Non-dense carbon-ceramic friction material, and preparation method therefor and use thereof

Abstract

The present invention relates to the field of carbon-ceramic composite materials, in particular to a non-dense carbon-ceramic friction material, and a preparation method therefor and the use thereof. The non-dense carbon-ceramic friction material is obtained by subjecting a C / C-Si green body to a silicon infiltration treatment using silicon powder. The raw materials for preparing the C / C-Si green body comprise chopped carbon fibers, graphite powder, a ferrosilicon mixture, silicon carbide powder, boron nitride powder, and phenolic resin powder. The non-dense carbon-ceramic friction material is made to have a porosity of 15-25 vol.%, a high-temperature resistance limit of 1350°C and a compressive strength of 80.5 ± 2.4  MPa; therefore, a friction plate prepared therefrom exhibits a wear amount of 52.8-95.0  μm and a friction coefficient of 0.6-0.7 in an AK master program test. Compared with friction materials in the prior art, the non-dense carbon-ceramic friction material has the advantages of a non-dense structure, a light weight, high-temperature resistance, etc.

Description

A non-dense carbon ceramic friction material, its preparation method and application Technical Field

[0001] This invention relates to the field of carbon-ceramic composite materials, and more particularly to a non-dense carbon-ceramic friction material, its preparation method, and its application. Background Technology

[0002] Various transportation vehicles, such as automobiles and high-speed trains, have increasingly higher requirements for their braking systems to achieve reliable braking in high-speed, heavy-load, and complex environments. This places more stringent demands on the temperature resistance limit, friction and wear performance, and stability of braking friction materials, while also requiring materials to be lightweight to achieve weight reduction.

[0003] Existing friction pad materials include resin-based friction materials, powder metallurgy friction materials, and dense carbon ceramic materials. However, these materials have different defects when matched with brake discs, resulting in limitations in the application of the friction pads.

[0004] In the existing technology, most carbon ceramic brake discs are matched with resin-based friction pads. However, resin-based friction materials will decompose at temperatures above 400°C. At the same time, the surface of the friction pads may be dull, not shiny, and loose, with large waste edges. Hot-pressed semi-finished products may have cracks, blistering, delamination, etc., causing the performance of the friction pads to deteriorate.

[0005] Powder metallurgy friction pads are made by mixing, pressing, and sintering metal-based powdered materials at high temperatures. Currently, they have only been tested and researched in high-speed train applications. When matched with carbon-ceramic brake discs, their weight is significant, hindering weight reduction and limiting practical applications. The melting point of the Cu matrix is ​​only 1083℃, limiting the long-term service temperature of the friction pads to below 800℃, making them unsuitable for extreme working conditions.

[0006] Dense carbon-ceramic friction materials have a porosity of less than 8 vol.% and can currently serve for extended periods at temperatures above 1000°C. However, as friction pad materials, they also suffer from technical problems such as unstable friction performance and insufficient wear resistance. For example, in Fig. 4 of the paper "Full-ceramic brake systems for high-performance friction applications" published in the Journal of the European Ceramic Society, authors Nico Langhof et al. concluded that the friction coefficient stability of carbon-ceramic friction pads C / SiC SF and C / SiC SF 11Coke is not as good as that of resin-based friction pads Low Met. Fig. 10 shows that dense carbon-ceramic friction pads, C / SiC SF (which is made of the same material as carbon-ceramic brake discs), and C / SiC SF 11Coke (modified with coke) all have greater wear than resin-based friction pads (Low Met). For example, in the journal *Tribol Lett*, authors Gen Li et al., in Fig. 2 of the paper *Comparison of Friction and Wear Behavior Between C / C, C / C-SiC and Metallic Composite Materials*, concluded that the friction coefficient stability of carbon-ceramic friction pads (C / C-SiC) is not as good as that of metal-based friction pads (metallic), and in Fig. 3, they concluded that the wear rate of carbon-ceramic friction pads (C / C-SiC) is greater than that of metal-based friction pads (metallic). Even though CN117024152A discloses a low-cost carbon-ceramic brake material and its preparation method, which improves existing carbon-ceramic materials by cutting carbon fibers to obtain short fibers, mixing the short fibers, calcined petroleum coke, phenolic resin, hexamethylenetetramine, nano-zirconium silicate powder, and vermiculite powder to obtain a mixture, pressing the mixture into a blank, carbonizing the blank to obtain a carbonized blank, react-infiltrating the carbonized blank with silicon to obtain a carbon-ceramic blank, further removing impurities with silicon, and finally polishing, the carbon-ceramic brake material is obtained. This technical solution includes a silicon impurity removal step, where the silicon liquid reacts and deposits on the surface during precipitation to form a uniform, dense silicon carbide layer. However, if this is used to prepare a friction pad for friction with a brake disc, the uniform, dense silicon carbide layer on its surface still cannot overcome the technical problem of poor adjustment in traditional dense friction pads and brake discs during friction. Furthermore, petroleum coke is amorphous carbon, and due to its complex composition, its properties are affected by factors such as ash, sulfur, and volatile matter, resulting in numerous defects in its microstructure. These defects may be difficult to completely eliminate during calcination, thus affecting the performance of the final product. Currently, there are no reports on non-dense carbon-ceramic composite materials.

[0007] Based on the above, the existing technology has technical problems that urgently need to be solved, such as the inability of the materials used to prepare friction plates to simultaneously meet the requirements of being lightweight, high-strength, high-temperature resistant, having low wear, stable friction performance, and adapting to extreme working conditions. Summary of the Invention

[0008] To solve the above-mentioned technical problems, the present invention provides a non-dense carbon ceramic friction material, wherein the non-dense carbon ceramic friction material is obtained by silicon infiltration treatment of C / C-Si preform with silicon powder, and the raw materials for preparing C / C-Si preform include short-cut carbon fibers, graphite powder, silicon-iron mixture, silicon carbide powder (SiC powder), boron nitride powder (BN powder), and phenolic resin powder.

[0009] The non-dense carbon ceramic friction material has a porosity of 15-25 vol.%; a high temperature limit of 1350℃; and a compressive strength of 80.5 ± 2.4 MPa.

[0010] Furthermore, the density of the non-dense carbon ceramic friction material is 1.8-2.2 g / cm³. 3 .

[0011] Furthermore, the components and proportions of the raw materials for preparing the C / C-Si preform, by weight, are as follows:

[0012] Short-cut carbon fiber: 15-35%;

[0013] Graphite powder: 5-10%;

[0014] Ferrosilicon mixture: 30-50%;

[0015] Silicon carbide powder (SiC powder): 5-10%;

[0016] Boron nitride powder (BN powder): 3-8%;

[0017] Phenolic resin powder: 15-30%.

[0018] Furthermore, the volume content of silicon carbide in the overall non-dense carbon ceramic friction material is 15-30%.

[0019] Furthermore, the pore diameter of the non-dense carbon ceramic friction material is 10-200 μm.

[0020] Furthermore, the mass ratio of the C / C-Si preform to the silicon powder is 1:2.

[0021] Furthermore, the chopped carbon fiber has a length of 3-6 mm and is composed of one or more chopped carbon fibers of different lengths, and the carbon content of the chopped carbon fiber is ≥95 wt.%.

[0022] Furthermore, the chopped carbon fiber is a product made by cutting carbon fiber filaments short using a fiber cutting machine.

[0023] Furthermore, the carbon fiber filament also includes carbon fiber prepreg obtained by modifying the carbon fiber filament, such as carbon fiber prepreg obtained by prepregping the carbon fiber filament with resin.

[0024] Furthermore, the graphite powder has a particle size of 150 mesh and a carbon content of ≥96 wt.%.

[0025] Furthermore, the ferrosilicon mixture is one or more Fe-Si alloy powders of the standard grade ferrosilicon specified in GB / T 2272-2020, or a mixture of ferrosilicon powder with any proportion of Si powder.

[0026] Furthermore, the Fe-Si alloy powder is one or more of FeSi40, FeSi65, FeSi75, and FeSi90.

[0027] Furthermore, the particle size of the ferrosilicon mixture is 150-350 mesh.

[0028] Furthermore, the particle size of the silicon carbide powder (SiC powder) is 200-300 mesh.

[0029] Furthermore, the particle size of the boron nitride powder (BN powder) is 800-1000 mesh.

[0030] Furthermore, the phenolic resin powder is a thermosetting phenolic resin powder with a particle size of 400-600 mesh.

[0031] Furthermore, the silicon powder has a particle size of 100-150 mesh and a silicon purity of ≥99 wt.%.

[0032] This invention provides a method for preparing a non-dense carbon ceramic friction material, comprising the following steps:

[0033] Step 1: Weigh the short-cut carbon fibers, graphite powder, ferrosilicon alloy powder, silicon carbide powder (SiC powder), boron nitride powder (BN powder), and phenolic resin powder, and mix them to obtain a mixed powder.

[0034] Step 2: Heat, press, and solidify the mixed powder from Step 1 to obtain a raw blank;

[0035] Step 3: Carbonize the green blank obtained in Step 2 to obtain a C / C-Si green body;

[0036] Step 4: The C / C-Si preform obtained in Step 3 is subjected to melt silicon infiltration treatment with silicon powder to obtain the non-dense carbon ceramic friction material.

[0037] Furthermore, in step 1, a dual-motion mixer is used to mix the raw materials at room temperature for 20-60 minutes.

[0038] The purpose of using a dual-motion mixer is twofold: firstly, it achieves more uniform mixing compared to a V-type mixer (which mixes materials solely by rotating a drum); and secondly, it prevents short-cut carbon fibers from becoming coated with powder and forming balls during the mixing process.

[0039] Further, the specific steps in step 2 are as follows: the mixed powder is filled into a metal mold, the metal mold is placed between the upper and lower pressure plates of a flat vulcanizing machine, the upper and lower pressure plates of the flat vulcanizing machine are heated to 80°C and kept at that temperature for 5-30 minutes to preheat and keep the metal mold and mixed powder at that temperature; after the temperature is kept at that temperature, the upper and lower pressure plates of the flat vulcanizing machine are heated to 180°C, and a pressure of 20MPa is applied to the metal mold to liquefy the phenolic resin powder and bond the remaining powder. After keeping the temperature and pressure for 20-30 minutes, the pressure is released to normal pressure, and the upper and lower pressure plates are stopped heating. The mold is allowed to cool naturally to room temperature and the phenolic resin is allowed to solidify. The sample is then demolded and removed to obtain a green blank.

[0040] Furthermore, the metal mold can be any shape depending on actual needs, such as a cylindrical mold or a friction plate-shaped mold.

[0041] Further, the specific steps of carbonization in step 3 are as follows: after evacuating to a vacuum degree of 10 Pa, nitrogen gas is introduced into the furnace to expel air, and then the temperature is raised to 900℃ at a rate of 1-5℃ / min and held for 0.5-3h. During the heating and holding process, nitrogen gas is continuously introduced to maintain the pressure inside the furnace at 0-0.04MPa. After the holding is completed, heating is stopped, and after waiting for the temperature inside the furnace to drop to 300℃, nitrogen gas is stopped. The furnace temperature is then allowed to cool to room temperature, and the sample is removed to obtain the C / C-Si billet.

[0042] Furthermore, in step 3, under conditions of isolation from air and high temperature, the phenolic resin decomposes, and the hydrogen and oxygen elements are removed to form volatile products such as hydrogen, oxidation, and water, which are discharged from the system sample, while the remaining carbon elements are retained in the C / C-Si preform.

[0043] Further, the specific steps of silicon infiltration in step 4 are as follows: Prepare silicon powder, spread the silicon powder at the bottom of a graphite crucible, and place the C / C-Si blank obtained in step 3 on top of the silicon powder; place the graphite crucible in a high-temperature furnace, evacuate the furnace, and raise the furnace temperature to 1500-1700℃ at a rate of 5℃ / min, and hold for 1-2 hours. During this period, the silicon powder melts into liquid silicon. Under vacuum, the liquid silicon enters the interior of the C / C-Si blank through the pores or contacts the surface of the C / C-Si blank. Part of it reacts with the C in the C / C-Si blank to form SiC, while the unreacted liquid silicon is also retained in the pores or on the surface; after the holding time is completed, stop heating and wait for the furnace temperature to drop to room temperature. Then, take out the silicon-infiltrated blank material to obtain a non-dense carbon ceramic friction material.

[0044] Furthermore, the mass of the silicon powder is twice the mass of the C / C-Si preform in step 3.

[0045] The present invention also provides a friction pad, which is made of the above-mentioned non-dense carbon ceramic friction material;

[0046] The wear of the friction plate in the AK-master program test was 52.8-95.0 μm; the coefficient of friction was 0.6-0.7.

[0047] Furthermore, when preparing the non-dense carbon ceramic friction material, the shape of the mold used matches the shape of the friction plate.

[0048] The present invention also provides a braking device, the braking device comprising the above-described friction pad.

[0049] Furthermore, the braking device also includes a brake disc.

[0050] Furthermore, the brake disc is a carbon ceramic brake disc.

[0051] Furthermore, the braking device also includes calipers, brake lines, and connectors.

[0052] The present invention also provides an automobile, the automobile including the above-described braking device.

[0053] The present invention also provides an aircraft including the above-described braking device.

[0054] The present invention also provides a high-speed railway, which includes the above-mentioned braking device.

[0055] The beneficial effects of this invention are as follows:

[0056] 1. The non-dense carbon ceramic friction material prepared by the present invention is obtained by silicon infiltration treatment of C / C-Si preform with silicon powder. The raw materials for preparing the C / C-Si preform include short carbon fibers, graphite powder, silicon-iron mixture, silicon carbide powder (SiC powder), boron nitride powder (BN powder), and phenolic resin powder.

[0057] Compared to existing friction materials (such as resin-based friction materials, metal-based powder metallurgy materials, or dense carbon ceramic materials), it has the following advantages:

[0058] Non-dense: The non-dense carbon ceramic friction material prepared by this invention has a porosity of 15-25 vol.%. Existing carbon ceramic materials are made by weaving carbon fibers into a preform to form a carbon-carbon composite material with micron-sized pores, and then performing silicon infiltration densification through saturated melt infiltration. However, the amount of pores filled in the carbon-carbon composite material during the melt infiltration process is relatively uncontrollable, and densification can only be achieved through saturated infiltration. The final carbon ceramic material obtained is nearly dense with a porosity of less than 8 vol.%. This invention utilizes a specific powder particle size to first obtain a C / C-Si preform with large-sized pores. At the same time, combined with a specific formula and ratio, an interaction interface is generated, which prevents the pores from being completely filled during the silicon infiltration process, thus obtaining the non-dense carbon ceramic friction material with a specific porosity of this invention.

[0059] Lightweight: The average density of non-dense carbon ceramic friction materials is 1.8-2.2 g / cm³. 3 Its density is less than that of resin-based friction materials, and only 1 / 3 to 1 / 2 of the density of metal-based powder metallurgy materials;

[0060] High temperature resistance: The temperature resistance limit can reach 1350℃, which is much higher than the temperature resistance limit of 400℃ for resin-based friction materials and 800℃ for metal-based powder metallurgy materials.

[0061] 2. When the non-dense carbon ceramic friction material of the present invention is prepared into a friction pad and matched with an existing ordinary dense carbon ceramic brake disc, it has the following advantages compared with existing friction pads:

[0062] Low wear: The friction pads prepared by the non-dense carbon ceramic material of the present invention were tested by AK-master program on an inertial scale test bench. After the test, the wear of the friction pads was 52.8-95.0μm. Under the same conditions, the wear of friction pads prepared by metal-based powder metallurgy materials and resin-based friction materials was 185.7μm and 534.4μm, respectively.

[0063] High porosity: A porosity of 15-25 vol.% ensures that the prepared friction pad has uniform pores on the surface and inside. Compared with the existing technology such as the carbon ceramic material with a uniform and dense silicon carbide layer on the surface disclosed in CN117024152A, the friction pad prepared by the present invention has pores evenly distributed on the surface and inside of the material that can trap hard abrasive particles during braking, effectively alleviating the typical abrasive wear phenomenon of the friction pad during braking friction and significantly reducing the amount of material wear.

[0064] Stable coefficient of friction: Braking tests were conducted using the AK-master testing program. During the thermal decay stage, the friction pads made of non-dense carbon ceramic materials did not experience thermal decay in the coefficient of friction when matched with ordinary dense carbon ceramic brake discs, and the coefficient of friction remained stable between 0.6 and 0.7. The coefficient of friction of metal-based powder metallurgy friction pads ranged from 0.5 to 0.7; the coefficient of friction of resin-based friction pads ranged from 0.3 to 0.5; and the coefficient of friction of high-density carbon ceramic friction pads ranged from 0.6 to 0.9. The range of the coefficient of friction is larger than that of the friction pads prepared in this invention, and is not stable enough.

[0065] Short process cycle: Traditionally, chemical vapor deposition is used to densify and obtain high-density carbon ceramic materials, with a total process cycle of up to three months. This invention uses a short-cut carbon fiber mixing, molding and carbonization process to obtain C / C-Si preforms, and finally melt-infiltrates silicon to obtain non-dense carbon ceramic friction materials. The total process time is shortened to within 7 days, which significantly shortens the process time and can improve production efficiency.

[0066] 3. The graphite powder introduced in the raw materials of this invention exists in the non-dense carbon ceramic friction material. As a material for preparing friction plates, the graphite powder in the material plays a lubricating effect when it rubs against the brake disc during braking. Compared with the use of petroleum coke in the prior art, it is more conducive to stabilizing the friction coefficient and reducing wear.

[0067] 4. Since the non-dense carbon ceramic friction material prepared by this invention can reach a temperature limit of 1350℃, it can be made into friction pads to achieve operation under extreme conditions, i.e., temperatures above 1300℃. This allows the corresponding braking device to be applied in high-speed trains such as the CR 450 EMU. In emergency braking, the braking temperature of the EMU can reach 1200℃. However, if metal-based powder metallurgy materials with a high temperature limit of 800℃ or resin-based friction materials with a high temperature limit of 400℃ are used, they will definitely melt and stick together, causing the EMU to be unable to operate.

[0068] 5. Due to its specific properties and structure, the non-dense carbon ceramic friction material prepared by this invention can be widely used in automobiles, airplanes, high-speed rail, large braking equipment and other fields. More specifically, it can be used in the wheel brake discs of fixed-wing UAVs, skids of magnetic levitation trains, rotor brakes of helicopters, yaw brakes of wind turbines, brakes of large cranes at docks, and brakes of special military vehicles. Attached Figure Description

[0069] Figure 1 is a SEM image of the non-dense carbon ceramic friction material of the present invention;

[0070] Figure 2 is a thermal decay braking curve of the non-dense carbon ceramic friction material in Embodiment 1 of the present invention;

[0071] Figure 3 shows the thermal decay braking curve of the metal-based powder metallurgy material in Comparative Example 1.

[0072] Figure 4 shows the thermal decay braking curve of the resin-based friction material in Comparative Example 2.

[0073] Figure 5 shows the thermal decay braking curve of the high-density carbon ceramic material in Comparative Example 3.

[0074] Figure 6 shows the thermal decay braking curve of the carbon ceramic friction material prepared in Comparative Example 4 after replacing the graphite powder in Example 1 with petroleum coke. Detailed Implementation

[0075] In the following embodiments, the density and porosity were tested using the drainage method, with the testing standard being GB / T 24529-2009; the compressive strength was tested according to ISO 14544-2013. To ensure the reliability of the experimental results, the brake discs used in the embodiments and comparative examples of this invention were conventional dense carbon ceramic brake discs made of the same material.

[0076] Example 1

[0077] This embodiment provides a non-dense carbon ceramic friction material, the preparation method of which includes the following steps:

[0078] Step 1: Weigh 25% of short-cut carbon fibers with a length range of 3-6mm, 5% of graphite powder, 40% of FeSi75, 5% of silicon carbide powder, 5% of boron nitride powder, and 20% of phenolic resin powder according to the weight ratio. Mix the above raw materials at room temperature using a dual-motion mixer for 30 minutes to obtain a mixed powder.

[0079] Wherein, the carbon content of the short-cut carbon fiber is ≥95wt.%;

[0080] The graphite powder has a particle size of 150 mesh and a carbon content of ≥96 wt.%.

[0081] The FeSi75 has a particle size of 300 mesh;

[0082] The silicon carbide powder has a particle size of 200 mesh;

[0083] The boron nitride powder has a particle size of 800 mesh;

[0084] The phenolic resin powder is a thermosetting phenolic resin powder with a particle size of 400 mesh.

[0085] Step 2: Heat, press, and solidify the mixed powder from Step 1 to obtain a raw blank;

[0086] Specifically, the mixed powder is filled into a cylindrical metal mold, which is then placed between the upper and lower plates of a flat vulcanizing machine. The upper and lower plates of the flat vulcanizing machine are heated to 80°C and held for 10 minutes to liquefy the phenolic resin powder and bind the remaining powder. After the holding time is completed, the upper and lower plates of the flat vulcanizing machine are heated to 180°C, and a pressure of 20 MPa is applied to the mold. The pressure is maintained for 20 minutes, and then the pressure is released. At the same time, the heating of the upper and lower plates is stopped, and the mold is allowed to cool naturally to room temperature to cure the phenolic resin. The sample is then demolded to obtain a green blank.

[0087] Step 3: Carbonize the green blank obtained in Step 2 to obtain a C / C-Si green body;

[0088] Specifically, after evacuating to a vacuum level of 10 Pa, nitrogen gas is introduced into the furnace, and the temperature is raised to 900 °C at a rate of 2 °C / min. The temperature is held for 2 hours, and nitrogen gas is continuously introduced during the heating and holding process to maintain the furnace pressure at 0-0.04 MPa. After the holding period, heating is stopped, and the furnace temperature is allowed to drop to 300 °C before nitrogen gas introduction is stopped. The furnace temperature is then allowed to cool to room temperature, and the sample is removed to obtain the C / C-Si billet.

[0089] Step 4: The C / C-Si preform obtained in Step 3 is subjected to silicon infiltration treatment with silicon powder to obtain the non-dense carbon ceramic friction material; the silicon powder has a particle size of 100 mesh and a silicon purity of ≥99wt.%.

[0090] Specifically, prepare silicon powder with a weight twice that of the C / C-Si billet obtained in step 3, spread the silicon powder at the bottom of a graphite crucible, and place the C / C-Si billet obtained in step 3 on top of the silicon powder; place the graphite crucible in a high-temperature furnace, evacuate the furnace, and raise the furnace temperature to 1600℃ at a rate of 5℃ / min, and hold for 1 hour; after the holding period, stop heating and wait for the furnace temperature to drop to room temperature, then take out the silicon-infiltrated billet material to obtain a non-dense carbon ceramic friction material.

[0091] The total process time for preparing the non-dense carbon ceramic friction material in this embodiment is 7 days.

[0092] The average density of the non-dense carbon ceramic friction material prepared in this embodiment is 2.0 g / cm³. 3 Porosity is 20 vol.%; maximum high temperature resistance is 1350℃; compressive strength is 80.5 MPa.

[0093] The silicon carbide volume content in the overall non-dense carbon ceramic friction material is 24%.

[0094] In this embodiment, the SEM image of the non-dense carbon ceramic friction material is shown in Figure 1. Pores are dispersed in the material, with pore sizes ranging from 10 to 200 μm. The light gray area is a granular Fe-Si alloy phase. The SiC introduced during the silicon infiltration process constitutes the skeleton of the material. Carbon fibers, graphite, and boron nitride are dispersed in the material.

[0095] By replacing the metal mold shape in the preparation method of this embodiment with a mold shaped like a friction pad, a friction pad using the non-dense carbon-ceramic friction material of this embodiment was prepared. Braking tests were conducted using the AK-master testing program to obtain the thermal fade braking curve. Specifically, the temperature was gradually increased to 550℃ for high-temperature thermal fade testing, with a total of 15 uninterrupted braking tests performed. Braking was initiated at 100 km / h with a 40% deceleration until the speed decreased to 5 km / h. The corresponding thermal fade braking curve is shown in Figure 2. The blue curve (μ) represents the instantaneous change in the friction coefficient of the brake disc and friction pad from the start to the end of each braking process; the pink dot (μ) represents the average friction coefficient record for one braking operation; the red curve (T) represents the corresponding braking temperature, i.e., the temperature rises immediately after the end of one braking operation and the start of the next; the gray curve (P) corresponds to the braking pressure. It can be seen that the friction performance (average friction coefficient, braking pressure) of the non-dense carbon-ceramic friction material prepared in this embodiment remains essentially unchanged after the braking temperature is increased. In other words, the aforementioned properties of the non-dense carbon-ceramic friction material prepared by this invention remained basically stable during 15 consecutive uninterrupted braking tests, unaffected by factors such as temperature. In the AK-master program test, the wear of the friction pad was 77.1 μm; the coefficient of friction remained stable between 0.6 and 0.7, with no thermal decay of the coefficient of friction; simultaneously, the wear of the carbon-ceramic brake disc used in the test was 9 μm.

[0096] Example 2

[0097] This embodiment provides a non-dense carbon ceramic friction material, the preparation method of which includes the following steps:

[0098] Step 1: Weigh 20% of short-cut carbon fibers with a length range of 3-6mm, 10% of graphite powder, 30% of FeSi40, 10% of silicon carbide powder, 8% of boron nitride powder, and 22% of phenolic resin powder according to the weight ratio. Mix the above raw materials at room temperature using a dual-motion mixer for 40 minutes to obtain a mixed powder.

[0099] Wherein, the carbon content of the short-cut carbon fiber is ≥95wt.%;

[0100] The graphite powder has a particle size of 150 mesh and a carbon content of ≥96 wt.%.

[0101] The FeSi40 has a particle size of 300 mesh;

[0102] The silicon carbide powder has a particle size of 300 mesh;

[0103] The boron nitride powder has a particle size of 800 mesh;

[0104] The phenolic resin powder is a thermosetting phenolic resin powder with a particle size of 600 mesh.

[0105] Step 2: Heat, press, and solidify the mixed powder from Step 1 to obtain a raw blank;

[0106] Specifically, the mixed powder is filled into a cylindrical metal mold, which is then placed between the upper and lower plates of a flat vulcanizing machine. The upper and lower plates of the flat vulcanizing machine are heated to 80°C and held for 5 minutes to liquefy the phenolic resin powder and bond the remaining powder. After the holding time is completed, the upper and lower plates of the flat vulcanizing machine are heated to 180°C, and a pressure of 20 MPa is applied to the mold. The pressure is maintained for 20 minutes, and then the pressure is released. At the same time, the heating of the upper and lower plates is stopped, and the mold is allowed to cool naturally to room temperature to cure the phenolic resin. The sample is then demolded to obtain a green blank.

[0107] Step 3: Carbonize the green blank obtained in Step 2 to obtain a C / C-Si green body;

[0108] Specifically, after evacuating to a vacuum level of 10 Pa, nitrogen gas is introduced into the furnace, and the temperature is raised to 900 °C at a rate of 1 °C / min. The temperature is held for 0.5 h, and nitrogen gas is continuously introduced during the heating and holding process to maintain the furnace pressure at 0-0.04 MPa. After the holding period, heating is stopped, and the furnace temperature is allowed to drop to 300 °C before nitrogen gas introduction is stopped. The furnace temperature is then allowed to cool to room temperature, and the sample is removed to obtain the C / C-Si billet.

[0109] Step 4: The C / C-Si preform obtained in Step 3 is subjected to silicon infiltration treatment with silicon powder to obtain the non-dense carbon ceramic friction material; the silicon powder has a particle size of 100 mesh and a silicon purity of ≥99wt.%.

[0110] Specifically, prepare silicon powder with a weight twice that of the C / C-Si billet obtained in step 3, spread the silicon powder at the bottom of a graphite crucible, and place the C / C-Si billet obtained in step 3 on top of the silicon powder; place the graphite crucible in a high-temperature furnace, evacuate the furnace, and raise the furnace temperature to 1550°C at a rate of 5°C / min, and hold for 2 hours; after the holding period, stop heating and wait for the furnace temperature to drop to room temperature, then take out the silicon-infiltrated billet material to obtain a non-dense carbon ceramic friction material.

[0111] The total process time for preparing the non-dense carbon ceramic friction material in this embodiment is 7 days.

[0112] The average density of the non-dense carbon ceramic friction material prepared in this embodiment is 2.1 g / cm³. 3 Porosity is 15 vol.%; maximum high temperature resistance is 1350℃; compressive strength is 82.9 MPa.

[0113] The silicon carbide volume content in the overall non-dense carbon ceramic friction material is 17%.

[0114] By replacing the metal mold shape in the preparation method of this embodiment with a mold in the shape of a friction plate, a friction plate made of the non-dense carbon ceramic friction material of this embodiment is prepared. In the AK-master program test, the wear of the friction plate is 63.9 μm; the coefficient of friction is stable between 0.6 and 0.7; at the same time, the wear of the carbon ceramic brake disc used in the test is 13 μm.

[0115] Example 3

[0116] This embodiment provides a non-dense carbon ceramic friction material, the preparation method of which includes the following steps:

[0117] Step 1: Weigh 25% of short-cut carbon fibers with a length range of 3-6mm, 5% of graphite powder, 30% of FeSi65, 7% of silicon carbide powder, 3% of boron nitride powder, and 30% of phenolic resin powder according to the weight ratio. Mix the above raw materials at room temperature using a dual-motion mixer for 50 minutes to obtain a mixed powder.

[0118] Wherein, the carbon content of the short-cut carbon fiber is ≥95wt.%;

[0119] The graphite powder has a particle size of 150 mesh and a carbon content of ≥96 wt.%.

[0120] The FeSi65 has a particle size of 150 mesh;

[0121] The silicon carbide powder has a particle size of 200 mesh;

[0122] The boron nitride powder has a particle size of 800 mesh;

[0123] The phenolic resin powder is a thermosetting phenolic resin powder with a particle size of 400 mesh.

[0124] Step 2: Heat, press, and solidify the mixed powder from Step 1 to obtain a raw blank;

[0125] Specifically, the mixed powder is filled into a cylindrical metal mold, which is then placed between the upper and lower plates of a flat vulcanizing machine. The upper and lower plates of the flat vulcanizing machine are heated to 80°C and held for 20 minutes to liquefy the phenolic resin powder and bond the remaining powder. After the holding time is completed, the upper and lower plates of the flat vulcanizing machine are heated to 180°C, and a pressure of 20 MPa is applied to the mold. The mold is held at this temperature and pressure for 30 minutes, and then the pressure is released. At the same time, the heating of the upper and lower plates is stopped, and the mold is allowed to cool naturally to room temperature to cure the phenolic resin. The sample is then demolded to obtain a green blank.

[0126] Step 3: Carbonize the green blank obtained in Step 2 to obtain a C / C-Si green body;

[0127] Specifically, after evacuating to a vacuum level of 10 Pa, nitrogen gas is introduced into the furnace, and the temperature is raised to 900 °C at a rate of 5 °C / min. The temperature is held for 1 hour, and nitrogen gas is continuously introduced during the heating and holding process to maintain the pressure inside the furnace at 0-0.04 MPa. After the holding period, heating is stopped, and the temperature inside the furnace is allowed to drop to 300 °C before nitrogen gas introduction is stopped. The furnace is then allowed to cool to room temperature, and the sample is removed to obtain the C / C-Si billet.

[0128] Step 4: The C / C-Si preform obtained in Step 3 is subjected to silicon infiltration treatment with silicon powder to obtain the non-dense carbon ceramic friction material; the silicon powder has a particle size of 150 mesh and a silicon purity of ≥99wt.%.

[0129] Specifically, prepare silicon powder with a weight twice that of the C / C-Si billet obtained in step 3, spread the silicon powder at the bottom of a graphite crucible, and place the C / C-Si billet obtained in step 3 on top of the silicon powder; place the graphite crucible in a high-temperature furnace, evacuate the furnace, and raise the furnace temperature to 1610℃ at a rate of 5℃ / min, and hold for 1 hour; after the holding period, stop heating and wait for the furnace temperature to drop to room temperature, and then take out the silicon-infiltrated billet material to obtain a non-dense carbon ceramic friction material.

[0130] The total process time for preparing the non-dense carbon ceramic friction material in this embodiment is 7 days.

[0131] The average density of the non-dense carbon ceramic friction material prepared in this embodiment is 1.8 g / cm³. 3 Porosity is 23 vol.%; maximum high temperature resistance is 1350℃; compressive strength is 79.6 MPa.

[0132] The silicon carbide volume content in the overall non-dense carbon ceramic friction material is 21%.

[0133] By replacing the metal mold shape in the preparation method of this embodiment with a mold in the shape of a friction plate, a friction plate made of the non-dense carbon ceramic friction material of this embodiment is prepared. In the AK-master program test, the wear of the friction plate is 95.0 μm; the coefficient of friction is stable between 0.6 and 0.7; at the same time, the wear of the carbon ceramic brake disc used in the test is 8 μm.

[0134] Example 4

[0135] This embodiment provides a non-dense carbon ceramic friction material, the preparation method of which includes the following steps:

[0136] Step 1: Weigh 15% of short-cut carbon fibers with a length range of 3-6mm, 5% of graphite powder, 50% of FeSi90, 5% of silicon carbide powder, 5% of boron nitride powder, and 20% of phenolic resin powder according to the weight ratio. Mix the above raw materials at room temperature using a dual-motion mixer for 60 minutes to obtain a mixed powder.

[0137] Wherein, the carbon content of the short-cut carbon fiber is ≥95wt.%;

[0138] The graphite powder has a particle size of 150 mesh and a carbon content of ≥96 wt.%.

[0139] The FeSi90 has a particle size of 200 mesh;

[0140] The silicon carbide powder has a particle size of 300 mesh;

[0141] The boron nitride powder has a particle size of 1000 mesh;

[0142] The phenolic resin powder is a thermosetting phenolic resin powder with a particle size of 600 mesh.

[0143] Step 2: Heat, press, and solidify the mixed powder from Step 1 to obtain a raw blank;

[0144] Specifically, the mixed powder is filled into a cylindrical metal mold, which is then placed between the upper and lower plates of a flat vulcanizing machine. The upper and lower plates of the flat vulcanizing machine are heated to 80°C and held for 30 minutes to liquefy the phenolic resin powder and bond the remaining powder. After the holding time is completed, the upper and lower plates of the flat vulcanizing machine are heated to 180°C, and a pressure of 20 MPa is applied to the mold. The pressure is maintained for 20 minutes, and then the pressure is released. At the same time, the heating of the upper and lower plates is stopped, and the mold is allowed to cool naturally to room temperature to cure the phenolic resin. The sample is then demolded to obtain a green blank.

[0145] Step 3: Carbonize the green blank obtained in Step 2 to obtain a C / C-Si green body;

[0146] Specifically, after evacuating to a vacuum level of 10 Pa, nitrogen gas is introduced into the furnace, and the temperature is raised to 900 °C at a rate of 4 °C / min. The temperature is held for 2.5 h, and nitrogen gas is continuously introduced during the heating and holding process to maintain the furnace pressure at 0-0.04 MPa. After the holding period, heating is stopped, and the furnace temperature is allowed to drop to 300 °C before nitrogen gas introduction is stopped. The furnace temperature is then allowed to cool to room temperature, and the sample is removed to obtain the C / C-Si billet.

[0147] Step 4: The C / C-Si preform obtained in Step 3 is subjected to silicon infiltration treatment with silicon powder to obtain the non-dense carbon ceramic friction material; the silicon powder has a particle size of 100 mesh and a silicon purity of ≥99wt.%.

[0148] Specifically, prepare silicon powder with a weight twice that of the C / C-Si billet obtained in step 3, spread the silicon powder at the bottom of a graphite crucible, and place the C / C-Si billet obtained in step 3 on top of the silicon powder; place the graphite crucible in a high-temperature furnace, evacuate the furnace, and raise the furnace temperature to 1650℃ at a rate of 5℃ / min, and hold for 1.5h; after the holding period, stop heating and wait for the furnace temperature to drop to room temperature, then take out the silicon-infiltrated billet material to obtain a non-dense carbon ceramic friction material.

[0149] The total process time for preparing the non-dense carbon ceramic friction material in this embodiment is 7 days.

[0150] The average density of the non-dense carbon ceramic friction material prepared in this embodiment is 2.2 g / cm³. 3 Porosity is 15 vol.%; maximum high temperature resistance is 1350℃; compressive strength is 78.1 MPa.

[0151] The silicon carbide volume content in the overall non-dense carbon ceramic friction material is 28%.

[0152] By replacing the metal mold shape in the preparation method of this embodiment with a mold in the shape of a friction plate, a friction plate made of the non-dense carbon ceramic friction material of this embodiment is prepared. In the AK-master program test, the wear of the friction plate is 80.3 μm; the coefficient of friction is stable between 0.6 and 0.7; at the same time, the wear of the carbon ceramic brake disc used in the test is 11 μm.

[0153] Example 5

[0154] This embodiment provides a non-dense carbon ceramic friction material, the preparation method of which includes the following steps:

[0155] Step 1: Weigh out 35% of short-cut carbon fibers with a length range of 3-6 mm, 5% of graphite powder, 10% of FeSi75, 20% of FeSi90, 10% of silicon carbide powder, 5% of boron nitride powder, and 15% of phenolic resin powder according to the weight ratio. Mix the above raw materials at room temperature using a dual-motion mixer for 20 minutes to obtain a mixed powder.

[0156] Wherein, the carbon content of the short-cut carbon fiber is ≥95wt.%;

[0157] The graphite powder has a particle size of 150 mesh and a carbon content of ≥96 wt.%.

[0158] The FeSi75 has a particle size of 300 mesh;

[0159] The FeSi90 has a particle size of 300 mesh;

[0160] The silicon carbide powder has a particle size of 200 mesh;

[0161] The boron nitride powder has a particle size of 800 mesh;

[0162] The phenolic resin powder is a thermosetting phenolic resin powder with a particle size of 500 mesh.

[0163] Step 2: Heat, press, and solidify the mixed powder from Step 1 to obtain a raw blank;

[0164] Specifically, the mixed powder is filled into a cylindrical metal mold, which is then placed between the upper and lower plates of a flat vulcanizing machine. The upper and lower plates of the flat vulcanizing machine are heated to 80°C and held for 25 minutes to liquefy the phenolic resin powder and bond the remaining powder. After the holding time is completed, the upper and lower plates of the flat vulcanizing machine are heated to 180°C, and a pressure of 20 MPa is applied to the mold. The mold is held at this temperature and pressure for 30 minutes, and then the pressure is released. At the same time, the heating of the upper and lower plates is stopped, and the mold is allowed to cool naturally to room temperature to cure the phenolic resin. The sample is then demolded to obtain a green blank.

[0165] Step 3: Carbonize the green blank obtained in Step 2 to obtain a C / C-Si green body;

[0166] Specifically, after evacuating to a vacuum level of 10 Pa, nitrogen gas is introduced into the furnace, and the temperature is raised to 900°C at a rate of 2°C / min. The temperature is held for 3 hours, and nitrogen gas is continuously introduced during the heating and holding process to maintain the furnace pressure at 0-0.04 MPa. After the holding period, heating is stopped, and the furnace temperature is allowed to drop to 300°C before nitrogen gas introduction is stopped. The furnace temperature is then allowed to cool to room temperature, and the sample is removed to obtain the C / C-Si billet.

[0167] Step 4: The C / C-Si preform obtained in Step 3 is subjected to silicon infiltration treatment with silicon powder to obtain the non-dense carbon ceramic friction material; the silicon powder has a particle size of 150 mesh and a silicon purity of ≥99wt.%.

[0168] Specifically, prepare silicon powder with a weight twice that of the C / C-Si billet obtained in step 3, spread the silicon powder at the bottom of a graphite crucible, and place the C / C-Si billet obtained in step 3 on top of the silicon powder; place the graphite crucible in a high-temperature furnace, evacuate the furnace, and raise the furnace temperature to 1590°C at a rate of 5°C / min, and hold for 2 hours; after the holding period, stop heating and wait for the furnace temperature to drop to room temperature, then take out the silicon-infiltrated billet material to obtain a non-dense carbon ceramic friction material.

[0169] The total process time for preparing the non-dense carbon ceramic friction material in this embodiment is 7 days.

[0170] The average density of the non-dense carbon ceramic friction material prepared in this embodiment is 1.9 g / cm³. 3 Porosity is 25 vol.%; maximum high temperature resistance is 1350℃; compressive strength is 80.5 MPa.

[0171] The silicon carbide volume content in the overall non-dense carbon ceramic friction material is 25%.

[0172] By replacing the metal mold shape in the preparation method of this embodiment with a mold in the shape of a friction plate, a friction plate made of the non-dense carbon ceramic friction material of this embodiment is prepared. In the AK-master program test, the wear of the friction plate is 89.4 μm; the coefficient of friction is stable between 0.6 and 0.7; at the same time, the wear of the carbon ceramic brake disc used in the test is 8 μm.

[0173] Comparative Example 1

[0174] This comparative example is based on the metal-based powder metallurgy material prepared according to the literature: Zhao SQ, Yan QZ, Peng T, et al. The braking behavior of Cu-based powder metallurgy brake pads mated with C / C-SiC disk for high-speed train. Wear, 2020, 448-449: 203237.

[0175] The average density of the metal-based powder metallurgy material prepared in this comparative example is 6.1 g / cm³. 3 It has a density approximately three times that of the non-dense carbon ceramic friction material of this invention; a porosity of 15.7 vol.%; a high-temperature resistance limit of 800℃; and a compressive strength of 104.3 MPa.

[0176] In this comparative example, the friction pad prepared from the metal-based powder metallurgy material was subjected to braking tests using the AK-master testing program, with the testing method being the same as in Example 1. The resulting thermal fade braking curve is shown in Figure 3. It can be seen that with the increase in braking temperature and the number of friction cycles, the instantaneous change curve of the friction coefficient of the friction pad prepared from the metal-based powder metallurgy material in this comparative example fluctuates relatively greatly, and the average friction coefficient shows a decreasing trend. It can also be seen that the braking pressure gradually increases. In other words, the performance of the friction pad prepared from the metal-based powder metallurgy material in this comparative example is not as stable as that of the friction pad prepared from the non-dense carbon-ceramic friction material of this invention in 15 consecutive uninterrupted braking tests. Using the metal-based powder metallurgy material of this comparative example, the wear amount of the friction pad in the AK-master test was 185.7 μm; the friction coefficient was 0.5-0.7; while the wear amount of the carbon-ceramic brake disc used in the test was 120.5 μm.

[0177] The reason for the unstable performance of the aforementioned metal-based powder metallurgy friction materials is that during the braking process, instantaneous hot spots (temperatures exceeding 1000℃) are generated in localized areas of the friction pads prepared in the comparative model. The Cu matrix in these localized areas softens or melts, adhering to the surface of the carbon-ceramic brake disc, generating uneven viscous resistance, thus leading to unstable friction performance. Simultaneously, the high wear is mainly due to the fact that the powder metallurgy friction material is primarily composed of a metal matrix, whose hardness is much lower than that of the ceramic phase of the carbon-ceramic brake disc. During braking, it is more easily cut by the hard ceramic phase of the brake disc's friction surface, resulting in wear.

[0178] Comparative Example 2

[0179] This comparative example provides a prior art resin-based friction material and its preparation method, the specific steps of which are as follows:

[0180] 30 parts by weight of boron-modified phenolic resin powder, 5 parts by weight of steel fiber, 10 parts by weight of carbon fiber, 1 part by weight of aluminum titanate, 1 part by weight of Al2O3, 8 parts by weight of SiO2, 2 parts by weight of MgO, 1 part by weight of BaSO4, 10 parts by weight of graphite, 3 parts by weight of MoS2, 5 parts by weight of SiC, 0.8 parts by weight of antimony oxide, and 1 part by weight of barite were mixed evenly. The mixed powder was placed in a mold, the mold was heated to 180°C, and a pressure of 40 MPa was applied using a flat vulcanizing machine. After holding the temperature and pressure for 20 minutes, the material was demolded. Then, the material was placed in an electric heating blast drying oven for heat treatment at 200°C for 12 hours to obtain the resin-based friction material in this comparative example.

[0181] The average density of the resin-based friction material prepared in this comparative example is 3.3 g / cm³. 3Porosity is 6.7 vol.%; maximum high temperature resistance is 400℃; compressive strength is 79.6 MPa.

[0182] In this comparative example, the friction pads prepared from the resin-based friction material were subjected to braking tests using the AK-master testing program, with the testing method being the same as in Example 1. The resulting thermal fade braking curves are shown in Figure 4. It can be seen that with the increase in braking temperature and the number of friction cycles, the instantaneous change curve of the friction coefficient of the friction pads prepared from the resin-based material in this comparative example shows a significant decreasing trend, and the average friction coefficient also shows a decreasing trend. It can also be seen that the braking pressure gradually increases and becomes unstable, exhibiting a significant thermal fade problem. In other words, the performance of the friction pads prepared from the resin-based friction material in this comparative example is not as stable as that of the friction pads prepared from the non-dense carbon-ceramic friction material of this invention in 15 consecutive uninterrupted braking tests. Using the resin-based friction material of this comparative example, the wear of the friction pads in the AK-master test was 534.4 μm; the friction coefficient was 0.3-0.5; while the wear of the carbon-ceramic brake disc used in the test was 470.1 μm.

[0183] The reason why the performance of the above-mentioned resin-based friction materials is not stable is that the resin-based friction materials rely on the resin to bind together more than a dozen other fillers. The resin decomposes at temperatures above 400°C and cannot effectively bind the other fillers. Therefore, the coefficient of friction is prone to fluctuate with the changes in the composition of the friction surface. Without the binding of the resin, the other components are more likely to be worn away, resulting in a large amount of wear.

[0184] Comparative Example 3

[0185] This comparative example is based on the literature: Shangwu Fan, Litong Zhang, Yongdong Xu, et al. Microstructure and properties of 3D needle-punched carbon / silicon carbide brake materials. Composites Science and Technology. 2007, 67: 2390-2398. The high-density carbon ceramic material prepared by chemical vapor deposition has a total process cycle of three months, which is much longer than the process cycle of preparing the non-density carbon ceramic friction material of this invention, resulting in high time costs.

[0186] The average density of the high-density carbon ceramic material prepared in this comparative example is 2.1 g / cm³. 3 Porosity is 6.3 vol.%; extreme high temperature is 1350℃; compressive strength is 212 MPa.

[0187] In this comparative example, the friction pad prepared from the high-density, low-porosity carbon-ceramic material was subjected to braking tests using the AK-master testing program, with the testing method being the same as in Example 1. The resulting thermal fade braking curve is shown in Figure 5. It can be seen that with the increase in braking temperature and the number of friction cycles, the instantaneous change curve of the friction coefficient of the friction pad prepared from the high-density, low-porosity carbon-ceramic material in this comparative example exhibits large fluctuations and instability, and the average friction coefficient shows a trend of decreasing with vibration. It can also be seen that the braking pressure gradually increases and becomes unstable. In other words, the performance of the friction pad prepared from the high-density, low-porosity carbon-ceramic material in this comparative example is not as stable as that of the friction pad prepared from the non-density carbon-ceramic friction material of this invention in 15 consecutive uninterrupted braking tests. Using the high-density carbon-ceramic material of this comparative example, the wear of the friction pad in the AK-master test was 412 μm; the friction coefficient was 0.6-0.9, while the wear of the carbon-ceramic brake disc used in the test was 98 μm.

[0188] The reason for the unstable performance of the aforementioned carbon-ceramic friction material is that when carbon-ceramic brake discs and friction pads of the same material are rubbed together, since the material composition is C, Si, and SiC, all three phases are brittle phases, they will brittlely peel off when the discs and pads are rubbed together. The peeled Si and SiC are relatively hard and remain between the friction surfaces, acting as hard abrasives, producing a "three-body" abrasive wear effect. The mechanical meshing and shearing of hard micro-protrusions and abrasives leads to unstable friction performance, and the severe abrasive wear effect results in high wear.

[0189] Comparative Example 4

[0190] This comparative example provides a carbon-ceramic friction material, using petroleum coke instead of graphite powder in Example 1, and its preparation method is the same as in Example 1:

[0191] The average density of the carbon-ceramic friction material prepared in this comparative example is 2.0 g / cm³. 3 The porosity is 25.6 vol.%; the maximum temperature resistance is 900℃; and the compressive strength is 62.5 MPa.

[0192] In this comparative example, the friction pads prepared from the carbon-ceramic friction material were subjected to braking tests using the AK-master testing program, with the testing method being the same as in Example 1. The resulting thermal fade braking curves are shown in Figure 6. It can be seen that with the increase in braking temperature and the number of friction cycles, the instantaneous change curve of the friction coefficient in this comparative example fluctuates significantly and is unstable. The average friction coefficient shows a trend of first increasing and then decreasing, indicating that the braking pressure is also unstable. In other words, the performance of the friction pads prepared from the carbon-ceramic friction material in this comparative example is not as stable as that of the friction pads prepared from the non-dense carbon-ceramic friction material of this invention in 15 consecutive uninterrupted braking tests. Using the carbon-ceramic friction material of this comparative example, the wear of the friction pads in the AK-master test was 228.9 μm; the friction coefficient was 0.6-0.8; and the wear of the carbon-ceramic brake disc used in the test was 159.7 μm.

[0193] The reason why the performance of the aforementioned carbon ceramic friction materials is not stable is mostly due to the complex composition of petroleum coke, which is mostly granular and affects the friction performance. The graphite powder selected in this invention has a layered structure and has excellent lubrication performance. Adding graphite powder is beneficial to play a lubricating effect during braking, reducing abrasive wear caused by hard particles, thereby stabilizing the friction coefficient and reducing the amount of material wear.

[0194] It should be understood that the present invention is not limited to what has been described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A non-dense carbon ceramic friction material, characterized in that, The non-dense carbon ceramic friction material is obtained by silicon infiltration treatment of C / C-Si preform with silicon powder. The raw materials for preparing the C / C-Si preform include short-cut carbon fibers, graphite powder, silicon-iron mixture, silicon carbide powder, boron nitride powder, and phenolic resin powder. The non-dense carbon ceramic friction material has a porosity of 15-25 vol.%; a high temperature limit of 1350℃; and a compressive strength of 80.5 ± 2.4 MPa.

2. The non-dense carbon ceramic friction material according to claim 1, characterized in that, The components and proportions of the raw materials for preparing the C / C-Si preform are as follows, by weight: Short-cut carbon fiber: 15-35%; Graphite powder: 5-10%; Ferrosilicon mixture: 30-50%; Silicon carbide powder: 5-10%; Boron nitride powder: 3-8%; Phenolic resin powder: 15-30%.

3. The non-dense carbon ceramic friction material according to claim 1, characterized in that, The mass ratio of the C / C-Si preform to the silicon powder is 1:

2.

4. A method for preparing the non-dense carbon ceramic friction material according to any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Weigh and mix short-cut carbon fibers, graphite powder, ferrosilicon alloy powder, silicon carbide powder, boron nitride powder, and phenolic resin powder to obtain a mixed powder. Step 2: Heat, press, and solidify the mixed powder from Step 1 to obtain a raw blank; Step 3: Carbonize the green blank obtained in Step 2 to obtain a C / C-Si green body; Step 4: The C / C-Si preform obtained in Step 3 is subjected to melt silicon infiltration treatment with silicon powder to obtain the non-dense carbon ceramic friction material.

5. A friction plate, characterized in that, The friction pad is made of the non-dense carbon ceramic friction material according to any one of claims 1-3; The wear of the friction pads in the AK-master program test was 52.8-95.0 μm; The coefficient of friction is 0.6-0.

7.

6. A braking device, characterized in that, The braking device includes the friction pad as described in claim 5.

7. The braking device according to claim 6, characterized in that, The braking device also includes a brake disc.

8. A car, characterized in that, The vehicle includes the braking device according to any one of claims 6-7.

9. An aircraft, characterized in that, The aircraft includes the braking device as described in any one of claims 6-7.

10. A high-speed railway, characterized in that, The high-speed rail includes the braking device described in any one of claims 6-7.

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