Preparation method of high-performance semimetal composite brake pad

Abstract

The invention discloses a preparation method of a high-performance semimetal composite brake pad, and relates to the technical field of automobile brake part manufacturing. By optimizing the formula and the preparation process of the friction material and adopting the combination of the ceramic fiber, the metal fiber, the special resin, the copper-free or low-copper filler and the high-temperature stable lubricant, the high temperature resistance, the wear resistance, the friction stability and the environmental protection performance of the brake pad are remarkably improved. According to the brake pad, the high-temperature stability and wear resistance of the brake pad are improved, noise and vibration can be effectively reduced, and the driving and riding comfort is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile brake component manufacturing, and particularly relates to a preparation method of a high-performance semi-metal composite brake pad. BACKGROUND

[0002] The brake pad (or brake lining) is one end of the friction pair in the vehicle braking system, and its performance is directly related to driving safety. In actual use, the brake pad must withstand high temperature, humidity, friction, impact and other extreme working conditions. In recent years, with the increasingly stringent environmental protection regulations (especially the restrictions on asbestos, heavy metals such as copper, lead and cadmium), and the increasing requirements of consumers on braking performance (braking distance, thermal decay / stability, wear resistance, noise and vibration, etc.), the brake pad material and preparation process have become an important research direction in the field of friction materials.

[0003] When the brake is frequently used or braked for a long time (such as downhill, towing, sports driving, etc.), the friction interface temperature can reach several hundred degrees (usually 300-500 DEG C or higher). At this temperature, some resin binders, lubricants and fillers will decompose or soften, reducing the friction coefficient and braking force. This requires the material to have a stable friction coefficient and thermal expansion / thermal stress resistance at high temperatures.

[0004] Friction process can cause abrasive wear, interface wear, surface cracking, spalling, etc. If the wear rate is high, not only the service life of the brake pad itself is short, but also the brake disc wear may be aggravated, and the maintenance cost is high.

[0005] Vibration, friction instability or surface film layer changes during the friction process can cause brake noise (squeal or squeak). This is closely related to the material components (such as the distribution of hard particles, fiber types and lengths, the presence and form of lubricants / regulators).

[0006] Many national regulations have banned the use of asbestos materials in friction materials, limited the content of heavy metals (especially copper), and required dust emission and release of toxic substances to meet standards. For example, some states in the United States require that the copper content of brake materials be reduced to a certain threshold after 2020. At the same time, consumers are also increasingly concerned about the release of volatile or irritating substances in brake dust.

[0007] CN102180618A, by weight percentage, contains 5-15% ceramic fiber, 5-15% mineral fiber, 5-10% resin, 5-10% copper (or copper "copper glance powder"), 10-20% graphite, 10-20% barite (BaSO4), 3-15% bio-calcified particles, 3-10% coke, 10-20% anti-friction agent, and 5-10% performance modifier and filler, bringing the total composition to 100%. Its advantages include a relatively comprehensive formulation, a relatively stable coefficient of friction during temperature rise / fall cycles, low wear rate, and long service life. Disadvantages include a high copper content, the potential failure of some lubricants or heat-resistant agents at extremely high temperatures, and a lack of deep optimization for thermal cracking or high-temperature structural stability.

[0008] US Patent 8863917 (“Friction material for brakes” — Federal-Mogul) describes a non-asbestos friction material containing approximately 16-24 vol% resin binder (e.g., phenolic resin), 4-12 vol% fiber (e.g., aramid fiber), 2-5 vol% lubricant mixture (e.g., antimony trisulfide or other metal sulfides), 10-22 vol% abrasive (mineral fibers, magnesium oxide, mica, etc.), and ≥ 4 vol% rubber powder. Advantages include a balance between lubricity, abrasion resistance, and noise in the volume percentage design; disadvantages may include limited comparability between volume and mass percentages, and poor stability of certain components (e.g., lubricant or metal fibers) under extremely high temperatures or extreme loads.

[0009] CN108138031B proposes a friction material formulation for disc brake pads that is copper-free (NAO). It contains monoclinic zirconia as an inorganic friction modifier, with an average particle size of 1-8 µm, accounting for 10-40 wt%; it contains ≥ 1.5 wt% elastic graphitized carbon; and 2-8 wt% calcined coke. The weight ratio of elastic graphitized carbon to coke is between 4:6 and 8:2. Additionally, it may contain layered mineral particles as auxiliary inorganic modifiers. The advantages are enhanced wear resistance and braking stability under high temperature and high load conditions, and improved environmental friendliness by reducing copper usage. Disadvantages may lie in cost or process complexity (e.g., difficulty in dispersing fine zirconia particles, and high precision requirements for the ratio of elastic graphitized carbon to coke).

[0010] Based on the above literature and actual usage, the following problems still exist in the existing technology that have not been well resolved:

[0011] 1. The fluctuation and decay of the friction coefficient under high temperature and high load are still significant.

[0012] Although some patents, such as CN102180618A, propose formulations with smaller fluctuations in the coefficient of friction during the temperature rise / fall cycle (e.g., 0.35-0.40 during the temperature rise period and 0.33-0.44 during the temperature fall period), these formulations may not perform well under more extreme conditions (e.g., continuous high-speed braking for a long time, humid and hot environments, large temperature differences between brake discs and brake pads).

[0013] 2. There is still room for improvement in wear rate and structural stability under extreme use.

[0014] In patent CN108138031B, copper-free NAO materials improve wear resistance by adjusting zirconium oxide. However, although the mixture of elastic graphite and coke provides lubrication and reduces wear, the microstructure (fiber-particle interface, resin-filler interface) may be weaker than ceramic fiber reinforced and high-temperature resin reinforced materials under thermal stress (such as thermal cycling and thermal shock) or cumulative load on the friction interface.

[0015] 3. A trade-off between environmental requirements and costs

[0016] Reducing the use of metals such as copper to improve environmental friendliness (e.g., CN108138031B) is a trend. On the other hand, high-performance ceramic fibers, nanoparticles, and special lubricants increase costs and the complexity of the preparation process. Raw material dispersibility, dust safety, resin temperature resistance, and material consistency still need to be optimized.

[0017] 4. Insufficient optimization of composite structure and fiber type combination

[0018] The mixing ratio, length, diameter, and distribution of different fibers (such as ceramic fibers, aramid fibers, metal fibers, and mineral fibers) have a significant impact on material properties. Some existing patent formulations emphasize certain fibers, but research on fiber thermal stability, thermal expansion matching, fiber-resin interfacial bonding strength, and the overall synergistic performance of composite filler combinations (hard particles + lubricant + fiber + resin) is still insufficient. Summary of the Invention

[0019] Based on the problems mentioned above in the background technology, this invention proposes a method for preparing high-performance semi-metallic composite brake pads, the technical solution of which is as follows:

[0020] A method for preparing a high-performance semi-metallic composite brake pad includes the following steps, in parts by weight:

[0021] a) Raw materials

[0022] Ceramic fiber: 8-15 parts, crushed to a length of 0.5-5 mm;

[0023] Aramid fiber: 5-10 parts, crushed to a length of 0.5-5 mm;

[0024] Inorganic fibers: 3-6 parts;

[0025] Metal powder: 6-12 parts, dried to a moisture content of < 0.5%;

[0026] Friction modifier: 1-5 parts, particle size < 100 nm;

[0027] Graphite: 5-9 parts, flake graphite or expanded graphite;

[0028] Inert minerals: 15-30 parts;

[0029] Resin binder: 15-25 parts;

[0030] b) Ingredients and Mixing

[0031] Weigh and mix all solid components according to the above proportions, add 25-45 parts of organic solvent as a medium mixing agent, and mix by ball milling for 5-20 minutes to ensure uniform distribution of components;

[0032] c) Drying / Dehydration / Removal of Solvents

[0033] Preliminary drying: 60-100 ℃, for 1-3 hours;

[0034] Secondary drying: 120-150 ℃, 2-4 hours, until the moisture content or residual solvent is < 1 wt%;

[0035] d) Compression molding

[0036] The dried mixture is placed into a mold and molded under a pressure of 18-35 MPa and a temperature of 80-120℃ for 2-10 minutes to achieve initial shaping.

[0037] e) Laminated with a metal backing

[0038] The backing plate is made of corrosion-resistant steel plate or galvanized steel plate, with a thickness of 2-5 mm; it can be laminated during molding or hot pressing; the lamination pressure is the same as the molding pressure.

[0039] f) Thermosetting / High-temperature sintering / Hot pressing curing

[0040] Temperature range: 250-300 ℃;

[0041] Pressure range 15-30 MPa;

[0042] Keep it on for 10-30 minutes;

[0043] g) Machining / Finishing

[0044] Remove burrs, grind the surface, and if grooving or drilling is required, the groove depth and hole diameter shall be determined according to the brake disc design requirements; the final friction surface roughness shall be controlled within Ra 1.0-3.0 µm.

[0045] In a preferred embodiment of the present invention, the ceramic fiber is selected from alumina fiber or mullite fiber.

[0046] In a preferred embodiment of the invention, the aramid fiber is a commercially available Aramid® polymer fiber, selected from DSM Kevlar or Kolon Twaron.

[0047] In a preferred embodiment of the present invention, the inorganic fiber is selected from at least one of talc fiber, mica fiber or calcium / magnesium silicate fiber.

[0048] In a preferred embodiment of the present invention, the metal powder is selected from copper fiber or copper alloy powder.

[0049] In a preferred embodiment of the present invention, the friction modifier nanoparticles are selected from one or more of molybdenum disulfide, zinc oxide, chromium oxide, and iron oxide nanoparticles.

[0050] In a preferred embodiment of the present invention, the inert mineral is selected from one or more of vermiculite, mica, talc, barite, zirconium silicate, and potassium feldspar.

[0051] In a preferred embodiment of the present invention, the method for preparing the resin binder is as follows:

[0052] A1: According to the mass fractions, add 40-60 parts of bisphenol A type epoxy resin (epoxy value 0.48-0.54 eq / 100g), 1.5-3 parts of epoxy succinic acid polymer (CAS No.: 51274-37-4), 0.5-2 parts of dimethyl 2-aminothiophene-3,4-dicarboxylate (CAS No. 1520161-91-4), 5-15 parts of polyetheramine D230, 80-120 parts of ethylene glycol monomethyl ether, and 0.5-2 parts of triethanolamine to a reaction vessel, control the stirring speed at 300-500 rpm, and react at 60-70℃ for 1.5-3 hours;

[0053] A2: After the reaction is complete, the reaction solution is transferred to a rotary evaporator and distilled at a vacuum of 0.08-0.1 MPa and 80-100℃ for 2-4 hours to remove all solvents. Then, the viscous resin is transferred to a forced-air drying oven and dried at 120-140℃ for 3-5 hours to form solid resin blocks. Finally, the resin blocks are crushed with a jaw crusher, processed by an air jet mill, and passed through a 100-200 mesh sieve to obtain the resin binder.

[0054] In a preferred embodiment of the present invention, the organic solvent is selected from isopropanol or ethanol.

[0055] Reaction mechanism of resin binders:

[0056] 1. Main crosslinking network construction reaction

[0057] The core reaction of the resin binder begins with the multi-component cross-linking reaction in step A1, using bisphenol A type epoxy resin as the matrix. The epoxy three-membered rings at the molecular chain ends exhibit high reactivity. Under heating conditions, the amino groups in polyetheramine D230 and dimethyl 2-aminothiophene-3,4-dicarboxylate act as active groups, attacking the epoxy three-membered ring: the active hydrogen in the amino group combines with the oxygen on the epoxy ring, causing the three-membered ring to open and generate hydroxyl groups. These hydroxyl groups further undergo etherification with unreacted epoxy groups, ultimately forming "epoxy-amine" cross-linking bonds between the epoxy resin molecular chains, connecting the originally linear epoxy resin molecules into a three-dimensional network main structure. In this process, triethanolamine plays a dual role: its tertiary amine groups can activate the epoxy groups, accelerating the reaction rate with the amino groups; simultaneously, its own hydroxyl groups can also undergo etherification with the epoxy groups, supplementing cross-linking sites and enhancing the compactness of the main cross-linking network.

[0058] 2. Secondary cross-linking and concerted reaction

[0059] Epoxysuccinic acid polymers participate in synergistic crosslinking in the reaction system, further refining the molecular structure. The polymer molecular chain contains both epoxy and carboxyl groups: the epoxy groups can undergo ring-opening crosslinking reactions with the amino groups in polyetheramine D230 and dimethyl 2-aminothiophene-3,4-dicarboxylate, forming additional "epoxy-amine" bonds; the carboxyl groups can undergo esterification reactions with the hydroxyl groups generated after ring-opening of bisphenol A epoxy resin, forming "carboxyl-hydroxyl" crosslinking bonds. These crosslinking bonds formed by the epoxysuccinic acid polymer serve as secondary crosslinking sites interspersed within the main crosslinking network, not only increasing the overall crosslinking density but also optimizing the structural stability of the crosslinking network through the synergistic effect of different types of chemical bonds, laying the molecular structural foundation for the subsequent performance of the resin binder.

[0060] Beneficial effects of resin binders:

[0061] 1. Excellent mechanical and tribological properties

[0062] When this resin binder is applied to brake pads, its high-density three-dimensional network structure significantly increases its hardness compared to ordinary resins, providing stable support for internal components. The polar groups form strong chemical bonds with the metal matrix, greatly enhancing interfacial bonding strength and preventing "chipping" and delamination. Simultaneously, the high cross-linking density and post-curing treatment enhance the resin's thermal stability, preventing thermal softening during braking and maintaining a stable coefficient of friction. Furthermore, the dense structure and passivation film effectively reduce wear, ensuring braking stability and product durability.

[0063] 2. Excellent environmental adaptability and process compatibility.

[0064] In terms of environmental adaptability, the flexibility of polyetheramine D230 can alleviate high-temperature internal stress, and the heterocyclic structure of dimethyl 2-aminothiophene-3,4-dicarboxylate can inhibit oxidative degradation, maintaining good bonding strength even after high-temperature aging. The high-density network structure can block the penetration of moisture, heat, and oil, and the friction performance does not significantly decrease after being placed in a humid and hot environment. In terms of process, the resin has uniform particle size after treatment, making it easy to mix with other components; the curing parameters are mild and can be adapted to conventional brake pad production processes, requiring no extreme equipment, making costs controllable and easy to scale up for mass production.

[0065] Compared with the prior art, the present invention has the following advantages:

[0066] 1. Stable friction coefficient at high temperatures: The use of ceramic fiber, high-temperature resistant resin and heat-resistant friction modifier results in minimal attenuation of the friction coefficient in working environments of 400-600 ℃.

[0067] 2. Low wear rate and long service life: The metal fibers and graphite components play a role in dispersing heat, bearing part of the friction load, and reducing the shedding of abrasive particles. Through reasonable combination of fillers and reinforcing fibers, the strength and structural integrity of the material are improved.

[0068] 3. Good resistance to thermal cracking: Ceramic fibers and talc fibers and other heat-resistant fibers can effectively inhibit the propagation of cracks caused by thermal stress; the modification of resin binders improves its thermal stability.

[0069] 4. Low braking noise: Graphite and lubricants help form a stable friction surface film, reducing vibration and noise; rubber fibers / elastic components help buffer vibration and impact.

[0070] 5. Excellent environmental performance: Asbestos-free, low in heavy metals; uses non-toxic or low-toxic fillers and lubricants; reduces harmful substances in friction dust. Detailed Implementation

[0071] The features of the present invention are further illustrated below through embodiments, but the scope of protection of this patent is not limited to the embodiments.

[0072] Example 1

[0073] A method for preparing a high-performance semi-metallic composite brake pad includes the following steps, measured by mass:

[0074] a) Raw material preparation

[0075] Ceramic fiber: 8kg (alumina fiber), crushed to a length of 0.5mm;

[0076] Aramid fiber: 5 kg (DSM Kevlar®), pulverized to a length of 0.5 mm;

[0077] Inorganic fiber: 3kg (talc fiber);

[0078] Metal powder: 6 kg (copper fiber), dried to a moisture content of < 0.5%;

[0079] Friction modifier: 1 kg (molybdenum disulfide nanoparticles), particle size < 100 nm;

[0080] Graphite: 5kg (flake graphite);

[0081] Inert minerals: 15 kg (vermiculite);

[0082] Resin binder: 15kg;

[0083] b) Ingredients and Mixing

[0084] Weigh all the solid components according to the mass ratio and mix them together. Add 25 kg of isopropanol (an organic solvent, used as a medium and mixing agent), and put it into a ball mill and stir for 5 minutes to ensure that the components are evenly distributed.

[0085] c) Drying / Dehydration / Removal of Solvents

[0086] Preliminary drying: Place the mixture in a drying device and dry at 60°C for 1 hour;

[0087] Secondary drying: Heat to 120℃ and continue for 2 hours until the moisture content or residual solvent in the material is < 1 wt%.

[0088] d) Compression molding

[0089] The mixture after secondary drying is placed into a custom mold and molded under a pressure of 18MPa, with the molding temperature controlled at 80℃; the molding time is 2 minutes to allow the material to be initially shaped.

[0090] e) Laminated with a metal backing

[0091] A 2mm thick anti-corrosion steel plate is selected as the back plate. During the molding stage, the shaped material is laminated with the back plate. The lamination pressure is the same as the molding pressure, which is 18MPa.

[0092] f) Thermosetting / High-temperature sintering / Hot pressing curing

[0093] The laminated components are then placed into a hot press, and the temperature is set to 250℃ and the pressure to 15MPa. This state is maintained for 10 minutes to complete the thermosetting process.

[0094] g) Machining / Finishing

[0095] Burrs on the edges of the components are removed by special equipment and the friction surface is polished; no additional grooving or drilling is required according to the design requirements of the brake disc; the final friction surface roughness is controlled at Ra1.0μm.

[0096] The method for preparing the resin binder:

[0097] A1: By weight, add 40 kg of bisphenol A type epoxy resin (epoxy value 0.48-0.54 eq / 100g), 1.5 kg of epoxy succinic acid polymer (CAS No.: 51274-37-4), 0.5 kg of dimethyl 2-aminothiophene-3,4-dicarboxylate (CAS No.: 1520161-91-4), 5 kg of polyetheramine D230, 80 kg of ethylene glycol monomethyl ether, and 0.5 kg of triethanolamine to a reaction vessel; control the stirring rate at 300 rpm, raise the temperature to 60℃, and continue the reaction for 1.5 h;

[0098] A2: After the reaction is complete, the reaction solution is transferred to a rotary evaporator and distilled for 2 hours at a vacuum of 0.08-0.1 MPa and 80°C to remove all solvent. The resulting viscous resin is then transferred to a forced-air drying oven and dried at 120°C for 3 hours to form a solid resin block. Finally, the resin block is crushed by a jaw crusher, processed by an air jet mill, and passed through a 100-mesh sieve to obtain the resin binder.

[0099] Example 2

[0100] A method for preparing a high-performance semi-metallic composite brake pad includes the following steps, measured by mass:

[0101] a) Raw material preparation

[0102] Ceramic fiber: 10kg (mullite fiber), crushed to a length of 2mm;

[0103] Aramid fiber: 6.5kg (Kolon Twaron®), pulverized to a length of 2mm;

[0104] Inorganic fiber: 4kg (mica fiber);

[0105] Metal powder: 8 kg (copper alloy powder), dried to a moisture content of < 0.5%;

[0106] Friction modifier: 2.5 kg (zinc oxide nanoparticles), particle size < 100 nm;

[0107] Graphite: 6.5 kg (expanded graphite);

[0108] Inert minerals: 20 kg (mica);

[0109] Resin binder: 18kg;

[0110] b) Ingredients and Mixing

[0111] Weigh all the solid components according to the mass ratio and mix them together. Add 32 kg of ethanol (an organic solvent, used as a medium and mixing agent), and put it into a ball mill and stir for 10 minutes to ensure that the components are evenly distributed.

[0112] c) Drying / Dehydration / Removal of Solvents

[0113] Preliminary drying: Place the mixture in a drying device and dry at 75°C for 2 hours;

[0114] Secondary drying: Heat to 130℃ and continue for 3 hours until the moisture content or residual solvent in the material is < 1 wt%.

[0115] d) Compression molding

[0116] The mixture after secondary drying is placed into a custom mold and molded under a pressure of 24 MPa, with the molding temperature controlled at 95°C; the molding time is 5 minutes to allow the material to initially take shape.

[0117] e) Laminated with a metal backing

[0118] A 3mm thick galvanized steel sheet is selected as the backing plate. During the hot pressing stage, the shaped material is laminated with the backing plate. The lamination pressure is the same as the molding pressure, which is 24MPa.

[0119] f) Thermosetting / High-temperature sintering / Hot pressing curing

[0120] The laminated components are then placed into a hot press, and the temperature is set to 270℃ and the pressure to 20MPa. This setting is maintained for 18 minutes to complete the thermosetting process.

[0121] g) Machining / Finishing

[0122] Burrs on the edges of the components are removed using specialized equipment, and the friction surfaces are polished. Two positioning holes with a diameter of 8mm are machined according to the design requirements of the brake disc. The final surface roughness of the friction surface is controlled at Ra1.8μm.

[0123] The method for preparing the resin binder:

[0124] A1: By weight, add 48 kg of bisphenol A type epoxy resin (epoxy value 0.48-0.54 eq / 100g), 2 kg of epoxy succinic acid polymer (CAS No.: 51274-37-4), 1 kg of dimethyl 2-aminothiophene-3,4-dicarboxylate (CAS No.: 1520161-91-4), 8 kg of polyetheramine D230, 95 kg of ethylene glycol monomethyl ether, and 1 kg of triethanolamine to a reaction vessel; control the stirring rate at 380 rpm, raise the temperature to 63℃, and continue the reaction for 2 hours;

[0125] A2: After the reaction is complete, the reaction solution is transferred to a rotary evaporator and distilled for 3 hours at a vacuum of 0.08-0.1 MPa and 88°C to remove all solvent. The resulting viscous resin is then transferred to a forced-air drying oven and dried at 128°C for 4 hours to form a solid resin block. Finally, the resin block is crushed by a jaw crusher, processed by an air jet mill, and passed through a 140-mesh sieve to obtain the resin binder.

[0126] Example 3

[0127] A method for preparing a high-performance semi-metallic composite brake pad includes the following steps, measured by mass:

[0128] a) Raw material preparation

[0129] Ceramic fiber: 13kg (alumina fiber), crushed to a length of 4mm;

[0130] Aramid fiber: 8.5 kg (DSM Kevlar®), pulverized to a length of 4 mm;

[0131] Inorganic fiber: 5kg (calcium / magnesium silicate fiber);

[0132] Metal powder: 10 kg (copper fiber), dried to a moisture content of < 0.5%;

[0133] Friction modifier: 4 kg (chromium oxide nanoparticles), particle size < 100 nm;

[0134] Graphite: 8kg (flake graphite);

[0135] Inert minerals: 26 kg (barite);

[0136] Resin binder: 22kg;

[0137] b) Ingredients and Mixing

[0138] Weigh all the solid components according to the mass ratio and mix them together. Add 38 kg of isopropanol (an organic solvent, used as a medium and mixing agent), and put it into a ball mill and stir for 15 minutes to ensure that the components are evenly distributed.

[0139] c) Drying / Dehydration / Removal of Solvents

[0140] Preliminary drying: Place the mixture in a drying device and dry at 90°C for 2.5 hours;

[0141] Secondary drying: Heat to 140℃ and continue for 3.5 hours until the moisture content or residual solvent in the material is <1wt%;

[0142] d) Compression molding

[0143] The mixture after secondary drying is placed into a custom mold and molded under a pressure of 30MPa, with the molding temperature controlled at 110℃; the molding time is 8 minutes to allow the material to be initially shaped.

[0144] e) Laminated with a metal backing

[0145] A 4mm thick anti-corrosion steel plate is selected as the back plate. During the molding stage, the shaped material is laminated and bonded to the back plate. The bonding pressure is the same as the molding pressure, which is 30MPa.

[0146] f) Thermosetting / High-temperature sintering / Hot pressing curing

[0147] The laminated components are then placed into a hot press, and the temperature is set to 290℃ and the pressure to 26MPa. This state is maintained for 25 minutes to complete the thermosetting process.

[0148] g) Machining / Finishing

[0149] Burrs on the edges of the components are removed using specialized equipment, and the friction surface is polished. A heat dissipation groove with a width of 5mm and a depth of 3mm is machined according to the design requirements of the brake disc. The final surface roughness of the friction surface is controlled at Ra2.5μm.

[0150] The method for preparing the resin binder:

[0151] A1: By weight, add 55 kg of bisphenol A type epoxy resin (epoxy value 0.48-0.54 eq / 100g), 2.5 kg of epoxy succinic acid polymer (CAS No.: 51274-37-4), 1.5 kg of dimethyl 2-aminothiophene-3,4-dicarboxylate (CAS No.: 1520161-91-4), 12 kg of polyetheramine D230, 110 kg of ethylene glycol monomethyl ether, and 1.5 kg of triethanolamine to a reaction vessel; control the stirring rate at 450 rpm, raise the temperature to 67℃, and continue the reaction for 2.5 h;

[0152] A2: After the reaction is complete, the reaction solution is transferred to a rotary evaporator and distilled at a vacuum of 0.08-0.1 MPa and 95°C for 3.5 hours to remove all solvent. The resulting viscous resin is then transferred to a forced-air drying oven and dried at 135°C for 4.5 hours to form a solid resin block. Finally, the resin block is crushed by a jaw crusher, processed by an air jet mill, and passed through a 180-mesh sieve to obtain the resin binder.

[0153] Example 4

[0154] A method for preparing a high-performance semi-metallic composite brake pad includes the following steps, measured by mass:

[0155] a) Raw material preparation

[0156] Ceramic fiber: 15kg (mullite fiber), crushed to a length of 5mm;

[0157] Aramid fiber: 10kg (Kolon Twaron®), pulverized to a length of 5mm;

[0158] Inorganic fiber: 6kg (talc fiber);

[0159] Metal powder: 12kg (copper alloy powder), dried to a moisture content of < 0.5%;

[0160] Friction modifier: 5kg (iron oxide nanoparticles), particle size < 100nm;

[0161] Graphite: 9kg (expanded graphite);

[0162] Inert minerals: 30 kg (zirconium silicate);

[0163] Resin binder: 25kg;

[0164] b) Ingredients and Mixing

[0165] Weigh all the solid components according to the mass ratio and mix them together. Add 45 kg of ethanol (an organic solvent, used as a medium and mixing agent), and put it into a ball mill and stir for 20 minutes to ensure that the components are evenly distributed.

[0166] c) Drying / Dehydration / Removal of Solvents

[0167] Preliminary drying: Place the mixture in a drying device and dry at 100°C for 3 hours;

[0168] Secondary drying: Heat to 150℃ and continue for 4 hours until the moisture content or residual solvent in the material is < 1 wt%.

[0169] d) Compression molding

[0170] The mixture after secondary drying is placed into a custom mold and molded under a pressure of 35 MPa, with the molding temperature controlled at 120°C; the molding time is 10 minutes to allow the material to initially take shape.

[0171] e) Laminated with a metal backing

[0172] A 5mm thick galvanized steel sheet is selected as the backing plate. During the hot pressing stage, the shaped material is laminated with the backing plate. The lamination pressure is the same as the molding pressure, which is 35MPa.

[0173] f) Thermosetting / High-temperature sintering / Hot pressing curing

[0174] The laminated components are then placed into a hot press, and the temperature is set to 300℃ and the pressure to 30MPa. This state is maintained for 30 minutes to complete the thermosetting process.

[0175] g) Machining / Finishing

[0176] Burrs on the edges of the components are removed using specialized equipment, and the friction surface is polished. Three positioning holes with a diameter of 10mm and two heat dissipation grooves with a width of 6mm and a depth of 4mm are machined according to the design requirements of the brake disc. The final surface roughness of the friction surface is controlled at Ra3.0μm.

[0177] The method for preparing the resin binder:

[0178] A1: By weight, add 60 kg of bisphenol A type epoxy resin (epoxy value 0.48-0.54 eq / 100g), 3 kg of epoxy succinic acid polymer (CAS No.: 51274-37-4), 2 kg of dimethyl 2-aminothiophene-3,4-dicarboxylate (CAS No.: 1520161-91-4), 15 kg of polyetheramine D230, 120 kg of ethylene glycol monomethyl ether, and 2 kg of triethanolamine to a reaction vessel; control the stirring rate at 500 rpm, raise the temperature to 70℃, and continue the reaction for 3 hours;

[0179] A2: After the reaction is complete, the reaction solution is transferred to a rotary evaporator and distilled at a vacuum of 0.08-0.1 MPa and 100°C for 4 hours to remove all solvent. The resulting viscous resin is then transferred to a forced-air drying oven and dried at 140°C for 5 hours to form a solid resin block. Finally, the resin block is crushed by a jaw crusher, processed by an air jet mill, and passed through a 200-mesh sieve to obtain the resin binder.

[0180] Comparative Example 1

[0181] A method for preparing a high-performance semi-metallic composite brake pad includes the following steps, measured by mass:

[0182] a) Raw material preparation

[0183] Ceramic fiber: 8kg (alumina fiber), crushed to a length of 0.5mm;

[0184] Aramid fiber: 5 kg (DSM Kevlar®), pulverized to a length of 0.5 mm;

[0185] Inorganic fiber: 3kg (talc fiber);

[0186] Metal powder: 6 kg (copper fiber), dried to a moisture content of < 0.5%;

[0187] Friction modifier: 1 kg (molybdenum disulfide nanoparticles), particle size < 100 nm;

[0188] Graphite: 5kg (flake graphite);

[0189] Inert minerals: 15 kg (vermiculite);

[0190] Resin binder: 15kg;

[0191] b) Ingredients and Mixing

[0192] Weigh all the solid components according to the mass ratio and mix them together. Add 25 kg of isopropanol (an organic solvent, used as a medium and mixing agent), and put it into a ball mill and stir for 5 minutes to ensure that the components are evenly distributed.

[0193] c) Drying / Dehydration / Removal of Solvents

[0194] Preliminary drying: Place the mixture in a drying device and dry at 60°C for 1 hour;

[0195] Secondary drying: Heat to 120℃ and continue for 2 hours until the moisture content or residual solvent in the material is < 1 wt%.

[0196] d) Compression molding

[0197] The mixture after secondary drying is placed into a custom mold and molded under a pressure of 18MPa, with the molding temperature controlled at 80℃; the molding time is 2 minutes to allow the material to be initially shaped.

[0198] e) Laminated with a metal backing

[0199] A 2mm thick anti-corrosion steel plate is selected as the back plate. During the molding stage, the shaped material is laminated with the back plate. The lamination pressure is the same as the molding pressure, which is 18MPa.

[0200] f) Thermosetting / High-temperature sintering / Hot pressing curing

[0201] The laminated components are then placed into a hot press, and the temperature is set to 250℃ and the pressure to 15MPa. This state is maintained for 10 minutes to complete the thermosetting process.

[0202] g) Machining / Finishing

[0203] Burrs on the edges of the components are removed by special equipment and the friction surface is polished; no additional grooving or drilling is required according to the design requirements of the brake disc; the final friction surface roughness is controlled at Ra1.0μm.

[0204] The method for preparing the resin binder:

[0205] A1: By weight, add 40 kg of bisphenol A type epoxy resin (epoxy value 0.48-0.54 eq / 100g), 1.5 kg of epoxy succinic acid polymer (CAS No.: 51274-37-4), 5 kg of polyetheramine D230, 80 kg of ethylene glycol monomethyl ether, and 0.5 kg of triethanolamine to the reactor; control the stirring rate at 300 rpm, raise the temperature to 60℃, and continue the reaction for 1.5 h;

[0206] A2: After the reaction is complete, the reaction solution is transferred to a rotary evaporator and distilled for 2 hours at a vacuum of 0.08-0.1 MPa and 80°C to remove all solvent. The resulting viscous resin is then transferred to a forced-air drying oven and dried at 120°C for 3 hours to form a solid resin block. Finally, the resin block is crushed by a jaw crusher, processed by an air jet mill, and passed through a 100-mesh sieve to obtain the resin binder.

[0207] Comparative Example 2

[0208] A method for preparing a high-performance semi-metallic composite brake pad includes the following steps, measured by mass:

[0209] a) Raw material preparation

[0210] Ceramic fiber: 8kg (alumina fiber), crushed to a length of 0.5mm;

[0211] Aramid fiber: 5 kg (DSM Kevlar®), pulverized to a length of 0.5 mm;

[0212] Inorganic fiber: 3kg (talc fiber);

[0213] Metal powder: 6 kg (copper fiber), dried to a moisture content of < 0.5%;

[0214] Friction modifier: 1 kg (molybdenum disulfide nanoparticles), particle size < 100 nm;

[0215] Graphite: 5kg (flake graphite);

[0216] Inert minerals: 15 kg (vermiculite);

[0217] Resin binder: 15kg;

[0218] b) Ingredients and Mixing

[0219] Weigh all the solid components according to the mass ratio and mix them together. Add 25 kg of isopropanol (an organic solvent, used as a medium and mixing agent), and put it into a ball mill and stir for 5 minutes to ensure that the components are evenly distributed.

[0220] c) Drying / Dehydration / Removal of Solvents

[0221] Preliminary drying: Place the mixture in a drying device and dry at 60°C for 1 hour;

[0222] Secondary drying: Heat to 120℃ and continue for 2 hours until the moisture content or residual solvent in the material is < 1 wt%.

[0223] d) Compression molding

[0224] The mixture after secondary drying is placed into a custom mold and molded under a pressure of 18MPa, with the molding temperature controlled at 80℃; the molding time is 2 minutes to allow the material to be initially shaped.

[0225] e) Laminated with a metal backing

[0226] A 2mm thick anti-corrosion steel plate is selected as the back plate. During the molding stage, the shaped material is laminated with the back plate. The lamination pressure is the same as the molding pressure, which is 18MPa.

[0227] f) Thermosetting / High-temperature sintering / Hot pressing curing

[0228] The laminated components are then placed into a hot press, and the temperature is set to 250℃ and the pressure to 15MPa. This state is maintained for 10 minutes to complete the thermosetting process.

[0229] g) Machining / Finishing

[0230] Burrs on the edges of the components are removed by special equipment and the friction surface is polished; no additional grooving or drilling is required according to the design requirements of the brake disc; the final friction surface roughness is controlled at Ra1.0μm.

[0231] The method for preparing the resin binder:

[0232] A1: By weight, add 40 kg of bisphenol A type epoxy resin (epoxy value 0.48-0.54 eq / 100g), 0.5 kg of dimethyl 2-aminothiophene-3,4-dicarboxylate (CAS No.: 1520161-91-4), 5 kg of polyetheramine D230, 80 kg of ethylene glycol monomethyl ether, and 0.5 kg of triethanolamine to a reaction vessel; control the stirring rate at 300 rpm, raise the temperature to 60℃, and continue the reaction for 1.5 h;

[0233] A2: After the reaction is complete, the reaction solution is transferred to a rotary evaporator and distilled for 2 hours at a vacuum of 0.08-0.1 MPa and 80°C to remove all solvent. The resulting viscous resin is then transferred to a forced-air drying oven and dried at 120°C for 3 hours to form a solid resin block. Finally, the resin block is crushed by a jaw crusher, processed by an air jet mill, and passed through a 100-mesh sieve to obtain the resin binder.

[0234] Test methods and results:

[0235] 1. Static / Initial Friction Coefficient and Thermal Fade Test – Based on SAE J661 / J2707 Principle

[0236] Objective: To determine the coefficient of friction at room temperature and high temperature, and to calculate the percentage of thermal decay.

[0237] Instrumentation: Inertial / electro-electric friction material testing bench (Greening Model 1050), equipped with a standard cast iron / steel rotor.

[0238] Test conditions:

[0239] Contact surface pressure (average contact pressure): 1.0 ± 0.05 MPa.

[0240] Relative sliding speed: 12 m / s.

[0241] Environment: Dry, room temperature (25 ± 3 ℃) COF was measured at room temperature; then heated according to the thermal decay program.

[0242] Thermal decay procedure:

[0243] a. Static measurement at room temperature: Run 10 cycles and record the average friction coefficient μ0 (25 ℃) during the steady-state period.

[0244] b. Continuous braking heating to high temperature (control the rotor surface temperature or friction interface temperature to 400 ℃ ± 10℃, the heating rate and energy are set according to the test bench to achieve the target temperature).

[0245] c. Repeat the same operating conditions at 400 ℃ and record the high-temperature stable friction coefficient μ_h.

[0246] d. Calculate the fade rate (fade %) = (μ_h − μ0) / μ0 ×100%.

[0247] Test repeatability: Perform at least 3 independent test cases (n=3) for each sample and provide the mean and standard deviation.

[0248] Table 1. Test results of coefficient of friction (COF) and thermal fade.

[0249] Room temperature COF (25 °C) High temperature COF (400 °C) Degradation rate Example 1 0.36 0.33 -10.5 Example 2 0.38 0.33 -10.1 Example 3 0.39 0.34 -9.8 Example 4 0.39 0.34 -9.6 Comparative Example 1 0.35 0.32 -11.0 Comparative Example 2 0.34 0.32 -11.8

[0250] 2. Wear Rate Test – Based on SAE J2707 (or J2986 Thickness / Mass Measurement Rules)

[0251] Objective: To measure the mass or volume loss of a friction material under a given cycle or energy.

[0252] step:

[0253] Contact pressure: 1.0 MPa; speed: 12 m / s; number of cycles: 1000.

[0254] Measurements were taken at both room temperature and high temperature (400 ℃): the sample was weighed before and after each test segment (balance accuracy 0.1mg) and the thickness change was measured (micrometer / thickness gauge).

[0255] Record the wear amount (mg / 1000 times) or volumetric wear (mm³ / km, converted to density).

[0256] For each sample, n=3, the mean and standard deviation are given.

[0257] Table 2 Wear Rate Test Results

[0258] Room temperature wear (mg / 1000) High temperature wear (400 °C, mg / 1000) Example 1 46 61 Example 2 44 59 Example 3 44 58 Example 4 42 55 Comparative Example 1 48 64 Comparative Example 2 51 67

[0259] 3. Bond / Shear strength test — Refer to ISO 6312 / GB / T 22309

[0260] Objective: To determine the bond strength (shear strength) between the friction layer and the backing plate and to assess the risk of interlayer failure.

[0261] Key steps:

[0262] The specimens are cut according to the standard or used as complete components; the specimens are heated to the specified temperature (300 ℃ ± 10 ℃ is commonly used for disc brake pads), maintained for 60 s, and then sheared on the shear fixture; the force required for shear failure is recorded and the shear strength (MPa) is calculated.

[0263] Test at least 5 samples (or as required by the standard) and record the mean and minimum values.

[0264] Table 3 Bond / shear strength test results

[0265] Shear strength (MPa, 300 °C test) Example 1 3.25 Example 2 3.33 Example 3 3.39 Example 4 3.43 Comparative Example 1 3.14 Comparative Example 2 3.07

[0266] As can be seen from the above specific implementation scheme, the brake pads prepared by this method have improved in terms of high-temperature stability, wear resistance, and interfacial adhesion, revealing the superiority of the present invention.

[0267] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention. Any aspects not detailed in the present invention are well-known techniques to those skilled in the art.

Claims

1. A method for preparing a high-performance semi-metallic composite brake pad, characterized in that, Includes the following steps, measured in parts by weight: a) Raw materials Ceramic fiber: 8-15 parts, crushed to a length of 0.5-5 mm; Aramid fiber: 5-10 parts, crushed to a length of 0.5-5 mm; Inorganic fibers: 3-6 parts; Metal powder: 6-12 parts, dried to a moisture content of < 0.5%; Friction modifier: 1-5 parts, particle size < 100 nm; Graphite: 5-9 parts, flake graphite or expanded graphite; Inert minerals: 15-30 parts; Resin binder: 15-25 parts; b) Ingredients and Mixing Weigh and mix all solid components according to the above proportions, add 25-45 parts of organic solvent as a medium mixing agent, and mix by ball milling for 5-20 minutes to ensure uniform distribution of components; c) Drying / Dehydration / Removal of Solvents Preliminary drying: 60-100 ℃, for 1-3 hours; Secondary drying: 120-150 ℃, 2-4 hours, until the moisture content or residual solvent is < 1 wt%; d) Compression molding The dried mixture is placed into a mold and molded under a pressure of 18-35 MPa and a temperature of 80-120 ℃ for 2-10 minutes to achieve initial shaping. e) Laminated with a metal backing The backing plate is made of corrosion-resistant steel plate or galvanized steel plate, with a thickness of 2-5 mm; it can be laminated during molding or hot pressing; the lamination pressure is the same as the molding pressure. f) Thermosetting / High-temperature sintering / Hot pressing curing Temperature range: 250-300 ℃; Pressure range 15-30 MPa; Keep it on for 10-30 minutes; g) Machining / Finishing Remove burrs, grind the surface, and if grooving or drilling is required, the groove depth and hole diameter shall be determined according to the brake disc design requirements; the final friction surface roughness shall be controlled within Ra 1.0-3.0 µm; The resin binder is prepared by reacting bisphenol A type epoxy resin, epoxy succinic acid polymer, dimethyl 2-aminothiophene-3,4-dicarboxylate, polyetheramine D230, ethylene glycol monomethyl ether, and triethanolamine.

2. The method for preparing a high-performance semi-metallic composite brake pad according to claim 1, characterized in that: The ceramic fiber is selected from alumina fiber or mullite fiber.

3. The method for preparing a high-performance semi-metallic composite brake pad according to claim 1, characterized in that: The aramid fiber is a commercially available Aramid® polymer fiber, selected from DSM Kevlar or Kolon Twaron.

4. The method for preparing a high-performance semi-metallic composite brake pad according to claim 1, characterized in that: The inorganic fibers are selected from talc fibers, mica fibers, or calcium / magnesium silicate fibers.

5. The method for preparing a high-performance semi-metallic composite brake pad according to claim 1, characterized in that: The metal powder is selected from copper fiber or copper alloy powder.

6. The method for preparing a high-performance semi-metallic composite brake pad according to claim 1, characterized in that: The friction modifier nanoparticles are selected from one or more of molybdenum disulfide, zinc oxide, chromium oxide, and iron oxide nanoparticles.

7. The method for preparing a high-performance semi-metallic composite brake pad according to claim 1, characterized in that: The inert mineral is selected from one or more of vermiculite, mica, talc, barite, zirconium silicate, and potassium feldspar.

8. The method for preparing a high-performance semi-metallic composite brake pad according to claim 1, characterized in that: The method for preparing the resin binder: A1: According to the mass fractions, add 40-60 parts of bisphenol A type epoxy resin with an epoxy value of 0.48-0.54 eq / 100g, 1.5-3 parts of epoxy succinic acid polymer, 0.5-2 parts of dimethyl 2-aminothiophene-3,4-dicarboxylate, 5-15 parts of polyetheramine D230, 80-120 parts of ethylene glycol monomethyl ether, and 0.5-2 parts of triethanolamine to a reaction vessel, control the stirring speed at 300-500 rpm, and react at 60-70℃ for 1.5-3 hours; A2: After the reaction is complete, the reaction solution is transferred to a rotary evaporator and distilled at a vacuum of 0.08-0.1 MPa and 80-100℃ for 2-4 hours to remove all solvent. Then, the viscous resin is transferred to a forced-air drying oven and dried at 120-140℃ for 3-5 hours to form a solid resin block. Finally, the resin block is crushed with a jaw crusher, processed by an air jet mill, and passed through a 100-200 mesh sieve to obtain the resin binder.

9. The method for preparing a high-performance semi-metallic composite brake pad according to claim 1, characterized in that: The organic solvent is selected from isopropanol or ethanol.