Ceramic-reinforced aluminum-based composite material and preparation method therefor

Abstract

The present invention belongs to the technical field of aluminum-based composite materials. Disclosed are a ceramic-reinforced aluminum-based composite material and a preparation method therefor. The preparation method comprises: S1, adding silicon carbide grinding balls and a second solvent to aluminum powder (1-10 μm), graded silicon carbide particles, chromite and iron pyrite, and performing first-stage ball milling and material mixing, wherein the silicon carbide particles consist of first silicon carbide particles (10-12 μm) and second silicon carbide particles (25-30 μm) at a volume ratio of (3-4):(6-7) and account for 55-60% of the total volume of the silicon carbide particles and the aluminum powder; S2, adding polyvinylpyrrolidone, and performing second-stage ball milling and material mixing; S3, drying same after the material mixing; and S4, performing hot-pressed sintering, wherein the sintering temperature is 560-580°C, the pressure is 20-40 MPa, and the holding time is 10-15 min. In the present invention, by designing the particle sizes and ratio of the raw materials, optimizing process steps, etc., a ceramic-reinforced aluminum-based composite material which has good compactness, high strength, a high heat conductivity and a small expansion coefficient is eventually obtained.

Description

A ceramic reinforced aluminum-based composite material and preparation method thereof Technical Field

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

[0002] Ceramic particle-reinforced aluminum-based composites (CP-ACMs), as lightweight, high-strength, and multifunctional composites, boast excellent physical and chemical properties, including low density, high specific strength and stiffness, high wear resistance, low thermal expansion coefficient, high thermal conductivity, and good corrosion resistance. They are promising structural materials and have seen rapid development in recent years. Composites prepared using different formulations, composition, preparation processes, and heat treatments exhibit diverse properties, meeting the requirements of applications in fields such as space engineering materials and electronic packaging.

[0003] The most crucial step in the preparation of ceramic particle-reinforced metal matrix composites is how to evenly or precisely distribute the reinforcing particles into the matrix metal, while also controlling parameters such as the particle volume fraction to achieve the desired target material. Currently, common methods for preparing particle-reinforced aluminum matrix composites include stir casting, liquid metal infiltration, spray deposition, and powder metallurgy.

[0004] The stirring casting method achieves the purpose of adding reinforcing particles by adding and stirring the metal in a liquid or molten state. This method makes it difficult to achieve uniform distribution of particles, which affects the performance of the prepared material. The infiltration casting method first shapes the particles as needed to prepare a framework of reinforcing particles. Then, the liquid metal matrix is ​​allowed to infiltrate into the gaps in the framework of the reinforcing particles under suction, pressure, or a combination of the two to fill the gaps and achieve the purpose of mixing. This method is prone to gaps such as pores, which affect the performance of the material. In the spray deposition method, the metal matrix is ​​in an atomized state during mixing. The metal matrix material is first heated to enter a liquid state, then further atomized and mixed with the reinforcing particles. Finally, a composite material is obtained through deposition. The prepared material is not dense enough and requires subsequent processing such as extrusion to improve performance. In addition, the cost of processes such as atomization is relatively high. The powder metallurgy hot pressing sintering method is to mix the reinforcing particles and the metal as the matrix in a powder state, and then hot press and mold them. Its advantage is that the volume fraction of the reinforcing phase can be adjusted arbitrarily and its composition ratio can be controlled more accurately. Mixing in a powder state makes the distribution of the reinforcing particles more uniform, and the performance of the material is better than other preparation processes.

[0005] Many existing ceramic particle-reinforced aluminum-based composites contain numerous additives, and the preparation process is complex and costly. For example, the invention application "CN113957281A: A High-Pressure Preparation Process for Macro-Quantitative Medium- and High-Volume Aluminum-Based Composites" discloses: "Ceramic powder and aluminum matrix powder are mixed; the mixed powder is placed in a metal sheath for cold pressing, and then sealed and welded to an exhaust pipe; the metal sheath is placed in a steel mold, heated in a resistance furnace, and then the exhaust pipe is evacuated using a vacuum pump, and finally sealed and welded to the exhaust pipe; after heating and insulating the steel mold, the mold is moved to a press, tightened on all sides, and then subjected to bidirectional pressurization and lamination; after the mold cools, the billet is removed and the sheath is removed to obtain a macro-quantitative medium- and high-volume aluminum-based composite material." This production process is very complex, has a long production cycle, and is not suitable for large-scale industrial production.

[0006] Therefore, it is now necessary to develop ceramic particle reinforced aluminum-based composite materials and their preparation methods suitable for large-scale industrial production, to obtain a composite material with moderate strength, good thermal conductivity, low thermal expansion coefficient, high temperature resistance and wear resistance and other balanced performance, which can be used in technical fields with high requirements on strength and heat transfer performance and low requirements on thermal deformation.

[0007] Summary of the Invention

[0008] The problem to be solved by the present invention is to provide a ceramic reinforced aluminum-based composite material and a preparation method thereof. By designing the particle size and ratio of raw materials, optimizing the process steps, etc., a ceramic reinforced aluminum-based composite material with good density, high strength, high thermal conductivity and small expansion coefficient suitable for industrial production is finally obtained.

[0009] The present invention includes a method for preparing a ceramic reinforced aluminum matrix composite material, comprising the following steps:

[0010] S1, adding silicon carbide grinding balls and a second solvent to aluminum powder, silicon carbide particles, chromite and pyrite to perform the first stage of ball milling mixing;

[0011] The silicon carbide particles are composed of first silicon carbide particles and second silicon carbide particles in a volume ratio of (3-4):(6-7), the particle size of the first silicon carbide particles is 10-12 μm, and the particle size of the second silicon carbide particles is 25-30 μm;

[0012] The volume of the silicon carbide particles accounts for 55% to 60% of the total volume of the silicon carbide particles and the aluminum powder, and the particle size of the aluminum powder is 1 to 10 μm;

[0013] S2, adding polyvinyl pyrrolidone to the mixture ball-milled in S1 to carry out the second stage of ball-milling;

[0014] S3, mixing the mixture obtained in S2 and drying it;

[0015] S4. Hot pressing and sintering the mixed material obtained in S3 at a sintering temperature of 560-580° C., a pressure of 20-40 MPa, and a holding time of 10-15 minutes.

[0016] Furthermore, it also includes:

[0017] S0, ultrasonically cleaning the silicon carbide particles in a first solvent, and drying them after washing;

[0018] The first solvent includes alcohol or deionized water. The number of ultrasonic cleaning is 1 to 2 times, and the cleaning time for each time is 1 to 30 minutes. The drying temperature after washing is 80 to 120° C., and the drying time is 4 to 6 hours.

[0019] Furthermore, in S1, the mass of the chromite is 0.5% to 1% of the total mass of the silicon carbide particles and the aluminum powder, and the particle size is 15 to 25 μm.

[0020] Furthermore, in S1, the mass of the pyrite is 1% to 2% of the total mass of the silicon carbide particles and the aluminum powder, and the particle size is 15 to 25 μm.

[0021] Furthermore, in S1, the second solvent includes alcohol, the mass ratio of the raw material to the second solvent is 2:1, and the mass ratio of the raw material to the silicon carbide grinding balls is 1:2.

[0022] Furthermore, in S1, the silicon carbide grinding balls include first-size grinding balls and second-size grinding balls in a mass ratio of 1:1, the first-size grinding balls have a particle size of 2-3 mm, and the second-size grinding balls have a particle size of 8-9 mm.

[0023] Furthermore, in S2, the mass of polyvinyl pyrrolidone is 0.3% to 1% of the total mass of the silicon carbide particles and the aluminum powder.

[0024] Furthermore, in S1, the rotation speed of the ball milling in the first stage is 220-300 r / min, and the time is 1-1.5 h; in S2, the rotation speed of the ball milling mixing in the second stage is 300-350 r / min, and the time is 1-1.5 h.

[0025] Furthermore, in S3, the temperature of the drying after mixing is 70 to 120° C. and the time is 8 to 10 hours.

[0026] The present invention also provides a ceramic reinforced aluminum-based composite material, which is obtained by any of the above methods for preparing the ceramic reinforced aluminum-based composite material.

[0027] Beneficial effects of the present invention:

[0028] 1. The volume fraction of silicon carbide (SiC) particles added in the present invention is between 55% and 60%, resulting in a ceramic-reinforced aluminum-based composite material with a high ceramic volume fraction. Metallic aluminum has good thermal conductivity but a large thermal expansion coefficient. In the present invention, adding silicon carbide particles to the aluminum matrix and controlling the ceramic volume fraction to between 55% and 60% ensures that the resulting ceramic-reinforced aluminum-based composite material has a high ceramic volume fraction, good thermal conductivity, and a low thermal expansion coefficient.

[0029] 2. The present invention reduces the thermal expansion coefficient of the composite material and improves its thermal conductivity by adding two silicon carbide particles of different particle sizes. Aluminum powder (particle size 5-10 μm) is smaller than silicon carbide particles. The aluminum powder particles surround the silicon carbide particles and fill the gaps between the two silicon carbide particles. This not only improves the thermal conductivity of the composite material, but also melts during sintering, better bonding the two silicon carbide particles together. The particle size and proportion of the two silicon carbide particles ensure balanced performance of the composite material and better strengthen the aluminum matrix. The small-sized silicon carbide particles fill the pores of the large-sized silicon carbide particles, effectively improving the density of the composite material. The denser the composite material, the lower the thermal expansion coefficient.

[0030] 3. The present invention adds polyvinyl pyrrolidone as a dispersant for wet mixing, effectively promoting uniform mixing of aluminum powder and silicon carbide powder during ball milling. The raw materials of the present invention include chromite and pyrite. Chromite is an iron-chromium oxide with the molecular formula of FeCr2O4. By adding chromite, the wear resistance and strength of the composite material can be improved, and the thermal conductivity of the composite material can also be effectively improved. The main component of pyrite is ferrous disulfide with the molecular formula of FeS2. Sulfide can increase the surface activity of aluminum and ceramic particles during hot pressing and sintering, promote mutual bonding between solid particles, significantly shorten the sintering time, and reduce energy consumption.

[0031] 4. The present invention utilizes hot-pressing sintering to arbitrarily adjust the volume fraction of the reinforcement phase, enabling relatively precise control of its composition ratio. The particle size of the reinforcement phase can be adjusted from nanometers to micrometers. Furthermore, hot-pressing sintering uses lower temperatures and shorter sintering times than pressureless sintering, resulting in a composite material with fewer pores and gaps, and a higher degree of bonding between the reinforcement particles and the matrix.

[0032] 5. The present invention adopts powder metallurgy technology, which is simple in overall process. The composite material has fewer pores and gaps, and the bonding degree between the reinforcing particles and the matrix is ​​higher. By designing the particle size and ratio of the raw materials, optimizing the process steps and parameters, etc., while reducing the thermal expansion coefficient, a more uniform mixing of the raw materials is achieved, and the interface bonding between the reinforcing phase and the matrix is ​​improved. The final result is a ceramic reinforced aluminum-based composite material with good density, high strength, high thermal conductivity and low expansion coefficient. The ceramic reinforced aluminum-based composite material prepared by the present invention has high strength (380-390MPa), high thermal conductivity (230-240W / (mk)), and a low expansion coefficient ((12-14)×10 -6 K) and can be applied to electronic packaging materials or electronic component heat conduction plates. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a process flow chart for preparing a ceramic reinforced aluminum matrix composite material according to one embodiment of the present invention;

[0034] FIG2 is a physical picture of a sample of the ceramic reinforced aluminum-based composite material in Example 1 of the present invention;

[0035] FIG3 is a physical picture of a sample of the ceramic reinforced aluminum-based composite material in Example 5 of the present invention;

[0036] FIG4 is a physical picture of a sample of the ceramic reinforced aluminum-based composite material in Comparative Example 6 of the present invention;

[0037] FIG5 is an electron microscope photograph of a sample of the ceramic reinforced aluminum matrix composite material in Example 5 of the present invention;

[0038] FIG6 is an electron microscope photograph of a sample of the ceramic reinforced aluminum-based composite material in Comparative Example 9 of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0040] As shown in FIG1 , an embodiment of the present invention provides a method for preparing a ceramic reinforced aluminum-based composite material, comprising the following steps:

[0041] S1, adding silicon carbide grinding balls and a second solvent to aluminum powder, silicon carbide particles, chromite and pyrite to perform the first stage of ball milling mixing;

[0042] The silicon carbide particles are composed of first silicon carbide particles and second silicon carbide particles in a volume ratio of (3-4):(6-7), the particle size of the first silicon carbide particles is 10-12 μm, and the particle size of the second silicon carbide particles is 25-30 μm; by adding two silicon carbide particles of different particle sizes, the thermal expansion coefficient is reduced and the thermal conductivity is improved: aluminum powder (particle size 5-10 μm) is smaller than the silicon carbide particles, and the aluminum powder particles surround the silicon carbide particles and fill the gaps between the two silicon carbide particles. On the one hand, it can improve the thermal conductivity, and on the other hand, the aluminum will melt during sintering, which can better bond the silicon carbide particles of the two particle sizes together; the particle size and proportion of the two silicon carbide particles ensure the balanced performance of the composite material, which can better play the role of strengthening the aluminum matrix; the small-sized silicon carbide fills the pores of the large-sized silicon carbide particles, effectively improving the density. The denser the composite material, the smaller the thermal expansion coefficient;

[0043] The volume of the silicon carbide particles accounts for 55% to 60% of the total volume of the silicon carbide particles and aluminum powder (the mass ratio of silicon carbide particles to aluminum powder divided by the density of each = the volume ratio), and the particle size of the aluminum powder is 1 to 10 μm. The volume fraction of the added silicon carbide particles is 55% to 60%, and the resulting ceramic-reinforced aluminum-based composite material has a high ceramic volume fraction. Mixing in a powder state makes the distribution of the silicon carbide-reinforced particles more uniform, and the material's performance is better than other preparation processes. Chromite is an iron-chromium oxide with the molecular formula FeCr2O4, which may contain some magnesium and aluminum, and can improve wear resistance, strength, and thermal conductivity. Pyrite is mainly ferrous disulfide with the molecular formula FeS2, which can shorten sintering time and reduce energy consumption.

[0044] S2, adding polyvinyl pyrrolidone (model K30) to the mixture ball-milled in S1 to carry out the second stage of ball-milling;

[0045] The two-stage ball milling process enhances the uniformity of particle distribution and the interfacial bonding between the particles and the aluminum matrix, thereby improving the performance of the composite material. In the second stage of ball milling, polyvinyl pyrrolidone acts as a dispersant for wet mixing, promoting uniform mixing of aluminum powder and silicon carbide particles during ball milling. It will completely decompose during hot pressing and sintering, without affecting the performance of the composite material.

[0046] S3, mixing the mixture obtained in S2 and drying it;

[0047] S4, hot pressing and sintering the mixture obtained in S3, with a sintering temperature of 560-580°C, a pressure of 20-40 MPa, and a holding time of 10-15 min;

[0048] Hot pressing sintering can arbitrarily adjust the volume fraction of the reinforcing phase, and its composition ratio can be controlled relatively accurately. The particle size of the reinforcing phase can be adjusted in the range of nanometers to micrometers. In addition, the hot pressing sintering method has a lower sintering temperature and a shorter sintering time than normal pressure sintering. The resulting composite material has fewer pores and gaps, and the bonding between the reinforcing particles and the matrix is ​​higher.

[0049] The embodiment of the present invention adopts a powder metallurgy process, which has a simple overall process, fewer pores and gaps in the composite material, and a higher degree of bonding between the reinforcing particles and the matrix. By designing the raw material particle size and ratio, adding ball milling pretreatment to the silicon carbide particles, optimizing the ball milling wet mixing process, etc., while reducing the thermal expansion coefficient, more uniform mixing of the raw materials is achieved, and the interface bonding between the reinforcing phase and the matrix is ​​improved. The final result is a ceramic reinforced aluminum-based composite material with good density, high strength, high thermal conductivity, and low expansion coefficient.

[0050] In a preferred embodiment, it also includes:

[0051] S0. Ultrasonic cleaning of silicon carbide particles in a first solvent, followed by drying after washing; wherein the first solvent includes alcohol or deionized water, the number of ultrasonic cleanings is 1 to 2 times, and each cleaning time is 1 to 30 minutes; the drying temperature after washing is 80 to 120° C., and the drying time is 4 to 6 hours.

[0052] The present invention has discovered through preliminary experiments that the fine adsorbents on the surface of silicon carbide particles are very easy to adsorb gas molecules. When a certain amount of adsorbents exist on the surface of silicon carbide particles, the small-sized adsorbent particles have a strong gas adsorption capacity. The existence of local gas adsorption will reduce the wettability of the particles at that location with the molten aluminum liquid, causing gas entrapment during the infiltration process, thereby reducing the wettability between the ceramic particles and the molten aluminum liquid, resulting in the ceramic particles not being evenly dispersed in the molten aluminum liquid. The present invention ultrasonically cleans the silicon carbide particles before ball milling. Because the adsorbents and silicon carbide particles are physically adsorbed, their binding force is a weak intermolecular force. Therefore, the fine particles can be smoothly desorbed through the cavitation effect and the impact generated by the acoustic flow during the ultrasonic process, thereby achieving the purpose of cleaning the surface. Through experimental comparison, it was found that under the same formula and hot pressing process conditions, the relative density of the sample prepared using cleaned silicon carbide particles was nearly 1% higher than that of the solution using uncleaned silicon carbide particles.

[0053] In S1, the mass of the chromite is 0.5% to 1% of the total mass of the silicon carbide particles and the aluminum powder, and the particle size is 15 to 25 μm.

[0054] In S1, the mass of the pyrite is 1% to 2% of the total mass of the silicon carbide particles and the aluminum powder, and the particle size is 15 to 25 μm.

[0055] In S1, the second solvent includes alcohol, the mass ratio of the raw material to the second solvent is 2:1, and the mass ratio of the raw material to the silicon carbide grinding balls is 1:2.

[0056] In S1, the silicon carbide grinding balls include grinding balls of a first particle size and grinding balls of a second particle size in a mass ratio of 1:1. The first particle size is 2-3 mm, and the second particle size is 8-9 mm. The uniformity of the reinforcing particles' distribution and the interfacial bonding between the reinforcing particles and the aluminum matrix are two key issues affecting the composite material's performance. In preliminary ball milling experiments, the present invention found that using a single-sized grinding ball for milling yields a wider range of SiC particle size distributions at the same time and speed. Compared with using the same milling media, using a combination of large and small milling media achieves higher milling efficiency and allows for more uniform mixing of various raw material particles. When using two sizes of milling media for milling, the large-sized milling media first disperses the powder, while the small-sized milling media simultaneously applies high-frequency extrusion and collision to the slightly agglomerated powder. The combination of the two sizes of milling media efficiently converts gravitational potential energy into the milled powder, improving mixing efficiency and dispersion uniformity in a short period of time, thereby ensuring uniform dispersion of the ceramic particles within the aluminum powder. The present invention uses silicon carbide grinding balls of two sizes (particle diameters) for high-energy ball milling mixing, which can effectively change the morphology of silicon carbide particles and control the particle size of silicon carbide particles. During the ball milling process, the silicon carbide particles are continuously squeezed into the gaps between the aluminum matrix particles under the collision, extrusion, shearing and other effects of the grinding balls, and the silicon carbide particles are evenly dispersed in the aluminum matrix, thereby forming and improving the interface bonding between the silicon carbide particles and the aluminum matrix.

[0057] Wherein, in S2, the mass of polyvinyl pyrrolidone is 0.3% to 1% of the total mass of silicon carbide particles and aluminum powder.

[0058] Among them, in S1, the rotation speed of the ball milling in the first stage is 220-300 r / min, and the time is 1-1.5 h; in S2, the rotation speed of the ball milling mixing in the second stage is 300-350 r / min, and the time is 1-1.5 h.

[0059] In S3, the temperature of the drying after mixing is 70 to 120° C., and the time is 8 to 10 hours.

[0060] The ceramic reinforced aluminum matrix composite material obtained by the above preparation method has high strength (380-390 MPa), high thermal conductivity (230-240 W / (mk)), low expansion coefficient ((12-14)×10 -6 K) and can be applied to electronic packaging materials or electronic component heat conduction plates.

[0061] Example 1

[0062] This embodiment provides a method for preparing a ceramic reinforced aluminum-based composite material, comprising the following steps:

[0063] S1. Place 5-10 μm aluminum powder, SiC particles (the volume of which is 55% of the total volume of the aluminum powder and silicon carbide particles, including two sizes of SiC particles, 10-12 μm and 25-30 μm, with a volume ratio (i.e., mass ratio) of 3.5:6.5), 15-25 μm chromite (the mass of which is 0.5% of the total mass of the aluminum powder and silicon carbide particles), and 15-25 μm pyrite (the mass of which is 1% of the total mass of the aluminum powder and silicon carbide particles), together with SiC grinding balls in a ball mill, add alcohol, and use SiC grinding balls (the mass ratio of 2-3 mm grinding balls to 8-9 mm grinding balls is 1:1). The mass ratio of the total powder to the grinding balls is 1:2; the mass ratio of the total powder to the alcohol is 2:1. The ball mill speed is 220-300 r / min, and the ball milling time is 1-1.5 h.

[0064] S2. Add polyvinyl pyrrolidone powder at a mass of 0.3% of the total mass of aluminum powder and silicon carbide powder, rotate at 300-350 r / min, and continue ball milling for 1-1.5 hours;

[0065] S3, after the ball milling is completed, the mixture is dried at a temperature of 70-100°C for 10 hours;

[0066] S4. The mixed and dried powder is placed in a mold for hot pressing and sintering at a temperature of 580°C, a pressure of 20 MPa, and a holding time of 10 minutes.

[0067] Example 2

[0068] This embodiment provides a method for preparing a ceramic reinforced aluminum-based composite material, comprising the following steps:

[0069] S1. Place 5-10 μm aluminum powder, SiC particles (the volume of which is 55% of the total volume of the aluminum powder and silicon carbide particles, including two sizes of SiC particles, 10-12 μm and 25-30 μm, with a volume ratio (i.e., mass ratio) of 3:7), 15-25 μm chromite (the mass of which is 1% of the total mass of the aluminum powder and silicon carbide particles), and 15-25 μm pyrite (the mass of which is 2% of the total mass of the aluminum powder and silicon carbide particles), together with SiC grinding balls in a ball mill, add alcohol, and use SiC grinding balls (the mass ratio of 2-3 mm grinding balls to 8-9 mm grinding balls is 1:1). The mass ratio of the total powder to the grinding balls is 1:2; the mass ratio of the total powder to the alcohol is 2:1. The ball mill speed is 220-300 r / min, and the ball milling time is 1-1.5 h.

[0070] S2. Add polyvinyl pyrrolidone powder at a mass of 1% of the total mass of aluminum powder and silicon carbide powder, and continue ball milling at a speed of 300-350 r / min for 1-1.5 hours;

[0071] S3, after the ball milling is completed, the mixture is dried at a temperature of 70-100°C for 10 hours;

[0072] S4. The mixed and dried powder is placed in a mold for hot pressing and sintering at a temperature of 560°C, a pressure of 40 MPa, and a holding time of 15 minutes.

[0073] Example 3

[0074] As shown in FIG1 , this embodiment provides a method for preparing a ceramic reinforced aluminum-based composite material, comprising the following steps:

[0075] S0, take SiC particles (the volume is 55% of the total volume of aluminum powder and silicon carbide particles, including two sizes of SiC particles of 10-12 μm and 25-30 μm with a volume ratio (i.e., mass ratio) of 3:7), ultrasonically clean them in alcohol twice, each cleaning time is 1-15 minutes, and then dry them at a temperature of 80-100°C for 6 hours;

[0076] S1. Place 5-10 μm aluminum powder, S0-cleaned SiC particles, 15-25 μm chromite (the mass of which is 0.8% of the total mass of the aluminum powder and silicon carbide particles), 15-25 μm pyrite (the mass of which is 1.5% of the total mass of the aluminum powder and silicon carbide particles), and SiC grinding balls in a ball mill. Add alcohol and use SiC grinding balls (the mass ratio of 2-3 mm grinding balls to 8-9 mm grinding balls is 1:1). The mass ratio of the total powder to the grinding balls is 1:2; the mass ratio of the total powder to the alcohol is 2:1. The ball mill speed is 220-300 r / min, and the ball milling time is 1-1.5 h.

[0077] S2. Add polyvinyl pyrrolidone powder at a mass of 0.8% of the total mass of aluminum powder and silicon carbide powder, and continue ball milling at a speed of 300-350 r / min for 1-1.5 hours;

[0078] S3. After the ball milling is completed, the mixture is dried at a temperature of 90-120°C for 8 hours;

[0079] S4. The mixed and dried powder is placed in a mold for hot pressing and sintering at a temperature of 560°C, a pressure of 40 MPa, and a holding time of 10 minutes.

[0080] Example 4

[0081] This embodiment provides a method for preparing a ceramic reinforced aluminum-based composite material, comprising the following steps:

[0082] S0, take SiC particles (the volume is 52% of the total volume of aluminum powder and silicon carbide particles, including two sizes of SiC particles of 10-12 μm and 25-30 μm with a volume ratio (i.e., mass ratio) of 4:6), ultrasonically clean them twice in deionized water, each cleaning time is 15-30 minutes, and then dry them at a temperature of 100-120°C for 4 hours;

[0083] S1. Place 5-10 μm aluminum powder, S0-cleaned SiC particles, 15-25 μm chromite (the mass of which is 0.5% of the total mass of the aluminum powder and silicon carbide particles), 15-25 μm pyrite (the mass of which is 1% of the total mass of the aluminum powder and silicon carbide particles), and SiC grinding balls in a ball mill. Add alcohol and use SiC grinding balls (the mass ratio of 2-3 mm grinding balls to 8-9 mm grinding balls is 1:1). The mass ratio of the total powder to the grinding balls is 1:2; the mass ratio of the total powder to the alcohol is 2:1. The ball mill speed is 220-300 r / min, and the ball milling time is 1-1.5 h.

[0084] S2. Add polyvinyl pyrrolidone powder at a mass of 0.3% of the total mass of aluminum powder and silicon carbide powder, rotate at 300-350 r / min, and continue ball milling for 1-1.5 hours;

[0085] S3, after the ball milling is completed, the mixture is dried at a temperature of 70-100°C for 10 hours;

[0086] S4. The mixed and dried powder is placed in a mold for hot pressing and sintering at a temperature of 580°C, a pressure of 30 MPa, and a holding time of 15 minutes.

[0087] Example 5

[0088] This embodiment provides a method for preparing a ceramic reinforced aluminum-based composite material, comprising the following steps:

[0089] S0. Take SiC particles (the volume is 60% of the total volume of aluminum powder and silicon carbide particles, including two sizes of SiC particles of 10-12 μm and 25-30 μm with a volume ratio (i.e., mass ratio) of 3.5:6.5), ultrasonically clean them in alcohol twice, each cleaning time is 1-15 minutes, and then dry them at a temperature of 80-100°C for 6 hours;

[0090] S1. Place 5-10 μm aluminum powder, S0-cleaned SiC particles, 15-25 μm chromite (the mass of which is 0.5% of the total mass of the aluminum powder and silicon carbide particles), 15-25 μm pyrite (the mass of which is 1% of the total mass of the aluminum powder and silicon carbide particles), and SiC grinding balls in a ball mill. Add alcohol and use SiC grinding balls (the mass ratio of 2-3 mm grinding balls to 8-9 mm grinding balls is 1:1). The mass ratio of the total powder to the grinding balls is 1:2; the mass ratio of the total powder to the alcohol is 2:1. The ball mill speed is 220-300 r / min, and the ball milling time is 1-1.5 h.

[0091] S2. Add polyvinyl pyrrolidone powder at a mass of 0.3% of the total mass of aluminum powder and silicon carbide powder, rotate at 300-350 r / min, and continue ball milling for 1-1.5 hours;

[0092] S3, after the ball milling is completed, the mixture is dried at a temperature of 70-100°C for 10 hours;

[0093] S4. The mixed and dried powder is placed in a mold for hot pressing and sintering at a temperature of 560°C, a pressure of 20 MPa, and a holding time of 15 minutes.

[0094] Comparative Examples 1-8 used the same process steps as Example 1, except that no chromite, pyrite, and polyvinyl pyrrolidone were added during the preparation process. Other differences in the process steps are shown in Table 1.

[0095] Comparative Example 9 adopts the same process steps as Example 5, except that polyvinyl pyrrolidone is not added in S2. Other differences in the process steps are shown in Table 1.

[0096] Comparative Example 10 uses the same process steps as Example 5, except that no chromite and pyrite are added in S1. Other differences in the process steps are shown in Table 1.

[0097] Comparative Example 11 adopts the same process steps as Example 5, except that no pyrite is added in S1, the holding time is set to 15 minutes, and the other different process steps are shown in Table 1.

[0098] Comparative Example 12 adopts the same process steps as Example 5, except that no pyrite is added in S1, the holding time is set to 25 minutes, and the other different process steps are shown in Table 1.

[0099] Comparative Example 13 adopts the same process steps as Example 5, except that the mass of pyrite added in S1 is 0.5% of the total mass of aluminum powder and silicon carbide particles, and the holding time is set to 15 minutes.

[0100] Table 1 Specific process differences and performance test results of each embodiment and comparative example

[0101] The thermal conductivity, flexural strength, and thermal expansion coefficient of the composite materials prepared in each embodiment and comparative example were tested for samples with a relative density exceeding 98%. Comparative example samples with a relative density below 98% were not tested. The test results shown in Figures 2 and 3 and Table 1 show that:

[0102] Comparative Examples 1-8 omitted chromite, pyrite, and polyvinylpyrrolidone, and dry mixing was used in place of wet mixing in S2. The resulting composite materials exhibited low overall density, and uneven distribution of ceramic particles and aluminum powder. Furthermore, Comparative Examples 7 and 8 employed sintering temperatures exceeding 600°C, resulting in significant "sweating" during sintering, affecting the uniformity and shape of the product.

[0103] Referring to the composite material sample obtained in Example 1 shown in Figure 2, it can be seen that the surface is smooth and the components are evenly distributed. Referring to the composite material sample obtained in Example 3 shown in Figure 3, the surface is smooth, there is no obvious granularity, the texture is fine, and the color is uniform. Referring to Figure 4, the composite material sample obtained in Comparative Example 6 has black spots on the surface, indicating that the raw materials are not completely mixed and uniform. After polishing, the surface of the material shows concave and convex lines, indicating that the interface bonding is not ideal during sintering. Therefore, by comparing the test results of Comparative Examples 1-8 with Example 1, it can be seen that the wet mixing process is adopted in step S2, and polyvinyl pyrrolidone is added during ball milling, which can effectively improve the dispersion uniformity of the raw materials.

[0104] Comparing the performance test results of the composite materials of Example 5 and Comparative Example 10, it can be seen that the relative density of the composite materials was significantly improved after the addition of polyvinyl pyrrolidone. Referring to the electron micrograph of the composite material prepared in Example 5 at a scale of 100 μm shown in Figure 5, it can be seen that the composite material has good density, no obvious pores, and a relatively uniform particle distribution. Referring to the electron micrograph of the composite material prepared in Comparative Example 9 at a scale of 100 μm shown in Figure 6, it can be seen that the particle distribution is obviously uneven and the porosity is high. This indicates that the absence of polyvinyl pyrrolidone during ball milling has an adverse effect on the particle dispersibility of the prepared composite material.

[0105] Comparing the performance test results of the composite materials of Example 5 and Comparative Example 9, it can be seen that after adding chromite and pyrite, the flexural strength and thermal conductivity of the composite materials are significantly improved.

[0106] In addition, only one type of silicon carbide particle size is used in Comparative Examples 1-5, and dry mixing is used in S2, resulting in a lower relative density; wherein, the volume fraction of silicon carbide particles introduced during preparation in Comparative Examples 4 and 5 is above 55%. Compared with the samples with low volume fractions in Comparative Examples 1-3, the relative density of the samples in Comparative Examples 4 and 5 is lower. This is because ceramic particles exist in the composite material in the form of particles. The greater the proportion of ceramic particles, the lower the density of the composite material. Comparing the test results of Comparative Examples 4 and 5 with those of Comparative Example 6, it can be seen that the use of graded silicon carbide particles as a reinforcing phase can avoid the problem of reduced density caused by ceramic particles of a single particle size, and effectively improve the density of the composite material. From the results of Comparative Examples 4-6, it can be seen that when ceramic particles of a single particle size are used to prepare a composite material, it is difficult to prepare a composite material with a high silicon carbide volume fraction and high density.

[0107] Compared to Comparative Examples 4 and 5, Comparative Examples 6-8 employed the same graded silicon carbide particles as in the examples of the present invention, introducing a volume fraction of 55%. Although the performance of the final products was lower than that of the products prepared in the examples, the relative density of the products in Comparative Examples 6-8 was significantly improved compared to Comparative Examples 4 and 5. This demonstrates that employing a design with two silicon carbide particle sizes can significantly improve product density and introduce more reinforcing phases into the composite material, thereby reducing the composite material's coefficient of thermal expansion.

[0108] In Comparative Example 11, no pyrite was added, and the pressure sintering holding time was 15 minutes. In Comparative Example 12, no pyrite was added, and the pressure sintering holding time was 25 minutes. In Comparative Example 13, the mass of pyrite added was 0.5% of the total mass of the aluminum powder and silicon carbide particles, and the sintering holding time was set to 25 minutes. Comparing the product performance test data of Example 5 and Comparative Examples 11-13, it can be seen that the relative density of the product of Comparative Example 12 is greater than that of Comparative Example 11, indicating that increasing the pressure sintering holding time to 25 minutes is beneficial to improving the density of the product. Comparing the test data of Comparative Examples 12 and 13, it can be seen that after adding pyrite in Comparative Example 13, the relative density after pressure sintering and holding for 15 minutes exceeds the relative density of Comparative Example 12 without adding pyrite and holding for 15 minutes. Comparative Example 13, in which pyrite was added at a mass of 0.5% of the total mass of the aluminum and ceramic particles, its product performance test data was not as good as that of Example 5, indicating that adding an appropriate amount of pyrite can effectively reduce the hot pressing sintering time.

[0109] When the volume proportion of silicon carbide particles is 55.00%, the samples obtained by the same process steps are compared with Examples 2 and 3. In Example 2, the silicon carbide particles are directly wet-ground with aluminum powder without cleaning, and the density reaches 98.97%, the flexural strength is 386.2 MPa, the thermal conductivity is 232.7 W / (mk), and the thermal expansion coefficient is 13.7×10 -6K. In Example 3, the silicon carbide particles were first cleaned and dried before being wet-ground with aluminum powder, resulting in a density of 99.14%. It is clear that the relative density of the sample was improved after the ultrasonic cleaning step of the silicon carbide particles was added. Example 2 still had significantly better performance than the comparative example, indicating that even without the silicon carbide cleaning step, the preparation method provided by the embodiment of the present invention can produce a product with improved performance. However, after the SO silicon carbide cleaning step was added to Example 3, the product performance was further improved. By adjusting the various process parameters, in the optimal embodiment (Example 5), the relative density could reach 99.2%.

[0110] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0111] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0112] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A preparation method of a ceramic-reinforced aluminum matrix composite material, characterized in that, It includes the following steps: S1. Add silicon carbide grinding balls and a second solvent to aluminum powder, silicon carbide particles, chromite, and pyrite, and conduct ball milling and mixing in the first stage; The silicon carbide particles are composed of first silicon carbide particles and second silicon carbide particles, and the volume ratio of the first silicon carbide particles to the second silicon carbide particles is (3 - 4):(6 - 7). The particle size of the first silicon carbide particles is 10 - 12 μm, and the particle size of the second silicon carbide particles is 25 - 30 μm; The volume of the silicon carbide particles accounts for 55% - 60% of the total volume of the silicon carbide particles and the aluminum powder, and the particle size of the aluminum powder is 1 - 10 μm; S2. Add polyvinylpyrrolidone to the mixture obtained by ball milling in S1, and conduct ball milling and mixing in the second stage; S3. Mix the mixture obtained in S2 and then dry it; S4. Hot press and sinter the mixture obtained in S3, with the sintering temperature being 560 - 580 °C, the pressure being 20 - 40 MPa, and the heat preservation time being 10 - 15 min.

2. The preparation method of the ceramic-reinforced aluminum matrix composite material according to claim 1, wherein, It also includes: S0. Ultrasonically clean the silicon carbide particles in a first solvent, and dry them after cleaning; The first solvent includes one of alcohol or deionized water. The number of ultrasonic cleaning times is 1 - 2 times, and the cleaning time for each time is 1 - 30 min; the drying temperature after cleaning is 80 - 120 °C, and the time is 4 - 6 h.

3. The preparation method of the ceramic reinforced aluminum matrix composite material according to claim 1, characterized in that, In S1, the mass of the chromite is 0.5% - 1% of the total mass of the silicon carbide particles and the aluminum powder, and the particle size is 15 - 25 μm.

4. The preparation method of the ceramic-reinforced aluminum matrix composite material according to claim 1, characterized in that, In S1, the mass of the pyrite is 1% - 2% of the total mass of the silicon carbide particles and the aluminum powder, and the particle size is 15 - 25 μm.

5. The preparation method of the ceramic-reinforced aluminum matrix composite material according to claim 1, characterized in that, In S1, the second solvent includes alcohol, and the mass ratio of the raw materials to the second solvent is 2:1, and the mass ratio of the raw materials to the silicon carbide grinding balls is 1:

2.

6. The preparation method of the ceramic-reinforced aluminum matrix composite material according to claim 5, characterized in that, In S1, the silicon carbide grinding balls include first - sized grinding balls and second - sized grinding balls with a mass ratio of 1:

1. The particle size of the first - sized grinding balls is 2 - 3 mm, and the particle size of the second - sized grinding balls is 8 - 9 mm.

7. The preparation method of the ceramic-reinforced aluminum matrix composite material according to claim 1, wherein, In S2, the mass of the polyvinylpyrrolidone is 0.3% - 1% of the total mass of the silicon carbide particles and the aluminum powder.

8. [Corrected according to Rule 26 on 01.07.2024] The method for preparing a ceramic-reinforced aluminum matrix composite material according to any one of claims 5 to 7, characterized in that, In S1, the rotation speed of the first - stage ball milling is 220 - 300 r / min, and the time is 1 - 1.5 h; in S2, the rotation speed of the second - stage ball milling and mixing is 300 - 350 r / min, and the time is 1 - 1.5 h.

9. The preparation method of the ceramic reinforced aluminum matrix composite material according to claim 1, characterized in that, In S3, the drying temperature after mixing is 70 - 120 °C, and the time is 8 - 10 h.

10. A ceramic-reinforced aluminum matrix composite material, characterized in that, It is obtained by the preparation method of the ceramic - reinforced aluminum - matrix composite material as described in any one of claims 1 to 9.

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