Triangular sheet-shaped laco3oh reinforced benzoxazine resin-based composite friction material, and preparation method and application thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NORTHWESTERN POLYTECHNICAL UNIV
- Filing Date
- 2026-04-27
- Publication Date
- 2026-06-23
AI Technical Summary
Existing friction materials lack thermal stability under high temperature and high load conditions, have unstable friction coefficients, and suffer severe wear, making it difficult to meet the high-efficiency braking requirements of heavy-duty equipment.
A benzoxazine resin-based composite friction material reinforced with triangular-shaped LaCO3OH is used. By introducing triangular-shaped LaCO3OH filler and benzoxazine resin as organic binders and combining them with a hot-press curing process, a layered structure is formed, which improves the material's load-bearing capacity and frictional stability.
The material's compressive strength is increased by 20.2%~44.8%, wear rate is reduced by 68%~81%, and the friction coefficient is less sensitive to pressure changes, making it suitable for high loads and complex braking conditions.
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Figure CN122255656A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of friction material technology, specifically relating to a triangular-plate-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material, its preparation method, and its application. Background Technology
[0002] Brake pads, as a core safety component in automotive, aircraft, and industrial braking systems, function to convert kinetic energy into heat energy through friction, thereby achieving deceleration and stopping, and ensuring the safe operation of equipment. With the development of modern transportation and industrial equipment towards high speed and heavy load, higher demands are placed on the comprehensive performance of braking materials. Among these, a stable coefficient of friction and low wear characteristics are crucial for ensuring their service life and safety. Although resin-based friction materials dominate the market due to their good processability and overall cost advantages, the widely used traditional phenolic resin bonding system still has significant application limitations, especially its insufficient thermal stability under harsh conditions such as high temperature and high load, which seriously restricts its reliability and service life. Under extreme braking conditions, the friction surface temperature exceeds 300 ℃, causing significant thermal decomposition of the phenolic resin, leading to chain segment breakage, cross-linked structure collapse, and even carbonization and volatilization. This microscale structural damage directly triggers interfacial adhesion failure and friction film instability, resulting in decreased braking performance and increased braking distance. In addition, its processing has inherent defects. Phenolic resin is cured through condensation reaction, releasing harmful volatile substances such as formaldehyde and phenol. This not only poses a threat to the production environment and the health of operators, but also increases the environmental pressure of subsequent waste gas treatment.
[0003] Chinese invention patent application CN108410042A discloses "a synthetic friction material suitable for high braking energy," which uses carboxylated nitrile rubber-nanomontmorillonite modified phenolic resin as a binder, and incorporates iron sulfide, diatomaceous earth, steel fibers, and nano-precipitated barium silicate, and is prepared through plasticizing, internal mixing, hot pressing, and heat treatment. When the braking speed changes from 20 km / h to 120 km / h, the friction coefficient of this invention significantly decreases from 0.39 to 0.28, and the wear rate is between 0.21 and 0.34 cm. 3Its coefficient of friction fluctuates within the range of / MJ, but its compressive strength is only 38 MPa, which is insufficient for pressure resistance and makes it difficult to apply under harsh braking conditions. Another Chinese invention patent application, CN119101323A, discloses "a phenolic resin-based composite material suitable for harsh dry friction conditions." This invention uses thermosetting phenolic resin as the matrix, adds reinforcing fibers such as carbon fiber and silicate nanofillers functionalized with silane coupling agents, and obtains the composite material through plasticizing, crushing, electron beam radiation crosslinking, three-stage molding, and long-term heat treatment. Although this invention exhibits a low wear rate under dry friction conditions of 2 MPa and 1.5 m / s, its coefficient of friction is only 0.08~0.25, which is difficult to meet the requirements of high and stable coefficient of friction and low wear under harsh conditions. At the same time, the preparation cycle exceeds 15 hours, which is not conducive to industrial production. Currently, existing friction pads on the market are still mainly based on the traditional resin-fiber-filler system. Limited by the inherent processing characteristics and poor high-temperature resistance of the traditional phenolic resin binder system, they generally suffer from insufficient compressive strength, large fluctuations in the coefficient of friction, and severe wear under the triple coupling conditions of "higher pressure, higher temperature, and higher energy density." Most products exhibit significant fluctuations in friction performance under harsh conditions, making them unsuitable for high-pressure, heavy-load applications such as heavy-duty freight transport and the clutch operation of construction machinery.
[0004] Therefore, there is an urgent need to develop a new type of friction material with a stable coefficient of friction and high wear resistance over a wide pressure range, so as to combine high compressive strength with excellent friction and wear performance, in order to meet the long service life and high reliability braking requirements of high-end equipment under extreme working conditions, and ensure the safe and efficient operation of heavy-duty equipment. Summary of the Invention
[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a triangular sheet-like LaCO3OH-reinforced benzoxazine resin-based composite friction material, its preparation method and application, which has both high compressive strength and excellent tribological properties.
[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention provides a triangular-plate-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material, comprising, by weight percentage, 20%... 30% organic binder, 20% fiber-reinforced phase, and 50%... 60% inorganic filler; The organic binder is a benzoxazine resin; The inorganic filler is one or more of the following: calcium sulfate, barium sulfate, alumina, calcium carbonate, zirconium oxide, chromite, diamond powder, silicon dioxide, graphite, molybdenum disulfide, tungsten disulfide, diatomite, vermiculite, kaolin, and carbon black, and contains at least 5% triangular laco3OH; wherein the triangular laco3OH exhibits a regular triangular morphology, with straight edges, a smooth surface, and a side length of 6~7 μm.
[0007] In one embodiment, the benzoxazine resin is one or more of the following: bisphenol A type benzoxazine resin, bisphenol F type benzoxazine resin, phenolphthalein type benzoxazine resin, dicyclopentadiene type benzoxazine resin, phosphorus-containing benzoxazine resin, and diamine type benzoxazine resin; The fiber reinforcement phase is one or more of polyacrylonitrile-based carbon fiber, pitch-based carbon fiber, aramid fiber, mineral fiber, basalt fiber, glass fiber and steel fiber; wherein, the polyacrylonitrile-based carbon fiber and the pitch-based carbon fiber are both short-cut carbon fibers with a length of 40~100 μm and a diameter of 8~20 μm.
[0008] In one embodiment, the triangular sheet-like LaCO3OH is dispersed in the matrix and locally forms an ordered stacked structure, with the sheet-like fillers forming a layered arrangement structure through overlapping and contact.
[0009] In one embodiment, the method for preparing the triangular sheet-like LaCO3OH includes the following steps: S1: Dissolve lanthanum chloride hexahydrate in deionized water by stirring to obtain a precursor solution; S2: Under stirring conditions, concentrated ammonia is added dropwise to the precursor solution to adjust the pH of the system. Then urea is added, stirred to dissolve, and then the volume is adjusted to obtain the reaction solution. S3: The reaction solution is placed in a hydrothermal reactor to react and obtain a reaction mixture; S4: The reaction mixture is naturally cooled to room temperature, and after solid-liquid separation, it is washed several times with deionized water and anhydrous ethanol, and then vacuum dried to obtain triangular sheet-like LaCO3OH.
[0010] In one embodiment, in S1, La in the precursor solution 3+ The concentration is 0.03~0.05 mol / L; In S2, the concentrated ammonia solution has a mass fraction of 25%~28%, and the system pH is 8.0~9.0; the amount of urea added is La. 3+ Four times the molar amount; In S3, the filling degree of the reaction liquid in the hydrothermal reactor is 70%~80%, the reaction temperature is 130℃, and the time is 8h.
[0011] In one embodiment, under a pressure of 0.5-5 MPa, the coefficient of friction of the triangular LaCO3OH-reinforced benzoxazine resin-based composite friction material is 0.20-0.35, and the volumetric wear rate is 0.0105-0.0414 cm. 3 / MJ.
[0012] This invention also provides a method for preparing a triangular sheet-like LaCO3OH-reinforced benzoxazine resin-based composite friction material, comprising the following steps: A fiber-reinforced phase is prepared by mixing the fiber-reinforced phase, organic binder, and inorganic filler to obtain a mixed powder. The mixed powder is loaded into a mold and hot-pressed for curing. After demolding, a preform is obtained. The preform is heat-treated, then cooled to room temperature, and then machined to obtain a triangular-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material.
[0013] In one embodiment, during the preparation of the fiber reinforcing phase, the mixing is carried out at a speed of 8000 rpm to 12000 rpm, the mixing time for each mixing is 2 s to 5 s, the interval between each mixing is 3 min to 6 min, and the mixing is repeated 3 times. The mixing speed is 8000 rpm to 12000 rpm, the mixing time for a single mixing is 2 s to 5 s, the interval between each mixing is 3 min to 6 min, and the mixing is repeated 3 times.
[0014] In one embodiment, the hot-press curing conditions are as follows: temperature is 150 ℃~220 ℃, pressure is 8 MPa~15 MPa, and time is 600 s~1000 s; The heat treatment conditions are as follows: the treatment temperature is 150 ℃~220 ℃, and the holding time is 100 min~150 min.
[0015] The present invention also provides the application of a triangular sheet-like LaCO3OH-reinforced benzoxazine resin-based composite friction material in brake pads.
[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a benzoxazine resin-based composite friction material reinforced with triangular-plate-shaped LaCO3OH, using benzoxazine resin instead of traditional phenolic resin as the organic binder. Because benzoxazine resin releases fewer small-molecule byproducts and exhibits less curing shrinkage during hot-pressing, it helps reduce the formation of internal pores, cracks, and interface defects, resulting in a denser and more uniform material structure. Furthermore, this resin system requires no additional venting during hot-pressing and can be cured in a single heating cycle, simplifying the preparation process and improving production efficiency. Compared to traditional phenolic resin systems, benzoxazine resin also possesses better thermal stability and interfacial bonding ability, improving the material's mechanical properties and structural stability under high-temperature conditions. By introducing triangular-plate-shaped LaCO3OH filler, the material's load-bearing capacity, frictional stability, and wear resistance are further improved, making the resulting composite friction material more suitable for high-load and complex braking conditions.
[0017] Furthermore, this invention synthesizes a triangular laCO3OH filler with a specific microstructure. The filler is in the form of truncated triangular plates with straight edges and a smooth, flat surface. The plate side length is 6-7 μm. It is dispersed in the matrix and locally forms an ordered stacked structure. The plates overlap and contact to form a layered arrangement. Due to its micron-sized plates, the filler can achieve a relatively uniform distribution in the resin matrix and reduce agglomeration caused by excessively small particle size. During friction, the triangular laCO3OH filler and its fragments can embed into the friction interface, participating in the construction of the friction film through mutual contact and mechanical interlocking, forming a continuous film structure on the friction surface, thereby reducing direct contact between friction pairs. Through these structural features, the fluctuation of the friction coefficient with pressure can be reduced, improving the frictional stability and wear resistance of the material under high-pressure conditions.
[0018] In summary, this invention optimizes the binder system, inorganic filler, and hot pressing process to prepare a benzoxazine resin-based friction material. Compared with existing technologies, this material exhibits an increase in compressive strength of approximately 20.2% to 44.8%, a reduction in wear rate of approximately 68% to 81%, and a decrease in the sensitivity of the dynamic friction coefficient to pressure changes. This addresses the problems of insufficient compressive strength, significant wear, and poor frictional stability in existing friction materials under high-pressure conditions. Attached Figure Description
[0019] Figure 1 Thermogravimetric analysis curves of the organic binders used in various embodiments of the present invention in the range of room temperature to 800 °C; Figure 2 SEM and EDS images of triangular sheet-like LaCO3OH prepared by hydrothermal method; Figure 3The XRD pattern of the prepared LaCO3OH and the corresponding standard PDF card are shown. Figure 4 The room temperature mechanical results of the resin-based friction materials prepared in Examples 1-3 and Comparative Examples 1-4 of this invention are shown in Figure (a), which shows the compressive strength, and Figure (b), which shows the shear strength. Figure 5 The friction coefficient of the resin-based friction materials prepared in Examples 1-3 and Comparative Examples 1-4 of this invention varies within a braking pressure range of 0.5 MPa to 5 MPa. Figure 6 The results show the volumetric wear rate of the resin-based friction materials prepared in Examples 1-3 and Comparative Example 1 of this invention under braking pressures ranging from 0.5 MPa to 5 MPa. Detailed Implementation
[0020] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.
[0021] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.
[0022] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values (including integers and fractions) within those ranges.
[0023] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”
[0024] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.
[0025] This invention provides a triangular-plate-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material, its preparation method, and its application. This method, through innovative selection of the binder system and synergistic design of components and processes, aims to ensure the material's high wear resistance while significantly improving its frictional stability and thermal load-bearing capacity under high braking pressure, thereby extending the service life of brake pads under harsh working conditions.
[0026] On the one hand, a triangular-plate-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material is provided, which, by weight, includes the following raw materials: 20-30 parts of organic binder, 20 parts of fiber reinforcing phase and 50-60 parts of inorganic filler.
[0027] The organic binder is a benzoxazine resin; wherein the benzoxazine resin is one or more of the following: bisphenol A type benzoxazine resin, bisphenol F type benzoxazine resin, phenolphthalein type benzoxazine resin, dicyclopentadiene type benzoxazine resin, phosphorus-containing benzoxazine resin, and diamine type benzoxazine resin.
[0028] The fiber reinforcement phase is one or more of polyacrylonitrile-based carbon fiber, pitch-based carbon fiber, aramid fiber, mineral fiber, basalt fiber, glass fiber and steel fiber; wherein, the polyacrylonitrile-based carbon fiber and the pitch-based carbon fiber are both short-cut carbon fibers with a length of 40~100 μm and a diameter of 8~20 μm.
[0029] The combined mass ratio of polyacrylonitrile-based carbon fiber to aramid fiber is 16%.
[0030] The inorganic filler is one or more of calcium sulfate, barium sulfate, alumina, calcium carbonate, zirconium oxide, chromite, diamond powder, silicon dioxide, graphite, molybdenum disulfide, tungsten disulfide, diatomite, vermiculite, kaolin, and carbon black, and contains at least 5% triangular laco3OH; wherein the triangular laco3OH exhibits a regular triangular morphology, with straight edges, smooth surface, and a side length of 6~7 μm, and is dispersed in the matrix and locally forms an ordered stacked structure, with the lacops forming a layered arrangement structure through overlap and contact.
[0031] The preparation method of the triangular plate-shaped LaCO3OH includes the following steps: (1) Dissolve lanthanum chloride hexahydrate in deionized water and stir until completely dissolved to obtain a precursor solution; the precursor solution contains La 3+ The concentration is 0.03~0.05 mol / L; (2) Under stirring conditions, concentrated ammonia is added dropwise to the precursor solution to adjust the pH of the system to 8.0~9.0, then urea is added, stirred to dissolve, and then brought to a final volume to obtain the reaction solution; the mass fraction of the concentrated ammonia in step (2) is 25%~28%, and the amount of urea added is La 3+ Four times the molar amount; (3) The reaction solution was placed in a hydrothermal reactor lined with polytetrafluoroethylene, with a filling degree of 70%~80%, and reacted at 130℃ for 8 h to obtain the reaction mixture; (4) The reaction mixture was naturally cooled to room temperature, and after solid-liquid separation, it was washed three times with deionized water and anhydrous ethanol respectively, and then dried under vacuum at 60 °C for 12 h to obtain triangular LaCO3OH.
[0032] More preferably, the inorganic filler contains self-synthesized triangular la3OH, which has a regular triangular plate structure with a side length of 6-7 μm. Its unique two-dimensional plate morphology is oriented in the resin matrix, which can form a continuous and stable solid lubrication transfer film at the friction interface, effectively isolating the friction pairs from direct contact and uniformly distributing contact stress, thereby significantly suppressing wear aggravation and friction coefficient fluctuations under high pressure.
[0033] Under braking pressures of 0.5-5 MPa, the coefficient of friction of the triangular-plate-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material is 0.21-0.31, and the volumetric wear rate is 0.0105-0.0414 cm. 3 / MJ.
[0034] One aspect provides a method for preparing a triangular-plate-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material, comprising the following steps: Step 1: Mixing Steps The fiber-reinforcing phase, organic binder, and inorganic filler are mixed in stages to obtain a mixed powder. 1) Prepare the fiber-reinforcing phase. Fiber premixing: The mixing speed is 8000~12000 rpm, the mixing time is 2~5 seconds, the interval time is 3~6 minutes, and the mixing is carried out 3 times in total to obtain the fiber-reinforcing phase. 2) Powder mixing: Add the organic binder, inorganic filler and fiber reinforcement phase into a high-speed mixer. The mixing speed is 8000~12000 rpm, the mixing time is 2~5 seconds, the interval is 3~6 minutes, and the mixing is repeated 3 times in total to obtain mixed powder.
[0035] Step 2: Hot pressing molding step: The mixed powder obtained in step one is loaded into a mold and hot-pressed for curing. After demolding, a preform is obtained. Hot pressing curing meets the following conditions: temperature 150~220 ℃, pressure 8~15 MPa, time 600~1000s; and no pressure relief or venting is required during the entire hot pressing process.
[0036] Step 3: Secondary heat treatment steps: The preform obtained in step two was heat-treated, then cooled to room temperature, and then machined to obtain a triangular-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material.
[0037] The heat treatment adopts a single-stage heat treatment process: the treatment temperature is 150 ℃~220 ℃, and the holding time is 100 minutes~150 minutes.
[0038] On the other hand, the application of the above-mentioned triangular LaCO3OH reinforced benzoxazine resin-based composite friction material under high pressure conditions is also provided.
[0039] The material preparation adopts a hot pressing molding combined with a secondary heat treatment process. Through the synergistic optimization of components and processes, the inherent defects of traditional phenolic resins, such as curing volatilization and poor high-temperature stability, are effectively overcome.
[0040] Test results show that the compressive strength of the material of the present invention is 20.2-44.8% higher than that of traditional phenolic resin-based friction materials; within the pressure range of 0.5-5 MPa, the sensitivity of the friction coefficient to pressure is significantly reduced, and the wear rate is reduced by about 68-81%.
[0041] Furthermore, by introducing a triangular lacoil-shaped LaCO3OH filler into the resin system, this invention achieves synergistic optimization of mechanical properties and tribological properties under high-pressure braking conditions, exhibiting significant advantages such as high performance, long service life, and environmental friendliness.
[0042] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.
[0043] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.
[0044] Comparative Example 1: A method for preparing a traditional phenolic resin-based friction material includes the following steps: Step 1: Prepare the mixed powder: Add 10% by mass of polyacrylonitrile-based carbon fiber, 4% by mass of pitch-based carbon fiber, and 6% by mass of aramid fiber into a high-speed mixer. Set the speed to 10,000 rpm, and stir for 3 seconds followed by 5 minutes of resting. Repeat this operation 3 times. Then, add 30% by mass of phenolic resin and 50% by mass of composite filler to the above mixed fibers. The composite filler consists of 10% calcium sulfate, 10% barium sulfate, 5% alumina, 7% calcium carbonate, 10% diatomaceous earth, 5% graphite, 2% molybdenum disulfide, and 1% carbon black. Continue mixing at 10,000 rpm, and repeat the cycle of stirring for 3 seconds and resting for 5 minutes 3 times to obtain a uniform mixed powder.
[0045] Step 2, hot pressing: Take an appropriate amount of the mixed powder and fill it into the preset mold. Set the hot pressing temperature to 160℃, the molding pressure to 10 MPa, and the pressing time to 900 seconds. During the pressing process, release the air once every 40 seconds for 2 seconds. Repeat the operation 8 times. After the material has completely solidified, demold to obtain the preform.
[0046] Step 3, preparation of friction material: The preform is placed in an oven for heat treatment, heated to 160°C and held for 150 minutes; then heated to 190°C and held for 180 minutes. After completion, it is naturally cooled to room temperature, and the burrs are removed by machining to obtain phenolic resin-based friction material.
[0047] Comparative Example 2: A method for preparing a benzoxazine resin-based composite friction material includes the following steps: Step 1: Preparation of mixed powder: 10% polyacrylonitrile-based carbon fiber, 4% pitch-based carbon fiber, and 6% aramid fiber by mass are added to a high-speed mixer. The speed is set to 10,000 rpm. After stirring for 3 seconds each time, the mixture is allowed to stand for 5 minutes. This operation is repeated 3 times. Subsequently, 30% bisphenol A type benzoxazine resin and 50% composite filler by mass are added to the above mixed fibers. The composite filler consists of 10% calcium sulfate, 10% barium sulfate, 5% alumina, 7% calcium carbonate, 10% diatomaceous earth, 5% graphite, 2% molybdenum disulfide, and 1% carbon black. Mixing is continued at 10,000 rpm. The same cycle of stirring for 3 seconds and standing for 5 minutes is repeated 3 times to obtain a uniform mixed powder.
[0048] Step 2, hot pressing: Take an appropriate amount of the mixed powder and fill it into the preset mold. Set the hot pressing temperature to 200℃, the molding pressure to 10 MPa, and the pressing time to 900 seconds. No venting is required during the pressing process. After the material has completely solidified, demold to obtain the preform.
[0049] Step 3, preparation of friction material: The preform is placed in an oven for heat treatment, heated to 205 ℃ and held for 120 minutes; after completion, it is naturally cooled to room temperature, and the burrs are removed by mechanical processing to obtain benzoxazine resin-based friction material.
[0050] Comparative Example 3: A method for preparing a benzoxazine resin-based composite friction material includes the following steps: Step 1: Prepare the mixed powder: Add 10% by mass of polyacrylonitrile-based carbon fiber, 4% by mass of pitch-based carbon fiber, and 6% by mass of aramid fiber into a high-speed mixer. Set the speed to 10,000 rpm, and stir for 3 seconds followed by 5 minutes of resting. Repeat this operation 3 times. Then, add 25% by mass of bisphenol A type benzoxazine resin and 55% by mass of composite filler to the above mixed fibers. The composite filler consists of 10% calcium sulfate, 10% barium sulfate, 5% alumina, 12% calcium carbonate, 10% diatomaceous earth, 5% graphite, 2% molybdenum disulfide, and 1% carbon black. Continue mixing at 10,000 rpm, and repeat the cycle of stirring for 3 seconds and resting for 5 minutes 3 times to obtain a uniform mixed powder.
[0051] Step 2, hot pressing: Take an appropriate amount of the mixed powder and fill it into the preset mold. Set the hot pressing temperature to 200℃, the molding pressure to 10 MPa, and the pressing time to 900 seconds. No venting is required during the pressing process. After the material has completely solidified, demold to obtain the preform.
[0052] Step 3, preparation of friction material: The preform is placed in an oven for heat treatment, heated to 205 ℃ and held for 120 minutes; after completion, it is naturally cooled to room temperature, and the burrs are removed by mechanical processing to obtain benzoxazine resin-based friction material.
[0053] Comparative Example 4: A method for preparing a benzoxazine resin-based composite friction material includes the following steps: Step 1: Prepare the mixed powder: Add 10% by mass of polyacrylonitrile-based carbon fiber, 4% by mass of pitch-based carbon fiber, and 6% by mass of aramid fiber into a high-speed mixer. Set the speed to 10,000 rpm, and stir for 3 seconds followed by 5 minutes of resting. Repeat this operation 3 times. Then, add 20% by mass of bisphenol A type benzoxazine resin and 60% by mass of composite filler to the above mixed fibers. The composite filler consists of 10% calcium sulfate, 10% barium sulfate, 5% alumina, 17% calcium carbonate, 10% diatomaceous earth, 5% graphite, 2% molybdenum disulfide, and 1% carbon black. Continue mixing at 10,000 rpm, and repeat the cycle of stirring for 3 seconds and resting for 5 minutes 3 times to obtain a uniform mixed powder.
[0054] Step 2, hot pressing: Take an appropriate amount of the mixed powder and fill it into the preset mold. Set the hot pressing temperature to 200℃, the molding pressure to 10 MPa, and the pressing time to 900 seconds. No venting is required during the pressing process. After the material has completely solidified, demold to obtain the preform.
[0055] Step 3, preparation of friction material: The preform is placed in an oven for heat treatment, heated to 205 ℃ and held for 120 minutes; after completion, it is naturally cooled to room temperature, and the burrs are removed by mechanical processing to obtain benzoxazine resin-based friction material.
[0056] Example 1: A method for preparing a triangular-plate-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material includes the following steps: Step 1: Preparation of mixed powder: 10% polyacrylonitrile-based carbon fiber, 4% pitch-based carbon fiber, and 6% aramid fiber by mass are added to a high-speed mixer. The speed is set to 10,000 rpm. After stirring for 3 seconds each time, the mixture is allowed to stand for 5 minutes. This operation is repeated 3 times. Subsequently, 30% bisphenol A type benzoxazine resin and 50% composite filler by mass are added to the above mixed fibers. The composite filler consists of 10% calcium sulfate, 10% barium sulfate, 5% alumina, 7% calcium carbonate, 10% diatomaceous earth, 5% LaCO3OH, 2% molybdenum disulfide, and 1% carbon black. Mixing continues at 10,000 rpm. The same cycle of stirring for 3 seconds and standing for 5 minutes is repeated 3 times to obtain a uniform mixed powder.
[0057] Step 2, hot pressing: Take an appropriate amount of the mixed powder and fill it into the preset mold. Set the hot pressing temperature to 200℃, the molding pressure to 10 MPa, and the pressing time to 900 seconds. No venting is required during the pressing process. After the material has completely solidified, demold to obtain the preform.
[0058] Step 3, preparation of friction material: The preform is placed in an oven for heat treatment, heated to 205 ℃ and held for 120 minutes; after completion, it is naturally cooled to room temperature, and the burrs are removed by mechanical processing to obtain benzoxazine resin-based friction material.
[0059] Example 2: A method for preparing a triangular-plate-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material includes the following steps: Step 1: Preparation of mixed powder: 10% polyacrylonitrile-based carbon fiber, 4% pitch-based carbon fiber, and 6% aramid fiber by mass are added to a high-speed mixer. The speed is set to 10,000 rpm. After stirring for 3 seconds each time, the mixture is allowed to stand for 5 minutes. This operation is repeated 3 times. Subsequently, 25% bisphenol A type benzoxazine resin and 55% composite filler by mass are added to the above mixed fibers. The composite filler consists of 10% calcium sulfate, 10% barium sulfate, 5% alumina, 12% calcium carbonate, 10% diatomaceous earth, 5% LaCO3OH, 2% molybdenum disulfide, and 1% carbon black. Mixing continues at 10,000 rpm. The same cycle of stirring for 3 seconds and standing for 5 minutes is repeated 3 times to obtain a uniform mixed powder.
[0060] Step 2, hot pressing: Take an appropriate amount of the mixed powder and fill it into the preset mold. Set the hot pressing temperature to 200℃, the molding pressure to 10 MPa, and the pressing time to 900 seconds. No venting is required during the pressing process. After the material has completely solidified, demold to obtain the preform.
[0061] Step 3, preparation of friction material: The preform is placed in an oven for heat treatment, heated to 205 ℃ and held for 120 minutes; after completion, it is naturally cooled to room temperature, and the burrs are removed by mechanical processing to obtain benzoxazine resin-based friction material.
[0062] Example 3: A method for preparing a triangular-plate-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material includes the following steps: Step 1: Preparation of mixed powder: 10% polyacrylonitrile-based carbon fiber, 4% pitch-based carbon fiber, and 6% aramid fiber by mass are added to a high-speed mixer. The speed is set to 10,000 rpm. After stirring for 3 seconds each time, the mixture is allowed to stand for 5 minutes. This operation is repeated 3 times. Subsequently, 20% benzoxazine resin and 60% composite filler by mass are added to the above mixed fibers. The composite filler consists of 10% calcium sulfate, 10% barium sulfate, 5% alumina, 17% calcium carbonate, 10% diatomaceous earth, 5% LaCO3OH, 2% molybdenum disulfide, and 1% carbon black. Mixing continues at 10,000 rpm. The cycle is also 3 times, with stirring for 3 seconds and standing for 5 minutes, to obtain a uniform mixed powder.
[0063] Step 2, hot pressing: Take an appropriate amount of the mixed powder and fill it into the preset mold. Set the hot pressing temperature to 200℃, the molding pressure to 10 MPa, and the pressing time to 900 seconds. No venting is required during the pressing process. After the material has completely solidified, demold to obtain the preform.
[0064] Step 3, preparation of friction material: The preform is placed in an oven for heat treatment, heated to 205 ℃ and held for 120 minutes; after completion, it is naturally cooled to room temperature, and the burrs are removed by mechanical processing to obtain benzoxazine resin-based friction material.
[0065] To verify the technical effects of the present invention, the friction materials prepared in the embodiments and comparative examples were tested for compression performance, shear performance, and tribological properties.
[0066] Figure 1 Thermogravimetric analysis (TGA) curves of bisphenol A type benzoxazine resin and phenolic resin are shown. Compared with phenolic resin, bisphenol A type benzoxazine resin has a higher initial thermal decomposition temperature and a higher temperature corresponding to the maximum thermal weight loss rate, and exhibits less mass loss in the 300–500 °C range. Its residual carbon content is approximately 61.9%, higher than the 52.3% of phenolic resin. These performance differences are related to the cross-linked structure formed by bisphenol A type benzoxazine resin under high-temperature conditions, which enables it to maintain better structural stability in high-temperature environments, thus making it suitable for high-temperature or high-load frictional conditions.
[0067] Figure 2 Scanning electron microscopy (SEM) images and elemental distribution maps of triangular plate-shaped lanthanum hydroxycarbonate (LaCO3OH) prepared by a hydrothermal method are shown. Low-magnification images reveal a regular triangular plate-like morphology with relatively straight edges and a smooth surface. Some plate-like particles exhibit locally ordered, tightly packed arrangements. High-magnification images further show that the triangular plate-like particles have a side length of approximately 6–7 μm, exhibiting distinct two-dimensional plate-like structural characteristics. Elemental distribution results indicate that La, C, and O elements are relatively uniformly distributed. This lanthanum-based rare earth compound can not only serve as a structural filler but also participate in the formation of interfacial films during friction.
[0068] Figure 3 The XRD pattern and standard PDF card of the corresponding sample show that all diffraction peaks are consistent with the LaCO3OH standard card (PDF#00-026-0815), indicating that the obtained product is hexagonal lanthanum hydroxycarbonate and no obvious impurity phase peaks were observed.
[0069] Figure 4 The mechanical properties of each comparative example and embodiment at room temperature are given. Figure 4(a) It can be seen that Comparative Example 1, which uses phenolic resin, has a compressive strength of 232 MPa. Comparative Examples 2 to 4, which use benzoxazine resin and do not contain triangular lamellar LaCO3OH filler, have compressive strengths of 279 MPa, 243 MPa, and 229 MPa, respectively, and compressive moduli of 4421 MPa, 4190 MPa, and 3924 MPa, respectively. After adding triangular lamellar LaCO3OH filler, the compressive strengths of Examples 1 to 3 increased to 336 MPa, 301 MPa, and 233 MPa, respectively, and the compressive moduli of 4443 MPa, 4890 MPa, and 4237 MPa, respectively. Among them, Example 1 has the highest compressive strength, which is 44.8% higher than that of Comparative Example 1; Example 2 has the highest compressive modulus, reaching 4890 MPa.
[0070] Figure 4 (b) Comparison of shear strength between comparative examples and embodiments. The shear strength of comparative example 1 was 47 MPa, comparative examples 2-4 were 60 MPa, 58 MPa, and 57 MPa, respectively, and embodiments 1-3 were 55 MPa, 53 MPa, and 41 MPa, respectively. The results show that the benzoxazine resin system has high shear strength; based on this, the addition of triangular laCO3OH filler further improves the compressive properties while maintaining a high shear strength level.
[0071] The aforementioned performance differences are related to the binder system and filler structure. Phenolic resins easily release small-molecule byproducts during curing, leading to more pores or interface defects within the material. In contrast, benzoxazine resins, cured through ring-opening polymerization, produce fewer byproducts, facilitating the formation of a denser matrix structure. Furthermore, the triangular lamellar LaCO3OH filler plays a role in load bearing and stress transfer within the matrix. Its lamellar structure restricts local deformation and hinders crack propagation under stress, resulting in higher compressive strength and compressive modulus. The results indicate that by replacing phenolic resin with benzoxazine resin and introducing triangular lamellar LaCO3OH filler, the composite friction material obtained in this invention exhibits higher load-bearing capacity and structural stability, which is beneficial for improving the reliability and durability of the material under high loads and complex braking conditions.
[0072] Figure 5The figure shows the variation of the friction coefficient of the resin-based friction materials prepared in the comparative examples and embodiments within a braking pressure range of 0.5 MPa to 5 MPa. As can be seen from the figure, within the pressure range of 0.5 to 5 MPa, the dynamic friction coefficient of each sample decreases with increasing pressure. The friction coefficient of Comparative Example 1 decreased from 0.336 to 0.224, a decrease of approximately 33.3%, indicating that the traditional phenolic resin system is relatively sensitive to pressure changes. After using benzoxazine resin, the overall pressure sensitivity of each sample was improved. Furthermore, after adding triangular laCO3OH filler, Example 1 exhibited better frictional stability; its friction coefficient decreased significantly less with increasing pressure than that of Comparative Example 1, indicating that the material of the present invention can maintain more stable frictional behavior over a wider pressure range.
[0073] The above results are related to the synergistic effect of benzoxazine resin and triangular lacoplasmic LaCO3OH filler. The matrix structure formed by benzoxazine resin is relatively dense, which is beneficial to improving the stability of the friction interface; the triangular lacoplasmic LaCO3OH filler can participate in the formation of the interfacial film during friction. Its lacoplasmic structure and fragments can be embedded in the friction interface, promoting the formation of a more continuous friction film, thereby reducing the direct contact between friction pairs and mitigating the adverse effects of increased pressure on the friction coefficient. In summary, this invention, by using benzoxazine resin and introducing triangular lacoplasmic LaCO3OH filler, can effectively improve the frictional stability of resin-based friction materials under high pressure conditions, with Example 1 exhibiting superior pressure adaptability.
[0074] Figure 6 The figure shows the volumetric wear rate of the resin-based friction materials prepared in Comparative Example 1 and Examples 1-3 under braking pressures ranging from 0.5 MPa to 5 MPa. As can be seen from the figure, the wear rate of each sample increases with increasing braking pressure. Comparative Example 1 exhibits the highest wear rate throughout the entire pressure range, reaching approximately 18.2 × 10⁻⁶ at 5 MPa. -8 cm 3 / J indicates that traditional phenolic resin systems are more prone to wear under high pressure. In contrast, the wear rates of Examples 1-3 of this invention are significantly lower than those of Comparative Example 1 within the same pressure range, indicating that the wear resistance of the material is significantly improved after using benzoxazine resin and introducing triangular lamellar LaCO3OH filler. Among them, Example 2 exhibits a relatively low wear rate overall under various pressure conditions, approximately 2.8 × 10⁻⁶ at 5 MPa pressure. -8 cm 3The wear resistance is most outstanding. This result is related to the role of the triangular lamellar LaCO3OH filler in the friction process. The filler and its fragments can participate in the formation of the friction interface film. Its lamellar structure helps to distribute local loads and reduce contact stress concentration, thereby inhibiting wear aggravation under high pressure conditions. Therefore, the composite friction material obtained in this invention exhibits good wear resistance over a wide pressure range.
[0075] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.
Claims
1. A triangular-plate-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material, characterized in that, By weight percentage, including 20% 30% organic binder, 20% fiber-reinforced phase, and 50%... 60% inorganic filler; The organic binder is a benzoxazine resin; The inorganic filler is one or more of the following: calcium sulfate, barium sulfate, alumina, calcium carbonate, zirconium oxide, chromite, diamond powder, silicon dioxide, graphite, molybdenum disulfide, tungsten disulfide, diatomite, vermiculite, kaolin, and carbon black, and contains at least 5% triangular laco3OH; wherein the triangular laco3OH exhibits a regular triangular morphology, with straight edges, a smooth surface, and a side length of 6~7 μm.
2. The triangular-plate-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material according to claim 1, characterized in that, The benzoxazine resin is one or more of the following: bisphenol A type benzoxazine resin, bisphenol F type benzoxazine resin, phenolphthalein type benzoxazine resin, dicyclopentadiene type benzoxazine resin, phosphorus-containing benzoxazine resin, and diamine type benzoxazine resin; The fiber reinforcement phase is one or more of polyacrylonitrile-based carbon fiber, pitch-based carbon fiber, aramid fiber, mineral fiber, basalt fiber, glass fiber and steel fiber; wherein, the polyacrylonitrile-based carbon fiber and the pitch-based carbon fiber are both short-cut carbon fibers with a length of 40~100 μm and a diameter of 8~20 μm.
3. The triangular-plate-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material according to claim 1, characterized in that, The triangular-shaped LaCO3OH is dispersed in the matrix and locally forms an ordered stacked structure. The sheet-shaped fillers form a layered arrangement structure through overlapping and contact.
4. The triangular-plate-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material according to claim 1, characterized in that, The preparation method of the triangular plate-shaped LaCO3OH includes the following steps: S1: Dissolve lanthanum chloride hexahydrate in deionized water by stirring to obtain a precursor solution; S2: Under stirring conditions, concentrated ammonia is added dropwise to the precursor solution to adjust the pH of the system. Then urea is added, stirred to dissolve, and then the volume is adjusted to obtain the reaction solution. S3: The reaction solution is placed in a hydrothermal reactor to react and obtain a reaction mixture; S4: The reaction mixture is naturally cooled to room temperature, and after solid-liquid separation, it is washed several times with deionized water and anhydrous ethanol, and then vacuum dried to obtain triangular sheet-like LaCO3OH.
5. The triangular-plate-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material according to claim 4, characterized in that, In S1, the precursor solution contains La 3+ The concentration is 0.03~0.05 mol / L; In S2, the concentrated ammonia solution has a mass fraction of 25%~28%, and the system pH is 8.0~9.0; the amount of urea added is La. 3+ Four times the molar amount; In S3, the filling degree of the reaction liquid in the hydrothermal reactor is 70%~80%, the reaction temperature is 130 ℃, and the time is 8h.
6. The triangular-plate-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material according to claim 1, characterized in that, The coefficient of friction under pressure of 0.5-5 MPa is 0.21~0.31, and the volumetric wear rate is 0.0105~0.0414 cm. 3 / MJ.
7. A method for preparing a triangular sheet-like LaCO3OH-reinforced benzoxazine resin-based composite friction material according to any one of claims 1 to 6, characterized in that, Includes the following steps: A fiber-reinforced phase is prepared by mixing the fiber-reinforced phase, organic binder, and inorganic filler to obtain a mixed powder. The mixed powder is loaded into a mold and hot-pressed for curing. After demolding, a preform is obtained. The preform is heat-treated, then cooled to room temperature, and then machined to obtain a triangular-shaped LaCO3OH-reinforced benzoxazine resin-based composite friction material.
8. The method for preparing a triangular sheet-like LaCO3OH-reinforced benzoxazine resin-based composite friction material according to claim 7, characterized in that, In the process of preparing the fiber reinforcement phase, the mixing speed is 8000 rpm to 12000 rpm, the mixing time is 2 s to 5 s, the interval between each mixing is 3 min to 6 min, and the mixing is repeated 3 times. The mixing speed is 8000 rpm to 12000 rpm, the mixing time for a single mixing is 2 s to 5 s, the interval between each mixing is 3 min to 6 min, and the mixing is repeated 3 times.
9. A method for preparing a triangular laCO3OH-reinforced benzoxazine resin-based composite friction material according to claim 7, characterized in that, The conditions for hot-press curing are as follows: temperature is 150 ℃~220 ℃, pressure is 8 MPa~15 MPa, and time is 600 s~1000 s; The heat treatment conditions are as follows: the treatment temperature is 150 ℃~220 ℃, and the holding time is 100 min~150 min.
10. The application of the triangular laCO3OH-reinforced benzoxazine resin-based composite friction material according to any one of claims 1 to 6 in brake pads.