a nitrogen atmosphere to obtain a lanthanum phosphate supported biochar composite material. S3. 10g of lanthanum phosphate-supported biochar composite material was dispersed in 150mL of ethanol aqueous solution with a volume ratio of ethanol to water of 4:1. The pH of the solution was adjusted to 5. Then, 1g of silane coupling agent KH560 was added and stirred at room temperature for 3h. After filtration, washing and drying, epoxy-grafted composite material was obtained. S4. Dissolve 3g of 2-(4-aminophenyl)-5-aminobenzimidazole in 150mL of N-methylpyrrolidone, then add 10g of epoxy-grafted composite material and 1g of triethylamine to the solution, and heat at 140℃ for 4h. After the reaction is complete, filter, wash and dry to obtain the composite modified biochar material.

[0042] Example 2

[0043] A method for preparing a friction material for wear-resistant and heat-resistant brake pads includes the following steps: Eight parts of phenolic resin, four parts of carbon fiber, three parts of ceramic fiber, two parts of steel fiber, five parts of composite modified biochar material, two parts of vermiculite powder, three parts of rubber powder, two parts of talc powder, five parts of potassium titanate whiskers, three parts of calcium carbonate, one part of molybdenum disulfide, and two parts of alumina were added to a high-speed mixer and mixed evenly to obtain a mixed raw material. The resulting mixed raw material was placed in a molding cavity for molding treatment. The specific molding process was as follows: pressing at 180℃ and 30MPa for 6 minutes, venting five times during the first 3 minutes of hot pressing, and then holding at 180℃ for 5 hours to obtain a friction material for wear-resistant and heat-resistant brake pads.

[0044] The preparation method of the composite modified biochar material is as follows: S1. 10g of biochar was immersed in 100mL of 40wt% phosphoric acid solution and heated and stirred at 80℃ for 3h. After filtration, washing and drying, phosphoric acid activated biochar was obtained. S2. 10g of phosphoric acid activated biochar was dispersed in a mixed solvent of 160mL deionized water and 40mL ethylene glycol. Then, 2g of lanthanum nitrate hexahydrate and 0.64g of ammonium dihydrogen phosphate were added. The mixture was hydrothermally reacted at 190℃ for 8h. After the reaction was completed, the mixture was washed, dried, and calcined at 500℃ for 2h under a nitrogen atmosphere to obtain a lanthanum phosphate supported biochar composite material. S3. 10g of lanthanum phosphate-supported biochar composite material was dispersed in 150mL of ethanol aqueous solution with a volume ratio of ethanol to water of 4:1. The pH of the solution was adjusted to 5. Then, 1g of silane coupling agent KH560 was added and stirred at room temperature for 3h. After filtration, washing and drying, epoxy-grafted composite material was obtained. S4. Dissolve 2g of 2-(4-aminophenyl)-5-aminobenzimidazole in 150mL of N-methylpyrrolidone, then add 10g of epoxy-grafted composite material and 0.8g of triethylamine to the solution. Heat the mixture at 140℃ for 4h. After the reaction is complete, filter, wash and dry to obtain the composite modified biochar material.

[0045] Example 3

[0046] A method for preparing a friction material for wear-resistant and heat-resistant brake pads includes the following steps: 15 parts phenolic resin, 8 parts carbon fiber, 6 parts ceramic fiber, 4 parts steel fiber, 10 parts composite modified biochar material, 4 parts vermiculite powder, 6 parts rubber powder, 4 parts talc powder, 10 parts potassium titanate whiskers, 8 parts calcium carbonate, 3 parts molybdenum disulfide and 4 parts alumina were added to a high-speed mixer and mixed evenly to obtain a mixed raw material. The obtained mixed raw material was placed in a molding cavity for molding treatment. The specific molding treatment process was as follows: pressing at 180℃ and 30MPa for 6 minutes, venting 5 times during the first 3 minutes of hot pressing, and then holding at 180℃ for 5 hours to obtain the friction material for wear-resistant and heat-resistant brake pads.

[0047] The preparation method of the composite modified biochar material is as follows: S1. 10g of biochar was immersed in 100mL of 40wt% phosphoric acid solution and heated and stirred at 80℃ for 3h. After filtration, washing and drying, phosphoric acid activated biochar was obtained. S2. 10g of phosphoric acid activated biochar was dispersed in a mixed solvent of 160mL deionized water and 40mL ethylene glycol. Then, 2g of lanthanum nitrate hexahydrate and 0.64g of ammonium dihydrogen phosphate were added. The mixture was hydrothermally reacted at 190℃ for 8h. After the reaction was completed, the mixture was washed, dried, and calcined at 500℃ for 2h under a nitrogen atmosphere to obtain a lanthanum phosphate supported biochar composite material. S3. 10g of lanthanum phosphate-supported biochar composite material was dispersed in 150mL of ethanol aqueous solution with a volume ratio of ethanol to water of 4:1. The pH of the solution was adjusted to 5. Then, 1.5g of silane coupling agent KH560 was added and stirred at room temperature for 3h. After filtration, washing and drying, epoxy-grafted composite material was obtained. S4. Dissolve 4g of 2-(4-aminophenyl)-5-aminobenzimidazole in 150mL of N-methylpyrrolidone, then add 10g of epoxy-grafted composite material and 1.5g of triethylamine to the solution, heat at 140℃ for 4h, and after the reaction is complete, filter, wash and dry to obtain the composite modified biochar material.

[0048] Comparative Example 1

[0049] A method for preparing a friction material for wear-resistant and heat-resistant brake pads includes the following steps: Ten parts of phenolic resin, six parts of carbon fiber, five parts of ceramic fiber, three parts of steel fiber, eight parts of composite modified biochar material, three parts of vermiculite powder, five parts of rubber powder, three parts of talc powder, eight parts of potassium titanate whiskers, five parts of calcium carbonate, two parts of molybdenum disulfide, and three parts of alumina were added to a high-speed mixer and mixed evenly to obtain a mixed raw material. The resulting mixed raw material was placed in a molding cavity for molding treatment. The specific molding process was as follows: pressing at 180℃ and 30MPa for 6 minutes, venting five times during the first 3 minutes of hot pressing, and then holding at 180℃ for 5 hours to obtain a friction material for wear-resistant and heat-resistant brake pads.

[0050] The preparation method of the composite modified biochar material is as follows: S1. Immerse 10g of biochar in 100mL of 1mol / L NaOH solution, heat and stir at 80℃ for 3h, then filter, wash and dry to obtain activated biochar; S2. 10g of activated biochar was dispersed in a mixed solvent of 160mL deionized water and 40mL ethylene glycol, followed by the addition of 2g of lanthanum nitrate and 0.64g of ammonium dihydrogen phosphate. The mixture was hydrothermally reacted at 190℃ for 8h. After the reaction was completed, the mixture was washed, dried, and calcined at 500℃ for 2h under a nitrogen atmosphere to obtain a lanthanum phosphate-supported biochar composite material. S3. 10g of lanthanum phosphate-supported biochar composite material was dispersed in 150mL of ethanol aqueous solution with a volume ratio of ethanol to water of 4:1. The pH of the solution was adjusted to 5. Then, 1g of silane coupling agent KH560 was added and stirred at room temperature for 3h. After filtration, washing and drying, epoxy-grafted composite material was obtained. S4. Dissolve 3g of 2-(4-aminophenyl)-5-aminobenzimidazole in 150mL of N-methylpyrrolidone, then add 10g of epoxy-grafted composite material and 1g of triethylamine to the solution, and heat at 140℃ for 4h. After the reaction is complete, filter, wash and dry to obtain the composite modified biochar material.

[0051] Compared with Example 1, NaOH solution was used instead of phosphoric acid solution for activation treatment in Comparative Example 1.

[0052] Comparative Example 2

[0053] A method for preparing a friction material for wear-resistant and heat-resistant brake pads includes the following steps: Ten parts of phenolic resin, six parts of carbon fiber, five parts of ceramic fiber, three parts of steel fiber, eight parts of composite modified biochar material, three parts of vermiculite powder, five parts of rubber powder, three parts of talc powder, eight parts of potassium titanate whiskers, five parts of calcium carbonate, two parts of molybdenum disulfide, and three parts of alumina were added to a high-speed mixer and mixed evenly to obtain a mixed raw material. The resulting mixed raw material was placed in a molding cavity for molding treatment. The specific molding process was as follows: pressing at 180℃ and 30MPa for 6 minutes, venting five times during the first 3 minutes of hot pressing, and then holding at 180℃ for 5 hours to obtain a friction material for wear-resistant and heat-resistant brake pads.

[0054] The preparation method of the composite modified biochar material is as follows: S1. 10g of biochar was immersed in 100mL of 40wt% phosphoric acid solution and heated and stirred at 80℃ for 3h. After filtration, washing and drying, phosphoric acid activated biochar was obtained. S2. Disperse 10g of phosphoric acid activated biochar in 150mL of ethanol aqueous solution with a volume ratio of ethanol to water of 4:1. Adjust the pH of the solution to 5. Then add 1g of silane coupling agent KH560 and stir at room temperature for 3h. After filtration, washing and drying, epoxy-grafted biochar material is obtained. S3. Dissolve 3g of 2-(4-aminophenyl)-5-aminobenzimidazole in 150mL of N-methylpyrrolidone, then add 10g of epoxy-grafted biochar material and 1g of triethylamine to the solution, and heat at 140℃ for 4h. After the reaction is complete, filter, wash and dry to obtain the composite modified biochar material.

[0055] Compared to Comparative Example 2 and Example 1, the biochar did not have lanthanum phosphate loaded on it.

[0056] Comparative Example 3

[0057] A method for preparing a friction material for wear-resistant and heat-resistant brake pads includes the following steps: Ten parts of phenolic resin, six parts of carbon fiber, five parts of ceramic fiber, three parts of steel fiber, eight parts of composite modified biochar material, three parts of vermiculite powder, five parts of rubber powder, three parts of talc powder, eight parts of potassium titanate whiskers, five parts of calcium carbonate, two parts of molybdenum disulfide, and three parts of alumina were added to a high-speed mixer and mixed evenly to obtain a mixed raw material. The resulting mixed raw material was placed in a molding cavity for molding treatment. The specific molding process was as follows: pressing at 180℃ and 30MPa for 6 minutes, venting five times during the first 3 minutes of hot pressing, and then holding at 180℃ for 5 hours to obtain a friction material for wear-resistant and heat-resistant brake pads.

[0058] The preparation method of the composite modified biochar material is as follows: S1. 10g of biochar was immersed in 100mL of 40wt% phosphoric acid solution and heated and stirred at 80℃ for 3h. After filtration, washing and drying, phosphoric acid activated biochar was obtained. S2. 10g of phosphoric acid activated biochar was dispersed in a mixed solvent of 160mL deionized water and 40mL ethylene glycol. Then, 2g of lanthanum nitrate and 0.64g of ammonium dihydrogen phosphate were added. The mixture was hydrothermally reacted at 190℃ for 8h. After the reaction was completed, the mixture was washed, dried, and calcined at 500℃ for 2h under a nitrogen atmosphere to obtain a lanthanum phosphate supported biochar composite material. S3. Disperse 10g of lanthanum phosphate-supported biochar composite material in 150mL of ethanol-water solution with a volume ratio of ethanol to water of 4:1. Adjust the pH of the solution to 5, then add 1g of silane coupling agent KH560 and stir at room temperature for 3h. After filtration, washing and drying, the composite modified biochar material is obtained.

[0059] Compared with Example 1, Comparative Example 3 did not have 2-(4-aminophenyl)-5-aminobenzimidazole grafted onto it.

[0060] The friction materials prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests. The coefficient of friction and wear rate were tested according to standard GB 5763-2018 "Automotive Brake Liners". The thermogravimetric analysis (Td) (5% thermogravimetric temperature) was tested according to standard GB / T 44307-2024 "Determination of Fiber Mass Content of Carbon Fiber Reinforced Plastics - Thermogravimetric Analysis (TG)" with a heating rate of 10℃ / min and a temperature range from room temperature to 800℃. The test results are shown in Table 1.

[0061] Table 1 Performance test results for different groups

[0062] As can be seen from the table, compared with comparative examples 1-3, the friction materials prepared in the embodiments of the present invention have excellent wear resistance and high temperature resistance.

[0063] Finally, it should be noted that the above embodiments do not limit the present invention in any way. Those skilled in the art can make modifications and improvements based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A friction material for wear-resistant and heat-resistant brake pads, characterized in that, By weight, it includes the following raw materials: 8-15 parts phenolic resin, 4-8 parts carbon fiber, 3-6 parts ceramic fiber, 2-4 parts steel fiber, 5-10 parts composite modified biochar material, 2-4 parts vermiculite powder, 3-6 parts rubber powder, 2-4 parts talc powder, 5-10 parts potassium titanate whiskers, 3-8 parts calcium carbonate, 1-3 parts molybdenum disulfide, and 2-4 parts alumina.

2. The friction material for wear-resistant and heat-resistant brake pads according to claim 1, characterized in that, The preparation method of the composite modified biochar material is as follows: S1. Immerse biochar in phosphoric acid solution, heat and stir, then filter, wash and dry to obtain phosphoric acid activated biochar; S2. Activated biochar with phosphoric acid is dispersed in a mixed solvent of deionized water and ethylene glycol, followed by the addition of lanthanum salt and phosphate. The reaction is carried out hydrothermally. After the reaction is completed, the biochar composite material is obtained by washing, drying and calcining. S3. Lanthanum phosphate-supported biochar composite material is dispersed in an ethanol aqueous solution, the pH of the solution is adjusted to 4-5, then silane coupling agent KH560 is added, the mixture is stirred, and then filtered, washed and dried to obtain epoxy-grafted composite material. S4. Dissolve 2-(4-aminophenyl)-5-aminobenzimidazole in N-methylpyrrolidone, then add epoxy-grafted composite material and triethylamine to it, heat to react, and after the reaction is completed, filter, wash and dry to obtain composite modified biochar material.

3. The friction material for wear-resistant and heat-resistant brake pads according to claim 2, characterized in that, In step S1, the heating and stirring treatment temperature is 75-85℃, and the heating and stirring treatment time is 2-4 hours.

4. The friction material for wear-resistant and heat-resistant brake pads according to claim 2, characterized in that, In step S2, the molar ratio of lanthanum salt to phosphate is 1:1.05-1.

2.

5. The friction material for wear-resistant and heat-resistant brake pads according to claim 2, characterized in that, In step S2, the mass ratio of lanthanum salt to phosphoric acid activated biochar is 0.15-0.3:

1.

6. The friction material for wear-resistant and heat-resistant brake pads according to claim 2, characterized in that, In step S2, the hydrothermal reaction temperature is 160-190℃, and the hydrothermal reaction time is 8-12h.

7. The friction material for wear-resistant and heat-resistant brake pads according to claim 2, characterized in that, In step S3, the mass ratio of lanthanum phosphate-supported biochar composite material to silane coupling agent KH560 is 10:0.8-1.

5.

8. The friction material for wear-resistant and heat-resistant brake pads according to claim 2, characterized in that, In step S4, the mass ratio of the epoxy-grafted composite material, 2-(4-aminophenyl)-5-aminobenzimidazole, and triethylamine is 10:2-4:0.8-1.

5.

9. The friction material for wear-resistant and heat-resistant brake pads according to claim 2, characterized in that, In step S4, the temperature of the heating reaction is 120-140℃, and the heating reaction time is 4-8h.

10. The method for preparing the friction material for wear-resistant and heat-resistant brake pads as described in any one of claims 1-9, characterized in that, The process includes the following steps: uniformly mixing each component according to the formula to obtain a mixed raw material; placing the mixed raw material in a molding cavity for molding; and then performing heat treatment to obtain a friction material for wear-resistant and heat-resistant brake pads.

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