Liquid metal clad wire and preparation method thereof

Abstract

The present invention belongs to the technical field of metal materials, and specifically relates to a liquid metal clad wire and a preparation method thereof, wherein the liquid metal clad wire comprises a wire core and a cladding, wherein the cladding partially or entirely wraps the wire core, and the cladding is one or more layers; the wire core and the cladding are made of different types of liquid metal elements. The clad wire of the present invention is in a solid state before use, and after packaging, the metal mixture is finally alloyed to form liquid metal through a variety of heating methods, thereby avoiding leakage of liquid metal during circuit manufacturing.

Description

Technical Field

[0001] The invention belongs to the technical field of metal materials, and in particular relates to a liquid metal clad wire and a preparation method thereof. Background Art

[0002] Liquid metal alloy (such as gallium-indium alloy, gallium-indium-tin alloy) is a metal alloy that is in a flowing state at room temperature, and its melting point can be reduced to as low as 15°C, so liquid metal alloy has a wide range of applications in the field of flexible electronic devices. In the prior art, liquid metal alloys are mainly added to flexible devices in a liquid state to play a conductive role. However, the surface tension of liquid metal alloys is very large, even more than 10 times that of water, and the diameter of the circuit in the flexible device is usually very small. The liquid metal is prone to shrinkage during the process of making the circuit, which can easily lead to a short circuit. Therefore, the process of preparing conductive paths with liquid metal alloys is quite difficult. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a liquid metal clad wire, comprising:

[0004] Wire core;

[0005] A cladding layer, covering part or all of the core, wherein the cladding layer is one or more layers;

[0006] The core and the cladding are made of different types of liquid metal elements.

[0007] In order to solve the problem that the liquid metal alloy has high surface tension and is not easy to disperse evenly during its flow, the inventors thought of first turning it into a solid state by cooling it down, and then turning it into a liquid state by heating it after laying it into a line. However, the melting point of liquid metal alloys is generally low, so if the liquid metal alloy is directly solidified, it needs to be laid at low temperature, which increases the difficulty of laying. The inventors further thought of laying the metal elements that make up the liquid metal alloy separately after solidifying at low temperature, but the mechanical properties of the liquid metal element are poor after solidification, and it is easy to break during the deformation process. After laying, the metal element needs to be directly alloyed in the flexible material, so different metal elements need to be evenly mixed together, which involves the operation of laying a strand or merging multiple wires, and in this process, the wires of the liquid metal element are prone to breakage. In response to the above-mentioned problems, the present invention proposes the above-mentioned metal cladding material structure. By designing this cladding structure, different metal elements can be more evenly mixed, which is beneficial to the subsequent alloying, and can avoid complex installation methods such as twisting or merging the solid liquid metal. It can solve the problem of poor mechanical properties of solid liquid metal, facilitate installation, and greatly simplify the operating steps.

[0008] Preferably, the core and the cladding are made of liquid metal, and the melting point of the liquid metal gradually decreases from the core to the outside, which is conducive to the processing and forming of the liquid metal wire.

[0009] Preferably, micro-nanoparticles having photothermal functions are distributed in the outermost cladding.

[0010] Preferably, the micro-nano particles with photothermal function are iron nanoparticles or ferroferric oxide nanoparticles. Adding micro-nano particles with photothermal function to the outermost material can directly heat the wire to melt it by light, solving the problem that some flexible devices are not suitable for heating.

[0011] The present invention also provides a method for preparing the liquid metal clad wire of the present invention, comprising the following steps:

[0012] 1) Adjusting the temperature so that the cladding material is in liquid state and the temperature of the core is lower than the melting point of the cladding material;

[0013] 2) Covering the cladding material on the surface of the core.

[0014] The temperature of the wire core is lower than that of the cladding metal material, and the liquid cladding material can solidify on the surface of the wire core after coating, which is conducive to effective adhesion.

[0015] Preferably, the specific operation of covering the surface of the core with the cladding material is to immerse the core in the liquid cladding material and pull it upward so that the cladding material is wrapped around the surface of the core. Liquid metal has a high viscosity and it is difficult to directly and evenly coat the surface of the core. The above method is conducive to evenly covering the surface of the core with the cladding material, which is conducive to subsequent alloying, ensuring the uniformity of the material of the liquid metal alloy and ensuring good conductivity.

[0016] Preferably, when preparing multiple claddings, the wire coated with at least one cladding is cooled to a temperature lower than the melting point of the liquid metal to be coated, immersed in the liquid metal to be coated, and slowly pulled upward.

[0017] Preferably, the temperature of the core is adjusted to be 20-60° C. lower than the melting point of the cladding metal.

[0018] Preferably, the temperature of the inner layer covered wire is adjusted to be 20 to 60° C. lower than the melting point of the metal of the outer layer covered wire.

[0019] Under the above temperature difference, it is conducive for the liquid cladding material to solidify quickly on the surface of the solid material.

[0020] Preferably, the material of the core is indium, the material of the cladding is gallium, the temperature of the core is adjusted to be 20-60°C lower than the melting point of the cladding metal, the diameter of the core is 0.1-2mm, and the upward pulling speed is 0.01m / s-1m / s.

[0021] The method described in the present invention can form cladding materials of different thicknesses by controlling the diameter of the wire core and different pulling speeds. For indium with a diameter of 0.1 to 2 mm, the above-mentioned pulling speed can form an alloy material with a gallium-indium mass ratio of 75.5:24.5 to 9:1.

[0022] Preferably, the material of the wire core described in the present invention is indium, zinc, bismuth or tin, and the material of the cladding wire described in the present invention is gallium, indium, bismuth, tin or zinc.

[0023] The present invention has the following beneficial effects:

[0024] The present invention forms a sandwich structure by melting a low melting point metal and then covering it on the surface of a higher melting point metal. This solid layered metal mixture is in a solid state before use. When the solid wire is laid in a flexible circuit or other electronic circuit, after packaging, the metal mixture is finally alloyed through a variety of heating methods to form a liquid metal. This avoids leakage of liquid metal during the circuit manufacturing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of liquid metal alloy wire.

[0026] Figure 2 This is the SEM image of gallium-clad indium wire.

[0027] Figure 3 This is the EDS analysis diagram of gallium-clad indium wire.

[0028] Figure 4 This is the SEM image of gallium-encapsulated indium-encapsulated bismuth alloy. DETAILED DESCRIPTION

[0029] The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0030] In the present invention, if the specific technology or conditions are not specified in the examples, the technology or conditions described in the literature in the field or the product instructions are used. If the manufacturer of the instruments is not specified, they are all conventional products that can be purchased through regular channels. The materials used in the present invention can be purchased in the general market.

[0031] Example 1

[0032] This embodiment provides a liquid metal clad wire (its structural schematic diagram is shown in Figure 1 ),include:

[0033] The wire core is made of metal indium;

[0034] The cladding is wrapped around the core and is made of metal gallium.

[0035] This embodiment also provides a method for preparing the above-mentioned wire material, comprising the following steps:

[0036] (1) Gallium metal is heated until it becomes liquid, and an indium wire with a diameter of 0.5 mm is cooled to -20°C;

[0037] (2) inserting the indium wire into liquid gallium and pulling it upward at a speed of 0.01 m / s to obtain a wire with a gallium-indium mass ratio of 8.2:1.

[0038] Figure 2 This is a SEM image of the above wire, from which it can be seen that the wire core is indeed wrapped with metal; Figure 3 This is the EDS analysis diagram of the above wire. It can be seen from the figure that indium is indeed wrapped by gallium.

[0039] Example 2

[0040] This embodiment provides a liquid metal wire, including:

[0041] The wire core is located at the center of the liquid metal cladding wire and is made of metallic bismuth;

[0042] The cladding 1 is wrapped around the core and is made of metal indium;

[0043] The cladding 2 is wrapped around the cladding 1 and is made of metal gallium;

[0044] This embodiment also provides a method for preparing the above-mentioned wire material, comprising the following steps:

[0045] (1) Gallium and indium metals are heated until they become liquid, and a bismuth wire with a diameter of 0.5 mm is cooled to -29°C;

[0046] (2) inserting the bismuth wire into liquid indium, pulling it upward at a speed of 0.05 m / s, and cooling it.

[0047] solidifying the indium layer;

[0048] (3) The wire is inserted into liquid gallium, pulled upward at a speed of 0.02 m / s, and cooled to solidify the gallium layer.

[0049] The above method obtains an alloy with a mass ratio of metal bismuth, indium and gallium of 3:22:75.

[0050] Figure 4 This is the SEM picture of the above wire. It can be seen from the figure that sheet wire can also be produced in this way.

[0051] Example 3

[0052] This embodiment provides a liquid metal wire, which is different from the embodiment 1 in that nano-iron with photothermal function is added after the outer metal is melted. The wrapping process is the same as the embodiment 1.

[0053] Experimental Example 1

[0054] 1) Encapsulating the wire described in Example 1 or Example 2 inside a flexible electronic device to obtain a stable structure.

[0055] 2) By externally heating the temperature to 90°C-120°C, the cladding wire quickly melts and alloys to form a liquid metal wire.

[0056] Experimental Example 2

[0057] 1) Encapsulate the wire described in Example 3 inside a flexible electronic device to obtain a stable structure.

[0058] 2) Through infrared light irradiation, the photothermal nanomaterials inside the metal generate heat, promoting alloying and forming liquid metal wire.

[0059] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A liquid metal clad wire, characterized in that: include: Wire core; A cladding layer, covering part or all of the core, wherein the cladding layer is one or more layers; The materials of the core and the cladding are different types of liquid metal elements; The outermost cladding is distributed with micro-nano particles having photothermal functions; The method for preparing the liquid metal clad wire comprises the following steps: 1) Adjusting the temperature so that the cladding material is in liquid state and the temperature of the core is lower than the melting point of the cladding material; 2) immersing the wire core into the liquid cladding material and pulling it upward so that the cladding material wraps around the surface of the wire core; 3) When preparing multiple claddings, the wire coated with at least one cladding is cooled to a temperature lower than the melting point of the liquid metal to be coated, and is immersed in the liquid metal to be coated and pulled upward; The material of the wire core is indium, the material of the cladding is gallium, the diameter of the wire core is 0.1-2 mm, and a pulling speed of 0.01 m / s-1 m / s is adopted to form an alloy material with a gallium-indium mass ratio of 75.5:24.5-9:

1.

2. The liquid metal clad wire according to claim 1, characterized in that: The materials of the core and the cladding are both liquid metal, and the melting point of the liquid metal gradually decreases from the core to the outside.

3. The liquid metal clad wire according to claim 1, characterized in that: The micro-nano particles with photothermal function are iron nanoparticles or ferroferric oxide nanoparticles.

4. The method for preparing a liquid metal clad wire according to any one of claims 1 to 3, characterized in that: The steps include: 1) Adjusting the temperature so that the cladding material is in liquid state and the temperature of the core is lower than the melting point of the cladding material; 2) immersing the wire core into the liquid cladding material and pulling it upward so that the cladding material wraps around the surface of the wire core; 3) When preparing multiple claddings, the wire coated with at least one cladding is cooled to a temperature lower than the melting point of the liquid metal to be coated, and is immersed in the liquid metal to be coated and pulled upward; The material of the wire core is indium, the material of the cladding is gallium, the diameter of the wire core is 0.1-2 mm, and a pulling speed of 0.01 m / s-1 m / s is adopted to form an alloy material with a gallium-indium mass ratio of 75.5:24.5-9:

1.

5. The preparation method according to claim 4, characterized in that: The temperature of the core is adjusted to be 20-60°C lower than the melting point of the cladding metal, and / or the temperature of the inner cladding wire is adjusted to be 20-60°C lower than the melting point of the metal of the outer cladding wire.

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