Particle-reinforced aluminum-based composite material, brake disc and preparation method and application of particle-reinforced aluminum-based composite material and brake disc

Abstract

The invention provides a particle-reinforced aluminum-based composite material, a brake disc and a preparation method and application of the particle-reinforced aluminum-based composite material and the brake disc. The particle reinforced aluminum-based composite material comprises a matrix alloy and a reinforced phase, the matrix alloy is prepared from the following components in percentage by mass: 6.5 wt% to 7.5 wt% of Si, 4.0 wt% to 5.5 wt% of Cu, 0.7 wt% to 1.0 wt% of Mg, 0.1 wt% to 0.25 wt% of Mn, 0.05 wt% to 0.3 wt% of Ni, 0.05 wt% to 0.2 wt% of Zr and the balance of Al; based on the volume of the particle reinforced aluminum matrix composite being 100%, the proportion of the reinforced phase is 10 vol%-30 vol%; the reinforcing phase is SiC particles. The prepared brake disc has high compactness, stable high wear resistance, excellent high-temperature short-time tensile property and good and stable structure property after long-time thermal exposure.

Description

Technical Field

[0001] The present invention belongs to the field of aluminum-based composite materials, and in particular relates to a particle-reinforced aluminum-based composite material, a brake disc, and a preparation method and application thereof. Background Art

[0002] Lightweighting of rail transit is an important direction for its development at this stage, and it is of particular practical significance for reducing vehicle weight, increasing speed, reducing noise, and lowering energy consumption. Using aluminum alloy materials to replace the currently widely used gray cast iron and cast steel materials to manufacture automobile and rail transit brake discs can meet the requirements of lightweighting. Among them, SiC particle-reinforced aluminum-based composite materials not only have the characteristics of low density and good thermal conductivity of the aluminum matrix, but also have the advantages of high wear resistance, high hardness, and low expansion coefficient of the SiC particle components. On the premise of meeting the requirements of use, using SiCp / Al composite brake discs to replace traditional cast iron or cast steel brake discs can reduce the weight of the brake discs by 50%-60%, and have the advantages of no braking noise, no hot spots, and long service life, thus having broad application prospects in rail transit trains.

[0003] However, the aluminum-based composite materials currently used in rail transit are primarily SiCp / A356 composites, which have certain limitations and are only suitable for urban rail transit systems with speeds below 120 km / h. For intercity or urban trains with higher speeds, the high temperatures generated during braking can easily cause the SiCp / A356 composite material to soften, resulting in reduced braking performance and lower high-temperature performance. The braking performance of rail transit brake discs is directly related to vehicle safety. In rail transit systems, due to frequent braking and high speeds, the surface temperature of the brake discs can reach 300-400°C during braking. Ordinary aluminum alloys struggle to maintain high performance at these temperatures and are prone to softening.

[0004] CN113215448A introduces elements such as Fe and Mg into an Al-Si alloy to produce a cast aluminum alloy with excellent high-temperature performance. However, the alloy's reinforcing phase becomes coarse at temperatures exceeding 200°C, sharply reducing the strengthening effect. CN102212730A uses an Al-Si alloy as a matrix to produce a SiC particle-reinforced aluminum-based composite material. This composite material maintains high hardness at 200°C, but its performance degrades sharply as the temperature continues to rise, making it difficult to use in high-speed rail transit braking systems exceeding 120 km / h. CN109022948A discloses a SiC particle-reinforced aluminum-based composite material with an Al-Si-Cu alloy as the matrix. The composite material still maintains a high hardness at a high temperature of 200°C. However, as the temperature continues to rise, the material properties will decay sharply. CN102634706A discloses a high-strength, high-toughness, corrosion-resistant Al-Cu-Mg aluminum alloy. This technical solution prepares an aluminum alloy with high strength and good plasticity by adjusting the mass ratio of alloying elements in the Al-Cu-Mg alloy. However, the high-temperature resistant phase strengthening phase in the alloy is mainly the θ phase, which will become coarse at a high temperature of 300°C, reducing the strengthening effect.

[0005] Therefore, in order to achieve energy conservation, weight reduction and efficiency improvement in rail transit systems while ensuring the high-temperature performance of aluminum alloy composite materials, it is necessary to improve the composition of the matrix aluminum alloy and produce aluminum alloy composite materials with excellent high-temperature performance and high wear resistance, so that rail transit brake discs can still meet service requirements in high-temperature environments. Summary of the Invention

[0006] In order to solve the above technical problems, the purpose of the present invention is to provide a particle-reinforced aluminum-based composite material, a brake disc and a preparation method and application thereof.

[0007] To achieve the above object, the present invention provides a particle reinforced aluminum matrix composite material, wherein the particle reinforced aluminum matrix composite material comprises a matrix alloy and a reinforcement phase;

[0008] Measured by mass percentage, the matrix alloy comprises: Si 6.5wt%-7.5wt%, Cu 4.0wt%-5.5wt%, Mg 0.7wt%-1.0wt%, Mn 0.1wt%-0.25wt%, Ni 0.05wt%-0.3wt%, Zr0.05wt%-0.2wt%, and the balance is Al; based on the volume of the particle-reinforced aluminum-based composite material as 100%, the proportion of the reinforcing phase is 10vol%-30vol%; the reinforcing phase is SiC particles.

[0009] According to a specific embodiment of the present invention, preferably, the average particle size of the SiC particles is 3-20 μm.

[0010] According to a specific embodiment of the present invention, preferably, based on 100% by volume of the particle-reinforced aluminum-based composite material, the SiC particles account for 20 vol%-30 vol%, and have an average particle size of 10-15 μm.

[0011] According to a specific embodiment of the present invention, preferably, by mass percentage, the base alloy comprises: Si 6.5wt%-7.0wt%, Cu 4.0wt%-5.0wt%, Mg 0.8wt%-0.9wt%, Mn 0.15wt%-0.25wt%, Ni 0.05wt%-0.2wt%, Zr 0.05wt%-0.15wt%, and the balance is Al. More preferably, by mass percentage, the base alloy comprises: Si 6.5wt%-6.8wt%, Cu 4.0wt%-4.4wt%, Mg 0.8wt%-0.9wt%, Mn 0.2wt%, Ni 0.1wt%, Zr 0.1wt%, and the balance is Al.

[0012] The present invention forms multiple strengthening phases of Mg2Si, Cu4Mg5Si4Al and Al2Cu in the matrix by designing a reasonable combination of Si, Cu and Mg. Among them, the heat resistance of the Cu4Mg5Si4Al phase is better than that of Al2Cu, and the content of the Cu4Mg5Si4Al phase is relatively high, thereby increasing the strengthening effect of the high-temperature resistant phase; through the synergistic effect of the high-temperature resistant phase in the matrix alloy and SiC with equally good heat resistance, the heat resistance of the particle-reinforced aluminum-based composite material is improved.

[0013] The present invention also provides a method for preparing a brake disc, wherein the method uses the above-mentioned particle-reinforced aluminum-based composite material as a raw material and comprises the following steps:

[0014] Step 1: Mix pure aluminum, aluminum-silicon alloy, aluminum-copper alloy, aluminum-manganese alloy, aluminum-nickel alloy, and aluminum-zirconium alloy and heat them up. After all the alloys are melted, add pure magnesium and keep the temperature to obtain a matrix alloy melt.

[0015] Step 2: refining the matrix alloy melt to obtain a refined melt;

[0016] Step 3: performing a first stirring on the refined melt, and then adding the pretreated SiC particles; after the addition is completed, performing a second stirring on the melt to obtain a composite material melt;

[0017] Step 4: heating the composite material melt to perform casting molding, and then performing T6 heat treatment to obtain a heat-resistant aluminum-based composite material casting; and performing mechanical processing to obtain a brake disc.

[0018] According to a specific embodiment of the present invention, preferably, the temperature of the melt during the first stirring of the melt is a first temperature, and the first temperature is 630-680°C.

[0019] According to a specific embodiment of the present invention, preferably, the first stirring condition is: stirring at a rotation speed of 400-600 rad / min for 2-5 min.

[0020] According to a specific embodiment of the present invention, preferably, the temperature of the melt during the second stirring of the melt is a second temperature, and the second temperature is 600-640°C.

[0021] According to a specific embodiment of the present invention, preferably, the second stirring condition is: stirring at a rotation speed of 600-650 rad / min for 15-60 min in a semi-solid state.

[0022] According to a specific embodiment of the present invention, preferably, in step 1, the temperature at which the pure aluminum, aluminum-silicon alloy, aluminum-copper alloy, aluminum-manganese alloy, aluminum-nickel alloy, and aluminum-zirconium alloy are mixed and heated is 660-750°C.

[0023] In the above preparation method, preferably, in step 1, the insulation time is 5-10 minutes.

[0024] In the above preparation method, preferably, the aluminum-silicon alloy is Al-24Si, the aluminum-copper alloy is Al-30Cu, the aluminum-manganese alloy is Al-40Mn, the aluminum-nickel alloy is Al-10Ni, and the aluminum-zirconium alloy is Al-10Zr.

[0025] In the above preparation method, preferably, the refining step comprises: deslagging the base alloy melt, adding a refining agent for refining and degassing, stirring the melt for 3-10 minutes, deslagging, and obtaining a refined melt.

[0026] In some specific embodiments, preferably, the refining agent includes hexachloroethane. During refining, process parameters commonly used in the art can be used and conventionally selected according to actual needs.

[0027] In the above preparation method, preferably, the pretreatment step is to subject the SiC particles to a high temperature oxidation treatment at 1200-1300° C. for 2-4 hours.

[0028] In the above preparation method, preferably, the casting step is: first preheating the casting mold to 200-300°C, then heating the stirred heat-resistant composite material melt to 640-660°C and casting it into the mold for casting.

[0029] In the above preparation method, the mechanical processing step is a conventional operation in this field and can be conventionally adjusted according to actual needs to obtain the desired shape.

[0030] The present invention also provides a brake disc, which is prepared by the above preparation method.

[0031] According to a specific embodiment of the present invention, preferably, the density of the brake disc is ≥99.8%.

[0032] In the present invention, the material of the brake disc has a tensile strength of more than 340 MPa and a hardness of more than 190 HBW at room temperature; further, the material of the brake disc maintains a tensile strength of more than 170 MPa at 300°C and a hardness of more than 170 HBW after heat exposure at 300°C for 20 minutes.

[0033] The present invention also provides an application of the above-mentioned brake disc on an intercity train or an urban train, wherein the maximum operating speed of the intercity train or the urban train is 120 km / h to 160 km / h, preferably 160 km / h.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention ensures that the composite material has excellent performance matching by finely optimizing the composition range and ratio of each element of the matrix alloy in the particle-reinforced aluminum-based composite material; the matrix alloy composition is independently designed by analyzing the phase diagram of the Al-Si-Cu-Mg alloy; and by selecting suitable elements and reinforcing phase content, a brake disc of the Al-Si-Cu-Mg matrix alloy with excellent high-temperature resistance is designed and prepared, achieving significant improvement in heat resistance while still maintaining high room-temperature strength, fracture toughness and fatigue performance.

[0036] The brake disc preparation method provided by the present invention solves the problems of uneven SiC particle distribution, loose interface bonding, and high porosity that are easily encountered in the preparation process of high-volume SiCp / Al-Si-Cu-Mg brake disc materials by optimizing process parameters and various working steps. The prepared brake disc has a uniform reinforcement phase distribution, excellent heat resistance, excellent room temperature mechanical properties, high density, stable high wear resistance, excellent high-temperature short-time tensile properties, and good and stable organizational properties after long-term heat exposure. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is the microstructure of the brake disc prepared in Example 1.

[0038] Figure 2 This is the microstructure of the brake disc prepared in Example 2.

[0039] Figure 3 This is the microstructure of the brake disc prepared in Comparative Example 1.

[0040] Figure 4 This is the microstructure of the brake disc prepared in Comparative Example 2.

[0041] Figure 5 This is the microstructure of the brake disc prepared in Comparative Example 3. DETAILED DESCRIPTION

[0042] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0043] Example 1

[0044] This embodiment provides a particle-reinforced aluminum-based composite material and a brake disc, specifically as follows:

[0045] (1) The particle-reinforced aluminum-based composite material includes a matrix alloy and a reinforcing phase; wherein, in terms of mass percentage, the matrix alloy contains: Si 6.8wt%, Cu 4.4wt%, Mg 0.8wt%, Mn 0.2wt%, Ni 0.1wt%, Zr 0.1wt%, and the balance is Al; the reinforcing phase is micron-sized SiC particles, wherein, based on the volume of the particle-reinforced aluminum-based composite material being 100%, the SiC particles account for 20vol%, and have an average particle size of 13μm.

[0046] (2) The brake disc is prepared using particle-reinforced aluminum-based composite materials as raw materials. The specific steps are as follows:

[0047] Step 1: In a vacuum melting furnace, add industrial pure aluminum, aluminum silicon alloy (Al-24Si), aluminum copper alloy (Al-30Cu), aluminum manganese alloy (Al-40Mn), aluminum nickel alloy (Al-10Ni), and aluminum zirconium alloy (Al-10Zr) according to the set mass percentage of each element component, and heat to 750°C; after the alloy is completely melted, add pure magnesium (the burnout of pure Mg is based on 30% of the ingredients), and keep the temperature for 10 minutes to obtain a matrix alloy melt;

[0048] Step 2: Deslagging the base alloy melt, adding a refining agent (hexachloroethane) to perform refining and degassing, stirring the melt for 4 minutes, and deslagging to obtain a refined melt;

[0049] Step 3: Turn on the stirring device and control the first temperature of the melt to 660°C, apply strong first stirring to the melt at the first temperature, the stirring speed is 500rad / min, and the duration is 4min; then add pretreated SiC particles according to the set reinforcement phase volume ratio, wherein the pretreatment step is to oxidize the SiC particles at a high temperature of 1200°C for 3 hours; after the addition is completed, the second temperature of the melt is controlled to 610°C, and the melt is stirred for a second time in a semi-solid state at a stirring speed of 600rad / min for 15min to obtain a composite material melt;

[0050] Step 4: Preheat the casting mold to 300°C, then heat the composite material melt to 640°C and cast it into the mold for casting, and then perform T6 heat treatment to obtain a heat-resistant aluminum-based composite material casting; the T6 heat treatment process is: solution treatment at 500°C for 2 hours, followed by water cooling at 180°C for 12 hours; and mechanical processing to obtain a brake disc.

[0051] The microstructure of the brake disc prepared in this embodiment is as follows Figure 1 As shown, from Figure 1 It can be seen that the SiCp particles are evenly dispersed in the matrix alloy. The density is measured by the drainage method, and the density reaches 99.86%.

[0052] Mechanical property testing of the brake disc material in this embodiment showed that the material had a tensile strength of 340 MPa and a hardness of 193 HBW at room temperature. Furthermore, at a high temperature of 300°C, the tensile strength of the brake disc material was stably maintained above 170 MPa. The change in hardness after heat exposure is shown in Table 1.

[0053] Table 1. Hardness changes before and after heat exposure of Example 1

[0054]

[0055] As can be seen from Table 1, the hardness of the brake disc prepared in this embodiment can still maintain a relatively high hardness value after a certain period of high-temperature exposure. According to the formula: Change rate = (Hardness at room temperature - Hardness after 20 minutes of heat exposure) / Hardness at room temperature × 100%, it can be concluded that after 20 minutes of heat exposure, the decrease in hardness at different temperatures is relatively small. At 300°C, the decrease can still be maintained within 10%, showing excellent heat exposure performance.

[0056] Due to the improvement in high-temperature mechanical properties, the brake disc and the dual brake pad prepared in this embodiment can form a stable friction layer during the braking process. At an initial speed of 160 km / h and a disc surface temperature higher than 300°C, the average friction coefficient of the brake disc can be stabilized within the range of 0.321-0.340 under multiple braking dynamic tests.

[0057] Example 2

[0058] This embodiment provides a particle-reinforced aluminum-based composite material and a brake disc, specifically as follows:

[0059] (1) The particle-reinforced aluminum-based composite material includes a matrix alloy and a reinforcing phase; wherein, in terms of mass percentage, the matrix alloy contains: Si 6.5wt%, Cu 4.0wt%, Mg 0.9wt%, Mn 0.2wt%, Ni 0.1wt%, Zr 0.1wt%, and the balance is Al; the reinforcing phase is micron-sized SiC particles, wherein, based on the volume of the particle-reinforced aluminum-based composite material being 100%, the SiC particles account for 30vol%, and have an average particle size of 11μm.

[0060] (2) The brake disc is prepared using particle-reinforced aluminum-based composite materials as raw materials. The specific steps are as follows:

[0061] Step 1: In a vacuum melting furnace, add industrial pure aluminum, aluminum silicon alloy (Al-24Si), aluminum copper alloy (Al-30Cu), aluminum manganese alloy (Al-40Mn), aluminum nickel alloy (Al-10Ni), and aluminum zirconium alloy (Al-10Zr) according to the set mass percentage of each element component, and heat to 720°C; after the alloy is completely melted, add pure magnesium (the burnout of pure Mg is based on 30% of the ingredients), and keep the temperature for 10 minutes to obtain a matrix alloy melt;

[0062] Step 2: Deslagging the base alloy melt, adding a refining agent (hexachloroethane) to perform refining and degassing, stirring the melt for 5 minutes, and deslagging to obtain a refined melt;

[0063] Step 3: Turn on the stirring device and control the first temperature of the melt to 658°C, apply strong first stirring to the melt at the first temperature, the stirring speed is 500rad / min, and the duration is 4min; then add pretreated SiC particles according to the set volume ratio of the reinforcement phase, wherein the pretreatment step is to oxidize the SiC particles at a high temperature of 1200°C for 3 hours; after the addition is completed, the second temperature of the melt is controlled to 607°C, and the melt is stirred for a second time in a semi-solid state at a stirring speed of 650rad / min for 18min to obtain a composite material melt;

[0064] Step 4: Preheat the casting mold to 300°C, then heat the composite material melt to 642°C and cast it into the mold for casting, and then perform T6 heat treatment to obtain a heat-resistant aluminum-based composite material casting; the T6 heat treatment process is: solution treatment at 500°C for 2 hours, followed by water cooling at 180°C for 12 hours; and mechanical processing to obtain a brake disc.

[0065] The microstructure of the brake disc prepared in this embodiment is as follows Figure 2 As shown, from Figure 2 It can be seen that the SiCp particles are evenly dispersed in the matrix alloy. The density is measured by the drainage method, and the density reaches 99.89%.

[0066] Mechanical property testing of the brake disc material in this embodiment showed that the material had a tensile strength of 360 MPa and a hardness of 203 HBW at room temperature. Furthermore, at a high temperature of 300°C, the tensile strength of the brake disc material was stably maintained above 172 MPa. The change in hardness after heat exposure is shown in Table 2.

[0067] Table 2. Hardness changes before and after heat exposure of Example 2

[0068]

[0069] As can be seen from Table 2, the hardness of the brake disc prepared in this embodiment can still maintain a relatively high hardness value after a certain period of high-temperature exposure. According to the formula: Change rate = (Hardness at room temperature - Hardness after 20 minutes of heat exposure) / Hardness at room temperature × 100%, it can be concluded that after 20 minutes of heat exposure, the decrease in hardness at different temperatures is relatively small. At 300°C, the decrease can still be maintained within 10%, showing excellent heat exposure performance.

[0070] Due to the improvement in high-temperature mechanical properties, the brake disc and the dual brake pad prepared in this embodiment can form a stable friction layer during the braking process. At an initial speed of 160 km / h and a disc surface temperature higher than 300°C, the average friction coefficient of the brake disc can be stabilized within the range of 0.333-0.350 under multiple braking dynamic tests.

[0071] Comparative Example 1

[0072] This comparative example provides a brake disc, which uses the same materials and proportions as Example 2 and is carried out with reference to the steps in Example 2, except that the first stirring is omitted, the second temperature of the melt is changed to 700°C, and the second stirring is carried out for 30 minutes. The remaining steps remain unchanged to obtain a brake disc.

[0073] The microstructure of the brake disc prepared in this comparative example is as follows Figure 3 As shown, from Figure 3 It can be seen that there is obvious agglomeration of SiCp particles in the tissue. The density is measured by the water displacement method, and the density is only 98.6%.

[0074] Mechanical property testing of the brake disc material in this comparative example showed that the tensile strength of the brake disc material at room temperature was only 216 MPa and the hardness was only 182 HBW; further, at a high temperature of 300°C, the tensile strength of the brake disc material was only 135 MPa.

[0075] Comparative Example 2

[0076] This comparative example provides a SiCp / Al-Cu-Mg system brake disc, which is carried out according to the steps in Example 1, except that the mass percentages of the elements in the matrix alloy in the particle-reinforced aluminum-based composite material are changed. In terms of mass percentage, the matrix alloy comprises: 4.5wt% Cu, 0.7wt% Mg, 0.2wt% Mn, and the balance Al. The remaining steps remain unchanged to obtain a SiCp / Al-Cu-Mg system brake disc.

[0077] The microstructure of the SiCp / Al-Cu-Mg system brake disc prepared in this comparative example is as follows: Figure 4 As shown, from Figure 4 It can be seen that SiCp particles have obvious agglomeration phenomenon. The density is measured by drainage method and the density is only 99.2%.

[0078] Mechanical property testing of the brake disc material in this comparative example showed that the tensile strength of the brake disc material at room temperature was only 256 MPa and the hardness was only 146 HBW; further, at a high temperature of 300°C, the tensile strength of the brake disc material was only 124 MPa.

[0079] Comparative Example 3

[0080] This comparative example provides a brake disc, which is carried out according to the steps in Example 1, except that: in the particle-reinforced aluminum-based composite material, the particle size of the reinforcing phase is changed. Based on the volume of the particle-reinforced aluminum-based composite material as 100%, the proportion of the reinforcing phase SiC particles in this comparative example is 20 vol%, and the average particle size is 2 μm; the remaining steps remain unchanged to obtain a brake disc.

[0081] The microstructure of the brake disc prepared in this comparative example is as follows Figure 5 As shown, from Figure 5 It can be seen that the reinforcement phase is severely agglomerated in the matrix, and its proportion is far lower than the expected addition ratio. The density is measured by the drainage method, and the density is only 99.1%. It can be seen that the particle size of SiC particles can affect the proportion that can be added.

[0082] Mechanical property testing of the brake disc material in this comparative example showed that the tensile strength of the brake disc material at room temperature was only 226 MPa and the hardness was only 132 HBW; further, at a high temperature of 300°C, the tensile strength of the brake disc material was only 113 MPa.

Claims

1. A particle-reinforced aluminum matrix composite material, wherein: The particle reinforced aluminum matrix composite material comprises a matrix alloy and a reinforcement phase; Calculated by mass percentage, the matrix alloy comprises: Si 6.5wt%-7.5wt%, Cu 4.0wt%-5.5wt%, Mg0.7wt%-1.0wt%, Mn 0.1wt%-0.25wt%, Ni 0.05wt%-0.3wt%, Zr 0.05wt%-0.2wt%, and the balance is Al; Taking the volume of the particle-reinforced aluminum-based composite material as 100%, the proportion of the reinforcement phase is 10 vol% to 30 vol%; the reinforcement phase is SiC particles.

2. The particle-reinforced aluminum-based composite material according to claim 1, wherein: The average particle size of the SiC particles is 3-20 μm; Preferably, based on 100% volume of the particle-reinforced aluminum-based composite material, the SiC particles account for 20 vol%-30 vol%, and have an average particle size of 10-15 μm.

3. The particle-reinforced aluminum-based composite material according to claim 1, wherein: Calculated by mass percentage, the matrix alloy comprises: Si 6.5wt%-7.0wt%, Cu 4.0wt%-5.0wt%, Mg 0.8wt%-0.9wt%, Mn 0.15wt%-0.25wt%, Ni 0.05wt%-0.2wt%, Zr 0.05wt%-0.15wt%, and the balance is Al.

4. A method for preparing a brake disc, wherein: The preparation method uses the particle-reinforced aluminum-based composite material according to any one of claims 1 to 3 as a raw material, and comprises the following steps: Step 1: Mix pure aluminum, aluminum-silicon alloy, aluminum-copper alloy, aluminum-manganese alloy, aluminum-nickel alloy, and aluminum-zirconium alloy and heat them up. After all the alloys are melted, add pure magnesium and keep the temperature to obtain a matrix alloy melt. Step 2: refining the matrix alloy melt to obtain a refined melt; Step 3: performing a first stirring on the refined melt, and then adding the pretreated SiC particles; after the addition is completed, performing a second stirring on the melt to obtain a composite material melt; Step 4: heating the composite material melt to perform casting molding, and then performing T6 heat treatment to obtain a heat-resistant aluminum-based composite material casting; and performing mechanical processing to obtain a brake disc.

5. The preparation method according to claim 4, wherein The melt temperature during the first stirring of the melt is a first temperature, and the first temperature is 630-680° C.; And / or, the first stirring condition is: stirring at a rotation speed of 400-600 rad / min for 2-5 min.

6. The preparation method according to claim 4, wherein The melt temperature during the second stirring of the melt is a second temperature, and the second temperature is 600-640° C.; And / or, the second stirring condition is: stirring at a rotation speed of 600-650 rad / min for 15-60 min in a semi-solid state.

7. The preparation method according to claim 4, wherein In step 1, pure aluminum, aluminum-silicon alloy, aluminum-copper alloy, aluminum-manganese alloy, aluminum-nickel alloy, and aluminum-zirconium alloy are mixed and heated to a temperature of 660-750°C.

8. A brake disc prepared by the preparation method according to any one of claims 4 to 7.

9. The brake disc according to claim 8, wherein: The density of the brake disc is ≥99.8%.

10. Application of the brake disc according to claim 8 or 9 on an intercity train or an urban train, wherein: The maximum operating speed of the intercity train or urban train is 120km / h to 160km / h, preferably 160km / h.

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