A method of ultrasonically driven filling of a mold of dissolvable resin to cast a liquid metal

Abstract

The application provides a method for casting liquid metal by using an ultrasonic driving filled dissolvable resin mold, comprising the following steps: step S1, preparing a dissolvable sacrificial mold containing channels according to a three-dimensional shape to be formed; step S2, fixing the obtained sacrificial mold on a bottom plate, then fixing the bottom plate on an ultrasonic clamp, and applying ultrasonic waves for more than 2s through an ultrasonic probe to make the liquid metal fill into the channels under the action of the ultrasonic waves; and step S3, removing the mold and dissolving the sacrificial mold. By using the technical scheme of the application, the liquid metal is filled into the channels in the mold by means of the sacrificial resin mold combined with ultrasonic driving, and the three-dimensional structure of the liquid metal itself can be maintained without collapsing due to the melting of the liquid metal because the excess oxide film on the surface of the liquid metal induced by the ultrasonic waves can maintain the three-dimensional structure of the liquid metal itself, even if the sacrificial template is dissolved, and the liquid metal still remains in a liquid state, and the excess oxide film on the surface of the liquid metal can still support the structure without collapsing.

Description

Technical Field

[0001] This invention relates to the field of liquid metal three-dimensional configuration technology, and in particular to a method for casting liquid metal using ultrasonically driven filling of a soluble resin mold. Background Technology

[0002] Currently, most liquid metal patterning methods are geared towards planar processing, with limited application in three-dimensional liquid metal construction. 3D printing technology utilizes a liquid metal oxide film to support its structure; however, this oxide film is relatively thin, only about 5-10 nm thick, and has low mechanical strength (yield stress approximately 0.5 N / m). Therefore, it significantly limits the three-dimensional shape of the liquid metal and prevents arbitrary configuration. Specifically, the printed structures are mostly linear with fine lines (diameter less than 50 μm) and small bend angles. Excessive printing volume of liquid metal or excessive bending angles can lead to oxide film rupture and structural collapse. Therefore, this method makes it very difficult to print large 3D structures using liquid metal printing at room temperature; current needle extrusion and droplet accumulation methods achieve a forming height of approximately 1 cm. Furthermore, literature indicates that the nozzle lift-off speed needs to be controlled between 0.001-0.1 mm / s during liquid metal configuration to ensure that the adhesion energy between the liquid metal and the substrate is less than the oxide film's fracture energy, preventing line breakage during structure construction. For 3D printing combined with a support medium, the properties of the support medium determine the printing quality. The accuracy and resolution of the printed structure are affected by the nozzle diameter, feed flow rate and printing speed. However, it should be noted that the printed liquid metal is in the form of droplets due to its extremely high surface tension, and is not a continuous metal line. In addition, the size of the printed droplets is inconsistent.

[0003] Liquid metal forming methods, whether combined with 3D printing or mold casting, can only produce structural components that function below the melting point of the liquid metal, requiring strict adherence to environmental temperature conditions. Above the melting point, excessive melting of the liquid metal can overwhelm the surface oxide film, ultimately leading to structural collapse. Furthermore, mold casting methods cannot construct complex structures, only producing relatively regular three-dimensional liquid metal structures. This is because complex structures cannot be removed while maintaining structural integrity. Summary of the Invention

[0004] To address the above technical problems, this invention discloses a method for casting liquid metal using ultrasonically driven filling of a soluble resin mold, thus filling the gap in current methods for three-dimensional configuration of pure liquid metal.

[0005] The technical solution adopted by this invention is as follows:

[0006] A method for ultrasonically driven filling of a soluble resin mold to cast liquid metal includes the following steps:

[0007] Step S1: Based on the three-dimensional shape to be formed, modeling software is used to model and slice the shape, and a soluble sacrificial mold containing channels is prepared by printing layer by layer using a 3D printer.

[0008] Step S2: Fix the obtained sacrificial mold on the base plate, then fix the base plate on the ultrasonic fixture, and apply ultrasound for more than 2 seconds through the ultrasonic probe to allow the liquid metal to be injected into the channel under the action of ultrasound.

[0009] Step S3: Remove the mold and dissolve the sacrificial mold.

[0010] This technical solution employs a sacrificial mold combined with ultrasonic infusion. On one hand, liquid metal can be infused into the channels of the sacrificial mold. On the other hand, during the ultrasonic infusion process, the ultrasonic waves drive the liquid metal to move while generating additional oxides, causing an oxide film to form on the surface of the infused liquid metal. This maintains the three-dimensional structure of the liquid metal itself and prevents the structure from collapsing due to the melting of the liquid metal. The resulting liquid metal component remains stable in shape and does not collapse after 5 minutes in a 50°C water bath environment.

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

[0012] Step S11: Prepare the photocurable resin, wherein the components of the photocurable resin include resin monomers, photoinitiators and photoinhibitors;

[0013] Step S12: Print the sacrificial mold using a 3D printer.

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

[0015] Step S13: After removing the resin mold, wash away the residual resin with anhydrous ethanol and perform secondary curing using a UV lamp. This technical solution prevents the fine structure from dissolving in the monomer resin residue 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, and the mass of the photoinitiator is 0.5% to 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% to 0.5% of the mass of the resin monomer. The resin monomer, photoinitiator, and photoinhibitor are mixed evenly 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 shaped liquid metal three-dimensional component.

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

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] Using the technical solution of this invention, a sacrificial resin mold with a complex structure can be photopolymerized using 3D printing equipment. Liquid metal is injected into the mold channels via ultrasonic driving, effectively filling complex, interwoven channels. This ultrasonic-driven filling of liquid metal not only achieves the complex interwoven channel structure that is impossible with injection molding, but also induces an excessive oxide film on the surface of the liquid metal, maintaining its three-dimensional structure and preventing collapse due to melting. Even if the sacrificial template dissolves, the excessive oxide film on its surface can still support the structure and prevent collapse, thus achieving a complex configuration of a pure liquid metal three-dimensional structure—something that traditional injection molding and vacuum methods cannot achieve. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the method for casting liquid metal using ultrasonically driven filling of a soluble resin mold, 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 diagram showing the result of the sacrificial resin mold of this invention swelling in dichloromethane for 4 hours.

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

[0027] Figure 5 The graph shows the effect of 600W ultrasonic power applied for 2s and 5s on the viscosity of liquid metal in the embodiment of the present invention.

[0028] Figure 6These are comparison images of liquid metal solid spirals obtained by ultrasonic driving and injection method according to the present invention. (a) is the result of the liquid metal solid spiral obtained by ultrasonic driving at room temperature, (b) is the result of the liquid metal solid spiral obtained by ultrasonic driving after 5 min in a 50°C water bath, (c) is the result of the liquid metal solid spiral obtained by traditional injection method at room temperature, and (d) is the result of the liquid metal solid spiral obtained by traditional injection method after 5 min in a 50°C water bath.

[0029] Figure 7 This invention employs ultrasonic-driven filling channels to prepare liquid metal solid-state two-layer lattices, three-layer lattices, and soccer ball C. 60 Structural results; where (a) is a two-layer lattice structure, (b) is a three-layer lattice structure, and (c) is a soccer ball C 60 structure.

[0030] The reference numerals in the figures include:

[0031] 1-Sacrificial resin mold, 2-Acrylic sheet, 3-Bolt, 4-Titanium alloy clamp, 5-Ultrasonic probe. Detailed Implementation

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

[0033] To achieve high-precision three-dimensional casting of pure liquid metal, this embodiment discloses a method for ultrasonically driven casting of liquid metal using a mold filled with soluble resin, specifically including:

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

[0035] The first step is to formulate the UV-curable resin. UV-curable resin generally consists of four parts: matrix monomers (which, under the action of a photoinitiator, cure through free radical polymerization to form a cross-linked polymer network), photoinitiator (which generates free radicals under ultraviolet or visible light irradiation, initiating the polymerization reaction of the matrix monomers; its selection and dosage affect the curing speed and depth), photoinhibitor (which controls the rate of polymerization, preventing excessively rapid curing and resulting in uneven material properties or surface defects. Photoinhibitors can capture free radicals and slow down the reaction), and stabilizers (used to improve the storage stability of the UV-curable resin and prevent undesirable polymerization reactions during storage. They can capture low-energy free radicals or react with oxygen, thereby extending the resin's lifespan).

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

[0037] The second step involves printing a sacrificial mold using a 3D printer: Based on the desired 3D shape, modeling software is used to create a model and slice it. The prepared soluble resin is then placed into the resin tank of a high-precision 3D printer for 3D printing. Under the high-precision 3D printer, ultra-microstructures with an XY plane accuracy of 10μm and a Z-axis accuracy of 25μm are achieved. The successfully printed sacrificial resin mold can be dissolved in its own monomer or in dichloromethane. Due to the self-dissolving nature of the soluble resin, the printing time should not be too long. After removing the resin mold, anhydrous ethanol is used to clean the structure and remove residual resin. A secondary curing process using ultraviolet light is then performed to prevent the fine structure from dissolving in the monomer resin residue 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, conventional methods such as injection molding can be used for filling. However, the liquid metal three-dimensional structure obtained by this method can only be used below the melting point and still belongs to the liquid processing solid forming method.

[0039] In this embodiment, an ultrasonically driven liquid metal filling mold is introduced. Ultrasonic waves cause the liquid metal to generate an excess oxide film during the filling process, which supports the structure and enables liquid operation above the melting point. A schematic diagram of the specific device is shown below. 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 a UV lamp. The acrylic plate 2 and the sacrificial resin mold 1 are fixed to the titanium alloy clamp 4 for transmitting ultrasound using bolts 3. Then, ultrasound is applied through the ultrasonic probe 5, and the liquid metal can be injected into the channel under the action of ultrasound. Figure 2 The resin mold was completed using ultrasonically driven liquid metal filling, with pure Ga (melting point 29.76℃) used. Figure 3 This image shows the swelling of a sacrificial resin mold after it has been placed in dichloromethane for 4 hours at room temperature (25°C). Figure 4 The image shows the result after the mold was completely dissolved following placement in dichloromethane at room temperature for 24 hours and removal. This method allows for the acquisition of a liquid metal-solid-state helical structure with controllable pitch morphology; in this embodiment, the helix diameter is approximately 250 μm.

[0040] In this embodiment, the ultrasonic action causes an excessive oxide film to form in the liquid metal during the pouring process. This oxide film structure helps stabilize the liquid metal structure, allowing the solid structure of the liquid metal prepared by ultrasonic casting to maintain its shape and continue normal operation even above its melting point. Since the amount of oxide film in the liquid metal is difficult to quantitatively characterize, but an increase in liquid metal oxides affects its viscosity, we investigated the effect of 600W ultrasonic power on the viscosity of the liquid metal after 2 seconds and 5 seconds. Figure 5 As shown, the viscosity of the liquid metal increases by about 5% after 2 seconds of ultrasound and by about 20% after 5 seconds. This result indicates that ultrasound generates additional oxides while driving the movement of the liquid metal.

[0041] To verify the operational capability of the ultrasonically driven liquid metal solid spiral in a 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), the results in the figures show that the liquid metal only causes a local change in the thickness of the spiral due to its high surface tension, but the structure itself does not collapse. This is different from the liquid metal spiral structure prepared using the traditional injection method. The liquid metal spiral structure prepared by the traditional injection method collapses rapidly after reaching its melting point, thus losing its three-dimensional structure, as shown in (a) and (b). Figure 6 As shown in (c) and 6(d).

[0042] Based on this, we designed two-layer lattices, three-layer lattices, and soccer ball C-type crystals respectively. 60 The mold for the structure was filled using the ultrasonic driving method described above. After the sacrificial mold had completely dissolved, it was placed in a water bath at 50°C for 5 minutes. The final result is shown in the figure below. Figure 7 As shown in (a)-7(c). Similarly, because of the two-layer lattice, the three-layer lattice, and the soccer ball C 60 The interconnected channels and lack of an outlet in the structure prevent it from being fabricated using traditional injection methods. While vacuum methods can force liquid metal into the channels, they cannot induce an excessive oxide film on the surface of the liquid metal like ultrasonically driven methods. Consequently, the three-dimensional structure of the liquid metal cannot function properly above its melting point. Figure 7 Using the ultrasonic driving method of this invention, complete liquid metal two-layer lattices, three-layer lattices, and soccer ball C-type crystals can be obtained. 60 This structure further highlights the advantages of ultrasonic actuation.

[0043] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method of ultrasonic actuated, resin infused, dissolvable mold casting of liquid metal, characterized by: The method comprises the following steps: Step S1, modeling and slicing are performed according to a three-dimensional shape to be formed by using modeling software, and a soluble sacrificial mold containing channels is prepared by layer-by-layer printing by using a 3D printer; Step S2, the obtained sacrificial mold is fixed on a bottom plate, then the bottom plate is fixed on an ultrasonic clamp, and ultrasonic waves are applied by an ultrasonic probe for more than 2s, so that liquid metal is perfused into the channels under the action of the ultrasonic waves; the ultrasonic power is 400-800W, the ultrasonic time is 2-5s, and the liquid metal is Ga-based liquid metal; Step S3, the mold is removed, the sacrificial mold is dissolved by using water or dichloromethane, and a formed three-dimensional liquid metal component is obtained; Step S1 comprises: Step S11, preparing a photocuring resin, wherein the components of the photocuring resin comprise resin monomers, a photoinitiator and a light inhibitor; in Step S11, the resin monomers are isobornyl acrylate, the photoinitiator is TPO-L, the mass of the photoinitiator is 0.5-5% of the mass of the resin monomers, and the light inhibitor comprises at least one of curcumin and copper phthalocyanine, and the mass of the light inhibitor is 0.02%-0.5% of the mass of the resin monomers; Step S12, printing the sacrificial mold by using a 3D printer.

2. The method of claim 1, wherein the method further comprises: Step S1 further comprises: Step S13, after the resin mold is removed, residual resin is washed away by using anhydrous ethanol, and secondary curing is performed by using an ultraviolet lamp.

3. The method of claim 1, wherein the method further comprises: The clamp is made of titanium alloy or aluminum alloy.

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