Heat-resistant high-strength passenger car aluminum matrix composite brake disc and preparation method thereof
By employing Al-Fe-V-Si aluminum alloy and ceramic reinforcing particles in aluminum-based composite brake discs, the problems of casting defects and easy fracture at high temperatures were solved, resulting in improved strength and heat resistance of the brake discs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUNAN UNIV
- Filing Date
- 2024-12-31
- Publication Date
- 2026-08-04
AI Technical Summary
Existing aluminum-based composite brake discs suffer from casting defects such as porosity, shrinkage, and uneven distribution of reinforcing phases during the manufacturing process, which lead to a decline in mechanical properties and make them prone to fracture at high temperatures, as well as insufficient toughness.
Al-Fe-V-Si aluminum alloy is used as the friction layer matrix, combined with ceramic reinforcing particles. The matrix layer and the friction layer are bonded together by friction stir welding to form a dense solid-phase weld, which refines the grain structure and improves the heat resistance and strength of the material.
It significantly improves the heat resistance and high-temperature mechanical properties of brake discs, enhances the strength, modulus, wear resistance and thermal expansion of the material, and ensures the stability and reliability of brake discs at high temperatures.
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Figure CN119934176B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to an aluminum-based composite material brake disc, specifically to a heat-resistant, high-strength aluminum-based composite material brake disc for passenger vehicles and its preparation method, belonging to the field of brake disc technology. Background Technology
[0002] The transportation industry is developing rapidly, but energy shortages pose a serious challenge, making energy conservation one of its primary development goals. For automobiles, there are two main measures: firstly, vigorously developing new energy vehicles; and secondly, reducing vehicle weight. Replacing currently widely used cast iron brake discs with lightweight aluminum-based composite materials can significantly reduce weight, offering a very promising prospect. Furthermore, aluminum-based composite brake discs possess advantages such as light weight, good friction and wear resistance, excellent thermal conductivity, and good resistance to thermal fatigue, giving them a strong competitive advantage in automotive brake disc applications.
[0003] Current research on composite material brake disc fabrication mainly employs stir casting to prepare integrated composite brake discs. However, due to the high surface tension and poor surface wettability of ceramic particles, composite materials prepared by stir casting suffer from casting defects such as porosity, shrinkage, and uneven distribution of the reinforcing phase, which adversely affect the material's mechanical properties. Furthermore, the insufficient toughness of aluminum-based composites means that during braking, broken reinforcing phase particles can lead to crack initiation and propagation, further accelerating brake disc fracture failure. Summary of the Invention
[0004] To address the problems existing in the prior art, the first objective of this invention is to provide a heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles. This brake disc, based on the synergistic effect between the matrix layer and the friction layer, ensures the specific strength and specific stiffness of the brake disc while significantly improving its heat resistance, especially its mechanical properties under high-temperature conditions above 300°C. The friction layer of this brake disc uses an Al-Fe-V-Si aluminum alloy as the matrix, utilizing the finely dispersed Al atoms within it... 12 The (Fe,V)3Si heat-resistant phase achieves high-temperature strengthening, and combined with ceramic reinforcing particles, further improves the material's strength, modulus, wear resistance, fatigue resistance, and thermal expansion properties.
[0005] The second objective of this invention is to provide a method for preparing a heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles. This method uses friction stir welding to bond the substrate layer and the friction layer together. The process generates heat through friction between the high-speed rotating stirring head and the workpiece, causing the material to be welded to soften locally. As the stirring head moves along the welding interface, the already plasticized material flows from the front end to the rear end of the stirring head under the action of the rotational friction force of the stirring head, and forms a dense solid-phase weld under the extrusion of the stirring head. In addition, during the friction stir process, the original defects near the contact surface between the substrate layer and the friction layer are destroyed, thereby obtaining a finer and more uniform grain structure.
[0006] To achieve the above-mentioned technical objectives, the present invention provides a heat-resistant and high-strength aluminum-based composite brake disc for passenger vehicles, comprising: an aluminum alloy matrix layer and a composite friction layer formed by friction welding; the composite friction layer comprises an Al-Fe-V-Si aluminum alloy and reinforcing particles; the reinforcing particles are at least one of SiC, BN and TiC.
[0007] The brake disc provided by this invention combines an aluminum alloy substrate layer and a composite material friction layer through friction welding. This not only ensures good overall toughness of the brake disc but also improves wear resistance and heat resistance, resulting in better overall mechanical properties and increased reliability of the aluminum-based composite brake disc. The Al-Fe-V-Si aluminum alloy in the composite material friction layer contains a high volumetric Al content. 12 (Fe,V)3Si nano-dispersed phase can improve the high-temperature performance of the friction layer, and the addition of reinforcing particles can further improve the alloy's strength, modulus, wear resistance, fatigue resistance and thermal expansion.
[0008] As a preferred embodiment, the tensile strength Rm of the substrate layer is ≥200 MPa, the elongation after fracture A is ≥9%, and the hardness is ≥65 HV0.2; the aluminum alloy substrate layer is ZL101 aluminum alloy.
[0009] As a preferred embodiment, the reinforcing particles account for 15-30% of the total mass of the composite friction layer.
[0010] As a preferred embodiment, the reinforcing particles have a particle size of 5~30μm and are normally distributed.
[0011] As a preferred embodiment, the Al-Fe-V-Si aluminum alloy comprises the following components by mass percentage: Fe 8.3~8.5%, Si 1.0~1.9%, V 1.2~1.4%, Zn 0.2~0.3%, Cr 0.1~0.3%, Mn 0.1~0.3%, Ti 0.1~0.3%, with the balance being aluminum.
[0012] As a preferred embodiment, the Al-Fe-V-Si aluminum alloy is composed of the following components by mass percentage: Fe 8.42%, Si 1.93%, V 1.29%, Zn 0.25%, Cr 0.1%, Mn 0.1%, Ti 0.1%, with the balance being aluminum.
[0013] As a preferred embodiment, the friction layer has a tensile strength Rm ≥ 380 MPa, elongation after fracture A ≥ 3%, hardness ≥ 140 HV0.2, and density of 2.9~3.0 g / cm³. 3 .
[0014] The present invention also provides a method for preparing a heat-resistant and high-strength aluminum-based composite brake disc for passenger vehicles. The process is as follows: the composite friction layer is placed on the substrate layer, the position is adjusted, and then the disc is welded by friction stir welding to obtain the final product.
[0015] This invention combines the friction layer and the base layer using friction stir welding technology. During the welding process, the material does not undergo overall melting and deformation, which can effectively avoid defects such as porosity and shrinkage cavities that are easily generated during aluminum alloy fusion welding, thereby improving the overall reliability and toughness of the brake disc.
[0016] As a preferred embodiment, the composite material friction layer and the substrate layer need to be surface cleaned before friction stir welding. The process is as follows: cleaning with caustic soda solution, rinsing with ethanol, and then drying.
[0017] As a preferred embodiment, the preparation process of the composite friction layer is as follows: the reinforcing particle powder is mixed evenly with Al-Fe-V-Si aluminum alloy powder, and then the mixed powder is pressed into a blank by cold isostatic pressing, followed by vacuum hot pressing sintering, and then hot extrusion to obtain the final product.
[0018] As a preferred embodiment, the vacuum hot pressing sintering process is as follows: the blank is placed in a vacuum hot press, the sintering temperature is 500~600℃, and the holding time is 3~5h at 70~80MPa.
[0019] The combination of vacuum hot pressing sintering and hot extrusion can effectively eliminate defects such as pores in composite materials prepared by powder metallurgy, while also improving the interfacial bonding between the aluminum matrix and the reinforcing phase particles and refining the grain size.
[0020] As a preferred embodiment, the conditions for friction stir welding are: stirring speed of 300~1200 r / min, welding speed of 50~150 mm / min, and stirring head tilt angle of 2~4°.
[0021] The friction stir welding method used in this invention generates heat through friction between a high-speed rotating stirring head and the workpiece, causing the material to be welded to soften locally. As the stirring head moves along the welding interface, the already plasticized material flows from the front end to the rear end of the stirring head under the action of the rotational friction force of the stirring head, and forms a dense solid phase weld under the extrusion of the stirring head. During the friction stir process, the original defects near the contact surface between the base layer and the friction layer are destroyed, thereby obtaining a finer and more uniform grain structure.
[0022] Specifically, the present invention also provides a detailed preparation process for heat-resistant, high-strength aluminum-based composite brake discs for passenger vehicles, including the following steps:
[0023] 1) Substrate preparation: ZL101 aluminum alloy is machined and heat-treated to form the required shape;
[0024] 2) Friction layer preparation: The aluminum-based composite material is prepared by powder metallurgy hot extrusion process. 15 wt.%~30 wt.% of reinforcing particle powder is mixed evenly with commercial Al-Fe-V-Si powder. The mixed powder is then cold isostatically pressed into a blank, which is then placed in a vacuum hot press for vacuum hot pressing sintering at a temperature of 580 ℃ and a holding temperature of 75 MPa for 4 h. Subsequently, the composite material ingot is hot extruded to form a sheet.
[0025] 3) Brake disc composite: The friction layer is placed on the base layer. After adjusting the position, the friction layer and the aluminum alloy base layer are fixed. The friction layer and the aluminum alloy base layer are welded together by friction stir welding to form a brake disc.
[0026] Compared with the prior art, the beneficial technical effects of the present invention are as follows:
[0027] 1) The composite material brake disc provided by this invention, based on the synergistic effect between the matrix layer and the friction layer, ensures the specific strength and specific stiffness performance of the brake disc while significantly improving its heat resistance, especially its mechanical properties under high-temperature conditions above 300℃; the friction layer of this brake disc uses Al-Fe-V-Si aluminum alloy as the matrix, utilizing the finely dispersed Al... 12 The (Fe,V)3Si heat-resistant phase is used to achieve high-temperature strengthening, and combined with ceramic reinforcing particles, the strength, modulus, wear resistance, fatigue resistance and thermal expansion of the material are further improved.
[0028] 2) In the preparation method provided by the present invention, the substrate layer and the friction layer are bonded together by friction stirring welding. This process generates heat through the friction between the high-speed rotating stirring head and the workpiece, causing the material to be welded to soften locally. When the stirring head moves along the welding interface, the plasticized material flows from the front end to the rear end of the stirring head under the action of the rotational friction force of the stirring head, and forms a dense solid phase weld under the extrusion of the stirring head. In addition, during the friction stirring process, the original defects near the contact surface between the substrate layer and the friction layer are destroyed, thereby obtaining a finer and more uniform grain structure.
[0029] 3) In the technical solution provided by this invention, the friction layer uses particle-reinforced aluminum-based composite material, and the matrix layer uses aluminum alloy with good strength and toughness. Combining the two materials not only ensures that the brake disc has good overall toughness, but also improves wear resistance and heat resistance, thereby improving the overall mechanical properties of the aluminum-based composite brake disc and enhancing the reliability of the brake disc. Testing shows that the cross-sectional strength R of the brake disc provided by this invention... m With a strength of 160~190 MPa and an elongation at break (A≥1%), its stress strength is around 250 MPa at 300℃ and remains above 100 MPa at 500℃, demonstrating excellent high-temperature performance. Attached Figure Description
[0030] Figure 1 This is a microstructure diagram of the composite friction layer before friction stir lap welding in Embodiment 1 of the present invention;
[0031] Figure 2 This is a microstructure diagram of the composite friction layer after friction stir lap welding in Embodiment 1 of the present invention;
[0032] Figure 3 This is a schematic diagram of the friction layer and the substrate layer in the cross-sectional view of the brake disc in Embodiment 1 of the present invention;
[0033] Figure 4 This is a structural diagram of the brake disc in Embodiment 1 of the present invention;
[0034] Figure 5 This is a stress strength test diagram of the brake disc in Embodiment 1 of the present invention;
[0035] in, Figure 5 (a) is a schematic diagram of the thermal simulation scheme for the composite material layer. Figure 5 (b) is for a strain rate of 0.1 s. -1 The flow stress curve at that time. Figure 5 (c) represents a strain rate of 1 s. -1 The flow stress curve at that time. Figure 5 (d) represents a strain rate of 10 s⁻¹-1 The flow stress curve at that time. Detailed Implementation
[0036] To facilitate understanding of the present invention, a more comprehensive and detailed description of the invention will be provided below in conjunction with the accompanying drawings and preferred embodiments. It should be noted that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0037] Example 1
[0038] This embodiment provides a heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles, and its specific preparation method includes the following steps:
[0039] 1. Substrate layer manufacturing
[0040] Using ZL101 aluminum alloy as raw material, the base layer is prepared by casting, and then machined and heat-treated to form the required shape.
[0041] 2. Preparation of composite material friction layer
[0042] The composite friction layer is prepared via a powder metallurgy hot extrusion process. 15 wt.% SiC powder is uniformly mixed with commercially available Al-Fe-V-Si powder. The mixed powder is then cold isostatically pressed into a billet, which is subsequently placed in a vacuum hot press for vacuum hot pressing sintering at 580℃ and 75 MPa for 4 hours. To eliminate defects such as pores in the composite material prepared by powder metallurgy, and to improve the interfacial bonding between the aluminum matrix and the reinforcing phase particles, and refine the grain size, the composite ingot is then hot extruded to form a sheet. Figure 1 The figure shows the metallographic structure of the material used in the friction layer. As can be seen from the figure, the SiC particles are small and uniformly distributed, with no obvious agglomeration.
[0043] 3. Composite of substrate layer and friction layer
[0044] The cut friction layer is placed on the base layer. After adjusting its position, the friction layer and the aluminum alloy base layer are fixed in place. Friction stir welding is then used to weld the friction layer and the aluminum alloy base layer together to form a brake disc. Figure 2 The diagram shows the structural schematics of the substrate layer and friction layer prepared using the above method. During the friction stir processing, the stirring speed was 400 r / min, the welding speed was 50 mm / min, and the stirring head tilt angle was 2.5°. During the friction stir processing, the original defects near the contact surface between the substrate layer and the friction layer were broken up, resulting in a microstructure with finer and more uniform grain size.
[0045] The interfacial bonding strength R between the brake disc substrate layer and the friction layer prepared in Example 1 was tested. m ≈183 MPa, elongation after fracture A≥1%.
[0046] Example 2
[0047] This embodiment is exactly the same as Embodiment 1, except that the reinforcing particles used in the aluminum-based composite material are TiC particles with a mass fraction of 15 wt.%.
[0048] The interfacial bonding strength R between the brake disc substrate layer and the friction layer prepared in Example 2 was tested. m ≈181 MPa, elongation after fracture A≥1%.
[0049] Example 3
[0050] This embodiment is exactly the same as Embodiment 1, except that the reinforcing particles used in the aluminum-based composite material are 15 wt.% BN particles.
[0051] The interfacial bonding strength R between the brake disc substrate layer and the friction layer prepared in Example 3 was tested. m ≈183 MPa, elongation after fracture A≥1%.
[0052] Example 4
[0053] This embodiment is exactly the same as Embodiment 1, except that the reinforcing particles used in the aluminum-based composite material are 25 wt.% SiC particles.
[0054] The interfacial bonding strength R between the brake disc substrate layer and the friction layer prepared in Example 4 was tested. m ≈190 MPa, elongation after fracture A≥1%.
[0055] Example 5
[0056] This embodiment is exactly the same as Embodiment 1, except that the stirring speed of the friction stir process is 600 r / min and the welding speed is 100 mm / min.
[0057] The interfacial bonding strength R between the brake disc substrate layer and the friction layer prepared in Example 4 was tested. m ≈170 MPa, elongation after fracture A≥1%.
[0058] Example 6
[0059] This embodiment is exactly the same as Embodiment 1, except that the stirring speed of the friction stir process is 800 r / min and the welding speed is 100 mm / min.
[0060] The interfacial bonding strength R between the brake disc substrate layer and the friction layer prepared in Example 4 was tested. m ≈172MPa, elongation after fracture A≥1%.
[0061] To better understand the heat resistance of the brake disc provided by this invention, the stress strength of the brake disc obtained in Example 1 was also tested at different temperatures. The test results are as follows: Figure 5 As shown, through Figure 5 It can be seen that, compared with most aluminum-based composites, SiCp / Al-Fe-V-Si exhibits better high-temperature resistance. When the deformation temperature is 300℃, the flow stress can be maintained at around 220MPa, and when the deformation temperature reaches 500℃, the flow stress can still remain above 100MPa. This is mainly attributed to the presence of a large number of finely dispersed Al atoms in the SiCp / Al-Fe-V-Si matrix. 12 (Fe,V)3Si heat-resistant phase.
[0062] 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 heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles, characterized in that, include: Aluminum alloy substrate layer and composite material friction layer through friction welding; The composite friction layer comprises an Al-Fe-V-Si aluminum alloy and reinforcing particles; the reinforcing particles are at least one of SiC, BN, and TiC. The preparation process of the brake disc is as follows: the composite material friction layer is placed on the substrate layer, the position is adjusted, and then it is welded by friction stir welding to obtain the disc. The preparation process of the composite friction layer is as follows: the reinforcing particle powder is mixed evenly with Al-Fe-V-Si aluminum alloy powder, and then the mixed powder is pressed into a blank by cold isostatic pressing, then vacuum hot pressing sintering, and then hot extrusion to obtain the final product. The conditions for friction stir welding are: stirring speed of 300~1200 r / min, welding speed of 50~150 mm / min, and stirring head tilt angle of 2~4°. The Al-Fe-V-Si aluminum alloy comprises the following components by mass percentage: Fe 8.3~8.5%, Si 1.0~1.9%, V 1.2~1.4%, Zn 0.2~0.3%, Cr 0.1~0.3%, Mn 0.1~0.3%, Ti 0.1~0.3%, with the balance being aluminum.
2. The heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles according to claim 1, characterized in that: The tensile strength Rm of the substrate layer is ≥200 MPa, the elongation after fracture A is ≥9%, and the hardness is ≥65 HV0.2; the aluminum alloy substrate layer is ZL101 aluminum alloy.
3. The heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles according to claim 1, characterized in that: The reinforcing particles account for 15-30% of the total mass of the composite friction layer; the particle size of the reinforcing particles is 5-30 μm, and the distribution pattern is normally distributed.
4. A heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles according to claim 1 or 3, characterized in that: The friction layer has a tensile strength Rm ≥ 380 MPa, elongation after fracture A ≥ 3%, hardness ≥ 140 HV0.2, and density of 2.9~3.0 g / cm³. 3 .
5. The heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles according to claim 1, characterized in that: Before the composite material friction layer and the substrate layer are welded by friction stir welding, the surface needs to be cleaned. The process is as follows: after cleaning with caustic soda solution, rinsed with ethanol, and then dried.
6. The heat-resistant, high-strength aluminum-based composite brake disc for passenger vehicles according to claim 5, characterized in that: The vacuum hot pressing sintering process is as follows: the blank is placed in a vacuum hot press, the sintering temperature is 500~600℃, and the pressure holding time is 3~5h at 70~80MPa.