Liquid metal for liquid cooling line cooling liquid

Abstract

The invention discloses liquid metal for liquid cooling line cooling liquid, and belongs to the technical field of liquid metal materials, liquid metal mixed liquid and deionized water containing polyvinylpyrrolidone are mixed, centrifuged and filtered, and liquid metal microdroplets are obtained; mixing the liquid metal microdroplets with the LDH precursor solution, and applying a periodic electric field for electrolysis to obtain LDH-coated liquid metal; the LDH coated liquid metal is heated and subjected to heat preservation, the pH is adjusted to 8.0 with 0.1 M hydrochloric acid, a functional reagent is added, stirring and centrifugation are conducted, washing is conducted 2-3 times with deionized water or absolute ethyl alcohol, vacuum drying is conducted, and the liquid metal for the liquid cooling line cooling liquid is obtained. The liquid metal for the liquid cooling line cooling liquid with high thermal conductivity is prepared, the corrosion performance of the liquid metal is reduced, the thermal cycle stability and the heat transfer efficiency are improved, the liquid metal has excellent long-term stability, and the application range and the engineering application value of the liquid metal cooling liquid are remarkably improved.

Description

Technical Field

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

[0002] Liquid metal coolants are a class of advanced heat transfer media based on low melting point metals or alloys. Their unique physical and chemical properties make them show great potential in the field of electronic device thermal management. The excellent heat transfer performance of liquid metals stems from the free electron sea in their metallic bond structure. These high-mobility electrons not only provide excellent electrical conductivity, but more importantly, according to the Wiedemann-Franz law (κ = LσT), endow the material with extremely high thermal conductivity. Taking the typical ternary eutectic alloy of gallium, indium and tin (Galinstan) as an example, its thermal conductivity at room temperature can reach 16.5 - 26.4 W / m·K, which is more than an order of magnitude higher than that of traditional organic coolants. Liquid metals also have advantages such as near-zero vapor pressure, wide liquid temperature range, high heat capacity (130 - 160 J / kg·K), etc., and theoretically can achieve efficient and stable phase change cooling. From a microscopic perspective, the heat transfer mechanism of liquid metals includes the synergistic effect of electron conduction, phonon conduction and convective mass transfer, among which electron conduction dominates, enabling liquid metals to achieve rapid heat transfer at a relatively low temperature gradient. 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 in dealing with high heat flux density electronic devices.

[0003] However, the existing liquid metal cooling technology still faces many severe technical challenges, which seriously limit its engineering applications. First, the problem of hydrodynamic control is prominently manifested in the high fluidity and low viscosity (about 2 mPa·s) of traditional gallium-based alloys at room temperature. Although this property is beneficial to convective heat transfer, it causes serious difficulties in flow direction control and leakage risk in practical applications. Especially in microchannels or complex geometries, liquid metals are prone to unexpected flow and aggregation phenomena. Second, the problem of interface compatibility stems from the complex physical and chemical interactions between liquid metals and solid materials, including poor wetting (contact angle is usually greater than 120°), interface corrosion, formation of intermetallic compounds, etc. These problems will lead to an increase in interface thermal resistance and a decrease in structural integrity. For example, when gallium-based liquid metal contacts with aluminum alloy, brittle intermetallic compounds such as Al2Ga3 and Al5Ga2 will be formed, triggering the phenomenon of liquid metal embrittlement (LME), which seriously threatens the system reliability. The intrinsic contradiction between thermal conduction efficiency and material stability is also very prominent: high thermal conductivity requires high electron density and strong metallicity, but this also means high chemical activity and tendency of interface reaction; while adding stabilizing elements or forming a protective oxide film can improve stability, but it will significantly reduce the thermal conduction performance. In terms of preparation process, traditional melting and mixing methods are difficult to precisely control the microstructure and compositional uniformity of multi-element alloys, and are prone to defects such as compositional 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 the reference CN119571177B has achieved certain temperature-controlled phase change characteristics through the co-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 it extremely difficult to optimize the composition and predict the phase structure, and it is difficult to achieve precise performance regulation. The introduction of heavy metal elements Cd and Pb can lower the melting point of the alloy, but it seriously violates the concept of modern green manufacturing and does not meet international environmental protection standards such as RoHS, restricting its application prospects in fields such as consumer electronics. The traditional melting and mixing process shows obvious technical bottlenecks when dealing with multi-element systems: the huge density difference between different elements (such as the density of Pb is 11.34 g / cm³ and the density of Al is 2.70 g / cm³) leads to serious gravitational segregation; the large difference in melting points of each element (the melting point of Al is 660 °C and the melting point of Sn is 232 °C) makes it difficult to carry out homogenization treatment; the oxidation loss of active elements during the high-temperature melting process is difficult to control, and the compositional reproducibility between batches is poor. In addition, this technology has not fundamentally solved the core technical problems of liquid metals, such as improving interface wettability, ensuring long-term cycle stability, cost control, etc., and is still in the laboratory concept verification stage, with a large gap from industrial application. Summary of the Invention

[0005] To address the deficiencies of the prior art, the present invention prepares a liquid metal for use as a liquid coolant for a liquid-cooled wire by restricting the components and content of the liquid metal composition, combining it with an LDH precursor solution for surface modification, and subjecting it to surface treatment with a functionalizing reagent, achieving an overall improvement in thermal conductivity, electrical conductivity, and corrosion resistance, and having excellent long-term stability.

[0006] The present invention protects a liquid metal for use as a liquid coolant for a liquid-cooled wire, which is prepared by the following steps: Step 1: Mix the liquid metal mixture with deionized water containing polyvinylpyrrolidone, centrifuge, and filter to obtain liquid metal microdroplets. It can be understood that in this application, polyvinylpyrrolidone is added as a nonionic surfactant to prevent the coalescence of liquid metal through steric hindrance effects.

[0007] Step 2: Under nitrogen protection at 20 - 30°C, dissolve magnesium nitrate hexahydrate and aluminum nitrate nonahydrate in deionized water, stir to dissolve, adjust the pH to 9.2 - 9.7 with 0.5M sodium hydroxide solution, and then perform a water bath at 60°C for 10 - 12 hours under nitrogen protection to obtain an LDH precursor solution. It can be understood that under alkaline conditions, Mg 2+ and Al 3+ form a layered double hydroxide [Mg 1-x Al x (OH)2] x+ structure; based on the solubility product constant, this application controls the pH to 9.2 - 9.7 to ensure complete coprecipitation and avoid the formation of single-phase hydroxides; by controlling the temperature at 60°C for hydrothermal treatment to promote crystal perfection, a regular layered structure is formed.

[0008] Step 3: Mix the liquid metal microdroplets with the LDH precursor solution, apply a periodic electric field for electrolysis to obtain LDH-coated liquid metal. It can be understood that in this application, a continuous conductive path is constructed through the LDH coating layer, eliminating the contact potential barrier and reducing the interfacial resistance, thereby improving the electrical conductivity of the liquid metal; the LDH layered structure channels optimize the phonon transmission path and reduce interfacial scattering, thereby improving the thermal conductivity of the liquid metal.

[0009] 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 absolute ethanol, and vacuum dry to obtain the liquid metal for use as a liquid coolant for a liquid-cooled wire.

[0010] Preferably, the liquid metal mixture is prepared by the following steps: adding gallium, indium and tin into a vacuum induction furnace, keeping warm under argon protection, and then cooling to 15-30°C to obtain the liquid metal mixture.

[0011] Preferably, the weight ratio of gallium, indium and tin is 60-70:20-22:10-12, the heat preservation temperature is 750-780°C, the heat preservation time is 2-3 h, and the cooling rate is 5-8°C / min.

[0012] It can be understood that in this application, a low-melting eutectic alloy is formed by controlling the ratio of the Ga-In-Sn system, which remains liquid at room temperature and conforms to the Eu-Gibbs law; the heat preservation temperature is controlled far above the melting points of each component to ensure complete melting and atomic-level uniform mixing; the cooling rate is controlled to avoid rapid solidification and component segregation, and a uniform microstructure is obtained.

[0013] Preferably, the mass fraction of polyvinylpyrrolidone in the deionized water containing polyvinylpyrrolidone is 0.5 wt%.

[0014] Preferably, in the first step, the centrifugation rate is 8000-12000 rpm, the centrifugation time is 15-20 min, and the filtration is carried out using a nylon filter or a stainless steel filter with a pore size of 50-200 μm.

[0015] It can be understood that in this application, strong shear force is generated by high-speed centrifugation to break large liquid metals into micron-sized droplets; the pore size of the filter is controlled to ensure particle size uniformity, providing an ideal substrate for subsequent coating.

[0016] Preferably, in the second step, 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 for stirring and dissolving is 200-300 rpm, and the stirring time is 15-30 min.

[0017] Preferably, in the third step, the weight ratio of the liquid metal microdroplets to the LDH precursor solution is 1:3-5.

[0018] Preferably, the periodic electric field parameters are as follows: using a titanium mesh anode and a stainless steel 316L cathode, the electrode spacing is 20 mm, a DC voltage of 2.5 V is applied, the current density is 0.5-1.0 A / dm², the electric field period is 10 min, the duration of the positive electric field in each period is 6 min, the duration of the negative electric field is 4 min, and the electrolysis time is 45-60 min.

[0019] It can be understood that in this application, the positive electric field is used to promote the migration of the positively charged LDH precursor to the cathode (the surface of the liquid metal), and the negative electric field is used to eliminate concentration polarization to ensure that the coating layer is uniform and dense.

[0020] Preferably, the functionalizing reagent is prepared by dissolving octadecylamine in ethanol to form a 0.8 mol / L solution, ultrasonic dispersing it for 30 min at a power of 300 W and a frequency of 40 kHz, and adjusting the pH to 7.5 - 8.5.

[0021] It can be understood that the octadecylamine added in this application forms an ordered molecular film on the surface of LDH through van der Waals forces, with the long-chain 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.

[0022] Preferably, in the fourth step, the weight ratio of the LDH-coated liquid metal to the functionalizing reagent is 1:0.08 - 0.12, the heating rate for heat preservation is 2 °C / min, the heat preservation temperature is 60 - 70 °C, the rate of adjusting the pH is 0.1 pH unit / min, the stirring temperature is 40 - 50 °C, the stirring time is 2 - 3 h, the stirring rate is 200 rpm, the centrifugation rate is 2500 - 3000 rpm, the centrifugation time is 15 - 20 min, and the vacuum drying is carried out at 55 - 60 °C for 10 - 12 h.

[0023] The present invention has the following beneficial effects: (1) The present invention optimizes the phonon transmission path through the LDH layered structure, combines the treatment with a periodic electric field to reduce the interfacial thermal resistance, and improves the thermal conductivity of the liquid metal; constructs a continuous conductive path through the LDH coating layer to reduce the contact resistance and significantly improves the electrical conductivity of the liquid metal; reduces the corrosiveness of the liquid metal through the synergistic effect of the LDH barrier layer and the functionalized protective film, expanding the scope of industrial applications; effectively alleviates the thermal stress through the multi-level structure and improves the thermal cycle stability of the liquid metal.

[0024] (2) The technical solution of the present invention selects the treatment with a periodic electric field to achieve precise control, has excellent preparation reproducibility, and is suitable for large-scale industrial applications. Detailed Embodiments

[0025] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0026] Example 1 Step 1. Prepare a liquid metal mixture: Add 65 g of gallium, 21 g of indium, and 11 g of tin to a vacuum induction furnace, keep it at 765 °C for 2.5 h 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.

[0027] Step 2: Preparation of liquid metal microdroplets: Mix 100 g of liquid metal mixture with 2000 g of deionized water containing 0.5 wt% of polyvinylpyrrolidone, centrifuge at 10000 rpm for 17.5 min, and filter through a nylon filter with a pore size of 125 μm to obtain liquid metal microdroplets.

[0028] Step 3: Preparation of LDH precursor solution: Under nitrogen protection at 25 °C, dissolve 7.75 g of magnesium nitrate hexahydrate and 3.75 g of aluminum nitrate nonahydrate in 500 g of deionized water, stir and dissolve at 250 rpm for 22.5 min, adjust the pH to 9.45 with 0.5 M sodium hydroxide solution, and then carry out a water bath at 60 °C for 11 h under nitrogen protection to obtain the LDH precursor solution.

[0029] Step 4: Electrolytic coating: Mix the liquid metal microdroplets and the LDH precursor solution at 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 DC voltage of 2.5 V, a current density of 0.75 A / dm², an electric field period of 10 min, with the forward electric field duration of 6 min and the reverse electric field duration of 4 min in each period, and an electrolysis time of 52.5 min to obtain LDH-coated liquid metal.

[0030] Step 5: Functionalization treatment: Dissolve octadecylamine in ethanol to prepare a 0.8 mol / L solution, disperse it by ultrasonic wave at a power of 300 W and a frequency of 40 kHz for 30 min, and adjust the pH to 8.0 to obtain a functionalization reagent. Heat the LDH-coated liquid metal at a heating rate of 2 °C / min to 65 °C and keep it warm, adjust the pH to 8.0 at a rate of 0.1 pH unit / min with 0.1 M hydrochloric acid, add the functionalization reagent (the weight ratio of the LDH-coated liquid metal to the functionalization reagent is 1:0.10), stir at 200 rpm at 45 °C for 2.5 h, centrifuge at 2750 rpm for 17.5 min, wash twice with deionized water and absolute ethanol respectively, and dry in vacuum at 57.5 °C for 11 h to obtain the liquid metal for liquid-cooled wire coolant.

[0031] Example 2 Step 1: Preparation of liquid metal mixture: Add 60 g of gallium, 20 g of indium, and 10 g of tin into a vacuum induction furnace, keep it warm at 750 °C for 2 h under argon protection, and then cool it to 15 °C at a cooling rate of 5 °C / min to obtain the liquid metal mixture.

[0032] Step 2. Preparation of liquid metal microdroplets: Mix 100 g of liquid metal mixture with 2000 g of deionized water containing 0.5 wt% of polyvinylpyrrolidone, centrifuge at 8000 rpm for 15 min, and filter through a stainless steel filter mesh with a pore size of 50 μm to obtain liquid metal microdroplets.

[0033] Step 3. Preparation of LDH precursor solution: Under nitrogen protection at 20 °C, dissolve 7.5 g of magnesium nitrate hexahydrate and 3.7 g of aluminum nitrate nonahydrate in 500 g of deionized water, stir and dissolve at 200 rpm for 15 min, adjust the pH to 9.2 with 0.5 M sodium hydroxide solution, and then carry out a water bath at 60 °C for 10 h under nitrogen protection to obtain the LDH precursor solution.

[0034] Step 4. Electrolytic coating: Mix the liquid metal microdroplets and the LDH precursor solution at 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 DC voltage of 2.5 V, a current density of 0.5 A / dm², an electric field period of 10 min, with the forward electric field duration of 6 min and the reverse electric field duration of 4 min in each period, and the electrolysis time is 45 min to obtain liquid metal coated with LDH.

[0035] Step 5. Functionalization treatment: Dissolve octadecylamine in ethanol to prepare a 0.8 mol / L solution, disperse it by ultrasonic wave at a power of 300 W and a frequency of 40 kHz for 30 min, and adjust the pH to 7.5 to obtain the functionalization reagent. Heat the liquid metal coated with LDH to 60 °C at a heating rate of 2 °C / min and keep it warm, adjust the pH to 8.0 at a rate of 0.1 pH unit / min with 0.1 M hydrochloric acid, add the functionalization reagent (the weight ratio of the liquid metal coated with LDH to the functionalization reagent is 1:0.08), stir at 200 rpm at 40 °C for 2 h, centrifuge at 2500 rpm for 15 min, wash 3 times with deionized water and anhydrous ethanol respectively, and dry in vacuum at 55 °C for 10 h to obtain liquid metal for liquid-cooled wire coolant.

[0036] Example 3 Step 1. Preparation of liquid metal mixture: Add 70 g of gallium, 22 g of indium, and 12 g of tin to a vacuum induction furnace, keep it warm at 780 °C for 3 h under argon protection, and then cool it to 30 °C at a cooling rate of 8 °C / min to obtain the liquid metal mixture.

[0037] Step 2. Preparation of liquid metal microdroplets: Mix 100 g of liquid metal mixture with 2000 g of deionized water containing 0.5 wt% of polyvinylpyrrolidone, centrifuge at 12000 rpm for 20 min, and filter through a nylon filter mesh with a pore size of 200 μm to obtain liquid metal microdroplets.

[0038] Step 3. Preparation of LDH precursor solution: Under nitrogen protection at 30°C, 8.0 g of magnesium nitrate hexahydrate and 3.8 g of aluminum nitrate nonahydrate are dissolved in 500 g of deionized water, stirred and dissolved at 300 rpm for 30 min, the pH is adjusted to 9.7 with 0.5 M sodium hydroxide solution, and then under nitrogen protection, it is placed in a water bath at 60°C for 12 h to obtain the LDH precursor solution.

[0039] Step 4. Electrolytic coating: The liquid metal droplets and the LDH precursor solution are mixed at a weight ratio of 1:5. A titanium mesh anode and a stainless steel 316L cathode are used, the electrode spacing is 20 mm, a DC voltage of 2.5 V is applied, the current density is 1.0 A / dm², the electric field period is 10 min, the forward electric field duration is 6 min and the reverse electric field duration is 4 min in each period, and the electrolysis time is 60 min to obtain the liquid metal coated with LDH.

[0040] Step 5. Functionalization treatment: Octadecylamine is dissolved in ethanol to prepare a 0.8 mol / L solution, ultrasonic dispersion is carried out at a power of 300 W and a frequency of 40 kHz for 30 min, and the pH is adjusted to 8.5 to obtain the functionalization reagent. The liquid metal coated with LDH is heated to 70°C at a heating rate of 2°C / min and kept warm, the pH is adjusted to 8.0 at a rate of 0.1 pH unit / min with 0.1 M hydrochloric acid, the functionalization reagent is added (the weight ratio of the liquid metal coated with LDH to the functionalization reagent is 1:0.12), stirred at 200 rpm at 50°C for 3 h, centrifuged at 3000 rpm for 20 min, washed twice with deionized water and anhydrous ethanol respectively, and vacuum dried at 60°C for 12 h to obtain the liquid metal for the liquid cooling line coolant.

[0041] Example 4 Step 1. Preparation of liquid metal mixture: 62 g of gallium, 21 g of indium and 11 g of tin are added to a vacuum induction furnace according to the weight ratio of 62:21:11, kept warm at 760°C for 2.2 h under argon protection, and then cooled to 20°C at a cooling rate of 6°C / min to obtain the liquid metal mixture.

[0042] Step 2. Preparation of liquid metal droplets: 100 g of the liquid metal mixture is mixed with 2000 g of deionized water containing 0.5 wt% of polyvinylpyrrolidone, centrifuged at 9000 rpm for 18 min, and filtered through a stainless steel filter screen with a pore size of 100 μm to obtain the liquid metal droplets.

[0043] Step 3. Preparation of LDH precursor solution: Under nitrogen protection at 22°C, 7.6 g of magnesium nitrate hexahydrate and 3.72 g of aluminum nitrate nonahydrate are dissolved in 500 g of deionized water, stirred and dissolved at 220 rpm for 20 min, the pH is adjusted to 9.3 with 0.5 M sodium hydroxide solution, and then under nitrogen protection, it is placed in a water bath at 60°C for 10.5 h to obtain the LDH precursor solution.

[0044] Step 4, Electrolytic Coating: Mix liquid metal droplets and the LDH precursor solution at 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 period of 10 min. In each period, the forward electric field lasts for 6 min and the reverse electric field lasts for 4 min. The electrolysis time is 48 min to obtain liquid metal coated with LDH.

[0045] Step 5, Functionalization Treatment: Dissolve octadecylamine in ethanol to prepare a 0.8 mol / L solution. Ultrasonically disperse it at a power of 300 W and a frequency of 40 kHz for 30 min, and adjust the pH to 7.8 to obtain a functionalization reagent. Heat the liquid metal coated with LDH at a heating rate of 2 °C / min to 62 °C and keep it warm. Adjust the pH to 8.0 at a rate of 0.1 pH unit / min with 0.1 M hydrochloric acid. Add the functionalization reagent (the weight ratio of the liquid metal coated with LDH to the functionalization reagent is 1:0.09), stir at 200 rpm at 42 °C for 2.2 h, centrifuge at 2600 rpm for 16 min, wash twice with deionized water and anhydrous ethanol respectively, and dry in vacuum at 56 °C for 10.5 h to obtain liquid metal for the liquid cooling line coolant.

[0046] Example 5 Step 1, Preparation of Liquid Metal Mixture: Add 68 g of gallium, 21.5 g of indium, and 11.5 g of tin to a vacuum induction furnace at a weight ratio of 68:21.5:11.5. Keep it warm at 775 °C for 2.8 h under argon protection, and then cool it to 28 °C at a cooling rate of 7.5 °C / min to obtain a liquid metal mixture.

[0047] Step 2, Preparation of Liquid Metal Droplets: Mix 100 g of the liquid metal mixture with 2000 g of deionized water containing 0.5 wt% of polyvinylpyrrolidone, centrifuge at 11000 rpm for 19 min, and filter with a nylon filter with a pore size of 150 μm to obtain liquid metal droplets.

[0048] Step 3, Preparation of LDH Precursor Solution: Under nitrogen protection at 28 °C, dissolve 7.9 g of magnesium nitrate hexahydrate and 3.79 g of aluminum nitrate nonahydrate in 500 g of deionized water, stir and dissolve at 280 rpm for 28 min, adjust the pH to 9.6 with 0.5 M sodium hydroxide solution, and then keep it in a water bath at 60 °C for 11.5 h under nitrogen protection to obtain an LDH precursor solution.

[0049] Step 4. Electrolytic Coating: Mix liquid metal microdroplets and LDH precursor solution at a weight ratio of 1:4.5. Use a titanium mesh anode and a stainless steel 316L cathode with an electrode spacing of 20 mm. Apply a DC voltage of 2.5 V, a current density of 0.9 A / dm², an electric field period of 10 min. In each period, the forward electric field duration is 6 min, the reverse electric field duration is 4 min, and the electrolysis time is 58 min to obtain liquid metal coated with LDH.

[0050] Step 5. Functionalization Treatment: Dissolve octadecylamine in ethanol to prepare a 0.8 mol / L solution, ultrasonic disperse it at a power of 300 W and a frequency of 40 kHz for 30 min, and adjust the pH to 8.2 to obtain a functionalization reagent. Heat the liquid metal coated with LDH at a heating rate of 2 °C / min to 68 °C and keep it warm. Adjust the pH to 8.0 at a rate of 0.1 pH unit / min with 0.1 M hydrochloric acid, add the functionalization reagent (the weight ratio of the liquid metal coated with LDH to the functionalization reagent is 1:0.11), stir at 200 rpm at 48 °C for 2.8 h, centrifuge at 2900 rpm for 19 min, wash 3 times with deionized water and anhydrous ethanol respectively, and dry in vacuum at 59 °C for 11.5 h to obtain liquid metal for liquid cooling line coolant.

[0051] Comparative Example 1: Compared with Example 1, the periodic electric field treatment is missing.

[0052] Step 1. Preparation of Liquid Metal Mixture: Add 65 g of gallium, 21 g of indium, and 11 g of tin into a vacuum induction furnace, keep it warm at 765 °C for 2.5 h 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.

[0053] Step 2. Preparation of Liquid Metal Microdroplets: Mix 100 g of liquid metal mixture with 2000 g of deionized water containing 0.5 wt% of polyvinylpyrrolidone, centrifuge at 10000 rpm for 17.5 min, and filter with a nylon filter with a pore size of 125 μm to obtain liquid metal microdroplets.

[0054] Step 3. Preparation of LDH Precursor Solution: Under nitrogen protection at 25 °C, dissolve 7.75 g of magnesium nitrate hexahydrate and 3.75 g of aluminum nitrate nonahydrate in 500 g of deionized water, stir and dissolve at 250 rpm for 22.5 min, adjust the pH to 9.45 with 0.5 M sodium hydroxide solution, and then keep it in a water bath at 60 °C for 11 h under nitrogen protection to obtain an LDH precursor solution.

[0055] Step 4. DC electrolytic coating: Mix liquid metal droplets and LDH precursor solution at 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 constant DC voltage of 2.5 V, a current density of 0.75 A / dm², and electrolyze for 52.5 min to obtain liquid metal coated with LDH.

[0056] Step 5. Functionalization treatment: Dissolve octadecylamine in ethanol to prepare a 0.8 mol / L solution. Ultrasonically disperse it at a power of 300 W and a frequency of 40 kHz for 30 min, and adjust the pH to 8.0 to obtain a functionalization reagent. Heat the liquid metal coated with LDH at a heating rate of 2 °C / min to 65 °C and keep it warm. Adjust the pH to 8.0 at a rate of 0.1 pH unit / min with 0.1 M hydrochloric acid. Add the functionalization reagent (the weight ratio of the liquid metal coated with LDH to the functionalization reagent is 1:0.10), stir at 45 °C at 200 rpm for 2.5 h, centrifuge at 2750 rpm for 17.5 min, wash twice with deionized water and anhydrous ethanol respectively, and dry in vacuum at 57.5 °C for 11 h to obtain liquid metal for liquid cooling line coolant.

[0057] Comparative Example 2: Compared with Example 1, it lacks the LDH coating layer.

[0058] Step 1. Prepare liquid metal mixture: Add 65 g of gallium, 21 g of indium, and 11 g of tin into a vacuum induction furnace, keep it warm at 765 °C for 2.5 h 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.

[0059] Step 2. Prepare liquid metal droplets: Mix 100 g of liquid metal mixture with 2000 g of deionized water containing 0.5 wt% of polyvinylpyrrolidone, centrifuge at 10000 rpm for 17.5 min, and filter with a nylon filter with a pore size of 125 μm to obtain liquid metal droplets.

[0060] Step 3. Direct functionalization treatment: Dissolve octadecylamine in ethanol to prepare a 0.8 mol / L solution. Ultrasonically disperse it at a power of 300 W and a frequency of 40 kHz for 30 min, and adjust the pH to 8.0 to obtain a functionalization reagent. Heat the liquid metal droplets at a heating rate of 2 °C / min to 65 °C and keep it warm, directly add the functionalization reagent (the weight ratio of the liquid metal coated with LDH to the functionalization reagent is 1:0.10), stir at 45 °C at 200 rpm for 2.5 h, centrifuge at 2750 rpm for 17.5 min, wash twice with deionized water and anhydrous ethanol respectively, and dry in vacuum at 57.5 °C for 11 h to obtain liquid metal for liquid cooling line coolant.

[0061] Comparative Example 3: Compared with Example 1, the ratio of Ga-In-Sn exceeds the scope protected by this application.

[0062] 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 h 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: Prepare liquid metal microdroplets: Mix 100 g of the liquid metal mixture with 2000 g of deionized water containing 0.5 wt% of polyvinylpyrrolidone, centrifuge at 10000 rpm for 17.5 min, and filter through a nylon filter with a pore size of 125 μm to obtain liquid metal microdroplets.

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

[0065] Step 4: Electrochemical coating: Mix the liquid metal microdroplets and the LDH precursor solution at 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 DC voltage of 2.5 V, a current density of 0.75 A / dm², an electric field period of 10 min, in each period, the forward electric field duration is 6 min, the reverse electric field duration is 4 min, and the electrolysis time is 52.5 min to obtain LDH-coated liquid metal.

[0066] Step 5: Functionalization treatment: Dissolve octadecylamine in ethanol to prepare a 0.8 mol / L solution, disperse it by ultrasonic wave at a power of 300 W and a frequency of 40 kHz for 30 min, and adjust the pH to 8.0 to obtain a functionalization reagent. Heat the LDH-coated liquid metal to 65 °C at a heating rate of 2 °C / min and keep it warm, adjust the pH to 8.0 at a rate of 0.1 pH unit / min with 0.1 M hydrochloric acid, add the functionalization reagent (the weight ratio of the LDH-coated liquid metal to the functionalization reagent is 1:0.10), stir at 200 rpm at 45 °C for 2.5 h, centrifuge at 2750 rpm for 17.5 min, wash it twice with deionized water and absolute ethanol respectively, and dry it in vacuum at 57.5 °C for 11 h to obtain liquid metal for liquid-cooled wire coolant.

[0067] Comparative Example 4: Compared with Example 1, the pH value exceeds the scope protected by this application.

[0068] Step 1. Preparation of 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 h under argon protection, and then cool it to 22 °C at a cooling rate of 6.5 °C / min to obtain the liquid metal mixture.

[0069] Step 2. Preparation of liquid metal microdroplets: Mix 100 g of the liquid metal mixture with 2000 g of deionized water containing 0.5 wt% of polyvinylpyrrolidone, centrifuge at 10000 rpm for 17.5 min, and filter through a nylon filter with a pore size of 125 μm to obtain the liquid metal microdroplets.

[0070] Step 3. Preparation of LDH precursor solution: Under nitrogen protection at 25 °C, dissolve 7.75 g of magnesium nitrate hexahydrate and 3.75 g of aluminum nitrate nonahydrate in 500 g of deionized water, stir and dissolve at 250 rpm for 22.5 min, adjust the pH to 10.5 with 0.5 M sodium hydroxide solution, and then keep it in a water bath at 60 °C for 11 h under nitrogen protection to obtain the LDH precursor solution.

[0071] Step 4. Electrolytic coating: Mix the liquid metal microdroplets and the LDH precursor solution at 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 DC voltage of 2.5 V, a current density of 0.75 A / dm², an electric field period of 10 min, in each period, the forward electric field duration is 6 min, the reverse electric field duration is 4 min, and the electrolysis time is 52.5 min to obtain the LDH-coated liquid metal.

[0072] Step 5. Functionalization treatment: Dissolve octadecylamine in ethanol to prepare a 0.8 mol / L solution, disperse it by ultrasonic wave at a power of 300 W and a frequency of 40 kHz for 30 min, and adjust the pH to 8.0 to obtain the functionalization reagent. Heat the LDH-coated liquid metal to 65 °C at a heating rate of 2 °C / min and keep it warm, adjust the pH to 8.0 at a rate of 0.1 pH unit / min with 0.1 M hydrochloric acid, add the functionalization reagent (the weight ratio of the LDH-coated liquid metal to the functionalization reagent is 1:0.10), stir at 200 rpm at 45 °C for 2.5 h, centrifuge at 2750 rpm for 17.5 min, wash it twice with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 57.5 °C for 11 h to obtain the liquid metal for liquid-cooled line coolant.

[0073] Comparative Example 5: Compared with Example 1, the current density exceeds the scope protected by this application.

[0074] Step 1. Preparation of 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 h under argon protection, and then cool it to 22 °C at a cooling rate of 6.5 °C / min to obtain the liquid metal mixture.

[0075] Step 2. Preparation of liquid metal microdroplets: Mix 100 g of the liquid metal mixture with 2000 g of deionized water containing 0.5 wt% of polyvinylpyrrolidone, centrifuge at 10000 rpm for 17.5 min, and filter with a nylon filter with a pore size of 125 μm to obtain the liquid metal microdroplets.

[0076] Step 3. Preparation of LDH precursor solution: Under nitrogen protection at 25 °C, dissolve 7.75 g of magnesium nitrate hexahydrate and 3.75 g of aluminum nitrate nonahydrate in 500 g of deionized water, stir and dissolve at 250 rpm for 22.5 min, adjust the pH to 9.45 with 0.5 M sodium hydroxide solution, and then keep it in a water bath at 60 °C for 11 h under nitrogen protection to obtain the LDH precursor solution.

[0077] Step 4. Electrolytic coating: Mix the liquid metal microdroplets and the LDH precursor solution at 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 DC voltage of 2.5 V, a current density of 1.5 A / dm², an electric field period of 10 min, with a forward electric field duration of 6 min and a reverse electric field duration of 4 min in each period, and an electrolysis time of 52.5 min to obtain the LDH-coated liquid metal.

[0078] Step 5. Functionalization treatment: Dissolve octadecylamine in ethanol to prepare a 0.8 mol / L solution, disperse it by ultrasonic wave at a power of 300 W and a frequency of 40 kHz for 30 min, and adjust the pH to 8.0 to obtain the functionalization reagent. Heat the LDH-coated liquid metal to 65 °C at a heating rate of 2 °C / min and keep it warm, adjust the pH to 8.0 at a rate of 0.1 pH unit / min with 0.1 M hydrochloric acid, add the functionalization reagent (the weight ratio of the LDH-coated liquid metal to the functionalization reagent is 1:0.10), stir at 200 rpm at 45 °C for 2.5 h, centrifuge at 2750 rpm for 17.5 min, wash it twice with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 57.5 °C for 11 h to obtain the liquid metal for liquid-cooled wire coolant.

[0079] Comparative Example 6: Compared with Example 1, the functionalization reagent is missing.

[0080] Step 1. Preparation of 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 h under argon protection, and then cool it to 22 °C at a cooling rate of 6.5 °C / min to obtain the liquid metal mixture.

[0081] Step 2. Preparation of liquid metal microdroplets: Mix 100 g of the liquid metal mixture with 2000 g of deionized water containing 0.5 wt% of polyvinylpyrrolidone, centrifuge at 10000 rpm for 17.5 min, and filter through a nylon filter with a pore size of 125 μm to obtain liquid metal microdroplets.

[0082] Step 3. Preparation of LDH precursor solution: Under nitrogen protection at 25°C, dissolve 7.75 g of magnesium nitrate hexahydrate and 3.75 g of aluminum nitrate nonahydrate in 500 g of deionized water, stir and dissolve at 250 rpm for 22.5 min, adjust the pH to 9.45 with 0.5 M sodium hydroxide solution, and then keep it in a water bath at 60°C for 11 h under nitrogen protection to obtain the LDH precursor solution.

[0083] Step 4. Electrolytic coating: Mix the liquid metal microdroplets and the LDH precursor solution at 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 DC voltage of 2.5 V, a current density of 0.75 A / dm², an electric field period of 10 min, with a forward electric field duration of 6 min and a reverse electric field duration of 4 min in each period, and an electrolysis time of 52.5 min to obtain liquid metal coated with LDH.

[0084] Step 5. Direct treatment: Heat the liquid metal coated with LDH to 65°C at a heating rate of 2°C / min and keep it warm, adjust the pH to 8.0 at a rate of 0.1 pH unit / min with 0.1 M hydrochloric acid, stir at 200 rpm at 45°C for 2.5 h, centrifuge at 2750 rpm for 17.5 min, wash twice with deionized water and anhydrous ethanol respectively, and dry in vacuum at 57.5°C for 11 h to obtain liquid metal for liquid-cooled wire coolant.

[0085] Comparative Example 7: Compared with Example 1, the heat preservation temperature exceeds the scope protected by this application.

[0086] Step 1. Preparation of liquid metal mixture: Add 65 g of gallium, 21 g of indium, and 11 g of tin into a vacuum induction furnace, keep it warm at 900°C for 2.5 h under argon protection, and then cool it to 22°C at a cooling rate of 6.5°C / min to obtain the liquid metal mixture.

[0087] Step 2. Preparation of liquid metal microdroplets: Mix 100 g of the liquid metal mixture with 2000 g of deionized water containing 0.5 wt% of polyvinylpyrrolidone, centrifuge at 10000 rpm for 17.5 min, and filter through a nylon filter with a pore size of 125 μm to obtain liquid metal microdroplets.

[0088] Step 3. Preparation of LDH precursor solution: Under nitrogen protection at 25 °C, dissolve 7.75 g of magnesium nitrate hexahydrate and 3.75 g of aluminum nitrate nonahydrate in 500 g of deionized water, stir and dissolve at 250 rpm for 22.5 min, adjust the pH to 9.45 with 0.5 M sodium hydroxide solution, and then carry out a water bath at 60 °C for 11 h under nitrogen protection to obtain the LDH precursor solution.

[0089] Step 4. Electrolytic coating: Mix liquid metal microdroplets and the LDH precursor solution at 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 DC voltage of 2.5 V, a current density of 0.75 A / dm², an electric field period of 10 min. In each period, the forward electric field duration is 6 min and the reverse electric field duration is 4 min. The electrolysis time is 52.5 min to obtain LDH-coated liquid metal.

[0090] Step 5. Functionalization treatment: Dissolve octadecylamine in ethanol to prepare a 0.8 mol / L solution, ultrasonically disperse at a power of 300 W and a frequency of 40 kHz for 30 min, and adjust the pH to 8.0 to obtain a functionalization reagent. Heat the LDH-coated liquid metal at a heating rate of 2 °C / min to 65 °C and keep it warm. Adjust the pH to 8.0 at a rate of 0.1 pH unit / min with 0.1 M hydrochloric acid, add the functionalization reagent (the weight ratio of the LDH-coated liquid metal to the functionalization reagent is 1:0.10), stir at 200 rpm at 45 °C for 2.5 h, centrifuge at 2750 rpm for 17.5 min, wash twice with deionized water and anhydrous ethanol respectively, and dry in vacuum at 57.5 °C for 11 h to obtain the liquid metal for the liquid-cooled wire coolant.

[0091] Comparative Example 8: Compared with Example 1, the ratio of the functionalization reagent exceeds the scope protected by this application.

[0092] Step 1. Preparation of liquid metal mixture: Add 65 g of gallium, 21 g of indium, and 11 g of tin to a vacuum induction furnace, keep warm at 765 °C for 2.5 h under argon protection, and then cool to 22 °C at a cooling rate of 6.5 °C / min to obtain the liquid metal mixture.

[0093] Step 2. Preparation of liquid metal microdroplets: Mix 100 g of the liquid metal mixture with 2000 g of deionized water containing 0.5 wt% of polyvinylpyrrolidone, centrifuge at 10000 rpm for 17.5 min, and filter with a nylon filter with a pore size of 125 μm to obtain liquid metal microdroplets.

[0094] Step 3. Preparation of LDH precursor solution: Under nitrogen protection at 25°C, dissolve 7.75 g of magnesium nitrate hexahydrate and 3.75 g of aluminum nitrate nonahydrate in 500 g of deionized water, stir and dissolve at 250 rpm for 22.5 min, adjust the pH to 9.45 with 0.5 M sodium hydroxide solution, and then carry out a water bath at 60°C for 11 h under nitrogen protection to obtain the LDH precursor solution.

[0095] Step 4. Electrolytic coating: Mix liquid metal microdroplets and the LDH precursor solution at 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 DC voltage of 2.5 V, a current density of 0.75 A / dm², and an electric field period of 10 min. In each period, the forward electric field duration is 6 min and the reverse electric field duration is 4 min. The electrolysis time is 52.5 min to obtain LDH-coated liquid metal.

[0096] Step 5. Functionalization treatment: Dissolve octadecylamine in ethanol to prepare a 0.8 mol / L solution, ultrasonically disperse it at a power of 300 W and a frequency of 40 kHz for 30 min, and adjust the pH to 8.0 to obtain the functionalization reagent. Heat the LDH-coated liquid metal at a heating rate of 2°C / min to 65°C and keep it warm. Adjust the pH to 8.0 at a rate of 0.1 pH unit / min with 0.1 M hydrochloric acid, add the functionalization reagent (the weight ratio of the LDH-coated liquid metal to the functionalization reagent is 1:0.2), stir at 200 rpm at 45°C for 2.5 h, centrifuge at 2750 rpm for 17.5 min, wash twice with deionized water and anhydrous ethanol respectively, and dry in vacuum at 57.5°C for 11 h to obtain the liquid metal for the liquid cooling line coolant.

[0097] Performance testing 1. Thermal conductivity test Testing equipment: Laser flash method thermal conductivity tester (LFA457) Testing step 1: Load the liquid metal sample into a graphite crucible with a diameter of 12.7 mm and a thickness of 2 - 3 mm to ensure that the sample thickness is uniform.

[0098] Testing step 2: Spray a graphite coating with a thickness of about 10 - 20 μm on the sample surface to improve the surface absorptivity and emissivity.

[0099] Testing step 3: Place the sample in the test furnace, introduce an argon protective atmosphere with a flow rate of 50 ml / min to eliminate the influence of oxygen.

[0100] Testing 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.

[0101] Test Step Five: Conduct tests under the condition of constant temperature at 25°C. Each sample is tested 5 times with a 10-minute interval between tests.

[0102] Test Step Six: Fit the temperature rise curve using the Cape-Lehman model, calculate the thermal diffusivity, and calculate the thermal conductivity by combining the specific heat capacity and density.

[0103] 2. Conductivity Test Test Equipment: Precision LCR tester with a four-probe test fixture Test Step One: Inject the liquid metal into a PTFE test cell with a length of 50 mm, a width of 5 mm, and a height of 2 mm.

[0104] Test Step Two: Insert four platinum wire electrodes with a diameter of 0.5 mm. The distance between the two outer electrodes is 40 mm, and the distance between the two inner electrodes is 20 mm.

[0105] Test Step Three: Set the test current to 100 mA and the frequency to 1 kHz to avoid the influence of electrochemical reactions.

[0106] Test Step Four: Start the test after stabilizing for 10 minutes in a constant temperature environment at 25°C.

[0107] Test Step Five: Continuously test for 60 seconds, record the resistance value every 5 seconds, and each sample is tested 3 times.

[0108] Test Step Six: Calculate the conductivity according to the geometric dimensions and Ohm's law: σ = L / (R×A), where L is the electrode distance and A is the cross-sectional area.

[0109] 3. Long-term Stability Test Test Step One: Seal 50 ml of the sample in glass ampoules respectively and fill with argon for protection.

[0110] Test Step Two: Place the samples in constant temperature incubators at -40°C, 25°C, and 80°C for 90 days respectively.

[0111] Test Step Three: Take out the samples every 15 days, and test the thermal conductivity and conductivity after restoring to room temperature.

[0112] Test Step Four: Observe the appearance change of the samples and record whether there is phase separation, oxidation, or precipitation.

[0113] Test Step Five: Calculate the performance retention rate: η = (Pt / P0)×100%, where P0 is the initial performance and Pt is the performance after time t.

[0114] 4. Viscosity and Rheology Test Test Equipment: Rotational rheometer (Anton Paar MCR302) Test Step 1: Adopt a parallel - plate geometry configuration with a plate spacing of 1 mm and a test temperature of 25 °C.

[0115] Test Step 2: Pre - shear treatment: Shear at a shear rate of 100 s⁻¹ for 60 seconds and then let it stand for 120 seconds to eliminate the shear history.

[0116] Test Step 3: Conduct a steady - state shear test with the shear rate increasing from 0.1 s⁻¹ -1 to 1000 s⁻¹ -1 , and test for 30 seconds at each point.

[0117] Test Step 4: Conduct a frequency - sweep test with a frequency range of 0.1 - 100 Hz and a strain amplitude of 1%.

[0118] Test Step 5: Test the temperature dependence with a temperature range of 15 - 85 °C and a heating rate of 2 °C / min.

[0119] 5. Thermal cycling stability test Test Step 1: Place the sample in a sealed stainless - steel test tube filled with argon for protection.

[0120] Test Step 2: Set the thermal cycling program: Heat from room temperature to 80 °C and hold for 1 hour, then cool to - 20 °C and hold for 1 hour for one cycle.

[0121] Test Step 3: Continuously conduct 500 thermal cycles, and take samples for testing every 50 cycles during this period.

[0122] Test Step 4: Test the changes in thermal conductivity, electrical conductivity, and viscosity at each cycle node.

[0123] Test Step 5: Analyze the effect of thermal cycling on the microstructure and evaluate the long - term use reliability.

[0124] 6. Material compatibility test Test Step 1: Select common cooling pipe materials: pure copper (T2), 6061 aluminum alloy, 304 stainless steel, and make test pieces with dimensions of 30 x 10 x 2 mm.

[0125] Test Step 2: Polish the surface of the test pieces to Ra not greater than 0.4 μm, and clean and degrease them successively with anhydrous ethanol and acetone.

[0126] Test Step 3: Immerse the test pieces completely in the liquid metal and conduct an accelerated corrosion test in a 60 °C constant - temperature oven.

[0127] Test Step 4: Take out the test pieces after 7 days, 30 days, and 90 days respectively, and ultrasonically clean them to remove the residual liquid metal.

[0128] Test data table Table 1. Thermal conductivity test results (W / m·K, 25 °C)

[0129] Table 2. Test Results of Electrical Conductivity (×10 6 S / m, 25 °C)

[0130] Table 3. Test Results of 90-day Long-term Stability (Performance Retention Rate %)

[0131] Table 4. Test Results of Viscosity (mPa·s, 25 °C, Shear Rate 100 s -1 )

[0132] Table 5. Performance Change Rate after 500 Thermal Cycles (%)

[0133] Table 6. Test Results of 90-day Material Compatibility (Corrosion Rate mg / cm²·d, 60 °C)

[0134] Data Analysis 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) with 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 those of Comparative Examples 1-8, respectively. The effect of the periodic electric field treatment is reflected in the difference between Comparative Example 1 and direct current electrolysis. The thermal conductivity of Example 1 is 17.2% higher than that of 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 without LDH coating decreases most significantly, indicating that the LDH layer not only provides a protective effect, but its layered structure can also improve the phonon transmission path and significantly enhance the thermal conduction performance. The standard deviations of the examples are all less than 0.5, 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.

[0135] As can be seen from Table 2, the embodiments of the present invention show obvious advantages in terms of electrical conductivity. The highest electrical conductivity of Example 3 is 3.72×10 6 S / m (corresponding resistivity 26.9 μΩ·cm), which is higher than that of Comparative Example 2 (2.58×10 6S / m, with a resistivity 44.2% higher than that of 38.8 μΩ·cm). The conductivity of Example 1 is 3.64×10 6 S / m, which is increased by 16.7%, 41.1%, 8.7%, 26.0%, 11.7%, 34.3%, 14.5%, and 23.8% respectively compared with each comparative example. From the perspective of resistivity, the 27.5 μΩ·cm of Example 1 is close to the theoretical value of pure Ga-In-Sn alloy (about 25 - 28 μΩ·cm), while the 38.8 μΩ·cm of Comparative Example 2 indicates a significant increase in interface resistance. The LDH coating layer 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 layer and the liquid metal interface, reducing the contact resistance. The conductivity of Comparative Example 4 with too high pH value and Comparative Example 6 without functionalizing reagent decreases significantly, indicating the importance of a suitable chemical environment for maintaining excellent electrical properties.

[0136] As can be seen from Table 3, Example 1 of the present invention has significant advantages in terms of long-term stability. In the harshest environment of 80 °C, the retention rates of thermal conductivity and conductivity of Example 1 still reach 94.2% and 93.1% respectively, while those of Comparative Example 1 are only 84.9% and 82.6%, and those of Comparative Example 2 even drop to 74.6% and 71.9%. Under the low-temperature condition of -40 °C, the performance retention rates of Example 1 are 96.8% and 95.4%, significantly better than those of Comparative Example 1, which are 88.5% and 86.1%, and those of Comparative Example 2, which are 79.3% and 76.8%. The stability test at room temperature of 25 °C shows that Example 1 performs the best, with the performance retention rates reaching 98.9% and 98.2% after 90 days. This excellent stability is mainly attributed to the protective effect of the LDH coating layer. Its interlayer anions (CO3 2- 、OH - ) can inhibit the oxidation of liquid metal, and the dense coating layer structure formed by the periodic electric field treatment further enhances the environmental adaptability. Due to the lack of a protective layer, Comparative Example 2 undergoes obvious phase separation and surface oxidation during the temperature change process, resulting in rapid performance decay.

[0137] As can be seen from Table 4, the viscosity and rheological properties of the embodiments of the present invention are significantly superior to those of the comparative examples. The viscosity of Example 3 is the lowest at 1.85 mPa·s, which is 55.4% lower than that of Comparative Example 2 with the highest viscosity (4.15 mPa·s). The viscosity of Example 1 is 1.92 mPa·s, which is reduced by 29.7%, 53.7%, 15.8%, 36.4%, 25.6%, 48.9%, 23.5%, and 41.6% respectively compared with Comparative Examples 1-8. The analysis of the flow index n value shows that the n value of the embodiments is close to 1 (0.97-0.99), showing near-Newtonian fluid characteristics, while the n value of the comparative examples drops to 0.89-0.96, showing certain shear thinning behavior. The lubricating effect of the LDH coating layer and the surface modification effect of the functionalizing reagent synergistically reduce the inter-particle friction, and the uniform coating formed by the periodic electric field treatment avoids the increase in viscosity caused by local agglomeration. The viscosity of Comparative Example 2 without the LDH coating surges to 4.15 mPa·s, indicating the existence of strong van der Waals forces and surface tension between the bare liquid metal particles. The appropriate viscosity is beneficial to the circulating flow in the cooling system, reducing the pumping power consumption and improving the heat transfer efficiency.

[0138] As can be seen from Table 5, the 500-cycle thermal cycle test further verifies the long-term reliability advantage of the present invention. After Example 1 undergoes 500 thermal cycles from -20°C to 80°C, the thermal conductivity and electrical conductivity only decrease by 2.1% and 1.8% respectively, and the viscosity increases by 1.6%, with extremely small performance changes. In contrast, the performance decline of Comparative Example 1 reaches 5.9% - 6.4%, and the performance attenuation of Comparative Example 2 without protection is the most serious, with the thermal conductivity decreasing by 12.3%, the electrical conductivity decreasing by 11.7%, and the viscosity increasing by 9.3%. The repeated thermal expansion and contraction during the thermal cycle will generate stress at the material interface, leading to the initiation and propagation of microcracks. The LDH coating layer has a certain flexibility and self-healing ability, which can relieve the thermal stress and inhibit the crack propagation, while the functionalizing reagent further enhances the interfacial bonding strength. Although Comparative Example 6 has the LDH coating but lacks the functionalization treatment, its thermal cycle performance is between that of the embodiment and the comparative example with serious defects, proving the important role of the functionalization treatment in improving the thermal cycle stability.

[0139] As can be seen from Table 6, Example 1 of the present invention has extremely low corrosivity to common cooling pipe materials, demonstrating excellent material compatibility. The corrosion rate of 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 of 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 each comparative example. According to industrial standards, a corrosion rate lower than 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 the direct contact between liquid metal and pipe materials, and the organic protective film formed by functional reagents further reduces the driving force of electrochemical corrosion. Comparative Example 2 without a protective layer has the strongest corrosivity. In particular, the corrosion rate of copper materials is as high as 0.0348 mg / cm²·d, which will cause rapid damage to the pipeline system and coolant pollution. Obviously, the technical solution of this application significantly improves the application range and engineering application value of liquid metal coolants.

[0140] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can 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 application shall still fall within the scope covered by the patent of the present invention.

Claims

1. A liquid metal for use as a coolant in a liquid cooling line, characterized in that it is Prepared through the following steps: Step 1: Mix the liquid metal mixture with deionized water containing polyvinylpyrrolidone, centrifuge, and filter to obtain liquid metal microdroplets; Step 2: Under nitrogen protection at 20 - 30 °C, dissolve magnesium nitrate hexahydrate and aluminum nitrate nonahydrate in deionized water, stir to dissolve, adjust the pH to 9.2 - 9.7 with 0.5 M sodium hydroxide solution, and then carry out a water bath at 60 °C for 10 - 12 h under nitrogen protection to obtain the LDH precursor solution; Step 3: Mix the liquid metal microdroplets with the LDH precursor solution, apply a periodic electric field for electrolysis to obtain liquid metal coated with LDH; Step 4: Heat and keep the liquid metal coated with LDH warm, adjust the pH to 8.0 with 0.1 M hydrochloric acid, add the functionalization reagent, stir, centrifuge, wash 2 - 3 times with deionized water or absolute ethanol, and dry under vacuum to obtain the liquid metal for the liquid cooling line coolant.

2. The liquid metal for the liquid coolant of the liquid cooling line according to claim 1, wherein The liquid metal mixture is prepared through the following steps: Add gallium, indium, and tin to a vacuum induction furnace, keep warm under argon protection, and then cool to 15 - 30 °C to obtain the liquid metal mixture.

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

4. The liquid metal for the liquid coolant of the liquid-cooled wire according to claim 1, wherein The mass fraction of polyvinylpyrrolidone in the deionized water containing polyvinylpyrrolidone is 0.5 wt%.

5. The liquid metal for use as a coolant in a liquid-cooled wire according to claim 1, characterized in that, In Step 1, the centrifugation rate is 8000 - 12000 rpm, the centrifugation time is 15 - 20 min, and the filtration is carried out using a nylon filter or a stainless steel filter with a pore size of 50 - 200 μm.

6. The liquid metal for the liquid coolant of the liquid cooling line according to claim 1, characterized in that, 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 for stirring and dissolving is 200 - 300 rpm, and the stirring time is 15 - 30 min.

7. The liquid metal for the liquid coolant of the liquid-cooled wire according to claim 1, characterized in that, In Step 3, the weight ratio of the liquid metal microdroplets to the LDH precursor solution is 1:3 - 5.

8. The liquid metal for the liquid coolant of the liquid-cooled wire according to claim 1, characterized in that, The parameters of the periodic electric field are as follows: Use a titanium mesh anode and a stainless steel 316L cathode, the electrode spacing is 20 mm, apply a 2.5 V DC voltage, the current density is 0.5 - 1.0 A / dm², the electric field period is 10 min, the duration of the positive electric field in each period is 6 min, the duration of the negative electric field is 4 min, and the electrolysis time is 45 - 60 min.

9. The liquid metal for the liquid coolant of the liquid-cooled wire according to claim 1, characterized in that, The functionalization reagent is prepared by dissolving octadecylamine in ethanol to form a 0.8 mol / L solution, ultrasonic dispersing for 30 min at a power of 300 W and a frequency of 40 kHz, and adjusting the pH to 7.5 - 8.

5.

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

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