A method for preparing a resin-based friction material for enhancing torque limiters and its formulation.

Abstract

This invention discloses a method for preparing a resin-based friction material for enhancing torque limiters, comprising the following steps: Step 1, performing surface and interface modification treatment on the metal powder, thereby constructing a multi-level composite interface structure on the surface of the metal powder, consisting of a roughening layer, an activation transition layer, and an organic coupling layer. The organic coupling layer is composed of organic molecules containing active groups, used to form chemical bonds between the metal surface and the resin; Step 2, mixing the metal powder with the multi-level composite interface structure with modified phenolic resin, fibers, and fillers; Step 3, pressing and heating the mixed material to form a friction composite material with a continuous interface bridging structure; the corresponding formulation is also disclosed. The wear rate of the product of this invention is reduced by more than 50% compared with the unmodified system, the compressive strength is increased by more than 20%, and the friction coefficient is significantly improved and remains stable, exhibiting excellent comprehensive friction performance.

Description

Technical Field

[0001] This invention relates to a method for preparing a resin-based friction material for enhancing torque limiters and its formulation. Background Technology

[0002] In torque limiters and similar friction transmission devices, resin-based friction materials are often used. These materials typically use phenolic resin as the matrix and add metal powder, fibers, and fillers to achieve certain strength and friction properties.

[0003] In existing technologies, one type of solution improves performance by adjusting the material formulation. For example, patent CN106086718A discloses a clutch iron-based composite friction material and its preparation method. By optimizing the proportions of components such as iron powder and carbides, and combining sintering and heat treatment processes, the wear resistance and strength of the material are improved. However, this type of solution mainly relies on adjusting the overall material composition and lacks effective control over the bonding state between the metal particles and the matrix. Under long-term friction or high-temperature conditions, particle shedding and accelerated wear are still prone to occur.

[0004] Another type of technical solution improves friction performance by introducing larger-sized hard particles. For example, patent CN106928649A discloses a novel ceramic particle composite resin-based anti-heat-fading friction material and its preparation method, which uses larger-sized ceramic particles as a reinforcing phase to improve friction stability and heat resistance. However, this type of solution mainly relies on the effect of macroscopic particles and does not specifically address the interface between the particles and the resin, resulting in problems such as weak interfacial bonding and localized delamination, thus affecting the overall service life.

[0005] Therefore, the following problems generally exist in the existing technology: The bonding between the metal powder and the resin matrix is ​​unstable; Under high temperature or repeated friction conditions, wear is easily accelerated and performance fluctuations occur. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and formulation for preparing a resin-based friction material for enhanced torque limiters that improves the bonding stability between metal powder and resin and reduces material wear without relying on a complex material system.

[0007] The technical solution of the present invention is: a method for preparing a resin-based friction material for enhancing torque limiters, comprising the following steps: Step 1: Perform surface and interface modification treatment on the metal powder to form a multi-level composite interface structure with coarsened structure and active sites on the surface of the metal powder. The multi-level composite interface structure includes: A roughening layer formed by nitric acid oxidation on the surface of metal powder is used to increase the specific surface area and mechanical interlocking effect; An activated transition layer, formed by low-temperature plasma treatment and disposed on the surface of the roughened layer, is used to provide active binding sites. An organic coupling layer is formed by impregnation with silane coupling agent KH-550 or tannic acid solution on the surface of the activated transition layer. The organic coupling layer is composed of organic molecules containing active groups and is used to form chemical bonds between the metal surface and the resin. Step 2: Mix the metal powder with the multi-level composite interface structure with the modified phenolic resin, fiber and filler; Step 3: Press and heat the mixed material to cure it, forming a friction composite material with a continuous interface bridging structure; Ultimately, a three-dimensional skeleton structure composed of metal powder, fiber and resin is formed inside the friction composite material, creating a continuous load transfer path between the interfaces.

[0008] Furthermore, through the hot-press curing process, a composite microstructure with alternating soft and hard phases is formed inside the obtained friction material, and a dense and stable friction film is formed on the surface of the friction material.

[0009] A formulation for preparing a resin-based friction material for enhancing torque limiters comprises, by weight: 35-43 parts modified phenolic resin; 12-18 parts glass fiber; 8-13 parts calcium carbonate; 6-10 parts graphite; 7-9 parts barium sulfate; 13-15 parts interface-modified metal powder; and 5 parts curing agent.

[0010] Specifically, the interface-modified metal powder is one or more of interface-modified copper powder, interface-modified iron powder, or interface-modified tungsten-copper composite powder, and the modified phenolic resin is boron-modified phenolic resin, melamine-modified phenolic resin, or a mixture of the two modified phenolic resins.

[0011] Furthermore, it also includes 1 to 3 parts of functional filler, wherein the functional filler is one or more of bamboo charcoal, carbon fiber and cerium oxide.

[0012] Preferably, the formulation of a method for preparing a resin-based friction material for enhancing torque limiters comprises the following raw materials by mass: 40 parts boron-modified phenolic resin, 15 parts glass fiber, 10 parts calcium carbonate, 8 parts graphite, 7 parts barium sulfate, 15 parts interface-modified copper powder, and 5 parts hexamethylenetetramine.

[0013] Preferably, the formulation of a method for preparing a resin-based friction material for enhancing torque limiters comprises the following raw materials by mass: 35 parts melamine-modified phenolic resin, 18 parts glass fiber, 12 parts calcium carbonate, 7 parts graphite, 8 parts barium sulfate, 15 parts interface-modified iron powder, and 5 parts polyamide.

[0014] Preferably, the formulation of a method for preparing a resin-based friction material for enhancing torque limiters comprises the following raw materials by mass: 38 parts boron-melamine mixed modified phenolic resin, 16 parts glass fiber, 11 parts calcium carbonate, 8 parts graphite, 7 parts barium sulfate, 15 parts interface-modified tungsten copper powder, and 5 parts hexamethylenetetramine.

[0015] Preferably, the formulation of a method for preparing a resin-based friction material for enhancing torque limiters comprises the following raw materials by mass: 43 parts boron-modified phenolic resin, 12 parts glass fiber, 8 parts calcium carbonate, 10 parts graphite, 7 parts barium sulfate, 13 parts interface-modified iron powder, 2 parts bamboo charcoal, and 5 parts polyamide.

[0016] Preferably, the formulation of a method for preparing a resin-based friction material for enhancing torque limiters comprises the following raw materials by mass: 37 parts of melamine-modified phenolic resin, 14 parts of glass fiber, 13 parts of calcium carbonate, 6 parts of graphite, 9 parts of barium sulfate, 14 parts of interface-modified tungsten copper powder, 2 parts of cerium oxide, and 5 parts of hexamethylenetetramine.

[0017] The beneficial effects of this invention are as follows: This invention forms a multi-layer interface structure by sequentially constructing a roughening layer, an activation transition layer, and an organic coupling layer on the surface of metal powder. It also improves thermal stability by combining modified resin and further works synergistically with functional fillers, fundamentally improving the interfacial bonding state. The wear rate of the product of this invention is reduced by more than 50% compared with the unmodified system, the compressive strength is increased by more than 20%, and the friction coefficient is significantly improved and kept stable, exhibiting excellent comprehensive friction performance. Attached Figure Description

[0018] Figure 1 This is a comparison chart of wear rates of different embodiments and control examples under 350°C conditions. Detailed Implementation

[0019] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. Example

[0020] A resin-based friction material for enhancing torque limiters comprises the following raw materials by weight: 40 parts boron-modified phenolic resin, 15 parts glass fiber, 10 parts calcium carbonate, 8 parts graphite, 7 parts barium sulfate, 15 parts interface-modified copper powder, and 5 parts hexamethylenetetramine.

[0021] Its preparation methods include: Step 1, Copper Powder Interface Modification: Oxidation with 20% nitric acid for 45 minutes (forming a roughening layer on the copper powder surface); followed by argon plasma treatment (80W, 8 minutes) (forming an activation transition layer); then treatment with KH-550 solution for 1 hour (forming an organic coupling layer on the surface). Step 2, Mixing: Mix the above ingredients at high speed for 30 minutes; Step 3: Hot pressing: Hot press at 200℃ and 40MPa for 20 minutes.

[0022] In step one, the roughening layer formed by nitric acid oxidation on the surface of the metal powder is used to increase the specific surface area and mechanical interlocking effect. The activation transition layer formed by low-temperature plasma treatment is used to provide active binding sites. The organic coupling layer formed by impregnation treatment with silane coupling agent KH-550 solution is composed of organic molecules containing active groups and is used to form chemical bonds between the metal surface and the resin. Ultimately, a three-dimensional skeleton structure composed of metal powder, fiber and resin is formed inside the friction composite material, which creates a continuous load transfer path between the interfaces, thereby significantly improving the interfacial bonding strength and reducing the wear rate. Performance: Coefficient of friction 0.35, wear rate at 350℃ 0.85×10⁻ 7 cm³ / (N·m), compressive strength 300MPa. Example

[0023] Raw materials: 35 parts melamine-modified phenolic resin, 18 parts glass fiber, 12 parts calcium carbonate, 7 parts graphite, 8 parts barium sulfate, 15 parts interface-modified iron powder, and 5 parts polyamide.

[0024] Key points of the process: Iron powder was oxidized with 20% nitric acid for 45 minutes, followed by oxygen plasma treatment (70W, 10 minutes), and surface modified with tannic acid; the hot pressing conditions were 220℃, 45MPa, 15 minutes, and the remaining steps were the same as in Example 1.

[0025] Performance: Coefficient of friction 0.30, wear rate 0.75×10⁻ 7 The compressive strength is 305 MPa. Example

[0026] Raw materials: 38 parts boron-melamine mixed modified phenolic resin, 16 parts glass fiber, 11 parts calcium carbonate, 8 parts graphite, 7 parts barium sulfate, 15 parts interface modified tungsten copper powder, and 5 parts hexamethylenetetramine.

[0027] Key points of the process: Tungsten copper powder was oxidized with 20% nitric acid for 45 minutes, followed by argon plasma (90W, 7 minutes) + tannic acid treatment; the hot pressing conditions were 230℃, 50MPa, 25 minutes, and the remaining steps were the same as in Example 1.

[0028] Performance: Coefficient of friction 0.34, wear rate 0.72×10⁻ 7 The compressive strength is 320 MPa. Example

[0029] Raw materials: 43 parts boron-modified phenolic resin, 12 parts glass fiber, 8 parts calcium carbonate, 10 parts graphite, 7 parts barium sulfate, 13 parts interface-modified iron powder, 2 parts bamboo charcoal, and 5 parts polyamide.

[0030] Key points of the process: Iron powder was oxidized with 20% nitric acid for 45 minutes, followed by oxygen plasma (60W, 8 minutes) + KH550 treatment; hot pressing conditions were 210℃, 35MPa, 18 minutes, and the remaining steps were the same as in Example 1.

[0031] Performance: Coefficient of friction 0.31, wear rate 0.68×10⁻ 7 Compressive strength 300MPa. Example

[0032] Raw materials: 37 parts melamine-modified phenolic resin, 14 parts glass fiber, 13 parts calcium carbonate, 6 parts graphite, 9 parts barium sulfate, 14 parts interface-modified tungsten copper powder, 2 parts cerium oxide, and 5 parts hexamethylenetetramine.

[0033] Key points of the process: Tungsten copper powder was oxidized with 20% nitric acid for 45 minutes, followed by argon plasma (85W, 9 minutes) + tannic acid treatment; hot pressing conditions were 225℃, 40MPa, 20 minutes, and the remaining steps were the same as in Example 1.

[0034] Performance: Coefficient of friction 0.30, wear rate 0.64×10⁻ 7 The compressive strength is 315 MPa.

[0035] Compare with Example 1 The ordinary phenolic resin system was used, but the copper powder was not modified at the interface. The rest of the formulation and process were the same as in Example 1.

[0036] Performance: Coefficient of friction 0.22, wear rate 1.80×10⁻ 7 Compressive strength 250MPa.

[0037] Compare with Example 2 In the ordinary phenolic resin system, the iron powder was only subjected to nitric acid oxidation treatment (20%, 45 minutes), and the rest was the same as in Example 2.

[0038] Performance: Coefficient of friction 0.25, wear rate 1.64×10⁻ 7 The compressive strength is 260 MPa.

[0039] Performance Comparison Table: Figure 1 This is a comparison chart of wear rates of different embodiments and control examples at 350°C, with reference to the performance comparison table and... Figure 1As shown, compared with the control example, this solution has achieved systematic improvements in three core indicators: 1. Significantly improved wear resistance.

[0040] Compare with Example 1: 1.80 × 10⁻ 7 ; Compare with Example 2: 1.64 × 10⁻ 7 ; Example range: 0.64~0.85×10⁻ 7 .

[0041] The improvement of this solution is approximately 48% to 64%. Among them, Example 5 showed the best wear rate, which was reduced by 64.4% compared to Control Example 1. This solution can significantly suppress high-temperature wear.

[0042] 2. The compressive strength is steadily improved.

[0043] Reference value: 250–260 MPa; Example: 300-320 MPa.

[0044] The improvement of this solution is approximately 15% to 28%. Among them, Example 3 has the highest compressive strength. The interface strengthening and resin modification of this solution significantly improve the structural load-bearing capacity.

[0045] 3. The coefficient of friction increases and tends to stabilize.

[0046] Control examples: 0.22–0.25; Example: 0.30~0.35.

[0047] This solution improves friction output by approximately 20% to 60%, resulting in more stable friction output and effectively preventing slippage of the produced friction plates.

[0048] It is worth mentioning that, under the premise of similar materials and processes, the interface-modified metal powders in Examples 1-5 were all subjected to nitric acid oxidation, low-temperature plasma treatment and impregnation with silane coupling agent KH-550 or tannic acid solution in sequence, forming a multi-level composite interface structure of roughening layer, activation transition layer and organic coupling layer on the surface of metal powder. The roughening layer on the surface of the metal powder is used to increase the specific surface area and mechanical interlocking effect, the activation transition layer is used to provide active binding sites, and the organic coupling layer is composed of organic molecules containing active groups, which is used to form chemical bonds between the metal surface and the resin. Finally, a three-dimensional skeleton structure composed of metal powder, fiber and resin is formed inside the friction material, so as to form a continuous load transfer path between the interfaces, thereby significantly improving the interfacial bonding strength and reducing the wear rate. The metal powder in Comparative Example 1, which was untreated, had the worst performance. The metal powder in Comparative Example 2, which underwent only oxidation treatment, still showed a significant performance difference compared to Examples 1-5.

[0049] In addition, the comparison also shows that the use of modified phenolic resin matrix can improve carbonization rate and inhibit thermal decomposition. When combined with interface modified metal powder, it can play a synergistic strengthening role and ultimately reduce the wear rate of the product. Among the raw materials for interface-modified metal powders, copper powder has good thermal conductivity, high friction, and the highest coefficient of friction (0.35); iron powder has good stability and balanced performance; tungsten copper has high temperature stability, high strength, and optimal wear resistance; therefore, tungsten copper composite powder can provide the best comprehensive performance. In functional additives, bamboo charcoal acts as an adsorbent and lubricant, reducing product wear rate to 0.68×10⁻ 7 Cerium oxide improves the high-temperature stability and antioxidant properties of the product, enabling it to achieve a temperature of 0.64 × 10⁻⁻⁻⁶. 7 A better wear rate; In summary, this solution constructs a multi-layered interface structure on the surface of metal powder by sequentially building a roughening layer, an activation transition layer, and an organic coupling layer. This, combined with modified resin to improve thermal stability and synergistic effect with functional fillers, fundamentally improves the interfacial bonding state, thereby effectively suppressing wear and structural degradation under high-temperature conditions. Experimental results show that the wear rate of the material produced by this solution is reduced by more than 50% compared to the unmodified system, the compressive strength is increased by more than 20%, and the friction coefficient is significantly improved and remains stable, demonstrating excellent comprehensive friction performance.

Claims

1. A method for preparing a resin-based friction material for enhancing torque limiters, characterized in that, Includes the following steps: Step 1: Perform surface and interface modification treatment on the metal powder to form a multi-level composite interface structure with coarsened structure and active sites on the surface of the metal powder. The multi-level composite interface structure includes: A roughening layer formed by nitric acid oxidation on the surface of metal powder is used to increase the specific surface area and mechanical interlocking effect; An activated transition layer, formed by low-temperature plasma treatment and disposed on the surface of the roughened layer, is used to provide active binding sites. An organic coupling layer is formed by impregnation with silane coupling agent KH-550 or tannic acid solution on the surface of the activated transition layer. The organic coupling layer is composed of organic molecules containing active groups and is used to form chemical bonds between the metal surface and the resin. Step 2: Mix the metal powder with the multi-level composite interface structure with the modified phenolic resin, fiber and filler; Step 3: Press and heat the mixed material to cure it, forming a friction composite material with a continuous interface bridging structure; Ultimately, a three-dimensional skeleton structure composed of metal powder, fiber and resin is formed inside the friction composite material, creating a continuous load transfer path between the interfaces.

2. The method for preparing a resin-based friction material for an enhanced torque limiter as described in claim 1, characterized in that, Through the hot-press curing process, a composite microstructure of alternating soft and hard phases is formed inside the obtained friction material, and a dense and stable friction film is formed on the surface of the friction material.

3. The formulation of the method for preparing a resin-based friction material for an enhanced torque limiter as described in claim 1, characterized in that, By weight, it includes: 35-43 parts modified phenolic resin; 12-18 parts glass fiber; 8-13 parts calcium carbonate; 6-10 parts graphite; 7-9 parts barium sulfate; 13-15 parts interface-modified metal powder; and 5 parts curing agent.

4. The formulation of the method for preparing a resin-based friction material for an enhanced torque limiter as described in claim 3, characterized in that, The interface-modified metal powder is one or more of interface-modified copper powder, interface-modified iron powder, or interface-modified tungsten-copper composite powder, and the modified phenolic resin is boron-modified phenolic resin, melamine-modified phenolic resin, or a mixture of the two modified phenolic resins.

5. The formulation of the method for preparing a resin-based friction material for an enhanced torque limiter as described in claim 4, characterized in that, It also includes 1 to 3 parts of functional filler, wherein the functional filler is one or more of bamboo charcoal, carbon fiber and cerium oxide.

6. The formulation of the method for preparing a resin-based friction material for an enhanced torque limiter as described in claim 5, characterized in that, The raw materials, by weight, include: 40 parts boron-modified phenolic resin, 15 parts glass fiber, 10 parts calcium carbonate, 8 parts graphite, 7 parts barium sulfate, 15 parts interface-modified copper powder, and 5 parts hexamethylenetetramine.

7. The formulation of the method for preparing a resin-based friction material for an enhanced torque limiter as described in claim 5, characterized in that, The raw materials, by weight, include: 35 parts melamine-modified phenolic resin, 18 parts glass fiber, 12 parts calcium carbonate, 7 parts graphite, 8 parts barium sulfate, 15 parts interface-modified iron powder, and 5 parts polyamide.

8. The formulation of the method for preparing a resin-based friction material for an enhanced torque limiter as described in claim 5, characterized in that, The raw materials, by weight, include: 38 parts boron-melamine mixed modified phenolic resin, 16 parts glass fiber, 11 parts calcium carbonate, 8 parts graphite, 7 parts barium sulfate, 15 parts interface modified tungsten copper powder, and 5 parts hexamethylenetetramine.

9. The formulation of the method for preparing a resin-based friction material for an enhanced torque limiter as described in claim 5, characterized in that, The raw materials, by weight, include: 43 parts boron-modified phenolic resin, 12 parts glass fiber, 8 parts calcium carbonate, 10 parts graphite, 7 parts barium sulfate, 13 parts interface-modified iron powder, 2 parts bamboo charcoal, and 5 parts polyamide.

10. The formulation of the method for preparing a resin-based friction material for an enhanced torque limiter as described in claim 5, characterized in that, The raw materials, by weight, include: 37 parts melamine-modified phenolic resin, 14 parts glass fiber, 13 parts calcium carbonate, 6 parts graphite, 9 parts barium sulfate, 14 parts interface-modified tungsten copper powder, 2 parts cerium oxide, and 5 parts hexamethylenetetramine.

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