Aluminum silicon carbide brake disc and method of making same

Abstract

The application discloses an aluminum silicon carbide brake disc and a preparation method thereof. The aluminum silicon carbide brake disc comprises a disc body and a joint head coaxially connected with the disc body. The disc body is a multilayer structure with a total thickness of 28-32 mm, comprising an upper surface layer, a middle layer and a lower surface layer. The upper surface layer and the lower surface layer are both aluminum silicon carbide materials with a SiC volume fraction of 70-75%, and the thicknesses are 2-4 mm respectively. The middle layer and the joint head are both aluminum silicon carbide materials with a SiC volume fraction of 45-58%. The density of the aluminum silicon carbide brake disc provided by the application is only 40% of the density of cast iron used for cast iron brake discs, which meets the lightweight requirement. The thermal conductivity reaches 190 W / m.k, which reduces the high-temperature decay and thermal cracking of the friction performance in the braking process, and the aluminum silicon carbide brake disc has more excellent high-temperature friction performance, more excellent impact toughness and higher reliability than traditional brake discs.

Description

Technical Field

[0001] This invention relates to the field of brake disc technology, and in particular to an aluminum silicon carbide brake disc and its preparation method. Background Technology

[0002] Currently, cast iron brake discs are a commonly used material with mature technology and low price. However, they suffer from severe high-temperature thermal degradation, are heavy, have poor thermal conductivity, and are prone to thermal cracking. They cannot adequately meet the needs of the ever-developing automotive industry, especially the lightweighting requirements of new energy vehicles.

[0003] Carbon-carbon composites, which use carbon fiber to reinforce the carbon matrix, experience a significant decrease in friction coefficient under humid / low-temperature environments. The complexity of the carbon-carbon composite manufacturing process results in a large proportion of manufacturing costs, including labor and equipment depreciation. The production equipment also faces high technological barriers, long densification cycles, and substantial power consumption. Due to cost constraints, carbon-carbon composites cannot yet be widely used in the automotive industry.

[0004] Carbon-ceramic composites utilize carbon fiber reinforced silicon carbide, combining the high mechanical strength of carbon fiber with the wear resistance and oxidation resistance of ceramic materials. They possess characteristics such as high temperature resistance, low density, high coefficient of friction, minimal thermal fading, stable performance, high safety, and long lifespan, effectively shortening braking distance while overcoming the problem of low coefficient of friction in wet / low-temperature environments. However, like carbon-carbon composites, carbon-ceramic composites suffer from long densification cycles and high energy consumption, and the expensive precursors such as polycarbosilanes result in high material costs, severely limiting their application in the automotive industry.

[0005] Therefore, there is a need for a new type of brake disc with acceptable cost to compensate for the defects of existing cast iron brake discs, such as large weight, severe high-temperature heat fade, and susceptibility to thermal cracking. Summary of the Invention

[0006] This invention provides an aluminum silicon carbide brake disc and its preparation method to solve the technical problems of existing cast iron brake discs, such as large weight, severe high-temperature thermal degradation, and susceptibility to thermal cracking.

[0007] According to one aspect of the present invention, an aluminum silicon carbide brake disc is provided, comprising a disc body and a coupling coaxially connected to the disc body. The disc body is a multi-layer structure with a total thickness between 28 and 32 mm, comprising an upper surface layer, a middle layer, and a lower surface layer. The upper surface layer and the lower surface layer are both aluminum silicon carbide materials with a SiC volume fraction of 70-75% and a thickness of 2-4 mm, respectively. The middle layer and the coupling are both aluminum silicon carbide materials with a SiC volume fraction of 45-58%.

[0008] Furthermore, the aluminum element in the aluminum silicon carbide brake disc exists in the form of a continuously distributed aluminum alloy.

[0009] Furthermore, the aluminum-silicon carbide brake disc has a coefficient of friction ≥0.28 at 480℃; and an impact toughness ≥26KJ / m. 2 .

[0010] According to another aspect of the present invention, a method for preparing the above-mentioned aluminum silicon carbide brake disc is also provided, comprising the following steps:

[0011] The mixture of SiC powder and binder is dried, pressed and cured to obtain a SiC preform with a porosity of 25-30%.

[0012] SiC powder is filled into the mold, and the porosity of SiC after filling is 42-55%; a SiC preform matching the shape and size of the bottom layer of the mold is placed in it; SiC powder is filled into the middle layer of the mold, and the porosity of SiC after filling is 42-55%; another SiC preform matching the shape and size of the upper layer of the mold is placed in it.

[0013] An aluminum alloy is impregnated, and after demolding, an aluminum silicon carbide brake disc is obtained, wherein the aluminum alloy in the aluminum silicon carbide brake disc is a continuously distributed phase.

[0014] Furthermore, the mixture of SiC powder and binder is made by mixing SiC powder with particle sizes of 100μm, 50μm, 28μm and 5μm with binder.

[0015] Further, the curing includes: holding the pressed preform at 500-650°C for 45-75 minutes.

[0016] Furthermore, filling the intermediate layer of the head mold or disc mold with SiC powder includes: filling the intermediate layer of the head mold or disc mold with SiC powder of 40-55μm particle size by adding and vibrating simultaneously, wherein the vibration frequency is 50-60Hz and the amplitude is 2-4mm.

[0017] Furthermore, the impregnated aluminum alloy includes: aluminum alloy impregnated under pressure in an inert gas atmosphere.

[0018] Furthermore, the aluminum alloy added during the pressure impregnation process is molten aluminum alloy, the impregnation pressure is 4-6 MPa, and the holding time is 30-60 min.

[0019] Furthermore, before pressure impregnation, the SiC in the head mold and the disc mold is preheated to 580-650°C.

[0020] The present invention has the following beneficial effects:

[0021] Based on the theoretical densities of aluminum and silicon carbide and their ratio, the average density of the aluminum-silicon carbide brake disc provided by this invention is calculated to be 2.9 g / mm². 3 The density of cast iron used for cast iron brake discs is approximately 7.35 g / mm³. 3 40% of that is more in line with the requirements of the lightweighting target for new energy vehicles.

[0022] The aluminum silicon carbide brake disc provided by this invention has a thermal conductivity of 190 W / m·K, which is much greater than the thermal conductivity of 50 W / m·K of cast iron brake discs. This facilitates heat dissipation during braking and reduces high-temperature degradation and thermal cracking of frictional performance during braking.

[0023] The upper and lower surfaces of the aluminum-silicon carbide brake disc body provided by this invention are made of aluminum-silicon carbide material with a SiC volume fraction of 70-75%. The increased silicon carbide volume fraction significantly improves the high-temperature friction performance of the material, resulting in a friction coefficient ≥0.28 at 480℃ (while aluminum-silicon carbide material with a SiC volume fraction of 42-58% has a friction coefficient of only 0.2 at 480℃). The middle layer and the joint portion of the aluminum-silicon carbide brake disc body provided by this invention are also made of aluminum-silicon carbide material with a SiC volume fraction of 42-58%. The lower silicon carbide volume fraction gives the aluminum-silicon carbide brake disc better impact toughness ≥26KJ / m. 2 (While aluminum silicon carbide materials with a SiC volume fraction of 70-75% have an impact toughness of 13 KJ / m) 2 Therefore, the multi-layer aluminum silicon carbide brake disc provided by this invention has superior high-temperature friction performance and superior impact toughness compared to traditional brake discs, resulting in higher reliability of the brake disc.

[0024] The method for preparing aluminum silicon carbide brake discs provided by this invention has controllable costs. Specifically, the raw materials (silicon carbide powder and aluminum alloy) for aluminum silicon carbide brake discs are inexpensive, the production process is simple, and the production efficiency is high, which has good application prospects in the automotive industry.

[0025] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0026] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0027] Figure 1 This is a schematic diagram of the brake disc according to a preferred embodiment of the present invention.

[0028] Legend:

[0029] 1-Head; 2-Disc body; 21-Upper surface layer; 22-Middle layer; 23-Lower surface layer. Detailed Implementation

[0030] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0031] like Figure 1 As shown, an embodiment of the first aspect of this application provides an aluminum silicon carbide brake disc, including a disc body 2 and a connector 1 coaxially connected to the disc body 2. The disc body 2 is a multi-layer structure with a total thickness between 28 and 32 mm, including an upper surface layer 21, a middle layer 22 and a lower surface layer 23. The upper surface layer 21 and the lower surface layer 23 are both aluminum silicon carbide materials with a SiC volume fraction of 70-75% and a thickness of 2-4 mm, respectively. The middle layer 22 and the connector 1 are both aluminum silicon carbide materials with a SiC volume fraction of 45-58%.

[0032] In the embodiments of this application, the total thickness of the disk body 2 is 28-32mm (which can be any value or combination of 28mm, 29mm, 30mm, 31mm, 32mm, etc.). The thicknesses of the upper surface layer 21 and the lower surface layer 23 are 2-4mm (which can be any value or combination of 2mm, 3mm, 4mm, etc.). Then the thickness of the intermediate layer 22 is the total thickness of the disk body 2 minus the thicknesses of the upper surface layer 21 and the lower surface layer 23, that is, the thickness of the intermediate layer 22 is 20-28mm (which can be any value or combination of 20mm, 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, 27mm, 28mm, etc.).

[0033] According to the embodiments of this application, the thickness of the upper surface layer 21 and the lower surface layer 23 is 2-4 mm respectively. Typically, the wear life of a brake disc is 2 mm. Therefore, in order to meet the wear life requirement, the upper and lower surface layers are selected to be at least 2 mm. If the surface layer is too thick, it means that the intermediate layer has to be thinned if the overall size of the disc remains unchanged. Since the intermediate layer has high impact toughness, thinning the intermediate layer will reduce the overall impact toughness of the brake disc.

[0034] In the embodiments of this application, both the upper surface layer 21 and the lower surface layer 23 are aluminum silicon carbide materials with a SiC volume fraction of 70-75%. For example, their SiC volume fraction can be any value or combination of 70%, 71%, 72%, 73%, 74%, 75%, etc.

[0035] In the embodiments of this application, the intermediate layer 22 and the connector 1 are both aluminum silicon carbide materials with a SiC volume fraction of 45% to 58%. For example, their SiC volume fraction can be any value or combination range of 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, etc.

[0036] According to an embodiment of this application, the density of the aluminum silicon carbide brake disc is 2.9 g / mm². 3 The density is approximately 40% of that of cast iron used in cast iron brake discs (7.35 g / mm³), which better meets the lightweight requirements of new energy vehicles. The multi-layer aluminum-silicon carbide brake disc has a thermal conductivity of 190 W / m·K, far exceeding the 50 W / m·K of cast iron brake discs. This facilitates heat dissipation during braking, reducing high-temperature degradation and thermal cracking of frictional performance.

[0037] The upper surface layer 21 and lower surface layer 23 of the aluminum-silicon carbide brake disc body 2 provided in this embodiment are aluminum-silicon carbide materials with a SiC volume fraction of 70-75%. The increased silicon carbide volume fraction significantly improves the high-temperature friction performance of the material, resulting in a friction coefficient ≥0.28 for the brake disc at 480℃. The intermediate layer 22 and the coupling 1 of the aluminum-silicon carbide brake disc body 2 provided in this embodiment are aluminum-silicon carbide materials with a SiC volume fraction of 42-58%. The lower silicon carbide volume fraction gives the aluminum-silicon carbide brake disc better impact toughness ≥26KJ / m. 2 Therefore, the multi-layer aluminum silicon carbide brake disc provided in this application embodiment has superior high-temperature friction performance and superior impact toughness compared to traditional brake discs, resulting in higher reliability of the brake disc.

[0038] In the embodiments of this application, the aluminum element in the aluminum silicon carbide brake disc exists in the form of a continuously distributed aluminum alloy. Throughout the entire brake disc, the aluminum element in the clutch 1 and the disc body 2 (including the upper surface layer 21, the middle layer 22, and the lower surface layer 23) exists in the form of a continuously distributed aluminum alloy. This continuously distributed aluminum alloy fuses the clutch 1 and the disc body 2 into one unit, and the tensile strength at the joint is greater than 160 MPa, meeting application requirements.

[0039] In the embodiments of this application, such as Figure 1 As shown, the connector 1 part has multiple mounting holes for easy installation.

[0040] Another embodiment of this application provides a method for preparing the above-mentioned aluminum silicon carbide brake disc, comprising the following steps:

[0041] The mixture of SiC powder and binder is dried, pressed and cured to obtain a SiC preform with a porosity of 25-30%.

[0042] SiC powder is filled into the mold, and the porosity of SiC after filling is 42-55%; a SiC preform matching the shape and size of the bottom layer of the mold is placed in it; SiC powder is filled into the middle layer of the mold, and the porosity of SiC after filling is 42-55%; another SiC preform matching the shape and size of the upper layer of the mold is placed in it.

[0043] An aluminum alloy is impregnated, and after demolding, an aluminum silicon carbide brake disc is obtained, wherein the aluminum alloy in the aluminum silicon carbide brake disc is a continuously distributed phase.

[0044] According to an embodiment of this application, the porosity of the SiC preform is 25-30%. The aforementioned reserved voids provide space for subsequent aluminum alloy impregnation. The reserved porosity is the proportion of the aluminum alloy after impregnation of the upper surface layer 21 and the lower surface layer 23 (the aluminum alloy completely fills the voids after impregnation). SiC powder is then filled into the head mold and the intermediate layer of the disc mold, satisfying a SiC porosity of 42-55% after filling. The aforementioned reserved porosity also provides space for subsequent aluminum alloy impregnation. The reserved porosity is the proportion of the aluminum alloy after impregnation of the head or intermediate layer 22 (the aluminum alloy completely fills the voids after impregnation).

[0045] In the process of impregnating aluminum alloy, the bottom and top layers of the disc mold are filled with SiC preforms with a preset porosity, and the middle layer of the head mold and the disc mold is filled with SiC powder with a preset porosity. After one impregnation, the aluminum alloy is distributed in a continuous phase in the aluminum silicon carbide brake disc.

[0046] In the embodiments of this application, the mixture of SiC powder and binder is prepared by mixing a mixture of SiC powder with particle sizes of 100μm, 50μm, 28μm, and 5μm with a binder. By using different particle size ratios (gradations), the density of the preform can be increased under sufficient pressure, i.e., the volume fraction of silicon carbide in the final composite material can be increased. This is because, for particles of a single size, due to the gaps between particles, it is difficult to achieve a volume fraction of more than 70% even under high pressure. For example, if the density of the preform obtained by pressing the above powder under a certain pressure is 2.2 g / mm³, 3 The theoretical density of silicon carbide is 3.17 g / mm³. 3 Therefore, the porosity of the preform can be calculated as 1-2.2 / 3.17=30.6%, meaning that after impregnation, the aluminum alloy fills the pores, and the volume fraction of the aluminum alloy is 30.6%, while the volume fraction of silicon carbide in the composite material is 69.4%.

[0047] In some embodiments, the method for preparing the above-mentioned aluminum silicon carbide brake disc includes:

[0048] SiC powders with particle sizes of 100μm, 50μm, 28μm, and 5μm were mixed uniformly in a ratio of 7:1:1:1. 2-5% (by weight) of a water-based binder (aluminum dihydrogen phosphate) was added, and the mixture was stirred in a kneader to obtain a mixture. The mixture was dried at 100℃ for 1 hour to obtain a powder. The powder was then granulated and sieved through a 40-mesh sieve, and a preform blank was obtained under a pressure of 200-300 MPa. The preform blank was then cured at 500-650℃ for 45-75 minutes (e.g., 1 hour) to obtain a silicon carbide preform with a density of 2.219-2.377 g / mm². 3 In this process, the precast blank can be set to match the shape and size of the mold to be used later.

[0049] First, add silicon carbide powder with a particle size (D50) of 40-55μm to the die, with a mass of... (V 合头 It refers to the volume of the mating part in the mold. (3.17 is the volume fraction of silicon carbide at this location, and 3.17 is the theoretical density of silicon carbide). Silicon carbide powder with a particle size (D50) of 40-55μm is spread evenly in the inner cavity of the mold head by vibration. The vibration frequency is 50-60Hz, the amplitude is 2-4mm, and the vibration time is 4-6min.

[0050] Then place one of the preforms at the bottom of the brake disc mold, with the shape and size of the preform matching the bottom layer of the brake disc mold.

[0051] Then, silicon carbide powder with a particle size (D50) of 40-55 μm is added to the intermediate layer mold, with a mass of... (V 中间层 It refers to the volume of the middle layer of the mold. (3.17 is the volume fraction of silicon carbide at this location, and 3.17 is the theoretical density of silicon carbide). Silicon carbide powder with a particle size (D50) of 40-55μm is spread evenly in the inner cavity of the middle layer of the mold by vibration. The vibration frequency is 50-60Hz, the amplitude is 2-4mm, and the vibration time is 4-6min.

[0052] Next, place another silicon carbide preform from step 1 on top of the powder. The shape and size of the preform match the upper layer of the brake disc mold.

[0053] Finally, the integral mold containing the silicon carbide preform and powder is preheated to 580-650℃, then placed in a pressure infiltration furnace. Molten aluminum alloy is added (temperature 680-780℃), the furnace door is tightly closed, and a vacuum is drawn to 500-5000Pa. N2 is added until the furnace pressure reaches 4-6MPa, and the pressure is maintained for 30-60 minutes to complete the aluminum alloy infiltration process. The workpiece is then removed, and the mold is disassembled to obtain a multilayer aluminum silicon carbide brake disc blank.

[0054] According to an embodiment of this application, the inner cavity of the mold is determined based on the size of the brake disc, meaning the total volume of the mold's inner cavity is fixed. Then, by calculating the addition of a certain mass of silicon carbide powder, the required volume fraction can be obtained. For example, assuming the inner cavity volume is 100 mm²... 3 The mass of silicon carbide powder added is 160g, and the theoretical density of silicon carbide powder is 3.17g / mm². 3 The theoretical volume of silicon carbide powder inside the cavity can be calculated to be 160 / 3.17 = 50.5 mm. 3 Therefore, the volume fraction of silicon carbide in the composite material after impregnation is 50.5 / 100*100% = 50.5%. After the above steps, the surface layer of the mold before impregnation has a high density (i.e., small gaps between silicon carbide particles), while the density of the middle layer 22 and the joint part is low (i.e., large gaps between silicon carbide particles). Then, through the impregnation process, the aluminum alloy fills their pores. The aluminum in the two volume fraction aluminum silicon carbide materials is the same continuous aluminum alloy, fusing the two volume fraction aluminum silicon carbide materials into one. The tensile strength at the joint is greater than 160MPa, which is comparable to the tensile strength of a single volume fraction aluminum silicon carbide material. Therefore, the bonding strength of the two meets the application requirements.

[0055] In practical applications, the aluminum silicon carbide brake disc can be further machined by turning to meet different application scenarios.

[0056] Example 1

[0057] Silicon carbide powders with particle sizes (D50) of 100μm, 50μm, 28μm, and 5μm were mixed uniformly in a ratio of 7:1:1:1. A water-based binder (aluminum dihydrogen phosphate) of 2-5% by weight of the powder was added, and the mixture was stirred in a kneader to obtain a mixture. The mixture was dried at 100℃ for 1 hour to obtain a powder. The powder was granulated and sieved through a 40-mesh sieve, and then a preform blank was obtained under a pressure of 200MPa. The preform blank was held at 500-650℃ for 1 hour to solidify, obtaining a silicon carbide preform with a density of 2.23 g / mm². 3 ;

[0058] Add silicon carbide powder with a particle size (D50) of 40-55μm to the die, with a mass of V. 合头 *50%*3.17, Silicon carbide powder with a particle size (D50) of 40-55μm is spread evenly in the inner cavity of the mold head section by vibration. The vibration frequency is 50-60Hz, the amplitude is 2-4mm, and the vibration time is 4-6min. Then, one preform is placed at the bottom of the brake disc mold, and then silicon carbide powder with a particle size (D50) of 40-55μm is added into the mold, with a mass of V. 中间层*50%*3.17, Spread silicon carbide powder with a particle size (D50) of 40-55μm evenly into the inner cavity of the middle layer of the mold by vibration. The vibration frequency is 50-60Hz, the amplitude is 2-4mm, and the vibration time is 4-6min. Finally, place another silicon carbide preform from step 1 on top of the powder.

[0059] The mold containing the silicon carbide preform and powder is preheated to 600°C and then placed in a pressure infiltration furnace. Molten aluminum alloy (700°C) is added, the furnace door is sealed, and a vacuum of 2000 Pa is created. N2 is added until the furnace pressure reaches 5 MPa, and the pressure is maintained for 60 minutes to complete the aluminum alloy infiltration process. The workpiece is removed, and the mold is disassembled to obtain a multilayer aluminum silicon carbide brake disc blank. The above aluminum silicon carbide brake disc blank is then machined into a multilayer aluminum silicon carbide brake disc of the required size by turning.

[0060] The resulting multilayer aluminum-silicon carbide brake disc has a surface layer composed of aluminum-silicon carbide material with a silicon carbide volume fraction of 70.3%, while the middle layer 22 and the joint portion are composed of aluminum-silicon carbide material with a silicon carbide volume fraction of 50%. The multilayer aluminum-silicon carbide brake disc has an impact toughness of 27.2 KJ / m. 2 The flexural strength is 405 MPa, and the density is 2.915 g / mm³. 3 The thermal conductivity is 203 W / m·K, the temperature after ten consecutive braking cycles is 480℃, and the coefficient of friction is 0.285, meeting the requirements for brake discs. Furthermore, according to the automaker's requirements, the impact toughness should be greater than or equal to 20 KJ / m. 2 The coefficient of friction should not be less than 0.26.

[0061] Example 2

[0062] Silicon carbide powders with particle sizes (D50) of 100μm, 50μm, 28μm, and 5μm were mixed uniformly in a ratio of 7:1:1:1. A water-based binder (aluminum dihydrogen phosphate) of 2-5% by weight of the powder was added, and the mixture was stirred in a kneader to obtain a mixture. The mixture was dried at 100℃ for 1 hour to obtain a powder. The powder was granulated and sieved through a 40-mesh sieve, and then a preform blank was obtained under a pressure of 300MPa. The preform blank was held at 500-650℃ for 1 hour to solidify, obtaining a silicon carbide preform with a density of 2.38 g / mm². 3 ;

[0063] Add silicon carbide powder with a particle size (D50) of 40-55μm to the die, with a mass of V. 合头*45%*3.17, Silicon carbide powder with a particle size (D50) of 40-55μm is spread evenly in the inner cavity of the mold head section by vibration. The vibration frequency is 50-60Hz, the amplitude is 2-4mm, and the vibration time is 4-6min. Then, one preform is placed at the bottom of the brake disc mold, and then silicon carbide powder with a particle size (D50) of 40-55μm is added into the mold, with a mass of V. 中间层 *45%*3.17, using vibration to spread silicon carbide powder with a particle size (D50) of 40-55μm into the inner cavity of the middle layer of the mold, the vibration frequency is 50-60Hz, the amplitude is 2-4mm, and the vibration time is 4-6min. Finally, place another silicon carbide preform from step 1 on top of the powder.

[0064] The mold containing the silicon carbide preform and powder is preheated to 600°C and then placed in a pressure infiltration furnace. Molten aluminum alloy (700°C) is added, the furnace door is sealed, and a vacuum of 2000 Pa is created. N2 is added until the furnace pressure reaches 5 MPa, and the pressure is maintained for 60 minutes to complete the aluminum alloy infiltration process. The workpiece is removed, and the mold is disassembled to obtain a multilayer aluminum silicon carbide brake disc blank. The above aluminum silicon carbide brake disc blank is then machined into a multilayer aluminum silicon carbide brake disc of the required size by turning.

[0065] The resulting multilayer aluminum-silicon carbide brake disc has a surface layer of 75% silicon carbide by volume, while the middle layer 22 and the joint portion are composed of 45% silicon carbide by volume. The multilayer aluminum-silicon carbide brake disc exhibits an impact toughness of 29.8 KJ / m. 2 The flexural strength is 392 MPa, and the density is 2.891 g / mm³. 3 The thermal conductivity is 201 W / m·K, the temperature is 480℃ after ten consecutive braking cycles, and the coefficient of friction is 0.308, which meets the requirements of the brake disc.

[0066] Example 3

[0067] Silicon carbide powders with particle sizes (D50) of 100μm, 50μm, 28μm, and 5μm were mixed uniformly in a ratio of 7:1:1:1. A water-based binder (aluminum dihydrogen phosphate) of 2-5% by weight of the powder was added, and the mixture was stirred in a kneader to obtain a mixture. The mixture was dried at 100℃ for 1 hour to obtain a powder. The powder was granulated and sieved through a 40-mesh sieve, and then a preform blank was obtained under a pressure of 300MPa. The preform blank was held at 500-650℃ for 1 hour to solidify, obtaining a silicon carbide preform with a density of 2.38 g / mm². 3 ;

[0068] Add silicon carbide powder with a particle size (D50) of 40-55μm to the die, with a mass of V. 合头*58%*3.17, Silicon carbide powder with a particle size (D50) of 40-55μm is spread evenly in the inner cavity of the mold head section by vibration. The vibration frequency is 50-60Hz, the amplitude is 2-4mm, and the vibration time is 4-6min. Then, one preform is placed at the bottom of the brake disc mold, and then silicon carbide powder with a particle size (D50) of 40-55μm is added into the mold, with a mass of V. 中间层 *58%*3.17, silicon carbide powder with a particle size (D50) of 40-55μm is spread evenly in the inner cavity of the middle layer of the mold by vibration. The vibration frequency is 50-60Hz, the amplitude is 2-4mm, and the vibration time is 4-6min. Finally, another silicon carbide preform from step 1 is placed on top of the powder.

[0069] The mold containing the silicon carbide preform and powder is preheated to 600°C and then placed in a pressure infiltration furnace. Molten aluminum alloy (700°C) is added, the furnace door is sealed, and a vacuum of 2000 Pa is created. N2 is added until the furnace pressure reaches 5 MPa, and the pressure is maintained for 60 minutes to complete the aluminum alloy infiltration process. The workpiece is removed, and the mold is disassembled to obtain a multilayer aluminum silicon carbide brake disc blank. The above aluminum silicon carbide brake disc blank is then machined into a multilayer aluminum silicon carbide brake disc of the required size by turning.

[0070] The resulting multilayer aluminum-silicon carbide brake disc has a surface layer composed of 75% silicon carbide by volume, while the middle layer 22 and the joint portion are composed of 58% silicon carbide by volume. The multilayer aluminum-silicon carbide brake disc exhibits an impact toughness of 19.5 KJ / m. 2 The flexural strength is 411 MPa, and the density is 2.96 g / mm³. 3 The thermal conductivity is 203 W / m·K, the temperature after ten consecutive braking cycles is 480℃, and the coefficient of friction is 0.308, which meets the requirements of the brake disc.

[0071] Comparative Example 1

[0072] Silicon carbide powders with particle sizes (D50) of 100 μm, 28 μm, and 5 μm were mixed evenly in a ratio of 8:1:1. A water-based binder (aluminum dihydrogen phosphate) of 2-5% by weight of the powder was added, and the mixture was stirred in a kneader to obtain a mixture. The mixture was dried at 100℃ for 1 hour to obtain a powder. The powder was granulated and sieved through a 40-mesh sieve, and then a preform blank was obtained under a pressure of 200 MPa. The preform blank was then held at 500-650℃ for 1 hour to solidify, resulting in a silicon carbide preform with a density of 1.91 g / mm². 3 ;

[0073] Add silicon carbide powder with a particle size (D50) of 40-55μm to the die, with a mass of V. 合头*50%*3.17, Silicon carbide powder with a particle size (D50) of 40-55μm is spread evenly in the inner cavity of the mold head section by vibration. The vibration frequency is 50-60Hz, the amplitude is 2-4mm, and the vibration time is 4-6min. Then, one preform is placed at the bottom of the brake disc mold, and then silicon carbide powder with a particle size (D50) of 40-55μm is added into the mold, with a mass of V. 中间层 *50%*3.17, Spread silicon carbide powder with a particle size (D50) of 40-55μm evenly into the inner cavity of the middle layer of the mold by vibration. The vibration frequency is 50-60Hz, the amplitude is 2-4mm, and the vibration time is 4-6min. Finally, place another silicon carbide preform from step 1 on top of the powder.

[0074] The mold containing the silicon carbide preform and powder is preheated to 600°C and then placed in a pressure infiltration furnace. Molten aluminum alloy (700°C) is added, the furnace door is sealed, and a vacuum of 2000 Pa is created. N2 is added until the furnace pressure reaches 5 MPa, and the pressure is maintained for 60 minutes to complete the aluminum alloy infiltration process. The workpiece is removed, and the mold is disassembled to obtain a multilayer aluminum silicon carbide brake disc blank. The above aluminum silicon carbide brake disc blank is then machined into a multilayer aluminum silicon carbide brake disc of the required size by turning.

[0075] The resulting multilayer aluminum-silicon carbide brake disc has a surface layer of 60.2% silicon carbide by volume, while the middle layer 22 and the joint portion are composed of 50% silicon carbide by volume. The multilayer aluminum-silicon carbide brake disc exhibits an impact toughness of 27.6 KJ / m. 2 The flexural strength is 395 MPa, and the density is 2.912 g / mm³. 3 The thermal conductivity is 201 W / m·K, and the temperature after ten consecutive braking cycles is 480℃. The coefficient of friction is 0.254. The coefficient of friction is too low and does not meet the requirements for brake discs.

[0076] Comparative Example 2

[0077] Silicon carbide powders with particle sizes (D50) of 100μm, 50μm, 28μm, and 5μm were mixed uniformly in a ratio of 7:1:1:1. A water-based binder (aluminum dihydrogen phosphate) of 2-5% by weight of the powder was added, and the mixture was stirred in a kneader to obtain a mixture. The mixture was dried at 100℃ for 1 hour to obtain a powder. The powder was granulated and sieved through a 40-mesh sieve, and then a preform blank was obtained under a pressure of 200MPa. The preform blank was held at 500-650℃ for 1 hour to solidify, obtaining a silicon carbide preform with a density of 2.23 g / mm². 3 ;

[0078] Add silicon carbide powder with a particle size (D50) of 40-55μm to the die, with a mass of V. 合头*60%*3.17, Silicon carbide powder with a particle size (D50) of 40-55μm is spread evenly in the inner cavity of the mold head section by vibration. The vibration frequency is 50-60Hz, the amplitude is 2-4mm, and the vibration time is 4-6min. Then, one preform is placed at the bottom of the brake disc mold, and then silicon carbide powder with a particle size (D50) of 40-55μm is added into the mold, with a mass of V. 中间层 *60%*3.17, Spread silicon carbide powder with a particle size (D50) of 40-55μm evenly into the inner cavity of the middle layer of the mold by vibration. The vibration frequency is 50-60Hz, the amplitude is 2-4mm, and the vibration time is 4-6min. Finally, place another silicon carbide preform from step 1 on top of the powder.

[0079] The mold containing the silicon carbide preform and powder is preheated to 600°C and then placed in a pressure infiltration furnace. Molten aluminum alloy (700°C) is added, the furnace door is sealed, and a vacuum of 2000 Pa is created. N2 is added until the furnace pressure reaches 5 MPa, and the pressure is maintained for 60 minutes to complete the aluminum alloy infiltration process. The workpiece is removed, and the mold is disassembled to obtain a multilayer aluminum silicon carbide brake disc blank. The above aluminum silicon carbide brake disc blank is then machined into a multilayer aluminum silicon carbide brake disc of the required size by turning.

[0080] The resulting multilayer aluminum-silicon carbide brake disc has a surface layer of 70.3% silicon carbide by volume, while the middle layer 22 and the joint portion are composed of 60% silicon carbide by volume. The multilayer aluminum-silicon carbide brake disc exhibits an impact toughness of 18.9 KJ / m. 2 The flexural strength is 412 MPa, and the density is 2.964 g / mm³. 3 It has a thermal conductivity of 203 W / m·K, a temperature of 480℃ after ten consecutive braking cycles, and a friction coefficient of 0.285. Its impact toughness is too low and does not meet the requirements for brake discs.

[0081] Comparative Example 3

[0082] Silicon carbide powders with particle sizes (D50) of 100μm, 50μm, 28μm, and 5μm were mixed uniformly in a ratio of 7:1:1:1. A water-based binder (aluminum dihydrogen phosphate) of 2-5% by weight of the powder was added, and the mixture was stirred in a kneader to obtain a mixture. The mixture was dried at 100℃ for 1 hour to obtain a powder. The powder was granulated and sieved through a 40-mesh sieve, and then a preform blank was obtained under a pressure of 200MPa. The preform blank was held at 500-650℃ for 1 hour to solidify, obtaining a silicon carbide preform with a density of 2.23 g / mm². 3 The dimensions of the precast structure are similar to those of the brake disc.

[0083] The obtained preform is placed into a brake disc mold. The mold containing the silicon carbide preform and powder is preheated to 600°C, then placed in a pressure infiltration furnace. Molten aluminum alloy (temperature 700°C) is added, the furnace door is sealed, a vacuum of 2000 Pa is drawn, and N2 is added until the furnace pressure reaches 5 MPa. The pressure is maintained for 60 minutes to complete the aluminum alloy infiltration process. The workpiece is removed, and the mold is disassembled to obtain a multi-layer aluminum silicon carbide brake disc blank. The above aluminum silicon carbide brake disc blank is machined into a single-layer aluminum silicon carbide brake disc of the required size by turning.

[0084] The obtained single-layer aluminum silicon carbide brake disc is an aluminum silicon carbide material with a silicon carbide volume fraction of 70.3%, and its impact toughness is 14.3 KJ / m. 2 The flexural strength is 398 MPa, and the density is 3.01 g / mm³. 3 It has a thermal conductivity of 196 W / m·K, a temperature of 480℃ after ten consecutive braking cycles, and a friction coefficient of 0.285. Its impact toughness is too low and does not meet the requirements for brake discs.

[0085] Comparative Example 4

[0086] Add silicon carbide powder with a particle size (D50) of 40-55 μm to the mold, with a mass of V. 模具 *50%*3.17, silicon carbide powder with a particle size (D50) of 40-55μm is spread evenly inside the mold cavity by vibration at a frequency of 50-60Hz, an amplitude of 2-4mm, and a vibration time of 4-6min. The mold containing the silicon carbide powder is preheated to 600℃ and then placed in a pressure infiltration furnace. Molten aluminum alloy (temperature 700℃) is added, the furnace door is sealed, and a vacuum is drawn to 2000Pa. N2 is added until the pressure inside the furnace reaches 5MPa, and the pressure is maintained for 60min to complete the aluminum alloy infiltration process. The workpiece is removed, and the mold is disassembled to obtain a single-layer aluminum silicon carbide brake disc blank. The above aluminum silicon carbide brake disc blank is machined into a single-layer aluminum silicon carbide brake disc of the required size by turning.

[0087] The obtained single-layer aluminum silicon carbide brake disc is an aluminum silicon carbide material with a silicon carbide volume fraction of 50%, while the multi-layer aluminum silicon carbide brake disc has an impact toughness of 27.2 KJ / m. 2 The flexural strength is 398 MPa, and the density is 2.912 g / mm³. 3 The thermal conductivity is 195 W / m·K, and the temperature after ten consecutive braking cycles is 480℃. The coefficient of friction is 0.224. The coefficient of friction is too low and does not meet the requirements for brake discs.

[0088] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an aluminum silicon carbide brake disc, characterized in that, This material is used to prepare an aluminum silicon carbide brake disc, wherein the aluminum silicon carbide brake disc includes: a disc body (2) and a head (1) coaxially connected to the disc body (2). The disc body (2) is a multi-layer structure with a total thickness between 28 and 32 mm, including an upper surface layer (21), a middle layer (22) and a lower surface layer (23). The upper surface layer (21) and the lower surface layer (23) are both aluminum silicon carbide materials with a SiC volume fraction of 70 to 75% and a thickness of 2 to 4 mm, respectively. The middle layer (22) and the head (1) are both aluminum silicon carbide materials with a SiC volume fraction of 45 to 58%. The method for preparing aluminum silicon carbide brake discs includes the following steps: The mixture of SiC powder and binder is dried, pressed, and cured to obtain a SiC preform with a porosity of 25-30%. The mixture of SiC powder and binder is made by mixing SiC powder with particle sizes of 100μm, 50μm, 28μm and 5μm with binder, and the mixed SiC powder with particle sizes of 100μm, 50μm, 28μm and 5μm is mixed evenly in a ratio of 7:1:1:

1. SiC powder is filled into the mold head, and the porosity of SiC after filling is 42~55%; a SiC preform matching the shape and size of the bottom layer of the mold head is placed in it; SiC powder is filled into the middle layer of the mold head, and the porosity of SiC after filling is 42~55%; another SiC preform matching the shape and size of the top layer of the mold head is placed in it. An aluminum alloy is impregnated, and after demolding, an aluminum silicon carbide brake disc is obtained, wherein the aluminum alloy in the aluminum silicon carbide brake disc is a continuously distributed phase; The process of filling the intermediate layer of the head mold or the disc mold with SiC powder includes filling the intermediate layer of the head mold or the disc mold with SiC powder of 40~55μm particle size by adding and vibrating at the same time, wherein the vibration frequency is 50-60Hz and the amplitude is 2-4mm. Silicon carbide powder, with a mass of V, is added to the mold. 合头 *φB*3.17; where V 合头 φB is the volume of the mating part in the mold, φB is the volume fraction of silicon carbide at that location, and 3.17 is the theoretical density of silicon carbide. Silicon carbide powder with a mass of V is added to the intermediate layer mold. 中间层 *φB*3.17; where V 中间层 φB is the volume of the middle layer of the mold, φB is the volume fraction of silicon carbide at that location, and 3.17 is the theoretical density of silicon carbide.

2. The method for preparing an aluminum silicon carbide brake disc according to claim 1, characterized in that, The aluminum element in the aluminum silicon carbide brake disc exists in the form of a continuously distributed aluminum alloy.

3. The method for preparing an aluminum silicon carbide brake disc according to claim 1, characterized in that, The aluminum-silicon carbide brake disc has a friction coefficient ≥0.28 at 480℃; the impact toughness of the aluminum-silicon carbide brake disc is ≥26KJ / m. 2 .

4. The method for preparing an aluminum silicon carbide brake disc according to claim 1, characterized in that, The curing process includes: holding the pressed preform at 500-650°C for 45-75 minutes.

5. The method for preparing an aluminum silicon carbide brake disc according to claim 1, characterized in that, Impregnated aluminum alloys include: aluminum alloys impregnated under pressure in an inert gas atmosphere.

6. The method for preparing an aluminum silicon carbide brake disc according to claim 5, characterized in that, The aluminum alloy added during the pressure impregnation process is molten aluminum alloy, the impregnation pressure is 4-6 MPa, and the holding time is 30-60 min.

7. The method for preparing an aluminum silicon carbide brake disc according to claim 5, characterized in that, Before pressure impregnation, the SiC in the head mold and the disc mold is preheated to 580~650°C.

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