Metallized diamond particle, diamond / gallium-based liquid metal composite material and preparation method thereof

Abstract

The invention discloses a metalized diamond particle, a diamond / gallium-based liquid metal composite material and a preparation method thereof, and belongs to the field of composite thermal interface materials. The metallized diamond particle comprises a diamond particle, the surface of the diamond particle is coated with an immiscible alloy layer, the immiscible alloy layer contains a diffusion barrier component and a reaction wetting component, and the content of the diffusion barrier component in the immiscible alloy layer is not higher than 15 at% of the total content of the diffusion barrier component and the reaction wetting component; wherein the diffusion barrier component is one or more of tungsten, molybdenum and tantalum, and the reaction wetting component is one or more of silver and copper. The metallized diamond particles and the gallium-based liquid metal are combined to form the composite material, so that the diamond / gallium-based liquid metal composite material has more excellent thermal conductivity.

Description

Technical Field

[0001] This invention relates to metallized diamond particles, diamond / gallium-based liquid metal composite materials and their preparation methods, belonging to the field of thermal interface materials. Background Technology

[0002] As electronic devices continue to evolve towards miniaturization, multifunctionality, and high integration, their power density during operation has significantly increased, placing higher demands on heat dissipation. Thermal interface materials, by filling the gap between the heat source and the heat sink, create efficient heat transfer channels, thereby reducing interfacial thermal resistance and achieving efficient heat dissipation.

[0003] Among numerous thermal interface materials, gallium-based liquid metals have attracted considerable attention due to their unique physicochemical properties. They are liquid at room temperature and possess excellent thermal conductivity and superior fluidity, making them a hot material in the field of thermal management for high-performance electronic devices. However, current technologies still face bottlenecks such as the easy oxidation of liquid metals, poor bonding with other thermally conductive components, and insufficient operational stability, necessitating breakthroughs through interface composition and structural design.

[0004] Diamond, as the material with the best known thermal conductivity in nature, has a thermal conductivity of 2000-2200 W·m at room temperature. -1 ·K -1 Meanwhile, diamond possesses an extremely low coefficient of thermal expansion, making it an ideal thermal management material. Composite thermally conductive materials using gallium-based liquid metal as the substrate and diamond as the filler have attracted widespread attention in recent years. However, this combination has some significant drawbacks. The most significant problem is that diamond has extremely high chemical inertness, exhibiting very poor wettability when mixed with most metals, including liquid metals, resulting in very weak interfacial adhesion. This makes it difficult for gallium-based liquid metal to spread and adhere directly to the diamond surface. Physical adhesion of diamond particles requires the use of oxides on the gallium-based liquid metal surface. However, due to the low thermal conductivity and weak adhesion of this oxide film to diamond, the diamond filler cannot fully utilize its thermal conductivity enhancement performance.

[0005] Currently, in practical applications, surface metallization treatment is typically performed on the diamond surface to enhance its surface activity and wettability, thereby strengthening interfacial bonding and fully leveraging the beneficial effect of diamond on the thermal conductivity of composite materials. Patents and literature have reported on metallization treatments of diamond using single-layer or double-layer metallization schemes. Common surface metallizing metals include silver, copper, titanium, and chromium. Existing literature (Acta Materialia, author: Evgeny Glickman, Volume 59, Issue 3, 2011, Pages 914-926) demonstrates that although gallium-based liquid metals and silver exhibit good thermal conductivity and wettability, prolonged contact leads to significant diffusion and penetration of gallium elements from silver into the liquid metal, resulting in the formation of brittle intermetallic compounds at the interface. It is foreseeable that brittle intermetallic compounds will be generated, leading to interface structure damage and increased thermal resistance. Similar to silver, other metals such as copper and aluminum will also be affected by the wetting reaction, which will directly lead to the destruction of the wetting layer metal (Reference: Materials Science and Engineering: A, Author: K. Ina, Volumes 387–389, 2004, Pages 390-394). This will result in significant hidden dangers to the thermal conductivity stability of composite materials under service conditions. Using easily carburized metals such as titanium (ACS Applied Materials & Interfaces 2020 12 (36), 40891-40900) and chromium (J Mater Sci: Mater Electron 34, 1395 (2023)) to metallize the surface of diamond will form corresponding carbides on its surface. To a certain extent, this can slightly improve the wetting performance of diamond and gallium-based liquid metal and reduce the interface thermal resistance. However, under high-temperature conditions, due to the erosion of gallium-based liquid metal, the stability of the composite material interface structure still needs to be improved (Journal of Materials Science: Materials in Electronics, Volume 30, pages 7194–7202, 2019).

[0006] Therefore, achieving spontaneous wetting of diamond by gallium-based liquid metal, avoiding the influence of low thermal conductivity oxide film on the surface of gallium-based liquid metal on the macroscopic thermal conductivity of composite materials, and developing long-lasting, high thermal conductivity diamond-gallium-based liquid metal composite thermal interface materials remain hot topics in current research on high thermal conductivity thermal interface materials, and are also an important direction for the interface design of gallium-based thermal interface materials for future thermal management. Summary of the Invention

[0007] To address the shortcomings of existing technologies, one objective of this invention is to provide a metallized diamond particle, which, when combined with gallium-based liquid metal, forms a composite material, enabling the diamond / gallium-based liquid metal composite material to exhibit superior thermal conductivity. A second objective is to provide a method for preparing metallized diamond particles that is easily applicable to industrial applications. A third objective is to provide a diamond / gallium-based liquid metal composite material with excellent thermal conductivity. A fourth objective is to provide a method for preparing the diamond / gallium-based liquid metal composite material.

[0008] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0009] A metallized diamond particle includes diamond particles, the surface of which is coated with a non-miscible alloy layer. The non-miscible alloy layer contains a diffusion-blocking component and a reactive wetting component. The content of the diffusion-blocking component in the non-miscible alloy layer is not higher than 15 at% of the total content of the diffusion-blocking component and the reactive wetting component. The diffusion-blocking component is one or more of tungsten, molybdenum, and tantalum, and the reactive wetting component is one or more of silver and copper.

[0010] Optionally, the thickness of the immiscible alloy layer is 30-300 nm, such as 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, or 290 nm.

[0011] Optionally, the diamond particles have a particle size of 10-500 μm, such as 50, 100, 200, 300, 350, 400, 450, or 450 μm, further 20-280 μm, even further 40-260 μm, still further 60-240 μm, even further 80-200 μm, and even further 100-180 μm.

[0012] Optionally, the content of diffusion-blocking components in the immiscible alloy layer is 2-12 at% of the total content of diffusion-blocking components and reactive wetting components, for example, specifically 3 at%, 4 at%, 5 at%, 6 at%, 7 at%, 8 at%, 9 at%, 10 at%, or 11 at%.

[0013] Optionally, the content of diffusion-blocking components in the immiscible alloy layer is 3-9 at the total content of diffusion-blocking components and reactive wetting components.

[0014] Based on the same inventive concept, this invention also provides: a method for preparing metallized diamond particles as described above, wherein a difficult-to-mix alloy layer is deposited on the surface of diamond particles by a non-equilibrium co-deposition method such as physical vapor deposition under an inert atmosphere to obtain metallized diamond particles; wherein, during physical vapor deposition, the diamond particles are controlled to be in a rolling or tumbling state to achieve uniform coating on each crystal plane of the diamond particles. Optionally, the powder material surface-modified carrier diamond particles described in CN200810143759.X can be used to conveniently achieve continuous stirring of the diamond particles during physical vapor deposition, thereby achieving more uniform coating.

[0015] Optionally, the diamond particles are cleaned and dried before physical vapor deposition; more specifically, the diamond particles are ultrasonically cleaned and dried with anhydrous ethanol before physical vapor deposition.

[0016] Alternatively, a difficult-to-mix alloy layer can be deposited on the surface of the diamond particles by magnetron sputtering.

[0017] Optionally, a dual-target magnetron sputtering focused co-deposition is performed using a first metal target and a second metal target; wherein the first metal target is one of a silver target and a copper target, and the second metal target is one of a tungsten target, a molybdenum target, and a tantalum target. When performing dual-target co-focused magnetron sputtering, the sputtering power of the first metal target is controlled to be 20-160W, further 40-140W, the sputtering power of the second metal target is 10-40W, further 20-30W, and the sputtering time is 10-100min, further 20-90min.

[0018] Alternatively, a single-target magnetron sputtering deposition can be performed using an alloy target; the alloy target consists of a diffusion barrier component and a reactive wetting component, wherein the content of the reactive wetting component in the alloy target is 70-99.9 wt%, or more specifically 85-95 wt%; during single-target magnetron sputtering deposition, the sputtering power of the alloy target is controlled at 80-220 W, or more specifically 100-200 W, and the sputtering time is 10-60 min, or more specifically 15-25 min.

[0019] Based on the same inventive concept, the present invention also provides: a diamond / gallium-based liquid metal composite material, comprising gallium-based liquid metal, wherein the gallium-based liquid metal contains metallized diamond particles as described above or metallized diamond particles prepared by the preparation method described above.

[0020] Optionally, in the diamond / gallium-based liquid metal composite material, the volume percentage of metallized diamond particles is not higher than 65 vol%, preferably 3-63 vol%; and / or, in the gallium-based liquid metal, the gallium content is 60-90 wt%, the indium content is 10-40 wt%, and the tin content is 0-20 wt%.

[0021] Optionally, in the gallium-based liquid metal, the gallium content is 65-85 wt%, more preferably 70-80 wt%, the indium content is 15-35 wt%, more preferably 20-30 wt%, and the tin content is 0-15 wt%, more preferably 5-10 wt%.

[0022] Optionally, the metallized diamond particles are randomly distributed within gallium-based liquid metal.

[0023] Optionally, in the immiscible alloy coating, some diffusion-blocking components are dissolved in the reactive wetting components, while other diffusion-blocking components are distributed in an amorphous state at the grain boundaries of the reactive wetting components.

[0024] Based on the same inventive concept, the present invention also provides: a method for preparing the diamond / gallium-based liquid metal composite material as described above, wherein metallized diamond particles and gallium-based liquid metal are mixed evenly under vacuum or protective atmosphere conditions, and then degassed to obtain the final product.

[0025] Therefore, by mechanically mixing and degassing metallized diamond particles and gallium-based liquid metal, a diamond / gallium-based liquid metal composite material can be obtained. By pre-setting a difficult-to-miscible alloy layer on the surface of the diamond particles, the thermal conductivity of the composite material can be improved, and the long-term effectiveness of its excellent thermal conductivity can be enhanced.

[0026] Optionally, the protective atmosphere is a nitrogen atmosphere.

[0027] Optionally, the metallized diamond particles and gallium-based liquid metal are mixed uniformly at room temperature.

[0028] Alternatively, the degassing method may be vacuum degassing.

[0029] The wetting of metallized diamond particles by gallium-based liquid metal can occur spontaneously in oxygen-free, oxygen-deficient, or oxygen-rich environments. Composite materials can be prepared under a protective atmosphere to avoid the influence of gallium-based liquid metal oxide on the thermal conductivity of the composite material. The resulting composite material has a stable interface structure and can withstand the erosion of gallium-based liquid metal for a long time, which helps to significantly improve the thermal conductivity and longevity of the composite material.

[0030] This invention employs a difficult-to-mix alloy layer to achieve surface metallization modification of diamond particles. By using reactive wetting components in the difficult-to-mix alloy layer that readily react with gallium-based liquid metal, spontaneous wetting of the metallized diamond particles by the gallium-based liquid metal is induced. Simultaneously, by using diffusion-blocking components in the difficult-to-mix alloy layer that exhibit excellent corrosion resistance to gallium-based liquid metal, the continuous reactive wetting is inhibited, thereby achieving the goal of improving the thermal conductivity and long-term interfacial stability of the composite material.

[0031] In the diamond / gallium-based liquid metal composite material of the present invention, by introducing a non-miscible alloy layer (metallization layer) on the surface of diamond particles, the wettability of gallium-based liquid metal to diamond particles under oxygen-free conditions is significantly improved by the reactive wetting component, achieving spontaneous wetting and avoiding the introduction of an oxide layer on the surface of gallium-based liquid metal, which reduces the thermal conductivity of the composite material. At the same time, by using a diffusion blocking component, the continuous wetting reaction between the reactive wetting component and gallium-based liquid metal (such as Ag-Ga, Ag-In) is suppressed, improving the corrosion resistance of the diamond surface metallization layer to gallium-based liquid metal, thereby greatly improving the long-term performance and service stability of the composite material.

[0032] This invention provides a diamond metallization modified film system design scheme, which can effectively and stably improve the thermal conductivity and performance stability of diamond / gallium-based liquid metal composite materials.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] Compared to the common single / double-layer metallization schemes used in the preparation of diamond / gallium-based liquid metal composite thermal interface materials, the immiscible alloy layer used in this invention has significant advantages in modifying diamond particles. Specifically, in the initial stage of contact between the immiscible alloy layer and the gallium-based liquid metal (such as gallium-indium alloy), the reactive wetting components are selectively dissolved in the gallium-based liquid metal, while the diffusion-blocking components solidified in the grains of the reactive wetting components precipitate at the interface. Together with the diffusion-blocking components that are already segregated in the grain boundary region of the reactive wetting components, they block the interdiffusion path between the reactive wetting components and the gallium-based liquid metal, thereby significantly inhibiting the continued progress of the interface wetting reaction. In this process, on the one hand, the spontaneous wetting of the immiscible alloy layer by the gallium-based liquid metal is promoted, avoiding the influence of the liquid metal oxide layer on the thermal conductivity of the composite material and helping to improve the thermal conductivity of the composite material; on the other hand, the interface stability of the composite material is greatly improved, so that the thermal conductivity of the diamond / gallium-based liquid metal composite material can be maintained at a high level for a long time, solving the problem of rapid decay of thermal conductivity and poor service stability of composite materials caused by traditional coating methods.

[0035] The preparation method of this invention employs mature and highly controllable processes, making it easy to achieve large-scale industrial production and possessing promising market application prospects. Attached Figure Description

[0036] Figure 1 This is a SEM image of the metallized diamond particles prepared in Example 1. Figure 1 a, Figure 1 b) and EDS diagram ( Figure 1 c. Figure 1 d).

[0037] Figure 2This is a SEM image of a cross-section of the metallized film (difficult-to-dissolve alloy layer) prepared in Example 1.

[0038] Figure 3 These are XRD images of the silver / tungsten thin films on the surface of the metallized diamond particles prepared in Examples 1 and 4.

[0039] Figure 4 These are TEM images of the silver / tungsten coating on the surface of the metallized diamond particles prepared in Example 1, wherein... Figure 4 a is the HAADF image of the silver / tungsten film. Figure 4 b is the elemental distribution diagram of the silver / tungsten thin film. Figure 4 c is the distribution map of Ag. Figure 4 d is the distribution diagram of W.

[0040] Figure 5 This is a SEM image of the surface of the diamond / gallium-based liquid metal composite material in Example 1.

[0041] Figure 6 The graph shows the change in thermal conductivity over time for the diamond / gallium-based liquid metal composite materials in Examples 1, 3, and 1 (Comparative Example 1). Detailed Implementation

[0042] The present invention will be described in detail below with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0043] Preferably, the diamond particles are subjected to ultrasonic cleaning. Specifically, acetone and alcohol are used sequentially as cleaning media for ultrasonic cleaning, with each cleaning session lasting 3-20 minutes. After cleaning, the particles are dried for later use to thoroughly remove surface oil and other impurities. Optionally, the diamond particles are placed in a magnetron sputtering powder stage and continuously agitated under an argon atmosphere for metallization modification using magnetron sputtering. The metallization modification of the diamond can be achieved using dual-target confocal or single-target magnetron sputtering methods. When using dual-target confocal magnetron sputtering, the composition and thickness of the immiscible alloy layer can be adjusted by changing the sputtering power and sputtering time of the reactive wetting target and the diffusion barrier target. Specifically, taking silver as a reactive wetting component and tungsten as a diffusion barrier component as an example, the proportion of silver in the immiscible alloy layer is controlled within the range of 1-0.8, and the corresponding proportion of tungsten is controlled within the range of 0-0.2 (with a co-sputtering time of 20-60 minutes). If diamond surface metallization is achieved by single-target magnetron sputtering, an alloy target containing a reactive wetting component is required. Taking a silver-tungsten alloy target as an example, the silver content in the target material is 70-99.9 wt%, with the remainder being tungsten. After magnetron sputtering metallization modification, the thickness of the immiscible alloy layer on the surface of the diamond particles is 10-300 nanometers. The metallized diamond particles were then transferred to a glove box, where they were mechanically mixed with gallium-based liquid metal under a nitrogen atmosphere. The resulting slurry was then degassed under vacuum to obtain a diamond / gallium-based liquid metal composite material. Finally, the chemical element content in the immiscible alloy layers of each embodiment and comparative example was measured using an energy-dispersive X-ray spectroscopy (EDS EDAXGENESIS 60S) instrument. The thermal conductivity of the composite materials in each embodiment and comparative example was measured using a laser scintillation method with a Netzsch LFA 467 (Germany).

[0044] Example 1

[0045] Diamond with a particle size of 60-80 mesh was selected, ultrasonically cleaned with acetone and ethanol, and then dried for later use. It was then metallized by dual-target confocal magnetron sputtering using a silver target (99.99wt% purity) and a tungsten target (99.95wt% purity), with the base vacuum level evacuated to 5×10⁻⁶. -4Argon gas was introduced into the atmosphere, and the sputtering pressure was set to 1 Pa. The sputtering power of the silver target was adjusted to 125 W, and the sputtering power of the tungsten target was adjusted to 30 W. Sputtering was performed for 20 minutes to obtain metallized diamond particles. At this time, the molar ratio of silver to tungsten on the surface of the metallized diamond particles was 95.0:5.0, and the thickness of the immiscible alloy layer (silver / tungsten thin film) was 75 nm. Then, the metallized diamond particles coated with silver / tungsten thin film were mechanically mixed with gallium indium liquid metal (75 wt% Ga, 25 wt% In) in a glove box under a nitrogen atmosphere. The volume ratio of gallium indium liquid metal to metallized diamond particles was 2:3. Finally, after vacuum degassing, a diamond / gallium-based liquid metal composite material was obtained.

[0046] Example 2

[0047] Diamond with a particle size of 60-80 mesh was selected, ultrasonically cleaned with acetone and ethanol, and then dried for later use. It was then metallized by dual-target confocal magnetron sputtering using a silver target (99.99wt% purity) and a tungsten target (99.95wt% purity), with the base vacuum level evacuated to 5×10⁻⁶. -4 Argon gas was introduced into the sputtering chamber at a pressure of 1 Pa. The sputtering power of the silver target was adjusted to 125 W, and the sputtering power of the tungsten target was adjusted to 30 W. Sputtering was performed for 90 minutes to obtain metallized diamond particles. At this point, the molar ratio of silver to tungsten in the immiscible alloy layer (silver / tungsten film) was 94.5:5.5, and the thickness of the immiscible alloy layer (silver / tungsten film) was 244 nm. Then, the metallized diamond particles coated with the silver / tungsten film were mechanically mixed with gallium indium tin liquid metal (68.5 wt% Ga, 21.5 wt% In, 10 wt% Sn) in a glove box under a nitrogen atmosphere. The volume ratio of gallium indium tin liquid metal to metallized diamond particles was 2:3. Finally, after vacuum degassing, a diamond / gallium-based liquid metal composite material was obtained.

[0048] Example 3

[0049] Diamond with a particle size of 60-80 mesh was selected, ultrasonically cleaned with acetone and ethanol, and then dried for later use. It was then metallized by dual-target confocal magnetron sputtering using a silver target (99.99wt% purity) and a tungsten target (99.95wt% purity), with the base vacuum level evacuated to 5×10⁻⁶. -4Argon gas was introduced into the atmosphere, and the sputtering pressure was set to 1 Pa. The sputtering power of the silver target was adjusted to 50 W, and the sputtering power of the tungsten target was adjusted to 30 W. Sputtering was carried out for 50 minutes to obtain metallized diamond particles. At this time, the molar ratio of silver to tungsten in the immiscible alloy layer (silver / tungsten film) was 90.5:9.5, and the thickness of the immiscible alloy layer was 79 nm. Then, the metallized diamond particles coated with silver / tungsten film were mechanically mixed with gallium indium liquid metal (75 wt% Ga, 25 wt% In) in a glove box under a nitrogen atmosphere. The volume ratio of gallium indium liquid metal to metallized diamond particles was 2:3. Finally, after vacuum degassing, diamond / gallium-based liquid metal composite material was obtained.

[0050] Example 4

[0051] Diamond with a particle size of 60-80 mesh was selected, ultrasonically cleaned with acetone and ethanol, and then dried for later use. It was then metallized by dual-target confocal magnetron sputtering using a silver target (99.99wt% purity) and a tungsten target (99.95wt% purity), with the base vacuum level evacuated to 5×10⁻⁶. -4 Argon gas was introduced into the atmosphere, and the sputtering pressure was set to 1 Pa. The sputtering power of the silver target was adjusted to 30 W, and the sputtering power of the tungsten target was also adjusted to 30 W. Sputtering was carried out for 60 minutes to obtain metallized diamond particles. At this time, the molar ratio of silver to tungsten in the immiscible alloy layer (silver / tungsten thin film) was 86.3:13.7, and the thickness of the immiscible alloy layer was 88 nm. Then, the metallized diamond particles coated with silver / tungsten thin film were mechanically mixed with gallium indium liquid metal (75 wt% Ga, 25 wt% In) in a glove box under a nitrogen atmosphere (it was found that spontaneous wetting was difficult to achieve). The volume ratio of gallium indium liquid metal to metallized diamond particles was 2:3. Finally, after vacuum degassing, diamond / gallium-based liquid metal composite material was obtained.

[0052] Example 5

[0053] Select diamond with a particle size of 60-80 mesh, ultrasonically clean it with acetone and ethanol, and then dry it for later use. Metallize it using a single-target magnetron sputtering with a silver / tungsten alloy target (90wt% silver content, balance tungsten), and evacuate the base vacuum to 5×10⁻⁶. -4 Argon gas was introduced into the mixture, and the sputtering pressure was set to 1 Pa, the sputtering power to 150 W, and the sputtering time to 20 minutes. Then, the metallized diamond particles coated with silver / tungsten film were mechanically mixed with gallium indium liquid metal (75% Ga, 25% In) in a glove box under nitrogen atmosphere. The volume ratio of gallium indium liquid metal to metallized diamond particles was 2:3. Finally, after vacuum degassing, diamond / gallium-based liquid metal composite material was obtained.

[0054] Example 6

[0055] Diamond with a particle size of 230-240 mesh was selected, ultrasonically cleaned with acetone and ethanol, and then dried for later use. It was then subjected to dual-target confocal magnetron sputtering metallization using a silver target (99.99wt% purity) and a tungsten target (99.95wt% purity), with the base vacuum level evacuated to 5×10⁻⁶. -4 Argon gas was introduced into the atmosphere, and the sputtering pressure was set to 1 Pa. The sputtering power of the silver target was adjusted to 125 W, and the sputtering power of the tungsten target was adjusted to 30 W. Sputtering was performed for 25 minutes to obtain metallized diamond particles. At this time, the molar ratio of silver to tungsten in the immiscible alloy layer (silver / tungsten film) was 95.1:4.9, and the thickness of the immiscible alloy layer was 81 nm. Then, the metallized diamond particles coated with silver / tungsten film were mechanically mixed with gallium indium liquid metal (75 wt% Ga, 25 wt% In) in a glove box under a nitrogen atmosphere. The volume ratio of gallium indium liquid metal to metallized diamond particles was 2:3. Finally, after vacuum degassing, diamond / gallium-based liquid metal composite material was obtained.

[0056] Example 7

[0057] Diamond with a particle size of 60-80 mesh was selected, ultrasonically cleaned with acetone and ethanol, and then dried for later use. It was then subjected to dual-target confocal magnetron sputtering metallization using a silver target (99.99wt% purity) and a molybdenum target (99.7wt% purity), with the base vacuum level evacuated to 5×10⁻⁶. -4 Argon gas was introduced into the atmosphere, and the sputtering pressure was set to 1 Pa. The sputtering power of the silver target was adjusted to 125 W, and the sputtering power of the molybdenum target was adjusted to 20 W. Sputtering was carried out for 20 minutes to obtain metallized diamond particles. At this time, the ratio of silver to molybdenum in the immiscible alloy layer (silver / molybdenum thin film) was 93.8:6.2, and the thickness of the immiscible alloy layer was 78 nm. Then, the metallized diamond particles coated with silver / molybdenum thin film were mechanically mixed with gallium indium liquid metal (75 wt% Ga, 25 wt% In) in a glove box under a nitrogen atmosphere. The volume ratio of gallium indium liquid metal to metallized diamond particles was 2:3. Finally, after vacuum degassing, diamond / gallium-based liquid metal composite material was obtained.

[0058] Example 8

[0059] Diamond with a particle size of 60-80 mesh was selected, ultrasonically cleaned with acetone and ethanol, and then dried for later use. It was then metallized by dual-target confocal magnetron sputtering using a silver target (99.99wt% purity) and a tungsten target (99.95wt% purity), with the base vacuum level evacuated to 5×10⁻⁶. -4Argon gas was introduced into the mixture, and the sputtering pressure was set to 1 Pa. The sputtering power of the silver target was adjusted to 150 W and the tungsten target to 30 W. Sputtering was carried out for 15 minutes to obtain metallized diamond particles. At this time, the molar ratio of silver to tungsten in the immiscible alloy layer was 97.5:2.5, and the thickness of the immiscible alloy layer was 80 nm. Then, the metallized diamond particles coated with silver / tungsten film were mechanically mixed with gallium indium liquid metal (75 wt% Ga, 25 wt% In) in a glove box under a nitrogen atmosphere. The volume ratio of gallium indium liquid metal to metallized diamond particles was 2:3. Finally, after vacuum degassing, diamond / gallium-based liquid metal composite material was obtained.

[0060] Example 9

[0061] Diamond with a particle size of 60-80 mesh was selected, ultrasonically cleaned with acetone and ethanol, and then dried for later use. It was then subjected to dual-target confocal magnetron sputtering metallization using a copper target (99.99wt% purity) and a tungsten target (99.95wt% purity), with the base vacuum level evacuated to 5×10⁻⁶. -4 Argon gas was introduced into the atmosphere, and the sputtering pressure was set to 1 Pa. The sputtering power of the copper target was adjusted to 140 W, and the sputtering power of the tungsten target was adjusted to 30 W. Sputtering was performed for 35 minutes to obtain metallized diamond particles. At this point, the molar ratio of copper to tungsten in the immiscible alloy layer was 94.1:5.9, and the film thickness was 78 nm. Then, the metallized diamond particles coated with copper / tungsten film were mechanically mixed with gallium-indium liquid metal (75 wt% Ga, 25 wt% In) in a glove box under a nitrogen atmosphere. The volume ratio of gallium-indium liquid metal to metallized diamond particles was 2:3. Finally, after vacuum degassing, a diamond / gallium-based liquid metal composite material was obtained.

[0062] Example 10

[0063] Diamond with a particle size of 60-80 mesh was selected, ultrasonically cleaned with acetone and ethanol, and then dried for later use. It was then metallized by dual-target confocal magnetron sputtering using a silver target (99.99wt% purity) and a tantalum target (99.7wt% purity), with the base vacuum level evacuated to 5×10⁻⁶. -4 Argon gas was introduced into the sputtering chamber at a pressure of 1 Pa. The sputtering power of the silver target was adjusted to 125 W and the sputtering power of the tantalum target to 20 W. Sputtering was performed for 30 minutes to obtain metallized diamond particles. At this point, the molar ratio of silver to tantalum in the immiscible alloy layer was 94.5:5.5, and the thickness of the immiscible alloy layer was 82 nm. Then, the metallized diamond particles coated with silver / tantalum thin films were mechanically mixed with gallium-indium liquid metal (75 wt% Ga, 25 wt% In) in a glove box under a nitrogen atmosphere. The volume ratio of gallium-indium liquid metal to metallized diamond particles was 2:3. Finally, after vacuum degassing, a diamond / gallium-based liquid metal composite material was obtained.

[0064] Comparative Example 1

[0065] Diamond with a particle size of 60-80 mesh was selected, ultrasonically cleaned with acetone and ethanol, and then dried for later use. It was then magnetron sputtered metallized using a pure silver target (99.99 wt%), with the base vacuum level evacuated to 5 × 10⁻⁶. -4 Argon gas was introduced into the mixture, and the sputtering pressure was set to 1 Pa. The sputtering power was adjusted to 150 W, and sputtering was performed for 15 minutes to obtain metallized diamond particles. Then, the metallized diamond particles coated with silver film were mechanically mixed with gallium indium liquid metal (75 wt% Ga, 25 wt% In) in a glove box under a nitrogen protective atmosphere. The volume ratio of gallium indium liquid metal to metallized diamond particles was 2:3. Finally, after vacuum degassing, diamond / gallium-based liquid metal composite material was obtained.

[0066] Comparative Example 2

[0067] Diamond with a particle size of 60-80 mesh was selected, ultrasonically cleaned with acetone and ethanol, and then dried for later use. It was then magnetron sputtered and metallized using a pure tungsten target (99.95 wt%), with the base vacuum level evacuated to 5 × 10⁻⁶. -4 Argon gas was introduced into the sputtering process, and the sputtering pressure was set to 1 Pa, the power was adjusted to 150 W, and the sputtering time was 30 minutes to obtain metallized diamond particles. Then, the diamond coated with a tungsten film was mechanically mixed with gallium indium liquid metal (75 wt% Ga, 25 wt% In) in air. The volume ratio of gallium indium liquid metal to metallized diamond particles was 2:3. Finally, after vacuum degassing, diamond / gallium-based liquid metal composite material was obtained.

[0068] Comparative Example 3

[0069] Diamond with a particle size of 60-80 mesh was selected, ultrasonically cleaned with acetone and ethanol, and then dried for later use. It was then magnetron sputtered and metallized using a pure molybdenum target (99.7 wt%), with the base vacuum level evacuated to 5 × 10⁻⁶. -4 Argon gas was introduced into the sputtering chamber, and the sputtering pressure was set to 1 Pa. The sputtering power was adjusted to 150 W, and sputtering was carried out for 30 minutes to obtain metallized diamond particles. Then, the metallized diamond particles coated with a molybdenum film were mechanically mixed with gallium indium liquid metal (75 wt% Ga, 25 wt% In) in air. The volume ratio of gallium indium liquid metal to metallized diamond particles was 2:3. Finally, after vacuum degassing, diamond / gallium-based liquid metal composite material was obtained.

[0070] Comparative Example 4

[0071] Diamond particles with a particle size of 60-80 mesh are selected, ultrasonically cleaned with acetone and ethanol, and then dried for later use. Next, the diamond particles are mechanically mixed with gallium indium liquid metal (75wt%Ga, 25wt%In) in air, with a volume ratio of gallium indium liquid metal to metallized diamond particles of 2:3. Finally, after vacuum degassing, diamond / gallium-based liquid metal composite material is obtained.

[0072] See Figure 1 In Example 1, the metallized diamond particles largely maintained the original regular shape of the diamond particles, with Ag and W evenly distributed on the surface of the diamond particles. See also... Figure 2 The silver / tungsten coating (a non-miscible alloy layer) on the surface of the diamond particles has a uniform thickness and a tight interface with the diamond particles, with no micro-cracks observed. Therefore, this invention achieves uniform and high-quality silver / tungsten film coating.

[0073] See Figure 3 All silver / tungsten coatings in each group showed obvious Ag characteristic peaks.

[0074] See Figure 4 In immiscible alloy coatings, some diffusion-blocking components (W) are dissolved in the reactive wetting components (Ag), while the remaining diffusion-blocking components are distributed in an amorphous state at the grain boundaries of the reactive wetting components. Therefore, Figure 3 No characteristic peak of W was observed in the middle.

[0075] See Figure 5 The metallized diamond particles are randomly dispersed in gallium-indium liquid metal without agglomeration, and the metallized diamond particles are well wetted with the gallium-based liquid metal.

[0076] See Figure 6 The thermal conductivity of the diamond / gallium-based liquid metal composite material of the present invention does not change significantly over time and can remain at a high level for a long time. The test temperature condition was room temperature storage.

[0077] The thermal conductivity test results (measured within 12 hours after vacuum degassing) of the diamond / gallium-based liquid metal composite materials prepared in each embodiment and comparative example are shown in Table 1. Specifically, the composite material prepared in Example 1 has a thermal conductivity as high as 175 W·m. -1 ·K -1Gallium-indium liquid metal can spontaneously wet the surface of metallized diamond particles and exhibits excellent wetting stability. Compared to Comparative Example 1, the thermal conductivity of the composite material in Example 1 increased by 52%, possibly because the doping of tungsten effectively improved the interfacial wetting stability between diamond and gallium-based liquid metal. Compared to Comparative Example 2, the thermal conductivity of the composite material in Example 1 also increased by 23%, possibly because the presence of silver overcame the defect that gallium-indium liquid metal cannot spontaneously wet the diamond surface. In Example 2, the thickness of the immiscible alloy layer was increased, and the thermal conductivity of the composite material decreased, but it was still significantly better than the composite material obtained by introducing a pure metallization layer in the Comparative Example. In Examples 3, 4, and 8, the ratio of silver to tungsten in the immiscible alloy layer was changed. It can be seen that the composition of the immiscible alloy layer on the diamond surface has a significant impact on the thermal conductivity of the composite material. When the tungsten content increased to 9.5%, the thermal conductivity decreased to 142 W·m. -1 ·K -1 When the tungsten content reaches 13.7%, the thermal conductivity decreases to 134 W·m. -1 ·K -1 At this point, the gallium-indium liquid metal cannot spontaneously wet the surface of the metallized diamond particles; when the tungsten content is further reduced to 2.5%, the thermal conductivity decreases to 120 W·m. -1 ·K -1 The possible reason is that, at this point, the initial wettability between the gallium-indium liquid metal and the coated diamond is good, but due to the low tungsten content, the diffusion barrier layer cannot fully function, resulting in poor interfacial wetting stability. Example 5 uses a silver-tungsten alloy single target to metallize and modify diamond. When the composition of the metallization layer is similar to that in Example 1, the thermal conductivity of the composite material reaches 180 W·m. -1 ·K -1 In Example 6, by adjusting the diamond particle size to 230-240 mesh, the surface metallization modification of the diamond particles can still be achieved using magnetron sputtering. Although the thermal conductivity of the prepared composite material is affected to some extent by the diamond particle size, it can still reach 154 W·m. -1 ·K -1 Examples 7 and 10 involve adjustments to the diffusion barrier components. In Example 7, molybdenum was selected as the diffusion barrier component. When the molybdenum content in the metallization layer was 6.2%, the thermal conductivity of the composite material reached 162 W·m. -1 ·K -1 Compared to Comparative Example 3, the thermal conductivity is improved by up to 32%, while achieving spontaneous wetting of gallium-indium liquid metal on silver / molybdenum diamond surfaces. In Example 10, tantalum was chosen instead of tungsten, and the thermal conductivity of the composite material reached 163 W·m. -1 ·K -1Furthermore, spontaneous wetting of the diamond surface coated with gallium-indium liquid metal was achieved. The above two examples demonstrate that molybdenum and tantalum, as diffusion barrier components, can also play a role similar to tungsten. In Example 9, copper was used instead of silver as the reactive wetting component. When the copper content was 94.1%, the thermal conductivity of the composite material reached 166 W·m. -1 ·K -1 Self-wetting can occur between the gallium-indium liquid metal and the coated diamond, but the wettability is not as good as in Example 1. Through cross-validation between the above examples and comparative examples, the function and universality of the bifunctional immiscible alloy layer on the diamond surface of the present invention are further illustrated.

[0078]

[0079] In summary, this invention, through the innovative design of a difficult-to-miscible alloy layer on the diamond surface, successfully improves the interfacial wettability between liquid metal and diamond, greatly reduces interfacial thermal resistance, and increases interfacial thermal conductivity. By doping a small amount of diffusion-blocking components into the reactive wetting component silver, high thermal conductivity is ensured while significantly improving interfacial stability and the service performance of the composite material.

[0080] The above embodiments should be understood as being used only to illustrate the present invention more clearly, and not to limit the scope of the present invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope defined by the appended claims.

Claims

1. A metallized diamond particle, comprising diamond particles, characterized in that, The surface of the diamond particles is coated with a non-miscible alloy layer, which contains diffusion-blocking components and reactive wetting components. The content of diffusion-blocking components in the non-miscible alloy layer is not higher than 15 at% of the total content of diffusion-blocking components and reactive wetting components. The diffusion-blocking components are one or more of tungsten, molybdenum, and tantalum, and the reactive wetting components are one or more of silver and copper.

2. The metallized diamond particles according to claim 1, characterized in that, The thickness of the immiscible alloy layer is 30-300 nm.

3. The metallized diamond particles according to claim 1, characterized in that, The diamond particles have a particle size of 10-500 μm.

4. The metallized diamond particles according to any one of claims 1-3, characterized in that, The content of diffusion-blocking components in the immiscible alloy layer is 2-12 at the total content of diffusion-blocking components and reactive wetting components.

5. The metallized diamond particles according to claim 4, characterized in that, The content of diffusion-blocking components in the immiscible alloy layer is 3-9 at the total content of diffusion-blocking components and reactive wetting components.

6. The method for preparing metallized diamond particles according to any one of claims 1-5, characterized in that, Metallized diamond particles are obtained by depositing a difficult-to-miscible alloy layer on the surface of diamond particles through physical vapor deposition in an inert atmosphere; wherein, during physical vapor deposition, the diamond particles are controlled to be in a rolling or tumbling state.

7. The preparation method according to claim 6, characterized in that, A difficult-to-mix alloy layer is deposited on the surface of diamond particles by magnetron sputtering. Dual-target magnetron sputtering co-deposition was performed using a first metal target and a second metal target. The first metal target was either a silver target or a copper target, and the second metal target was either a tungsten target, a molybdenum target, or a tantalum target. During dual-target magnetron sputtering co-deposition, the sputtering power of the first metal target was controlled at 20-160W, the sputtering power of the second metal target was controlled at 10-40W, and the sputtering time was controlled at 10-100min. Alternatively, a single-target magnetron sputtering deposition can be performed using an alloy target; wherein the alloy target is composed of a diffusion barrier component and a reactive wetting component, and the content of the reactive wetting component in the alloy target is 70-99.9 wt%; when performing single-target magnetron sputtering deposition, the sputtering power of the alloy target is controlled at 80-220 W and the sputtering time is 10-60 min.

8. A diamond / gallium-based liquid metal composite material, comprising gallium-based liquid metal, characterized in that, The gallium-based liquid metal contains metallized diamond particles as described in any one of claims 1-5 or metallized diamond particles prepared by the preparation method described in any one of claims 6-7.

9. The diamond / gallium-based liquid metal composite material according to claim 8, characterized in that, In the diamond / gallium-based liquid metal composite material, the volume percentage of metallized diamond particles is not higher than 65 vol%, preferably 3-63 vol%; and / or, in the gallium-based liquid metal, the gallium content is 60-90 wt%, the indium content is 10-40 wt%, and the tin content is 0-20 wt%.

10. The method for preparing the diamond / gallium-based liquid metal composite material as described in claim 8 or 9, characterized in that, Under vacuum or protective atmosphere conditions, metallized diamond particles and gallium-based liquid metal are mixed evenly and then degassed to obtain the final product.

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