4D printing method for a magnetic composite material

Abstract

The present invention discloses a 4D printing method for a magnetic composite material, which specifically includes: mixing magnetized particles, a photocurable monomer, a photosensitive auxiliary agent, and a dispersant to obtain a printing slurry; putting the printing slurry into a digital light processing 3D printer and dividing it into regions according to the magnetization structure; applying a unidirectional and uniform orientation magnetic field to the regions with the same magnetization structure and exposing and curing the regions; applying a unidirectional and uniform magnetization magnetic field to the cured printing regions; repeating the steps of orientation exposure and magnetization for the printing slurry in the remaining regions; printing layer by layer to form a magnetic composite blank; applying mechanical force to obtain a magnetic composite material; compared with the prior art, the present invention applies an orientation magnetic field and a magnetization magnetic field to the printing slurry in sequence while performing digital light processing 3D printing on the printing slurry, which can enable the magnetized particles in the obtained magnetic composite material to be orderly arranged along the designed magnetization direction, obtaining a relatively high orientation consistency, thereby forming a magnetization structure with spatial magnetic anisotropy.

Description

Technical Field

[0001] The present invention relates to the technical field of 4D printing, and more particularly, to a 4D printing method for a magnetic composite material. Background Art

[0002] During the process of 3D printing, an auxiliary magnetic field is used to magnetically orient the magnetized particles in the printing slurry, so as to obtain a flexible topological magnetized functional device whose shape, properties, and functions can be controllably changed under external stimuli (such as magnetic fields, heat energy, pressure, etc.), which can be classified into the category of 4D printing. The connection between topology and material physics and material properties is becoming closer and closer. It can be said that the concept of topology is being applied to more and more disciplinary fields, and the contribution of topology is found in more and more materials. The flexible topological magnetized functional device is composed of magnetized particles dispersed in an elastic matrix. Its topological magnetization structure refers to the magnetically anisotropic magnetization structure formed by arranging the magnetized particles along the designed magnetization direction in the elastic matrix in an orderly manner. During the 3D printing and forming manufacturing process, under the action of the auxiliary magnetic field, the magnetized particles in the elastic matrix are arranged in a regionalized space, and the magnetic pole orientation is programmed in an orderly manner in the region. Applying a mechanical force to the 3D printed flexible topological magnetized functional device causes the device to deform to generate a change in the surrounding magnetic field, generating a "force-magnetic" conversion effect, thereby completing the 4D printing of the flexible topological magnetized functional device. The flexible topological functional device can be used in emerging flexible electronic device fields, such as magnetoresponsive soft robots, magnetic pressure sensors, etc.

[0003] However, the existing 3D printing processes and printing materials need to be improved urgently. For the printing process of applying an auxiliary magnetic field to the printing slurry first and then curing, and the magnetized particles agglomerate due to mutual attraction, which affects the photocuring process of the slurry, resulting in a relatively low orientation consistency of the magnetized particles in the magnetization direction (about 64%), and further leading to a low magnetization intensity of the flexible topological magnetized functional device and a low "force-magnetic" conversion efficiency. Summary of the Invention

[0004] The object of the present invention is to provide a 4D printing method for a magnetic composite material, which applies an orientation magnetic field and a magnetization magnetic field to the printing slurry in sequence while digitally light-processing the 3D printing slurry, so that the magnetized particles in the obtained magnetic composite material are arranged in an orderly manner along the designed magnetization direction, obtaining a relatively high orientation consistency, thereby forming a spatially magnetically anisotropic magnetization structure.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows: A 4D printing method for a magnetic composite material, the 4D printing method specifically includes the following steps,

[0006] S1. Prepare the printing slurry: Mix magnetized particles, a photocurable monomer, a photosensitive auxiliary agent, and a dispersant to obtain the printing slurry;

[0007] S2. Sub-region: Put the printing slurry into a digital light processing 3D printer and divide the printing slurry according to the magnetization structure;

[0008] S3. Orientation curing: Apply a uniform and co-directional orientation magnetic field to the regions with the same magnetization structure in step S2, so that the magnetization particles in this region undergo topological arrangement and flipping, and then expose and cure this region;

[0009] S4. Magnetization: Apply a uniform and co-directional magnetization magnetic field to the cured printing region in step S3, so that the domain wall displacement and magnetic domain rotation parallel to the magnetization magnetic field occur inside the magnetization particles that are not 100% oriented along the magnetization direction in the region;

[0010] S5. Single-layer printing: Repeat steps S3 and S4 for the printing slurry in the remaining regions until the orientation, curing, and magnetization of all regions in a single layer are completed;

[0011] S6. Layer-by-layer printing: Repeat steps S2 - S5 to print layer by layer to form a magnetic composite blank;

[0012] S7. Force-magnetic conversion: Apply mechanical force to the magnetic composite blank obtained in step S6, so that the magnetic composite blank deforms to generate a change in the surrounding magnetic field, and a magnetic composite material is obtained.

[0013] In the present invention, an orientation magnetic field and a magnetization magnetic field are sequentially applied to the printing slurry while performing digital light processing 3D printing of the slurry. Among them, the applied orientation magnetic field causes the magnetization particles in the printing slurry to undergo topological arrangement and flipping, and the applied in-situ magnetization magnetic field can cause domain wall displacement and magnetic domain rotation parallel to the magnetization magnetic field inside the magnetization particles that are not 100% oriented along the magnetization direction and other technical magnetization processes. Finally, mechanical force is applied to the flexible topological magnetization functional device, and the device deforms to generate a change in the surrounding magnetic field, generating a "force-magnetic" conversion effect.

[0014] Further, in step S1, the magnetization particles are selected from one or more of hard magnetic neodymium iron boron, hard magnetic samarium iron nitride, and hard magnetic ferrite.

[0015] Further, in step S1, the magnetization particles contain at least two magnetic domains.

[0016] Further, in step S1, the magnetization particles are rod-shaped particles. When forming the topological magnetization functional device to be manufactured, compared with irregularly shaped magnetization particles, rod-shaped particles are more likely to flip and arrange in space under the action of the orientation magnetic field.

[0017] Further, in step S1, the aspect ratio of the magnetization particles is greater than 1.

[0018] Further, in step S1, the surface of the magnetization particles is coated with an isolation layer.

[0019] Further, the material of the isolation layer is stearic acid or resin. Precoating the surface with stearic acid or resin can not only reduce the agglomeration effect between the magnetic particles, but also reduce the absorption of ultraviolet light by the dark magnetic particles in the digital light processing (DLP) 3D printing technology.

[0020] Further, in step S2, when applying the orientation magnetic field, the specified area is synchronously selectively exposed and cured. After the curing is completed, the orientation magnetic field is stopped first, and then the magnetization magnetic field is applied. During the printing process, when applying the orientation magnetic field to the printing slurry, synchronous regional exposure curing is performed on it, and after curing, the magnetization magnetic field is applied to obtain a flexible topological magnetization functional device.

[0021] Further, both the orientation magnetic field and the magnetization magnetic field are provided by 1, 1 pair or multiple pairs of inductance coils.

[0022] Further, in step S2, the magnetic induction intensity of the orientation magnetic field is set to B1, and its range is B1≥250mT.

[0023] Further, in step S2, the magnetic induction intensity of the magnetization magnetic field is set to B2, and its range is 250mT<B2≤1.5T.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] First, the present invention applies the orientation magnetic field and the magnetization magnetic field to the printing slurry in sequence while performing digital light processing 3D printing on the printing slurry, which can cause technical magnetization processes such as domain wall displacement and magnetic domain rotation parallel to the magnetization magnetic field inside the magnetic particles that are not 100% oriented along the magnetization direction, enabling the magnetic particles in the obtained magnetic composite material to be orderly arranged along the designed magnetization direction, obtaining a high orientation consistency, and thus forming a magnetically anisotropic magnetization structure in space.

[0026] Second, the present invention improves the orientation consistency of the magnetic particles and the magnetization intensity of the topological magnetization structure elastomer by regulating the physical properties of the printing slurry such as the type, shape, concentration, and surface pretreatment state of the magnetic particles, as well as adjusting the magnetization and curing parameters of the existing magnetic field-assisted 3D printing technology, and obtains a flexible topological magnetization functional device that can efficiently perform "force-magnetism" conversion;

[0027] Third, the magnetic particles in each region of the magnetic composite material prepared by the present invention are orderly arranged in space, and the spatial magnetic pole orientations of the magnetic particles in each region are different, the corresponding magnetization directions of each region are also different, and at the same time, the magnetization magnitudes and directions in each region are different, and the overall surface magnetic flux distribution can be regulated. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1It is the implementation schematic diagram of steps (b)-(f) in Embodiment 2 of the present invention;

[0029] Figure 2 It is the working schematic diagram of the 4D printing platform of the present invention;

[0030] Figure 3 It is the control schematic diagram of the orientation magnetic field and the magnetization magnetic field during the preparation process of the present invention. Detailed implementation manners

[0031] To make the above objects, features and advantages of the present invention more obvious and understandable, the following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings.

[0032] Embodiment 1

[0033] As Figure 1 shown, in this embodiment, the interior of the magnetic composite material is divided into five regions i-v according to the design requirements. Among them, the internal magnetization structures of regions ⅰ, ⅲ, and ⅴ are the same, and the internal magnetization structures of regions ⅱ and ⅳ are the same. The specific preparation process of this magnetic composite material is as follows:

[0034] (a) Prepare the printing slurry: Mix the magnetized particles, photocurable monomers, photosensitive additives, and dispersants to obtain the printing slurry, and put the printing slurry into a digital light processing 3D printer; the magnetized particles include hard magnetic samarium iron nitride and hard magnetic ferrite, and both contain three magnetic domains, and the magnetized particles are rod-shaped particles with an aspect ratio of 4. The surface of the magnetized particles is coated with an isolation layer, and the material of the isolation layer is resin;

[0035] (b) Divide the pre-curing area in the digital light processing 3D printer into regions ⅰ-ⅴ according to different magnetization structures;

[0036] (c) Apply an upward orientation magnetic field 1 to regions ⅱ and ⅳ, so that the magnetized particles undergo spatial flipping and alignment along the direction of the orientation magnetic field, and at the same time expose and cure regions ⅱ and ⅳ to obtain regions ⅱ and ⅳ with fixed magnetization directions;

[0037] (d) Apply an upward magnetization magnetic field 1 to regions ⅱ and ⅳ, so that technical magnetization processes such as domain wall displacement and magnetic domain rotation parallel to the magnetization magnetic field occur inside the magnetized particles that are not 100% oriented along the magnetization direction, and obtain regions ⅱ and ⅳ with high magnetization intensity along the direction of the auxiliary magnetic field;

[0038] (e) Apply a leftward orientation magnetic field 2 to regions ⅰ, ⅲ, and ⅴ, so that the magnetized particles undergo spatial flipping and alignment along the direction of the orientation magnetic field, and at the same time expose and cure regions ⅰ, ⅲ, and ⅴ to obtain regions ⅰ, ⅲ, and ⅴ with fixed magnetization directions;

[0039] (f) Apply a magnetizing magnetic field 2 in the left direction to regions ⅰ, ⅲ, and ⅴ, causing technical magnetization processes such as domain wall displacement and magnetic domain rotation parallel to the magnetizing magnetic field inside the magnetized particles that are not 100% oriented along the magnetization direction, to obtain regions ⅰ, ⅲ, and ⅴ with high magnetization intensity along the direction of the auxiliary magnetic field.

[0040] (g) According to the topological magnetization structure, regulate the auxiliary magnetic field and the curing process, and repeat the operations in (a)-(f) to stack and print layer by layer to achieve the preparation of the magnetic composite blank.

[0041] (h) Force-magnetic conversion: Apply mechanical force to the magnetic composite blank obtained in step (g) to cause the magnetic composite blank to deform to generate a change in the surrounding magnetic field, obtaining the magnetic composite.

[0042] In this embodiment, the magnetic induction intensity of the orientation magnetic field is set to B1, and B1 is 150 mT.

[0043] In this embodiment, the magnetic induction intensity of the magnetizing magnetic field is set to B2, and B2 is 1 T.

[0044] In the present invention, when the magnetization structures in the magnetic composites to be prepared are the same, the sub-region step can be omitted, and the orientation, curing, and magnetizing steps can be directly carried out.

[0045] As Figure 2 shown, during the preparation process of the present invention, after each layer is cured, the scraping plate will move to ensure that the thick material is evenly smeared on the printing plane, and printing with a high magnetic powder content (>15 vol.%) can be achieved.

[0046] As Figure 3 shown, during the preparation process of the present invention, the Z-axis lifting motor signal is read and processed by the controller (Arduino). When the Z-axis motor works (the platform rises or falls), the power supply of the electromagnet is disconnected; when the Z-axis motor stops (ready for photocuring), the power supply of the inductance coil is connected, and the magnetic field size of the inductance coil is adjusted by regulating the current size to apply the orientation magnetic field and the magnetizing magnetic field to the formed manufacturing part.

[0047] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. A 4D printing method for a magnetic composite material, characterized in that The specific steps of the 4D printing method are as follows: S1. Prepare the printing slurry: Mix magnetic particles, photocurable monomers, photosensitive additives, and dispersants to obtain the printing slurry; S2. Divide into regions: Put the printing slurry into a digital light processing 3D printer and divide the printing slurry according to the magnetization structure; S3. Orientation curing: Apply a uniform and co-directional orientation magnetic field to the regions with the same magnetization structure in step S2, so that the magnetic particles in this region undergo topological arrangement and flipping, and then expose and cure this region; S4. Magnetization: Apply a uniform and co-directional magnetization magnetic field to the cured printing region in step S3, so that the domain wall displacement and magnetic domain rotation parallel to the magnetization magnetic field occur inside the magnetic particles that are not 100% oriented along the magnetization direction in the region; S5. Single-layer printing: Repeat steps S3 and S4 for the printing slurry in the remaining regions until the orientation, curing, and magnetization of all regions in a single layer are completed; S6. Layer-by-layer printing: Repeat steps S2 - S5 to print layer by layer to form a magnetic composite blank; S7. Force-magnetic conversion: Apply mechanical force to the magnetic composite blank obtained in step S6 to cause the magnetic composite blank to deform to generate a change in the surrounding magnetic field, thereby obtaining a magnetic composite material.

2. The 4D printing method of the magnetic composite material according to claim 1, wherein In step S1, the magnetic particles are selected from one or more of hard magnetic NdFeB, hard magnetic SmFeN, and hard magnetic ferrite.

3. The 4D printing method of the magnetic composite material according to claim 2, characterized in that, In step S1, the magnetic particles contain at least two magnetic domains.

4. The 4D printing method of the magnetic composite material according to claim 1, characterized in that, In step S1, the magnetic particles are rod-shaped particles.

5. The 4D printing method of the magnetic composite material according to claim 4, characterized in that, In step S1, the aspect ratio of the magnetic particles is greater than 1.

6. The 4D printing method of the magnetic composite material according to claim 1, characterized in that, In step S1, the surface of the magnetic particles is coated with an isolation layer.

7. The 4D printing method of the magnetic composite material according to claim 6, characterized in that, The material of the isolation layer is stearic acid or resin.

8. The 4D printing method of the magnetic composite material according to claim 1, characterized in that, In step S3, the magnetic induction intensity of the orientation magnetic field is set to B1, and its range is B1 ≤ 250 mT.

9. The 4D printing method of the magnetic composite material according to claim 8, wherein In step S4, the magnetic induction intensity of the magnetization magnetic field is set to B2, and its range is 250 mT < B2 ≤ 1.5 T.

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