Method for casting liquid metal by ultrasonically driving and filling soluble resin mold

Abstract

The invention provides a method for casting liquid metal by ultrasonically driving and filling a soluble resin mold, which comprises the following steps of: S1, preparing a soluble sacrificial mold containing a channel according to a to-be-formed three-dimensional form; s2, the obtained sacrificial mold is fixed to a bottom plate, then the bottom plate is fixed to an ultrasonic clamp, ultrasonic waves are applied for 2 s or above through an ultrasonic probe, and the liquid metal is poured into the channel under the action of the ultrasonic waves; and S3, the mold is taken down, and the sacrificial mold is dissolved. By the adoption of the technical scheme, the liquid metal is poured into the mold channel in the mode that the sacrificial resin mold is combined with ultrasonic driving, the three-dimensional structure of the liquid metal can be maintained without structural collapse caused by melting of the liquid metal due to the fact that an excessive oxidation film is generated on the surface of the liquid metal through ultrasonic induction, and even if the sacrificial mold plate is dissolved, the liquid metal cannot be damaged. And under the condition that the liquid metal is still kept in the liquid state, the excessive oxidation film on the surface of the liquid metal can still support the structure not to collapse.

Description

Technical Field

[0001] The invention relates to the technical field of three-dimensional configuration of liquid metal, and in particular to a method for casting liquid metal by ultrasonically driving a soluble resin mold. Background Art

[0002] At present, most of the liquid metal patterning methods are aimed at plane processing, and there are few for liquid metal three-dimensional construction. 3D printing technology uses liquid metal oxide film to support its structure, but the oxide film is thin, only about 5 to 10nm thick, and has low mechanical strength (yield stress is about 0.5N / m), so it has great restrictions on the three-dimensional shape of liquid metal and cannot be arbitrarily configured. Specifically, its printed structure is mostly linear and the lines are thin (diameter less than 50μm), and the angle at the bend is small. If the amount of liquid metal printed is too large or the bending angle is too large, the oxide film will rupture and the structure will collapse. Therefore, it is very difficult to print LM into a large 3D structure under room temperature. The current molding height of the needle extrusion method and droplet accumulation method is about 1cm. At the same time, the literature shows that the speed of the nozzle lifting when doing liquid metal configuration needs to be controlled between 0.001-0.1mm / s to ensure that the adhesion energy between the liquid metal and the substrate is less than the fracture energy of the oxide film, so that the line will not break during the construction process. For the method of combining 3D printing with support medium, the nature of the support medium determines the printing quality. The accuracy and resolution of the printed structure are affected by the nozzle diameter, feed flow rate and printing speed, but it should be noted that the printed liquid metal is in a droplet state due to its extremely high surface tension, not a continuous metal line, and the printed droplets are not consistent in size.

[0003] The method of liquid processing solid forming, whether combined with 3D printing or mold casting, can only serve below the melting point of liquid metal, and has high requirements for ambient temperature conditions. If it is higher than the melting point of liquid metal, the excessive melting of liquid metal will cause the oxide film on its surface to be overwhelmed and eventually lead to structural collapse. At the same time, the mold casting method cannot construct complex structures, and can only obtain pure liquid metal three-dimensional structures with relatively regular shapes, because once the structure is complex, it is impossible to remove the mold while ensuring the integrity of the structure. Summary of the invention

[0004] In view of the above technical problems, the present invention discloses a method for casting liquid metal by ultrasonically driving a soluble resin mold filled therein, which solves the lack of current three-dimensional configuration methods for pure liquid metal.

[0005] To this end, the technical solution adopted by the present invention is:

[0006] A method for casting liquid metal by ultrasonically driving a soluble resin mold, comprising the following steps:

[0007] Step S1, using modeling software to perform modeling and slicing according to the three-dimensional shape to be formed, and using a 3D printer to print layer by layer to prepare a soluble, channel-containing sacrificial mold;

[0008] Step S2, fixing the obtained sacrificial mold on a base plate, and then fixing the base plate on an ultrasonic fixture, applying ultrasound for more than 2 seconds through an ultrasonic probe, so that the liquid metal is poured into the channel under the action of ultrasound;

[0009] Step S3, removing the mold and dissolving the sacrificial mold.

[0010] This technical solution uses a sacrificial mold combined with ultrasonic infusion to work synergistically. On the one hand, liquid metal can be infused into the channel of the sacrificial mold. On the other hand, during the ultrasonic infusion process, the ultrasound drives the liquid metal to move and produces additional oxides, so that an oxide film is formed on the surface of the infused liquid metal, thereby maintaining the three-dimensional structure of the liquid metal itself and preventing the structure from collapsing due to the melting of the liquid metal. The resulting liquid metal component is stable in shape and will not collapse in a 50°C water bath environment for 5 minutes.

[0011] As a further improvement of the present invention, step S1 includes:

[0012] Step S11, preparing a photocurable resin, wherein the components of the photocurable resin include a resin monomer, a photoinitiator and a photoinhibitor;

[0013] Step S12, using a 3D printer to print a sacrificial mold.

[0014] As a further improvement of the present invention, step S1 further includes:

[0015] Step S13, after removing the resin mold, use anhydrous ethanol to wash away the residual resin, and use ultraviolet light for secondary curing. This technical solution can prevent its fine structure from being dissolved in its monomer resin residual liquid or ethanol.

[0016] As a further improvement of the present invention, in step S11, the resin monomer is isobornyl acrylate, the photoinitiator is TPO-L, the mass of the photoinitiator is 0.5-5% of the mass of the resin monomer, the photoinhibitor includes at least one of curcumin and copper phthalocyanine, and the mass of the photoinhibitor is 0.02%-0.5% of the mass of the resin monomer. The resin monomer, the photoinitiator and the photoinhibitor are uniformly mixed to obtain a photocurable resin.

[0017] As a further improvement of the present invention, the clamp is a titanium alloy clamp or an aluminum alloy clamp.

[0018] As a further improvement of the present invention, in step S2, the ultrasonic power is 400-800W, and the ultrasonic time is 2-5s.

[0019] As a further improvement of the present invention, in step S3, water or dichloromethane is used to dissolve the sacrificial mold to obtain a formed liquid metal three-dimensional component.

[0020] As a further improvement of the present invention, the liquid metal is Ga-based liquid metal.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] By adopting the technical solution of the present invention, a sacrificial resin mold with a desired complex structure can be photocured through a 3D printing device. Liquid metal is poured into the interior of the mold channel by ultrasonic drive, and ultrasonic methods can be used to effectively fill complex interlaced channels. The use of ultrasonic drive to fill liquid metal can not only achieve the filling of complex structures of interlaced channels that cannot be achieved by injection methods, but also induce the production of excessive oxide film on the surface of the liquid metal to maintain the three-dimensional structure of the liquid metal itself without causing structural collapse due to the melting of the liquid metal. Even if the sacrificial template is dissolved and the liquid metal remains in a liquid state, the excessive oxide film on its surface can still support the structure from collapsing, thereby achieving a complex configuration of a pure liquid metal three-dimensional structure, which is impossible to achieve with traditional injection methods and vacuum methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of a method for casting liquid metal by ultrasonically driving a soluble resin mold filled according to an embodiment of the present invention.

[0024] Figure 2 This is a result diagram of the ultrasonically driven filling channel according to an embodiment of the present invention.

[0025] Figure 3 This is a result diagram of the sacrificial resin mold of an embodiment of the present invention after swelling in dichloromethane for 4 hours.

[0026] Figure 4 This is a diagram of the three-dimensional casting result of liquid metal obtained in an embodiment of the present invention.

[0027] Figure 5 This is a graph showing the effect of 600W ultrasonic power on the viscosity of liquid metal after 2s and 5s in an embodiment of the present invention.

[0028] Figure 63 and 4. The figures are comparative diagrams of the liquid metal solid spirals obtained by ultrasonic driving and injection method of the present invention, wherein (a) is the result diagram of the liquid metal solid spiral obtained by ultrasonic driving at room temperature, (b) is the result diagram of the liquid metal solid spiral obtained by ultrasonic driving after 5 minutes in a 50°C water bath environment, (c) is the result diagram of the liquid metal solid spiral obtained by traditional injection method at room temperature, and (d) is the result diagram of the liquid metal solid spiral obtained by traditional injection method after 5 minutes in a 50°C water bath environment.

[0029] Figure 7 The embodiment of the present invention adopts ultrasonic driving filling channel to prepare liquid metal solid two-layer lattice, three-layer lattice and football C 60 Structural result diagram; (a) is a two-layer lattice structure, (b) is a three-layer lattice structure, and (c) is a football C 60 structure.

[0030] Reference numerals include:

[0031] 1-Sacrificial resin mold, 2-Acrylic plate, 3-Bolt, 4-Titanium alloy fixture, 5-Ultrasonic probe. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present invention are described in further detail below.

[0033] In order to achieve high-precision three-dimensional casting of pure liquid metal, this embodiment discloses a method for casting liquid metal by ultrasonically driving a soluble resin mold, which specifically includes:

[0034] First, a sacrificial mold that can be dissolved under mild conditions needs to be obtained. The preparation of this sacrificial mold is divided into two steps.

[0035] The first step is to prepare the photocurable resin: the photocurable resin generally contains four parts, namely the matrix monomer (the matrix monomer is cured through free radical polymerization under the action of the photoinitiator to form a cross-linked polymer network), the photoinitiator (which can produce free radicals under ultraviolet or visible light irradiation to start the polymerization reaction of the matrix monomer. Its selection and dosage will affect the curing speed and depth), the photoinhibitor (which controls the polymerization rate to prevent the photocuring reaction from being too fast, resulting in uneven material properties or surface defects. The photoinhibitor can capture free radicals and delay the reaction), and the stabilizer (used to improve the storage stability of the photocurable resin and prevent unwanted polymerization reactions during storage. They can capture low-energy free radicals or react with oxygen, thereby extending the service life of the resin).

[0036] In this embodiment, isobornyl acrylate (IBOA) is selected as the resin base, and the photoinitiator TPO-L (0.5-5%) and the photoinhibitor curcumin and copper phthalocyanine (0.02%-0.5%) are added and fully mixed to form a uniform solution. The specific ratio is selected according to the parameters of the 3D printer itself.

[0037] The second step is to use a 3D printer to print a sacrificial mold: Use modeling software to model and slice according to the three-dimensional form to be formed, and put the configured soluble resin into the resin tank of a high-precision 3D printer for 3D printing. Under the processing of a high-precision 3D printer, ultra-fine structure printing with an XY plane accuracy of 10μm and a Z axis accuracy of 25μm is achieved. The sacrificial resin mold after successful printing can be dissolved in its own monomer or dissolved in dichloromethane. Due to the self-solubility of the soluble resin, the printing time should not be too long. After removing the resin mold, use anhydrous ethanol to clean the structure to wash off the residual resin, and use a UV lamp for secondary curing to prevent its fine structure from dissolving in its monomer resin residual liquid or ethanol.

[0038] Secondly, after obtaining the sacrificial resin, it needs to be filled. If the structure is designed as a single inlet and single outlet, such as a simple spiral structure, it can be filled using conventional methods such as injection. However, the three-dimensional liquid metal structure obtained by this method can only serve below the melting point and still belongs to a type of liquid processing solid-state molding method.

[0039] In this embodiment, ultrasound is introduced to drive the liquid metal to fill the mold. Ultrasound is used to make the liquid metal produce an excessive oxide film during the filling process to support its structure and achieve liquid service above the melting point. The specific device schematic diagram is shown in FIG. Figure 1 As shown. The sacrificial resin mold 1 only needs to be placed on the acrylic plate 2, and a stable connection with the acrylic plate 2 can be achieved through secondary curing with an ultraviolet lamp. The acrylic plate 2 is connected to the sacrificial resin mold 1 and fixed on a titanium alloy fixture 4 for transmitting ultrasound through bolts 3. After that, ultrasound is applied through an ultrasonic probe 5, and liquid metal can be poured into the channel under the action of ultrasound. Figure 2 The resin mold is filled with ultrasonically driven liquid metal. The liquid metal used is pure Ga (melting point 29.76°C). Figure 3 This is the result of the swelling of the sacrificial resin mold after it was placed in dichloromethane for 4 hours at room temperature (25°C). Figure 4 The figure shows the result of placing the mold in dichloromethane at room temperature for 24 hours and removing it, and the mold is completely dissolved. In this way, a liquid metal solid spiral structure with controllable pitch morphology can be obtained. In this embodiment, the diameter of the spiral is about 250 μm.

[0040] In this embodiment, due to the effect of ultrasound, the liquid metal will produce excessive oxide film during the pouring process. These oxide film structures can help stabilize the liquid metal structure, which allows the liquid metal solid structure prepared by ultrasonic casting to maintain its shape and function normally even above its melting point. Because the amount of oxide film in the liquid metal is difficult to quantitatively characterize, but the increase in liquid metal oxides will affect the viscosity of the liquid metal itself, we studied the effect of 600W ultrasonic power on the viscosity of the liquid metal after 2s and 5s. Figure 5 As shown, it can be seen that the viscosity of the liquid metal increases by about 5% after 2s of ultrasound and by about 20% after 5s. This result shows that ultrasound will produce additional oxides while driving the movement of liquid metal.

[0041] In order to verify the service capability of the ultrasonically driven liquid metal solid spiral in liquid state, the prepared solid liquid metal spiral structure was placed in a 50°C water bath. The results after 5 minutes are as follows: Figure 6 As shown in (a) and 6(b), it can be seen from the results in the figure that the liquid metal only changes the local thickness of the spiral due to its high surface tension, but the structure itself does not collapse, which is different from the liquid metal spiral structure prepared by the traditional injection method. The liquid metal spiral structure prepared by the traditional injection method will collapse quickly after reaching the melting point, and no longer has a three-dimensional structure, such as Figure 6 (c) and 6(d).

[0042] On this basis, we designed two-layer lattice, three-layer lattice and football C 60 The sacrificial mold was filled with the ultrasonic driving method. After the sacrificial mold was dissolved, it was placed in a water bath at 50°C for 5 minutes. The final result is shown in the figure. Figure 7 (a)-7(c) as shown. Similarly, because the two-layer lattice, three-layer lattice and football C 60 The interconnected channels and lack of outlets make it impossible to prepare by traditional injection methods. Although the vacuum method can force liquid metal to infuse the channels, it cannot produce excessive oxide film on the surface of the liquid metal like ultrasonic drive, so that the three-dimensional structure of the liquid metal cannot function normally in an environment above its melting point. Figure 7 The ultrasonic driving method of the present invention can be used to obtain complete liquid metal two-layer lattice, three-layer lattice and football C 60 structure, which further highlights the advantages of ultrasonic drive.

[0043] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for casting liquid metal by ultrasonically driving a soluble resin mold, characterized in that: The steps include: Step S1, using modeling software to perform modeling and slicing according to the three-dimensional shape to be formed, and using a 3D printer to print layer by layer to prepare a soluble, channel-containing sacrificial mold; Step S2, fixing the obtained sacrificial mold on a bottom plate, and then fixing the bottom plate on an ultrasonic fixture, applying ultrasound for more than 2 seconds through an ultrasonic probe, so that the liquid metal is poured into the channel under the action of ultrasound; Step S3, removing the mold and dissolving the sacrificial mold.

2. The method for casting liquid metal by ultrasonically driving a soluble resin mold according to claim 1, characterized in that: Step S1 includes: Step S11, preparing a photocurable resin, wherein the components of the photocurable resin include a resin monomer, a photoinitiator and a photoinhibitor; Step S12, using a 3D printer to print a sacrificial mold.

3. The method for casting liquid metal by ultrasonically driving a soluble resin mold according to claim 2, characterized in that: Step S1 also includes: Step S13, after removing the resin mold, use anhydrous ethanol to wash away the residual resin, and use ultraviolet light for secondary curing.

4. The method for casting liquid metal by ultrasonically driving a soluble resin mold according to claim 2, characterized in that: In step S11, the resin monomer is isobornyl acrylate, the photoinitiator is TPO-L, the mass of the photoinitiator is 0.5% to 5% of the mass of the resin monomer, and the photoinhibitor includes at least one of curcumin and copper phthalocyanine, and the mass of the photoinhibitor is 0.02% to 0.5% of the mass of the resin monomer.

5. The method for casting liquid metal by ultrasonically driving a soluble resin mold according to claim 1, characterized in that: The clamp is made of titanium alloy or aluminum alloy.

6. The method for casting liquid metal by ultrasonically driving a soluble resin mold according to claim 1, characterized in that: In step S2, the ultrasonic power is 400-800W, and the ultrasonic time is 2-5s.

7. The method for casting liquid metal by ultrasonically driving a soluble resin mold according to any one of claims 1 to 6, characterized in that: In step S3, the sacrificial mold is dissolved by water or dichloromethane to obtain a formed liquid metal three-dimensional component.

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