Silicon carbide-diamond particle aluminum-based composite material and preparation method thereof

Abstract

The embodiment of the invention provides a silicon carbide-diamond particle aluminum-based composite material and a preparation method thereof.The preparation method comprises the steps that (X1) aluminum powder, silicon carbide particles and diamond particles with preset volume fractions are subjected to wet ball milling, dispersing and drying, and silicon carbide-diamond particle aluminum-based composite powder is obtained; and (X2) the silicon carbide-diamond particle aluminum-based composite powder obtained in the step (X1) is subjected to vacuum sintering, gradient heating is conducted in the vacuum sintering process, and the silicon carbide-diamond particle aluminum-based composite material is obtained. According to the embodiment of the invention, the adverse effect of impurity atoms on sintering in the sintering process can be reduced, and a brittle Al3C4 phase generated by mutual diffusion reaction of carbon atoms and aluminum atoms caused by high temperature is reduced, so that the problems of increased interface thermal resistance and relatively low density of the composite material are reduced; and the silicon carbide-diamond particle aluminum-based composite material with good interface bonding, high density and good thermal physical performance is obtained.

Description

Technical Field

[0001] The present invention relates to the field of material preparation, and particularly to a silicon carbide-diamond particle aluminum matrix composite material and a preparation method thereof. Background Art

[0002] With the increasingly diversified and complex development of aerospace and electronic devices, the requirements for material properties are becoming more and more stringent. Materials with high thermal conductivity, low expansion coefficient and high strength play a crucial role in ensuring the reliability and service life of satellite structural components. At the same time, when high-power density electronic devices are operating, the average heat flux density exceeds 15 W / cm 2 , and the huge amount of heat cannot be effectively dissipated, resulting in an increasing failure rate, which has become a bottleneck restricting the further development of electronic devices. With the development of technologies such as aerospace and electronic devices, in order to meet the requirements of new technologies for material properties, composite materials composed of multiple raw materials have begun to appear. The unique crystal structure of diamond enables its intrinsic thermal conductivity to reach up to 2000 W / m·K at most, and the thermal expansion coefficient is only 1.0×10 -6 K -1 . At the same time, diamond also has excellent mechanical properties and a low density. Therefore, diamond has become an ideal reinforcing phase for composite materials in the fields of aerospace equipment and electronic packaging devices, etc. However, in some cases, doping diamond will cause a decline in the thermophysical properties and mechanical properties of the composite material.

[0003] In summary, there is an urgent need to develop a new type of aluminum matrix composite material at present. The new type of aluminum matrix composite material is required to have good physical properties and thermophysical properties. Summary of the Invention

[0004] Therefore, based on the deficiencies of the prior art, the embodiments of the present invention provide a preparation method of a silicon carbide-diamond particle aluminum matrix composite material to prepare a silicon carbide-diamond particle aluminum matrix composite material with high density and good thermophysical properties.

[0005] The embodiments of the present invention provide a preparation method of a silicon carbide-diamond particle aluminum matrix composite material, including the steps of:

[0006] (X1) Wet ball milling, dispersing and drying aluminum powder, silicon carbide particles and diamond particles with preset volume fractions respectively to obtain a silicon carbide-diamond particle aluminum matrix composite powder. The wet ball milling specifically includes alternately rotating the ball mill clockwise and counterclockwise and stopping rotating during the alternation;

[0007] (X2) Vacuum sintering the silicon carbide-diamond particle aluminum matrix composite powder obtained in the step (X1), and performing gradient heating during the vacuum sintering to obtain a silicon carbide-diamond particle aluminum matrix composite material.

[0008] An embodiment of the present invention provides a silicon carbide-diamond particle aluminum matrix composite material, including the silicon carbide-diamond particle aluminum matrix composite material prepared by the preparation method of the silicon carbide-diamond particle aluminum matrix composite material described in any one of the above.

[0009] In some embodiments, the density of the silicon carbide-diamond particle aluminum matrix composite material is greater than or equal to 98.5%, the thermal conductivity is 270 W / m·K to 370 W / m·K, and the coefficient of thermal expansion is 5.5×10 -6 ·K -1 ~12.0×10 -6 ·K -1 。

[0010] The embodiments of the present invention at least include the following beneficial effects: The embodiments of the present invention can reduce the adverse effects of impurity atoms on sintering during the sintering process, reduce the mutual diffusion reaction between carbon atoms and aluminum atoms caused by high temperature to generate the brittle Al3C4 phase, and further reduce the problems of increased interfacial thermal resistance and low density of the composite material caused thereby, which is beneficial to making the temperature distribution of the material more uniform, reducing the risk of cracks or deformation of the material due to excessive temperature difference between the surface and the inside, and is also beneficial to reducing material deformation and stress concentration, so that a silicon carbide-diamond particle aluminum matrix composite material with good interfacial bonding, high density and good thermophysical properties can be obtained. The silicon carbide-diamond particle aluminum matrix composite material provided by the embodiments of the present invention introduces a small amount of diamond particles as the second-phase reinforcing particles in the silicon carbide reinforcing phase, which not only effectively exerts the excellent thermophysical properties of diamond, improves the thermal conductivity of the silicon carbide-diamond particle aluminum matrix composite material, but also reduces the cost. The obtained silicon carbide-diamond particle aluminum matrix composite material has high density and good interfacial bonding, and the hybrid synergistic effect of silicon carbide and diamond significantly enhances the thermophysical properties of the silicon carbide-diamond particle aluminum matrix composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic flow chart of a preparation method of a silicon carbide-diamond particle aluminum matrix composite material provided by an embodiment of the present invention.

[0012] Figure 2 is Figure 1 a specific schematic flow chart of step X1 in the preparation method of the silicon carbide-diamond particle aluminum matrix composite material shown.

[0013] Figure 3 is Figure 1 a specific schematic flow chart of step X2 in the preparation method of the silicon carbide-diamond particle aluminum matrix composite material shown.

[0014] Figure 4Morphology diagrams of aluminum powder, silicon carbide particles, and diamond particles before and after ball milling used in Example 1.

[0015] Figure 5 Scanning electron microscope images of silicon carbide-diamond particle aluminum matrix composites prepared by the method of Example 1.

[0016] Figure 6 Scanning electron microscope images of silicon carbide-diamond particle aluminum matrix composites prepared by the method of Example 2.

[0017] Figure 7 Scanning electron microscope images of silicon carbide-diamond particle aluminum matrix composites prepared by the method of Example 3.

[0018] Figure 8 Scanning electron microscope images of silicon carbide-diamond particle aluminum matrix composites prepared by the method of Example 4.

[0019] Figure 9 Scanning electron microscope images of silicon carbide-diamond particle aluminum matrix composites prepared by the method of Example 5. Detailed implementation manners

[0020] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the detailed implementation manners of the present invention in conjunction with the accompanying drawings.

[0021] To enable those of ordinary skill in the art to better understand the technical solutions of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0022] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products, or devices.

[0023] It should also be noted that the division of multiple embodiments in the present invention is only for the convenience of description and should not constitute a special limitation. The features in various embodiments can be combined and cited from each other without contradiction.

[0024] With the rapid development of aerospace and electronic device technologies, the requirements for material properties are becoming increasingly stringent, especially in terms of high thermal conductivity, low coefficient of thermal expansion, and high strength. Due to its excellent high-temperature stability and high thermal conductivity, silicon carbide particles are widely used to improve the thermal conductivity of aluminum matrix composites. However, although silicon carbide particles can effectively improve the thermal conductivity and thermal expansion resistance of aluminum matrix composites, their low interfacial wettability limits the further improvement of the materials. The unique crystal structure of diamond enables its intrinsic thermal conductivity to reach up to 2000 W / m·K, and its coefficient of thermal expansion is only 1.0×10 -6 K -1 . At the same time, diamond also has excellent mechanical properties and a low density, making it an ideal reinforcing phase for composites in fields such as aerospace equipment and electronic packaging devices. However, the carbon atom dangling bonds on the diamond surface will adsorb impurity atoms in the environment and self-couple with adjacent carbon atoms, thereby reducing its surface energy and forming a stable surface. This results in a wetting angle between diamond and liquid metal aluminum exceeding 140°, which in turn affects the interfacial bonding between diamond and aluminum. When the composite preparation temperature is too high or affected by stress, the carbon atoms of diamond and the aluminum atoms in the aluminum matrix diffuse into each other and react with aluminum at the interface to form a brittle Al3C4 phase, which not only increases the interfacial thermal resistance, destroys the interfacial structure, but also causes the thermophysical and mechanical properties of the composite to decline, resulting in a lower density and particle agglomeration of the composite.

[0025] Based on the above technical problems, referring to Figure 1 , an embodiment of the present invention provides a method for preparing a silicon carbide-diamond particle aluminum matrix composite, including the steps of:

[0026] Step X1: Wet ball mill, disperse, and dry aluminum powder, silicon carbide particles, and diamond particles with preset volume fractions respectively to obtain a silicon carbide-diamond particle aluminum matrix composite powder. The wet ball milling specifically includes alternately rotating the ball mill clockwise and counterclockwise and stopping during the alternation.

[0027] Step X2: Vacuum sinter the silicon carbide-diamond particle aluminum matrix composite powder obtained in Step X1, and perform gradient heating during the vacuum sintering process to obtain a silicon carbide-diamond particle aluminum matrix composite.

[0028] In step X1, aluminum powder, silicon carbide particles, and diamond particles are incorporated into the liquid medium of wet ball milling to perform wet ball milling. By wrapping the aluminum powder, silicon carbide particles, and diamond particles with the liquid medium, their contact with oxygen is reduced, thereby decreasing the oxygen content of the obtained silicon carbide-diamond particle aluminum-based composite powder and endowing the silicon carbide-diamond particle aluminum-based composite powder with high activity. Through the physicochemical effects during wet ball milling, dispersion, and drying, it helps to disperse and break up agglomerated particles, evenly disperse the silicon carbide particles in the aluminum-based powder, and improve the uniformity of particle distribution in the composite powder. At the same time, it also helps to introduce microdefects on the surface of diamond particles or increase the surface energy of diamond particles, thereby enhancing their chemical activity.

[0029] During the wet ball milling process, intermittent rotation during alternation is beneficial for reducing the probability of overheating, minimizing excessive wear of the composite powder, and improving the mixing effect. First of all, the friction between the ball milling medium and the composite powder during wet ball milling generates heat. Therefore, if continuous ball milling is carried out, the temperature of the ball milling medium and the composite powder may rise, leading to sintering of the powder or excessive particle deformation, thus affecting the sintering of the composite powder. Therefore, intermittent rotation during the alternation of clockwise and counterclockwise ball milling helps to cool the ball milling medium, aluminum powder, silicon carbide particles, and diamond particles, reducing the probability of degradation of the composite powder material caused by overheating and maintaining the high activity of the composite powder. Secondly, during the intermittent rotation, the contact between the ball milling medium and the composite powder decreases, which is beneficial for reducing excessive wear of the composite powder and refining the composite powder, reducing the introduction of impurity atoms, and maintaining the high activity of the composite powder. If directly reversed, it may cause unnecessary wear of the composite powder, thereby affecting the particle size and distribution of the composite powder. Then, during the intermittent rotation process, the relative movement between the composite powder and the ball milling medium slows down, which helps to redistribute the particles in the composite powder and promote full contact and uniform mixing between the particles of the composite powder.

[0030] In step X2, vacuum sintering causes the silicon carbide-diamond particle aluminum matrix composite powder to sinter into a silicon carbide-diamond particle aluminum matrix composite material. During the sintering process, maintaining a vacuum sintering environment is beneficial for reducing the introduction of other atoms such as oxygen into the silicon carbide-diamond particle aluminum matrix composite powder during sintering, thereby being able to reduce the probability that the carbon atom dangling bonds on the surface of the diamond particles adsorb impurity atoms in the environment and self-close-couple with adjacent carbon atoms. Furthermore, it reduces the surface energy of the diamond particles, enables the diamond particles to form a stable surface, resulting in a wetting angle between the diamond and the liquid metal aluminum exceeding 140°, and affecting the probability of interface bonding between the diamond and the aluminum. At the same time, during the sintering process, the sintering temperature of the silicon carbide-diamond particle aluminum matrix composite powder is lower than the melting point of aluminum, which is further beneficial for reducing the probability of the brittle Al3C4 phase formed by the mutual diffusion reaction of carbon atoms and aluminum atoms caused by high temperature, so as to reduce the problems of increased interface thermal resistance and lower density of the composite material caused thereby. Moreover, vacuum sintering is carried out in a gradient heating manner, which is beneficial for making the temperature distribution of the material more uniform, reducing the risk of cracks or deformation of the material due to excessive temperature difference between the surface and the inside; and is also beneficial for reducing material deformation and stress concentration, and further beneficial for improving the density and thermophysical properties of the silicon carbide-diamond particle aluminum matrix composite material. In addition, controlling the temperature of vacuum sintering can accelerate the preparation process, reduce the sintering time, and improve production efficiency. The characteristics of low vacuum sintering temperature and short time not only help to save energy, but also can maintain the overall stability of the material, further enhance the interface bonding force between the diamond particles and the aluminum matrix, and improve the durability and stability of the composite material

[0031] In the embodiment of the present invention, aluminum powder, silicon carbide particles and diamond particles are wet ball milled, dispersed and dried to prepare a highly active silicon carbide-diamond particle aluminum matrix composite powder. Then, the silicon carbide-diamond particle aluminum matrix composite powder is further subjected to gradient heating vacuum sintering. In this way, the adverse effects of impurity atoms on sintering during the sintering process can be reduced, the probability of the brittle Al3C4 phase formed by the mutual diffusion reaction of carbon atoms and aluminum atoms caused by high temperature can be reduced, and further the problems of increased interface thermal resistance and lower density of the composite material caused thereby can be reduced; it is beneficial for making the temperature distribution of the material more uniform, reducing the risk of cracks or deformation of the material due to excessive temperature difference between the surface and the inside; and is also beneficial for reducing material deformation and stress concentration; at the same time, by alternately rotating the ball mill clockwise and counterclockwise and stopping the rotation during the alternation for wet ball milling, it helps the particles in the silicon carbide-diamond particle aluminum matrix composite powder to fully contact and mix evenly, and is beneficial for making the silicon carbide-diamond particle aluminum matrix composite powder highly active. Therefore, the preparation method of the embodiment of the present invention can obtain a silicon carbide-diamond particle aluminum matrix composite material with good interface bonding, high density and good thermophysical properties.

[0032] In some specific embodiments, in step X2, the silicon carbide-diamond particle aluminum matrix composite powder is placed in a mold, so that the silicon carbide-diamond particle aluminum matrix composite powder can be sintered to form a silicon carbide-diamond particle aluminum matrix composite material with a specific shape. Specifically, the inner liner, punch and gasket of the graphite mold are taken out, and boron nitride release agent is sprayed on the inner wall of the inner liner and the surfaces of the punch and gasket in contact with the composite powder. After the alcohol in the release agent has completely evaporated, the inner liner, punch and gasket are reassembled into the graphite mold. A small amount of composite powder is taken out and filled into the inner liner of the graphite mold, and the filling amount is 1 / 3 of the volume of the inner liner. After filling, sintering is carried out.

[0033] Specifically, referring to Figure 3 , step X2 specifically includes:

[0034] Step X21: Heating in the first stage: Raise the temperature to 300°C - 400°C at a heating rate of 6°C / min - 10°C / min;

[0035] Step X22: Insulation in the first stage: 10 min - 30 min;

[0036] Step X23: Heating in the second stage: Continue to raise the temperature to 500°C - 600°C at a rate of 8°C / min - 10°C / min;

[0037] Step X24: Insulation in the second stage: Insulate for 1 h - 3 h;

[0038] Step X25: End heating and carry out cooling.

[0039] It can be understood that steps X21 - X25 are sub-steps of step X2.

[0040] By performing the above-mentioned vacuum sintering with gradient heating, a small amount of diamond particles are introduced as the second-phase reinforcing particles in the silicon carbide reinforcement phase, which not only effectively exerts the excellent thermophysical properties of diamond and improves the thermal conductivity of the silicon carbide-diamond particle aluminum matrix composite material, but also reduces the cost. The obtained silicon carbide-diamond particle aluminum matrix composite material has high density and good interfacial bonding, and the hybrid synergistic effect of silicon carbide and diamond significantly enhances the thermophysical properties of the silicon carbide-diamond particle aluminum matrix composite material. By adjusting different parameters during the heating process, the density and thermophysical properties of the obtained silicon carbide-diamond particle aluminum matrix composite material can also be adjusted.

[0041] Furthermore, step X2 also includes:

[0042] In step X23, a pressure of 20 MPa to 25 MPa is applied to the silicon carbide-diamond particle aluminum matrix composite powder, and during the heating process, the pressure applied to the silicon carbide-diamond particle aluminum matrix composite powder is increased to 50 MPa to 55 MPa at a rate of 1 MPa / min to 1.5 MPa / min; in step X25, when cooling to a temperature of 400 °C, the pressure applied to the silicon carbide-diamond particle aluminum matrix composite powder is stopped, and then the cooling continues.

[0043] Applying pressure to the silicon carbide-diamond particle aluminum matrix composite powder can significantly improve the density of the material, reduce the porosity, improve the uniformity of particle distribution, effectively avoid particle agglomeration, so that the composite material has a more uniform microstructure. Secondly, the presence of pressure can promote an increase in the interfacial contact area between the particles and the aluminum matrix, further promoting the plastic flow and atomic diffusion of the silicon carbide-diamond particle aluminum matrix composite powder at high temperatures, enabling the aluminum powder to quickly wrap the diamond reinforcement particles, thereby enhancing the interfacial reaction efficiency, forming a higher-strength interfacial bond, and reducing the possibility of particle detachment and interfacial defects. In addition, applying pressure can also effectively improve the mechanical properties of the composite material, including tensile strength, hardness, and toughness, because higher density and stronger interfacial bond significantly reduce the failure risk caused by stress concentration and weak bonding regions. On the other hand, the action of pressure also has a positive impact on the thermal conductivity performance. By reducing the pore and interfacial thermal resistance and enhancing the continuity of the heat conduction path between the particles, the thermal conductivity of the composite material is improved. In addition, applying pressure can also shorten the sintering time, reduce the sintering temperature, and improve the dimensional accuracy and stability of the composite material.

[0044] In some embodiments, referring to Figure 2 , step X1 specifically includes:

[0045] Step X11: Wet ball milling is carried out on aluminum powder, silicon carbide particles, and diamond particles with preset volume fraction ratios under a protective atmosphere to obtain a composite powder. The wet ball milling specifically includes alternately rotating the ball mill clockwise and counterclockwise and stopping when alternating.

[0046] Step X12: The composite powder obtained in step X11 is placed in a protective atmosphere for ultrasonic dispersion to obtain a dispersed composite powder.

[0047] Step X13: The dispersed composite powder obtained in step X12 is placed in a vacuum environment for drying treatment to obtain the silicon carbide-diamond particle aluminum matrix composite powder.

[0048] The purities of the aluminum powder, silicon carbide particles, and diamond particles used in step X11 are all greater than or equal to 99.95%. By alternately performing clockwise ball milling and counterclockwise ball milling in step X11, the average particle size of the obtained composite powder can be reduced, and the agglomeration of the composite powder can be reduced, increasing the dispersibility of the composite powder.

[0049] Step X12: After wet ball milling in step X11, the composite powder is mixed with the liquid medium added in the wet ball milling to form a liquid medium slurry, and the liquid medium slurry is ultrasonically dispersed to improve the dispersibility of the composite powder in the liquid medium, making the particle distribution in the composite powder more uniform.

[0050] In steps X11 and X12, both wet ball milling and ultrasonic dispersion are carried out in a protective atmosphere to reduce the oxidation of the composite powder, reduce the possibility of an increase in the oxygen content in the composite powder, and maintain the high activity of the composite powder.

[0051] Specifically, high-purity argon is used to form a protective atmosphere, which specifically includes evacuating the environment where wet ball milling is located, and then filling it with high-purity argon until the pressure in the environment where wet ball milling is located is the same as the external air pressure, repeating the above operation at least twice; evacuating the environment where ultrasonic dispersion is located, and then filling it with high-purity argon until the pressure in the environment where the composite powder is dispersed is the same as the external air pressure, repeating the above operation at least twice.

[0052] Step X13: Drying is carried out in a vacuum environment to accelerate the evaporation rate of the liquid medium in wet ball milling, thereby reducing the drying time and improving the drying efficiency; at the same time, it can also reduce the oxygen content in the environment, thereby reducing the probability of oxidation of the silicon carbide-diamond particle aluminum matrix composite powder, which is beneficial to maintaining the high activity of the silicon carbide-diamond particle aluminum matrix composite powder.

[0053] In this way, the obtained silicon carbide-diamond particle aluminum matrix composite powder has the properties of low agglomeration, high activity, low oxygen content, and uniform particle size. These properties enable the silicon carbide-diamond particle aluminum matrix composite powder to effectively reduce the sintering temperature during vacuum sintering in step X2, further reduce the generation of the Al3C4 phase, enhance the interfacial bonding between particles, thereby improving the density and thermophysical properties of the silicon carbide-diamond particle aluminum matrix composite material.

[0054] In some embodiments, the average particle size of the aluminum powder in step X11 is 25 μm to 30 μm; the average particle size of the silicon carbide particles is 250 μm to 300 μm; and the average particle size of the diamond particles is 200 μm to 250 μm. In this way, the silicon carbide particles and the diamond particles can be evenly dispersed in the aluminum powder. If the particle sizes of the silicon carbide particles and the diamond particles are too large, it will lead to insufficient crushing of the aluminum powder, silicon carbide particles and diamond particles during the ball milling process, and it will be difficult to obtain aluminum powder with finer particle sizes. If the particle sizes of the silicon carbide particles and the diamond particles are too small, the oxygen introduced by the particles will also increase, and it will be difficult to obtain silicon carbide-diamond particle aluminum-based composite powder with a low oxygen content. Therefore, using aluminum powder, silicon carbide particles and diamond particles with the above-mentioned particle sizes helps to prepare silicon carbide-diamond particle aluminum-based composite powder with low agglomeration, high activity, low oxygen content and uniform particle size.

[0055] Specifically, in step X1, the morphology of the aluminum powder particles is spherical. Spherical aluminum powder particles have good fluidity and uniformity, which can promote the dispersibility during the mixing process. In the embodiments using a mold for sintering, the spherical aluminum powder particles can easily fill the mold, which helps to reduce the generation of pores or defects in the sintered silicon carbide-diamond particle aluminum-based composite material; the morphology of the silicon carbide particles is irregular. Irregular silicon carbide particles have a larger contact area, which is beneficial to enhancing the interfacial bonding ability with the aluminum matrix during vacuum sintering, and the irregular silicon carbide particles are inexpensive, which is beneficial to reducing the cost of preparing the silicon carbide-diamond particle aluminum-based composite material; the morphology of the diamond particles is a near-spherical polyhedron, which helps to reduce the packing resistance between particles, improve the dispersibility of particles, and then optimize the uniformity of the composite material. Its polyhedron shape can provide a larger interfacial contact area, which can promote good bonding between the reinforcing particles and the aluminum matrix during sintering, thereby improving the thermal conductivity of the composite material.

[0056] In some embodiments, the preset volume fraction ratio of the aluminum powder, silicon carbide particles and diamond particles is 11:5 to 7:2 to 4. In this way, it is beneficial for the particles of the silicon carbide-diamond particle aluminum-based composite powder to be evenly dispersed during sintering, thereby improving the uniformity and overall performance of the composite material. In addition, by adjusting the ratio between the silicon carbide particles and the diamond particles, the thermal properties of the silicon carbide-diamond particle aluminum-based composite material can be adjusted to meet the requirements of different application scenarios.

[0057] In some specific embodiments, the duration of each clockwise rotation and each counterclockwise rotation of the ball milling in step X11 is 3 min to 5 min respectively; the stop time during the alternation is 1 min to 2 min, and the total ball milling time is 6 h. The time of a single ball milling does not exceed 5 min, which is beneficial to reducing the probability of phenomena such as agglomeration, coalescence and excessive cold welding of the composite powder, and reducing the impact on the crushing effect of aluminum powder, silicon carbide particles and diamond particles; the time of a single ball milling is greater than or equal to 2 min, so that the aluminum powder, silicon carbide particles and diamond particles can be sufficiently ball milled to obtain a composite powder with a smaller particle size.

[0058] The stop time of the ball milling during the alternation is 1 min to 2 min, which helps to fully promote the mixing and distribution of aluminum powder, silicon carbide particles and diamond particles, and is beneficial to effectively reducing the heat generated during the ball milling process, thereby helping to maintain the high activity of the composite powder; at the same time, it can also reduce the unnecessary refinement of the composite powder, reduce the probability of agglomeration, and reduce wear, and helps the ball milling to reach the required motion state again and maintain the ball milling efficiency. When the stop time of the ball milling is less than one minute, it is difficult to fully promote the mixing and distribution of aluminum powder, silicon carbide particles and diamond particles, resulting in poor uniformity of the composite powder, and at the same time, it may be difficult to effectively reduce the temperature during the ball milling process, and thus it is difficult to reduce the overheating problem. When the stop time of the ball milling is higher than two minutes, it will cause the composite powder to be exposed to the static state for a long time, which may lead to unnecessary refinement of the composite powder, agglomeration or greater wear, and it may take a long time to reach the required motion state again during the restart, thus reducing the efficiency.

[0059] In some embodiments, in step X1, the rotation speed of the ball milling is 100 rpm to 150 rpm, which is beneficial to the uniform dispersion of silicon carbide particles and diamond particles with low oxygen content, and at the same time makes the particle size of the aluminum powder smaller. If the rotation speed of the ball milling is too low, the particle size of the composite powder will increase and the activity will decrease; if the rotation speed of the ball milling is too high, the wear of the ball milling tank will be aggravated, and at the same time the particle size of the silicon carbide and diamond particles will decrease, resulting in an increase in the oxygen content in the obtained composite powder, reducing the activity of the composite powder, and thus having an adverse effect on the sintering of the diamond particle aluminum matrix composite powder.

[0060] In some specific embodiments, the ball-to-material ratio of the ball milling is 2 to 3:1. In this way, it helps to improve the wear effect of aluminum powder, silicon carbide particles and diamond particles during the ball milling process. A higher ball-to-material ratio can increase the number of impacts between the ball milling medium and the composite during the grinding process, promote the refinement and uniform distribution of the composite powder; at the same time, limit the maximum value of the ball-to-material ratio to avoid over-grinding, so that the particles become too fine, thereby reducing the probability of introducing impurity atoms such as oxygen atoms.

[0061] In some embodiments, in step X11, the liquid medium for wet ball milling is absolute ethanol. By using absolute ethanol, the composite powder can be further separated from the external environment to further prevent the oxidation of the composite powder; ethanol is volatile and can take away part of the heat of the composite powder during wet ball milling, which is beneficial to reducing the probability of cold welding and the like during wet ball milling; and when using absolute ethanol, it is convenient to dry the composite powder.

[0062] In some embodiments, in step X12, the time for ultrasonic dispersion is 1 h to 4 h to ensure that the slurry formed by the liquid medium for ball milling and the composite powder can be fully dispersed.

[0063] In some embodiments, in step X13, the initial temperature in the drying process is 30°C to 40°C, and the temperature is increased at a rate of 5°C to 8°C every 2 h to 4 h until the temperature reaches 50°C to 60°C, and then dried for 24 h to 48 h. In this way, by gradually increasing the temperature during the drying process, the temperature distribution of the composite powder can be made more uniform, the stress concentration of the composite powder can be reduced, and the drying effect can be improved. Gradually increasing the temperature during the drying process is beneficial to reducing the sharp change in the surface and internal temperature of the composite powder, reducing the accumulation of internal stress caused by uneven temperature during the drying process, and thus reducing the possibility of deformation or rupture of the composite powder; gradient heating helps to remove moisture more evenly, avoids the surface rupture of the composite powder caused by too fast local moisture evaporation, and at the same time can improve the drying uniformity of the surface and inside of the composite powder, thereby optimizing the drying effect of the composite powder.

[0064] In some embodiments, in step X13, the vacuum degree of the vacuum environment is -0.1 MPa, and during the drying process, every 30 min to 40 min, the vacuum degree of the vacuum environment is pumped to -0.1 MPa again. During the drying process, since water and the liquid medium for wet ball milling will volatilize, the vacuum degree of the vacuum environment will be reduced, affecting the drying speed and drying effect. Therefore, every 30 min to 40 min, pumping the vacuum degree of the vacuum environment to -0.1 MPa again helps to improve the drying speed and drying effect during the drying process.

[0065] Embodiments of the present invention also provide a silicon carbide-diamond particle aluminum matrix composite, including the silicon carbide-diamond particle aluminum matrix composite prepared by the preparation method of the silicon carbide-diamond particle aluminum matrix composite described in any one of the above. The silicon carbide-diamond particle aluminum matrix composite provided by the embodiments of the present invention introduces silicon carbide reinforcing phase into the aluminum matrix, and at the same time introduces diamond particles as the second-phase reinforcing particles, which not only effectively exerts the excellent thermophysical properties of diamond, improves the thermal conductivity of the silicon carbide-diamond particle aluminum matrix composite, but also reduces the cost. The obtained silicon carbide-diamond particle aluminum matrix composite has high density and good interfacial bonding, and the hybrid synergistic effect of silicon carbide and diamond significantly enhances the thermophysical properties of the silicon carbide-diamond particle aluminum matrix composite.

[0066] In some embodiments, the density of the silicon carbide-diamond particle aluminum matrix composite is greater than or equal to 98.5%, the thermal conductivity is 270 W / m·K to 370 W / m·K, and the coefficient of thermal expansion is 5.5×10 -6 ·K -1 ~12.0×10 -6 ·K -1 。

[0067] Hereinafter, the preparation method of the silicon carbide-diamond particle aluminum matrix composite provided by the present invention will be described in detail with reference to Examples 1 to 3.

[0068] Example 1

[0069] A) Take raw materials with a purity of over 99.95%: 75.2 g of aluminum powder, 57.1 g of silicon carbide particles, and 17.7 g of diamond particles. The average particle size of the aluminum powder is 25 μm, and the average particle sizes of the silicon carbide particles and diamond particles are 300 μm and 200 μm respectively. The volume ratio of the aluminum powder, silicon carbide particles, and diamond particles is 11:7:3. Put the prepared raw materials into an alumina ball milling tank, add 300 g of alumina milling beads, and use anhydrous ethanol as the ball milling medium. The addition amount of anhydrous ethanol is 1 / 2 of the volume of the ball milling tank. Use an alumina ball milling tank with a capacity of 1 L. After loading the raw material powder and anhydrous ethanol, seal it with a sealing bolt. After sealing, close the intake valve on the upper cover of the ball milling tank, open the exhaust valve, and use a small vacuum pump to evacuate the tank to a vacuum with a vacuum degree of -0.1 MPa. Then close the exhaust valve, connect the argon gas pipeline to the intake valve and open it, and fill the tank with high-purity argon until the internal and external air pressures are balanced. Next, open the exhaust valve and keep the argon gas discharging from the exhaust valve for 5 min. Repeat the steps after sealing the ball milling tank twice. Then close the intake valve and exhaust valve of the ball milling tank, and install the ball milling tank on a QXQM-16 all-round planetary ball mill. Set the ball milling speed to 100 rpm, and the total running time of the equipment is 6 h. Stop rotating for 1 min every 5 min of operation, and switch the rotation direction each time the ball mill stops rotating; for example, switch the ball mill from clockwise rotation to counterclockwise rotation, continue to run for 5 min after switching, then stop rotating for 1 min, and after stopping, switch the ball mill from counterclockwise rotation to clockwise rotation.

[0070] See Figure 4 , where Figure 4 (a) is the original morphology diagram of the aluminum powder; Figure 4 (b) is the original morphology diagram of the silicon carbide particles; Figure 4 (c) is the original morphology diagram of the diamond particles; Figure 4 (d) is the morphology diagram of the silicon carbide particles and aluminum powder after wet ball milling; Figure 4 (e) is the morphology diagram of the diamond particles and aluminum after wet ball milling.

[0071] It can be seen from Figure 4 that after ball milling by the method of Example 1, the silicon carbide particles and diamond particles have a crushing effect on the aluminum powder, significantly reducing the particle size of the aluminum powder. Since the hardness of silicon carbide is lower than that of diamond, the hardness of the silicon carbide particles is less than that of the diamond particles, and the change range of its particle size is also greater than that of the diamond particles.

[0072] B) After the ball milling is completed, evacuate the glove box to a vacuum of -0.1 MPa, and then introduce high-purity argon until it is balanced with the external air pressure. This process is repeated twice to ensure that the oxygen content in the glove box is maintained at a low level. Open the ball milling tank in the glove box with a high-purity argon atmosphere, and separate the absolute ethanol and the ball milling beads from the mixed raw material powder through a sieve. Place the separated absolute ethanol slurry in a stainless steel tray and put it into the ultrasonic cleaner in the glove box for 4 h of ultrasonic oscillation dispersion.

[0073] C) Put the dispersed slurry into a small high-temperature vacuum drying oven in the glove box, evacuate the vacuum to -0.1 MPa, and set the heating temperature to 50 °C. Restart the mechanical pump every 1 h to restore the vacuum to -0.1 MPa for 6 h. When the vacuum no longer drops, introduce high-purity argon into the drying oven, balance it to atmospheric pressure, turn off the heating function, take out the powder and put it into a vacuum bag, and silicon carbide-diamond particle aluminum matrix composite powder without agglomeration and with uniform particle size can be obtained.

[0074] D) First, open the intake valve of the vacuum hot pressing sintering furnace. After the pressure in the furnace is balanced with the outside, open the furnace door, take out the graphite mold and put it into a stainless steel tray. Take out the mold liner, punch and gasket, and spray boron nitride release agent on the inner wall of the liner and the surfaces of the punch and gasket that come into contact with the silicon carbide-diamond particle aluminum matrix composite powder. After the alcohol in the release agent has completely evaporated, reassemble the liner, punch and gasket into the graphite mold. Take out a small amount of composite powder from the vacuum bag and fill it into the liner of the graphite mold, and the filling amount is 1 / 3 of the liner volume. Then put the graphite mold into the vacuum hot pressing sintering furnace, turn on the vacuum pump, and evacuate the vacuum in the furnace to 0 MPa. Close and fasten the furnace door. The vacuum hot pressing sintering process is as follows: First, heat it at a heating rate of 10 °C / min to 300 °C, keep it warm for 30 minutes, then apply a pressure of 25 MPa to the silicon carbide-diamond particle aluminum matrix composite powder in the graphite mold, and then increase the pressure to 55 MPa at a rate of 1 MPa / min, while continuing to heat at a rate of 10 °C / min to 580 °C, end the heating after keeping it warm for 2 hours, and cool it with the furnace. When the temperature drops to 400 °C, release the pressure applied to the silicon carbide-diamond particle aluminum matrix composite powder, and continue to cool it with the furnace to room temperature to complete the sintering process. See Figure 5 ., the surface of the composite material is clean and tidy, without obvious holes, and silicon carbide and diamond particles are evenly dispersed in the aluminum matrix, but most of the silicon carbide particles protrude on the surface of the matrix. The density of the obtained silicon carbide-diamond reinforced aluminum matrix composite material is 99.2%, the thermal conductivity is 353 W / m·K, and the thermal expansion coefficient is 5.8×10 -6 K -1 ~11.6×10 -6 K -1 .

[0075] Example 2

[0076] A) Take raw materials with a purity of over 99.95%: 75.2 g of aluminum powder, 57.1 g of silicon carbide particles, and 17.7 g of diamond particles. The average particle size of the aluminum powder is 25 μm, and the average particle sizes of the silicon carbide particles and diamond particles are 300 μm and 200 μm respectively. The volume ratio of the aluminum powder, silicon carbide particles, and diamond particles is 11:7:3. Put the prepared raw materials into an alumina ball mill tank, add 300 g of alumina ball mill beads, and use anhydrous ethanol as the ball milling medium. The addition amount of anhydrous ethanol is 1 / 2 of the volume of the ball mill tank. Use an alumina ball mill tank with a capacity of 1 L. After loading the raw material powder and anhydrous ethanol, seal it with a sealing bolt. After sealing, close the intake valve on the upper cover of the ball mill tank, open the exhaust valve, and use a small vacuum pump to evacuate the tank to a vacuum with a vacuum degree of -0.1 MPa. Then close the exhaust valve, connect the argon gas pipeline to the intake valve and open it, and fill the tank with high-purity argon gas until the internal and external air pressures are balanced. Next, open the exhaust valve and keep the argon gas discharging from the exhaust valve for 5 min. The steps after sealing the ball mill tank are repeated twice. Then close the intake valve and exhaust valve of the ball mill tank, and install the ball mill tank on a QXQM-16 all-round planetary ball mill. Set the ball milling speed to 100 rpm, and the total running time of the equipment is 6 h. Stop rotating for 1 min every 5 min of operation, and at the same time change the rotation direction of the ball mill.

[0077] B) After the ball milling is completed, before using the glove box, evacuate the vacuum degree in the glove box to -0.1 MPa first, and then introduce high-purity argon gas into the glove box until the air pressure in the glove box is equal to the external air pressure. This process is repeated twice to ensure that the oxygen content in the glove box is maintained at a low level. Open the ball mill tank in the inert gas glove box, and separate the anhydrous ethanol containing the composite powder from the ball mill beads through a sieve. Place the separated anhydrous ethanol slurry on a stainless steel tray and put it into an ultrasonic cleaner in the glove box for 4 h of ultrasonic oscillation dispersion.

[0078] C) Put the dispersed slurry into a small high-temperature vacuum drying oven in the glove box, evacuate the vacuum degree to -0.1 MPa, and set the heating temperature to 50 °C. Restart the mechanical pump every 1 h to restore the vacuum degree to -0.1 MPa, and continue for 6 h. When the vacuum degree no longer drops, introduce high-purity argon gas into the drying oven to balance to atmospheric pressure, turn off the heating function, take out the powder and put it into a vacuum bag, and silicon carbide-diamond particle aluminum-based composite powder without agglomeration and with uniform particle size can be obtained.

[0079] D) First, open the intake valve of the vacuum hot pressing sintering furnace. After the pressure inside the furnace is balanced with the outside, open the furnace door, take out the graphite mold and place it in a stainless steel tray. Take out the mold liner, punch and gasket, and spray boron nitride release agent on the inner wall of the liner and the surfaces of the punch and gasket that come into contact with the composite powder. After the alcohol in the release agent has completely evaporated, reassemble the liner, punch and gasket into the graphite mold. Take out a small amount of composite powder from the vacuum bag and fill it into the liner of the graphite mold, with the filling amount being 1 / 3 of the liner volume. Then place the graphite mold into the vacuum hot pressing sintering furnace, turn on the vacuum pump, and evacuate the vacuum degree inside the furnace to 0 MPa. Close and fasten the furnace door. The vacuum hot pressing sintering process is as follows: First, heat it at a heating rate of 10 °C / min to 300 °C. After holding for 30 minutes, apply a pressure of 25 MPa to the silicon carbide-diamond particle aluminum matrix composite powder, then increase the pressure to 50 MPa at a rate of 1 MPa / min, and at the same time continue to heat at a rate of 10 °C / min to 580 °C. After holding for 2 hours, end the heating and cool it with the furnace. When the temperature drops to 400 °C, relieve the pressure applied to the silicon carbide-diamond particle aluminum matrix composite material, and continue to cool with the furnace to room temperature to complete the sintering process. See Figure 6 , there are a small number of pores on the surface of the composite material and at the interface between the irregular silicon carbide particles and the aluminum matrix, while the interface between the diamond particles with a flat surface and the aluminum matrix is tightly bonded and there are no obvious pores. The density of the silicon carbide-diamond particle aluminum matrix composite powder is 98.6%, the thermal conductivity is 319 W / m·K, and the thermal expansion coefficient is 6.3×10 -6 K -1 ~11.9×10 -6 K -1 .

[0080] Example 3

[0081] A) Take raw materials with a purity of over 99.95%: 74.5 g of aluminum powder, 40.4 g of silicon carbide particles, and 35.1 g of diamond particles. The average particle size of the aluminum powder is 25 μm, and the average particle sizes of the silicon carbide particles and diamond particles are 300 μm and 200 μm respectively. The volume ratio of the aluminum powder, silicon carbide particles, and diamond particles is 11:7:3. Put the prepared raw materials into an alumina ball mill tank, add 300 g of alumina ball milling beads, and use anhydrous ethanol as the ball milling medium. The addition amount of anhydrous ethanol is 1 / 2 of the volume of the ball mill tank. Use an alumina ball mill tank with a capacity of 1 L. After loading the raw material powder and anhydrous ethanol, seal it with a sealing bolt. After sealing, close the intake valve on the upper cover of the ball mill tank, open the exhaust valve, and use a small vacuum pump to evacuate the tank to a vacuum with a vacuum degree of -0.1 MPa. Then close the exhaust valve, connect the argon gas pipeline to the intake valve and open it, and fill the tank with high-purity argon until the internal and external air pressures are balanced. Next, open the exhaust valve and keep the argon gas discharging from the exhaust valve for 5 min. Repeat the steps after sealing the ball mill tank twice. Then close the intake valve and exhaust valve of the ball mill tank, and install the ball mill tank on a QXQM-16 all-round planetary ball mill. Set the rotation speed of the ball mill to 100 rpm, and the total operation time of the equipment is 6 h. Stop rotating for 1 min every 5 min of operation, and at the same time change the rotation direction of the ball mill.

[0082] B) After the ball milling is completed, evacuate the glove box to a vacuum degree of -0.1 MPa before using the glove box, and then introduce high-purity argon into the glove box until the air pressure in the glove box is equal to the external air pressure. Repeat this process twice to ensure that the oxygen content in the glove box is maintained at a low level. Open the ball mill tank in the inert gas glove box, and separate the anhydrous ethanol containing the composite powder and the ball milling beads through a sieve. Place the separated anhydrous ethanol slurry in a stainless steel tray and put it into an ultrasonic cleaner in the glove box for 4 h of ultrasonic oscillation dispersion.

[0083] C) Put the dispersed slurry into a small high-temperature vacuum drying oven in the glove box, evacuate the vacuum degree to -0.1 MPa, and set the heating temperature to 50 °C. Restart the mechanical pump every 1 h to restore the vacuum degree to -0.1 MPa, and continue for 6 h. When the vacuum degree no longer drops, introduce high-purity argon into the drying oven to balance the air pressure in the drying oven to the atmospheric pressure, turn off the heating function, take out the composite powder and put it into a vacuum bag, and then the silicon carbide-diamond particle aluminum-based composite powder without agglomeration and with uniform particle size can be obtained.

[0084] D) First, open the intake valve of the vacuum hot-pressing sintering furnace. After the pressure inside the furnace is balanced with the outside, open the furnace door, take out the graphite mold and place it in a stainless steel tray. Take out the mold liner, punch and gasket, and spray boron nitride release agent on the inner wall of the liner and the surfaces of the punch and gasket that come into contact with the silicon carbide-diamond particle aluminum matrix composite powder. After the alcohol in the release agent has completely evaporated, reassemble the liner, punch and gasket into the graphite mold. Take out a small amount of silicon carbide-diamond particle aluminum matrix composite powder from the vacuum bag and fill it into the mold liner of the graphite mold, with the filling amount being 1 / 3 of the liner volume. Then place the graphite mold into the vacuum hot-pressing sintering furnace, turn on the vacuum pump, and evacuate the vacuum degree in the furnace to 0 MPa. Close and fasten the furnace door. The vacuum hot-pressing sintering process is as follows: First, heat it at a heating rate of 10 °C / min to 300 °C, keep it warm for 30 minutes, then apply a pressure of 25 MPa to the silicon carbide-diamond particle aluminum matrix composite material in the graphite mold, and then increase the pressure to 55 MPa at a rate of 1.5 MPa / min, while continuing to heat at a rate of 10 °C / min to 580 °C. After keeping it warm for 2 hours, end the heating and cool it with the furnace. When the temperature drops to 400 °C, release the pressure and continue to cool with the furnace to room temperature to complete the sintering process. See Figure 7 , the surface of the composite material is flat and clean, without obvious holes. The silicon carbide diamond particles are evenly distributed in the aluminum matrix. The density of the silicon carbide-diamond particle aluminum matrix composite material is 99.4%, the thermal conductivity is 368 W / m·K, and the thermal expansion coefficient is 5.5×10 - 6 K -1 ~10.7×10 -6 K -1 .

[0085] Example 4

[0086] A) Take raw materials with a purity of over 99.95%: 74.5 g of aluminum powder, 40.4 g of silicon carbide particles, and 35.1 g of diamond particles. The average particle size of the aluminum powder is 25 μm, and the average particle sizes of the silicon carbide particles and diamond particles are 300 μm and 200 μm respectively. The volume ratio of the aluminum powder, silicon carbide particles, and diamond particles is 11:7:3. Put the prepared raw materials into an alumina ball milling tank, add 300 g of alumina milling beads, and use absolute ethanol as the ball milling medium. The addition amount of absolute ethanol is 1 / 2 of the volume of the ball milling tank. Use an alumina ball milling tank with a capacity of 1 L. After loading the raw material powder and absolute ethanol, seal it with a sealing bolt. After sealing, close the intake valve on the upper cover of the ball milling tank, open the exhaust valve, and use a small vacuum pump to evacuate the tank to a vacuum with a vacuum degree of -0.1 MPa. Then close the exhaust valve, connect the argon gas pipeline to the intake valve and open it, and fill the tank with high-purity argon until the internal and external air pressures are balanced. Next, open the exhaust valve and keep the argon gas discharging from the exhaust valve for 5 min. Repeat the steps after sealing the ball milling tank twice. Then close the intake valve and exhaust valve of the ball milling tank, and install the ball milling tank on a QXQM-16 all-round planetary ball mill. Set the rotation speed of the ball mill to 100 rpm, and the total operation time of the equipment is 6 h. Stop rotating for 1 min every 5 min of operation, and at the same time change the rotation direction of the ball mill.

[0087] B) After ball milling, evacuate the glove box to a vacuum degree of -0.1 MPa before using the glove box, and then introduce high-purity argon into the glove box until the air pressure in the glove box is equal to the external air pressure. Repeat this process twice to ensure that the oxygen content in the glove box is maintained at a low level. Open the ball milling tank in the inert gas glove box, and separate the absolute ethanol containing the composite powder and the milling beads through a sieve. Place the separated absolute ethanol slurry in a stainless steel tray and put it into an ultrasonic cleaner in the glove box for 4 h of ultrasonic oscillation dispersion.

[0088] C) Put the dispersed slurry into a small high-temperature vacuum drying oven in the glove box, evacuate the vacuum degree to -0.1 MPa, and set the heating temperature to 50 °C. Restart the mechanical pump every 1 h to restore the vacuum degree to -0.1 MPa, and continue for 6 h. When the vacuum degree no longer drops, introduce high-purity argon into the drying oven to balance the air pressure in the drying oven to atmospheric pressure, turn off the heating function, take out the composite powder and put it into a vacuum bag, and then silicon carbide-diamond particle aluminum-based composite powder without agglomeration and with uniform particle size can be obtained.

[0089] D) First, open the intake valve of the vacuum hot-pressing sintering furnace. After the pressure inside the furnace is balanced with the outside, open the furnace door, take out the graphite mold and place it in a stainless steel tray. Take out the mold liner, punch, and gasket, and spray boron nitride release agent on the inner wall of the liner and the surfaces of the punch and gasket that come into contact with the silicon carbide-diamond particle aluminum matrix composite powder. After the alcohol in the release agent has completely evaporated, reassemble the liner, punch, and gasket into the graphite mold. Take out a small amount of silicon carbide-diamond particle aluminum matrix composite powder from the vacuum bag and fill it into the mold liner of the graphite mold, with the filling amount being 1 / 3 of the liner volume. Then place the graphite mold into the vacuum hot-pressing sintering furnace, turn on the vacuum pump, and evacuate the vacuum in the furnace to 0 MPa. Close and fasten the furnace door. The vacuum hot-pressing sintering process is as follows: First, heat it at a heating rate of 10 °C / min to 300 °C. After holding for 30 minutes, apply a pressure of 25 MPa to the silicon carbide-diamond particle aluminum matrix composite material in the graphite mold. Then increase the pressure to 55 MPa at a rate of 1.5 MPa / min, and at the same time continue to heat at a rate of 10 °C / min to 580 °C. After holding for 3 hours, end the heating and cool it in the furnace. When the temperature drops to 400 °C, relieve the pressure and continue to cool in the furnace to room temperature to complete the sintering process. See Figure 8 , the surface of the composite material is smooth and clean, with only a small number of micro-pores. The silicon carbide and diamond particles are evenly distributed in the aluminum matrix. The density of the silicon carbide-diamond particle aluminum matrix composite material reaches 99.1%, the thermal conductivity is 342 W / m·K, and the thermal expansion coefficient varies from 5.8×10 -6 K -1 to 11.3×10 -6 K -1 .

[0090] Example 5

[0091] A) Take raw materials with a purity of over 99.95%: 74.5 g of aluminum powder, 40.4 g of silicon carbide particles, and 35.1 g of diamond particles. The average particle size of the aluminum powder is 25 μm, and the average particle sizes of the silicon carbide particles and diamond particles are 300 μm and 200 μm respectively. The volume ratio of the aluminum powder, silicon carbide particles, and diamond particles is 11:7:3. Put the prepared raw materials into an alumina ball mill tank, add 300 g of alumina ball mill beads, and use anhydrous ethanol as the ball milling medium. The addition amount of anhydrous ethanol is 1 / 2 of the volume of the ball mill tank. Use an alumina ball mill tank with a capacity of 1 L. After loading the raw material powder and anhydrous ethanol, seal it with a sealing bolt. After sealing, close the intake valve on the upper cover of the ball mill tank, open the exhaust valve, and use a small vacuum pump to evacuate the tank to a vacuum with a vacuum degree of -0.1 MPa. Then close the exhaust valve, connect the argon gas pipeline to the intake valve and open it, and fill the tank with high-purity argon until the internal and external air pressures are balanced. Next, open the exhaust valve and keep the argon gas discharging from the exhaust valve for 5 min. Repeat the steps after sealing the ball mill tank twice. Then close the intake valve and exhaust valve of the ball mill tank, and install the ball mill tank on a QXQM-16 all-round planetary ball mill. Set the rotation speed of the ball mill to 100 rpm, and the total operation time of the equipment is 6 h. Stop rotating for 1 min every 5 min of operation, and at the same time change the rotation direction of the ball mill.

[0092] B) After ball milling, evacuate the glove box to a vacuum degree of -0.1 MPa before using the glove box, and then introduce high-purity argon into the glove box until the air pressure in the glove box is equal to the external air pressure. Repeat this process twice to ensure that the oxygen content in the glove box is maintained at a low level. Open the ball mill tank in the inert gas glove box, and separate the anhydrous ethanol containing the composite powder and the ball mill beads through a sieve. Place the separated anhydrous ethanol slurry in a stainless steel tray and put it into an ultrasonic cleaner in the glove box for 4 h of ultrasonic oscillation dispersion.

[0093] C) Put the dispersed slurry into a small high-temperature vacuum drying oven in the glove box, evacuate the vacuum degree to -0.1 MPa, and set the heating temperature to 50 °C. Restart the mechanical pump every 1 h to restore the vacuum degree to -0.1 MPa, and continue for 6 h. When the vacuum degree no longer drops, introduce high-purity argon into the drying oven to balance the air pressure in the drying oven to the atmospheric pressure, turn off the heating function, take out the composite powder and put it into a vacuum bag, and then a silicon carbide-diamond particle aluminum-based composite powder without agglomeration and with uniform particle size can be obtained.

[0094] D) First, open the intake valve of the vacuum hot pressing sintering furnace. After the pressure inside the furnace is balanced with the outside, open the furnace door, take out the graphite mold and place it in a stainless steel tray. Take out the mold lining, punch and gasket, and spray boron nitride release agent on the inner wall of the lining and the surfaces of the punch and gasket that come into contact with the silicon carbide-diamond particle aluminum matrix composite powder. After the alcohol in the release agent has completely evaporated, reassemble the lining, punch and gasket into the graphite mold. Take out a small amount of silicon carbide-diamond particle aluminum matrix composite powder from the vacuum bag and fill it into the mold lining of the graphite mold. The filling amount is 1 / 3 of the volume of the lining. Then place the graphite mold into the vacuum hot pressing sintering furnace, turn on the vacuum pump, and evacuate the vacuum degree inside the furnace to 0 MPa. Close and fasten the furnace door. The vacuum hot pressing sintering process is as follows: First, heat it at a heating rate of 10 °C / min to 300 °C, keep it warm for 30 minutes, then apply a pressure of 25 MPa to the silicon carbide-diamond particle aluminum matrix composite material in the graphite mold, and then increase the pressure to 55 MPa at a rate of 1.5 MPa / min, while continuing to heat at a rate of 10 °C / min to 570 °C. After keeping it warm for 2 hours, end the heating and cool it with the furnace. When the temperature drops to 400 °C, relieve the pressure and continue to cool with the furnace to room temperature to complete the sintering process. See Figure 9 , the surface of the composite material is relatively rough and there are no obvious pores. The silicon carbide diamond particles are evenly distributed in the aluminum matrix. The density of the silicon carbide-diamond particle aluminum matrix composite material is 98.8%, the thermal conductivity is 328 W / m·K, and the thermal expansion coefficient is 6.0×10 - 6 K -1 ~11.6×10 -6 K -1 .

[0095] The above-described embodiments of the present invention do not constitute a limitation to the protection scope of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A preparation method of a silicon carbide-diamond particle aluminum matrix composite material, characterized in that, Including the steps: (X1) Wet ball milling, dispersing, and drying aluminum powder, silicon carbide particles, and diamond particles with preset volume fractions respectively to obtain silicon carbide-diamond particle aluminum matrix composite powder. The wet ball milling specifically includes alternately rotating the ball mill clockwise and counterclockwise and stopping during the alternation. (X2) Vacuum sintering the silicon carbide-diamond particle aluminum matrix composite powder obtained in step (X1), and performing gradient heating during the vacuum sintering to obtain a silicon carbide-diamond particle aluminum matrix composite material.

2. The preparation method according to claim 1, characterized in that, Step (X2) specifically includes: (X21) First-stage heating: Raise the temperature to 300°C - 400°C at a heating rate of 6°C / min - 10°C / min. (X22) First-stage heat preservation: 10 min - 30 min. (X23) Second-stage heating: Continue to raise the temperature to 500°C - 600°C at a rate of 8°C / min - 10°C / min. (X24) Second-stage heat preservation: Keep the temperature for 1 h - 3 h. (X25) End the heating and perform cooling.

3. The preparation method according to claim 2, characterized in that, Step (X2) also includes: In step (X23), apply a pressure of 20 MPa - 25 MPa to the silicon carbide-diamond particle aluminum matrix composite powder, and during the heating process, increase the pressure applied to the silicon carbide-diamond particle aluminum matrix composite powder from 1 MPa / min - 1.5 MPa / min to 50 MPa - 55 MPa. In step (X25), when cooling to a temperature of 400°C, stop applying pressure to the silicon carbide-diamond particle aluminum matrix composite powder and then continue to cool.

4. The preparation method according to claim 1, characterized in that, Step (X1) specifically includes: (X11) Wet ball mill aluminum powder, silicon carbide particles, and diamond particles with preset volume fraction ratios respectively under a protective atmosphere to obtain composite powder. The wet ball milling specifically includes alternately rotating the ball mill clockwise and counterclockwise and stopping during the alternation. (X12) Place the composite powder obtained in step (X11) in a protective atmosphere for ultrasonic dispersion to obtain a dispersed composite powder. (X13) Place the dispersed composite powder obtained in step (X12) in a vacuum environment for drying treatment to obtain the silicon carbide-diamond particle aluminum matrix composite powder.

5. The preparation method according to claim 4, characterized in that, In step (X11), the duration of each clockwise rotation ball milling and each counterclockwise rotation ball milling is 3 min - 5 min respectively; the stopping time during the alternation is 1 min - 2 min, and the total time of the wet ball milling is 6 h.

6. The preparation method according to claim 4, wherein In step (X11), the average particle size of the aluminum powder is 25 μm - 30 μm; the average particle size of the silicon carbide particles is 250 μm - 300 μm; the average particle size of the diamond particles is 200 μm - 250 μm.

7. The preparation method according to claim 4, characterized in that, The preset volume fraction ratio of the aluminum powder, the silicon carbide particles, and the diamond particles is 11:5 - 7:2 - 4.

8. The preparation method according to claim 4, characterized in that, In the step (X13), the initial temperature in the drying treatment is 30°C to 40°C, and the temperature is increased at a rate of 5°C to 8°C every 2h to 4h until the temperature reaches 50°C to 60°C, and then dried for 24h to 48h.

9. A silicon carbide-diamond particle aluminum matrix composite, characterized in that, It includes the silicon carbide-diamond particle aluminum matrix composite material prepared by using the preparation method of the silicon carbide-diamond particle aluminum matrix composite material according to any one of claims 1 to 8.

10. The silicon carbide-diamond particle aluminum matrix composite material according to claim 9, characterized in that, The density of the silicon carbide-diamond particle aluminum matrix composite is greater than or equal to 98.5%, the thermal conductivity is 270 W / m·K to 370 W / m·K, and the coefficient of thermal expansion is 5.5×10 －6 ·K －1 ~12.0×10 －6 ·K －1 .

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