Liquid metal for liquid cooling line coolant

Abstract

The present invention discloses a liquid metal for liquid cooling line coolant, belonging to the field of liquid metal material technology. The method comprises the following steps: mixing a liquid metal mixture with deionized water containing polyvinyl pyrrolidone, centrifuging, and filtering to obtain liquid metal droplets; mixing the liquid metal droplets with a LDH precursor solution, applying a periodic electric field for electrolysis, and obtaining LDH-coated liquid metal; heating and insulating the LDH-coated liquid metal, adjusting the pH to 8.0 with 0.1M hydrochloric acid, adding a functionalizing agent, stirring, centrifuging, washing 2 to 3 times with deionized water or anhydrous ethanol, and vacuum drying to obtain the liquid metal for liquid cooling line coolant. The present invention prepares a liquid metal for liquid cooling line coolant with high thermal conductivity, reduces the corrosion performance of the liquid metal, improves thermal cycle stability and heat transfer efficiency, and has excellent long-term stability, significantly improving the application range and engineering application value of the liquid metal coolant.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid metal materials, in particular to liquid metal for liquid cooling line coolant. Background Art

[0002] Liquid metal coolants are an advanced class of heat transfer media based on low-melting-point metals or alloys. Their unique physicochemical properties hold great promise for thermal management in electronic devices. Liquid metal's superior heat transfer performance stems from the sea of ​​free electrons within its metallic bond structure. These high-mobility electrons not only provide excellent electrical conductivity but, more importantly, impart extremely high thermal conductivity, according to the Wiedemann-Franz law (κ=LσT). For example, the typical gallium-indium-tin ternary eutectic alloy (Galinstan) exhibits a room-temperature thermal conductivity of 16.5–26.4 W / m·K, more than an order of magnitude higher than that of conventional organic coolants. Liquid metals also possess advantages such as near-zero vapor pressure, a wide liquidus temperature range, and a high heat capacity (130–160 J / kg·K), theoretically enabling efficient and stable phase-change cooling. From a microscopic perspective, the heat transfer mechanisms in liquid metals involve the synergistic effects of electronic conduction, phonon conduction, and convective mass transfer, with electronic conduction being dominant. This enables rapid heat transfer at relatively low temperature gradients. In addition, some liquid metal alloy systems also exhibit temperature-controlled phase change characteristics, that is, solid-liquid phase change occurs within a specific temperature range, and more efficient temperature regulation can be achieved through latent heat absorption. This phase change cooling mechanism has significant advantages when processing high heat flux density electronic devices.

[0003] However, existing liquid metal cooling technology still faces many severe technical challenges, which seriously limit its engineering application. First, the problem of fluid dynamics control is prominently manifested in the high fluidity and low viscosity (about 2mPa·s) of traditional gallium-based alloys at room temperature. Although this characteristic is conducive to convective heat transfer, it leads to serious flow control difficulties and leakage risks in practical applications, especially in microchannels or complex geometric structures, where liquid metal is prone to unexpected flow and aggregation. Secondly, the interfacial compatibility problem stems from the complex physical and chemical interactions between liquid metal and solid materials, including poor wettability (contact angle is usually greater than 120°), interfacial corrosion, and the formation of intermetallic compounds. These problems will lead to increased interfacial thermal resistance and decreased structural integrity. For example, when gallium-based liquid metal comes into contact with aluminum alloy, brittle intermetallic compounds such as Al2Ga3 and Al5Ga2 will be formed, triggering liquid metal embrittlement (LME) phenomenon, which seriously threatens system reliability. The inherent contradiction between thermal conductivity efficiency and material stability is also very prominent: high thermal conductivity requires high electron density and strong metallic properties, but this also means high chemical activity and a tendency for interfacial reactions. While adding stabilizing elements or forming a protective oxide film can improve stability, it significantly reduces thermal conductivity. In terms of preparation technology, traditional melting and mixing methods have difficulty in precisely controlling the microstructure and compositional uniformity of multi-element alloys, and are prone to defects such as composition segregation and phase separation. At the same time, the high-temperature oxidation loss of active metal elements also increases the complexity of composition control.

[0004] Although reference CN119571177B achieves certain temperature-controlled phase transition characteristics through the collaborative design of multiple elements such as Cd, Pb, Bi, In, Al, Zn, Sn, and Nb, this technical route still has significant limitations. The phase diagram of the eight-element composite system is extremely complex, involving dozens of possible binary and ternary intermetallic compound phases, making composition optimization and phase structure prediction extremely difficult, and it is difficult to achieve precise performance control. Although the introduction of heavy metal elements Cd and Pb can lower the melting point of the alloy, it seriously violates the concept of modern green manufacturing and does not comply with international environmental protection standards such as RoHS, limiting its application prospects in consumer electronics and other fields. Traditional melting and mixing processes present significant technical bottlenecks when processing multi-element systems: significant density differences between elements (e.g., Pb density of 11.34 g / cm³ and Al density of 2.70 g / cm³) lead to severe gravitational segregation; significant differences in melting points (Al melting point of 660°C and Sn melting point of 232°C) make homogenization difficult; and oxidation losses of active elements during high-temperature melting are difficult to control, resulting in poor batch-to-batch composition reproducibility. Furthermore, this technology fails to fundamentally address core technical challenges of liquid metal production, such as improving interfacial wettability, ensuring long-term cyclic stability, and controlling costs. It remains at the laboratory proof-of-concept stage, far from commercialization. Summary of the Invention

[0005] In order to address the shortcomings of the existing technology, the present invention limits the composition and content of the liquid metal components, combines LDH precursor solution for surface modification and functionalization reagent for surface treatment, and prepares a liquid metal for liquid cooling line coolant with high thermal conductivity, achieving a comprehensive improvement in thermal conductivity, electrical conductivity and corrosion resistance, and having excellent long-term stability.

[0006] The present invention provides a liquid metal for liquid cooling line coolant, which is prepared by the following steps:

[0007] Step 1: mixing the liquid metal mixture with deionized water containing polyvinyl pyrrolidone, centrifuging, and filtering to obtain liquid metal droplets;

[0008] It can be understood that the present application adds polyvinyl pyrrolidone as a non-ionic surfactant to prevent the occurrence of liquid metal aggregation through the steric hindrance effect.

[0009] Step 2: Dissolve magnesium nitrate hexahydrate and aluminum nitrate nonahydrate in deionized water at 20-30°C under nitrogen protection, stir to dissolve, adjust the pH to 9.2-9.7 with 0.5M sodium hydroxide solution, and then incubate in a water bath at 60°C under nitrogen protection for 10-12 hours to obtain an LDH precursor solution;

[0010] It is understandable that under alkaline conditions, Mg 2+ and Al 3+ Formation of layered double hydroxide [Mg 1-x Al x (OH)2] x+ structure; based on the solubility product constant, this application controls and adjusts the pH to 9.2~9.7 to ensure complete coprecipitation and avoid the formation of single-phase hydroxide; by controlling the temperature at 60°C for hydrothermal treatment, the crystal perfection is promoted to form a regular layered structure.

[0011] Step 3: mixing the liquid metal droplets with the LDH precursor solution, applying a periodic electric field for electrolysis, and obtaining the LDH-coated liquid metal;

[0012] It can be understood that the present application constructs a continuous conductive path through the LDH coating layer, eliminates the contact barrier, reduces the interface resistance, and thus improves the electrical conductivity of the liquid metal; the LDH layered structure channel optimizes the phonon transmission path, reduces interface scattering, and thus improves the thermal conductivity of the liquid metal.

[0013] Step 4: Heat and keep the LDH-coated liquid metal warm, adjust the pH to 8.0 with 0.1M hydrochloric acid, add a functionalizing reagent, stir, centrifuge, wash 2 to 3 times with deionized water or anhydrous ethanol, and vacuum dry to obtain liquid metal for liquid cooling line coolant.

[0014] Preferably, the liquid metal mixture is prepared by the following steps: adding gallium, indium and tin into a vacuum induction furnace, keeping the temperature under argon protection, and then cooling to 15-30° C. to obtain the liquid metal mixture.

[0015] Preferably, the weight ratio of gallium, indium and tin is 60-70:20-22:10-12, the holding temperature is 750-780° C., the holding time is 2-3 h, and the cooling rate is 5-8° C. / min.

[0016] It can be understood that the present application forms a low-melting-point eutectic alloy by controlling the ratio of the Ga-In-Sn system, which remains liquid at room temperature and conforms to the Euler-Gabot law; controls the holding temperature to be much higher than the melting point of each component to ensure complete melting and uniform mixing at the atomic level; controls the cooling rate to avoid excessive solidification to produce component segregation, and obtains a uniform microstructure.

[0017] Preferably, the mass fraction of polyvinyl pyrrolidone in the deionized water containing polyvinyl pyrrolidone is 0.5 wt %.

[0018] Preferably, in the step 1, the centrifugal speed is 8000-12000 rpm, the centrifugal time is 15-20 min, and the filtration is performed using a nylon filter or a stainless steel filter with a pore size of 50-200 μm.

[0019] It can be understood that the present application generates strong shear force through high-speed centrifugation to break up large chunks of liquid metal into micron-sized droplets; controls the pore size of the filter to ensure the uniformity of the particle size, and provides an ideal substrate for subsequent coating.

[0020] Preferably, in step 2, the weight ratio of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and deionized water is 7.5-8.0:3.7-3.8:500, the stirring rate of the stirring dissolution is 200-300 rpm, and the stirring time is 15-30 min.

[0021] Preferably, in step three, the weight ratio of the liquid metal droplets to the LDH precursor solution is 1:3-5.

[0022] Preferably, the periodic electric field parameters are: using a titanium mesh anode and a stainless steel 316L cathode, an electrode spacing of 20 mm, applying a 2.5 V DC voltage, a current density of 0.5-1.0 A / dm², an electric field cycle of 10 min, in each cycle the forward electric field duration is 6 min, the reverse electric field duration is 4 min, and the electrolysis time is 45-60 min.

[0023] It can be understood that the present application utilizes a positive electric field to promote the migration of the positively charged LDH precursor to the cathode (liquid metal surface), and utilizes a reverse electric field to eliminate concentration polarization, thereby ensuring that the coating layer is uniform and dense.

[0024] Preferably, the functionalizing agent is prepared by dissolving octadecylamine in ethanol to prepare a 0.8 mol / L solution, ultrasonically dispersing the solution at a power of 300 W and a frequency of 40 kHz for 30 minutes, and adjusting the pH to 7.5-8.5.

[0025] It can be understood that the octadecylamine added in the present application forms an ordered molecular film on the surface of LDH through van der Waals force, with the long alkyl chains facing outward to form a hydrophobic protective layer to block the corrosive medium. The formation of the organic film increases the surface resistance of the liquid metal and reduces the driving force of electrochemical corrosion.

[0026] Preferably, in the step 4, the weight ratio of the LDH-coated liquid metal to the functionalizing reagent is 1:0.08~0.12, the heating and insulation heating rate is 2°C / min, the insulation temperature is 60~70°C, the pH adjustment rate is 0.1 pH unit / min, the stirring temperature is 40~50°C, the stirring time is 2~3h, the stirring rate is 200rpm, the centrifugal rate is 2500~3000rpm, the centrifugal time is 15~20min, and the vacuum drying is vacuum drying at 55~60°C for 10~12h.

[0027] The present invention has the following beneficial effects:

[0028] (1) The present invention optimizes the phonon transmission path through the LDH layered structure, combines periodic electric field treatment to reduce the interface thermal resistance, and improves the thermal conductivity of the liquid metal; constructs a continuous conductive path through the LDH coating layer, reduces the contact resistance, and significantly improves the electrical conductivity of the liquid metal; through the synergistic effect of the LDH barrier layer and the functionalized protective film, the corrosiveness of the liquid metal is reduced, and the scope of industrial application is expanded; through the multi-level structure, thermal stress is effectively relieved, and the thermal cycling stability of the liquid metal is improved.

[0029] (2) The technical solution of the present invention selects periodic electric field treatment to achieve precise control, has high preparation reproducibility and is suitable for large-scale industrial application. DETAILED DESCRIPTION

[0030] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] Example 1

[0032] Step 1: Prepare a liquid metal mixture: add 65 g of gallium, 21 g of indium, and 11 g of tin into a vacuum induction furnace, keep it at 765°C for 2.5 hours under argon protection, and then cool it to 22°C at a cooling rate of 6.5°C / min to obtain a liquid metal mixture.

[0033] Step 2: preparing liquid metal droplets: 100 g of the liquid metal mixture was mixed with 2000 g of deionized water containing 0.5 wt% polyvinyl pyrrolidone, centrifuged at 10,000 rpm for 17.5 min, and filtered through a nylon filter with a pore size of 125 μm to obtain liquid metal droplets.

[0034] Step 3. Prepare LDH precursor solution: Under nitrogen protection at 25°C, dissolve 7.75g of magnesium nitrate hexahydrate and 3.75g of aluminum nitrate nonahydrate in 500g of deionized water, stir and dissolve at 250rpm for 22.5min, adjust the pH to 9.45 with 0.5M sodium hydroxide solution, and then incubate in a water bath at 60°C under nitrogen protection for 11h to obtain an LDH precursor solution.

[0035] Step 4: Electrolytic coating: The liquid metal droplets were mixed with the LDH precursor solution in a weight ratio of 1:4. A titanium mesh anode and a stainless steel 316L cathode were used. The electrode spacing was 20 mm. A DC voltage of 2.5 V was applied, the current density was 0.75 A / dm², the electric field cycle was 10 min, the forward electric field duration in each cycle was 6 min, the reverse electric field duration was 4 min, and the electrolysis time was 52.5 min to obtain LDH-coated liquid metal.

[0036] Step 5: Functionalization treatment: octadecylamine was dissolved in ethanol to prepare a 0.8 mol / L solution, ultrasonically dispersed at a power of 300 W and a frequency of 40 kHz for 30 minutes, and the pH was adjusted to 8.0 to prepare a functionalization reagent. The LDH-coated liquid metal was heated to 65°C at a heating rate of 2°C / min and kept warm. The pH was adjusted to 8.0 with 0.1M hydrochloric acid at a rate of 0.1 pH unit / min. The functionalization reagent was added (the weight ratio of the LDH-coated liquid metal functionalization reagent was 1:0.10), stirred at 200 rpm for 2.5 hours at 45°C, centrifuged at 2750 rpm for 17.5 minutes, washed twice with deionized water and anhydrous ethanol, and vacuum dried at 57.5°C for 11 hours to obtain the liquid metal for the liquid cooling line coolant.

[0037] Example 2

[0038] Step 1: Prepare a liquid metal mixture: add 60 g of gallium, 20 g of indium, and 10 g of tin into a vacuum induction furnace, keep it at 750°C for 2 hours under argon protection, and then cool it to 15°C at a cooling rate of 5°C / min to obtain a liquid metal mixture.

[0039] Step 2: preparing liquid metal droplets: 100 g of the liquid metal mixture was mixed with 2000 g of deionized water containing 0.5 wt% polyvinyl pyrrolidone, centrifuged at 8000 rpm for 15 min, and filtered through a stainless steel filter with a pore size of 50 μm to obtain liquid metal droplets.

[0040] Step 3. Prepare LDH precursor solution: Under nitrogen protection at 20°C, dissolve 7.5g of magnesium nitrate hexahydrate and 3.7g of aluminum nitrate nonahydrate in 500g of deionized water, stir and dissolve at 200rpm for 15min, adjust the pH to 9.2 with 0.5M sodium hydroxide solution, and then incubate in a water bath at 60°C under nitrogen protection for 10h to obtain an LDH precursor solution.

[0041] Step 4: Electrolytic coating: Mix the liquid metal droplets with the LDH precursor solution in a weight ratio of 1:3, use a titanium mesh anode and a stainless steel 316L cathode, with an electrode spacing of 20 mm, apply a 2.5 V DC voltage, a current density of 0.5 A / dm², and an electric field cycle of 10 minutes. In each cycle, the forward electric field lasts for 6 minutes, the reverse electric field lasts for 4 minutes, and the electrolysis time is 45 minutes to obtain LDH-coated liquid metal.

[0042] Step 5: Functionalization treatment: octadecylamine was dissolved in ethanol to prepare a 0.8 mol / L solution, ultrasonically dispersed at a power of 300 W and a frequency of 40 kHz for 30 minutes, and the pH was adjusted to 7.5 to prepare a functionalization reagent. The LDH-coated liquid metal was heated to 60°C at a heating rate of 2°C / min and kept warm. The pH was adjusted to 8.0 with 0.1M hydrochloric acid at a rate of 0.1 pH unit / min. The functionalization reagent was added (the weight ratio of the LDH-coated liquid metal functionalization reagent was 1:0.08), stirred at 200 rpm for 2 hours at 40°C, centrifuged at 2500 rpm for 15 minutes, washed with deionized water and anhydrous ethanol three times each, and vacuum dried at 55°C for 10 hours to obtain the liquid metal for liquid cooling line coolant.

[0043] Example 3

[0044] Step 1: Prepare a liquid metal mixture: add 70 g of gallium, 22 g of indium, and 12 g of tin into a vacuum induction furnace, keep it at 780°C for 3 hours under argon protection, and then cool it to 30°C at a cooling rate of 8°C / min to obtain a liquid metal mixture.

[0045] Step 2: preparing liquid metal droplets: 100 g of the liquid metal mixture was mixed with 2000 g of deionized water containing 0.5 wt% polyvinyl pyrrolidone, centrifuged at 12000 rpm for 20 min, and filtered through a nylon filter with a pore size of 200 μm to obtain liquid metal droplets.

[0046] Step 3. Prepare LDH precursor solution: Under nitrogen protection at 30°C, dissolve 8.0g of magnesium nitrate hexahydrate and 3.8g of aluminum nitrate nonahydrate in 500g of deionized water, stir and dissolve at 300rpm for 30min, adjust the pH to 9.7 with 0.5M sodium hydroxide solution, and then incubate in a water bath at 60°C under nitrogen protection for 12h to obtain an LDH precursor solution.

[0047] Step 4: Electrolytic coating: Mix the liquid metal droplets with the LDH precursor solution in a weight ratio of 1:5, use a titanium mesh anode and a stainless steel 316L cathode, with an electrode spacing of 20 mm, apply a 2.5 V DC voltage, a current density of 1.0 A / dm², and an electric field cycle of 10 min. In each cycle, the forward electric field lasts for 6 min, the reverse electric field lasts for 4 min, and the electrolysis time is 60 min to obtain LDH-coated liquid metal.

[0048] Step 5: Functionalization treatment: octadecylamine was dissolved in ethanol to prepare a 0.8 mol / L solution, ultrasonically dispersed at a power of 300 W and a frequency of 40 kHz for 30 minutes, and the pH was adjusted to 8.5 to prepare a functionalization reagent. The LDH-coated liquid metal was heated to 70°C at a heating rate of 2°C / min and kept warm. The pH was adjusted to 8.0 with 0.1M hydrochloric acid at a rate of 0.1 pH unit / min. The functionalization reagent was added (the weight ratio of the LDH-coated liquid metal functionalization reagent was 1:0.12), stirred at 200 rpm for 3 hours at 50°C, centrifuged at 3000 rpm for 20 minutes, washed twice with deionized water and anhydrous ethanol, and vacuum dried at 60°C for 12 hours to obtain the liquid metal for the liquid cooling line coolant.

[0049] Example 4

[0050] Step 1: Prepare a liquid metal mixture: add 62 g of gallium, 21 g of indium, and 11 g of tin in a weight ratio of 62:21:11 into a vacuum induction furnace, keep it at 760°C for 2.2 hours under argon protection, and then cool it to 20°C at a cooling rate of 6°C / min to obtain a liquid metal mixture.

[0051] Step 2: preparing liquid metal droplets: 100 g of the liquid metal mixture was mixed with 2000 g of deionized water containing 0.5 wt% polyvinyl pyrrolidone, centrifuged at 9000 rpm for 18 min, and filtered through a stainless steel filter with a pore size of 100 μm to obtain liquid metal droplets.

[0052] Step 3. Prepare LDH precursor solution: Under nitrogen protection at 22°C, dissolve 7.6g of magnesium nitrate hexahydrate and 3.72g of aluminum nitrate nonahydrate in 500g of deionized water, stir and dissolve at 220rpm for 20min, adjust the pH to 9.3 with 0.5M sodium hydroxide solution, and then incubate in a water bath at 60°C under nitrogen protection for 10.5h to obtain an LDH precursor solution.

[0053] Step 4: Electrolytic coating: Mix the liquid metal droplets with the LDH precursor solution in a weight ratio of 1:3.5, use a titanium mesh anode and a stainless steel 316L cathode, with an electrode spacing of 20 mm, apply a 2.5 V DC voltage, a current density of 0.6 A / dm², and an electric field cycle of 10 min. In each cycle, the forward electric field lasts for 6 min, the reverse electric field lasts for 4 min, and the electrolysis time is 48 min to obtain LDH-coated liquid metal.

[0054] Step 5: Functionalization treatment: octadecylamine was dissolved in ethanol to prepare a 0.8 mol / L solution, ultrasonically dispersed at a power of 300 W and a frequency of 40 kHz for 30 minutes, and the pH was adjusted to 7.8 to prepare a functionalization reagent. The LDH-coated liquid metal was heated to 62°C at a heating rate of 2°C / min and kept warm. The pH was adjusted to 8.0 with 0.1M hydrochloric acid at a rate of 0.1 pH unit / min. The functionalization reagent was added (the weight ratio of the LDH-coated liquid metal functionalization reagent was 1:0.09), stirred at 200 rpm for 2.2 hours at 42°C, centrifuged at 2600 rpm for 16 minutes, washed twice with deionized water and anhydrous ethanol, and vacuum dried at 56°C for 10.5 hours to obtain the liquid metal for the liquid cooling line coolant.

[0055] Example 5

[0056] Step 1: Prepare a liquid metal mixture: add 68 g of gallium, 21.5 g of indium, and 11.5 g of tin in a weight ratio of 68:21.5:11.5 into a vacuum induction furnace, keep warm at 775°C for 2.8 hours under argon protection, and then cool to 28°C at a cooling rate of 7.5°C / min to obtain a liquid metal mixture.

[0057] Step 2: preparing liquid metal droplets: 100 g of the liquid metal mixture was mixed with 2000 g of deionized water containing 0.5 wt% polyvinyl pyrrolidone, centrifuged at 11000 rpm for 19 min, and filtered through a nylon filter with a pore size of 150 μm to obtain liquid metal droplets.

[0058] Step 3. Prepare LDH precursor solution: Under nitrogen protection at 28°C, dissolve 7.9g of magnesium nitrate hexahydrate and 3.79g of aluminum nitrate nonahydrate in 500g of deionized water, stir and dissolve at 280rpm for 28min, adjust the pH to 9.6 with 0.5M sodium hydroxide solution, and then incubate in a water bath at 60°C under nitrogen protection for 11.5h to obtain an LDH precursor solution.

[0059] Step 4: Electrolytic coating: The liquid metal droplets were mixed with the LDH precursor solution in a weight ratio of 1:4.5. A titanium mesh anode and a stainless steel 316L cathode were used with an electrode spacing of 20 mm. A DC voltage of 2.5 V was applied, the current density was 0.9 A / dm², the electric field cycle was 10 min, the forward electric field duration in each cycle was 6 min, the reverse electric field duration was 4 min, and the electrolysis time was 58 min to obtain LDH-coated liquid metal.

[0060] Step 5: Functionalization treatment: octadecylamine was dissolved in ethanol to prepare a 0.8 mol / L solution, ultrasonically dispersed at a power of 300 W and a frequency of 40 kHz for 30 minutes, and the pH was adjusted to 8.2 to prepare a functionalization reagent. The LDH-coated liquid metal was heated to 68°C at a heating rate of 2°C / min and kept warm. The pH was adjusted to 8.0 with 0.1M hydrochloric acid at a rate of 0.1 pH unit / min. The functionalization reagent was added (the weight ratio of the LDH-coated liquid metal functionalization reagent was 1:0.11), stirred at 200 rpm for 2.8 hours at 48°C, centrifuged at 2900 rpm for 19 minutes, washed with deionized water and anhydrous ethanol three times each, and vacuum dried at 59°C for 11.5 hours to obtain the liquid metal for the liquid cooling line coolant.

[0061] Comparative Example 1, compared with Example 1, lacks periodic electric field treatment.

[0062] Step 1: Prepare a liquid metal mixture: add 65 g of gallium, 21 g of indium, and 11 g of tin into a vacuum induction furnace, keep it at 765°C for 2.5 hours under argon protection, and then cool it to 22°C at a cooling rate of 6.5°C / min to obtain a liquid metal mixture.

[0063] Step 2: preparing liquid metal droplets: 100 g of the liquid metal mixture was mixed with 2000 g of deionized water containing 0.5 wt% polyvinyl pyrrolidone, centrifuged at 10,000 rpm for 17.5 min, and filtered through a nylon filter with a pore size of 125 μm to obtain liquid metal droplets.

[0064] Step 3. Prepare LDH precursor solution: Under nitrogen protection at 25°C, dissolve 7.75g of magnesium nitrate hexahydrate and 3.75g of aluminum nitrate nonahydrate in 500g of deionized water, stir and dissolve at 250rpm for 22.5min, adjust the pH to 9.45 with 0.5M sodium hydroxide solution, and then incubate in a water bath at 60°C under nitrogen protection for 11h to obtain an LDH precursor solution.

[0065] Step 4: DC electrolysis coating: The liquid metal droplets were mixed with the LDH precursor solution in a weight ratio of 1:4. A titanium mesh anode and a 316L stainless steel cathode were used with an electrode spacing of 20 mm. A constant DC voltage of 2.5 V was applied, and the current density was 0.75 A / dm². The electrolysis was continued for 52.5 min to obtain the LDH-coated liquid metal.

[0066] Step 5: Functionalization treatment: octadecylamine was dissolved in ethanol to prepare a 0.8 mol / L solution, ultrasonically dispersed at a power of 300 W and a frequency of 40 kHz for 30 minutes, and the pH was adjusted to 8.0 to prepare a functionalization reagent. The LDH-coated liquid metal was heated to 65°C at a heating rate of 2°C / min and kept warm. The pH was adjusted to 8.0 with 0.1M hydrochloric acid at a rate of 0.1 pH unit / min. The functionalization reagent was added (the weight ratio of the LDH-coated liquid metal functionalization reagent was 1:0.10), stirred at 200 rpm for 2.5 hours at 45°C, centrifuged at 2750 rpm for 17.5 minutes, washed twice with deionized water and anhydrous ethanol, and vacuum dried at 57.5°C for 11 hours to obtain the liquid metal for the liquid cooling line coolant.

[0067] Comparative Example 2, compared with Example 1, lacks the LDH coating layer.

[0068] Step 1: Prepare a liquid metal mixture: add 65 g of gallium, 21 g of indium, and 11 g of tin into a vacuum induction furnace, keep it at 765°C for 2.5 hours under argon protection, and then cool it to 22°C at a cooling rate of 6.5°C / min to obtain a liquid metal mixture.

[0069] Step 2: preparing liquid metal droplets: 100 g of the liquid metal mixture was mixed with 2000 g of deionized water containing 0.5 wt% polyvinyl pyrrolidone, centrifuged at 10,000 rpm for 17.5 min, and filtered through a nylon filter with a pore size of 125 μm to obtain liquid metal droplets.

[0070] Step 3: Direct functionalization: Dissolve octadecylamine in ethanol to prepare a 0.8 mol / L solution, ultrasonically disperse at 300 W power and 40 kHz frequency for 30 minutes, and adjust the pH to 8.0 to prepare a functionalization reagent. Heat the liquid metal droplet to 65°C at a heating rate of 2°C / min and keep it warm. Directly add the functionalization reagent (the weight ratio of LDH-coated liquid metal functionalization reagent is 1:0.10), stir at 200 rpm at 45°C for 2.5 hours, centrifuge at 2750 rpm for 17.5 minutes, wash twice with deionized water and anhydrous ethanol, and vacuum dry at 57.5°C for 11 hours to obtain the liquid metal for the liquid cooling line coolant.

[0071] Comparative Example 3: Compared with Example 1, the Ga-In-Sn ratio exceeds the scope to be protected by this application.

[0072] Step 1: Prepare a liquid metal mixture: add 75 g of gallium, 23 g of indium, and 8 g of tin into a vacuum induction furnace, keep it at 765°C for 2.5 hours under argon protection, and then cool it to 22°C at a cooling rate of 6.5°C / min to obtain a liquid metal mixture.

[0073] Step 2: preparing liquid metal droplets: 100 g of the liquid metal mixture was mixed with 2000 g of deionized water containing 0.5 wt% polyvinyl pyrrolidone, centrifuged at 10,000 rpm for 17.5 min, and filtered through a nylon filter with a pore size of 125 μm to obtain liquid metal droplets.

[0074] Step 3. Prepare LDH precursor solution: Under nitrogen protection at 25°C, dissolve 7.75g of magnesium nitrate hexahydrate and 3.75g of aluminum nitrate nonahydrate in 500g of deionized water, stir and dissolve at 250rpm for 22.5min, adjust the pH to 9.45 with 0.5M sodium hydroxide solution, and then incubate in a water bath at 60°C under nitrogen protection for 11h to obtain an LDH precursor solution.

[0075] Step 4: Electrolytic coating: The liquid metal droplets were mixed with the LDH precursor solution in a weight ratio of 1:4. A titanium mesh anode and a stainless steel 316L cathode were used. The electrode spacing was 20 mm. A DC voltage of 2.5 V was applied, the current density was 0.75 A / dm², the electric field cycle was 10 min, the forward electric field duration in each cycle was 6 min, the reverse electric field duration was 4 min, and the electrolysis time was 52.5 min to obtain LDH-coated liquid metal.

[0076] Step 5: Functionalization treatment: octadecylamine was dissolved in ethanol to prepare a 0.8 mol / L solution, ultrasonically dispersed at a power of 300 W and a frequency of 40 kHz for 30 minutes, and the pH was adjusted to 8.0 to prepare a functionalization reagent. The LDH-coated liquid metal was heated to 65°C at a heating rate of 2°C / min and kept warm. The pH was adjusted to 8.0 with 0.1M hydrochloric acid at a rate of 0.1 pH unit / min. The functionalization reagent was added (the weight ratio of the LDH-coated liquid metal functionalization reagent was 1:0.10), stirred at 200 rpm for 2.5 hours at 45°C, centrifuged at 2750 rpm for 17.5 minutes, washed twice with deionized water and anhydrous ethanol, and vacuum dried at 57.5°C for 11 hours to obtain the liquid metal for the liquid cooling line coolant.

[0077] Comparative Example 4: Compared with Example 1, the pH value exceeds the range to be protected in this application.

[0078] Step 1: Prepare a liquid metal mixture: add 65 g of gallium, 21 g of indium, and 11 g of tin into a vacuum induction furnace, keep it at 765°C for 2.5 hours under argon protection, and then cool it to 22°C at a cooling rate of 6.5°C / min to obtain a liquid metal mixture.

[0079] Step 2: preparing liquid metal droplets: 100 g of the liquid metal mixture was mixed with 2000 g of deionized water containing 0.5 wt% polyvinyl pyrrolidone, centrifuged at 10,000 rpm for 17.5 min, and filtered through a nylon filter with a pore size of 125 μm to obtain liquid metal droplets.

[0080] Step 3. Prepare LDH precursor solution: Under nitrogen protection at 25°C, dissolve 7.75g of magnesium nitrate hexahydrate and 3.75g of aluminum nitrate nonahydrate in 500g of deionized water, stir and dissolve at 250rpm for 22.5min, adjust the pH to 10.5 with 0.5M sodium hydroxide solution, and then incubate in a water bath at 60°C under nitrogen protection for 11h to obtain an LDH precursor solution.

[0081] Step 4: Electrolytic coating: The liquid metal droplets were mixed with the LDH precursor solution in a weight ratio of 1:4. A titanium mesh anode and a stainless steel 316L cathode were used. The electrode spacing was 20 mm. A DC voltage of 2.5 V was applied, the current density was 0.75 A / dm², the electric field cycle was 10 min, the forward electric field duration in each cycle was 6 min, the reverse electric field duration was 4 min, and the electrolysis time was 52.5 min to obtain LDH-coated liquid metal.

[0082] Step 5: Functionalization treatment: octadecylamine was dissolved in ethanol to prepare a 0.8 mol / L solution, ultrasonically dispersed at a power of 300 W and a frequency of 40 kHz for 30 minutes, and the pH was adjusted to 8.0 to prepare a functionalization reagent. The LDH-coated liquid metal was heated to 65°C at a heating rate of 2°C / min and kept warm. The pH was adjusted to 8.0 with 0.1M hydrochloric acid at a rate of 0.1 pH unit / min. The functionalization reagent was added (the weight ratio of the LDH-coated liquid metal functionalization reagent was 1:0.10), stirred at 200 rpm for 2.5 hours at 45°C, centrifuged at 2750 rpm for 17.5 minutes, washed twice with deionized water and anhydrous ethanol, and vacuum dried at 57.5°C for 11 hours to obtain the liquid metal for the liquid cooling line coolant.

[0083] Comparative Example 5: Compared with Example 1, the current density exceeds the scope to be protected by this application.

[0084] Step 1: Prepare a liquid metal mixture: add 65 g of gallium, 21 g of indium, and 11 g of tin into a vacuum induction furnace, keep it at 765°C for 2.5 hours under argon protection, and then cool it to 22°C at a cooling rate of 6.5°C / min to obtain a liquid metal mixture.

[0085] Step 2: preparing liquid metal droplets: 100 g of the liquid metal mixture was mixed with 2000 g of deionized water containing 0.5 wt% polyvinyl pyrrolidone, centrifuged at 10,000 rpm for 17.5 min, and filtered through a nylon filter with a pore size of 125 μm to obtain liquid metal droplets.

[0086] Step 3. Prepare LDH precursor solution: Under nitrogen protection at 25°C, dissolve 7.75g of magnesium nitrate hexahydrate and 3.75g of aluminum nitrate nonahydrate in 500g of deionized water, stir and dissolve at 250rpm for 22.5min, adjust the pH to 9.45 with 0.5M sodium hydroxide solution, and then incubate in a water bath at 60°C under nitrogen protection for 11h to obtain an LDH precursor solution.

[0087] Step 4: Electrolytic coating: Mix the liquid metal droplets with the LDH precursor solution in a weight ratio of 1:4, use a titanium mesh anode and a stainless steel 316L cathode, with an electrode spacing of 20 mm, apply a 2.5 V DC voltage, a current density of 1.5 A / dm², and an electric field cycle of 10 minutes. In each cycle, the forward electric field lasts for 6 minutes, the reverse electric field lasts for 4 minutes, and the electrolysis time is 52.5 minutes to obtain LDH-coated liquid metal.

[0088] Step 5: Functionalization treatment: octadecylamine was dissolved in ethanol to prepare a 0.8 mol / L solution, ultrasonically dispersed at a power of 300 W and a frequency of 40 kHz for 30 minutes, and the pH was adjusted to 8.0 to prepare a functionalization reagent. The LDH-coated liquid metal was heated to 65°C at a heating rate of 2°C / min and kept warm. The pH was adjusted to 8.0 with 0.1M hydrochloric acid at a rate of 0.1 pH unit / min. The functionalization reagent was added (the weight ratio of the LDH-coated liquid metal functionalization reagent was 1:0.10), stirred at 200 rpm for 2.5 hours at 45°C, centrifuged at 2750 rpm for 17.5 minutes, washed twice with deionized water and anhydrous ethanol, and vacuum dried at 57.5°C for 11 hours to obtain the liquid metal for the liquid cooling line coolant.

[0089] Comparative Example 6, compared with Example 1, lacks a functionalizing agent.

[0090] Step 1: Prepare a liquid metal mixture: add 65 g of gallium, 21 g of indium, and 11 g of tin into a vacuum induction furnace, keep it at 765°C for 2.5 hours under argon protection, and then cool it to 22°C at a cooling rate of 6.5°C / min to obtain a liquid metal mixture.

[0091] Step 2: preparing liquid metal droplets: 100 g of the liquid metal mixture was mixed with 2000 g of deionized water containing 0.5 wt% polyvinyl pyrrolidone, centrifuged at 10,000 rpm for 17.5 min, and filtered through a nylon filter with a pore size of 125 μm to obtain liquid metal droplets.

[0092] Step 3. Prepare LDH precursor solution: Under nitrogen protection at 25°C, dissolve 7.75g of magnesium nitrate hexahydrate and 3.75g of aluminum nitrate nonahydrate in 500g of deionized water, stir and dissolve at 250rpm for 22.5min, adjust the pH to 9.45 with 0.5M sodium hydroxide solution, and then incubate in a water bath at 60°C under nitrogen protection for 11h to obtain an LDH precursor solution.

[0093] Step 4: Electrolytic coating: The liquid metal droplets were mixed with the LDH precursor solution in a weight ratio of 1:4. A titanium mesh anode and a stainless steel 316L cathode were used. The electrode spacing was 20 mm. A DC voltage of 2.5 V was applied, the current density was 0.75 A / dm², the electric field cycle was 10 min, the forward electric field duration in each cycle was 6 min, the reverse electric field duration was 4 min, and the electrolysis time was 52.5 min to obtain LDH-coated liquid metal.

[0094] Step 5, direct treatment: The LDH-coated liquid metal was heated to 65°C at a heating rate of 2°C / min and kept warm, and the pH was adjusted to 8.0 with 0.1M hydrochloric acid at a rate of 0.1pH unit / min, stirred at 200rpm for 2.5h at 45°C, centrifuged at 2750rpm for 17.5min, washed twice with deionized water and anhydrous ethanol, and vacuum dried at 57.5°C for 11h to obtain liquid metal for liquid cooling line coolant.

[0095] Comparative Example 7: Compared with Example 1, the insulation temperature exceeds the range to be protected by this application.

[0096] Step 1: Prepare a liquid metal mixture: add 65 g of gallium, 21 g of indium, and 11 g of tin into a vacuum induction furnace, keep it at 900°C for 2.5 hours under argon protection, and then cool it to 22°C at a cooling rate of 6.5°C / min to obtain a liquid metal mixture.

[0097] Step 2: preparing liquid metal droplets: 100 g of the liquid metal mixture was mixed with 2000 g of deionized water containing 0.5 wt% polyvinyl pyrrolidone, centrifuged at 10,000 rpm for 17.5 min, and filtered through a nylon filter with a pore size of 125 μm to obtain liquid metal droplets.

[0098] Step 3. Prepare LDH precursor solution: Under nitrogen protection at 25°C, dissolve 7.75g of magnesium nitrate hexahydrate and 3.75g of aluminum nitrate nonahydrate in 500g of deionized water, stir and dissolve at 250rpm for 22.5min, adjust the pH to 9.45 with 0.5M sodium hydroxide solution, and then incubate in a water bath at 60°C under nitrogen protection for 11h to obtain an LDH precursor solution.

[0099] Step 4: Electrolytic coating: The liquid metal droplets were mixed with the LDH precursor solution in a weight ratio of 1:4. A titanium mesh anode and a stainless steel 316L cathode were used. The electrode spacing was 20 mm. A DC voltage of 2.5 V was applied, the current density was 0.75 A / dm², the electric field cycle was 10 min, the forward electric field duration in each cycle was 6 min, the reverse electric field duration was 4 min, and the electrolysis time was 52.5 min to obtain LDH-coated liquid metal.

[0100] Step 5: Functionalization treatment: octadecylamine was dissolved in ethanol to prepare a 0.8 mol / L solution, ultrasonically dispersed at a power of 300 W and a frequency of 40 kHz for 30 minutes, and the pH was adjusted to 8.0 to prepare a functionalization reagent. The LDH-coated liquid metal was heated to 65°C at a heating rate of 2°C / min and kept warm. The pH was adjusted to 8.0 with 0.1M hydrochloric acid at a rate of 0.1 pH unit / min. The functionalization reagent was added (the weight ratio of the LDH-coated liquid metal functionalization reagent was 1:0.10), stirred at 200 rpm for 2.5 hours at 45°C, centrifuged at 2750 rpm for 17.5 minutes, washed twice with deionized water and anhydrous ethanol, and vacuum dried at 57.5°C for 11 hours to obtain the liquid metal for the liquid cooling line coolant.

[0101] Comparative Example 8: Compared with Example 1, the ratio of the functionalized reagent exceeds the scope to be protected by this application.

[0102] Step 1: Prepare a liquid metal mixture: add 65 g of gallium, 21 g of indium, and 11 g of tin into a vacuum induction furnace, keep it at 765°C for 2.5 hours under argon protection, and then cool it to 22°C at a cooling rate of 6.5°C / min to obtain a liquid metal mixture.

[0103] Step 2: preparing liquid metal droplets: 100 g of the liquid metal mixture was mixed with 2000 g of deionized water containing 0.5 wt% polyvinyl pyrrolidone, centrifuged at 10,000 rpm for 17.5 min, and filtered through a nylon filter with a pore size of 125 μm to obtain liquid metal droplets.

[0104] Step 3. Prepare LDH precursor solution: Under nitrogen protection at 25°C, dissolve 7.75g of magnesium nitrate hexahydrate and 3.75g of aluminum nitrate nonahydrate in 500g of deionized water, stir and dissolve at 250rpm for 22.5min, adjust the pH to 9.45 with 0.5M sodium hydroxide solution, and then incubate in a water bath at 60°C under nitrogen protection for 11h to obtain an LDH precursor solution.

[0105] Step 4: Electrolytic coating: The liquid metal droplets were mixed with the LDH precursor solution in a weight ratio of 1:4. A titanium mesh anode and a stainless steel 316L cathode were used. The electrode spacing was 20 mm. A DC voltage of 2.5 V was applied, the current density was 0.75 A / dm², the electric field cycle was 10 min, the forward electric field duration in each cycle was 6 min, the reverse electric field duration was 4 min, and the electrolysis time was 52.5 min to obtain LDH-coated liquid metal.

[0106] Step 5: Functionalization treatment: octadecylamine was dissolved in ethanol to prepare a 0.8 mol / L solution, ultrasonically dispersed at a power of 300 W and a frequency of 40 kHz for 30 minutes, and the pH was adjusted to 8.0 to prepare a functionalization reagent. The LDH-coated liquid metal was heated to 65°C at a heating rate of 2°C / min and kept warm. The pH was adjusted to 8.0 with 0.1M hydrochloric acid at a rate of 0.1 pH unit / min. The functionalization reagent was added (the weight ratio of the LDH-coated liquid metal functionalization reagent was 1:0.2), stirred at 200 rpm for 2.5 hours at 45°C, centrifuged at 2750 rpm for 17.5 minutes, washed twice with deionized water and anhydrous ethanol, and vacuum dried at 57.5°C for 11 hours to obtain the liquid metal for the liquid cooling line coolant.

[0107] Performance testing

[0108] 1. Thermal conductivity test

[0109] Test equipment: Laser flash thermal conductivity tester (LFA457)

[0110] Test step 1: Place the liquid metal sample into a graphite crucible with a diameter of 12.7 mm and a thickness of 2 to 3 mm, ensuring that the sample thickness is uniform.

[0111] Test step 2: Spray a graphite coating on the sample surface with a thickness of about 10-20μm to improve the surface absorptivity and emissivity.

[0112] Test step three: Place the sample in the test furnace and introduce argon protective atmosphere at a flow rate of 50ml / min to eliminate the influence of oxygen.

[0113] Test step 4: Set the laser pulse energy to 12 J, the pulse width to 0.8 ms, and the detector sampling frequency to 1 MHz.

[0114] Test step 5: Test at a constant temperature of 25°C. Test each sample 5 times with an interval of 10 minutes between tests.

[0115] Test step six: Use the Cape-Lehman model to fit the temperature rise curve, calculate the thermal diffusivity, and calculate the thermal conductivity based on the specific heat capacity and density.

[0116] 2. Conductivity test

[0117] Test equipment: Precision LCR meter with four-probe test fixture

[0118] Test step 1: Pour liquid metal into a polytetrafluoroethylene test tank with a length of 50 mm, a width of 5 mm, and a height of 2 mm.

[0119] Test step 2: Insert four platinum wire electrodes with a diameter of 0.5 mm, with a distance of 40 mm between the two outer electrodes and a distance of 20 mm between the two inner electrodes.

[0120] Test step 3: Set the test current to 100mA and the frequency to 1kHz to avoid the influence of electrochemical reaction.

[0121] Test step 4: Start the test after stabilizing at a constant temperature of 25°C for 10 minutes.

[0122] Test step 5: Test continuously for 60 seconds, record the resistance value every 5 seconds, and test each sample 3 times.

[0123] Test Step 6: Calculate the conductivity based on the geometric dimensions and Ohm's law: σ = L / (R x A), where L is the electrode spacing and A is the cross-sectional area.

[0124] 3. Long-term stability test

[0125] Test step 1: Seal 50 ml of sample in glass ampoules and fill them with argon for protection.

[0126] Test step 2: The samples were stored in thermostats at -40°C, 25°C, and 80°C for 90 days.

[0127] Test step three: Take out the samples every 15 days, return them to room temperature, and then test the thermal conductivity and electrical conductivity.

[0128] Test step 4: Observe the changes in the sample's appearance and record whether phase separation, oxidation, or precipitation occurs.

[0129] Test step 5: Calculate the performance retention rate: η = (Pt / P0) x 100%, where P0 is the initial performance and Pt is the performance after t time.

[0130] 4. Viscosity and rheological properties test

[0131] Test equipment: Rotational rheometer (Anton Paar MCR302)

[0132] Test step 1: Use parallel plate geometry, 1mm plate spacing, and test temperature of 25°C.

[0133] Test step 2: Pre-shear treatment: Shear for 60 seconds at a shear rate of 100 s-1 and let it stand for 120 seconds to eliminate the shear history.

[0134] Test step 3: Perform steady-state shear test with a shear rate of 0.1s -1 Increased to 1000s -1 , each point is tested for 30 seconds.

[0135] Test step 4: Perform a frequency sweep test with a frequency range of 0.1 to 100 Hz and a strain amplitude of 1%.

[0136] Test step 5: Test temperature dependence, temperature range 15-85°C, heating rate 2°C / min.

[0137] 5. Thermal cycle stability test

[0138] Test step 1: Place the sample into a sealed stainless steel test tube and fill the tube with argon gas for protection.

[0139] Test step 2: Set the thermal cycle program: from room temperature to 80℃ and hold for 1 hour, then drop to -20℃ and hold for 1 hour, which is one cycle.

[0140] Test step three: Perform 500 thermal cycles continuously, taking samples for testing every 50 cycles.

[0141] Test step 4: Test the changes in thermal conductivity, electrical conductivity and viscosity at each cycle node.

[0142] Test Step 5: Analyze the impact of thermal cycling on the microstructure and evaluate long-term reliability.

[0143] 6. Material compatibility test

[0144] Test step 1: Select common cooling pipe materials: pure copper (T2), 6061 aluminum alloy, 304 stainless steel, and make a 30x10x2mm test piece.

[0145] Test step 2: Polish the surface of the test piece to Ra no more than 0.4μm, and clean and degrease it with anhydrous ethanol and acetone in sequence.

[0146] Test step three: The test piece is completely immersed in liquid metal and an accelerated corrosion test is performed in a 60°C constant temperature box.

[0147] Test step 4: Remove the test pieces after 7 days, 30 days, and 90 days, and perform ultrasonic cleaning to remove residual liquid metal.

[0148] Test data table

[0149] Table 1. Thermal conductivity test results (W / m·K, 25°C)

[0150]

[0151] Table 2. Conductivity test results (×10 6 S / m, 25℃)

[0152]

[0153] Table 3. 90-day long-term stability test results (performance retention %)

[0154]

[0155] Table 4. Viscosity test results (mPa·s, 25°C, shear rate 100s -1 )

[0156]

[0157] Table 5. Performance change rate after 500 thermal cycles (%)

[0158]

[0159] Table 6. 90-day material compatibility test results (corrosion rate mg / cm²·d, 60°C)

[0160]

[0161] Data Analysis

[0162] As can be seen from Table 1, the thermal conductivity of the embodiments of the present invention is significantly better than that of all comparative examples. The thermal conductivity of Example 3 is as high as 49.7 W / m·K, which is 47.0% higher than that of Comparative Example 2 (33.8 W / m·K), which has the lowest thermal conductivity. The thermal conductivity of Example 1 is 48.3 W / m·K, which is 17.2%, 42.9%, 8.5%, 25.1%, 12.1%, 33.4%, 18.4%, and 22.6% higher than that of Comparative Examples 1-8, respectively. The effect of periodic electric field treatment is reflected in the difference between Comparative Example 1 and DC electrolysis. The thermal conductivity of Example 1 is increased by 17.2% compared with Comparative Example 1, indicating that the periodic electric field can optimize the density and crystallinity of the LDH coating layer and reduce the interfacial thermal resistance. The thermal conductivity of Comparative Example 2, which lacks LDH coating, decreases most significantly, indicating that the LDH layer not only provides protection, but its layered structure can also improve the phonon transmission path and significantly improve the thermal conductivity performance. The standard deviations of the examples are all less than 0.5, which are much lower than 0.7-1.3 of the comparative examples, indicating that the preparation process of the present invention has better reproducibility and thermal performance stability.

[0163] As can be seen from Table 2, the embodiments of the present invention have obvious advantages in terms of conductivity. The highest conductivity of embodiment 3 is 3.72×10 6 S / m (corresponding to a resistivity of 26.9 μΩ·cm), which is lower than the comparative example 2 with the lowest conductivity (2.58×10 6 S / m, resistivity 38.8μΩ·cm) is 44.2% higher. The conductivity of Example 1 is 3.64×10 6S / m, which is 16.7%, 41.1%, 8.7%, 26.0%, 11.7%, 34.3%, 14.5%, and 23.8% higher than the control examples, respectively. From the perspective of resistivity, the 27.5μΩ·cm of Example 1 is close to the theoretical value of pure Ga-In-Sn alloy (about 25-28μΩ·cm), while the 38.8μΩ·cm of Comparative Example 2 indicates a significant increase in interface resistance. The LDH coating provides a continuous conductive path for electron transport through its unique layered structure and good conductivity. At the same time, the periodic electric field treatment optimizes the bonding state between the coating and the liquid metal interface, reducing the contact resistance. The conductivity of Comparative Example 4 with an excessively high pH value and Comparative Example 6 without a functionalized reagent decreased significantly, indicating the importance of a suitable chemical environment for maintaining excellent electrical properties.

[0164] As can be seen from Table 3, Example 1 of the present invention has significant advantages in long-term stability. Under the worst environment of 80°C, the thermal conductivity and electrical conductivity retention rates of Example 1 still reached 94.2% and 93.1% respectively, while those of Comparative Example 1 were only 84.9% and 82.6%, and those of Comparative Example 2 dropped to 74.6% and 71.9%. Under low temperature conditions of -40°C, the performance retention rates of Example 1 were 96.8% and 95.4%, which were significantly better than 88.5% and 86.1% of Comparative Example 1, and 79.3% and 76.8% of Comparative Example 2. The stability test at room temperature of 25°C showed that Example 1 performed best, with performance retention rates of 98.9% and 98.2% after 90 days. This excellent stability is mainly attributed to the protective effect of the LDH coating layer, whose interlayer anions (CO3 2- OH - ) can inhibit the oxidation of liquid metal, while the dense coating structure formed by periodic electric field treatment further enhances environmental adaptability. Comparative Example 2, due to the lack of a protective layer, experienced significant phase separation and surface oxidation during temperature changes, resulting in rapid performance degradation.

[0165] As shown in Table 4, the viscosity and rheological properties of the examples of the present invention are significantly superior to those of the comparative examples. Example 3 exhibits the lowest viscosity, 1.85 mPa·s, 55.4% lower than the highest viscosity of Comparative Example 2 (4.15 mPa·s). Example 1 exhibits a viscosity of 1.92 mPa·s, representing decreases of 29.7%, 53.7%, 15.8%, 36.4%, 25.6%, 48.9%, 23.5%, and 41.6% compared to Comparative Examples 1-8, respectively. Analysis of the flow index n value shows that the examples exhibit n values ​​close to 1 (0.97-0.99), demonstrating near-Newtonian fluid behavior, while the n values ​​of the comparative examples drop to 0.89-0.96, indicating some shear-thinning behavior. The lubricating effect of the LDH coating and the surface modification effect of the functionalized reagent synergistically reduce interparticle friction. Furthermore, the uniform coating formed by the periodic electric field treatment prevents the increase in viscosity caused by localized agglomeration. The viscosity of Comparative Example 2, which lacks LDH coating, surges to 4.15 mPa·s, indicating strong van der Waals forces and surface tension between exposed liquid metal particles. The optimal viscosity facilitates circulation in the cooling system, reducing pumping power and improving heat transfer efficiency.

[0166] As can be seen from Table 5, the 500 thermal cycle tests further verified the long-term reliability advantage of the present invention. After 500 thermal cycles from -20°C to 80°C, the thermal conductivity and electrical conductivity of Example 1 only decreased by 2.1% and 1.8%, respectively, and the viscosity increased by 1.6%, with minimal performance changes. In contrast, the performance of Comparative Example 1 decreased by 5.9% to 6.4%, while the performance of Comparative Example 2, which lacked protection, was the most severely attenuated, with a decrease in thermal conductivity of 12.3%, a decrease in electrical conductivity of 11.7%, and an increase in viscosity of 9.3%. Repeated thermal expansion and contraction during thermal cycling will generate stress at the material interface, leading to the initiation and expansion of microcracks. The LDH coating has certain flexibility and self-healing ability, which can relieve thermal stress and inhibit crack propagation, and the functionalized reagent further enhances the interfacial bonding strength. Although Comparative Example 6 has LDH coating but lacks functionalization treatment, its thermal cycling performance is between the embodiment and the severely defective comparative example, which proves the important role of functionalization in improving thermal cycling stability.

[0167] As can be seen from Table 6, Example 1 of the present invention has extremely low corrosion resistance to commonly used cooling pipes, demonstrating excellent material compatibility. The corrosion rate for pure copper is only 0.0085 mg / cm²·d, which is 55.7% lower than that of Comparative Example 1, 75.6% lower than that of Comparative Example 2, and 68.2% lower than that of Comparative Example 6. The corrosion rates for 6061 aluminum alloy and 304 stainless steel are 0.0063 and 0.0041 mg / cm²·d, respectively, which are also significantly lower than those of the comparative examples. According to industrial standards, a corrosion rate below 0.01 mg / cm²·d is considered an excellent compatibility level, and Example 1 fully meets this requirement. The layered structure of LDH can effectively block direct contact between liquid metal and pipes, while the organic protective film formed by the functionalized reagent further reduces the driving force of electrochemical corrosion. Comparative Example 2, which lacks a protective layer, is the most corrosive, especially for copper, with a corrosion rate of up to 0.0348 mg / cm²·d, which can lead to rapid damage to the piping system and coolant contamination. Obviously, the technical solution of this application significantly improves the application scope and engineering application value of liquid metal coolant.

[0168] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A liquid metal for liquid cooling line coolant, characterized in that Prepared by the following steps: Step 1: mixing the liquid metal mixture with deionized water containing polyvinyl pyrrolidone, centrifuging, and filtering to obtain liquid metal droplets; Step 2: Dissolve magnesium nitrate hexahydrate and aluminum nitrate nonahydrate in deionized water at 20-30°C under nitrogen protection, stir to dissolve, adjust the pH to 9.2-9.7 with 0.5M sodium hydroxide solution, and then incubate in a water bath at 60°C under nitrogen protection for 10-12 hours to obtain an LDH precursor solution; Step 3: mixing the liquid metal droplets with the LDH precursor solution, applying a periodic electric field for electrolysis, and obtaining the LDH-coated liquid metal; Step 4: Heat and keep the LDH-coated liquid metal warm, adjust the pH to 8.0 with 0.1M hydrochloric acid, add a functionalizing reagent, stir, centrifuge, wash 2-3 times with deionized water or anhydrous ethanol, and vacuum dry to obtain liquid metal for liquid cooling line coolant; The functionalization reagent is prepared by dissolving octadecylamine in ethanol to prepare a 0.8 mol / L solution, ultrasonically dispersing the solution at a power of 300 W and a frequency of 40 kHz for 30 minutes, and adjusting the pH to 7.5-8.

5.

2. The liquid metal for liquid cooling line coolant according to claim 1, characterized in that: The liquid metal mixture is prepared by the following steps: adding gallium, indium and tin into a vacuum induction furnace, keeping the temperature under argon protection, and then cooling to 15-30° C. to obtain the liquid metal mixture.

3. The liquid metal for liquid cooling line coolant according to claim 2, characterized in that: The weight ratio of gallium, indium and tin is 60-70:20-22:10-12, the holding temperature is 750-780° C., the holding time is 2-3 hours, and the cooling rate is 5-8° C. / min.

4. The liquid metal for liquid cooling line coolant according to claim 1, characterized in that: The mass fraction of polyvinyl pyrrolidone in the deionized water containing polyvinyl pyrrolidone is 0.5 wt %.

5. The liquid metal for liquid cooling line coolant according to claim 1, characterized in that: In the step 1, the centrifugal speed is 8000-12000 rpm, the centrifugal time is 15-20 min, and the filtration is performed using a nylon filter or a stainless steel filter with a pore size of 50-200 μm.

6. The liquid metal for liquid cooling line coolant according to claim 1, characterized in that: In the step 2, the weight ratio of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and deionized water is 7.5-8.0:3.7-3.8:500, the stirring rate of the stirring dissolution is 200-300 rpm, and the stirring time is 15-30 min.

7. The liquid metal for liquid cooling line coolant according to claim 1, characterized in that: In the step 3, the weight ratio of the liquid metal droplets to the LDH precursor solution is 1:3-5.

8. The liquid metal for liquid cooling line coolant according to claim 1, characterized in that: The periodic electric field parameters are as follows: a titanium mesh anode and a stainless steel 316L cathode, an electrode spacing of 20 mm, an applied DC voltage of 2.5 V, a current density of 0.5-1.0 A / dm², an electric field cycle of 10 minutes, a forward electric field duration of 6 minutes in each cycle, a reverse electric field duration of 4 minutes, and an electrolysis time of 45-60 minutes.

9. The liquid metal for liquid cooling line coolant according to claim 1, characterized in that: In the step 4, the weight ratio of the LDH-coated liquid metal to the functionalizing reagent is 1:0.08~0.12, the heating and insulation heating rate is 2°C / min, the insulation temperature is 60~70°C, the pH adjustment rate is 0.1 pH unit / min, the stirring temperature is 40~50°C, the stirring time is 2~3h, the stirring rate is 200rpm, the centrifugal rate is 2500~3000rpm, the centrifugal time is 15~20min, and the vacuum drying is vacuum drying at 55~60°C for 10~12h.

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