Aluminum piston material for internal combustion engines and method for producing the same

Abstract

The present application relates to an internal combustion engine aluminum piston material and a preparation method thereof, comprising the following components by weight fraction: 100 parts of a base alloy; 5-25 parts of a composite material; the composite material comprises a skeleton reinforcing phase and a whisker reinforcing phase, and the mass ratio of the skeleton reinforcing phase to the whisker reinforcing phase is (2-8):1; through the cross-scale synergy of the skeleton reinforcing phase and the whisker reinforcing phase, the skeleton reinforcing phase forms a micron-level rigid skeleton to bear macroscopic load, the whisker reinforcing phase fills the skeleton gap to form a sub-micron-level reinforcing network to inhibit micro-crack initiation, the two produce a synergistic effect of "1+1>2", and the performance deterioration caused by insufficient bearing or missing reinforcement under a single reinforcing phase is avoided.

Description

Technical Field

[0001] This invention relates to the field of piston technology, and more particularly to aluminum piston materials for internal combustion engines and their preparation methods. Background Technology

[0002] The piston is one of the core components of a car engine, often referred to as the "heart" of the engine. Its function is to withstand the pressure of combustion gases and, through the piston pin, transmit energy to the connecting rod, thereby driving the crankshaft. Therefore, the piston is a crucial factor determining the overall quality of the engine. Currently, with the continuous improvement of technical specifications such as internal combustion engine power and combustion pressure, the working environment of the piston is becoming increasingly demanding. It simultaneously withstands high-pressure, high-speed, and high-temperature mechanical and thermal loads, which places special requirements on piston materials. Currently, the most common aluminum piston materials are hypereutectic Al-Si alloys, which provide wear resistance and a certain strength support through the precipitation of primary silicon and eutectic silicon phases. However, with the continuous improvement of engine strength, traditional hypereutectic Al-Si alloys have gradually revealed a prominent problem: the contradiction between strength and wear resistance is difficult to reconcile. Although increasing the silicon content can improve wear resistance, it will lead to coarsening of primary silicon, which will increase the brittleness of the material, deteriorate the machinability, and significantly reduce the high-temperature strength, making it difficult to meet the dual requirements of high-strength engines for high-temperature mechanical properties and wear resistance. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides the following technical solution: One aspect provides an aluminum piston material for internal combustion engines, comprising the following components in parts by weight: 100 parts of the base alloy; 5-25 parts of composite material; The composite material includes a skeleton reinforcing phase and a whisker reinforcing phase, wherein the mass ratio of the skeleton reinforcing phase to the whisker reinforcing phase is (2-8):1; The framework reinforcement phase comprises modified SiC and modified graphite, wherein the mass ratio of modified SiC to modified graphite is (3-6):1; The whisker-reinforcing phase comprises SiC whiskers and potassium titanate whiskers, wherein the mass ratio of SiC whiskers to potassium titanate whiskers is (2-5):1.

[0004] As an improvement to the above technical solution, the matrix alloy comprises the following components by mass percentage: Si 11.0%-15.0%, Cu 4.0%-6.0%, Ni 2.5%-4.5%, Mg 0.8%-1.2%, Fe 0.2%-0.5%, Mn 0.1%-0.4%, Zr 0.08%-0.20%, V 0.05%-0.15%, with the balance being Al and unavoidable impurities.

[0005] As an improvement to the above technical solution, in the framework reinforcing phase, the particle size of SiC particles is 5-25μm, the particle size of graphite particles is 10-35μm, and the ratio of the particle size of graphite particles to the particle size of SiC particles is (1.2-2.5):1.

[0006] As an improvement to the above technical solution, the method for preparing the surface-modified SiC particles includes the following steps: S1 pretreatment: SiC particles are sequentially subjected to degreasing, roughening, sensitization and activation treatments to form catalytic active centers on the surface; S2 electroless plating: Pretreated SiC particles are added to Ni-P plating solution and plated for 20-60 minutes at 80-90℃ and pH=4.2-5.0 to deposit a Ni-P alloy layer on the surface of SiC particles. S3 Post-treatment: After plating, filter and wash, then vacuum dry at 80-100℃ for 2-4 hours to obtain SiC particles with a Ni-P coating on the surface.

[0007] As an improvement to the above technical solution, the method for preparing the surface-coated graphite particles includes the following steps: S1 Pretreatment: The graphite particles are sequentially subjected to degreasing and roughening treatments to remove surface impurities and increase surface roughness; S2 Surface Coating: Pretreated graphite particles are added to the coating solution, and Al2O3 is coated on the graphite surface by non-uniform nucleation method. The coating temperature is 50-80℃, pH=5-7, and the reaction time is 30-120 minutes. S3 post-treatment: After coating, filter and wash, dry at 80-120℃, and then calcine at 400-600℃ for 1-3 hours to obtain graphite particles with an Al2O3 coating.

[0008] On the other hand, a method for preparing an aluminum piston material for an internal combustion engine is provided, comprising the following steps: Preparation of S1 composite powder: The skeleton reinforcement phase and the whisker reinforcement phase are mixed according to the formula, and 0.2%-0.5% of polyvinylpyrrolidone (PVP) is added as a dispersant at a shear rate of 8000-15000 s. -1 High-shear dispersion for 20-30 minutes, followed by filtration and vacuum drying at 80-100℃ to obtain composite powder; S2 semi-solid thixotropic molding: The base alloy is heated to 740-770℃ to melt, refined and degassed, and then cooled to the semi-solid range of 600-640℃. The formula amount of composite powder is added, and the mixture is mechanically stirred at 300-500 rpm for 15-30 minutes. The mixed alloy liquid is then heated to 650-680℃ to obtain a mixed alloy liquid for casting.

[0009] In the semi-solid mixing process of S2, 0.2%-0.5% of K2TiF6 by the total mass of the melt is added to the semi-solid slurry.

[0010] The beneficial effects of this invention are: Through the cross-scale synergy of the skeleton reinforcement phase and the whisker reinforcement phase, the skeleton reinforcement phase forms a micron-level rigid skeleton to bear the macroscopic load, while the whisker reinforcement phase fills the gaps in the skeleton to form a submicron-level reinforcing network to suppress the initiation of microcracks. The two produce a synergistic effect of "1+1>2", avoiding the performance degradation caused by insufficient load bearing or lack of reinforcement under a single reinforcement phase. By combining the rigidity and flexibility of modified SiC and modified graphite, modified SiC provides high strength and low thermal expansion, while modified graphite provides self-lubrication and rapid thermal conduction, forming a complementary synergy of "rigidity and flexibility". This avoids the strength reduction caused by excessive graphite or the wear rate increase caused by excessive SiC. At the same time, by coating the SiC surface with a Ni-P alloy layer and the graphite surface with an Al2O3 layer, a chemical bonding interface between the reinforcing phase and the aluminum matrix is ​​established, preventing the formation of brittle phases through interfacial reactions, improving the wettability of graphite and molten aluminum, and ensuring the effective transfer of load. By synergistically combining SiC whiskers and potassium titanate whiskers across the entire temperature range, SiC whiskers improve room temperature fatigue strength through bridging and pull-out effects, while potassium titanate whiskers improve high temperature tensile strength by pinning grain boundaries and inhibiting creep, thus avoiding the problem of decreased high-temperature performance or poor dispersion when a single whisker is used excessively. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0012] Unless otherwise specified, the main components involved in the following embodiments of this application are all purchased from commercially available products.

[0013] To address the inherent contradiction between strength and wear resistance, this invention employs the following technical solution: SiC in the reinforcing skeleton possesses high hardness, high elastic modulus, and a low coefficient of thermal expansion. After modification with a Ni-P coating, its interfacial wettability with the aluminum matrix is ​​significantly improved, preventing the formation of the brittle Al4C3 phase from the reaction of the original SiC with the molten aluminum. During the semi-solid thixotropic forming process, SiC particles, acting as a rigid skeleton, are uniformly distributed within the matrix, bearing the main load and suppressing plastic deformation of the matrix. This improves the tensile strength, yield strength, and creep resistance of the material. Simultaneously, the low thermal expansion of SiC effectively reduces the overall coefficient of thermal expansion of the composite material, allowing the piston to withstand high-temperature conditions. The cylinder liner maintains a stable fit clearance; after the modified graphite particles are modified by coating the surface with an Al2O3 layer, the interfacial bonding strength between graphite and aluminum matrix is ​​significantly improved, achieving a uniform and stable distribution of graphite in the matrix. During the friction and wear process, the graphite particles form a continuous solid lubricating film at the friction interface, reducing the friction coefficient and wear rate. At the same time, the high thermal conductivity of graphite helps to quickly conduct the heat accumulated at the piston top to the piston ring area, reducing the thermal stress at the piston head and improving the thermal fatigue resistance. Fine SiC particles can fill the gaps between coarse graphite particles to form a tightly packed structure, maximizing the volume fraction of the skeleton reinforcement phase and reducing defects and pores in the matrix. In the whisker-reinforced phase, SiC whiskers (high-strength microfibers) are three-dimensionally randomly distributed in the matrix. When the material is subjected to external loads, SiC whiskers bridge the microcracks through a "bridging effect," hindering crack initiation and propagation. Simultaneously, they dissipate fracture energy through a "pull-out effect," thereby improving the material's fracture toughness and fatigue strength. Potassium titanate whiskers (high-temperature resistant microfibers) possess a unique tunnel crystal structure, with a thermal expansion coefficient close to that of the aluminum matrix, exhibiting excellent thermal stability. During high-temperature service, potassium titanate whiskers effectively pin grain boundaries, inhibiting grain growth and creep deformation in the matrix, significantly improving the material's high-temperature tensile strength and thermal fatigue resistance. Furthermore, the interface between potassium titanate whiskers and the aluminum matrix is ​​well-bonded, making interface debonding less likely. The skeleton reinforcement phase acts as the main load-bearing skeleton to bear the macroscopic load, while the whisker reinforcement phase fills the gaps in the skeleton to inhibit the initiation of microcracks, forming an optimal synergistic structure of "macroscopic load bearing - microscopic reinforcement". If there is too little skeleton, the rigidity will be insufficient, and if there are too few whiskers, the fatigue resistance will decrease. Thixotropic properties of solid slurry: In the semi-solid range of 600-640℃, the matrix alloy exhibits a thixotropic state of solid-liquid coexistence. When composite powder is added at this time, the semi-solid slurry has a high apparent viscosity, which can effectively hinder the sedimentation and floating of the reinforcing phase and achieve uniform distribution of the reinforcing phase. The Ti and F elements produced by the decomposition of K2TiF6 in the melt can form a protective film on the surface of the whiskers, preventing the whiskers from being damaged by interfacial reactions with the molten aluminum. At the same time, the Ti element participates in the formation of the Al3Ti phase, further improving the interfacial bonding between the whiskers and the matrix. Example 1

[0014] First, modified SiC and modified graphite (skeletal reinforcing phase component) were prepared. The modified SiC was prepared by sequentially subjecting SiC particles to degreasing, roughening, sensitization, and activation treatments to form catalytic active centers on the surface. The pretreated SiC particles were then added to a Ni-P plating solution and plated at 85℃ and pH=4.6 for 40 minutes to deposit a Ni-P alloy layer on the surface of the SiC particles. After plating, the particles were filtered, washed, and vacuum dried at 90℃ for 3 hours to obtain SiC particles (particle size 10 μm) coated with a Ni-P coating. The modified graphite was prepared as follows: graphite particles were sequentially degreased and roughened to remove surface impurities and increase surface roughness. The pretreated graphite particles were then added to a coating solution, and Al2O3 was coated onto the graphite surface using a non-uniform nucleation method. The coating temperature was 65℃, pH=6, and the reaction time was 75 minutes. After coating, the particles were filtered, washed, dried at 100℃, and then calcined at 500℃ for 2 hours to obtain graphite particles (particle size 18μm) coated with an Al2O3 layer. Composite powder preparation: The modified SiC and modified graphite prepared above were mixed at a mass ratio of 4:1 as the skeleton reinforcement phase, and then mixed with a whisker reinforcement phase composed of SiC whiskers and potassium titanate whiskers at a mass ratio of 3:1 (the mass ratio of the skeleton reinforcement phase to the whisker reinforcement phase is 4:1). Polyvinylpyrrolidone (PVP) accounting for 0.35% of the total powder mass was added as a dispersant, and the mixture was subjected to a shear rate of 11000 s⁻¹. -1 High shear dispersion for 25 minutes, followed by filtration and vacuum drying at 90°C to obtain composite powder; The matrix alloy composition is Si 12.0%, Cu 5.0%, Ni 3.5%, Mg 1.0%, Fe 0.3%, Mn 0.2%, Zr 0.12%, V 0.10%, with the balance being Al and unavoidable impurities. The matrix alloy is heated to 750℃ to melt, refined and degassed, and then cooled to a semi-solid range of 620℃. 15 parts by weight of composite powder are added, along with 0.35% K2TiF6 by weight of the total melt mass. The mixture is mechanically stirred at 400 rpm for 20 minutes, and then the mixed alloy liquid is heated to 650℃ to obtain a mixed alloy liquid for casting. Example 2

[0015] First, modified SiC and modified graphite were prepared. The modified SiC was prepared by sequentially subjecting SiC particles to degreasing, roughening, sensitization, and activation treatments to form catalytic active centers on the surface. The pretreated SiC particles were then added to a Ni-P plating solution and plated at 80°C and pH=4.2 for 20 minutes to deposit a Ni-P alloy layer on the surface of the SiC particles. After plating, the particles were filtered, washed, and vacuum dried at 80°C for 2 hours to obtain SiC particles (5 μm in diameter) coated with a Ni-P coating. The modified graphite was prepared as follows: graphite particles were sequentially degreased and roughened to remove surface impurities and increase surface roughness; the pretreated graphite particles were added to a coating solution, and Al2O3 was coated on the graphite surface by a non-uniform nucleation method at a coating temperature of 50℃, pH=5, and a reaction time of 30 minutes; after coating, the particles were filtered, washed, dried at 80℃, and then calcined at 400℃ for 1 hour to obtain graphite particles (6μm in diameter) with an Al2O3 coating layer on the surface. Composite powder preparation: The modified SiC and modified graphite prepared above were mixed at a mass ratio of 3:1 as the skeleton reinforcement phase, and then mixed with a whisker reinforcement phase composed of SiC whiskers and potassium titanate whiskers at a mass ratio of 2:1 (the mass ratio of the skeleton reinforcement phase to the whisker reinforcement phase is 2:1). Polyvinylpyrrolidone (PVP) accounting for 0.2% of the total powder mass was added as a dispersant, and the mixture was subjected to a shear rate of 8000 s⁻¹. -1 The composite powder was obtained by high shear dispersion for 20 minutes, filtration, and vacuum drying at 80°C. The matrix alloy composition is Si 11.0%, Cu 4.0%, Ni 2.5%, Mg 0.8%, Fe 0.2%, Mn 0.1%, Zr 0.08%, V 0.05%, with the balance being Al and unavoidable impurities. The matrix alloy is heated to 740℃ to melt, refined and degassed, and then cooled to a semi-solid range of 600℃. Five parts by weight of composite powder are added, along with 0.20% by weight of K2TiF6 of the total melt mass. The mixture is mechanically stirred at 300 rpm for 15 minutes, and then heated to 670℃ to obtain a mixed alloy liquid for casting. Example 3

[0016] First, modified SiC and modified graphite were prepared. The modified SiC was prepared by sequentially subjecting SiC particles to degreasing, roughening, sensitization, and activation treatments to form catalytic active centers on the surface. The pretreated SiC particles were then added to a Ni-P plating solution and plated at 90°C and pH=5.0 for 60 minutes to deposit a Ni-P alloy layer on the surface of the SiC particles. After plating, the particles were filtered, washed, and vacuum dried at 100°C for 4 hours to obtain SiC particles (particle size 25 μm) coated with a Ni-P coating. The modified graphite was prepared as follows: graphite particles were sequentially degreased and roughened to remove surface impurities and increase surface roughness; the pretreated graphite particles were added to a coating solution, and Al2O3 was coated on the graphite surface by a non-uniform nucleation method at a coating temperature of 80℃, pH=7, and a reaction time of 120 minutes; after coating, the particles were filtered, washed, dried at 120℃, and then calcined at 600℃ for 3 hours to obtain graphite particles (50 μm in diameter) with an Al2O3 coating layer on the surface. Composite powder preparation: The modified SiC and modified graphite prepared above were mixed at a mass ratio of 6:1 as the skeleton reinforcement phase, and then mixed with a whisker reinforcement phase composed of SiC whiskers and potassium titanate whiskers at a mass ratio of 5:1 (the mass ratio of the skeleton reinforcement phase to the whisker reinforcement phase is 8:1). Polyvinylpyrrolidone (PVP) accounting for 0.5% of the total powder mass was added as a dispersant, and the mixture was subjected to a shear rate of 15000 s. -1 The composite powder was obtained by high shear dispersion for 30 minutes, filtration, and vacuum drying at 100°C. The matrix alloy composition is Si 15.0%, Cu 6.0%, Ni 4.5%, Mg 1.2%, Fe 0.5%, Mn 0.4%, Zr 0.20%, V 0.15%, with the balance being Al and unavoidable impurities. The matrix alloy is heated to 770℃ to melt, refined and degassed, and then cooled to a semi-solid range of 640℃. 25 parts by weight of composite powder are added, along with 0.50% K2TiF6 by weight of the total melt mass. The mixture is mechanically stirred at 500 rpm for 30 minutes, and then the mixed alloy liquid is heated to 680℃ to obtain a mixed alloy liquid for casting. Comparative Example 1 The difference from Example 1 is that the ratio of the skeleton-reinforcing phase to the whisker-reinforcing phase is 1:1, while other conditions are the same as in Example 1; Comparative Example 2 The difference from Example 1 is that the ratio of the skeleton-reinforcing phase to the whisker-reinforcing phase is 10:1, while other conditions are the same as in Example 1; Comparative Example 3 The difference from Example 1 is that the composite material has only a skeleton reinforcement phase, while the other conditions are the same as in Example 1; Comparative Example 4 The difference from Example 1 is that the composite material has only a whisker-reinforcing phase, while the other conditions are the same as in Example 1; Comparative Example 5 The difference from Example 1 is that the ratio of modified SiC to modified graphite in the framework reinforcing phase is 1:1, while other conditions are the same as in Example 1. Comparative Example 6 The difference from Example 1 is that the ratio of modified SiC to modified graphite in the framework reinforcing phase is 8:1, while other conditions are the same as in Example 1. Comparative Example 7 The difference from Example 1 is that there is no modified graphite in the skeleton reinforcing phase, while the other conditions are the same as in Example 1; Comparative Example 8 The difference from Example 1 is that no modified SiC is present in the framework reinforcement phase, while other conditions are the same as in Example 1; Comparative Example 9 The difference from Example 1 is that the SiC and graphite in the skeleton reinforcement phase are not modified, while other conditions are the same as in Example 1; Comparative Example 10 The difference from Example 1 is that the ratio of SiC whiskers to potassium titanate whiskers in the whisker-reinforced phase is 1:1, while other conditions are the same as in Example 1. Comparative Example 11 The difference from Example 1 is that the ratio of SiC whiskers to potassium titanate whiskers in the whisker-reinforced phase is 6:1, while other conditions are the same as in Example 1. Performance testing The room temperature tensile strength was tested according to GB / T228.1-2010 "Metallic Materials - Tensile Testing Method"; the high temperature tensile strength was tested according to GB / T228.2-2015 "Metallic Materials - High Temperature Tensile Testing Method"; the bending fatigue strength was tested according to GB / T4337-2015 "Metallic Materials - Fatigue Testing - Rotational Bending Method"; the thermal conductivity coefficient was tested according to GB / T22588-2008 "Measuring Thermal Diffusion Coefficient or Thermal Conductivity by Flash Method"; the coefficient of thermal expansion was tested according to GB / T4339-2008 "Determination of Characteristic Parameters of Thermal Expansion of Metallic Materials"; and the relative wear rate was tested according to GB / T12444-2006 "Metallic Materials - Wear Testing Method". The pistons prepared in Example 13 and Comparative Example 111 were subjected to performance tests, and the results are shown in Tables 1 and 2. Table 1 Table 2 As shown in Tables 1 and 2, the tensile strength at 20℃ of Examples 1-3 reached over 375 MPa, and the tensile strength at 300℃ reached over 127 MPa, with a relative wear rate of only 1.0-1.2. In contrast, the tensile strength at 20℃ of Comparative Example 3 (only the framework reinforcement phase) was only 278 MPa, with a relative wear rate as high as 3.6, and the tensile strength at 20℃ of Comparative Example 4 (only the whisker reinforcement phase) was only 295 MPa, with a relative wear rate as high as 2.6. This indicates that through the cross-scale synergy of the framework reinforcement phase and the whisker reinforcement phase, an effective structure can be constructed. A dual-scale network of "macro load-bearing and micro reinforcement" was constructed: the skeleton reinforcement phase (modified SiC / graphite) forms a micron-scale rigid skeleton to bear the macro load, while the whisker reinforcement phase (SiC whiskers / potassium titanate whiskers) fills the gaps in the skeleton to form a submicron-scale reinforcement network to inhibit the initiation of microcracks. The two are uniformly dispersed in the matrix through a semi-solid process, resulting in a synergistic effect of "1+1>2". This avoids local failures caused by insufficient load-bearing or lack of reinforcement under a single reinforcement phase, thereby significantly improving the overall mechanical properties and wear resistance of the piston material.

[0017] The tensile strength and relative wear rate at 20℃ of Example 1 were significantly better than those of Comparative Examples 7 and 8. This indicates that the "rigid-flexible" synergy of modified SiC and modified graphite effectively achieves the complementary functions of rigid support and self-lubricating thermal conductivity: modified SiC, as a hard skeleton, provides high strength and low thermal expansion, while modified graphite, as a lubricating phase, reduces the coefficient of friction and improves thermal conductivity. When the two are compounded in a ratio of (3-6):1, the defects of insufficient strength (excessive graphite) or increased wear rate (excessive SiC) under single components are avoided, thereby significantly improving the comprehensive performance of piston material in terms of strength, wear resistance and thermal conductivity.

[0018] The tensile strength at 300℃ and fatigue strength at 20℃ of Example 1 are significantly better than those of Comparative Examples 10 and 11. This indicates that the "full-temperature range" synergy of SiC whiskers and potassium titanate whiskers effectively achieves the unity of room temperature fatigue and high temperature stability: SiC whiskers improve room temperature fatigue strength through bridging and pull-out effects, while potassium titanate whiskers improve high temperature tensile strength by pinning grain boundaries and inhibiting creep. When the two are compounded in a ratio of (2-5):1, the defects of high temperature performance degradation (excess potassium titanate) or poor dispersibility (excess SiC whiskers) under excessive single whisker are avoided, thereby significantly extending the service life of piston materials under all temperature conditions.

[0019] The tensile strength at 20℃ in Example 1 was significantly better than that in Comparative Example 9. This indicates that the synergistic interface modification of Ni-P coating and Al2O3 coating effectively established a chemical bonding interface between the reinforcing phase and the aluminum matrix. The Ni-P coating prevents SiC from reacting with the aluminum liquid to form the brittle phase Al4C3, while the Al2O3 coating improves the wettability of graphite with the aluminum liquid. Together, they effectively transferred the load from the matrix to the reinforcing phase, avoiding the debonding failure of the physically adsorbed interface during the stress process, thereby significantly improving the interfacial bonding strength and overall mechanical properties of the piston material.

[0020] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. An aluminum piston material for internal combustion engines, characterized in that, Includes the following components by weight: 100 parts of the base alloy; 5-25 parts of composite material; The composite material includes a skeleton reinforcing phase and a whisker reinforcing phase, wherein the mass ratio of the skeleton reinforcing phase to the whisker reinforcing phase is (2-8):1; The framework reinforcement phase comprises modified SiC and modified graphite, wherein the mass ratio of modified SiC to modified graphite is (3-6):1; The whisker-reinforcing phase comprises SiC whiskers and potassium titanate whiskers, wherein the mass ratio of SiC whiskers to potassium titanate whiskers is (2-5):

1.

2. The aluminum piston material for internal combustion engines according to claim 1, characterized in that: The matrix alloy comprises the following components by mass percentage: Si 11.0%-15.0%, Cu 4.0%-6.0%, Ni 2.5%-4.5%, Mg 0.8%-1.2%, Fe 0.2%-0.5%, Mn 0.1%-0.4%, Zr 0.08%-0.20%, V 0.05%-0.15%, with the balance being Al and unavoidable impurities.

3. The aluminum piston material for internal combustion engines according to claim 1, characterized in that: In the framework reinforcement phase, the particle size of SiC particles is 5-25 μm, the particle size of graphite particles is 10-35 μm, and the particle size ratio of graphite particles to SiC particles is (1.2-2.5):

1.

4. The aluminum piston material for internal combustion engines according to claim 2, characterized in that: The method for preparing the surface-modified SiC particles includes the following steps: S1 pretreatment: SiC particles are sequentially subjected to degreasing, roughening, sensitization and activation treatments to form catalytic active centers on the surface; S2 electroless plating: Pretreated SiC particles are added to Ni-P plating solution and plated for 20-60 minutes at 80-90℃ and pH=4.2-5.0 to deposit a Ni-P alloy layer on the surface of SiC particles. S3 Post-treatment: After plating, filter and wash, then vacuum dry at 80-100℃ for 2-4 hours to obtain SiC particles with a Ni-P coating on the surface.

5. The aluminum piston material for internal combustion engines according to claim 2, characterized in that: The method for preparing the surface-coated graphite particles includes the following steps: S1 Pretreatment: The graphite particles are sequentially subjected to degreasing and roughening treatments to remove surface impurities and increase surface roughness; S2 Surface Coating: Pretreated graphite particles are added to the coating solution, and Al2O3 is coated on the graphite surface by non-uniform nucleation method. The coating temperature is 50-80℃, pH=5-7, and the reaction time is 30-120 minutes. S3 post-treatment: After coating, filter and wash, dry at 80-120℃, and then calcine at 400-600℃ for 1-3 hours to obtain graphite particles with an Al2O3 coating.

6. A method for preparing an aluminum piston material for an internal combustion engine as described in any one of claims 1-5, characterized in that: Includes the following steps: Preparation of S1 composite powder: The skeleton reinforcement phase and the whisker reinforcement phase are mixed according to the formula, and 0.2%-0.5% of polyvinylpyrrolidone (PVP) is added as a dispersant at a shear rate of 8000-15000 s. -1 High-shear dispersion for 20-30 minutes, followed by filtration and vacuum drying at 80-100℃ to obtain composite powder; S2 semi-solid thixotropic molding: The base alloy is heated to 740-770℃ to melt, refined and degassed, and then cooled to the semi-solid range of 600-640℃. The formula amount of composite powder is added, and the mixture is mechanically stirred at 300-500 rpm for 15-30 minutes. The mixed alloy liquid is then heated to 650-680℃ to obtain a mixed alloy liquid for casting.

7. In the method for preparing aluminum piston material for internal combustion engines according to claim 6, during the semi-solid mixing process of S2, 0.2%-0.5% of K2TiF6 by mass of the total melt is added to the semi-solid slurry.

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