Liquid metal with high thermal conductivity and preparation process thereof

Abstract

The invention relates to a liquid metal with high thermal conductivity and a preparation process thereof, and relates to the field of metal materials, and preparation raw materials comprise the following components in parts by mass: 58-62 parts of indium, 8-10 parts of tin, 28-32 parts of bismuth and 4-6 parts of modified thermal conductive filler. The preparation method comprises the following steps: smelting indium, tin and bismuth in a protective atmosphere to obtain a metal mixed solution; the metal mixed liquid is cooled to 80-90 DEG C and poured into a mold, and solid metal is obtained after cooling; and heating and melting the solid metal to obtain liquid metal, adding the modified heat-conducting filler under a protective atmosphere, and performing stirring, ultrasonic treatment and vacuum defoaming to obtain the high-heat-conductivity liquid metal. The heat conduction performance of the material is improved, the leakage risk caused by excessive flowing of the material in the application process is reduced, and the use quality of the material is improved.

Description

Technical Field

[0001] This application relates to the field of metallic materials, and in particular to a liquid metal with high thermal conductivity and its preparation process. Background Technology

[0002] With the continuous development of modern industry and electronic technology, thermal management issues have become increasingly prominent. Highly efficient thermal interface materials are crucial for ensuring stable equipment operation and performance improvement. Liquid metal, as a material with unique thermal conductivity, is gradually emerging in the field of thermal management. Its high thermal conductivity enables rapid and efficient heat transfer, demonstrating enormous application potential in numerous fields such as electronic device heat dissipation and aerospace. It provides new solutions to heat dissipation challenges under complex operating conditions, driving technological progress in related industries.

[0003] In the past, the preparation of liquid metal thermal interface materials typically employed low-melting-point metals such as gallium, indium, tin, and bismuth, as well as their alloys. These alloys can remain liquid at room temperature or slightly higher temperatures while retaining the high thermal conductivity of the metals. The general preparation process involves smelting and other processes to obtain the desired alloy composition. However, in practical applications, to ensure the performance and quality of the materials, complex equipment and processes are often required. For example, some processes need to be performed under specific vacuum conditions, or chemical plating processes are used to improve the material's properties.

[0004] However, existing technologies have significant drawbacks. On the one hand, liquid metals suffer from excessive surface tension, which makes them prone to flow and leakage at high temperatures during use, severely affecting the quality of the liquid metal and thus requiring improvement. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a liquid metal with high thermal conductivity and its preparation process.

[0006] The present application provides a liquid metal with high thermal conductivity and its preparation process, which adopts the following technical solution: In a first aspect, this application provides a liquid metal with high thermal conductivity, employing the following technical solution: A liquid metal with high thermal conductivity is prepared from raw materials comprising the following components in parts by mass: 58-62 parts of indium 8-10 parts of tin 28-32 parts of bismuth 4-6 parts of modified thermally conductive filler; The modified thermally conductive filler is prepared using the following steps: The modifier is prepared into a modified liquid; the modified liquid and the thermally conductive filler are mixed, stirred, ultrasonicated, dried, ball-milled, and sieved to obtain the modified thermally conductive filler; The thermally conductive filler comprises micron-sized alumina and nano-sized zinc.

[0007] Nano-zinc, with its metallic properties, can form good interfacial contact with liquid metal matrices. The limited dissolution and interdiffusion on its surface help form a metallurgically bonded transition layer with gradually changing composition, thereby significantly reducing interfacial thermal resistance. This process enables nano-zinc to act as a highly efficient heat-conducting node, bridging dispersed micron-sized alumina particles and synergistically constructing a more complete and low-resistance three-dimensional heat-conducting network. At the same time, the surface modification treatment of the filler improves its wettability and dispersibility in the alloy melt, which helps the filler to be uniformly and stably distributed in the matrix. This optimized dispersion state not only endows the material with good thermal conductivity, but also moderately regulates the rheological properties of the system through particle interactions. This allows the material to maintain the necessary fluidity for construction and filling at the application temperature, while also possessing a certain degree of internal structure and shape retention, thereby reducing the risk of leakage due to excessive flow during operation and improving the practicality and reliability of the material.

[0008] Preferably, the mass ratio of micron-sized alumina to nano-sized zinc in the thermally conductive filler is 1:(0.25-0.4).

[0009] By limiting the mass ratio of micron-sized alumina to nano-sized zinc, their functions can be complementary and synergistic. Nano-zinc particles can be effectively distributed in the gaps and on the surface of micron-sized alumina. Through their good compatibility with the liquid metal matrix, they bridge multiple alumina particles, thereby constructing a denser and continuous three-dimensional thermally conductive network, effectively improving the thermal conductivity of the composite material. At the same time, this optimized ratio also helps to control the rheological behavior of the composite system. While endowing the material with high thermal conductivity, it maintains appropriate internal structural strength through the interaction between particles, so that the material maintains good morphological stability at the operating temperature, reduces the risk of leakage due to excessive fluidity, and thus improves the practical reliability of the material.

[0010] Preferably, the mass ratio of the thermally conductive filler to the modifier is 1:(0.01-0.02).

[0011] By optimizing the mass ratio of thermally conductive filler to modifier, the surface modification process can form a coating layer of suitable thickness on the filler surface. This coating layer effectively improves the interfacial compatibility between the filler and the liquid metal matrix, reduces interfacial thermal resistance, and thus facilitates heat transfer in the composite system, improving thermal conductivity. At the same time, the appropriate amount of modifier helps the filler particles achieve a good and stable dispersion in the matrix, reducing the abnormal increase in local viscosity caused by particle agglomeration. It also makes the rheological behavior of the entire material system more controllable at the operating temperature, thereby reducing the risk of leakage due to excessive material flow during application and improving the quality of material use.

[0012] Preferably, the modifier comprises hexadecyltrimethylammonium bromide and sorbitan oleate.

[0013] Hexadecyltrimethylammonium bromide improves the surface polarity of the filler through electrostatic adsorption, while the long-chain structure of sorbitan oleate provides steric stabilization. This composite modification helps the filler achieve a more uniform and stable dispersion in liquid metal, reducing particle agglomeration. On the one hand, it can reduce interfacial thermal resistance and promote heat transfer, which has a positive impact on improving thermal conductivity. On the other hand, it also makes the composite system have a more uniform internal structure, which helps maintain the material's appropriate viscosity and shape retention at operating temperatures, reducing the possibility of leakage due to excessive fluidity and improving the quality of the material.

[0014] Preferably, the mass ratio of hexadecyltrimethylammonium bromide to sorbitan oleate is 1:(1.4-1.8).

[0015] When compounded according to the above proportions, the modifier can more effectively synergistically modify the filler surface, promote its uniform dispersion in the liquid metal matrix, thereby reducing the thermal resistance caused by particle agglomeration, enabling the composite material to maintain good structural consistency at high temperatures, and improving the thermal conductivity and quality of use of the material.

[0016] Preferably, the modifier further includes 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane.

[0017] By introducing 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane, its hydrolysis allows it to form chemical bonds with the filler surface. The epoxy groups can interact with modifiers such as hexadecyltrimethylammonium bromide and sorbitan oleate that act on the filler surface, constructing a cross-linked and stable composite interface coating layer on the filler surface. This coating layer exhibits superior stability and integrity, effectively reducing the interfacial thermal resistance between the filler and the liquid metal matrix, and minimizing phonon scattering. This provides a more efficient path for heat transfer, further enhancing the thermal conductivity of the composite system. Simultaneously, this more stable interface layer also strengthens the dispersion stability and positioning retention of filler particles in the high-temperature melt, improving the uniformity of the internal structure and service reliability of the material, thereby reducing the risk of leakage during use.

[0018] Preferably, the mass ratio of hexadecyltrimethylammonium bromide, sorbitan oleate and 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane is 1:1.5:(0.3-0.4).

[0019] By synergistically controlling the mass ratio of the three modifier components, an effective balance is achieved between the electrostatic adsorption of hexadecyltrimethylammonium bromide, the steric stabilization of sorbitan oleate, and the chemical bonding of the silane coupling agent. This ratio helps to construct a denser and more stable composite coating layer on the filler surface, enhances its interfacial bonding with the metal matrix, reduces interfacial thermal resistance, thereby promoting the formation of thermal conduction pathways and improving the stability of the internal structure of the material.

[0020] Secondly, this application provides a process for preparing liquid metal with high thermal conductivity, employing the following technical solution: A process for preparing a liquid metal with high thermal conductivity includes the following steps: S1. Indium, tin and bismuth are melted under a protective atmosphere to obtain a metal mixture; S2. Cool the metal mixture to 80-90℃, pour it into a mold, and after cooling, obtain solid metal; S3. The solid metal is heated and melted to obtain liquid metal. Modified thermally conductive filler is added under a protective atmosphere. After stirring, ultrasonication, and vacuum degassing, a liquid metal with high thermal conductivity is obtained.

[0021] Melting alloy components under a protective atmosphere helps to obtain a metal matrix with uniform composition and few impurities. Preparing solid metal ingots first facilitates storage and transportation and ensures batch consistency as a standardized intermediate product. Subsequently, the solid metal is remelted under a protective atmosphere, and modified thermally conductive fillers are introduced into this liquid environment. Stirring and ultrasonic treatment promote uniform dispersion of the fillers, and vacuum degassing reduces internal defects, which helps the fillers build an effective thermally conductive network in the matrix. By improving the dispersion state and interfacial bonding, the composite material achieves good thermal conductivity while maintaining more stable rheological properties at the operating temperature, thus improving the quality of the material in use.

[0022] Preferably, the melting temperature in step S1 is 340-380℃, and the holding time is 2-3 hours.

[0023] A suitable combination of melting temperature and holding time helps ensure that the indium, tin, and bismuth components are fully melted and uniformly miscible, thereby obtaining an alloy matrix with uniform composition and structure. This provides a more stable environment for the subsequent dispersion of fillers, reduces thermal resistance caused by component segregation or the introduction of impurities, and improves thermal conductivity.

[0024] Preferably, in step S3, after vacuum degassing, a heat preservation and stirring process is performed. Under a protective atmosphere, the temperature is raised to 90-100℃, and the mixture is kept warm and stirred at a speed of 50-100 rpm for 30-60 minutes.

[0025] Performing heat preservation and stirring treatment under the above conditions helps to promote more complete interfacial bonding and molecular diffusion between the modified filler surface and the liquid metal matrix. This process can further optimize the interfacial structure, reduce interfacial defects, thereby reducing interfacial resistance during heat transfer and improving the thermal conductivity of the composite material. At the same time, this treatment also helps to relax and stabilize the internal structure of the composite material, making the distribution of dispersed filler particles in the matrix more stable. This helps the material maintain good rheological properties under working conditions, moderately enhances its shape retention ability, thereby reducing the tendency of excessive material flow and leakage due to viscosity decrease, and improving the quality of material use.

[0026] In summary, this application includes at least one of the following beneficial technical effects: Nano-zinc, with its metallic properties, can form good interfacial contact with liquid metal matrices. The limited dissolution and interdiffusion on its surface help form a metallurgically bonded transition layer with gradually changing composition, thereby significantly reducing interfacial thermal resistance. This process enables nano-zinc to act as a highly efficient heat-conducting node, bridging dispersed micron-sized alumina particles and synergistically constructing a more complete and low-resistance three-dimensional heat-conducting network. At the same time, the surface modification treatment of the filler improves its wettability and dispersibility in the alloy melt, which helps the filler to be uniformly and stably distributed in the matrix. This optimized dispersion state not only endows the material with good thermal conductivity, but also moderately regulates the rheological properties of the system through particle interactions. This allows the material to maintain the necessary fluidity for construction and filling at the application temperature, while also possessing a certain degree of internal structure and shape retention, thereby reducing the risk of leakage due to excessive flow during operation and improving the practicality and reliability of the material.

[0027] Hexadecyltrimethylammonium bromide improves the surface polarity of the filler through electrostatic adsorption, while the long-chain structure of sorbitan oleate provides steric stabilization. This composite modification helps the filler achieve a more uniform and stable dispersion in liquid metal, reducing particle agglomeration. On the one hand, it can reduce interfacial thermal resistance and promote heat transfer, which has a positive impact on improving thermal conductivity. On the other hand, it also makes the composite system have a more uniform internal structure, which helps maintain the material's appropriate viscosity and shape retention at operating temperatures, reducing the possibility of leakage due to excessive fluidity and improving the quality of the material.

[0028] By introducing 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane, its hydrolysis allows it to form chemical bonds with the filler surface. The epoxy groups can interact with modifiers such as hexadecyltrimethylammonium bromide and sorbitan oleate that act on the filler surface, constructing a cross-linked and stable composite interface coating layer on the filler surface. This coating layer exhibits superior stability and integrity, effectively reducing the interfacial thermal resistance between the filler and the liquid metal matrix, and minimizing phonon scattering. This provides a more efficient path for heat transfer, further enhancing the thermal conductivity of the composite system. Simultaneously, this more stable interface layer also strengthens the dispersion stability and positioning retention of filler particles in the high-temperature melt, improving the uniformity of the internal structure and service reliability of the material, thereby reducing the risk of leakage during use. Detailed Implementation

[0029] This application discloses a liquid metal with high thermal conductivity and its preparation process. Unless otherwise specified, all raw materials used in this application are commercially available. The following detailed description, in conjunction with embodiments, further illustrates this application: Raw material specifications: Micron-sized alumina with a particle size of 1-2μm was purchased from Huzhou Mister New Materials Co., Ltd.; nano zinc, model CW-Zn-001, was purchased from Shanghai Chaowei Nanotechnology Co., Ltd.; cetyltrimethylammonium bromide (CAS No.: 57-09-0); sorbitan oleate (CAS No.: 1338-43-8); indium, tin, and bismuth with a purity of over 99.99%; and 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane (CAS No.: 3388-04-3). Example 1

[0030] Preparation of modified thermally conductive fillers The thermally conductive filler is composed of micron-sized alumina and nano-sized zinc in a mass ratio of 1:0.25, and the modifier is composed of cetyltrimethylammonium bromide and sorbitan oleate in a mass ratio of 1:1.4. The mass ratio of the thermally conductive filler to the modifier is 1:0.01.

[0031] Cetyltrimethylammonium bromide and sorbitan oleate were added to anhydrous ethanol (solid content 2%) and stirred at 200 rpm for 30 min at 50 °C to obtain a modified liquid. The modified liquid was mixed with a thermally conductive filler and stirred at 300 rpm for 10 min. After sonication for 30 min, the mixture was vacuum dried at 60 °C, ball-milled, and passed through a 400-mesh sieve to obtain the modified thermally conductive filler.

[0032] Preparation of liquid metal with high thermal conductivity Weigh out 58 parts indium, 8 parts tin, 28 parts bismuth, and 4 parts modified thermally conductive filler.

[0033] S1. Indium, tin and bismuth are placed in an alumina crucible and melted in a high-temperature furnace under an argon protective atmosphere. The melting temperature is 340℃, the heating rate is 10℃ / min, and the holding time is 3h to obtain a metal mixture. S2. Cool the metal mixture to 90°C at a rate of 5°C / min, pour it out while hot, pour it into a mold, and after cooling, obtain solid metal; S3. Heat the solid metal to 90℃ to melt it into liquid metal. Under an argon protective atmosphere, add the modified thermally conductive filler in three batches. Stir at 500 rpm for 15 min, then stir at 8000 rpm for 25 min. Ultrasonically treat the mixture at 600W for 30 min, perform vacuum degassing, and stir at 50 rpm for 30 min at 80℃ and a vacuum of -0.095 MPa to obtain a liquid metal with high thermal conductivity. Example 2

[0034] Preparation of modified thermally conductive fillers The thermally conductive filler is composed of micron-sized alumina and nano-sized zinc in a mass ratio of 1:0.4, and the modifier is composed of cetyltrimethylammonium bromide and sorbitan oleate in a mass ratio of 1:1.8. The mass ratio of the thermally conductive filler to the modifier is 1:0.02.

[0035] Cetyltrimethylammonium bromide and sorbitan oleate were added to anhydrous ethanol (solid content 2%) and stirred at 200 rpm for 30 min at 50 °C to obtain a modified liquid. The modified liquid was mixed with a thermally conductive filler and stirred at 300 rpm for 10 min. After sonication for 30 min, the mixture was vacuum dried at 60 °C, ball-milled, and passed through a 400-mesh sieve to obtain the modified thermally conductive filler.

[0036] Preparation of liquid metal with high thermal conductivity Weigh out 62 parts indium, 10 parts tin, 32 parts bismuth, and 6 parts modified thermally conductive filler.

[0037] S1. Indium, tin and bismuth are placed in an alumina crucible and melted in a high-temperature furnace under an argon protective atmosphere. The melting temperature is 380℃, the heating rate is 10℃ / min, and the holding time is 2h to obtain a metal mixture. S2. Cool the metal mixture to 90°C at a rate of 5°C / min, pour it out while hot, pour it into a mold, and after cooling, obtain solid metal; S3. Heat the solid metal to 90℃ to melt it into liquid metal. Under an argon protective atmosphere, add the modified thermally conductive filler in three batches. Stir at 500 rpm for 15 min, then stir at 8000 rpm for 25 min. Ultrasonically treat the mixture at 600W for 30 min, perform vacuum degassing, and stir at 50 rpm for 30 min at 80℃ and a vacuum of -0.095 MPa to obtain a liquid metal with high thermal conductivity. Example 3

[0038] Preparation of modified thermally conductive fillers The thermally conductive filler is composed of micron-sized alumina and nano-sized zinc in a mass ratio of 1:0.325, and the modifier is composed of cetyltrimethylammonium bromide and sorbitan oleate in a mass ratio of 1:1.6. The mass ratio of the thermally conductive filler to the modifier is 1:0.015.

[0039] Cetyltrimethylammonium bromide and sorbitan oleate were added to anhydrous ethanol (solid content 2%) and stirred at 200 rpm for 30 min at 50 °C to obtain a modified liquid. The modified liquid was mixed with a thermally conductive filler and stirred at 300 rpm for 10 min. After sonication for 30 min, the mixture was vacuum dried at 60 °C, ball-milled, and passed through a 400-mesh sieve to obtain the modified thermally conductive filler.

[0040] Preparation of liquid metal with high thermal conductivity Weigh out 60 parts indium, 9 parts tin, 30 parts bismuth, and 5 parts modified thermally conductive filler.

[0041] S1. Indium, tin, and bismuth are placed in an alumina crucible and melted in a high-temperature furnace under an argon protective atmosphere. The melting temperature is 360℃, the heating rate is 10℃ / min, and the holding time is 2.5h to obtain a metal mixture. S2. Cool the metal mixture to 90°C at a rate of 5°C / min, pour it out while hot, pour it into a mold, and after cooling, obtain solid metal; S3. Heat the solid metal to 90℃ to melt it into liquid metal. Under an argon protective atmosphere, add the modified thermally conductive filler in three batches. Stir at 500 rpm for 15 min, then stir at 8000 rpm for 25 min. Ultrasonically treat the mixture at 600W for 30 min, perform vacuum degassing, and stir at 50 rpm for 30 min at 80℃ and a vacuum of -0.095 MPa to obtain a liquid metal with high thermal conductivity. Example 4

[0042] Example 4 is based on Example 3. The only difference between Example 4 and Example 3 is that the mass ratio of micron-sized alumina to nano-sized zinc in the thermally conductive filler in Example 4 is 1:0.15. Example 5

[0043] Example 5 is based on Example 3. The only difference between Example 5 and Example 3 is that the mass ratio of micron-sized alumina to nano-sized zinc in the thermally conductive filler in Example 5 is 1:0.5. Example 6

[0044] Example 6 is based on Example 3. The only difference between Example 6 and Example 3 is that the mass ratio of thermally conductive filler to modifier is 1:0.005 when the modified thermally conductive filler is prepared in Example 6. Example 7

[0045] Example 7 is based on Example 3. The only difference between Example 7 and Example 3 is that the mass ratio of thermally conductive filler to modifier is 1:0.025 when the modified thermally conductive filler is prepared in Example 7. Example 8

[0046] Example 8 is based on Example 3. The only difference between Example 8 and Example 3 is that in Example 8, the mass ratio of cetyltrimethylammonium bromide and sorbitan oleate in the modifier is 1:1.2 when preparing the modified thermally conductive filler. Example 9

[0047] Example 9 is based on Example 3. The only difference between Example 9 and Example 3 is that in Example 9, the mass ratio of hexadecyltrimethylammonium bromide and sorbitan oleate in the modifier is 1:2 when preparing the modified thermally conductive filler. Example 10

[0048] In Example 10, the modified thermally conductive filler also included 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane as a modifier.

[0049] Preparation of modified thermally conductive fillers The thermally conductive filler is composed of micron-sized alumina and nano-sized zinc in a mass ratio of 1:0.325. The modifier is composed of cetyltrimethylammonium bromide, sorbitan oleate and 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane in a mass ratio of 1:1.5:0.3. The mass ratio of the thermally conductive filler to the modifier is 1:0.015.

[0050] 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane was added to an aqueous ethanol solution (ethanol to water volume ratio 7:3, solid content 2%), and the pH was adjusted to 5 with glacial acetic acid. The solution was pre-hydrolyzed at 50°C for 30 min to obtain a silane hydrolysate. Hexadecyltrimethylammonium bromide and sorbitan oleate were added to anhydrous ethanol (solid content 2%), and the solution was stirred at 50°C at 200 rpm for 30 min to obtain a modified solution. A thermally conductive filler was added to the silane hydrolysate, and the solution was stirred at 500 rpm at 50°C for 60 min. After centrifugation and washing with anhydrous ethanol, a preliminary modified filler was obtained. The modified solution and the preliminary modified filler were mixed, stirred at 300 rpm for 10 min, sheared at 6000 rpm for 15 min, sonicated for 30 min, vacuum dried at 60°C, ball-milled, and passed through a 400-mesh sieve to obtain the modified thermally conductive filler. Example 11

[0051] Example 11 is based on Example 10. The only difference between Example 11 and Example 10 is that in Example 11, the modifier is composed of hexadecyltrimethylammonium bromide, sorbitan oleate and 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane in a mass ratio of 1:1.5:0.4. Example 12

[0052] Example 12 is based on Example 10. The only difference between Example 12 and Example 10 is that in Example 12, the modifier is composed of hexadecyltrimethylammonium bromide, sorbitan oleate and 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane in a mass ratio of 1:1.5:0.35. Example 13

[0053] Example 13 is based on Example 10. The only difference between Example 13 and Example 10 is that in Example 13, the modifier is composed of hexadecyltrimethylammonium bromide, sorbitan oleate and 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane in a mass ratio of 1:1.5:0.2. Example 14

[0054] Example 14 is based on Example 10. The only difference between Example 14 and Example 10 is that in Example 14, the modifier is composed of hexadecyltrimethylammonium bromide, sorbitan oleate and 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane in a mass ratio of 1:1.5:0.5. Example 15

[0055] Example 15 is based on Example 3. The only difference between Example 15 and Example 3 is that in Example 15, only hexadecyltrimethylammonium bromide is added as a modifier.

[0056] Preparation of modified thermally conductive fillers The thermally conductive filler is composed of micron-sized alumina and nano-sized zinc in a mass ratio of 1:0.325, and the modifier is hexadecyltrimethylammonium bromide. The mass ratio of the thermally conductive filler to the modifier is 1:0.015.

[0057] Cetyltrimethylammonium bromide was added to anhydrous ethanol (solid content 2%) and stirred at 200 rpm for 30 min at 50 °C to obtain a modified liquid. The modified liquid was mixed with the thermally conductive filler and stirred at 300 rpm for 10 min. After sonication for 30 min, it was vacuum dried at 60 °C, ball-milled, and passed through a 400-mesh sieve to obtain the modified thermally conductive filler. Example 16

[0058] Example 16 is based on Example 3. The only difference between Example 16 and Example 3 is that in Example 16, the melting temperature in step S1 is 300°C and the holding time is 3.5h. Example 17

[0059] Example 17 is based on Example 3. The only difference between Example 17 and Example 3 is that in Example 17, the melting temperature in step S1 is 420°C and the holding time is 1.5h. Example 18

[0060] Example 18 is based on Example 12. The only difference between Example 18 and Example 12 is that in step S3 of Example 18, after vacuum degassing, a heat preservation and stirring process is performed.

[0061] Preparation of liquid metal with high thermal conductivity Weigh out 60 parts indium, 9 parts tin, 30 parts bismuth, and 5 parts modified thermally conductive filler.

[0062] S1. Indium, tin, and bismuth are placed in an alumina crucible and melted in a high-temperature furnace under an argon protective atmosphere. The melting temperature is 360℃, the heating rate is 10℃ / min, and the holding time is 2.5h to obtain a metal mixture. S2. Cool the metal mixture to 90°C at a rate of 5°C / min, pour it out while hot, pour it into a mold, and after cooling, obtain solid metal; S3. Heat the solid metal to 90℃ to melt it into liquid metal. Under an argon protective atmosphere, add the modified thermally conductive filler in three batches. Stir at 500 rpm for 15 minutes, then stir at 8000 rpm for 25 minutes. Ultrasonically treat at 600W for 30 minutes, then perform vacuum degassing treatment. Stir at 50 rpm for 30 minutes at 80℃ and a vacuum of -0.095MPa, then perform heat preservation and stirring treatment. Under an argon protective atmosphere, heat to 90℃ and stir at 100 rpm for 60 minutes to obtain a liquid metal with high thermal conductivity. Example 19

[0063] Example 19 is based on Example 18. The only difference between Example 19 and Example 18 is that the heat preservation and stirring conditions in step S3 of Example 19 are: heat up to 100°C and keep warm and stir at 50 rpm for 30 min. Example 20

[0064] Example 20 is based on Example 18. The only difference between Example 20 and Example 18 is that the heat preservation and stirring conditions in step S3 of Example 20 are: heating to 95°C and stirring at 75 rpm for 45 min.

[0065] Comparative Example 1 Comparative Example 1 is based on Example 3. The only difference between Comparative Example 1 and Example 3 is that the modified thermally conductive filler is replaced with a thermally conductive filler in Comparative Example 1.

[0066] Preparation of liquid metal with high thermal conductivity Weigh out 60 parts indium, 9 parts tin, 30 parts bismuth, and 5 parts thermally conductive filler. The thermally conductive filler is composed of micron-sized alumina and nano-zinc in a mass ratio of 1:0.325.

[0067] S1. Indium, tin, and bismuth are placed in an alumina crucible and melted in a high-temperature furnace under an argon protective atmosphere. The melting temperature is 360℃, the heating rate is 10℃ / min, and the holding time is 2.5h to obtain a metal mixture. S2. Cool the metal mixture to 90°C at a rate of 5°C / min, pour it out while hot, pour it into a mold, and after cooling, obtain solid metal; S3. Heat the solid metal to 90℃ to melt it into liquid metal. Under an argon protective atmosphere, add the thermally conductive filler in three batches. Stir at 500 rpm for 15 minutes, then stir at 8000 rpm for 25 minutes. Ultrasonically treat the mixture at 600W for 30 minutes, perform vacuum degassing, and stir at 50 rpm for 30 minutes at 80℃ and a vacuum of -0.095MPa to obtain a liquid metal with high thermal conductivity.

[0068] Comparative Example 2 Comparative Example 2 is based on Example 3. The only difference between Comparative Example 2 and Example 3 is that no nano zinc is added to the thermally conductive filler in Comparative Example 2.

[0069] Preparation of modified thermally conductive fillers The thermally conductive filler is micron-sized alumina, and the modifier consists of cetyltrimethylammonium bromide and sorbitan oleate in a mass ratio of 1:1.6. The mass ratio of the thermally conductive filler to the modifier is 1:0.015.

[0070] Cetyltrimethylammonium bromide and sorbitan oleate were added to anhydrous ethanol (solid content 2%) and stirred at 200 rpm for 30 min at 50 °C to obtain a modified liquid. The modified liquid was mixed with a thermally conductive filler and stirred at 300 rpm for 10 min. After sonication for 30 min, the mixture was vacuum dried at 60 °C, ball-milled, and passed through a 400-mesh sieve to obtain the modified thermally conductive filler.

[0071] Preparation of liquid metal with high thermal conductivity Weigh out 60 parts indium, 9 parts tin, 30 parts bismuth, and 5 parts modified thermally conductive filler.

[0072] S1. Indium, tin, and bismuth are placed in an alumina crucible and melted in a high-temperature furnace under an argon protective atmosphere. The melting temperature is 360℃, the heating rate is 10℃ / min, and the holding time is 2.5h to obtain a metal mixture. S2. Cool the metal mixture to 90°C at a rate of 5°C / min, pour it out while hot, pour it into a mold, and after cooling, obtain solid metal; S3. Heat the solid metal to 90℃ to melt it into liquid metal. Under an argon protective atmosphere, add the modified thermally conductive filler in three batches. Stir at 500 rpm for 15 min, then stir at 8000 rpm for 25 min. Ultrasonically treat the mixture at 600W for 30 min, perform vacuum degassing, and stir at 50 rpm for 30 min at 80℃ and a vacuum of -0.095 MPa to obtain a liquid metal with high thermal conductivity. Performance testing experiment

[0073] (1) Thermal resistance test: The sample is injected into a cylindrical mold with an inner diameter of 25 mm and a height of 1.0 mm. After cooling, it is prepared into a metal sheet sample with a thickness of 1.0 mm and a diameter of 25 mm. At the same time, a 99.99% pure indium sheet with the same shape and size is prepared as a reference sample. The test stack is constructed from top to bottom, consisting of a heating block (set temperature 90℃), an upper test sample, a central copper pillar (20 mm high, with temperature measuring points T2 and T3 at the midpoint and 2 mm from both ends respectively), a lower test sample (pure indium sheet), and a water-cooled radiator (set temperature 20℃). A constant pressure of 0.34 MPa is applied to the entire stack through a screw. The calibration test is performed by installing pure indium sheets on both the upper and lower samples. When the system reaches thermal steady state, the input power Q and the temperatures T2 and T3 are recorded. Then, under the same heating power Q and pressure conditions, only the upper sample is replaced with the test sample. The system is waited to reach the same steady state conditions again, and the new temperatures T2' and T3' are recorded. The temperature difference ΔT of the reference sample is calculated. ref =T2-T3 and the temperature difference ΔT of the sample to be tested test =T2'-T3', the thermal conductivity λ of pure indium at 90℃ refThe thermal resistance is 86 W / (m·K). ref =L / λS, where L is the sample thickness and S is the sample area, calculate the thermal resistance R of the sample. test =(ΔT test / ΔT ref The result of )×R_ref is recorded in Table 1.

[0074] (2) Select GB / T 41079.3-2024 Determination of physical properties of liquid metals - Part 3: Determination of viscosity as the standard, and test the viscosity of the sample at 90℃. Each sample is tested three times, and the average value is taken after measurement. The results are recorded in Table 1.

[0075] Table 1. Test results of thermal conductivity and viscosity Test results Thermal resistance (K / W) Viscosity (mPa·s) Example 1 0.0452 842 Example 2 0.0440 925 Example 3 0.0447 887 Example 4 0.0466 852 Example 5 0.0454 949 Example 6 0.0465 954 Example 7 0.0460 873 Example 8 0.0457 884 Example 9 0.0456 889 Example 10 0.0430 850 Example 11 0.0428 843 Example 12 0.0427 842 Example 13 0.0439 867 Example 14 0.0442 845 Example 15 0.0475 955 Example 16 0.0463 892 Example 17 0.0457 877 Example 18 0.0424 885 Example 19 0.0420 878 Example 20 0.0421 883 Comparative Example 1 0.0506 1022 Comparative Example 2 0.0526 814 As shown in Table 1, the thermal resistance of Examples 1-3 is less than 0.0452 K / W, and the viscosity is between 842-925 mPa·s. This indicates that the material prepared in this application has good thermal conductivity and controllable flowability, which provides a guarantee for reducing the risk of leakage in thermal interface applications.

[0076] As shown in Table 1, the differences between Examples 4-9 and Example 3 are only as follows: in Examples 4 and 5, the compounding ratio of the thermally conductive filler was changed, affecting the balance of performance between the two fillers; in Examples 6 and 7, too little modifier affected dispersibility, and too much affected thermal resistance, thus reducing performance; in Examples 8 and 9, the compounding ratio of the modifier was changed, affecting the dispersion effect and reducing thermal conductivity.

[0077] As shown in Table 1, the only difference between Examples 10-15 and Example 3 is that: in Examples 10-12, 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane was added in a specified ratio to form a compound modifier, which crosslinked the surface modified layer internally, reduced the interfacial thermal resistance, and improved the performance; Examples 13 and 14 deviated from the specified ratio, and the performance improvement effect decreased; Example 15 used only hexadecyltrimethylammonium bromide as a single modifier, which reduced the dispersibility and significantly decreased the performance.

[0078] As shown in Table 1, the only difference between Examples 16 and 17 and Example 3 is that the limited melting conditions were changed in Examples 16 and 17. Too low a temperature may cause uneven dispersion of alloying elements, while too high a temperature may cause element burn-off and volatilization, introduce defects, and reduce performance.

[0079] As shown in Table 1, Examples 18-20 further optimized the post-processing process based on Example 12, performing heat preservation and stirring treatment after vacuum degassing to promote homogenization and improve the performance of the material.

[0080] As shown in Table 1, the only difference between Comparative Example 1 and Example 3 is that the thermally conductive filler in Comparative Example 1 was not modified, resulting in decreased dispersibility, weakened interfacial bonding, significantly reduced thermal conductivity, and increased viscosity.

[0081] As shown in Table 1, the only difference between Comparative Example 2 and Example 3 is that no nano zinc was added in Comparative Example 2, which destroyed the synergistic effect of micron-sized aluminum and nano zinc, resulting in the absence of thermal bridges and a significant decrease in performance.

[0082] This specific embodiment is merely an explanation of this application and is not intended to limit it. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification but must be determined according to the scope of the claims.

Claims

1. A liquid metal with high thermal conductivity, characterized in that: The raw materials for preparation include the following components in parts by weight: 58-62 parts of indium 8-10 parts of tin 28-32 parts of bismuth 4-6 parts of modified thermally conductive filler; The modified thermally conductive filler is prepared using the following steps: The modifier is prepared into a modified liquid; the modified liquid and the thermally conductive filler are mixed, stirred, ultrasonicated, dried, ball-milled, and sieved to obtain the modified thermally conductive filler; The thermally conductive filler comprises micron-sized alumina and nano-sized zinc.

2. The liquid metal with high thermal conductivity according to claim 1, characterized in that: The mass ratio of micron-sized alumina to nano-sized zinc in the thermally conductive filler is 1:(0.25-0.4).

3. A liquid metal with high thermal conductivity according to claim 2, characterized in that: The mass ratio of the thermally conductive filler to the modifier is 1:(0.01-0.02).

4. A liquid metal with high thermal conductivity according to claim 3, characterized in that: The modifiers include hexadecyltrimethylammonium bromide and sorbitan oleate.

5. A liquid metal with high thermal conductivity according to claim 4, characterized in that: The mass ratio of hexadecyltrimethylammonium bromide to sorbitan oleate is 1:(1.4-1.8).

6. A liquid metal with high thermal conductivity according to claim 5, characterized in that: The modifier also includes 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane.

7. A liquid metal with high thermal conductivity according to claim 6, characterized in that: The mass ratio of hexadecyltrimethylammonium bromide, sorbitan oleate, and 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane is 1:1.5:(0.3-0.4).

8. A process for preparing a liquid metal with high thermal conductivity as described in any one of claims 1-7, characterized in that: Includes the following steps: S1. Indium, tin and bismuth are melted under a protective atmosphere to obtain a metal mixture; S2. Cool the metal mixture to 80-90℃, pour it into a mold, and after cooling, obtain solid metal; S3. The solid metal is heated and melted to obtain liquid metal. Modified thermally conductive filler is added under a protective atmosphere. After stirring, ultrasonication, and vacuum degassing, a liquid metal with high thermal conductivity is obtained.

9. The preparation process of liquid metal with high thermal conductivity according to claim 8, characterized in that: In step S1, the melting temperature is 340-380℃ and the holding time is 2-3 hours.

10. The preparation process of liquid metal with high thermal conductivity according to claim 8, characterized in that: In step S3, after vacuum degassing, a heat preservation and stirring process is performed. Under a protective atmosphere, the temperature is raised to 90-100℃ and stirred at a speed of 50-100 rpm for 30-60 minutes.