A method for jetting liquid metal without nozzles driven by double-pulse laser

Abstract

The present invention discloses a method for jetting liquid metal without nozzles driven by double-pulse laser, comprising the following steps: Step 1: Place the liquid metal to be transferred in a transparent container box; Step 2: Place a transparent receiving substrate parallel to the upper part of the liquid metal; Step 3: Set up a laser emitting device, and the laser emitting device is located above the receiving substrate; Step 4: The laser emitting device emits two laser pulses successively; Step 5: An elongated metal jet perpendicular to the liquid metal surface is generated on the liquid metal surface, and the metal jet reaches the transparent substrate to form metal micro-droplets. The present invention uses double-pulse laser to irradiate the liquid metal surface, can achieve directional jet of liquid metal without nozzles and complex driving mechanisms, does not have the problems of nozzle blockage and metal corrosion of the nozzle head, and can realize efficient printing of two-dimensional patterns and three-dimensional structures of metal materials.

Description

Technical Field

[0001] The present invention belongs to the technical fields of printed electronics and metal additive manufacturing, and particularly relates to a method for jetting liquid metal without nozzles driven by a double-pulse laser. Background Art

[0002] Additive manufacturing technology is a technology for manufacturing objects by adding materials layer by layer. This technology can build objects layer by layer through digital design and control to manufacture objects with complex shapes, and is applied in fields such as industrial manufacturing, medical treatment, aerospace, architecture, and art.

[0003] Currently, the more widely applied metal additive technologies include micro-droplet jetting-based metal droplet jetting technologies represented by binder jetting, metal nanoparticle jetting, and high-temperature metal droplet jetting.

[0004] Among them, the binder jetting-based metal additive manufacturing technology is a product of the combination of high-efficiency digital inkjet printing technology and powder metallurgy technology. It uses one or more arrayed nozzles integrated with thousands of nozzles to jet the binder layer by layer onto the powder bed. The binder jetting and powder spreading are alternated to make the metal powder bond and form a shape. Then, the three-dimensional component formed by bonding is placed in a high-temperature furnace for debinding and sintering to improve its density.

[0005] The metal nanoparticle jetting-based metal additive manufacturing technology makes the metal material to be printed into nanoparticles and suspends them in an ink that can be inkjet printed. Then, using an arrayed nozzle, it is printed onto a substrate at a relatively high temperature to quickly volatilize the solvent in the ink, so that only metal nanoparticles and a small amount of non-volatile organic substances remain in the printed area. Layer-by-layer printing can make the metal nanoparticles accumulate to form a three-dimensional structure. Then, through high-temperature debinding and sintering, the density and mechanical strength of the printed component are improved.

[0006] The metal additive manufacturing technology of droplet jetting mainly has two types: continuous flow droplet jetting and on-demand droplet jetting.

[0007] The metal additive manufacturing technology of continuous flow droplet jetting is a technology that uses air pressure jetting power to jet molten metal through nozzles. During the jetting process, a periodic perturbation is applied to the jet through a piezoelectric ceramic or other vibration elements, so that the jet accelerates and breaks into independent droplets under the action of the Rayleigh-Plateau effect. Its principle is basically the same as that of continuous flow inkjet printing. Although the continuous flow jetting efficiency is relatively high, due to the difficulty in controlling the flight trajectory of its droplets and the need to use a recovery device to recover and process a large number of useless droplets, it not only results in a low utilization rate of droplets, but also increases the complexity of the nozzle structure and the difficulty of controlling the printing movement.

[0008] The metal additive manufacturing methods of on-demand droplet ejection include piston extrusion type, pneumatic pulse type, and electromagnetic pulse type. These three methods respectively use a piston (driven by piezoelectric ceramics or other actuating elements), high-pressure gas, and electromagnetic coils as actuating elements to generate an instantaneous pressure pulse in a relatively closed liquid storage cavity, so that the high-temperature liquid metal is ejected from the nozzle to form droplets.

[0009] However, the above-mentioned metal melting and spraying technologies based on nozzles all have the problem of complex nozzle structures. At the same time, the nozzles also have the risk of blockage, and the working stability is not high.

[0010] Based on the above problems, this application proposes a method for jetting liquid metal without nozzles driven by double-pulse lasers, which realizes the jetting of metal micro-droplets without nozzles without the need for a nozzle, thus avoiding the problems of complex nozzle structures and nozzle blockages. Summary of the Invention

[0011] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a method for jetting liquid metal without nozzles driven by double-pulse lasers.

[0012] To achieve the above purpose, the present invention adopts the following technical solutions:

[0013] A method for jetting liquid metal without nozzles driven by double-pulse lasers includes the following steps:

[0014] Step 1: Place the liquid metal to be transferred in a transparent container box so that the liquid metal forms a horizontal metal liquid surface under the action of gravity;

[0015] Step 2: Place a transparent receiving substrate parallel above the liquid metal, and the distance between the receiving substrate and the metal liquid surface is h;

[0016] Step 3: Set up a laser emission device, and the laser emission device is located above the receiving substrate;

[0017] Step 4: The laser emission device emits two laser pulses successively. The energy of the second laser pulse is not less than that of the first laser pulse, and through the galvanometer reflection and field lens focusing of the laser emission device, the two laser pulses act on the same position on the surface of the liquid metal;

[0018] Step 5: An elongated metal jet perpendicular to the metal liquid surface is generated on the surface of the liquid metal, and the metal jet reaches the transparent substrate and coalesces to form metal micro-droplets.

[0019] Preferably, in the above step 2, the distance h between the receiving substrate and the liquid metal surface is 1-20 cm.

[0020] Preferably, in the above step 4, the energy of the first laser pulse is 0.05-0.5 mJ, and the pulse width is 1 ps-1000 ns;

[0021] The energy of the second laser pulse is 0.3 - 1.5 mJ, and the pulse width is 1 ps - 1000 ns;

[0022] The energy difference between the second laser pulse and the first laser pulse is 0 - 1 mJ;

[0023] The time interval Δt between the first laser pulse and the second laser pulse is 20 - 100 μs.

[0024] Preferably, in step 4, the angle between the laser pulse and the normal direction of the liquid metal surface is 0 - 15°.

[0025] Preferably, in step 4, the laser used in the laser emission device is a nanosecond laser or a picosecond laser.

[0026] Preferably, the liquid metal to be transferred is gallium-based liquid metal or molten liquid metal.

[0027] The present invention also provides an application of a double-pulse laser-driven liquid metal non-orifice jetting method.

[0028] Application of the double-pulse laser-driven liquid metal non-orifice jetting method in printing technology.

[0029] The beneficial effects of the present invention are:

[0030] (1) By using double-pulse laser to irradiate the liquid metal surface, the present invention can achieve the directional jet of liquid metal, and any position on the liquid metal surface can be used as the jetting position; the present invention can achieve the directional jet of liquid metal without nozzles and complex driving mechanisms, there are no problems of nozzle blockage and metal corrosion of the nozzle, and it can achieve the high-efficiency printing of two-dimensional patterns and three-dimensional structures of metal materials.

[0031] (2) The jetting process of the present invention is simple to operate and easy to control; for the directional jet of the double-pulse laser-driven liquid metal of the present invention, the single-jet volume is about several nanoliters to dozens of nanoliters, and the jetting height can reach dozens of centimeters; the present invention improves the deposition efficiency of metal printing and the flight distance of the liquid metal jet, so it can allow a larger undulation height of the printing surface, thereby achieving deposition on complex curved surfaces. Description of the Drawings

[0032] The specification drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application.

[0033] Figure 1It is the state diagram at each stage photographed by a camera that forms metal micro - droplets by the method of non - orifice jetting of liquid metal driven by the dual - pulse laser of the present invention;

[0034] Figure 2 It is the microscopic display diagram of each state that forms metal micro - droplets by the method of non - orifice jetting of liquid metal driven by the dual - pulse laser of the present invention;

[0035] Figure 3 It is the schematic diagram of the non - orifice jetting device of normal - temperature liquid metal driven by a single - laser dual - pulse laser in an air environment in Example 2;

[0036] Figure 4 It is the linear dot - matrix pattern in Example 2;

[0037] Figure 5 It is the schematic diagram of the non - orifice jetting device of normal - temperature liquid metal driven by a dual - laser dual - pulse laser in an air environment in Example 3;

[0038] Figure 6 It is the vector dot - matrix pattern in Example 3;

[0039] Figure 7 It is the schematic diagram of the non - orifice jetting device of high - temperature molten liquid metal driven by a single - laser dual - pulse laser in an air environment in Example 4;

[0040] Figure 8 It is the linear dot - matrix pattern in Example 4;

[0041] Figure 9 It is the schematic diagram of the non - orifice jetting device of high - temperature molten liquid metal driven by a dual - laser dual - pulse laser in an air environment in Example 5;

[0042] Figure 10 It is the vector dot - matrix pattern in Example 5;

[0043] Figure 11 It is the schematic diagram of the non - orifice jetting device of high - temperature molten liquid metal driven by a single - laser dual - pulse laser in an acidic and anoxic environment in Example 6;

[0044] Figure 12 It is the schematic diagram of the non - orifice jetting device of high - temperature molten liquid metal driven by a dual - laser dual - pulse laser in an acidic and anoxic environment in Example 7;

[0045] Wherein:

[0046] 1 - computer, 2 - laser, 3 - laser galvanometer and field lens system, 4 - three - axis moving platform, 5 - quartz glass substrate, 6 - liquid metal, 7 - container box, 8 - heating device, 9 - sealing cover, 10 - ventilation duct. Detailed implementation manners

[0047] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs.

[0048] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0049] In the present invention, terms such as "upper", "lower", "bottom", "top", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only relational terms determined for the convenience of describing the structural relationship of each component or element of the present invention and do not specifically refer to any component or element in the present invention and should not be construed as a limitation on the present invention.

[0050] In the present invention, terms such as "connected" and "coupled" should be understood in a broad sense and may mean a fixed connection, an integral connection or a detachable connection; it may be directly connected or indirectly connected through an intermediate medium. For those skilled in the relevant scientific research or technology in this field, the specific meanings of the above terms in the present invention can be determined according to specific circumstances and should not be construed as a limitation on the present invention.

[0051] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0052] Embodiment 1:

[0053] A method for jetting liquid metal without nozzles driven by a double-pulse laser includes the following steps:

[0054] Step 1: Place the liquid metal to be transferred in a transparent container box so that the liquid metal forms a horizontal metal liquid surface under the action of gravity;

[0055] Step 2: Place a transparent receiving substrate parallel above the liquid metal, and the distance between the receiving substrate and the metal liquid surface is h;

[0056] Step 3: Set up a laser emitting device, and the laser emitting device is located above the receiving substrate;

[0057] Step 4: The laser emitting device emits two laser pulses successively. The energy of the second laser pulse is not less than that of the first laser pulse, and through the galvanometer mirror reflection and field lens focusing of the laser emitting device, the two laser pulses act on the same position on the surface of the liquid metal;

[0058] Step 5: Elongated metal jets perpendicular to the liquid metal surface are generated on the liquid metal surface, and the metal jets reach the transparent substrate and coalesce to form metal micro-droplets.

[0059] Preferably, in the step 2, the distance h between the receiving substrate and the liquid metal surface is 1-20 cm.

[0060] Preferably, in the step 4, the energy of the first laser pulse is 0.05-0.5 mJ, and the pulse width is 1 ps-1000 ns;

[0061] The energy of the second laser pulse is 0.3-1.5 mJ, and the pulse width is 1 ps-1000 ns;

[0062] The energy difference between the second laser pulse and the first laser pulse is 0-1 mJ;

[0063] The time interval Δt between the first laser pulse and the second laser pulse is 20-100 us.

[0064] Preferably, in the step 4, the angle between the laser pulse and the normal of the liquid metal surface is 0-15°.

[0065] Preferably, in the step 4, the laser used in the laser emission device is a nanosecond laser or a picosecond laser.

[0066] Preferably, the liquid metal to be transferred is a gallium-based liquid metal or a molten liquid metal, such as a molten tin-lead alloy, a molten liquid copper, a molten liquid iron, or a molten liquid aluminum.

[0067] In the nozzleless spraying method of the present application, when the first laser pulse is focused and irradiated on the liquid metal surface, the laser energy acts instantaneously on the liquid metal surface, generating a high-pressure plasma at the irradiation point. The pictures taken by the camera are as shown in A in Figure 1 , and its microscopic display is as shown in A in Figure 2 ;

[0068] Under the high pressure of the plasma, a small crater-like pit is formed at the irradiation point on the liquid metal surface. The pictures taken by the camera are as shown in B in Figure 1 , and its microscopic display is as shown in B in Figure 2 ;

[0069] When the height difference between the bottom and the edge of the crater-like small pit reaches the maximum, the second laser pulse enters the bottom through the small crater, generating a high-pressure plasma again above the concave liquid surface. The pictures taken by the camera are as shown in C in Figure 1 , and its microscopic display is as shown in Figure 2as shown by C in

[0070] Under the action of high-pressure plasma, the small "crater" further expands around. On the other hand, the high pressure acts on the concave liquid surface, causing the internal pressure of the local metal below the concave liquid surface to rise sharply, thereby generating a slender metal jet at the bottom of the concave liquid surface. The direction of the jet is perpendicular to the upper surface of the liquid metal, and its speed is dozens to more than one hundred meters per second. The pictures taken by the camera are as shown in Figure 1 D in Figure 2 as shown by D in

[0071] At the end of the high-speed jet, a thick jet will be generated from its bottom, the "crater" will collapse, and the liquid surface oscillation will last for about 1 millisecond. The pictures taken by the camera are as shown in Figure 1 E in Figure 2 as shown by E in

[0072] The thick jet will disappear after several oscillations, the surface of the liquid metal will return to calm, and at the same time, a grayish-white oxide film layer will be left at the original position. The pictures taken by the camera are as shown in Figure 1 F in Figure 2 as shown by F in

[0073] Example 2:

[0074] Application of the double-pulse laser-driven liquid metal non-orifice jetting method in Example 1 in printing technology.

[0075] In an air environment, the laser emission device uses a single laser. The double-pulse laser emitted by the single laser is used to drive the non-orifice jetting method of room-temperature liquid metal gallium-indium alloy to achieve two-dimensional printing. The Figure 3 non-orifice jetting device of room-temperature liquid metal driven by a single laser with double pulses in the air environment shown in Figure 3 is used for implementation. In

[0076] Step 11: In an air environment, place the room-temperature liquid metal gallium-indium alloy in the transparent container box 7 so that the upper surface of the liquid metal gallium-indium alloy is well paved into a layer;

[0077] Step 12: Take the transparent quartz glass substrate 5 as the receiving substrate and fix it on the three-axis displacement platform 4, place the transparent quartz glass substrate 5 parallel above the liquid metal 6, and the distance h between the transparent quartz glass substrate 5 and the upper surface of the liquid metal 6 is 5 cm;

[0078] Step 13: Control the laser 2 by the computer 1 to generate two pulsed lasers. Through the galvanometer mirror reflection and field lens focusing of the laser galvanometer and field lens system 3, make the two laser pulses act on the same position on the surface of the liquid metal; specifically set the laser output frequency to 10 kHz, the opening time of the laser 2 to 200 us, and generate two laser pulses with a time interval of 100 us; the pulse widths of the two laser pulses are both 500 ns and the energies are both 0.5 mJ;

[0079] Step 14: Elongated metal jets perpendicular to the metal liquid surface are generated on the surface of the liquid metal gallium-indium alloy, and the metal jets reach the transparent quartz glass substrate 5 to form metal micro-droplets;

[0080] Step 15: The computer 1 controls the three-axis displacement platform 4 to drive the transparent quartz glass substrate 5 to move in the horizontal plane and controls the position of the double-pulse laser irradiation on the liquid metal;

[0081] Step 16: Repeat Step 13 to Step 15 to achieve two-dimensional printing on the transparent quartz glass substrate 5.

[0082] When the computer 1 controls the three-axis displacement platform 4 to drive the quartz glass substrate 5 to move linearly, a linear dot matrix pattern as shown in Figure 4 is printed on the transparent quartz glass substrate 5.

[0083] Example 3:

[0084] Application of the liquid metal non-nozzle jetting method driven by double-pulse laser in Example ① in printing technology.

[0085] Under an air environment, the laser emission device uses two lasers, and the two lasers emit double-pulse lasers to drive the non-nozzle jetting method of room-temperature liquid metal gallium-indium alloy to achieve two-dimensional printing. The Figure 5 non-nozzle jetting device of room-temperature liquid metal driven by double-laser double-pulse laser under the air environment in Figure 5 is used for implementation. In Figure 5 , the liquid metal 6 is contained in a transparent square box 7, the quartz glass substrate 5 is the receiving substrate, the quartz glass substrate 5 is located above the liquid metal 6 and is fixedly arranged on the three-axis moving platform 4; the laser emission device is two lasers 2, and the two lasers 2 and their laser galvanometer and field lens system 3 are located above the quartz glass substrate 5, and the computer 1 is connected to the lasers 2 and the three-axis moving platform 4; the lasers 2 can irradiate different positions on the surface of the liquid metal 6 through the adjustment of the laser galvanometer and field lens system 3. The specific steps are as follows:

[0086] Step 21: In an air environment, place the room-temperature liquid metal 6, gallium-indium alloy, in a transparent container box 7 so that the upper surface of the liquid metal gallium-indium alloy is laid out in a good flat layer;

[0087] Step 22: Take the transparent quartz glass substrate 5 as the receiving substrate and fix it on the three-axis displacement platform 4, place the transparent quartz glass substrate 5 parallel above the liquid metal, and the distance h between the upper surface of the transparent quartz glass substrate 5 and the upper surface of the liquid metal 6 is 1 cm;

[0088] Step 23: Control the computer 1 to generate a pulsed laser in front and behind respectively by two lasers 2. Through the galvanometer mirror reflection and field lens focusing of the laser galvanometer and field lens system 3, make the two laser pulses act on the same position on the liquid metal surface;

[0089] The energy of the first laser pulse is 0.05 mJ and the pulse width is 300 ns;

[0090] The energy of the second laser pulse is 0.3 mJ and the pulse width is 500 ns;

[0091] The time interval Δt between the first laser pulse and the second laser pulse is 20 μs.

[0092] Step 24: Elongated metal jets perpendicular to the metal liquid surface are generated on the surface of the liquid metal gallium-indium alloy, and the metal jets reach the transparent quartz glass substrate 5 to form metal micro-droplets;

[0093] Step 25: The computer 1 controls the three-axis displacement platform 4 to drive the transparent quartz glass substrate 5 to move in the horizontal plane and controls the position of the double-pulse laser irradiation on the liquid metal;

[0094] Step 26: Repeat Step 23 to Step 25 to achieve two-dimensional printing on the transparent quartz glass substrate 5.

[0095] When the computer 1 controls the three-axis displacement platform 4 to drive the quartz glass substrate 5 to perform vector dot matrix movement, a vector dot matrix pattern as shown in Figure 6 is printed on the transparent quartz glass substrate 5.

[0096] Example 4:

[0097] Application of the double-pulse laser-driven liquid metal non-nozzle jetting method in Example 1 in printing technology.

[0098] In an air environment, the laser emission device uses a single laser, and uses the single laser to emit double-pulse laser to drive the non-nozzle jetting method of molten tin-lead alloy to achieve two-dimensional printing. Figure 7Implement it with a high-temperature molten liquid metal non-orifice injection device driven by a single laser double-pulse laser in an air environment. Figure 7 In this case, the liquid metal 6 is a molten tin-lead alloy, which is placed in a transparent container box 7. The quartz glass substrate 5 is a receiving substrate. The quartz glass substrate 5 is located above the liquid metal 6 and is fixedly arranged on the three-axis moving platform 4. The laser emission device is a single laser 2. The laser 2 and its laser galvanometer and field lens system 3 are located above the quartz glass substrate 5. The computer 1 is connected to the laser 2 and the three-axis moving platform 4. The laser 2 can irradiate different positions on the surface of the liquid metal 6 through the adjustment of the laser galvanometer and field lens system 3. The container box 7 is placed on the heating device 8. The specific steps are as follows:

[0099] Step 31: In an air environment, place the molten tin-lead alloy in the transparent container box 7, and uniformly heat and melt the tin-lead alloy in the container box 7 through an asbestos net, so that the upper surface of the molten tin-lead alloy is preferably paved into a flat layer.

[0100] Step 32: Use the transparent quartz glass substrate 5 as the receiving substrate and fix it on the three-axis displacement platform 4, so that the transparent quartz glass substrate 5 is placed parallel above the liquid metal 6. The distance h between the transparent quartz glass substrate 5 and the upper surface of the liquid metal 6 is 10 cm.

[0101] Step 33: Control the laser 2 to generate two pulsed lasers through the computer 1. Through the galvanometer reflection and field lens focusing of the laser galvanometer and field lens system 3, make the two laser pulses act on the same position on the surface of the liquid metal. Specifically, set the laser output frequency to 40 kHz, the opening time of the laser 2 to 50 us, and generate two laser pulses with a time interval of 25 us. The pulse widths of the two laser pulses are both 500 ns and the energies are both 0.5 mJ.

[0102] Step 34: Elongated metal jets perpendicular to the metal liquid surface are generated on the surface of the molten tin-lead alloy, and the metal jets reach the transparent quartz glass substrate 5 to form metal micro-droplets.

[0103] Step 35: The computer 1 controls the three-axis displacement platform 4 to drive the transparent quartz glass substrate 5 to move in the horizontal plane and controls the position where the laser double pulse irradiates on the liquid metal.

[0104] Step 36: Repeat steps 33 to 35 to achieve two-dimensional printing on the transparent quartz glass substrate 5.

[0105] When the computer 1 controls the three-axis displacement platform 4 to drive the quartz glass substrate 5 to perform a linear movement, a linear dot matrix pattern as shown in Figure 8 is printed on the transparent quartz glass substrate 5.

[0106] Example 5:

[0107] Application of the double-pulse laser-driven liquid metal non-orifice jetting method in Example 1 in printing technology.

[0108] In an air environment, the laser emission device uses two lasers. The double-pulse laser emitted by the two lasers is used to drive the non-orifice jetting method of molten tin-lead alloy to achieve two-dimensional printing. The Figure 9 high-temperature molten liquid metal non-orifice jetting device driven by double lasers and double-pulse lasers in the air environment in is used for implementation. Figure 9 In, the liquid metal 6 is molten tin-lead alloy, which is contained in a transparent square box 7. The quartz glass substrate 5 is the receiving substrate. The quartz glass substrate 5 is located above the liquid metal 6 and is fixedly arranged on the three-axis moving platform 4; the laser emission device is two lasers 2. The two lasers 2 and their laser galvanometer and field lens systems 3 are located above the quartz glass substrate 5. The computer 1 is connected to the lasers 2 and the three-axis moving platform 4; the lasers 2 can irradiate different positions on the surface of the liquid metal 6 through the adjustment of the laser galvanometer and field lens system 3. The container box 7 is placed on the heating device 8. The specific steps are as follows:

[0109] Step 41: In an air environment, place the molten tin-lead alloy in the transparent container box 7, and uniformly heat and melt the tin-lead alloy in the container box 7 through an asbestos net, so that the upper surface of the molten tin-lead alloy is well spread into a layer;

[0110] Step 42: Use the transparent quartz glass substrate 5 as the receiving substrate and fix it on the three-axis displacement platform 4, so that the transparent quartz glass substrate 5 is placed parallel above the liquid metal 6, and the distance h between the transparent quartz glass substrate 5 and the upper surface of the liquid metal 6 is 20 cm;

[0111] Step 43: Control the two lasers 2 to generate a pulse laser each before and after through the computer 1. Through the galvanometer reflection and field lens focusing of the laser galvanometer and field lens system 3, the two laser pulses act on the same position on the surface of the liquid metal;

[0112] The energy of the first laser pulse is 0.5 mJ, and the pulse width is 300 ns;

[0113] The energy of the second laser pulse is 1.5 mJ, and the pulse width is 500 ns;

[0114] The time interval Δt between the first laser pulse and the second laser pulse is 50 μs.

[0115] Step 44: An elongated metal jet perpendicular to the metal liquid surface is generated on the surface of the molten tin-lead alloy, and the metal jet reaches the transparent quartz glass substrate 5 to form metal micro-droplets;

[0116] Step 45: The computer 1 controls the three-axis displacement platform 4 to drive the transparent quartz glass substrate 5 to move in the horizontal plane and controls the position where the laser double pulse irradiates on the liquid metal.

[0117] Step 46: Repeat Step 43 to Step 45 to achieve two-dimensional printing on the transparent quartz glass substrate 5.

[0118] When the computer 1 controls the three-axis displacement platform 4 to drive the quartz glass substrate 5 to perform vector dot matrix movement, a vector dot matrix pattern as shown in Figure 10 is printed on the transparent quartz glass substrate 5.

[0119] Example 6:

[0120] Application of the double-pulse laser-driven liquid metal non-orifice jetting method in Example 1 in printing technology.

[0121] In an acidic anaerobic environment, the laser emission device uses a single laser. The three-dimensional printing is realized by using the method of driving the molten tin-lead alloy to jet without an orifice by emitting double-pulse laser from a single laser. It is implemented by using the high-temperature molten liquid metal non-orifice jetting device driven by a single laser with double pulses in the acidic anaerobic environment in Figure 11 . In Figure 11 , the liquid metal 6 is molten tin-lead alloy, which is placed in a transparent container box 7. The quartz glass substrate 5 is a receiving substrate. The quartz glass substrate 5 is located above the liquid metal 6 and is fixedly arranged on the three-axis moving platform 4. The laser emission device is a single laser 2. The laser 2, its laser galvanometer and field lens system 3 are located above the quartz glass substrate 5. The computer 1 is connected to the laser 2 and the three-axis moving platform 4. The laser 2 can irradiate at different positions on the surface of the liquid metal 6 through the adjustment of the laser galvanometer and field lens system 3. The container box 7 is placed on the heating device 8. The three-axis moving platform 4 and its fixedly connected quartz glass substrate 5, container box 7 and the corresponding heating device 8 are all placed in the transparent sealed cover 9 in the acidic anaerobic environment. The sealed cover 9 conducts ventilation and air release through the ventilation pipe 10. The specific steps are as follows:

[0122] Step 51: Introduce acidic HCl gas into the sealed cover 9 to create an acidic anaerobic environment. In the acidic anaerobic gas environment, place the molten tin-lead alloy in the transparent container box 7, and uniformly heat and melt the tin-lead alloy in the container box 7 through an asbestos net, so that the upper surface of the molten tin-lead alloy is well paved into a layer. In the acidic anaerobic environment, there will be no oxide film on the surface of the molten metal, thus realizing the continuous in-situ jetting of the laser-driven molten tin-lead alloy.

[0123] Step 52: Take the transparent quartz glass substrate 5 as the receiving substrate and fix it on the three-axis displacement platform 4, place the transparent quartz glass substrate 5 parallel above the liquid metal 6, and the distance h between the transparent quartz glass substrate 5 and the upper surface of the liquid metal 6 is 5 cm;

[0124] Step 53: Control the laser 2 by the computer 1 to generate two pulsed lasers. Through the galvanometer mirror reflection and field lens focusing of the laser galvanometer and field lens system 3, make the two laser pulses act on the same position on the surface of the liquid metal; specifically set the laser output frequency to 10 kHz, the laser 2 turn-on time to 200 us, and generate two laser pulses with a time interval of 100 us; the pulse widths of the two laser pulses are both 500 ns and the energies are both 0.5 mJ;

[0125] Step 54: Elongated metal jets perpendicular to the metal liquid surface are generated on the surface of the molten tin-lead alloy, and the metal jets reach the transparent quartz glass substrate 5 to form metal micro-droplets;

[0126] Step 55: Repeat Step 53 to Step 54. The computer 1 controls the continuous irradiation of the double-pulse laser at the same position on the liquid metal and controls the number of irradiations, so that the molten tin-lead alloy is continuously deposited at the same vertical position on the quartz glass substrate 5, and the printing of the micro-column structure of the molten tin-lead alloy on the quartz glass substrate 5 is completed.

[0127] Example 7:

[0128] Application of the double-pulse laser-driven liquid metal non-orifice jetting method in Example 1 in printing technology.

[0129] In an acidic anaerobic environment, the laser emission device uses two lasers, and the three-dimensional printing is realized by using the double-pulse laser emitted by the two lasers to drive the non-orifice jetting method of the molten tin-lead alloy. Figure 12 Implement with the high-temperature molten liquid metal non-orifice jetting device driven by double lasers and double pulses in the acidic anaerobic environment in Figure 12 In it, the liquid metal 6 is molten tin-lead alloy, which is contained in the transparent square box 7. The quartz glass substrate 5 is the receiving substrate. The quartz glass substrate 5 is located above the liquid metal 6 and is fixedly arranged on the three-axis moving platform 4; the laser emission device is two lasers 2. The two lasers 2 and their laser galvanometer and field lens system 3 are located above the quartz glass substrate 5. The computer 1 is connected to the lasers 2 and the three-axis moving platform 4; the lasers 2 can irradiate different positions on the surface of the liquid metal 6 through the adjustment of the laser galvanometer and field lens system 3. The container box 7 is placed on the heating device 8; the three-axis moving platform 4 and the fixedly connected quartz glass substrate 5, container box 7 and the corresponding heating device 8 are all placed in the transparent sealed cover 9 in the acidic anaerobic environment. The sealed cover 9 is ventilated and deflated through the ventilation pipe 10. The specific steps are as follows:

[0130] Step 61: Introduce acidic HCl gas into the sealed cover 9 to create an acidic and oxygen-free environment; in the acidic and oxygen-free gas environment, place the molten tin-lead alloy in the transparent container box 7, and evenly heat and melt the tin-lead alloy in the container box 7 through an asbestos net, so that the upper surface of the molten tin-lead alloy is preferably laid flat in a layer; in the acidic and oxygen-free environment, there will be no oxide film on the surface of the molten metal, thus realizing the continuous in-situ jetting of the laser-driven molten tin-lead alloy.

[0131] Step 62: Use the transparent quartz glass substrate 5 as the receiving substrate and fix it on the three-axis displacement platform 4, place the transparent quartz glass substrate 5 parallel above the liquid metal 6, and the distance h between the transparent quartz glass substrate 5 and the upper surface of the liquid metal 6 is 1 cm.

[0132] Step 63: Control the computer 1 to generate a pulsed laser in front of and behind each of the two lasers 2. Through the galvanometer reflection and field lens focusing of the laser galvanometer and field lens system 3, make the two laser pulses act on the same position on the surface of the liquid metal.

[0133] The energy of the first laser pulse is 0.05 mJ, and the pulse width is 300 ns.

[0134] The energy of the second laser pulse is 0.3 mJ, and the pulse width is 500 ns.

[0135] The time interval Δt between the first laser pulse and the second laser pulse is 20 μs.

[0136] Step 64: Elongated metal jets perpendicular to the metal liquid surface are generated on the surface of the molten tin-lead alloy, and the metal jets reach the transparent quartz glass substrate 5 to form metal micro-droplets.

[0137] Step 65: The computer 1 controls the three-axis displacement platform 4 to drive the transparent quartz glass substrate 5 to move and controls the position where the double-pulse laser irradiates on the liquid metal.

[0138] Step 66: Repeat Step 63 to Step 65 to achieve three-dimensional printing on the transparent quartz glass substrate 5.

[0139] The present invention uses double-pulse laser irradiation on the surface of the liquid metal, which can realize the directional jetting of the liquid metal, and any position on the surface of the liquid metal can be used as the jetting position; the present invention can realize the directional jetting of the liquid metal without a nozzle and a complex driving mechanism, there are no problems of nozzle blockage and metal corrosion of the nozzle, and it can realize the efficient printing of two-dimensional patterns and three-dimensional structures of metal materials.

[0140] The jetting process of the present invention is simple to operate and easy to control; for the directional jet of liquid metal driven by double-pulse laser of the present invention, the volume of a single jet is about several nanoliters to dozens of nanoliters, and the jet height can reach dozens of centimeters; therefore, the present invention improves the deposition efficiency of metal printing and the flight distance of the liquid metal jet, so that a larger undulation height of the printing surface can be allowed, thereby realizing deposition on complex curved surfaces.

[0141] Although the specific implementation manners of the present invention are described above in conjunction with the accompanying drawings, they are not limitations on the present invention. Those skilled in the art should understand that various modifications or deformations that can be made without creative efforts on the basis of the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for jetting liquid metal without nozzles driven by double-pulse laser, characterized in that It includes the following steps: Step 1: Place the liquid metal to be transferred in a transparent container box so that the liquid metal forms a horizontal metal liquid surface under the action of gravity; Step 2: Place the transparent receiving substrate parallel above the liquid metal, and the distance between the receiving substrate and the metal liquid surface is h ; Step 3: Set up a laser emission device, and the laser emission device is located above the receiving substrate; Step 4: The laser emission device emits two laser pulses successively. The energy of the second laser pulse is not less than that of the first laser pulse, and through the galvanometer reflection and field lens focusing of the laser emission device, the two laser pulses act on the same position on the surface of the liquid metal; When the first laser pulse is focused and irradiated on the surface of the liquid metal, the laser energy acts on the surface of the liquid metal instantaneously, generating a high-pressure plasma at the irradiation point. Under the high pressure of the plasma, small pits are formed at the irradiation point on the surface of the liquid metal; The second laser pulse enters the bottom of the small pit, and a high-pressure plasma is generated again above the concave liquid surface. The high pressure acts on the concave liquid surface, causing the local metal internal pressure below the concave liquid surface to rise sharply, and generating a slender metal jet at the bottom of the concave liquid surface; Step 5: A slender metal jet perpendicular to the metal liquid surface is generated on the surface of the liquid metal, and the metal jet reaches the transparent substrate and coalesces to form metal micro-droplets; In the step 4, the energy of the first laser pulse is 0.05 - 0.5 mJ, and the pulse width is 1 ps - 1000 ns; The energy of the second laser pulse is 0.3 - 1.5 mJ, and the pulse width is 1 ps - 1000 ns; The energy difference between the second laser pulse and the first laser pulse is 0 - 1 mJ; The time interval between the first laser pulse and the second laser pulse is 20 - 100 us; In the step 2, the distance between the receiving substrate and the liquid metal surface h is 1 to 20 cm.

2. The double-pulse laser-driven liquid metal non-orifice jetting method according to claim 1, characterized in that In the step 4, the angle between the laser pulse and the normal direction of the liquid metal surface is 0 - 15°; 3. The method for jetting liquid metal without nozzles driven by double-pulse laser according to claim 1, wherein In the step 4, the laser used in the laser emission device is a nanosecond laser or a picosecond laser; 4. The double-pulse laser-driven liquid metal jetting method without nozzles according to claim 1, wherein The liquid metal to be transferred is gallium-based liquid metal or molten liquid metal; 5. Application of the double-pulse laser-driven liquid metal non-orifice jetting method according to any one of claims 1 - 4 in printing technology.

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