Carbon-coated liquid metal material and preparation method thereof

Abstract

The application discloses a kind of carbon-coated liquid metal materials and preparation method thereof, the material includes the following weight parts of raw materials: gallium 0-90 parts, bismuth 0-35 parts, indium 10-55 parts, tin 0-20 parts, carbon powder 0.1-0.5 parts.The application utilizes carbon material powder to directly coat liquid metal particles, effectively solves the problem of poor wettability of liquid metal on carbon base, eliminates the dependence on metal intermediate transition layer in traditional technology, substantially reduces the contact thermal resistance, can significantly improve the heat transfer efficiency between interfaces;And trace carbon material is introduced in liquid metal, the viscosity of material is moderately improved, the rheological property is improved, not only the filling capacity of material to rough surface is enhanced, but also the excessive flow and pump-out effect of liquid metal in molten state are effectively prevented, the reliability and safety of long-term use are improved.

Description

Technical Field

[0001] This invention belongs to the field of thermal conductive materials technology, and specifically relates to a carbon-coated liquid metal material and its preparation method. Background Technology

[0002] With the rapid development of modern electronic information technology, electronic components are constantly evolving towards high performance, high integration, miniaturization, and lightweight design. While this trend brings superior computing power and portability, it also leads to a sharp increase in chip power consumption and heat flux density. Efficient thermal management has become a key bottleneck in ensuring the stable operation of electronic devices and extending their service life. Statistics show that more than 55% of electronic device failures are directly related to overheating. Therefore, how to quickly and efficiently conduct the heat generated by the chip to the heat sink is a core challenge in the field of thermal interface materials. Currently, traditional thermal interface materials such as silicone grease and thermal pads, although technologically mature and low-cost, generally have low thermal conductivity, typically less than 10 W / (m·K), which is insufficient to meet the heat dissipation requirements of next-generation high-power chips. Against this backdrop, liquid metals, represented by gallium-based and bismuth-based alloys, are considered ideal choices for next-generation high-performance thermal interface materials due to their liquid state at room temperature or near room temperature, extremely high thermal conductivity, and excellent deformation filling ability. Liquid metals can effectively fill the micron-level gaps between the chip and the heat sink caused by surface roughness, significantly reducing contact thermal resistance.

[0003] However, in practical applications, using liquid metal solely as a thermal interface material still presents several unresolved technical challenges. First, liquid metals have poor affinity with carbon-based materials, resulting in high interfacial thermal resistance. To achieve optimal heat dissipation performance, highly thermally conductive carbon-based materials such as graphene and pyrolytic graphite are widely used as heat spreaders or heat dissipation substrates. However, liquid metals have extremely high surface tension and poor wettability on non-metallic surfaces such as carbon materials, making direct spreading and bonding difficult. This leads to significant interfacial thermal resistance between the liquid metal and the carbon-based heat dissipation material, severely limiting the efficiency of the overall heat dissipation system. In existing technologies, to address this issue, a metal layer is typically deposited on the carbon material surface as an intermediate transition layer to enhance the adhesion of the liquid metal. However, this method not only increases process complexity and cost, but the introduced additional metal layer itself becomes a new source of thermal resistance, failing to maximize the utilization of the ultra-high thermal conductivity of both liquid metal and carbon materials. Second, the excessive fluidity of liquid metals poses risks of pumping out and migration. Liquid metal remains completely liquid at operating temperatures. Its low viscosity makes it highly susceptible to being "pumped out" from the interface when the chip and heatsink undergo minor deformations or vibrations due to thermal expansion and contraction. This can lead to material loss, contamination of surrounding circuits, and even short-circuit risks. Furthermore, its high fluidity makes it difficult to stably fill large assembly gaps. Finally, existing technologies struggle to balance high thermal conductivity with structural stability. Existing modification methods, such as adding metal or ceramic particles, while increasing viscosity to some extent, often sacrifice overall thermal conductivity or fail to fundamentally improve the interfacial bonding between the liquid metal and the carbon substrate. Therefore, developing a novel liquid metal composite material that achieves good affinity with carbon-based materials, reduces interfacial thermal resistance, maintains high thermal conductivity, and possesses suitable viscosity and structural stability is an urgent and valuable research topic in the field of electronic thermal management. This invention aims to provide an innovative solution based on this background.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a carbon-coated liquid metal material and its preparation method, thereby overcoming the defects in the prior art.

[0006] To achieve the above objectives, the present invention provides a carbon-coated liquid metal material comprising the following raw materials in parts by weight: gallium 0-90 parts, bismuth 0-35 parts, indium 10-55 parts, tin 0-20 parts, and carbon powder 0.1-0.5 parts.

[0007] Preferably, the carbon-coated liquid metal material comprises the following raw materials in parts by weight: 60-90 parts gallium, 10-25 parts indium, 0-20 parts tin, and 0.1-0.5 parts carbon powder.

[0008] Preferably, the carbon-coated liquid metal material comprises the following raw materials in parts by weight: 30-35 parts bismuth, 45-55 parts indium, 0-20 parts tin, and 0.1-0.5 parts carbon powder.

[0009] Preferably, the carbon powder is one or a mixture of more than one of graphene, carbon nanotubes, fullerene C60, diamond, and nano-carbon.

[0010] Preferably, the carbon powder has a particle size of 100-150 nm and a purity of 99.99%.

[0011] This invention also provides a method for preparing carbon-coated liquid metal materials, comprising the following steps: S1: Weigh solid gallium, solid bismuth, solid indium, solid tin, carbon material powder, polyvinylpyrrolidone, and anhydrous ethanol as raw materials according to the mass ratio; S2: Solid gallium, solid bismuth, solid indium, and solid tin are placed together in a quartz crucible. The crucible is then placed in a vacuum oven and kept at 300°C. During the heat preservation process, the materials are mixed evenly. After natural cooling, liquid metal material is obtained. S3: Weigh the liquid metal material obtained in step S2 with polyvinylpyrrolidone and anhydrous ethanol according to the proportion, put them into a container and perform ultrasonication to disperse them into micron-sized droplets. S4: Ozone treatment is performed on carbon material powder, followed by ultrasonication with anhydrous ethanol to form a dispersion. S5: Ultrasonically mix the micron-sized droplets obtained in S3 with the carbon material dispersion obtained in S4; S6: The mixture obtained in S5 is placed in a vacuum oven for drying to obtain carbon-coated liquid metal material.

[0012] Preferably, in step S2, the temperature is increased to 300°C at a heating rate of 3-8°C / min, and the holding time is 90-120min.

[0013] Preferably, in step S3, the mass ratio of the liquid metal material to polyvinylpyrrolidone and anhydrous ethanol is 10:4:50-70.

[0014] Preferably, in step S4, the ozone concentration is 80-120 ppm, the flow rate is 1.5-2.5 L / min, the ozone treatment temperature is 70-100℃, and the treatment time is 15-25 min.

[0015] Preferably, the temperature of the ultrasonic treatment in step S4 is 80-100℃, and the treatment time is 10-30 min.

[0016] Compared with the prior art, one aspect of the present invention has the following beneficial effects: (1) The present invention utilizes carbon material powder to directly coat liquid metal particles, which effectively solves the problem of poor wettability of liquid metal on carbon substrate, eliminates the dependence on the intermediate metal transition layer in traditional technology, greatly reduces contact thermal resistance, and can significantly improve the heat transfer efficiency between interfaces. (2) By introducing trace amounts of carbon material into liquid metal, the present invention moderately increases the viscosity of the material and improves its rheological properties. This not only enhances the material's ability to fill rough surfaces, but also effectively prevents excessive flow and pumping effect of liquid metal in the molten state, thereby improving the reliability and safety of long-term use. (3) The present invention adopts a preparation process of ozone treatment combined with ultrasonic dispersion. By introducing oxygen-containing functional groups, the dispersibility of carbon materials is improved. There is no need for complicated chemical plating or high-temperature sintering steps. The reaction conditions are mild, the operation is simple, the cost is low, and it is environmentally friendly, which has great prospects for industrial application. Attached Figure Description

[0017] Figure 1 This is a magnified microscopic view of carbon-coated liquid metal particles in Embodiment 2 of the present invention; Figure 2 This is a magnified microscopic view of the sample particles in Comparative Example 6 of the present invention; Figure 3 This is an image of a sample coated on a graphite sheet according to Example 2 of the present invention; Figure 4 This is an image of the sample of Comparative Example 6 of the present invention coated on a graphite sheet. Detailed Implementation

[0018] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0019] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0020] Example 1:

[0021] A method for preparing carbon-coated liquid metal materials includes the following steps: S1: Weigh out 68.5g of solid gallium, 21.5g of solid indium and 10g of solid tin for later use; S2: Solid gallium, solid indium, and solid tin are placed together in a quartz crucible. The crucible is placed in a vacuum oven and kept at 300℃ for 2 hours. The heating rate is 3-8℃ / min. During the holding process, the materials are mixed evenly. After natural cooling, gallium indium tin liquid metal material is obtained. S3: Mix the liquid metal material obtained in step S2 with 40g of polyvinylpyrrolidone (PVP) and 500g of anhydrous ethanol, and place it in a container for ultrasonication. The ultrasonication temperature is 20-30℃, the ultrasonication time is 10-60min, and the ultrasonication is repeated three times to disperse the liquid metal into micron-sized droplets. S4: Weigh 0.1g of graphene and treat it with ozone at a concentration of 100ppm, a flow rate of 2L / min, a temperature of 80℃, and a time of 20min. Then add 10g of anhydrous ethanol and sonicate at a temperature of 20-30℃ for 10-60min, repeating the sonication three times. S5: The micron-sized droplets obtained in S3 are ultrasonically mixed with the carbon material dispersion obtained in S4. The ultrasonic temperature is 80-100℃, the ultrasonic time is 10-30 min, and the ultrasonication is repeated three times. S6: Place the mixture obtained in S5 into a vacuum oven and dry it at 60°C for 2 hours to obtain carbon-coated liquid metal material.

[0022] The thermal conductivity of the gallium-based liquid metal composite carbon material was measured, and the thermal conductivity coefficient was 92 W / (m·K).

[0023] Example 2:

[0024] The difference from Example 1 is that the amount of graphene in step S4 is 0.3g.

[0025] The thermal conductivity of the gallium-based liquid metal composite carbon material was measured, and the thermal conductivity coefficient was 97 W / (m·K).

[0026] Example 3:

[0027] The difference from Example 1 is that the amount of graphene in step S4 is 0.5g.

[0028] The thermal conductivity of the gallium-based liquid metal composite carbon material was measured, and the thermal conductivity coefficient was 96 W / (m·K).

[0029] Example 4

[0030] A method for preparing carbon-coated bismuth-based liquid metal materials includes the following steps: S1: Weigh out 32.5g of solid bismuth, 51g of solid indium and 16.5g of solid tin for later use; S2: Solid bismuth, solid indium, and solid tin are placed together in a quartz crucible. The crucible is placed in a vacuum oven and kept at 300℃ for 2 hours. The heating rate is 3-8℃ / min. During the holding process, the materials are mixed evenly. After natural cooling, bismuth-indium-tin liquid metal material is obtained. S3: Mix the liquid metal material obtained in step S2 with 40g of polyvinylpyrrolidone (PVP) and 500g of anhydrous ethanol, and place it in a container for ultrasonication. The ultrasonication temperature is 80-100℃, the ultrasonication time is 10-30min, and the ultrasonication is repeated three times to disperse the liquid metal into micron-sized droplets. S4: Weigh 0.3g of graphene and treat it with ozone at a concentration of 100ppm, a flow rate of 2L / min, a temperature of 80℃, and a time of 20min. Then add 10g of anhydrous ethanol and sonicate at a temperature of 20-30℃ for 10-60min, repeating the sonication three times. S5: The micron-sized droplets obtained in S3 are ultrasonically mixed with the carbon material dispersion obtained in S4. The ultrasonic temperature is 80-100℃, the ultrasonic time is 10-30 min, and the ultrasonication is repeated three times. S6: Place the mixture obtained in S5 into a vacuum oven and dry it at 60°C for 2 hours to obtain carbon-coated liquid metal material.

[0031] The thermal conductivity of the bismuth-based liquid metal composite carbon material was measured, and the thermal conductivity coefficient was 78 W / (m·K).

[0032] Comparative Example 1 Unlike Example 1, the amount of graphene in step S4 is 0.05g.

[0033] The thermal conductivity of the gallium-based liquid metal composite carbon material was measured, and the thermal conductivity coefficient was 89 W / (m·K).

[0034] Comparative Example 2 The difference from Example 1 is that the amount of graphene in step S4 is 0.6g.

[0035] The thermal conductivity of the gallium-based liquid metal composite carbon material was measured, and the thermal conductivity coefficient was 87 W / (m·K).

[0036] Comparative Example 3 The difference from Example 1 is that the amount of graphene in step S4 is 0.8g.

[0037] The thermal conductivity of the gallium-based liquid metal composite carbon material was measured, and the thermal conductivity coefficient was 78 W / (m·K).

[0038] Comparative Example 4: Unlike Example 1, the carbon material used in step S4 is carbon nanotubes.

[0039] The thermal conductivity of the gallium-based liquid metal composite carbon material was measured, and the thermal conductivity coefficient was 94 W / (m·K).

[0040] Comparative Example 5: Unlike Example 1, the carbon material used in step S4 is fullerene C60.

[0041] The thermal conductivity of the gallium-based liquid metal composite carbon material was measured, and the thermal conductivity coefficient was 90 W / (m·K).

[0042] Comparative Example 6: Unlike Example 1, the graphene in step S4 was not treated with ozone.

[0043] The thermal conductivity of the gallium-based liquid metal composite carbon material was measured, and the thermal conductivity was 61 W / (m·K). The carbon-coated liquid metal materials obtained in Examples 1-5 were subjected to various performance tests. The test methods and results are shown in Table 1.

[0044] The carbon-coated liquid metal materials obtained in Comparative Examples 1-4 were subjected to various performance tests. The test methods and results are shown in Table 2.

[0045] The testing method is as follows: Using graphite sheets with a thickness of 0.2 mm and a diameter of 30 mm as raw materials, both sides of the graphite sheets were coated with the liquid metal composite material of the above embodiment (such as coating both sides with the material of Example 1, and so on), and the thermal resistance of the samples was tested. The blank group used graphite sheets with a thickness of 0.2 mm and a diameter of 30 mm as raw materials, without any treatment on either side, and tested the thermal resistance of the samples.

[0046] The test results above show that: From the perspective of thermal conductivity, the thermal conductivity of the samples in Examples 1-3, as well as Comparative Examples 4 and 5, is ≥90 W / (m·K), indicating that when the carbon material addition amount is 0.1-0.5%, the carbon-coated liquid metal materials prepared all exhibit good thermal conductivity. Comparative Examples 4 and 5 show that changes in the morphology of the carbon material do not significantly affect the thermal conductivity. However, the results of Comparative Example 6 show that if the carbon material powder is not treated with ozone, the thermal resistance increases significantly and the thermal conductivity decreases considerably after the sample is combined with the carbon-based material.

[0047] From the perspective of coating effect, magnified schematic diagrams of the samples of Example 2 and Comparative Example 6 under a microscope are shown below. Figure 1, 2 As shown, the ozone-treated carbon powder is uniformly coated on the surface of the liquid metal particles. The effects of coating the samples of Example 2 and Comparative Example 6 on graphite sheets are illustrated in the following figures. Figure 3 , 4 As shown, the carbon powder coated on the surface of liquid metal particles effectively solves the problem of poor wettability of liquid metal on carbon substrates, and to a certain extent increases the viscosity of liquid metal, allowing it to be uniformly coated on the surface of carbon materials. This effectively reduces interfacial thermal resistance and improves the reliability and safety of its use.

[0048] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A carbon-coated liquid metal material, characterized in that, The raw materials include the following parts by weight: gallium 0-90 parts, bismuth 0-35 parts, indium 10-55 parts, tin 0-20 parts, and carbon powder 0.1-0.5 parts.

2. The carbon-coated liquid metal material according to claim 1, characterized in that, It includes the following raw materials in parts by weight: 60-90 parts gallium, 10-25 parts indium, 0-20 parts tin, and 0.1-0.5 parts carbon powder.

3. The carbon-coated liquid metal material according to claim 1, characterized in that, The raw materials include the following parts by weight: 30-35 parts bismuth, 45-55 parts indium, 0-20 parts tin, and 0.1-0.5 parts carbon powder.

4. The carbon-coated liquid metal material according to claim 1, characterized in that, The carbon powder is one or a mixture of more than one of graphene, carbon nanotubes, fullerene C60, diamond, and nano-carbon.

5. The carbon-coated liquid metal material according to claim 1, characterized in that, The carbon powder has a particle size of 100-150 nm and a purity of 99.99%.

6. A method for preparing the carbon-coated liquid metal material according to any one of claims 1-5, characterized in that, Includes the following steps: S1: Weigh solid gallium, solid bismuth, solid indium, solid tin, carbon material powder, polyvinylpyrrolidone, and anhydrous ethanol as raw materials according to the mass ratio; S2: Solid gallium, solid bismuth, solid indium, and solid tin are placed together in a quartz crucible. The crucible is then placed in a vacuum oven and kept at 300°C. During the heat preservation process, the materials are mixed evenly. After natural cooling, liquid metal material is obtained. S3: Weigh the liquid metal material obtained in step S2 with polyvinylpyrrolidone and anhydrous ethanol according to the proportion, put them into a container and perform ultrasonication to disperse them into micron-sized droplets. S4: Ozone treatment is performed on carbon material powder, followed by ultrasonication with anhydrous ethanol to form a dispersion. S5: Ultrasonically mix the micron-sized droplets obtained in S3 with the carbon material dispersion obtained in S4; S6: The mixture obtained in S5 is placed in a vacuum oven for drying to obtain carbon-coated liquid metal material.

7. The method for preparing carbon-coated liquid metal materials according to claim 6, characterized in that, In step S2, the temperature is increased to 300℃ at a heating rate of 3-8℃ / min, and the holding time is 90-120min.

8. The method for preparing carbon-coated liquid metal materials according to claim 6, characterized in that, In step S3, the mass ratio of liquid metal material to polyvinylpyrrolidone and anhydrous ethanol is 10:4:50-70.

9. The method for preparing carbon-coated liquid metal materials according to claim 6, characterized in that, In step S4, the ozone concentration during ozone treatment is 80-120 ppm, the flow rate is 1.5-2.5 L / min, the ozone treatment temperature is 70-100℃, and the treatment time is 15-25 min.

10. The method for preparing carbon-coated liquid metal materials according to claim 6, characterized in that, The ultrasonic treatment in step S4 is performed at a temperature of 80-100℃ for 10-30 minutes.

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