Aluminum-silicon-based composite material and preparation method thereof

Abstract

The invention provides an aluminum-silicon-based composite material and a preparation method thereof, and particularly relates to the technical field of metal-based composite materials. In an inert gas protection environment, aluminum-silicon alloy, bismuth powder, grinding balls and absolute ethyl alcohol are mixed for primary ball milling, then modified molybdenum disulfide is added for secondary ball milling, and after secondary ball milling is finished, washing and drying are conducted to obtain mixed powder; and pre-pressing the mixed powder in a mold, putting the pre-pressed mixed powder in FHP rapid sintering equipment, clamping graphite electrode pressure heads on two sides of the mold, electrifying direct current, pressurizing, heating, and keeping the temperature for 15-30 minutes to obtain the aluminum-silicon-based composite material. The modified molybdenum disulfide can effectively solve the problem that the thermal conductivity is reduced due to the fact that the silicon content in the aluminum-silicon-based composite material is too high, and the aluminum-silicon-based composite material prepared through the method is excellent in performance, high in density, high in thermal conductivity and capable of meeting the requirement of contemporary packaging materials for high heat dissipation.

Description

Technical Field

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

[0002] At present, the density of the sintered aluminum-silicon-based composite materials is not enough, which leads to insufficient strength, rigidity and corrosion resistance of electronic packaging materials, poor durability of electronic packaging material shells, and easy damage to chips; at the same time, there will be pores at the grain boundaries inside the non-dense products, which seriously affect the thermal conductivity of the aluminum-silicon-based composite materials. The large amount of heat generated during chip operation cannot be discharged in time, affecting the normal operation of the electronic chip or even damaging the electronic chip. In addition, the traditional hot pressing process has a slow heating rate, a long product preparation time, and the product performance is not enough to meet the strict use requirements. The low production efficiency cannot meet the current electronic industry, especially the military industry, for the huge market demand for aluminum-silicon-based composite electronic packaging materials. Therefore, there is a need for a device that can quickly produce aluminum-silicon-based composite materials with excellent performance to solve this problem.

[0003] Silicon has good oxidation resistance and thermal creep resistance. Aluminum-silicon based composites with high silicon content can maintain good mechanical properties and stability in high temperature environments. This property enables aluminum-silicon based composites to perform well under high temperature working conditions. However, the increase in silicon content will affect the thermal conductivity of aluminum-silicon based composites. The thermal conductivity of silicon is lower than that of aluminum, and the presence of silicon in the aluminum matrix will scatter the free electrons that transfer heat energy. The thermal conductivity of aluminum-silicon based composites decreases with the increase of silicon content.

[0004] Patent CN108941197B provides a method for preparing a high thermal conductivity aluminum-silicon alloy sheet. The invention uses a rolling method to cause plastic deformation of the aluminum-silicon alloy, thereby achieving the purpose of improving the thermal conductivity of the aluminum-silicon alloy. Although the aluminum-silicon alloy sheet prepared by the invention has good mechanical properties and thermal conductivity, it does not improve the density of the aluminum-silicon alloy. Patent CN111636006B provides an aluminum-silicon alloy graphite composite thermal conductive material and its preparation and application. The aluminum-silicon alloy graphite composite thermal conductive material is prepared by compounding flaky graphite sheets with aluminum-silicon alloy powder. Due to the crystal structure of graphite, the flaky graphite sheets have poor thermal conductivity in the direction perpendicular to the plane, resulting in additional resistance during heat transfer, thereby reducing the overall thermal conductivity efficiency.

[0005] Therefore, providing an aluminum-silicon-based composite material that reduces the low density effect brought by silicon and thereby achieves high thermal conductivity is an issue that needs to be urgently addressed in the art. Summary of the invention

[0006] In order to solve the problems of low density and poor thermal conductivity of aluminum-silicon based composite materials in the prior art, the present invention provides an aluminum-silicon based composite material and a preparation method thereof.

[0007] To achieve the above object, the present invention adopts the following technical solution:

[0008] A method for preparing an aluminum-silicon based composite material, the preparation method comprising the following steps:

[0009] In an inert gas protection environment, aluminum silicon alloy, bismuth powder, grinding balls and anhydrous ethanol are mixed and ball-milled once, and then modified molybdenum disulfide is added for secondary ball-milling. After the secondary ball-milling, the mixed powder is washed and dried to obtain a mixed powder; the mixed powder is pre-pressed in a mold and then placed in a FHP rapid sintering device, a graphite electrode pressure head is placed on both sides of the mold, a direct current is passed, and pressure is heated and then kept warm for 15 to 30 minutes to obtain the aluminum silicon-based composite material.

[0010] Furthermore, the preparation of the modified molybdenum disulfide comprises the following steps:

[0011] Ammonium molybdate tetrahydrate and thiourea are dispersed in deionized water, subjected to ultrasonic treatment for 10 to 20 minutes, reacted in an environment of 200 to 220° C. for 8 to 10 hours, and centrifuged and washed to obtain flaky molybdenum disulfide; flaky molybdenum disulfide is dispersed in a mixed solvent, aluminum chloride hexahydrate and ammonium bicarbonate are added, the pH value is adjusted to 8 to 9, stirred for 30 to 60 minutes, and then a surfactant is added, stirred for reaction for 2 to 3 hours, and then allowed to stand for 12 to 24 hours, washed and dried, and then calcined in an environment of 700 to 800° C. for 3 to 6 hours to obtain the modified molybdenum disulfide.

[0012] Furthermore, the weight ratio of the ammonium molybdate tetrahydrate to thiourea is 1:1-2.

[0013] Furthermore, the mixed solvent is prepared by mixing deionized water and anhydrous ethanol in a weight ratio of 1:1.5.

[0014] Furthermore, the weight ratio of the flaky molybdenum disulfide, aluminum chloride hexahydrate and ammonium bicarbonate is 1:1.0-1.5:2.0-2.5.

[0015] Furthermore, the surfactant is PEG4000, PEG5000 or PEG6000.

[0016] Furthermore, the weight ratio of the aluminum chloride hexahydrate to the surfactant is 1:10-20.

[0017] Furthermore, the aluminum-silicon alloy includes Al-Si27, Al-Si40, Al-Si50 or Al-Si70.

[0018] Furthermore, the amount of the bismuth powder used is 1-2% of the weight of the aluminum-silicon alloy.

[0019] Furthermore, the grinding balls are zirconia balls, and the weight ratio of the grinding balls to the aluminum silicon alloy is 5:1.

[0020] Furthermore, the amount of anhydrous ethanol used is 1.5 times the total weight of the grinding balls and the silicon-aluminum alloy.

[0021] Furthermore, the grinding speed of the first ball milling is 250-300 rpm and the grinding time is 5-8 hours.

[0022] Furthermore, the amount of the modified molybdenum disulfide is 1% to 5% of the weight of the aluminum silicon alloy.

[0023] Furthermore, the grinding speed of the secondary ball milling is 150-200 rpm and the grinding time is 2-3 hours.

[0024] Furthermore, the mold is a cemented carbide mold or a graphite mold.

[0025] Furthermore, the specification of the mold is φ50mm.

[0026] Furthermore, the pre-pressing pressure is 150-300 MPa and the time is 10-30 min.

[0027] Furthermore, the pressurization and heating are pressurization to 50-100 MPa and heating to 800-900°C.

[0028] Furthermore, the inert gas is nitrogen or argon.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) Alumina is precipitated on the surface of flaky molybdenum disulfide by a precipitation method. The flaky molybdenum disulfide restricts the aluminum oxide to its lamellae, making up for the shortcoming of poor thermal conductivity between its lamellae. Alumina particles fill the gaps between the flaky molybdenum disulfide, reduce the air layer at the interface, and good interface contact enhances the original heat conduction path of molybdenum disulfide, forming an efficient heat conduction network. The modified molybdenum disulfide provided by the present invention can effectively solve the problem of decreased thermal conductivity caused by excessive silicon content in aluminum-silicon based composite materials.

[0031] (2) The present invention improves the performance of the aluminum-silicon based composite material by introducing bismuth powder with a low melting point. During the temperature rising sintering process, the bismuth powder melts to form a liquid phase which diffuses into the aluminum-silicon alloy with a higher melting point which is still in the solid phase, thereby generating a wetting effect between the surfaces of the two components of the aluminum-silicon alloy. The liquid phase wets the surrounding high melting point metal or alloy. The capillary force generated during this period causes the atomic particles to rearrange and densify, thereby promoting the rapid sintering and densification of the material.

[0032] (3) The present invention adopts rapid hot pressing sintering technology and introduces direct current electric field assisted sintering during the sintering process. The target sintering temperature, direct current electric field assistance, and pressure jointly promote the microstructure of the aluminum-silicon based composite material to be arranged in a more compact manner. The densification degree of the aluminum-silicon based composite material is higher. A shorter sintering time can form a fine-grained structure, which significantly improves the mechanical properties. The direct current electric field can produce flash burning, and the performance of the aluminum-silicon based composite material is significantly improved. The uniform and dense microstructure and good interface bonding can bring about excellent thermal conductivity.

[0033] (4) The preparation method adopted by the present invention uses a DC power supply to form a DC electric field to assist sintering, which can greatly reduce the production cost compared with a pulse power supply; at the same time, it can also reduce the densification sintering temperature of the aluminum silicon-based composite material, and the performance parameters of the aluminum silicon-based composite material are optimized. The entire heating sintering and cooling process is relatively short, which can greatly improve the production efficiency of the aluminum silicon-based composite material. Therefore, the aluminum silicon-based composite material after rapid hot pressing sintering and formula optimization has obvious advantages in the field of large-scale industrial application.

[0034] (5) In the present invention, the sintering process of the aluminum-silicon based composite material is optimized by the combined effects of target sintering temperature, DC electric field assistance and pressure. The transient liquid phase sintering introduced in the formula of the aluminum-silicon based composite material of the present invention can synergistically promote sintering. The aluminum-silicon based composite material prepared by the present invention has excellent performance and can meet the high heat dissipation requirements of contemporary packaging materials. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be clearly and completely described below through the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0036] Unless otherwise specified, the raw materials and reagents used in the present invention are commercially available or can be prepared by known methods.

[0037] Preparation Example 1:

[0038] The preparation of the mixed solvent comprises the following steps:

[0039] 100 parts by weight of deionized water and 150 parts by weight of anhydrous ethanol were mixed and stirred for 5 minutes to prepare a mixed solvent.

[0040] Preparation Example 2:

[0041] The preparation comprises the following steps:

[0042] 10 parts by weight of ammonium molybdate tetrahydrate and 10 parts by weight of thiourea were dispersed in 100 parts by weight of deionized water, and after ultrasonication for 10 minutes, they were transferred to a Teflon-lined stainless steel autoclave and reacted at 200°C for 8 hours. After the reaction, the mixture was centrifuged at 12000 rpm for 30 minutes, and washed three times with deionized water to obtain flaky molybdenum disulfide. 10 parts by weight of flaky molybdenum disulfide was dispersed in 100 parts by weight of the mixed solvent prepared in Preparation Example 1, 10 parts by weight of aluminum chloride hexahydrate and 20 parts by weight of ammonium bicarbonate were added, the pH was adjusted to 8, stirred for 30 minutes, and then 100 parts by weight of PEG4000 were added. The mixture was stirred for 2 hours, then allowed to stand for 12 hours, washed and dried, and kept warm at 700°C for 3 hours to obtain modified molybdenum disulfide.

[0043] Preparation Example 3:

[0044] The preparation of modified molybdenum disulfide comprises the following steps:

[0045] 10 parts by weight of ammonium molybdate tetrahydrate and 13 parts by weight of thiourea were dispersed in 100 parts by weight of deionized water, and after ultrasonic treatment for 15 minutes, the mixture was transferred to a Teflon-lined stainless steel autoclave and reacted for 9 hours in a 210°C environment. After the reaction, the mixture was centrifuged at a speed of 12000 rpm for 30 minutes, and washed three times with deionized water to obtain flaky molybdenum disulfide. 10 parts by weight of flaky molybdenum disulfide was dispersed in 100 parts by weight of the mixed solvent prepared in Preparation Example 1, 12 parts by weight of aluminum chloride hexahydrate and 21 parts by weight of ammonium bicarbonate were added, the pH was adjusted to 8.5, stirred for 40 minutes, and then 15 parts by weight of PEG5000 were added. The mixture was stirred for 2.5 hours and then allowed to stand for 16 hours. After washing and drying, the mixture was kept warm at 750°C for 4 hours to obtain modified molybdenum disulfide.

[0046] Preparation Example 4:

[0047] The preparation of modified molybdenum disulfide comprises the following steps:

[0048] 10 parts by weight of ammonium molybdate tetrahydrate and 16 parts by weight of thiourea were dispersed in 100 parts by weight of deionized water, and after ultrasonic treatment for 15 minutes, the mixture was transferred to a Teflon-lined stainless steel autoclave and reacted for 9 hours in a 210°C environment. After the reaction, the mixture was centrifuged at a speed of 12000 rpm for 30 minutes, and washed three times with deionized water to obtain flaky molybdenum disulfide. 10 parts by weight of flaky molybdenum disulfide was dispersed in 100 parts by weight of the mixed solvent prepared in Preparation Example 1, 14 parts by weight of aluminum chloride hexahydrate and 23 parts by weight of ammonium bicarbonate were added, the pH was adjusted to 8, stirred for 30 minutes, and then 15 parts by weight of PEG6000 were added. The mixture was stirred for 2 hours and then allowed to stand for 20 hours. After washing and drying, the mixture was kept warm at 780°C for 5 hours to obtain modified molybdenum disulfide.

[0049] Preparation Example 5:

[0050] The preparation of modified molybdenum disulfide comprises the following steps:

[0051] 10 parts by weight of ammonium molybdate tetrahydrate and 20 parts by weight of thiourea were dispersed in 100 parts by weight of deionized water, and after ultrasonic treatment for 20 minutes, the mixture was transferred to a Teflon-lined stainless steel autoclave and reacted for 10 hours in a 220°C environment. After the reaction, the mixture was centrifuged at a speed of 12000 rpm for 30 minutes, and washed three times with deionized water to obtain flaky molybdenum disulfide. 10 parts by weight of flaky molybdenum disulfide was dispersed in 100 parts by weight of the mixed solvent prepared in Preparation Example 1, 15 parts by weight of aluminum chloride hexahydrate and 25 parts by weight of ammonium bicarbonate were added, the pH was adjusted to 9, stirred for 60 minutes, and then 50 parts by weight of PEG6000 were added. The mixture was stirred for 3 hours, then allowed to stand for 24 hours, washed and dried, and kept warm for 6 hours in a 800°C environment to obtain modified molybdenum disulfide.

[0052] Embodiment 1:

[0053] A method for preparing an aluminum-silicon based composite material comprises the following steps:

[0054] In a nitrogen protection environment, 10 parts by weight of Al-Si27, 0.1 parts by weight of bismuth powder, 50 parts by weight of zirconium oxide balls and 90 parts by weight of anhydrous ethanol are ground at a speed of 250 rpm for 5 hours for a first ball milling, and then 0.1 parts by weight of modified molybdenum disulfide prepared in Preparation 2 is added and ground at a speed of 150 rpm for 2 hours for a second ball milling, and after the second ball milling, the mixture is washed with anhydrous ethanol and dried at 60°C for 2 hours to obtain a mixed powder; the mixed powder is placed in a φ50 mm cemented carbide mold and pre-pressed at a pressure of 150 MPa for 30 minutes, and after the pre-pressing, the cemented carbide mold containing the mixed powder is placed in a sintering cavity of a FHP rapid sintering equipment, and a graphite electrode pressure head is applied to both sides of the mold, and a direct current is passed to generate a direct current electric field, and at the same time, the vacuum is evacuated to 0.05 Pa in a 23°C environment, and then the temperature is increased to 800°C at a heating rate of 100°C / min, and the aluminum silicon-based composite material is obtained by keeping the temperature at a pressure of 50 MPa for 15 minutes.

[0055] Embodiment 2:

[0056] A method for preparing an aluminum-silicon based composite material comprises the following steps:

[0057] In an argon protection environment, 10 parts by weight of Al-Si40, 0.15 parts by weight of bismuth powder, 50 parts by weight of zirconium oxide balls and 90 parts by weight of anhydrous ethanol were ground at a speed of 280 rpm for 6 hours for a first ball milling, and then 0.3 parts by weight of modified molybdenum disulfide prepared in Preparation 3 was added and ground at a speed of 170 rpm for 2.5 hours for a second ball milling. After the second ball milling, the mixture was washed with anhydrous ethanol and dried at 70°C for 2.5 hours to obtain a mixed powder. The mixed powder was placed in a φ50m The graphite mold was pre-pressed at a pressure of 200 MPa for 20 minutes. After the pre-pressing, the graphite mold containing the mixed powder was placed in the sintering chamber of the FHP rapid sintering equipment. The graphite electrode pressure heads were attached to both sides of the mold. Direct current was passed to generate a direct current electric field. At the same time, the vacuum degree was evacuated to 0.01 Pa in an environment of 24°C. The temperature was then raised to 850°C at a heating rate of 100°C / min and kept warm at a pressure of 80 MPa for 20 minutes to obtain an aluminum-silicon based composite material.

[0058] Embodiment 3:

[0059] A method for preparing an aluminum-silicon based composite material comprises the following steps:

[0060] In an argon protection environment, 10 parts by weight of Al-Si50, 0.15 parts by weight of bismuth powder, 50 parts by weight of zirconium oxide balls and 90 parts by weight of anhydrous ethanol were ground at a speed of 280 rpm for 7 hours for a first ball milling, and then 0.4 parts by weight of the modified molybdenum disulfide prepared in Preparation 4 was added and ground at a speed of 180 rpm for 2 hours for a second ball milling. After the second ball milling, the mixture was washed with anhydrous ethanol and dried at 75°C for 2.5 hours to obtain a mixed powder; the mixed powder was placed on a φ50 mm hard The alloy mold was pre-pressed at a pressure of 250 MPa for 25 minutes. After the pre-pressing, the cemented carbide mold filled with the mixed powder was placed in the sintering chamber of the FHP rapid sintering equipment. The graphite electrode press heads were attached to both sides of the mold. Direct current was passed to generate a direct current electric field. At the same time, the vacuum degree was evacuated to 0.03 Pa in an environment of 25°C. The temperature was then heated to 870°C at a heating rate of 100°C / min and kept warm at a pressure of 100 MPa for 25 minutes to obtain an aluminum-silicon based composite material.

[0061] Embodiment 4:

[0062] A method for preparing an aluminum-silicon based composite material comprises the following steps:

[0063] In a nitrogen protection environment, 10 parts by weight of Al-Si70, 0.3 parts by weight of bismuth powder, 50 parts by weight of zirconium oxide balls and 90 parts by weight of anhydrous ethanol were ground at a speed of 300 rpm for 8 hours for a primary ball milling, and then 0.5 parts by weight of the modified molybdenum disulfide prepared in Preparation 5 was added and ground at a speed of 200 rpm for 3 hours for a secondary ball milling, and after the secondary ball milling, the mixture was washed with anhydrous ethanol and dried in an environment of 80°C for 3 hours to obtain a mixed powder; the mixed powder was placed in a φ50mm graphite mold and pre-pressed at a pressure of 300MPa for 30 minutes, and after the pre-pressing, the graphite mold containing the mixed powder was placed in a sintering cavity of a FHP rapid sintering equipment, and a graphite electrode pressure head was applied to both sides of the mold, and a direct current was passed to generate a direct current electric field. At the same time, the vacuum degree was evacuated to 0.05Pa in an environment of 25°C, and then the temperature was increased to 900°C at a heating rate of 100°C / min, and the aluminum silicon-based composite material was obtained by keeping the temperature at a pressure of 100Mpa for 30 minutes.

[0064] Comparative Example 1:

[0065] A method for preparing an aluminum-silicon based composite material comprises the following steps:

[0066] In a nitrogen protection environment, 10 parts by weight of Al-Si70, 0.3 parts by weight of bismuth powder, 50 parts by weight of zirconium oxide balls and 90 parts by weight of anhydrous ethanol are ball-milled at a speed of 300 rpm for 8 hours, washed with anhydrous ethanol after the ball milling, and dried in an environment of 80°C for 3 hours to obtain a mixed powder; the mixed powder is placed in a φ50mm graphite mold and pre-pressed at a pressure of 300MPa for 30 minutes, and after the pre-pressing, the graphite mold containing the mixed powder is placed in a sintering cavity of a FHP rapid sintering equipment, and graphite electrode pressure heads are applied to both sides of the mold, and direct current is passed to generate a direct current electric field, and at the same time, the vacuum degree is evacuated to 0.05Pa in an environment of 25°C, and then the temperature is increased to 900°C at a heating rate of 100°C / min, and the temperature is kept at a pressure of 100Mpa for 30 minutes to obtain an aluminum-silicon-based composite material.

[0067] Comparative Example 2:

[0068] A method for preparing an aluminum-silicon based composite material comprises the following steps:

[0069] In a nitrogen protection environment, 10 parts by weight of Al-Si70, 50 parts by weight of zirconia balls and 90 parts by weight of anhydrous ethanol were ground at a speed of 300 rpm for 8 hours for a primary ball milling, and then 0.5 parts by weight of the modified molybdenum disulfide prepared in Preparation 5 was added and ground at a speed of 200 rpm for 3 hours for a secondary ball milling. After the secondary ball milling, the mixture was washed with anhydrous ethanol and dried at 80°C for 3 hours to obtain a mixed powder. The mixed powder was placed in a φ50 mm graphite mold and pre-pressed at a pressure of 300 MPa for 30 minutes. After the pre-pressing, the graphite mold containing the mixed powder was placed in a sintering chamber of a FHP rapid sintering equipment, and a graphite electrode pressure head was applied to both sides of the mold. While a direct current was passed to generate a direct current electric field, the vacuum was evacuated to 0.05 Pa in a 25°C environment, and then the temperature was increased to 900°C at a heating rate of 100°C / min, and the mixture was kept warm at a pressure of 100 MPa for 30 minutes to obtain an aluminum-silicon-based composite material.

[0070] Comparative Example 3:

[0071] A method for preparing an aluminum-silicon based composite material comprises the following steps:

[0072] In a nitrogen protective environment, 10 parts by weight of Al-Si70, 0.3 parts by weight of bismuth powder, 50 parts by weight of zirconium oxide balls and 90 parts by weight of anhydrous ethanol are ground at a speed of 300 rpm for 8 hours for a first ball milling, and then 0.5 parts by weight of modified molybdenum disulfide prepared in Preparation 5 is added and ground at a speed of 200 rpm for 3 hours for a second ball milling. After the second ball milling, the mixed powder is washed with anhydrous ethanol and dried at 80°C for 3 hours to obtain a mixed powder. In a nitrogen protective environment, the mixed powder is placed in a φ50 mm graphite mold and pre-pressed at a pressure of 300 MPa for 30 minutes. After the pre-pressing, the mixed powder is kept at 900°C for 2 hours to obtain an aluminum-silicon based composite material.

[0073] Comparative Example 4:

[0074] A method for preparing an aluminum-silicon based composite material comprises the following steps:

[0075] In a nitrogen protection environment, 10 parts by weight of Al-Si70, 0.3 parts by weight of bismuth powder, 50 parts by weight of zirconium oxide balls, 0.5 parts by weight of modified molybdenum disulfide prepared in Preparation 5 and 90 parts by weight of anhydrous ethanol are ball-milled at a speed of 300 rpm for 8 hours, washed with anhydrous ethanol after the ball milling, and dried in an environment of 80°C for 3 hours to obtain a mixed powder; the mixed powder is placed in a φ50 mm graphite mold and pre-pressed at a pressure of 300 MPa for 30 minutes, and after the pre-pressing, the graphite mold containing the mixed powder is placed in a sintering chamber of an FHP rapid sintering equipment, a graphite electrode pressure head is applied to both sides of the mold, a direct current is passed to generate a direct current electric field, and at the same time, the vacuum degree is evacuated to 0.05 Pa in an environment of 25°C, and then the temperature is increased to 900°C at a heating rate of 100°C / min, and the aluminum silicon-based composite material is obtained by keeping the temperature at a pressure of 100 MPa for 30 minutes.

[0076] Test Example 1: Thermal conductivity test

[0077] The thermal conductivity of the aluminum-silicon based composite materials obtained in Examples 1 to 4 and Comparative Examples 1 to 4 was tested. The test results are shown in Table 1.

[0078] Table 1. Thermal conductivity test data of aluminum-silicon based composite materials obtained in Examples 1 to 4 and Comparative Examples 1 to 4

[0079]

[0080]

[0081] It can be observed in Table 1 that the aluminum-silicon-based composite materials prepared in Examples 1 to 4 have good thermal conductivity compared with the aluminum-silicon-based composite materials prepared in Comparative Examples 1 to 4. This is attributed to the addition of bismuth powder and modified molybdenum disulfide, which effectively compensates for the decrease in thermal conductivity of the aluminum-silicon-based composite materials due to the increase in silicon content. The aluminum oxide particles and flaky molybdenum disulfide in the modified molybdenum disulfide constitute an efficient thermal conductive network, which helps to quickly transfer heat within the aluminum-silicon-based composite material. The high-speed rotation and long-term grinding of the modified molybdenum disulfide in Comparative Example 4 changed the original structure of the modified molybdenum disulfide, and the aluminum oxide was separated from the flaky molybdenum disulfide, causing the flaky molybdenum disulfide to be stacked layer by layer, reducing the thermal conductivity of the aluminum-silicon-based composite material.

[0082] Test Example 2: Density Detection

[0083] The density of the aluminum-silicon based composite materials obtained in Examples 1 to 4 and Comparative Examples 1 to 4 was tested. The test results are shown in Table 2.

[0084] Table 2. Density of aluminum-silicon based composite materials obtained in Examples 1 to 4 and Comparative Examples 1 to 4

[0085]

[0086]

[0087] It can be observed in Table 2 that the aluminum-silicon-based composite materials prepared in Examples 1 to 4 have good compactness compared with the aluminum-silicon-based composite materials prepared in Comparative Examples 1 to 4. This is attributed to the transient liquid phase sintering performance brought about by the introduction of low-melting-point bismuth powder. During the temperature-raising sintering process, the low-melting-point bismuth powder melts to form a liquid phase that diffuses into the aluminum-silicon alloy with a higher melting point that is still in the solid phase, and an infiltration effect occurs between the surfaces of the two components of the aluminum-silicon alloy. The liquid phase wets the surrounding high-melting-point metal or alloy. The capillary force generated during the period will lead to densification, which promotes the aluminum-silicon-based composite material to quickly complete sintering and densification; in addition, direct current electric field assisted sintering is introduced during the sintering process, and the microscopic structure of the aluminum-silicon-based composite material is arranged in a more compact manner through the combined action of sintering temperature-direct current electric field assistance-pressure, and the material has a higher degree of densification.

[0088] The above-described embodiments provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected.

Claims

1. A method for preparing an aluminum-silicon based composite material, characterized in that: The preparation method comprises the following steps: In an inert gas protection environment, aluminum silicon alloy, bismuth powder, grinding balls and anhydrous ethanol are mixed and ball-milled once, and then modified molybdenum disulfide is added for secondary ball-milling. After the secondary ball-milling, the mixed powder is washed and dried to obtain a mixed powder; the mixed powder is pre-pressed in a mold and then placed in a FHP rapid sintering device, a graphite electrode pressure head is placed on both sides of the mold, a direct current is passed, and pressure is heated and then kept warm for 15 to 30 minutes to obtain the aluminum silicon-based composite material.

2. The method for preparing an aluminum-silicon based composite material according to claim 1, characterized in that: The preparation of the modified molybdenum disulfide comprises the following steps: Ammonium molybdate tetrahydrate and thiourea are dispersed in deionized water, subjected to ultrasonic treatment for 10 to 20 minutes, reacted in an environment of 200 to 220° C. for 8 to 10 hours, and centrifuged and washed to obtain flaky molybdenum disulfide; flaky molybdenum disulfide is dispersed in a mixed solvent, aluminum chloride hexahydrate and ammonium bicarbonate are added, the pH value is adjusted to 8 to 9, stirred for 30 to 60 minutes, and then a surfactant is added, stirred for reaction for 2 to 3 hours, and then allowed to stand for 12 to 24 hours, washed and dried, and then calcined in an environment of 700 to 800° C. for 3 to 6 hours to obtain the modified molybdenum disulfide.

3. The method for preparing an aluminum-silicon based composite material according to claim 2, characterized in that: The weight ratio of the ammonium molybdate tetrahydrate to thiourea is 1:1-2.

4. The method for preparing an aluminum-silicon based composite material according to claim 2, characterized in that: The weight ratio of the flaky molybdenum disulfide, aluminum chloride hexahydrate and ammonium bicarbonate is 1:1.0-1.5:2.0-2.

5.

5. The method for preparing an aluminum-silicon based composite material according to claim 2, characterized in that: The weight ratio of the aluminum chloride hexahydrate to the surfactant is 1:10-20.

6. The method for preparing an aluminum-silicon based composite material according to claim 1, characterized in that: The aluminum-silicon alloy includes Al-Si27, Al-Si40, Al-Si50 or Al-Si70.

7. The method for preparing an aluminum-silicon based composite material according to claim 1, characterized in that: The dosage of the bismuth powder is 1-2% of the weight of the aluminum silicon alloy.

8. The method for preparing an aluminum-silicon based composite material according to claim 1, characterized in that: The grinding speed of the first ball milling is 250-300 rpm and the grinding time is 5-8 hours.

9. The method for preparing an aluminum-silicon based composite material according to claim 1, characterized in that: The grinding speed of the secondary ball milling is 150-200 rpm and the grinding time is 2-3 hours.

10. An aluminum-silicon based composite material prepared by the method for preparing an aluminum-silicon based composite material according to any one of claims 1 to 9.

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