A high-heat-degradation-resistance non-metallic resin-based brake material prepared by using andalusite powder

Abstract

The application discloses a high-heat-recession-resistance non-metallic resin-based braking material prepared from andalusite powder, which is prepared from the following raw materials in parts by weight: andalusite powder 5-25 parts, cashew nut shell oil modified phenolic resin 15-20 parts, bamboo fiber 5-10 parts, aluminum oxide 20-25 parts, barite 12-47 parts, butyronitrile powder 5 parts and graphite 3 parts. The andalusite powder is used to replace copper in the braking material, which is harmful to the environment and has a high cost, so that the non-metallic braking material is realized and the material cost is reduced; the andalusite powder has high-temperature volume stability, and can improve the heat-recession resistance of the friction material, so that the preparation of the braking material from the andalusite powder has important engineering application value and remarkable economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of braking materials, specifically relating to an environmentally friendly, metal-free resin-based braking material with high resistance to thermal fading, prepared using andalusite powder. Background Technology

[0002] With the development of the automotive industry and the increasingly fast pace of life, vehicle speeds are constantly increasing, and the braking system, as a crucial component for driving safety and comfort, has received considerable attention. Braking composite materials, composed of binders, reinforcing fibers, friction modifiers, and fillers, are the braking actuators within the braking system. In recent years, it has been discovered that the wear debris generated by friction materials during braking contains heavy metal components, such as zinc and copper powder. This debris remains suspended in the atmosphere as aerosol particles for extended periods. These inhalable particles can accumulate in the lungs through the respiratory system, posing a significant health hazard. Furthermore, the heavy metal components in the wear debris cause varying degrees of pollution to the atmosphere and rivers. However, copper possesses excellent thermal conductivity and ductility, which are beneficial for improving the thermal fading resistance and frictional wear performance of friction materials. During high-temperature friction, copper can also act as a solid lubricant. Therefore, high thermal fading resistance and minimal or no metal content in braking friction materials have become the focus of research in recent years for novel braking friction materials.

[0003] The patent "A Method for Preparing a Semi-Metallic Brake Pad" (ZL 201610672710.8) uses natural zeolite as raw material. After soaking and freezing in a quaternary ammonium salt solution, the material is ground, pulverized, and calcined. Then, it is immediately immersed in a calcium bicarbonate solution to deposit a layer of calcium carbonate, thus preparing a copper-free semi-metallic brake material with a stable coefficient of friction (0.31-0.33). The patent "Copper-Free Friction Material and Its Preparation Method" (ZL 201410317332.2) uses a combination of carbon fiber and zinc powder to replace copper in the formula to obtain a copper-free brake material with stable braking performance. The patent "A Novel Copper-Free Fiber Composition for Automobile Brake Pads, Its Application and Its Preparation Method" (ZL 201710610855.X) uses a single layer of thermally modified synthetic aluminum fiber to replace copper powder, which rapidly conducts the frictional heat during braking and reduces the occurrence of heat fade. However, the high-temperature friction coefficient and anti-fading performance of the copper-free materials obtained by the above patents are not as good as those of copper-containing brake materials. In addition, other metal elements are added, so the brake materials are not truly metal-free. Furthermore, their anti-fading performance still needs to be further improved.

[0004] Andalusite is an anhydrous aluminosilicate mineral, falling between kaolin refractories with ω(Al2O3)=37% and bauxite refractories with ω(Al2O3)=80-90%, belonging to the medium-aluminum-content aluminosilicate refractories range. Andalusite possesses high-temperature volume stability, melt resistance, and a tendency to transform into mullite, and the raw material itself does not require calcination. Therefore, andalusite materials have excellent application effects in fields requiring high thermal shock resistance and high-temperature strength. Furthermore, compared to copper powder, andalusite powder is much cheaper (one ton of andalusite powder costs approximately 5,000 yuan, while one ton of copper powder costs approximately 95,000 yuan), making its substitution for copper powder a significant economic benefit. In addition, andalusite powder itself has good resistance to thermal fading; its application in brake composite materials can not only reduce environmental pollution from wear debris but also improve the thermal fading resistance of brake composite materials, which is of paramount importance to the green and sustainable development of my country's brake material industry. Summary of the Invention

[0005] The purpose of this invention is to provide a high-heat-fading-resistant, metal-free resin-based braking material that uses andalusite powder as a functional filler to replace copper powder.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A high heat-resistant, non-metallic resin-based braking material prepared using andalusite powder is made from the following raw materials in parts by weight: 5-25 parts andalusite powder, 15-20 parts cashew nut shell oil modified phenolic resin, 5-10 parts bamboo fiber, 20-25 parts alumina, 12-47 parts barite, 5 parts nitrile powder, and 3 parts graphite.

[0008] Furthermore, the andalusite powder has a mesh size of 60-320 mesh.

[0009] The preparation of the resin-based braking material includes the following steps:

[0010] 1) Bamboo fiber processing: The bamboo fiber is cut to obtain bamboo fiber with a length of less than 20mm;

[0011] 2) Drying of raw materials: Cashew shell oil modified phenolic resin and sheared bamboo fiber are dried at 60~70℃ for 40 minutes, nitrile powder is dried at 70℃~80℃ for 30 minutes, andalusite powder, alumina, barite and graphite are dried at 110℃~120℃ for 60 minutes.

[0012] 3) Uniform mixing: Weigh the dried raw materials according to the proportion and put them into the mixer for short-term high-frequency stirring to make the materials uniformly mixed;

[0013] 4) Hot pressing: The mixture obtained in step 3) is placed in a hydraulic press for hot pressing;

[0014] 5) Heat treatment: The hot-pressed sample is placed in an electric heating constant temperature drying oven and heat-treated at 160℃ for 12 hours, and then cooled with the oven to obtain the high heat-resistant metal-free resin-based braking material.

[0015] Furthermore, the total stirring time for the short-term high-frequency stirring described in step 3) is 5 to 8 minutes, and the stirring time for each stirring session does not exceed 10 seconds.

[0016] Furthermore, in step 4), the hot pressing temperature is 165~170℃, the pressure is 10MPa, the holding time is 6min, and the air is vented 2~3 times during the process.

[0017] The resulting resin-based braking material does not contain copper or other heavy metal components that are harmful to the human body. Its coefficient of friction at 300~350℃ is above 0.38 and not lower than the coefficient of friction at 100℃.

[0018] The beneficial effects of this invention are as follows:

[0019] (1) Andalusite powder is an irregular hard powder. Its main components are SiO2 and Al2O3. Its structure is mostly irregular and its surface is relatively rough. It has high hardness. Adding it to brake materials can improve the friction and wear performance of the materials. At the same time, the properties of andalusite powder can enhance its bonding force with resin, which is beneficial to the preparation of materials and the improvement of heat fading resistance.

[0020] (2) The resin-based braking material provided by the present invention does not contain copper or other heavy metal components that are harmful to the human body, and has excellent friction and wear performance, especially its resistance to heat fading is particularly outstanding, which solves the problem of poor high-temperature tribological performance of copper-free braking materials.

[0021] (3) Andalusite powder is relatively inexpensive, and its application in the field of brake materials has important engineering application value and significant economic benefits.

[0022] (4) The present invention uses inorganic non-metallic materials and natural plant fibers to prepare composite materials, and uses andalusite powder to replace copper, so that the resulting braking material has the characteristics of excellent friction coefficient stability, good wear resistance, high strength and low cost. Attached Figure Description

[0023] Figure 1 A three-dimensional response surface model of the effect of changes in the content of andalusite powder and cashew nut shell oil-modified phenolic resin on the friction coefficient in a deterministic screening design experiment at different temperature stages. Detailed Implementation

[0024] As described in the background section, copper has excellent thermal conductivity, which plays a crucial role in the high-temperature friction performance of resin-based braking materials. Andalusite powder, mainly composed of silicon oxide and aluminum oxide, inherently possesses good resistance to thermal fading. Its application in braking composite materials can not only improve the thermal fading resistance of the composite material but also reduce the environmental pollution caused by wear debris. Therefore, this invention aims to obtain a metal-free resin-based braking material with high resistance to thermal fading by replacing copper in braking materials with andalusite powder.

[0025] To investigate the andalusite content and its interaction with resin, reinforcing fibers, and alumina, response surface methodology was used to study their effects on the coefficient of friction. Thirteen experiments were designed using deterministic screening design, and the factors and corresponding levels are shown in Table 1.

[0026] Table 1. Factors and Levels in Deterministic Screening Design

[0027]

[0028] Braking material samples were prepared according to the 13 experimental formulations designed in the deterministic screening design experimental table (the remaining raw materials were barite 12~37 wt%, nitrile powder 5 wt%, graphite 3 wt%, totaling 100 wt%). The friction coefficient of each sample at different temperatures was tested using an X-DM type variable speed friction testing machine. The experimental design and results are shown in Tables 2 and 3.

[0029] Table 2 Deterministic Screening Design Experiment Table

[0030]

[0031] Table 3 Results of Friction Coefficients in Deterministic Screening Design Experiments

[0032]

[0033] A quadratic polynomial regression model in the response surface methodology was used to establish a nonlinear mapping relationship between the content of andalusite powder, cashew nut shell oil-modified phenolic resin, bamboo fiber, and alumina and the friction coefficient of the materials, and a friction coefficient regression model was established. A quantitative model was established between each evaluation index and method parameter using formula (1). Where b0 is a constant; b i b ii and b ij X represents the regression coefficients for the linear, quadratic, and interaction terms, respectively. i and X j Let be the parameters and Y be the evaluation index. The equations are simplified using stepwise regression.

[0034] (1)

[0035] To study the interactions among various factors, combined with the appendix Figure 1 Please provide an explanation. Figure 1 Three-dimensional response surface model diagrams (SFMs) show the effects of changes in the content of andalusite powder (A) and cashew nut shell oil-modified phenolic resin (B) on the friction coefficient at different temperature stages. From the SFM diagrams in (a) and (b), it can be seen that the model trend is steeper along the andalusite powder content direction, while it is relatively gentler along the resin direction. The andalusite powder content is most suitable for the friction coefficient at low temperatures when it is close to the middle value. From the SFM diagram in (c), it can be seen that the model trend is steeper along the andalusite powder content direction, while it is almost horizontal along the resin direction. In this region, the interaction effect on the friction coefficient is mainly reflected in the influence of the andalusite powder content. From the SFM diagram in (d), it can be seen that the trends along the andalusite powder content direction and the resin direction are similar, indicating that the friction coefficient in this region no longer changes significantly with changes in variables. The relatively gentle trend is concentrated in the range where the andalusite powder content and resin content are close to the middle value, and this region is most favorable for the friction coefficient of the sample at 250℃. As can be seen from the 3D response surface model in Figure (e), the model trend is steeper along the direction of andalusite content, while it is relatively gentler along the direction of resin. When the andalusite content is close to the middle value, the friction coefficient of the braking material at 300℃ is most suitable. Similarly, the 3D response surface model in Figure (f) shows that the model trend is also steeper along the direction of andalusite content, while the resin direction is almost horizontal, indicating that the interaction effect on the friction coefficient in this region is mainly reflected in the andalusite content. Therefore, the model trend is steepest in the high and low andalusite content stages, and relatively gentler in the intermediate stage. This suggests that the friction coefficient at 350℃ reaches its peak when the andalusite content is close to the middle value, which is the most suitable content.

[0036] Overall analysis shows that the preferred contents of andalusite powder, cashew nut shell oil modified phenolic resin, bamboo fiber, and alumina are 20%, 20%, 8%, and 20%, respectively.

[0037] The regression coefficient values ​​of the established friction coefficient retrospective model are shown in Table 4.

[0038] Table 4. Regression coefficient values ​​of the friction coefficient regression model

[0039]

[0040] As shown in Table 4, the optimized formulation has a high coefficient of friction and a certain advantage in the stability of the coefficient of friction.

[0041] The technical solution of the present invention will be further described below with reference to specific embodiments. It is obvious that the described embodiments are merely some embodiments of the present invention, and not all embodiments.

[0042] The mesh size of all andalusite powder used is 320 unless otherwise specified.

[0043] Example 1

[0044] 1) Composition of raw materials (by weight)

[0045] 20 parts andalusite powder, 20 parts cashew shell oil modified phenolic resin, 8 parts bamboo fiber, 20 parts alumina, 24 parts barite, 5 parts nitrile powder, and 3 parts graphite.

[0046] 2) Preparation method:

[0047] Bamboo fibers were chopped to obtain 10mm lengths. Cashew nut shell oil-modified phenolic resin and the chopped bamboo fibers were dried at 60℃ for 40 minutes, nitrile powder at 70℃ for 30 minutes, andalusite powder, alumina, barite, and graphite at 120℃ for 60 minutes. The dried raw materials were then mixed according to the designed formula in a mixer for 8 minutes (each mixing time not exceeding 10 seconds) to ensure uniform mixing and a homogeneous powder mixture. The homogeneous mixture was placed in a hydraulic press and hot-pressed at 165-170℃ and 10MPa for 6 minutes, with venting twice during the process. The hot-pressed sample was placed in an electric thermostatic drying oven and heat-treated at 160℃ for 12 hours, followed by furnace cooling to obtain a high-resistance, metal-free resin-based braking material.

[0048] Example 2

[0049] 1) Composition of raw materials (by weight)

[0050] 5 parts andalusite powder, 20 parts cashew nut shell oil modified phenolic resin, 8 parts bamboo fiber, 20 parts alumina, 39 parts barite, 5 parts nitrile powder, and 3 parts graphite.

[0051] 2) Preparation method:

[0052] Bamboo fibers were chopped to obtain 10mm lengths. Cashew nut shell oil-modified phenolic resin and the chopped bamboo fibers were dried at 60℃ for 40 minutes, nitrile powder at 70℃ for 30 minutes, andalusite powder, alumina, barite, and graphite at 120℃ for 60 minutes. The dried raw materials were then mixed according to the designed formula in a mixer for 8 minutes (each mixing time not exceeding 10 seconds) to ensure uniform mixing and a homogeneous powder mixture. The homogeneous mixture was placed in a hydraulic press and hot-pressed at 165-170℃ and 10MPa for 6 minutes, with venting twice during the process. The hot-pressed sample was placed in an electric thermostatic drying oven and heat-treated at 160℃ for 12 hours, followed by furnace cooling to obtain a high-resistance, metal-free resin-based braking material.

[0053] Example 3

[0054] 1) Composition of raw materials (by weight)

[0055] 10 parts andalusite powder, 20 parts cashew nut shell oil modified phenolic resin, 8 parts bamboo fiber, 20 parts alumina, 34 parts barite, 5 parts nitrile powder, and 3 parts graphite.

[0056] 2) Preparation method:

[0057] Bamboo fibers were chopped to obtain 10mm lengths. Cashew nut shell oil-modified phenolic resin and the chopped bamboo fibers were dried at 60℃ for 40 minutes, nitrile powder at 70℃ for 30 minutes, andalusite powder, alumina, barite, and graphite at 120℃ for 60 minutes. The dried raw materials were then mixed according to the designed formula in a mixer for 8 minutes (each mixing time not exceeding 10 seconds) to ensure uniform mixing and a homogeneous powder mixture. The homogeneous mixture was placed in a hydraulic press and hot-pressed at 165-170℃ and 10MPa for 6 minutes, with venting twice during the process. The hot-pressed sample was placed in an electric thermostatic drying oven and heat-treated at 160℃ for 12 hours, followed by furnace cooling to obtain a high-resistance, metal-free resin-based braking material.

[0058] Example 4

[0059] 1) Composition of raw materials (by weight)

[0060] 15 parts andalusite powder, 20 parts cashew shell oil modified phenolic resin, 8 parts bamboo fiber, 20 parts alumina, 29 parts barite, 5 parts nitrile powder, and 3 parts graphite.

[0061] 2) Preparation method:

[0062] Bamboo fibers were chopped to obtain 10mm lengths. Cashew nut shell oil-modified phenolic resin and the chopped bamboo fibers were dried at 60℃ for 40 minutes, nitrile powder at 70℃ for 30 minutes, andalusite powder, alumina, barite, and graphite at 120℃ for 60 minutes. The dried raw materials were then mixed according to the designed formula in a mixer for 8 minutes (each mixing time not exceeding 10 seconds) to ensure uniform mixing and a homogeneous powder mixture. The homogeneous mixture was placed in a hydraulic press and hot-pressed at 165-170℃ and 10MPa for 6 minutes, with venting twice during the process. The hot-pressed sample was placed in an electric thermostatic drying oven and heat-treated at 160℃ for 12 hours, followed by furnace cooling to obtain a high-resistance, metal-free resin-based braking material.

[0063] Example 5

[0064] 1) Composition of raw materials (by weight)

[0065] 25 parts andalusite powder, 20 parts cashew nut shell oil modified phenolic resin, 8 parts bamboo fiber, 20 parts alumina, 19 parts barite, 5 parts nitrile powder, and 3 parts graphite.

[0066] 2) Preparation method:

[0067] Bamboo fibers were chopped to obtain 10mm lengths. Cashew nut shell oil-modified phenolic resin and the chopped bamboo fibers were dried at 60℃ for 40 minutes, nitrile powder at 70℃ for 30 minutes, andalusite powder, alumina, barite, and graphite at 120℃ for 60 minutes. The dried raw materials were then mixed according to the designed formula in a mixer for 8 minutes (each mixing time not exceeding 10 seconds) to ensure uniform mixing and a homogeneous powder mixture. The homogeneous mixture was placed in a hydraulic press and hot-pressed at 165-170℃ and 10MPa for 6 minutes, with venting twice during the process. The hot-pressed sample was placed in an electric thermostatic drying oven and heat-treated at 160℃ for 12 hours, followed by furnace cooling to obtain a high-resistance, metal-free resin-based braking material.

[0068] Example 6

[0069] 1) Composition of raw materials (by weight)

[0070] 20 parts andalusite powder (60 mesh), 20 parts cashew shell oil modified phenolic resin, 8 parts bamboo fiber, 20 parts alumina, 24 parts barite, 5 parts nitrile powder, and 3 parts graphite.

[0071] 2) Preparation method:

[0072] Bamboo fibers were chopped to obtain 10mm lengths. Cashew nut shell oil-modified phenolic resin and the chopped bamboo fibers were dried at 60℃ for 40 minutes, nitrile powder at 70℃ for 30 minutes, andalusite powder, alumina, barite, and graphite at 120℃ for 60 minutes. The dried raw materials were then mixed according to the designed formula in a mixer for 8 minutes (each mixing time not exceeding 10 seconds) to ensure uniform mixing and a homogeneous powder mixture. The homogeneous mixture was placed in a hydraulic press and hot-pressed at 165-170℃ and 10MPa for 6 minutes, with venting twice during the process. The hot-pressed sample was placed in an electric thermostatic drying oven and heat-treated at 160℃ for 12 hours, followed by furnace cooling to obtain a high-resistance, metal-free resin-based braking material.

[0073] Example 7

[0074] 1) Composition of raw materials (by weight)

[0075] 20 parts andalusite powder (200 mesh), 20 parts cashew shell oil modified phenolic resin, 8 parts bamboo fiber, 20 parts alumina, 24 parts barite, 5 parts nitrile powder, and 3 parts graphite.

[0076] 2) Preparation method:

[0077] Bamboo fibers were chopped to obtain 10mm lengths. Cashew nut shell oil-modified phenolic resin and the chopped bamboo fibers were dried at 60℃ for 40 minutes, nitrile powder at 70℃ for 30 minutes, andalusite powder, alumina, barite, and graphite at 120℃ for 60 minutes. The dried raw materials were then mixed according to the designed formula in a mixer for 8 minutes (each mixing time not exceeding 10 seconds) to ensure uniform mixing and a homogeneous powder mixture. The homogeneous mixture was placed in a hydraulic press and hot-pressed at 165-170℃ and 10MPa for 6 minutes, with venting twice during the process. The hot-pressed sample was placed in an electric thermostatic drying oven and heat-treated at 160℃ for 12 hours, followed by furnace cooling to obtain a high-resistance, metal-free resin-based braking material.

[0078] Comparative Example

[0079] 1) Composition of raw materials (by weight)

[0080] 25 parts copper powder, 20 parts cashew shell oil modified phenolic resin, 8 parts bamboo fiber, 20 parts alumina, 19 parts barite, 5 parts nitrile powder, and 3 parts graphite.

[0081] 2) Preparation method:

[0082] Bamboo fibers were chopped to obtain 10mm lengths. Cashew nut shell oil-modified phenolic resin and the chopped bamboo fibers were dried at 60℃ for 40 minutes, nitrile powder at 70℃ for 30 minutes, andalusite powder, alumina, barite, and graphite at 120℃ for 60 minutes. The dried raw materials were then mixed according to the designed formula in a mixer for 8 minutes (each mixing time not exceeding 10 seconds) to ensure uniform mixing and a homogeneous powder mixture. The homogeneous mixture was placed in a hydraulic press and hot-pressed at 165-170℃ and 10MPa for 6 minutes, with venting twice during the process. The hot-pressed sample was placed in an electric thermostatic drying oven and heat-treated at 160℃ for 12 hours, followed by furnace cooling to obtain the copper-containing resin-based braking material.

[0083] The brake material samples prepared in Examples 1-7 and the comparative examples were tested for friction and wear performance on an X-DM type variable speed friction testing machine. According to the requirements of Class IV disc brake linings in the national standard for disc brake linings (GB5763-2008), the friction coefficient and wear rate were measured at disc temperatures of 100℃, 150℃, 200℃, 250℃, 300℃ and 350℃ during the heating process, after 5000 revolutions of friction. The results are shown in Tables 5 and 6, respectively.

[0084] Table 5. Test results of friction coefficients for different samples

[0085]

[0086] Table 6 Wear rate test results for different samples

[0087]

[0088] According to the test results of friction coefficient and wear rate in Tables 5 and 6, it can be found that the friction coefficient and wear rate of the brake materials prepared in the examples are both within the allowable range of the national standard, with Example 1 showing the best performance. Furthermore, compared with the copper-containing resin-based brake materials prepared in the comparative examples, the brake materials prepared using andalusite powder to replace copper exhibit significantly higher resistance to thermal fading. This proves that the method of the present invention can solve the problems of copper-free and high resistance to thermal fading in brake materials, which is of great significance to the green and sustainable development of my country's brake material industry.

[0089] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A metal-free resin-based braking material with high resistance to thermal fading, prepared using andalusite powder, characterized in that, The resin-based braking material is made from the following raw materials in parts by weight: 5-25 parts andalusite powder, 15-20 parts cashew nut shell oil modified phenolic resin, 5-10 parts bamboo fiber, 20-25 parts alumina, 12-47 parts barite, 5 parts nitrile powder, and 3 parts graphite.

2. The high heat-resistant, non-metallic resin-based braking material prepared using andalusite powder according to claim 1, characterized in that, The andalusite powder has a mesh size of 60-320.

3. The high heat-resistant, non-metallic resin-based braking material prepared using andalusite powder according to claim 1, characterized in that, The preparation of the resin-based braking material includes the following steps: 1) Bamboo fiber processing: The bamboo fiber is cut to obtain bamboo fiber with a length of less than 20mm; 2) Drying of raw materials: Cashew shell oil modified phenolic resin and sheared bamboo fiber are dried at 60~70℃ for 40 minutes, nitrile powder is dried at 70℃~80℃ for 30 minutes, andalusite powder, alumina, barite and graphite are dried at 110℃~120℃ for 60 minutes. 3) Uniform mixing: Weigh the dried raw materials according to the proportion and stir them at a high frequency for a short time to ensure that the materials are mixed evenly; 4) Hot pressing: The mixed material obtained in step 3) is hot pressed into shape; 5) Heat treatment: The hot-pressed sample is heat-treated at 160℃ for 12 hours and then cooled in the furnace to obtain the high heat-resistant metal-free resin-based braking material.

4. The high heat-resistant, non-metallic resin-based braking material prepared using andalusite powder according to claim 3, characterized in that, The total stirring time for the short-term high-frequency stirring described in step 3) is 5 to 8 minutes, and the stirring time for each stirring session shall not exceed 10 seconds.

5. The high heat-resistant, non-metallic resin-based braking material prepared using andalusite powder according to claim 3, characterized in that, The hot pressing temperature in step 4) is 165~170℃, the pressure is 10MPa, the holding time is 6min, and the air is vented 2~3 times during the process.

6. The high heat-resistant, non-metallic resin-based braking material prepared using andalusite powder according to claim 1, characterized in that, The resin-based braking material has a friction coefficient of 0.38 or higher at 300-350°C and is not lower than the friction coefficient at 100°C.

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