A modified gallium-based liquid metal paste and its preparation method

Abstract

The present invention discloses a modified gallium-based liquid metal paste, which comprises, by mass percentage, 50%-98% gallium-based liquid metal and 2%-50% modified nickel powder. The present invention provides a simple gallium-based liquid metal paste with uniformly dispersed fillers. By modifying the nickel powder and optimizing the preparation method, the modified nickel powder can be well dispersed in the liquid metal, and the modified liquid metal has good adhesion to the substrate surface.

Description

Technical Field

[0001] The present invention relates to the field of advanced metal materials, and more particularly to a modified gallium-based liquid metal paste and a preparation method thereof. Background Art

[0002] Liquid metals are metals that are liquid at room temperature. They have attracted considerable attention due to their combined properties of both liquids and metals. Common liquid metals include mercury, gallium, cesium, and francium. However, mercury is volatile and highly toxic; cesium is extremely reactive, easily oxidized, and can spontaneously combust, resulting in poor stability; and francium is radioactive. Therefore, gallium and gallium-based liquid metals, which are non-toxic and harmless, have attracted the most extensive research.

[0003] However, the excessive fluidity of pure gallium-based liquid metal poses a risk of leakage during use, affecting the stability and reliability of electronic devices. Furthermore, gallium-based liquid metal has ultra-high surface tension and poor wettability. CN114621809A discloses a high-performance, multi-scale lubricating gallium-based liquid metal lubricant and its preparation method. The specific formula comprises an alloyed modified liquid metal composed of 95-99wt% GaInSn and 1-5wt% Bi, followed by a gallium-based liquid metal lubricant composed of 98.5-99.7wt% of the alloyed modified liquid metal and 0.3-1.5wt% of a composite powder of boron nitride and tungsten disulfide. The prepared gallium-based liquid metal lubricant has a melting point below room temperature and excellent lubrication properties, showing promising application prospects. Although adding fillers to gallium-based liquid metal can solve the technical problem that pure gallium-based liquid metal has ultra-high surface tension, poor wettability, and difficulty in adhering to the substrate surface, the high surface tension of gallium-based liquid metal makes it difficult for the filler to mix evenly with the liquid metal and difficult to disperse evenly in the liquid metal substrate.

[0004] Therefore, it becomes an important task to develop a simple gallium-based liquid metal paste with uniformly dispersed fillers. Summary of the Invention

[0005] In order to solve the above problems, the present invention discloses a modified gallium-based liquid metal paste, which comprises 50%-98% gallium-based liquid metal and 2%-50% modified nickel powder in percentage by mass.

[0006] As a preferred technical solution, the raw materials for preparing the gallium-based liquid metal are selected from one or more of gallium, indium, tin, and bismuth.

[0007] Preferably, the raw materials for preparing the gallium-based liquid metal are gallium, indium and tin.

[0008] More preferably, the mass ratio of gallium, indium and tin is (65-70):(20-23):(8-12).

[0009] As a preferred technical solution, the method for preparing the gallium-based liquid metal comprises the following steps:

[0010] (1) placing metallic gallium in a sealed flask according to the ratio, placing it in a water bath, and heating it at a constant temperature to obtain liquid gallium;

[0011] (2) Indium and tin are added to the liquid gallium obtained in step (1) according to the ratio, and the mixture is placed in a water bath and stirred at a constant temperature under anaerobic conditions until the indium and tin are melted into liquid form. After uniform mixing, gallium-based liquid metal is obtained.

[0012] As a preferred technical solution, in step (1), the water bath temperature is 50-60° C. and the heating time is 20-30 minutes.

[0013] As a preferred technical solution, in step (2), the water bath temperature is 50-60° C. and the stirring is performed for 2-4 hours.

[0014] As a preferred technical solution, the raw materials for preparing the modified nickel powder include: 8-12g nickel powder, 0.8-1.5g dopamine, 80-120mL silver nitrate, 0.6-0.8g dimethylamine borane and 0.6-0.7g copper chloride, 0.4-0.6g trishydroxymethylaminomethane (Tris), 1.5-1.8g EDTA·2Na, and 0.6-0.7g boric acid.

[0015] Preferably, the nickel powder is spherical nickel powder purchased from Guangzhou Metal Metallurgy Co., Ltd., with an average particle size of 200 nm.

[0016] As a preferred technical solution, the concentration of the silver nitrate is 30-60 mM, preferably 50 mM.

[0017] As a preferred technical solution, the copper chloride is CuCl2·2H2O, and the concentration is 40-70mM, preferably 50mM.

[0018] As a preferred technical solution, the concentration of the EDTA·2Na is 30-60 mM, preferably 50 mM.

[0019] As a preferred technical solution, the concentration of the boric acid is 0.05-0.2M, preferably 0.1M.

[0020] As a preferred technical solution, the concentration of dimethylamine borane is 0.05-0.2M, preferably 0.1M.

[0021] As a preferred technical solution, the preparation method of the modified nickel powder comprises the following steps:

[0022] (1) Prepare a Tris-HCl buffer solution with a pH of 8.5;

[0023] (2) adding dopamine to the solution obtained in step (1), adding nickel powder, blowing air into the solution, and reacting for a period of time;

[0024] (3) filtering the solution obtained in step (2), washing the obtained particles with clean water 5-6 times, and then drying them in a vacuum oven;

[0025] (4) adding the particles obtained in step (3) to a silver nitrate solution and stirring in a water bath for 30-90 minutes;

[0026] (5) filtering the solution obtained in step (4), washing the obtained particles with clean water 5-6 times, and then drying them in a vacuum oven;

[0027] (6) Prepare a solution of CuCl2·2H2O, EDTA·2Na, boric acid, and dimethylamine borane, and adjust the solution to neutral;

[0028] (7) adding the precipitate obtained in step (5) to the solution obtained in step (6) and reacting in a water bath for 2-4 hours;

[0029] (8) The solution obtained in step (7) is filtered, and the obtained particles are washed with ethanol and water for 5-6 times respectively, and then dried in a vacuum oven.

[0030] A second aspect of the present invention provides a method for preparing the modified gallium-based liquid metal paste, comprising the following steps:

[0031] S1: taking out a certain amount of gallium-based liquid metal and adding modified nickel powder into it;

[0032] S2: Stir the mixture obtained in S1 in air using an electric stirrer;

[0033] S3: Use a vacuum mixer to stir the mixture obtained in S2 under vacuum conditions until it is evenly mixed.

[0034] As a preferred technical solution, the stirring speed in step S2 is 400-1200 r / min, and the stirring time is 15-30 min.

[0035] As a preferred technical solution, the stirring speed in step S3 is 200-2000 r / min, and the stirring time is 15-30 min.

[0036] The modified nickel powder and liquid metal can be evenly dispersed in the liquid metal substrate within the above-mentioned ratio range, thereby ensuring improved wettability. The reason is: during the entire process, Ni powder is pumped into air under a weakly alkaline environment, and dopamine is deposited on Ni to form polydopamine. Polydopamine reduces the Ag in silver nitrate to form active sites. Polydopamine and dimethylamine borane reduce copper chloride to Cu on the active sites, forming a Cu core-Ni shell structure. Since the surface tension of liquid metal is very large, if this layer of copper core is not added, nickel powder will be difficult to disperse in liquid metal. However, since Cu and liquid metal can react and there is a metallic bond between the two, adding a copper shell can make the entire filler well dispersed in the liquid metal.

[0037] Secondly, nickel is the core, and nickel is magnetic. Therefore, when the liquid metal with the core-shell structure filler (hereinafter referred to as modified liquid metal) is applied to other fields, it can achieve self-repair under a magnetic field. For example, if the modified liquid metal is used as a wire in a flexible circuit, if the wire is broken, then just apply a magnetic field and move along the broken part, and then the nickel will move with the magnetic field, thereby driving the entire modified liquid metal to move, so that the circuit can be self-repaired. Finally, the entire modified liquid metal is in a paste-like state, and its surface is no longer a pure liquid metal with high surface tension, but some substances with lower surface tension such as gallium oxide, so it can improve the adhesion to the substrate.

[0038] Beneficial effects

[0039] 1. Control the mass ratio of gallium, indium and tin in the raw materials for preparing gallium-based liquid metal, and the preparation method, so that the melting point of the obtained gallium-based liquid metal is 8-12°C.

[0040] 2. The modified nickel powder and liquid metal can be evenly dispersed in the liquid metal substrate within the above ratio range, thereby ensuring improved wettability.

[0041] 3. Polydopamine and dimethylamine borane reduce copper chloride to Cu at the active site, forming a Cu core-Ni shell structure. Cu can react with liquid metal, and there is a metallic bond between the two. Therefore, adding a copper shell can make the entire filler well dispersed in the liquid metal.

[0042] 4. Nickel is the core and has magnetism. Therefore, when liquid metal with the core-shell structure filler (hereinafter referred to as modified liquid metal) is applied in other fields, it can achieve self-repair under a magnetic field. DETAILED DESCRIPTION

[0043] Example 1

[0044] This embodiment 1 discloses a modified gallium-based liquid metal paste, which comprises 78% gallium-based liquid metal and 22% modified nickel powder by mass percentage.

[0045] The gallium-based liquid metal comprises gallium, indium and tin, with a mass ratio of 68:22:10.

[0046] The preparation method of the gallium-based liquid metal is:

[0047] (1) Gallium metal was placed in a sealed flask according to the ratio, and placed in a 55°C water bath. At a constant temperature, it was heated for 25 minutes to obtain liquid gallium;

[0048] (2) Indium and tin are added to the liquid gallium obtained in step (1) according to the ratio, and placed in a 55°C water bath, and stirred at a constant temperature for 3 hours under anaerobic conditions until the indium and tin are melted into liquid form. After mixing evenly, gallium-based liquid metal is obtained.

[0049] The raw materials for preparing the modified nickel powder are: 10g nickel powder, 1g dopamine, 100mL silver nitrate, 0.70716g dimethylamine borane, 0.67225g copper chloride, 0.5g trishydroxymethylaminomethane (Tris), 1.68103g EDTA·2Na, and 0.6183g boric acid.

[0050] The nickel powder is spherical nickel powder purchased from Guangzhou Metal Metallurgy Co., Ltd., with an average particle size of 200 nm.

[0051] The concentration of the silver nitrate was 50 mM.

[0052] The copper chloride is CuCl2·2H2O, and its concentration is 50 mM.

[0053] The concentration of the EDTA·2Na is 50 mM.

[0054] The concentration of the boric acid is 0.1M.

[0055] The concentration of the dimethylamine borane is 0.1M.

[0056] The preparation method of the modified nickel powder is:

[0057] (1) Prepare a Tris-HCl buffer solution with a pH of 8.5;

[0058] (2) adding dopamine to the solution obtained in step (1), adding nickel powder, blowing air into it, and reacting for a period of time;

[0059] (3) filtering the solution obtained in step (2), washing the obtained particles with clean water five times, and then drying them in a vacuum oven;

[0060] (4) adding the particles obtained in step (3) to a silver nitrate solution and stirring in a water bath for 60 min;

[0061] (5) filtering the solution obtained in step (4), washing the obtained particles with clean water five times, and then drying them in a vacuum oven;

[0062] (6) Prepare a solution of CuCl2·2H2O, EDTA·2Na, boric acid, and dimethylamine borane, and adjust the solution to neutral;

[0063] (7) adding the precipitate obtained in step (5) to the solution obtained in step (6) and reacting in a water bath for 3 h;

[0064] (8) The solution obtained in step (7) was filtered, and the obtained particles were washed with ethanol and water for 6 times respectively, and then dried in a vacuum oven.

[0065] On the other hand, this embodiment 1 provides a method for preparing the modified gallium-based liquid metal paste, which comprises the following steps:

[0066] S1: taking out a certain amount of gallium-based liquid metal and adding modified nickel powder into it;

[0067] S2: Use an electric stirrer to stir the mixture obtained in S1 in air at a stirring speed of 800 r / min for 20 min;

[0068] S3: Use a vacuum mixer to stir the mixture obtained in S2 under vacuum conditions at a stirring speed of 1400 r / min for 25 min until the mixture is evenly mixed.

[0069] Example 2

[0070] The difference between this embodiment and embodiment 1 is that: a modified gallium-based liquid metal paste comprises, by mass percentage, 50% gallium-based liquid metal and 50% modified nickel powder;

[0071] The gallium-based liquid metal comprises gallium, indium and tin, with a mass ratio of 65:23:12.

[0072] Example 3

[0073] The difference between this embodiment and embodiment 1 is that: a modified gallium-based liquid metal paste comprises, by mass percentage, 98% gallium-based liquid metal and 2% modified nickel powder;

[0074] The gallium-based liquid metal comprises gallium, indium and tin in a mass ratio of 70:20:10.

[0075] Example 4

[0076] The difference between this embodiment and embodiment 1 is that the modified gallium-based liquid metal paste contains 78% gallium-based liquid metal and 22% nickel powder by mass.

[0077] The nickel powder is spherical nickel powder purchased from Guangzhou Metal Metallurgy Co., Ltd., with an average particle size of 200 nm.

[0078] Performance Testing

[0079] 1. DSC test: The gallium-based liquid metals prepared in Examples 1-3 were measured using a Mettler DSC3 device and a 40 μl standard alumina ceramic crucible to test the initial melting temperature.

[0080] 2. Dispersibility: observe whether the modified gallium-based liquid metal paste is well dispersed.

[0081] 3. Self-healing capability: The modified gallium-based liquid metal paste formed in Examples 1-4 was applied to a flexible substrate to form a flexible circuit. After artificially cutting the circuit, a magnet was placed under the broken portion. The magnet was moved to connect the broken portion through the action of the magnetic field, thus re-forming a conductive path. The resistance change during the above process was tested.

[0082]

Claims

1. A modified gallium-based liquid metal paste, characterized in that: The invention comprises 50%-98% gallium-based liquid metal and 2%-50% modified nickel powder by mass percentage; the raw materials for preparing the gallium-based liquid metal are gallium, indium and tin; the mass ratio of gallium, indium and tin is (65-70): (20-23): (8-12); the preparation method of the gallium-based liquid metal comprises the following steps: (1) placing metallic gallium in a sealed flask according to the ratio, placing it in a water bath, and heating it at a constant temperature to obtain liquid gallium; (2) adding indium and tin to the liquid gallium obtained in step (1) according to the ratio, placing the mixture in a water bath, and stirring the mixture at a constant temperature under anaerobic conditions until the indium and tin melt into liquid form and the mixture is evenly mixed to obtain a gallium-based liquid metal; The raw materials for preparing the modified nickel powder include: spherical nickel powder, dopamine, silver nitrate, dimethylamine borane and copper chloride, tris(hydroxymethyl)aminomethane, EDTA·2Na, and boric acid; the preparation method of the modified nickel powder includes the following steps: (1) Prepare a Tris-HCl buffer solution with a pH of 8.5; (2) adding dopamine to the solution obtained in step (1), adding nickel powder, blowing air into the solution, and reacting for a period of time; (3) filtering the solution obtained in step (2), washing the obtained particles with clean water 5-6 times, and then drying them in a vacuum oven; (4) adding the particles obtained in step (3) to a silver nitrate solution and stirring in a water bath for 30-90 minutes; (5) filtering the solution obtained in step (4), washing the obtained particles with clean water 5-6 times, and then drying them in a vacuum oven; (6) Prepare a solution of CuCl2·2H2O, EDTA·2Na, boric acid, and dimethylamine borane, and adjust the solution to neutral; (7) adding the precipitate obtained in step (5) to the solution obtained in step (6) and reacting in a water bath for 2-4 hours; (8) The solution obtained in step (7) is filtered, and the obtained particles are washed with ethanol and water for 5-6 times respectively, and then dried in a vacuum oven.

2. The gallium-based liquid metal paste according to claim 1, characterized in that: In step (1), the water bath temperature is 50-60° C. and the heating time is 20-30 minutes.

3. A method for preparing a gallium-based liquid metal paste according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1: taking out a certain amount of gallium-based liquid metal and adding modified nickel powder into it; S2: Stir the mixture obtained in S1 in air using an electric stirrer; S3: Use a vacuum mixer to stir the mixture obtained in S2 under vacuum conditions until it is evenly mixed.

4. The method for preparing gallium-based liquid metal paste according to claim 3, characterized in that: The stirring speed in step S2 is 400-1200 r / min.

5. The method for preparing gallium-based liquid metal paste according to claim 4, characterized in that: The stirring speed in step S3 is 200-2000 r / min.

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