Metal heat conduction material as well as preparation method and application thereof

Abstract

The invention discloses a metal heat conduction material and a preparation method and application thereof, and relates to the technical field of gallium-tin-indium alloy preparation. The preparation method of the metal heat conduction material comprises the following steps that gallium-tin-indium alloy in a molten state, SiC, monatomic silicon, metal aluminum and metal magnesium are mixed and smelted, molten composite metal is obtained, when the molten composite metal is solidified, pressure is increased by 15-30 MPa, and the metal heat conduction material is prepared. According to the preparation method, through cooperation of all the components and certain pressurization during solidification, the obtained metal heat conduction material is endowed with excellent heat conduction performance, hardness and dimensional stability, and the technical problems that the metal heat conduction material is low in heat conductivity, large in thermal expansion coefficient and prone to deformation at high temperature, and consequently the heat dissipation efficiency is reduced are solved; the technical effects of prolonging the service life of the metal heat conduction material and increasing the use temperature are achieved.

Description

Technical Field

[0001] The present application relates to the technical field of gallium-tin-indium alloy preparation, and in particular to a metal thermal conductive material and a preparation method and application thereof. Background Art

[0002] Heat sinks are components that physically or chemically remove heat from heat sources, maintaining equipment operating within a safe temperature range. They are key components for ensuring the stable operation of electronic devices, engines, and other equipment, and play an indispensable role in electronics cooling and thermal management. Ideal heat sink materials require excellent thermal conductivity, good dimensional stability, and a wide operating temperature range.

[0003] Aluminum- and copper-based alloys are often used as metal materials in heat sink components due to their excellent thermal conductivity. However, they suffer from large thermal expansion coefficients, making them prone to deformation at high temperatures, which can affect the fit between the heat sink and the heat source and even damage the heat sink's own structure, thereby reducing heat dissipation efficiency. Furthermore, their thermal conductivity decreases at high temperatures, leading to lower operating temperatures. Gallium metal also exhibits outstanding thermal conductivity, but its low melting point makes it unsuitable for high-temperature applications. Its alloys, such as gallium-tin-indium alloy, have high melting points but low thermal conductivity and a large thermal expansion coefficient, making them unsuitable as ideal metal thermal conductive materials for heat sink components. Summary of the Invention

[0004] The present application provides a metal thermal conductive material and its preparation method and application, in order to at least solve the problems in the related art that the metal thermal conductive material used in the heat dissipation component has low thermal conductivity, large thermal expansion coefficient, easy deformation at high temperature, thereby reducing the heat dissipation efficiency, and low operating temperature.

[0005] The present application provides a method for preparing a metal thermal conductive material, comprising the following steps: Step S1: mixing the molten gallium-tin-indium alloy with SiC, elemental silicon, metallic aluminum, and metallic magnesium, and subjecting the mixture to a heating treatment to obtain a molten composite metal; Step S2: solidify the molten composite metal to obtain a metal thermal conductive material, and apply a pressure of 15 to 30 MPa during solidification.

[0006] The present application provides a metal thermal conductive material prepared by the above preparation method.

[0007] The present application also provides a heat dissipation device, comprising the above-mentioned metal thermal conductive material.

[0008] Through this application, the raw materials of the metal heat-conducting material include gallium-tin-indium alloy, SiC, elemental silicon, metallic aluminum, and metallic magnesium, and a pressure of 15-30 MPa is applied during the solidification stage of the preparation. Due to the combination of the use of each component and the pressure during solidification, the metal heat-conducting material is endowed with excellent thermal conductivity, hardness, and dimensional stability. Therefore, the technical problems of low thermal conductivity, large thermal expansion coefficient, and easy deformation at high temperatures, which reduce the heat dissipation efficiency of the metal heat-conducting material, can be solved, and the technical effect of extending the service life of the metal heat-conducting material and increasing its use temperature is achieved, enabling the metal heat-conducting material to be better applied to high-temperature scenarios such as optoelectronic devices and avionics. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] To more clearly illustrate the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0010] Figure 1 SEM image of the metal heat-conducting material obtained in Embodiment 1 of the present application; Figure 2 Bar chart of the thermal conductivity of the metal heat-conducting materials prepared in Embodiments 1-3 and Comparative Example 1 of the present application; Figure 3 Line chart of the hardness of the metal heat-conducting materials prepared in Embodiments 1-3 and Comparative Example 1 of the present application; Figure 4 Bar chart of the thermal conductivity of the metal heat-conducting materials prepared in Embodiment 1, Embodiments 4-5, and Comparative Example 2 of the present application; Figure 5 Curve chart of the thermal expansion coefficient of the metal heat-conducting materials prepared in Embodiments 1-3 and Comparative Example 3 of the present application varying with temperature; Figure 6 Curve chart of the thermal expansion coefficient of the metal heat-conducting materials prepared in Embodiment 1, Embodiments 6-8 of the present application varying with temperature; Figure 7 Line chart of the hardness change of the metal heat-conducting materials prepared in Embodiment 1, Embodiments 9-11, and Comparative Example 4 of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0011] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the protection scope of the present application.

[0012] For those not specifying the specific experimental procedures or conditions in the examples, the operations or conditions of the conventional experimental procedures described in the literature in this field can be followed. For the reagents or instruments without indicating the manufacturer, they are all conventional reagent products or instruments that can be obtained through commercial purchase.

[0013] In order to enable those skilled in the art of this technical field to better understand the solution of this application, the following further detailed description of this application will be given in conjunction with the accompanying drawings and specific embodiments.

[0014] The embodiment of this application provides a preparation method of a metal thermal conductive material, including the following steps: Step S1: Mix the molten gallium-tin-indium alloy with SiC, elemental silicon, metallic aluminum, and metallic magnesium, and obtain a molten composite metal through heat treatment. Step S2: Solidify the molten composite metal to obtain a metal thermal conductive material, and apply a pressure of 15 - 30 MPa during solidification.

[0015] Melting is a first-order phase transition, in which there are increases in enthalpy, entropy, and volume; the temperature at which melting occurs is the melting temperature, and the liquid phase formed by the solid substance after reaching the melting temperature is called the molten state.

[0016] In the preparation method of the metal thermal conductive material provided by this application, typically and non-limitingly, solidification can be carried out at room temperature, such as 25°C.

[0017] The metal thermal conductive material prepared by this preparation method has a lower coefficient of thermal expansion, higher thermal conductivity and hardness, can be used as a thermal conductive material at a higher temperature without being easily deformed, thereby affecting heat dissipation and subsequent use, and has strong reliability and durability.

[0018] Among them, the use of the gallium-tin-indium alloy endows this metal thermal conductive material with a certain basic thermal conductivity; the addition of SiC further improves the thermal conductivity and hardness of the metal thermal conductive material; the addition of elemental silicon, metallic aluminum, and metallic magnesium helps to reduce the coefficient of thermal expansion of this metal thermal conductive material; a certain pressure during solidification enables this metal thermal conductive material to have higher hardness. In this application, through the synergistic cooperation of the composition and preparation process of the metal thermal conductive material, the phase composition, microstructure, interface bonding, and internal stress state of the material are regulated, and the optimization of thermal conductivity, hardness, and coefficient of thermal expansion is achieved.

[0019] Specifically, the gallium-tin-indium alloy has a high free electron density. Under an externally applied temperature gradient, free electrons transfer heat through directional movement, forming a relatively high basic thermal conductivity. SiC is a high-thermal-conductivity ceramic phase. In its crystal structure, the covalent bonds between atoms are strong and the atomic vibration frequency is high, and it can transfer heat through the phonon heat conduction mechanism. The dispersion of SiC in the gallium-tin-indium alloy can form a "thermal conduction network", making up for the possible defects in the heat conduction path in the gallium-tin-indium alloy, reducing the interfacial thermal resistance, and thus synergistically improving the overall thermal conductivity. At the same time, SiC itself has extremely high hardness and a strong interfacial bonding force with the gallium-tin-indium alloy. When SiC is embedded in the gallium-tin-indium alloy as a reinforcing phase, it can effectively hinder the movement of dislocations, improve the hardness of the material through the dispersion strengthening mechanism, and can also bear external loads, reducing the deformation of the matrix, and further enhancing the rigidity of the material. The crystal structure of elemental silicon is stable, the bond energy between atoms is high, the amplitude of atomic vibration is small when the temperature rises, and the volume change rate is low; the elemental silicon added to the gallium-tin-indium alloy can dilute the high expansion characteristics of the metal matrix through the physical mixing effect, thereby reducing the overall thermal expansion coefficient. Metals aluminum and magnesium have relatively low densities, and can further adjust the phase composition and microstructure of the final metal thermal conductive material; metal aluminum can form a solid solution with the gallium-tin-indium alloy, and to a certain extent reduce the amplitude of lattice thermal vibration through solid solution strengthening; metal magnesium can form a low-expansion compound with other components in the alloy, such as Mg2Si, and further optimize the overall thermal stability through the low-expansion characteristics of the second phase. Applying a certain pressure during the solidification process can promote the filling of the microscopic pores by the liquid metal, reduce defects such as pores and shrinkage porosity, improve the density of the material, and enhance the ability of the material to resist plastic deformation; it can also increase the nucleation rate, inhibit grain growth, form a fine grain strengthening effect, and the finer grains form more grain boundaries, increasing the resistance to dislocation movement and increasing the hardness of the material; moreover, part of the compressive stress can remain after solidification under the external pressure, offsetting the tensile stress caused by the external load, equivalently enhancing the yield strength and hardness of the material.

[0020] In some optional embodiments, in step S1, SiC is added to the molten gallium-tin-indium alloy, and heat treatment is carried out at the first heating temperature to obtain an intermediate molten metal; the first heating temperature is 295-305 °C; Then, elemental silicon, metal aluminum and metal magnesium are added to the intermediate molten metal, and heat treatment is carried out at the second heating temperature and the third heating temperature in sequence to obtain a molten composite metal; or, any two of elemental silicon, metal aluminum and metal magnesium are added to the intermediate molten metal, after heat treatment at the second heating temperature, it is cooled to the third heating temperature, and the remaining part of elemental silicon, metal aluminum and metal magnesium is added, and heat treatment is carried out at the third heating temperature to obtain a molten composite metal; wherein, the second heating temperature is 745-755 °C, and the third heating temperature is 695-705 °C.

[0021] In some optional embodiments, by mass parts, the molten composite metal includes: 100 parts in total of gallium-tin-indium alloy and SiC, 0.8 - 5.2 parts of elemental silicon, 0.8 - 1.2 parts of metallic aluminum, and 0.8 - 1.2 parts of metallic magnesium.

[0022] In some optional embodiments, the heating treatment time at the first heating temperature, at the second heating temperature, or at the third heating temperature is 8 - 24 min.

[0023] In some optional embodiments, during the heating treatment process, an operation of stirring is further included; the stirring time is 8 - 12 min. Typically and non-limitingly, stirring is performed in the first half of the heating treatment to make the components mix more uniformly; the stirring includes mechanical stirring; further, the stirring speed is 450 - 550 rmp / min.

[0024] In some optional embodiments, in step S1, the method for preparing the molten composite metal includes: By mass parts, add 0.8 - 1.2 parts of metallic aluminum and 4.8 - 5.2 parts of elemental silicon to 100 parts of intermediate molten metal, heat up to the second heating temperature for heating treatment. During the heating treatment process, stir for 8 - 12 min first, then stop stirring and keep warm for 8 - 12 min, cool down to the third heating temperature, add 0.8 - 1.2 parts of metallic magnesium, and conduct heating treatment at the third heating temperature. During the heating treatment process, stir for 8 - 12 min first, then stop stirring and keep warm for 8 - 12 min to obtain the molten composite metal; Or, by mass parts, add 0.8 - 1.2 parts of metallic aluminum, 4.8 - 5.2 parts of elemental silicon, and 0.8 - 1.2 parts of metallic magnesium to 100 parts of intermediate molten metal, heat up to the second heating temperature for heating treatment. During the heating treatment process, stir for 8 - 12 min first, then stop stirring and keep warm for 8 - 12 min, cool down to the third heating temperature, and conduct heating treatment for 8 - 12 min to obtain the molten composite metal; Or, by mass parts, add 0.8 - 1.2 parts of metallic aluminum and 0.8 - 1.2 parts of metallic magnesium to 100 parts of intermediate molten metal, heat up to the second heating temperature for heating treatment. During the heating treatment process, stir for 8 - 12 min first, then stop stirring and keep warm for 8 - 12 min, cool down to the third heating temperature, add 4.8 - 5.2 parts of elemental silicon, and conduct heating treatment at the third heating temperature. During the heating treatment process, stir for 8 - 12 min first, then stop stirring and keep warm for 8 - 12 min to obtain the molten composite metal; Alternatively, in parts by mass, 0.8 - 1.2 parts of metallic aluminum and 0.8 - 1.2 parts of elemental silicon are added to 100 parts of intermediate molten metal, and the temperature is raised to the second heating temperature for heat treatment. During the heat treatment process, first stir for 8 - 12 min, then stop stirring and keep warm for 8 - 12 min. After cooling to the third heating temperature, 0.8 - 1.2 parts of metallic magnesium are added, and heat treatment is carried out at the third heating temperature. During the heat treatment process, first stir for 8 - 12 min, then stop stirring and keep warm for 8 - 12 min to obtain molten composite metal.

[0025] In some more preferred embodiments, in step S1, the method for preparing the molten composite metal is as follows: in parts by mass, 0.8 - 1.2 parts of metallic aluminum and 4.8 - 5.2 parts of elemental silicon are added to 100 parts of intermediate molten metal, and the temperature is raised to the second heating temperature for heat treatment. During the heat treatment process, first stir for 8 - 12 min, then stop stirring and keep warm for 8 - 12 min. After cooling to the third heating temperature, 0.8 - 1.2 parts of metallic magnesium are added, and heat treatment is carried out at the third heating temperature. During the heat treatment process, first stir for 8 - 12 min and keep warm for 8 - 12 min to obtain molten composite metal. Using the feeding method of first adding metallic aluminum and elemental silicon to the intermediate molten metal, after heat treatment for a certain time, cooling and then adding metallic magnesium, and continuing heat treatment, and the feeding amounts of 0.8 - 1.2 parts of metallic aluminum, 4.8 - 5.2 parts of elemental silicon, and 0.8 - 1.2 parts of metallic magnesium corresponding to 100 parts of intermediate molten metal can further reduce the thermal expansion coefficient of the finally obtained metal thermal conductive material.

[0026] In some alternative embodiments, in the gallium - tin - indium alloy, by mass percentage, it contains 60% - 70% of gallium, 20% - 30% of tin, and 5% - 10% of indium. For example, in the gallium - tin - indium alloy, by mass percentage, it contains 65% of gallium, 30% of tin, and 5% of indium; or, it contains 60% of gallium, 30% of tin, and 10% of indium; or, it contains 70% of gallium, 20% of tin, and 10% of indium.

[0027] In some alternative embodiments, in the molten composite metal, the mass ratio of the gallium - tin - indium alloy to SiC is 7:3 - 9:1. For example, the mass ratio of the gallium - tin - indium alloy to SiC can be 7:3, 8:2, or 9:1.

[0028] In some more preferred embodiments, in the molten composite metal, the mass ratio of the gallium - tin - indium alloy to SiC is 7:3; because SiC itself has extremely high hardness, under the condition of controlling a relatively high mass proportion of SiC, the obtained metal thermal conductive material can also have higher hardness, and at the same time, controlling the mass ratio of the two at 7:2 will not have a negative impact on other properties of the metal thermal conductive material.

[0029] In some optional embodiments, the preparation method of the gallium-tin-indium alloy includes: taking metallic gallium, metallic tin, and metallic indium by mass percentage, heating them to 295 - 305 °C in an inert atmosphere until the metallic gallium, metallic tin, and metallic indium melt into a completely molten state, and holding for 8 - 12 min to fully mix and homogenize the metallic gallium, metallic tin, and metallic indium in the molten state, thereby obtaining the gallium-tin-indium alloy.

[0030] The inert atmosphere includes at least one of a nitrogen atmosphere and a noble gas atmosphere; for example, the inert atmosphere can be a nitrogen atmosphere, an argon atmosphere, or a nitrogen-argon mixed atmosphere.

[0031] In some optional embodiments, the preparation method includes the following steps: S1: In the gallium-tin-indium alloy, by mass percentage, it contains 70% gallium, 20% tin, and 10% indium. Take metallic gallium, metallic tin, and metallic indium, and heat the metallic gallium, metallic tin, and metallic indium to 300 °C in an inert atmosphere, hold for 10 min, to obtain the gallium-tin-indium alloy; at this gallium-tin-indium ratio, the obtained metal thermal conductive material has a higher thermal conductivity; S2: At the first heating temperature, by mass parts, add 30 parts of SiC to 70 parts of the gallium-tin-indium alloy, stir for 20 min, and hold, to obtain an intermediate molten metal; at this mass ratio of the gallium-tin-indium alloy to SiC, the obtained metal thermal conductive material has a higher strength; S3: By mass parts, add 1 part of metallic aluminum and 5 parts of elemental silicon to 100 parts of the intermediate molten metal, raise the temperature to the second heating temperature for heat treatment. During the heat treatment process, first stir for 10 min, then stop stirring and hold for 10 min, cool down to the third heating temperature, add 1 part of metallic magnesium, and conduct heat treatment at the third heating temperature. During the heat treatment process, first stir for 10 min, then stop stirring and hold for 10 min, to obtain a molten composite metal; S4: At room temperature, solidify the molten composite metal to obtain a metal thermal conductive material, and apply a pressure of 15 - 30 MPa during solidification.

[0032] In order to further improve the purity of the obtained metal thermal conductive material, before the solidification operation, it further includes the steps of adding hexachloroethane to the molten composite metal at the third temperature, stirring, standing, and skimming the slag. The mass ratio of hexachloroethane to the molten composite metal is 1:205 - 215, the stirring time is 5 min, and the standing time is 15 min. Hexachloroethane can decompose into gases at high temperatures, and these gases form bubbles in the molten composite metal, adsorb and carry non-metallic impurities to float to the surface of the molten composite metal, and then are removed by skimming the slag, which can further improve the compactness and mechanical properties of the alloy.

[0033] To better dope SiC in the metal thermal conductive material, before preparation, it also includes the step of cleaning SiC, specifically including: taking SiC particles, first cleaning them in hydrofluoric acid to remove surface oxides, then second cleaning them in a silane coupling agent and ethanol solution with a mass ratio of 1:98 - 102, and then drying. Among them, the concentration of hydrofluoric acid is 5wt%, the time for the first cleaning and the second cleaning is 30 min, the cleaning method includes ultrasonic cleaning, the drying temperature is 60 °C, and the time is 2 h until the SiC particles are completely dry.

[0034] According to one aspect of the embodiments of the present application, there is also provided a metal thermal conductive material prepared by the preparation method of any of the above metal thermal conductive materials.

[0035] According to one aspect of the embodiments of the present application, there is also provided a heat dissipation device including the above metal thermal conductive material. It can conduct heat more efficiently, improve the cooling efficiency of the heat dissipation device, avoid problems such as performance degradation, operation failure, and hardware damage of the device to be cooled caused by overheating, ensure the stable operation of the device to be cooled, and extend its service life. At the same time, the heat dissipation device still has good thermal conductivity at high temperatures, can be applied to a wide range of working conditions, and can further help broaden the application scenarios of the device to be cooled.

[0036] Example 1 This example provides a metal thermal conductive material and its preparation method, including the following steps: (1) Take SiC particles, place them in 5% hydrofluoric acid and ultrasonically clean for 30 min to remove surface oxides; then place them in a silane coupling agent KH570 and ethanol solution with a mass ratio of 1:100 and ultrasonically clean for 30 min; then place them in a drying oven at 60 °C and dry for 2 h to obtain pretreated SiC particles.

[0037] (2) In the gallium-tin-indium alloy, by mass percentage, it contains 70% gallium, 20% tin, and 10% indium. Weigh metal gallium, metal tin, and metal indium, and under a nitrogen atmosphere, mix and heat metal gallium, metal tin, and metal indium to 300 °C to make them completely molten, and keep the molten state for 10 min to obtain a gallium-tin-indium alloy.

[0038] (3) By mass, add 30 parts of the pretreated SiC particles in step (1) to 70 parts of the molten gallium-tin-indium alloy at 300 °C, and conduct a heat treatment at 300 °C. First, use a stirrer to stir at a speed of 500 rmp / min for 20 min to make them mix evenly, then stop stirring, and continue to keep the temperature at 300 °C for heat treatment to obtain an intermediate molten metal.

[0039] (4) At 300 °C, by mass, 1 part of aluminum metal, 5 parts of elemental silicon are added to 100 parts of the intermediate molten metal, and the temperature is raised to 750 °C for heat treatment. During the heat treatment, it is first stirred at a speed of 500 rmp / min for 10 min to make it evenly mixed, then the stirring is stopped, and the heat treatment is continued for 10 min. The temperature is lowered to 700 °C, 1 part of magnesium metal is added, and heat treatment is carried out. During the heat treatment, it is first stirred at a speed of 500 rmp / min for 10 min to make it evenly mixed, then the stirring is stopped, and the heat treatment is continued for 10 min to obtain a molten composite metal.

[0040] (5) By mass, 0.5 part of C2Cl6 is added to 107 parts of the molten composite metal, stirred for 5 min, allowed to stand for 15 min, and then the slag is skimmed off.

[0041] (6) The molten composite metal after skimming the slag is put into a mold for cooling and solidification. The solidification temperature is 25 °C, and the pressure during solidification is 30 MPa to obtain a metal heat-conducting material.

[0042] Example 2 This example provides a metal heat-conducting material and its preparation method. Compared with Example 1, the difference is only that step (3) is: by mass, 20 parts of the SiC particles pretreated in step (1) are added to 80 parts of the molten gallium-tin-indium alloy at 300 °C, and heat treatment is carried out at 300 °C. During the heat treatment, it is first stirred with a stirrer at a speed of 500 rmp / min for 20 min to make it evenly mixed, then the stirring is stopped, and the heat treatment is continued while maintaining the temperature at 300 °C to obtain an intermediate molten metal.

[0043] Example 3 This example provides a metal heat-conducting material and its preparation method. Compared with Example 1, the difference is only that step (3) is: by mass, 10 parts of the SiC particles pretreated in step (1) are added to 90 parts of the molten gallium-tin-indium alloy at 300 °C, and heat treatment is carried out at 300 °C. During the heat treatment, it is first stirred with a stirrer at a speed of 500 rmp / min for 20 min to make it evenly mixed, then the stirring is stopped, and the heat treatment is continued while maintaining the temperature at 300 °C to obtain an intermediate molten metal.

[0044] Example 4 This example provides a metal heat-conducting material and its preparation method. Compared with Example 1, the difference is only that step (2) is: in the gallium-tin-indium alloy, by mass percentage, it contains 65% gallium, 30% tin, and 5% indium. Weigh metal gallium, metal tin, and metal indium, and under a nitrogen atmosphere, mix and heat metal gallium, metal tin, and metal indium to 300 °C to make them completely molten and keep the molten state for 10 min to obtain a gallium-tin-indium alloy.

[0045] Example 5 This example provides a metal thermal conductive material and its preparation method. Compared with Example 1, the difference is only that step (2) is as follows: In the gallium-tin-indium alloy, by mass percentage, it contains 60% gallium, 30% tin, and 10% indium. Weigh metal gallium, metal tin, and metal indium, and under a nitrogen atmosphere, mix and heat metal gallium, metal tin, and metal indium to 300 °C until they are completely melted, and keep the molten state for 10 min to obtain the gallium-tin-indium alloy.

[0046] Example 6 This example provides a metal thermal conductive material and its preparation method. Compared with Example 1, the difference is only that step (4) is as follows: At 300 °C, by mass parts, add 1 part of metal aluminum, 5 parts of elemental silicon, and 1 part of metal magnesium to 100 parts of intermediate molten metal, heat up to 750 °C for heat treatment. During the heat treatment, first stir at a speed of 500 rmp / min for 10 min to make them mix evenly, then stop stirring, continue the heat treatment for 10 min, cool down to 700 °C, and continue the heat treatment for 10 min to obtain the molten composite metal.

[0047] Example 7 This example provides a metal thermal conductive material and its preparation method. Compared with Example 1, the difference is only that step (4) is as follows: At 300 °C, by mass parts, add 1 part of metal aluminum and 1 part of metal magnesium to 100 parts of intermediate molten metal, heat up to 750 °C for heat treatment. During the heat treatment, first stir at a speed of 500 rmp / min for 10 min to make them mix evenly, then stop stirring, continue the heat treatment for 10 min, cool down to 700 °C, add 5 parts of elemental silicon, and conduct heat treatment. During the heat treatment, first stir at a speed of 500 rmp / min for 10 min to make them mix evenly, then stop stirring, continue the heat treatment for 10 min to obtain the molten composite metal.

[0048] Example 8 This example provides a metal thermal conductive material and its preparation method. Compared with Example 1, the difference is only that step (4) is as follows: At 300 °C, by mass parts, add 1 part of metal aluminum and 1 part of elemental silicon to 100 parts of intermediate molten metal, heat up to 750 °C for heat treatment. During the heat treatment, first stir at a speed of 500 rmp / min for 10 min to make them mix evenly, then stop stirring, continue the heat treatment for 10 min, cool down to 700 °C, add 1 part of metal magnesium, and conduct heat treatment. During the heat treatment, first stir at a speed of 500 rmp / min for 10 min to make them mix evenly, then stop stirring, continue the heat treatment for 10 min to obtain the molten composite metal.

[0049] Example 9 This embodiment provides a metal thermal conductive material and a preparation method thereof. Compared with Embodiment 1, the only difference is that in step (6), the molten composite metal after slag skimming is put into a mold for cooling and solidification. The solidification temperature is 25 °C, and the pressure applied during solidification is 15 MPa, obtaining the metal thermal conductive material.

[0050] Embodiment 10 This embodiment provides a metal thermal conductive material and a preparation method thereof. Compared with Embodiment 1, the only difference is that in step (6), the molten composite metal after slag skimming is put into a mold for cooling and solidification. The solidification temperature is 25 °C, and the pressure applied during solidification is 20 MPa, obtaining the metal thermal conductive material.

[0051] Embodiment 11 This embodiment provides a metal thermal conductive material and a preparation method thereof. Compared with Embodiment 1, the only difference is that in step (6), the molten composite metal after slag skimming is put into a mold for cooling and solidification. The solidification temperature is 25 °C, and the pressure applied during solidification is 25 MPa, obtaining the metal thermal conductive material.

[0052] Comparative Example 1 This comparative example provides a metal thermal conductive material and a preparation method thereof. Compared with Embodiment 1, the only difference is that step (1) is not carried out, and step (3) is as follows: taking 100 parts of molten gallium-tin-indium alloy at 300 °C by mass, performing a heat treatment at 300 °C. In the heat treatment, first use a stirrer to stir at a speed of 500 rmp / min for 20 min to make it further mixed evenly, then stop stirring, and continue to keep the temperature at 300 °C for heat treatment, obtaining an intermediate molten metal.

[0053] Comparative Example 2 This comparative example provides a metal thermal conductive material and a preparation method thereof. Compared with Embodiment 1, the only difference is that step (2) is to prepare a gallium-indium alloy, specifically: according to the gallium-indium alloy, weighing metallic gallium and metallic indium containing 70% gallium and 30% indium by mass percentage. Under a nitrogen atmosphere, mix and heat metallic gallium and metallic indium to 300 °C to make them completely molten, and keep the molten state for 10 min, obtaining the gallium-indium alloy.

[0054] Comparative Example 3 This comparative example provides a metal thermal conductive material and a preparation method thereof. Compared with Embodiment 1, the only difference is that step (4) is not carried out, and directly take the intermediate molten metal obtained in step (3) for step (5) and subsequent operations.

[0055] Comparative Example 4 This comparative example provides a metal heat-conducting material and a preparation method thereof. Compared with Example 1, the only difference is that in step (6), the molten composite metal after slag skimming is put into a mold for cooling and solidification. The solidification temperature is 25 °C, and the pressure during solidification is 5 MPa, obtaining the metal heat-conducting material.

[0056] Test Example 1 Take the metal heat-conducting material obtained in Example 1 and observe it under SEM. The image obtained at a magnification of 10,000 times is shown in Figure 1 . From Figure 1 it can be seen that there are a small number of sparse micropores on the metal surface. These are the fine micropores formed by SiC dispersed in the metal heat-conducting material after melting and can only be observed at a magnification of 10,000 times. Therefore, it can be considered that the metal heat-conducting material provided by this application has a smooth and flat surface. When applied to electronic components, it can avoid the accumulation of charges at sharp parts, thus avoiding the tip discharge phenomenon; and the smooth and flat metal surface can further improve the fitting accuracy during preparation, etc., comprehensively extending the service life of the manufactured electronic components.

[0057] Test Example 2 Take the metal heat-conducting materials prepared in Examples 1 to 3 and Comparative Example 1, and test their thermal conductivity and hardness respectively. The thermal conductivity is tested by a flat-plate thermal conductivity meter, and the test condition is room temperature; the hardness is tested by a Rockwell hardness tester. Process the data, and the histogram of the thermal conductivity of the metal heat-conducting materials prepared in Examples 1 to 3 and Comparative Example 1 is shown in Figure 2 , and the line graph of the hardness is shown in Figure 3 .

[0058] From Figure 2 it can be seen that the thermal conductivity of the metal heat-conducting material obtained in Comparative Example 1 without adding SiC is the lowest, about 70 W / m·K. The thermal conductivity of the metal heat-conducting materials added with SiC in Examples 1 to 3 is significantly higher than that of Comparative Example 1. In Example 1, the mass ratio of the molten gallium-tin-indium alloy to SiC particles is 7:3, and the thermal conductivity is close to 200 W / m·K; in Example 2, the mass ratio of the molten gallium-tin-indium alloy to SiC particles is 8:2, and the thermal conductivity is about 170 W / m·K; in Example 3, the mass ratio of the molten gallium-tin-indium alloy to SiC particles is 9:1, and the thermal conductivity is about 140 W / m·K. Figure 2 In the histogram of

[0059] From Figure 3 it can be seen that under different SiC addition amounts, the change trend of the metal heat-conducting material is the same as that of Figure 2The trends of thermal conductivity change are basically the same. In Comparative Example 1 without SiC addition, the hardness of the obtained metal thermal conductive material is the lowest, about 40 HRB; the hardness of the metal thermal conductive materials with SiC addition in Examples 1 to 3 is significantly improved compared with Comparative Example 1. Even in Example 3 with a mass ratio of molten gallium-tin-indium alloy to SiC particles of 9:1, its hardness is also about 65 HRB, much higher than that of Comparative Example 1. Compared with Example 3, in Examples 2 and 1 with mass ratios of molten gallium-tin-indium alloy to SiC particles of 8:2 and 7:3 respectively, as the SiC addition amount gradually increases, the hardness of the metal thermal conductive material also gradually increases. The hardness of Example 2 is about 75 HRB, and the hardness of Example 1 is about 87 HRB. The metal thermal conductive material obtained in Example 1 with a mass ratio of molten gallium-tin-indium alloy to SiC particles of 7:3 has the highest hardness.

[0060] Test Example 3 Take the metal thermal conductive materials prepared in Example 1, Examples 4 and 5, and Comparative Example 2, and test their thermal conductivities respectively. The thermal conductivity test method is the same as that in Test Example 2. Process the data, and the column chart of the thermal conductivities of the metal thermal conductive materials prepared in Example 1, Examples 4 and 5, and Comparative Example 2 is shown in Figure 4 .

[0061] From Figure 4 it can be seen that the thermal conductivity of Comparative Example 2 is the lowest, only about 100 W / m·K. This is because in Comparative Example 2, a gallium-indium alloy without tin is used as the substrate instead of a gallium-indium-tin alloy. In Examples 1, 4, and 5 with a gallium-tin-indium alloy as the substrate, the thermal conductivities of the obtained metal thermal conductive materials are significantly higher than that of Comparative Example 2. Among Examples 1, 4, and 5, the thermal conductivity of Example 4 with gallium, tin, and indium accounting for 65%, 30%, and 5% respectively in the gallium-tin-indium alloy is relatively low, about 170 W / m·K; the thermal conductivity of Example 5 with gallium, tin, and indium accounting for 60%, 30%, and 10% respectively in the gallium-tin-indium alloy is slightly higher than that of Example 4 but limited; while the thermal conductivity of Example 1 with gallium, tin, and indium accounting for 70%, 20%, and 10% respectively in the gallium-tin-indium alloy is significantly higher than those of Examples 4 and 5, reaching nearly 200 W / m·K, which is the optimal gallium-tin-indium alloy ratio in this application.

[0062] Test Example 4 Take the metal thermal conductive materials prepared in Examples 1 to 3 and Comparative Example 3, and test their thermal expansion coefficients respectively. The thermal expansion coefficients are tested by a thermomechanical analyzer. Process the data, and the curve chart of the thermal expansion coefficients of the metal thermal conductive materials prepared in Examples 1 to 3 and Comparative Example 3 changing with temperature is shown in Figure 5 .

[0063] From Figure 5It can be seen that for the metal thermal conductive material prepared in Comparative Example 3, since no aluminum metal, magnesium metal, and elemental silicon are added, the coefficient of thermal expansion is significantly higher. The coefficient of thermal expansion at 25 °C has reached as high as 16.5×10 -6 K -1 or more, and the coefficient of thermal expansion at 300 °C is as high as 21×10 -6 K -1 or more. Regardless of whether it is at high or low temperatures, this material has a greater risk of deformation and is not very suitable for use as a thermal conductive material. In Examples 1 to 3, although the mass ratios of the molten gallium-tin-indium alloy to the SiC particles used are different, since 1 part by mass of aluminum metal, 1 part by mass of magnesium metal, and 5 parts by mass of elemental silicon are added by the method of first adding aluminum metal and elemental silicon, heating up, stirring to make the mixture uniform and holding for a period of time, then cooling down, and adding magnesium metal and stirring to make the mixture uniform and holding for a period of time, the coefficients of thermal expansion of the prepared metal thermal conductive materials have all decreased to varying degrees compared with Comparative Example 3. Among them, in Example 1, the mass ratio of the molten gallium-tin-indium alloy to the SiC particles is 7:3, and the coefficient of thermal expansion of the obtained metal thermal conductive material reaches 15×10 -6 K -1 at a relatively high temperature, above 50 °C, and the coefficient of thermal expansion at 300 °C is still relatively low, around 18×10 -6 K -1 . In Example 2, the mass ratio of the molten gallium-tin-indium alloy to the SiC particles is 8:2. Although the coefficient of thermal expansion at 300 °C is lower than that of the metal thermal conductive material obtained in Example 1, the temperature at which the coefficient of thermal expansion reaches 15×10 -6 K -1 is also lower, below 50 °C. In Example 3, the mass ratio of the molten gallium-tin-indium alloy to the SiC particles is 9:1. Although the coefficient of thermal expansion reaches 15×10 -6 K -1 at a relatively high temperature, which is basically close to that of the metal thermal conductive material obtained in Example 1, but the coefficient of thermal expansion at 300 °C reaches 20×10 -6 K -1 or so. At this mass ratio of the gallium-tin-indium alloy to SiC, the obtained metal thermal conductive material is more suitable for use at lower temperatures.

[0064] Test Example 5 Take the metal thermal conductive materials prepared in Example 1 and Examples 6 to 8, and use the same method as in Test Example 4 to test their coefficients of thermal expansion respectively. Process the data, and the curve graphs showing the variation of the coefficients of thermal expansion of the metal thermal conductive materials prepared in Example 1 and Examples 6 to 8 with temperature are shown in Figure 6 .

[0065] From Figure 6As can be seen, in Example 1, 1 part by mass of Al and 5 parts by mass of Si were first added, the temperature was raised, and after stirring to make the mixture uniform, a heat treatment of continuing to keep warm for a period of time was carried out. Then the temperature was lowered, and 1 part by mass of Mg was added, and after stirring to make the mixture uniform, a heat treatment of continuing to keep warm for a period of time was carried out. In this way of adding metallic aluminum, metallic magnesium, and elemental silicon, the prepared metal heat-conducting material has a low coefficient of thermal expansion at high temperatures, and the temperature at which the coefficient of thermal expansion reaches 15×10 -6 K -1 is also relatively low. In Example 7, 1 part by mass of Al and 1 part by mass of Mg were first added, the temperature was raised, and after stirring to make the mixture uniform, a heat treatment of continuing to keep warm for a period of time was carried out. Then the temperature was lowered, and 5 parts by mass of Si were added, and after stirring to make the mixture uniform, a heat treatment of continuing to keep warm for a period of time was carried out. In this way of adding metallic aluminum, metallic magnesium, and elemental silicon, although the temperature at which the coefficient of thermal expansion reaches 15×10 -6 K -1 is also relatively low, but the coefficient of thermal expansion at 300 °C is relatively high, and it is more suitable for use at low temperatures. In Example 8, 1 part by mass of Al and 1 part by mass of Si were first added, the temperature was raised, and after stirring to make the mixture uniform, a heat treatment of continuing to keep warm for a period of time was carried out. Then the temperature was lowered, and 1 part by mass of Mg was added, and after stirring to make the mixture uniform, a heat treatment of continuing to keep warm for a period of time was carried out; in Example 6, 1 part by mass of Al, 5 parts by mass of Si, and 1 part by mass of Mg were added simultaneously, the temperature was raised, and after stirring to make the mixture uniform, a heat treatment of continuing to keep warm for a period of time was carried out. Then the temperature was lowered, and a heat treatment was continued for a period of time. The growth trend of the coefficient of thermal expansion of the metal heat-conducting materials prepared by these two feeding methods and the quality of the materials used is basically close to that in Example 1, but the initial coefficient of thermal expansion is relatively high. At 25 °C, in Example 8, it is about 15.7×10 -6 K -1 or so, and in Example 6, it is about 16.5×10 -6 K -1 or so, ultimately making the overall value relatively high. In Example 1, first adding 1 part by mass of Al and 5 parts by mass of Si, lowering the temperature after keeping warm for a period of time and then adding 1 part by mass of Mg is the best feeding method and mass ratio of the materials.

[0066] Test Example 6 Take the metal heat-conducting materials prepared in Example 1, Examples 9 to 11, and Comparative Example 4, and use the same method as in Test Example 2 to test their hardnesses respectively. The obtained data are shown in Table 1, and after processing the data, the broken line graph of the hardness changes of the metal heat-conducting materials prepared in Example 1, Examples 9 to 11, and Comparative Example 4 is shown in Figure 7 .

[0067] Table 1

[0068] Combined with Table 1 and Figure 7 it can be seen that in Comparative Example 4, the pressure applied during solidification is too low, only 5 MPa, resulting in a hardness of only 35 HRB for the finally obtained metal heat-conducting material, which is not easy to process and use. In Example 9, the pressure applied during solidification is increased to 15 MPa, and the hardness of the obtained metal heat-conducting material can reach the relatively high value of 75 HRB; in Examples 10, 11, and 1, the pressure applied during solidification is further increased, and the hardness of the obtained metal heat-conducting material increases slowly. In actual production, a reasonable pressure applied during solidification can be selected according to the cost and the required hardness of the target product.

[0069] The above has introduced in detail a metal heat-conducting material, its preparation method and application provided by the present application. Specific examples are used herein to elaborate on the principle and implementation manner of the present application. The description of the above examples is only used to help understand the method and its core idea of the present application. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present application, several improvements and modifications can still be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A preparation method of a metal heat-conducting material, characterized in that, It includes the following steps: Step S1: Mix the molten gallium-tin-indium alloy with SiC, elemental silicon, metallic aluminum, and metallic magnesium, and obtain a molten composite metal through heat treatment. Step S2: Solidify the molten composite metal to obtain a metal thermal conductive material, and apply a pressure of 15 to 30 MPa during solidification.

2. The preparation method of the metal heat-conducting material according to claim 1, characterized in that, In Step S1, add SiC to the molten gallium-tin-indium alloy, and perform heat treatment at the first heating temperature to obtain an intermediate molten metal; the first heating temperature is 295 to 305 °C. Then, add elemental silicon, metallic aluminum, and metallic magnesium to the intermediate molten metal, and perform heat treatment at the second heating temperature and the third heating temperature in sequence to obtain a molten composite metal; or, add any two of elemental silicon, metallic aluminum, and metallic magnesium to the intermediate molten metal, perform heat treatment at the second heating temperature, cool down to the third heating temperature, add the remaining part of elemental silicon, metallic aluminum, and metallic magnesium, and perform heat treatment at the third heating temperature to obtain a molten composite metal; wherein, the second heating temperature is 745 to 755 °C, and the third heating temperature is 695 to 705 °C.

3. The preparation method of the metal heat-conducting material according to claim 2, wherein, By mass, the molten composite metal includes: a total of 100 parts of gallium-tin-indium alloy and SiC, 0.8 to 5.2 parts of elemental silicon, 0.8 to 1.2 parts of metallic aluminum, and 0.8 to 1.2 parts of metallic magnesium. And / or, the time for heat treatment at the first heating temperature, at the second heating temperature, or at the third heating temperature is 8 to 24 min. And / or, during the heat treatment process, a stirring operation is further included; the stirring time is 8 to 12 min.

4. The preparation method of the metal heat-conducting material according to claim 3, characterized in that In Step S1, the method for preparing the molten composite metal includes: By mass, add 0.8 to 1.2 parts of metallic aluminum and 4.8 to 5.2 parts of elemental silicon to 100 parts of the intermediate molten metal, heat up to the second heating temperature for heat treatment, stir for 8 to 12 min first during the heat treatment process, then stop stirring and keep warm for 8 to 12 min, cool down to the third heating temperature, add 0.8 to 1.2 parts of metallic magnesium, and perform heat treatment at the third heating temperature. Stir for 8 to 12 min first during the heat treatment process, then stop stirring and keep warm for 8 to 12 min to obtain a molten composite metal. Or, by mass, add 0.8 to 1.2 parts of metallic aluminum, 4.8 to 5.2 parts of elemental silicon, and 0.8 to 1.2 parts of metallic magnesium to 100 parts of the intermediate molten metal, heat up to the second heating temperature for heat treatment, stir for 8 to 12 min first during the heat treatment process, then stop stirring and keep warm for 8 to 12 min, cool down to the third heating temperature, and perform heat treatment for 8 to 12 min to obtain a molten composite metal. Or, by mass parts, 0.8 - 1.2 parts of metallic aluminum and 0.8 - 1.2 parts of metallic magnesium are added to 100 parts of intermediate molten metal, heated to the second heating temperature for heat treatment. During the heat treatment process, first stir for 8 - 12 min, then stop stirring and keep warm for 8 - 12 min. Cool down to the third heating temperature, add 4.8 - 5.2 parts of elemental silicon, and conduct heat treatment at the third heating temperature. During the heat treatment process, first stir for 8 - 12 min, then stop stirring and keep warm for 8 - 12 min to obtain molten composite metal; Or, by mass parts, 0.8 - 1.2 parts of metallic aluminum and 0.8 - 1.2 parts of elemental silicon are added to 100 parts of intermediate molten metal, heated to the second heating temperature for heat treatment. During the heat treatment process, first stir for 8 - 12 min, then stop stirring and keep warm for 8 - 12 min. Cool down to the third heating temperature, add 0.8 - 1.2 parts of metallic magnesium, and conduct heat treatment at the third heating temperature. During the heat treatment process, first stir for 8 - 12 min, then stop stirring and keep warm for 8 - 12 min to obtain molten composite metal.

5. The preparation method of the metal heat-conducting material according to claim 4, characterized in that, In step S1, the method for preparing the molten composite metal is: by mass parts, 0.8 - 1.2 parts of metallic aluminum and 4.8 - 5.2 parts of elemental silicon are added to 100 parts of intermediate molten metal, heated to the second heating temperature for heat treatment. During the heat treatment process, first stir for 8 - 12 min, then stop stirring and keep warm for 8 - 12 min. Cool down to the third heating temperature, add 0.8 - 1.2 parts of metallic magnesium, and conduct heat treatment at the third heating temperature. During the heat treatment process, first stir for 8 - 12 min and keep warm for 8 - 12 min to obtain molten composite metal.

6. The preparation method of the metal heat-conducting material according to claim 1, characterized in that, In the gallium - tin - indium alloy, by mass percentage, it contains 60% - 70% of gallium, 20% - 30% of tin, and 5% - 10% of indium; And / or, in the molten composite metal, the mass ratio of the gallium - tin - indium alloy to SiC is 7:3 - 9:

1.

7. The preparation method of the metal heat-conducting material according to claim 6, characterized in that, The preparation method of the gallium - tin - indium alloy includes: taking metallic gallium, metallic tin, and metallic indium according to mass percentages, heating to 295 - 305 °C in an inert atmosphere, and keeping warm for 8 - 12 min to obtain the gallium - tin - indium alloy; And / or, in the molten composite metal, the mass ratio of the gallium - tin - indium alloy to SiC is 7:

3.

8. The preparation method of the metal heat-conducting material according to claim 7, wherein The preparation method includes the following steps: S1: In the gallium - tin - indium alloy, by mass percentage, it contains 70% of gallium, 20% of tin, and 10% of indium. Take metallic gallium, metallic tin, and metallic indium, and in an inert atmosphere, heat metallic gallium, metallic tin, and metallic indium to 300 °C and keep warm for 10 min to obtain the gallium - tin - indium alloy; S2: At the first heating temperature, by mass parts, add 30 parts of SiC to 70 parts of the gallium - tin - indium alloy, stir for 20 min, and keep warm to obtain the intermediate molten metal; S3: By mass fraction, add 1 part of metallic aluminum and 5 parts of elemental silicon into 100 parts of intermediate molten metal, heat it up to the second heating temperature for heat treatment. During the heat treatment process, stir for 10 min first, then stop stirring and keep warm for 10 min, cool down to the third heating temperature, add 1 part of metallic magnesium, and conduct heat treatment at the third heating temperature. During the heat treatment process, stir for 10 min first, then stop stirring and keep warm for 10 min to obtain molten composite metal; S4: At room temperature, solidify the molten composite metal to obtain a metal heat-conducting material, and apply a pressure of 15 - 30 MPa during solidification.

9. A metal heat-conducting material obtained by the preparation method of the metal heat-conducting material according to any one of claims 1 to 8.

10. A heat dissipation device, characterized in that, Comprising the metal heat-conducting material according to claim 9.

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