Powder-pressed brake disc formula containing glass fibers and preparation process of powder-pressed brake disc formula

Abstract

The invention relates to the technical field of brake disc preparation, and particularly discloses a formula of a powder-pressed brake disc containing glass fibers and a preparation process of the powder-pressed brake disc containing the glass fibers. The invention relates to a high-strength steel wool composite material which comprises the following components in percentage by weight: 14-18% of steel wool, 4-6% of barite, 8-12% of artificial graphite, 4-6% of aluminum oxide, 10-15% of phenolic resin, 42-46% of foam iron powder, 0.5-1.5% of tire powder, 4-6% of magnesium oxide and 1-3% of fiber materials, wherein the fiber materials comprise glass fibers. The process comprises the following steps; weighing the pretreated raw materials, the non-pretreated raw materials and the glass fibers according to the formula; pretreatment: vacuum drying the pretreated raw materials, mixing the pretreated and non-pretreated raw materials for 45 minutes, adding glass fibers for 5 minutes, preheating a mold to 90 DEG C, 168 DEG C, pressing for 13 minutes under 23 MPa, stepwise heating to 180 DEG C, performing staged heat preservation, and slowly cooling under inert gas. The invention aims to solve the problems that a friction disc is made of asbestos and other materials, carcinogens are easily generated, the friction disc is not environment-friendly, and the high-temperature friction performance is low.

Description

Technical Field

[0001] The present invention relates to the technical field of brake disc preparation, and particularly relates to a powder-pressed brake disc formula containing glass fiber and its preparation process. Background Art

[0002] The continuous increase in the number of automobiles in use has promoted the progress of automotive braking system technology. The continuous growth of vehicle driving speed and load scale is positively correlated with the working intensity of the braking system, which has gradually increased the requirements for automotive braking technology. Therefore, the anti-fatigue strength of friction discs has also become the focus of attention in actual research and development and application. When selecting friction materials for existing brake discs, materials with high wear resistance and stability are more inclined to be selected as the main materials. In recent years, the brake pads used in industry are basically prepared by using phenolic resin as the matrix and adding various materials such as asbestos to the outer layer. Because the heat energy generated by the brake pads during emergency braking or normal braking is extremely easy to decompose asbestos into carcinogenic substances, the production of this kind of friction disc is prohibited in many regions. Relevant scholars at home and abroad have gradually added fiber materials to the preparation process of brake materials during exploration. Because during high-speed braking, the fiber materials mainly bear most of the loads, and when linear surface wear occurs, the fiber materials can minimize the wear of the brake disc on other materials, which enhances the performance and overall effect of the brake pads to a certain extent. Glass fiber has the characteristics of strong mechanical properties, easy recycling and low cost; and has good heat resistance, can maintain stable performance within a certain temperature range, and can withstand a temperature of 300 °C without affecting the strength. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the technical problem solved by the present invention is to provide a powder-pressed brake disc formula containing glass fiber and its preparation process, and solve the problems that existing friction discs using materials such as asbestos are prone to produce carcinogens, are not environmentally friendly, and have low high-temperature friction performance.

[0004] To solve the above problems, the technical solution adopted by the present invention is: a powder-pressed brake disc formula containing glass fiber, and the raw materials include the following components by mass percentage; 14%-18% steel wool, 4%-6% barite, 8%-12% artificial graphite, 4%-6% alumina, 10%-15% phenolic resin, 42%-46% foam iron powder, 0.5%-1.5% tire powder, 4%-6% magnesium oxide, and 1%-3% fiber material, and the fiber material includes glass fiber.

[0005] Further, the fiber material further includes aramid fiber, and the ratio of aramid fiber to glass fiber is 1:1 - 1:2.

[0006] Further, the raw materials include the following components by mass percentage: 16% steel wool, 5% barite, 10% artificial graphite, 5% alumina, 12% phenolic resin, 44% iron powder foam, 1% tire powder, 5% magnesium oxide, and 2% glass fiber.

[0007] The beneficial effects of this solution are as follows: 1%-3% glass fiber in the formula significantly improves the anti-deformation ability and structural stability of the brake disc through its high strength and high rigidity characteristics. Its high temperature resistance effectively inhibits brake thermal fade, while enhancing the fatigue resistance and extending the service life. The glass fiber cooperates with other materials to optimize the friction performance, ensuring sensitive and stable braking. Steel wool provides high-strength support to enhance the impact resistance. Artificial graphite reduces friction loss and accelerates heat dissipation due to its high lubricity. Iron powder foam optimizes the friction coefficient and heat dissipation efficiency through its porous structure. Tire powder provides elastic buffering to reduce braking noise and impact stress. Barite increases the inertial mass to improve braking stability. Alumina strengthens the surface hardness to extend the wear-resistant life. Magnesium oxide blocks heat conduction to protect the system safety. Phenolic resin, as a binder, ensures the tight combination of materials. It forms a complement with glass fiber, not only meeting the performance requirements such as high strength, high temperature resistance, and long life, but also through the environmental protection formula design, without heavy metals and low dust emissions, achieving the goal of green manufacturing, and having a high-performance brake disc product that is both safe and reliable and environmentally friendly.

[0008] A preparation process of a powder-pressed brake disc containing glass fiber includes the following steps:

[0009] Step 1: Batching; Weigh the raw materials according to the formula and divide the raw materials into pre-treated raw materials, non-pre-treated raw materials, and fiber materials. The pre-treated raw materials include barite, alumina, and magnesium oxide. The non-pre-treated raw materials include steel wool, artificial graphite, phenolic resin, iron powder foam, and tire powder.

[0010] Step 2: Raw material pre-treatment; Put the pre-treated raw materials into a dryer for drying.

[0011] Step 3: Mixing; Put the dried pre-treated raw materials and non-pre-treated raw materials into a mixer for mixing, and the mixing time is 35 - 45 minutes; then add the fiber materials and mix for 4 - 6 minutes.

[0012] Step 4: Compression molding; Put the uniformly mixed raw materials into a mold for compression molding.

[0013] Step 5: Heat treatment: Put the formed sheet into an electric oven for baking treatment, cool after baking, and check whether there are cracks or bubbles on the surface of the sheet; finally, process the cooled sheet to the required size.

[0014] Using this preparation process of powder-pressed brake discs containing glass fibers, through scientific raw material ratios and optimized technological steps, the comprehensive performance of the brake discs has been significantly improved. In terms of raw materials, barite, alumina, and magnesia are pre-treated by drying and then fully mixed with non-pre-treated raw materials such as steel wool, artificial graphite, foam iron powder, and tire powder. Then, a high-strength glass fiber reinforcement material is added to form a composite formulation system with high hardness, wear resistance, high temperature resistance, and impact resistance. Among them, barite increases the mass inertia, alumina strengthens the surface hardness, magnesia provides heat insulation protection, steel wool enhances the structural strength, artificial graphite improves lubrication and heat dissipation, foam iron powder optimizes the friction performance, tire powder buffers impacts and improves braking smoothness, and glass fiber greatly enhances the overall rigidity and anti-fatigue life. Technologically, the pre-treatment drying is strictly controlled to remove moisture and impurities. In the mixing stage, mixing is carried out in stages to ensure uniform composition. The molding by pressing ensures dimensional accuracy. Heat treatment eliminates internal stresses and detects surface defects. The final product has precise dimensions and a dense structure, with excellent braking stability, wear resistance, and high temperature resistance, effectively extending the service life and enhancing driving safety.

[0015] Furthermore, in step 4, before pressing, the mold is preheated to 80 - 100°C, the pressing temperature is 165°C - 170°C, the pressing pressure is 20 - 25 MPa, and the holding pressure time is 12 - 14 minutes. Preheating the mold to 80 - 100°C before pressing reduces stress concentration caused by temperature gradients and lowers the risk of cracking. Preheating makes the surface temperature of the mold close to the resin softening point, promoting the rapid melting and flowing of the resin in the raw materials at the initial stage of pressing, filling the gaps between fibers and powders, and improving material uniformity.

[0016] Furthermore, in step 5, a stepped heating method is used for heat treatment. The temperature is raised from room temperature to 80°C within 30 minutes, and from 80°C to 120°C within 30 minutes; thereafter, it is heated by 20°C every 30 minutes until it reaches 160°C, and it is held at 160°C for 1.5 - 2.5 hours. Then, it is heated to 180°C within 30 minutes and held at 180°C for 3.5 - 5 hours.

[0017] The thermal expansion coefficients of aramid fiber, glass fiber, and resin matrix differ greatly. The stepped heating can relieve the interfacial stress and enhance the bonding strength between the fiber and the matrix. At the same time, the slow heating avoids the shrinkage or fracture of the fiber due to local overheating, ensuring the uniform dispersion of the reinforcing phase. And it realizes the staged activation of the curing reaction. In the 80 - 120°C stage: Promote the pre-curing of the resin, form a partial cross-linked structure, and enhance the initial strength of the friction plate; in the 120 - 160°C stage: Accelerate the cross-linking of the resin, improve the hardness and rigidity of the material; long-term holding at 180°C: Ensure the complete curing of the resin, form a three-dimensional network structure, and enhance the heat resistance and anti-fatigue performance; thereby ensuring that the curing degree is greater than 95%.

[0018] Further, in step 2, the pre-treated raw materials are dried using a vacuum dryer at a drying temperature of 80 - 100°C for 12 - 15 hours. The boiling point of water decreases in a vacuum environment. For example, the boiling point is 100°C at atmospheric pressure, but it is approximately 45°C at a vacuum of 0.1 MPa, enabling the moisture in the raw materials to rapidly vaporize at a lower temperature. Ordinary drying usually takes 24 - 48 hours, and the drying time is shortened by 40% - 60% compared to ordinary drying. The lower drying temperature reduces energy consumption compared to 120 - 150°C in ordinary drying and simultaneously avoids thermal degradation of heat-sensitive components such as resins and lubricants at high temperatures.

[0019] Further, in step 5, during the sheet cooling, it is slowly cooled in an inert gas atmosphere with a cooling rate less than 5°C / min. Filling the cooling environment with inert gases such as nitrogen and argon can effectively isolate the contact between oxygen and the high-temperature friction plate, avoid the oxidation of metal powder at high temperatures, prevent carbon element burnout or alloy composition segregation. It can avoid problems such as a decrease in friction coefficient and wear resistance caused by oxidation, and ensure the compositional stability of the friction plate after high-temperature sintering. By strictly controlling the cooling rate, the overall temperature gradient of the friction plate is reduced, avoiding thermal stress concentration caused by excessive temperature difference between the inside and outside, and thus preventing cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the process flow chart of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] The following is a further detailed description through specific embodiments:

[0022] Example 1, a formula for a powder-pressed brake disc containing glass fiber, the raw materials include the following components by mass percentage: 16% steel wool, 5% barite, 10% artificial graphite, 5% alumina, 12% phenolic resin, 44% foamed iron powder, 1% tire powder, 5% magnesium oxide, and 2% glass fiber.

[0023] A preparation process for a powder-pressed brake disc containing glass fiber is basically as shown in the appendix Figure 1 and includes the following steps:

[0024] Step 1: Batching; Weigh the raw materials according to the formula and divide the raw materials into pre-treated raw materials, non-pre-treated raw materials, and fiber materials; The pre-treated raw materials include barite, alumina, and magnesium oxide; The non-pre-treated raw materials include steel wool, artificial graphite, phenolic resin, foamed iron powder, and tire powder;

[0025] Step 2: Raw material pre-treatment; Put the pre-treated raw materials into a dryer for drying; Use a vacuum dryer for drying at a drying temperature of 90°C for 14 hours.

[0026] Step 3: Mixing; Put the dried pretreated raw materials and non-pretreated raw materials into a mixer for mixing for 45 minutes; then add fiber materials and mix for 5 minutes. The fiber materials are glass fibers.

[0027] Step 4: Compression molding; Put the evenly mixed raw materials into a mold for compression molding; Preheat the mold to 90 °C before pressing, the pressing temperature is 168 °C, the pressing pressure is 23 MPa, and the pressure holding time is 13 minutes.

[0028] Step 5: Heat treatment: Put the formed sheet into an electric oven for baking treatment, cool after baking and check whether there are cracks or bubbles on the surface of the sheet; Adopt a stepped heating method for heat treatment, the temperature rises from room temperature to 80 °C in 30 minutes, and rises from 80 °C to 120 °C in 30 minutes; Thereafter, the temperature rises by 20 °C every 30 minutes until it rises to 160 °C, and is maintained at 160 °C for 2 hours, then rises to 180 °C in 30 minutes, and is kept warm at 180 °C for 4 hours. Finally, process the cooled sheet to the required size. When the sheet is cooled, it is slowly cooled in an inert gas atmosphere, and the cooling rate is 3 °C / min.

[0029] Example 2, the same parts as in Example 1 will not be described in detail. The differences are as follows: A powder-pressed brake disc formula containing glass fibers, and the raw materials include the following components by mass percentage; 16% steel wool, 5% barite, 10% artificial graphite, 5% alumina, 12% phenolic resin, 44% foam iron powder, 1% tire powder, 5% magnesium oxide, 1.5% glass fiber and 0.5% aramid fiber.

[0030] The steel wool is in the form of short strips with a length of 5-20 mm and a diameter of 10-50 μm, taking into account the dispersibility and long fiber reinforcement effect; Retain a certain aspect ratio, significantly improve the tensile strength and impact resistance of the material. Form a three-dimensional network structure in the matrix to improve the overall performance stability.

[0031] The glass fiber is in the form of powder with a particle size of 30-90 μm, which is easy to be evenly mixed with raw materials such as metal powder and resin, improve the overall strength and heat resistance, and reduce local stress concentration. It has good fluidity during the pressing process and is suitable for filling complex molds. The surface contact area is large, and the bonding strength with the matrix is high.

[0032] A preparation process of a powder-pressed brake disc containing glass fibers, the differences from Example 1 are as follows;

[0033] Step 3: Mixing; Mix the dried pre-treated raw materials barite, alumina, magnesium oxide with the metal powder, foamed iron powder and steel wool in the non-pre-treated raw materials for 20 minutes to ensure the initial combination of the inorganic filler and the metal matrix, at a speed of 350 rpm; add phenolic resin, tire powder and artificial graphite and mix for 15 minutes to form a uniform bonding network, at a speed of 400 rpm; then add glass fiber and aramid fiber and mix for 5 minutes, at a speed of 200 rpm;

[0034] Step 4: Pressing and molding; the uniformly mixed raw materials are placed in a mold for pressing and molding; before pressing, the mold is preheated to 95°C, the pressing temperature is 170°C, the pressing pressure is 25MPa, and the holding time is 10 minutes.

[0035] According to the standard SAE J661-2012, the samples were inspected and the friction coefficients of the samples were tested at room temperature and high temperature. After testing, the friction coefficient of the friction plate at room temperature was 0.381, the friction coefficient at high temperature was 0.393, and the wear rate was 0.0081. The friction coefficient between room temperature and high temperature changes little, and the friction performance of the friction plate has a high stability.

[0036] According to the standard SAE J661-2012, 100 pieces of sample were tested for friction coefficient. The friction coefficient test table was sampled at 10 intervals from 100 sample data. The selected friction data is shown in Table 1 below;

[0037] Table 1 Friction coefficient test data table

[0038] Sample number Frictional force (N) Coefficient of friction μ 1 273 0.406 10 258 0.391 20 281 0.421 30 275 0.418 40 279 0.421 50 250 0.383 60 261 0.401 70 276 0.411 80 255 0.393 90 257 0.391 100 254 0.391

[0039] According to the standard SAE J661-2012, 8 samples were tested. When the samples were worn again, the friction coefficient changed as the temperature gradually increased. The test data results are shown in the following table.

[0040] Table 2 Regrinding decay friction coefficient test data table

[0041] Sample number Frictional force (N) Coefficient of friction μ Temperature (°C) 1 242 0.378 123 2 265 0.392 151 3 273 0.409 177 4 279 0.419 205 5 261 0.391 233 6 253 0.383 265 7 256 0.385 293 8 256 0.385 315

[0042] From the above data, we can see that as the temperature gradually increases, the friction coefficient change curve of the friction plate is relatively gentle, indicating that the friction performance of the friction plate is stable and changes little at high temperatures; thus, it can ensure that during emergency braking of the vehicle, when friction generates high temperatures, the friction plate will not cause a decrease in friction performance due to the high temperature, thus ensuring stable braking.

[0043] The above are only embodiments of the present invention, and common knowledge such as specific structures and characteristics known in the art are not described in detail herein. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicability of the patent. The protection scope required by this application shall be subject to the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. A powder-pressed brake disc formula containing glass fiber, characterized in that: The raw materials include the following components by mass percentage: 14%-18% steel wool, 4%-6% barite, 8%-12% artificial graphite, 4%-6% alumina, 10%-15% phenolic resin, 42%-46% foam iron powder, 0.5%-1.5% tire powder, 4%-6% magnesium oxide and 1%-3% fiber material, and the fiber material includes glass fiber.

2. The powder-pressed brake disc formula containing glass fiber according to claim 1, characterized in that: The fiber material also includes aramid fiber, and the ratio of the aramid fiber to the glass fiber is 1:1-1:

2.

3. The formula of a powder-pressed brake disc containing glass fiber according to claim 1, characterized in that: The raw materials include the following components by mass percentage: 16% steel wool, 5% barite, 10% artificial graphite, 5% alumina, 12% phenolic resin, 44% foam iron powder, 1% tire powder, 5% magnesium oxide and 2% glass fiber.

4. A process for preparing a powder-pressed brake disc containing glass fiber, characterized in that: The steps include: Step 1: batching; weigh the raw materials according to the formula of claim 1, and divide the raw materials into pre-treated raw materials, non-pre-treated raw materials and fiber materials; the pre-treated raw materials include barite, alumina and magnesium oxide; the non-pre-treated raw materials include steel wool, artificial graphite, phenolic resin, foam iron powder, tire powder; Step 2: pre-treating the raw materials; placing the pre-treated raw materials into a dryer for drying; Step 3: Mixing; put the dried pretreated raw materials and non-pretreated raw materials into a mixer and mix them for 35-45 minutes; then add the fiber material and mix for 4-6 minutes; Step 4: Pressing and molding; putting the evenly mixed raw materials into a mold for pressing and molding; Step 5: Heat treatment: Place the formed sheet in an electric oven for baking. After baking, cool it and check whether there are cracks or bubbles on the surface of the sheet. Finally, process the cooled sheet to the required size.

5. The process for preparing a powder-pressed brake disc containing glass fiber according to claim 4, characterized in that: In step 4, the mold is preheated to 80-100° C. before pressing, the pressing temperature is 165° C.-170° C., the pressing pressure is 20-25 MPa, and the holding time is 12-14 minutes.

6. The preparation process of a powder-pressed brake disc containing glass fiber according to claim 4, characterized in that: In step 5, the heat treatment is carried out in a step-by-step heating manner, the temperature is raised from room temperature to 80°C within 30 minutes, and then from 80°C to 120°C within 30 minutes; thereafter, the temperature is raised by 20°C every 30 minutes until it reaches 160°C, and is maintained at 160°C for 1.5-2.5 hours, and then the temperature is raised to 180°C within 30 minutes, and is maintained at 180°C for 3.5-5 hours.

7. The preparation process of a powder-pressed brake disc containing glass fiber according to claim 4 is characterized in that: In the step 2, the pretreated raw material is dried in a vacuum dryer at a temperature of 80-100° C. for 12-15 hours.

8. The preparation process of a powder-pressed brake disc containing glass fiber according to claim 4, characterized in that: In the step 5, the sheet is cooled slowly in an inert gas atmosphere, and the cooling rate is less than 5°C / min.

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