Resistance thermal additive manufacturing method and device for large-size nano nickel component

Abstract

The invention discloses a resistance thermal additive manufacturing method and device for a large-size nano nickel component, and belongs to the technical field of nano material preparation, the manufacturing method comprises the steps that nano nickel powder is laid on the surface of a substrate to form a nano nickel powder layer or the nano nickel powder is pressed into a nano nickel powder plate to be placed on the surface of the substrate; the nano nickel powder layer or the nano nickel powder plate is subjected to resistance thermal additive manufacturing, gaps of the nano nickel powder and the contact area of the nano nickel powder and the substrate are selectively melted through the resistance thermal effect to form metallurgical bonding, meanwhile, the nano structure in the nano nickel powder is reserved, and a single-layer nano nickel component is obtained; and the single-layer nano-nickel component is subjected to multi-layer resistance thermal additive manufacturing, and the large-size nano-nickel component is manufactured. According to the method, the problem that the performance of the prepared component is remarkably reduced due to the fact that a traditional laser / electric arc melting additive manufacturing technology destroys the nano structure is fundamentally solved, and the centimeter / decimeter-level nano nickel component can be prepared at low cost.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation technology, specifically relating to a method and apparatus for resistive thermal additive manufacturing of large-size nano-nickel components. Background Technology

[0002] Nano-nickel refers to nickel particles or structures with diameters ranging from 1 to 100 nanometers. Nickel materials of this size possess physicochemical properties completely different from traditional macroscopic nickel. Due to the significantly increased surface atomic ratio, nano-nickel exhibits higher reactivity, lower melting point, stronger magnetism, and conductivity. Nano-nickel components are structural parts with specific functions, made from nanoscale nickel materials as the core through specific fabrication processes. They have outstanding advantages in areas such as improved wear resistance, efficient battery catalysis, efficient electron transport in electronic devices, and high-performance corrosion-resistant materials.

[0003] The production and preparation of nanopowders are relatively mature, and their production cost is also relatively low. However, transforming nanopowders into large-sized nanomaterial components with nanocrystalline structures is extremely difficult. Traditional powder-laying (feeding) printing or powder-laying (feeding) additive manufacturing technologies are widely used in the additive manufacturing field. By feeding and laying powder in conjunction with heat sources such as electric arcs and lasers, powder can be melted and solidified to achieve metallurgical bonding. However, this technology generally requires melting the powder to form a molten pool and then resolidifying it. The powder used has a micron-sized structure. Even when using nanopowders, the nanopowder will still be melted and resolidified, destroying its nanostructure (10~100nm). The resolidified structure grows to a micron-sized size (1~500μm). Compared to materials with nanocrystalline structures, the tensile strength decreases from 1~30GPa to 0.1~0.8GPa, and the ductility and toughness also decrease significantly. Therefore, components made using nanopowders or micron-sized powders generally do not show significant differences in performance, failing to leverage the advantages of nanopowders. Existing additive manufacturing technologies such as electric arc and laser powder feeding / laying will melt and destroy the nanocrystalline structure of nanopowder, resulting in a significant reduction in material strength and other properties, making it impossible to prepare nanocrystalline structure components based on nanopowder.

[0004] Currently, physical vapor deposition (PVD) and chemical vapor deposition (CVD) are the main technologies for preparing nanomaterials. However, PVD and CVD are both thin-film preparation processes, which can only produce thin-film nanocrystalline nickel components a few micrometers or tens of micrometers in size, and the preparation cost is relatively high, which greatly limits the widespread industrial application of nanomaterials. Currently, there are no reports on technologies for preparing large-size nanocrystalline nickel components at the centimeter or even decimeter scale using nano-nickel powder and resistance thermal additive manufacturing technology. This technology has significant advantages in the low-cost preparation of large-size nanocrystalline nickel components. Therefore, this invention urgently needs to propose a method and apparatus for the resistance thermal additive manufacturing of large-size nanocrystalline nickel components to solve the above problems. Summary of the Invention

[0005] To address the technical problems raised in the background art, the main objective of this invention is to provide a resistance heating additive manufacturing method and apparatus for large-size nano-nickel components. By utilizing the resistance heating effect, metallurgical bonding is formed between powder particles and between powder and matrix, while preserving the nanostructure inside the nano-nickel powder. Compared with the existing technology for preparing metal components, the grain size is reduced to the nanoscale, the tensile strength can be increased by 3 to 15 times, and the toughness is increased by more than 20%.

[0006] To achieve the above objectives, one aspect of the present invention provides a method for resistive thermal additive manufacturing of large-size nano-nickel components, comprising the following steps: Step S1, providing nano-nickel powder; Step S2: The nano-nickel powder is deposited on the substrate surface to form a nano-nickel powder layer or the nano-nickel powder is pressed into a nano-nickel powder plate and placed on the substrate surface. Step S3: The nano-nickel powder layer or the nano-nickel powder plate is subjected to resistance heating additive manufacturing. The resistance heating effect is used to selectively melt the gaps between the nano-nickel powder and the contact area between the nano-nickel powder and the substrate to form a metallurgical bond, while retaining the nanostructure inside the nano-nickel powder, to obtain a single-layer nano-nickel component. Step S4: Using the single-layer nickel nanostructure as a new substrate, repeat steps S2 and S3 to perform multilayer resistance thermal additive manufacturing until the desired large-size nickel nanostructure is obtained.

[0007] Further, in step S2, the nano-nickel powder layer is laid using an electrostatic powder laying process, which specifically includes the following steps: nano-nickel powder is quantitatively conveyed through a powder feeding funnel, distributed to the substrate surface by a powder feeding roller, and then the nano-nickel powder is vibrated, leveled and initially compacted using a non-contact powder laying electrode. Finally, multi-stage rollers are used for further compaction to obtain the nano-nickel powder layer.

[0008] Further, in step S2, the nano-nickel powder is pressed into a nano-nickel powder plate under a pressure of 0.1~3 GPa.

[0009] Further, in step S3, the nano-nickel powder layer is subjected to resistive thermal additive manufacturing, specifically including: An electric electrode with a roller-type pressure structure is applied to the upper surface of the nano-nickel powder layer to apply current and pressure. The substrate on the lower surface serves as the other electric electrode, forming a current loop with the electric electrode on the upper surface. The resistance heating effect generated in the current loop is used to selectively melt the gaps between the nano-nickel powder and the contact area between the nano-nickel powder and the substrate to form a metallurgical bond, while retaining the nanostructure inside the nano-nickel powder, thus obtaining a single-layer nano-nickel component.

[0010] Furthermore, the parameters for applying power and pressure include: voltage of 5~10V, current of 2000~7000A, load of 1~100MPa, single rolling width of 1~20mm, and rolling speed of 2~6mm / s.

[0011] Further, in step S3, the nano-nickel powder plate is subjected to resistance thermal additive manufacturing, specifically including: A planar electrode is applied to the upper and lower surfaces of a nano-nickel powder plate to conduct an electric current operation. The electrode on the lower surface and the electrode on the upper surface form a current loop. The resistive heating effect generated in the current loop selectively melts the gaps between the nano-nickel powder and the contact area between the nano-nickel powder and the substrate to form a metallurgical bond, while retaining the nanostructure inside the nano-nickel powder, thus obtaining a single-layer nano-nickel component.

[0012] Furthermore, the voltage parameters for the power-on operation are 2~10V, the current parameters are 2000~7000A, and the load is 0~100MPa.

[0013] Furthermore, in step S1, the particle size of the nano-nickel powder is 10~50nm.

[0014] Further, in step S1, the nano-nickel powder is prepared by the following steps: ball milling micron-sized nickel powder, with a ball-to-material ratio of 15~20:1, a ball milling speed of 500~800 rpm, and a ball milling time of 6~15 h, and the nano-nickel powder is obtained after the ball milling is completed.

[0015] In another aspect, the present invention provides a large-size nano-nickel component, which is prepared by the aforementioned resistance thermal additive manufacturing method.

[0016] In another aspect, the present invention provides a resistance thermal additive manufacturing apparatus for large-size nano-nickel components, for implementing the aforementioned resistance thermal additive manufacturing method, wherein the additive manufacturing apparatus includes an electrostatic powder spreading unit, a powder compaction unit, and an energized pressurization unit. The electrostatic powder spreading unit includes an insulating support, and a powder feeding funnel, a powder feeding roller, an insulator, and a non-contact powder spreading electrode disposed on the insulating support. The insulator is located in front of the non-contact powder spreading electrode and is bonded to the non-contact powder spreading electrode. The powder compaction unit includes a multi-stage roller disposed on the insulating support, and the multi-stage roller is located behind the non-contact powder spreading electrode; The energized pressurizing unit includes an energized electrode configured as a roller-type pressurizing structure, which is located behind the multi-stage rollers.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention utilizes the resistive heating effect in additive manufacturing of nano-nickel components. It selectively melts only areas with high resistance, such as gaps and contact points between nanoparticles, achieving metallurgical bonding between powder particles and between the powder and the substrate. Simultaneously, it perfectly preserves the nanocrystalline structure within the nanoparticles, fundamentally solving the problem of traditional additive manufacturing techniques, such as laser / arc melting, damaging the nanostructure and leading to a significant reduction in component performance. Compared to PVD and CVD processes, it overcomes the limitations of these processes in producing large-size nanocrystalline nickel components and their high manufacturing costs.

[0018] 2. The nickel component of the present invention has a microstructure of nanoscale size, metallurgical bonding between nanocrystals, tensile strength of GPa level, and component size of centimeters / decimeter level, which is a significant improvement in component size and overall performance compared with the prior art.

[0019] 3. To address the challenge of achieving integrated, continuous, and efficient operation in the powder feeding, spreading, and forming processes of existing arc thermal additive manufacturing equipment for large-size, low-cost nano-nickel components, this invention provides a resistance thermal additive manufacturing device for large-size nano-nickel components. By integrating an energized electrode with a roller-type pressure structure behind a non-contact electrostatic powder spreading device, online powder feeding, spreading, powder leveling, multi-stage compaction, and continuous additive manufacturing are achieved. This successfully solves the problem of the inflexible and continuous integrated operation of the nano-nickel powder resistance thermal additive manufacturing process, enabling low-cost, high-efficiency, and flexible preparation of large-size nano-nickel components. Attached Figure Description

[0020] Figure 1 A schematic diagram illustrating the technical principle of the resistive thermal additive manufacturing method for large-size nano-nickel components of the present invention is shown. Figure 2 This diagram illustrates the technical principle of existing laser / arc additive manufacturing methods. Figure 3 A schematic diagram of the structure of the resistance thermal additive manufacturing apparatus for large-size nano-nickel components of the present invention is shown. Figure 4 A schematic flowchart of the process combining powder compression molding and flat-plate resistance thermoforming in Embodiment 2 of the present invention is shown. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range. The invention will now be described in detail with reference to embodiments.

[0022] To achieve the above objectives, a first aspect of the present invention provides a method for resistive thermal additive manufacturing of large-size nano-nickel components, comprising the following steps: Step S1, providing nano-nickel powder; Step S2: The nano-nickel powder is deposited on the substrate surface to form a nano-nickel powder layer or the nano-nickel powder is pressed into a nano-nickel powder plate and placed on the substrate surface. Step S3: The nano-nickel powder layer or the nano-nickel powder plate is subjected to resistance heating additive manufacturing. The resistance heating effect is used to selectively melt the gaps between the nano-nickel powder and the contact area between the nano-nickel powder and the substrate to form a metallurgical bond, while retaining the nanostructure inside the nano-nickel powder, to obtain a single-layer nano-nickel component. Step S4: Using the single-layer nickel nanostructure as a new substrate, repeat steps S2 and S3 to perform multilayer resistance thermal additive manufacturing until the desired large-size nickel nanostructure is obtained.

[0023] This invention innovatively proposes a fabrication process for large-size, low-cost, and high-performance nano-nickel components. This process involves applying electricity or pressure to nano-nickel powder, causing melting only at the gaps and contact points of the nano-powder due to high resistance heat. This results in metallurgical bonding between the powder particles and between the powder and the substrate, while the nano-structure inside the nano-powder remains intact without grain growth. This achieves the goal of preserving the microstructure of the nano-nickel powder. Large-size nano-nickel components can be fabricated by multilayer resistance heat additive manufacturing of the nano-powder, with dimensions reaching the centimeter and decimeter scale.

[0024] The specific principles of this invention are as follows: Figure 1 Specifically, during the energizing process, the resistance is relatively high at the gaps between the powder particles and at the contact points between the powder and the substrate, resulting in significant resistive heat. This causes the material in these areas to melt rapidly. Once the material in these areas melts, a metallurgical bond is formed, causing the resistance to drop rapidly and reducing the resistive heat generated. Meanwhile, the interior of the powder, which is already metallurgically bonded, has lower resistance and therefore generates less resistive heat under the same current. Consequently, the interior of the nanoparticles does not melt and retains its nanostructure. Therefore, this resistive thermal additive manufacturing method can be used to fabricate large-sized nanocrystalline components.

[0025] The principle of existing arc / laser additive manufacturing methods for fabricating metal components is based on... Figure 2The electric arc / laser additive manufacturing method uses micron-sized powder, not nanoparticles. Specifically, this technology uses an electric arc, laser, or other physical field as a heat source. Its core requirement is to melt the powder as a whole, form a molten pool, and then solidify it to form a metallurgical bond to obtain a metal component. This destroys the original powder structure, failing to retain its performance characteristics and thus failing to leverage the high-performance features of nanoparticles. Therefore, low-cost micron-sized powder is generally used. Even with nanoparticle structures, nano-metal components cannot be obtained. Because the powder is melted and then re-solidified, its microstructure size increases to the micron level (e.g., the initial 1-50 nm may increase to 1-500 μm). Consequently, compared to materials with nanocrystalline structures, its tensile strength decreases from 1-30 GPa to 0.1-0.8 GPa, and its toughness is also worse.

[0026] In summary, compared to PVD and CVD processes, the fabrication process of this invention solves the problems of these processes being unable to produce large-size nanocrystalline nickel components and having high fabrication costs. This invention expands the fabrication size of nano-nickel from the micrometer level to the centimeter and decimeter level. Compared to existing arc / laser additive manufacturing methods, it solves the problem that these technologies melt nanopowders and destroy their nanostructure, leading to a significant reduction in the performance of the fabricated components. Compared to existing technologies, the grain size of metal components is reduced to the nanometer level, tensile strength is increased by 3 to 15 times, and toughness is improved by more than 20%.

[0027] In a preferred embodiment of the present invention, large-size nano-nickel components are prepared using an electrostatic powder-laying process and a rolling resistance thermal additive manufacturing process. The electrostatic powder-laying process specifically includes the following steps: quantitatively feeding nano-nickel powder through a powder feeding funnel, distributing it onto the substrate surface via a powder feeding roller, then using a non-contact powder-laying electrode to vibrate, level, and initially compact the nano-nickel powder, and finally using a multi-stage roller for further compaction to obtain the nano-nickel powder layer. This method allows for online powder feeding, laying, and compaction, offering the advantage of continuous integration and yielding a high-density nano-nickel powder layer, facilitating subsequent resistance thermal additive manufacturing and ultimately contributing to the production of high-performance large-size nano-nickel components. Preferably, the powder travel speed during the electrostatic powder-laying process is 0.05~5 m / min, more preferably 0.1~2 m / min, and the operating voltage is 5~70 kV, more preferably 0.5~1 m / min.

[0028] In a preferred embodiment of the present invention, in step S3, the nano-nickel powder layer is subjected to resistance thermal additive manufacturing using a rolling resistance thermal additive manufacturing process. Specifically, this includes: applying an energized electrode with a roller-type pressure structure to the upper surface of the nano-nickel powder layer for energization and pressure application; the substrate on the lower surface serves as the other energized electrode, forming a current loop with the energized electrode on the upper surface; and utilizing the resistance thermal effect generated in the current loop to selectively melt the gaps between the nano-nickel powder particles and the contact area between the nano-nickel powder particles and the substrate to form a metallurgical bond, while preserving the internal nanostructure of the nano-nickel powder particles, resulting in a single-layer nano-nickel component. The roller-type pressure structure energized electrode used in this invention ensures the flatness and density of the powder layer, achieving high strength in the nano-nickel component.

[0029] Furthermore, the parameters for the energized pressurization include: a voltage of 5-10V, a current of 2000-7000A, preferably 3000-500A, a load of 1-100MPa, preferably 20-80MPa, a single rolling width of 1-20mm, and a rolling speed of 2-6mm / s. By precisely controlling the voltage and current parameters under the above conditions, suitable resistance heat can be ensured, allowing selective melting of the gaps in the nano-nickel powder and the contact area with the energized electrode, forming a metallurgical bond while preserving the nanostructure within the nano-nickel powder. By precisely controlling the load, rolling width, and rolling speed under the above conditions, a large amount of Joule heat can be rapidly generated while ensuring the powder is fully compacted. 2 R rapidly melts nanopowders, balancing molding quality, efficiency, and the nanocrystalline structure of the final component.

[0030] In an optional embodiment of the present invention, the energized electrode of the roll-type pressure structure can be, for example, a modified roll welding equipment, wherein the rolling surface of the roll welding equipment is modified into a roll-type energized pressure structure as the energized electrode for the energized pressure operation. The flat plate energized electrode can, for example, be a planar graphite electrode.

[0031] Considering that contact pressure and contact current are necessary to prepare nano-nickel components when performing resistance thermal additive manufacturing on nano-nickel powder layers, but contact will cause displacement of the previously laid powder, resulting in uneven molding, insufficient density, or failure to form. In a preferred embodiment of the present invention, nano-nickel powder can be pre-pressed into nano-nickel powder plates for flat-plate resistance thermal additive manufacturing, specifically including: Under a pressure of 0.1~3 GPa, nano-nickel powder is first pressed into nano-nickel powder plates using a mold. The pressed nano-nickel powder plates are then placed on the surface of a substrate, and then the nano-nickel powder plates on the substrate are placed between flat electroplated electrodes for energization. The voltage parameters for energization are 2~10V, and the current parameters are 2000~7000A (preferably 3000~5000A). The resistance heating effect generated in the current loop formed by the lower and upper surface electroplated electrodes selectively melts the gaps between the nano-nickel powder and the contact area between the nano-nickel powder and the substrate to form a metallurgical bond, while preserving the internal nanostructure of the nano-nickel powder, resulting in a single-layer nano-nickel component. By using electroplated electrodes of similar shape for resistance heating additive manufacturing of nano-nickel powder plates, larger-sized components can be printed in a single step, and the final component has good density.

[0032] In a preferred embodiment of the present invention, in step S1, the particle size of the nano-nickel powder is 10-50 nm. Nano-powder generally refers to powder with a particle size within 100 nm. Selecting a particle size range of 10-50 nm ensures relatively uniform particle size, results in nanocrystalline structures prepared from this particle size exhibiting excellent comprehensive mechanical properties, and controls the particle size within this range to better balance economic cost and quality. Further, nano-nickel powder can be obtained by ball milling micron-sized nickel powder using a planetary ball mill. The specific preparation method includes: ball milling the micron-sized nickel powder with a ball-to-powder ratio of 15-20:1, a ball milling speed of 500-800 rpm, and a ball milling time of 6-15 hours. The nano-nickel powder is obtained after ball milling. Optionally, the particle size distribution of the micron-sized nickel powder is 45-106 μm.

[0033] In an optional embodiment of the present invention, the nano-nickel powder may be selected from nano-pure nickel powder or nano-nickel-based powder.

[0034] In a second aspect, the present invention provides a large-size nickel nanoparticle component, which is fabricated using the aforementioned resistive thermal additive manufacturing method for large-size nickel nanoparticle components.

[0035] Based on the reasons mentioned above, the large-size nickel nanoparticles of the present invention have nanoscale dimensions (20~80nm), metallurgical bonding between nanocrystals, tensile strength of GPa level (1~30GPa), and component size of centimeters / decimeter level, which significantly improves the component size and overall performance compared with the prior art.

[0036] A third aspect of the present invention provides a resistance thermal additive manufacturing apparatus for large-size nano-nickel components, the structure of which is referenced. Figure 3The apparatus is used to realize the aforementioned method for preparing large-size nano-nickel components using electrostatic powder laying and rolling resistance thermal additive manufacturing processes. The resistance thermal additive manufacturing apparatus includes an electrostatic powder laying unit, a powder compaction unit, and an energized pressurization unit. The electrostatic powder spreading unit includes an insulating support, and a powder feeding funnel, a powder feeding roller, an insulator, and a non-contact powder spreading electrode disposed on the insulating support. The insulator is located in front of the non-contact powder spreading electrode and is bonded to the non-contact powder spreading electrode. The powder compaction unit includes a multi-stage roller disposed on the insulating support, and the multi-stage roller is located behind the non-contact powder spreading electrode; The energized pressurizing unit includes an energized electrode configured as a roller-type pressurizing structure, which is located behind the multi-stage rollers.

[0037] This invention addresses the challenge of achieving integrated, continuous, and efficient operation in the powder feeding, spreading, and forming processes of arc thermal additive manufacturing devices for large-size, low-cost nano-nickel components. The device integrates an energized electrode with a roller-type pressure structure behind a non-contact electrostatic powder spreading device (including an electrostatic powder spreading unit and a powder compaction unit). The device uses a powder feeding funnel to hold nano-nickel powder, which is then roughly and quantitatively spread onto a substrate via a powder feeding roller. A gap exists between the insulating support and the powder feeding funnel to ensure the rotation of the roller. A non-contact powder spreading electrode is positioned behind the insulated powder feeding roller. This electrode uses electrostatic force, oscillation, and compaction to level and compact the powder. Furthermore, a multi-stage roller (with an insulated outer surface) is integrated into the insulating support of the non-contact electrostatic powder spreading device and placed behind the powder spreading electrode to further compact the nano-nickel powder, resulting in a nano-nickel powder layer and ensuring higher density in subsequent formed components. Finally, the nano-nickel powder layer is subjected to resistance thermal additive manufacturing through the energized electrode of the roller-type pressure structure. Compared with other types of energized electrodes, the energized electrode of the roller-type pressure structure can be used in conjunction with the electrostatic powder spreading unit and the powder compaction unit to carry out integrated operation of powder feeding, powder spreading, compaction and energized pressure forming. Secondly, it can adapt to structures such as planar and cylindrical curved surfaces, and can operate efficiently on the above structures.

[0038] In summary, the large-size nickel nanoparticle resistive thermal additive manufacturing device provided by this invention can realize online powder feeding, powder spreading, powder leveling, multi-stage compaction, and continuous additive manufacturing. After proposing the nickel nanoparticle resistive thermal additive manufacturing process, it successfully solved the problem that the nickel nanoparticle resistive thermal additive manufacturing process cannot be flexibly and continuously integrated, and realized the low-cost, high-efficiency and flexible preparation of large-size nickel nanoparticle components.

[0039] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0040] Example 1 A method for resistive thermal additive manufacturing of large-size nickel nanoparticles is disclosed. This embodiment employs a combination of electrostatic powder laying and rolling resistive thermal additive manufacturing processes to prepare large-size nickel nanoparticles, and is implemented according to the following steps: Step S1, Preparation of nano-nickel powder: Nano-nickel powder with a particle size distribution of 10-50 nm is prepared from micron-sized nickel powder using a planetary ball mill, including: Step 1.1: Select In625 nickel-based alloy powder as the initial material. The powder type is GH3625 and the powder particle size is 45~106μm. Put the GH3625 powder into the grinding jar of the planetary ball mill at a ball-to-powder ratio of 20:1 to prepare for grinding. Step 1.2: Set the speed of the planetary ball mill to 700 rpm and the grinding time to 12 hours. Pause the cooling every 30 minutes to avoid high-temperature oxidation. Step 1.3: After 12 hours of grinding, GH3625 powder with a particle size of 45~106μm is prepared into nano-GH3625 powder with a structure of 10~50 nm. A small amount of powder is taken out and placed under TEM for characterization to ensure that the microstructure of the prepared powder is 10~50 nm.

[0041] Step S2 involves fabricating large-size nickel nano-components using a combination of electrostatic powder laying and resistance thermal additive manufacturing processes. The process utilizes the aforementioned additive manufacturing apparatus (the apparatus structure is described in detail below). Figure 3 )accomplish: Step 2.1: Quantitatively deliver nano-nickel powder through a powder feeding funnel, distribute it onto the surface of the substrate (30CrMo steel) via a powder feeding roller, then use a non-contact powder spreading electrode to vibrate, level and initially compact the nano-nickel powder, and finally use a multi-stage roller to further compact it to obtain a nano-nickel powder layer. Step 2.2: Apply an electric electrode with a roller-type pressure structure to the upper surface of the nano-nickel powder layer for energization and pressure. The substrate on the lower surface serves as the electric electrode to energize the nano-nickel powder layer, forming a current loop with the electric electrode on the upper surface. The resistive heating effect generated in the current loop selectively melts the gaps between the nano-nickel powder and the contact area between the nano-nickel powder and the substrate to form a metallurgical bond, while retaining the nanostructure inside the nano-nickel powder, to obtain a single-layer nano-nickel component. The parameters for energization and pressure are: voltage of 7.0V, current of 5000A, load of 20MPa, single rolling width of 10mm, and rolling speed of 3mm / s. Step 2.3: Using the above-mentioned single-layer nano-nickel component as a new substrate, a nano-nickel powder layer is laid on the single-layer nano-nickel component in the manner of step 2.1. Then, resistance thermal additive manufacturing is performed on the laid nano-nickel powder layer in step 2.2. Steps 2.1 and 2.2 are repeated 4 times to perform multi-layer resistance thermal additive manufacturing, and metallurgical bonding is formed between the layers to obtain a 1000mm×20mm×8mm nanocrystalline nickel component (5 layers).

[0042] Example 2 A method for resistive thermal additive manufacturing of large-size nickel nanoparticles is disclosed. This embodiment employs a combination of powder pressing and flat-plate resistive thermal additive manufacturing processes to prepare large-size nickel nanoparticles, and is implemented according to the following steps: Step S1, Preparation of nano-nickel powder: Nano-nickel powder with a particle size distribution of 10-50 nm is prepared from micron-sized nickel powder using a planetary ball mill, including: Step 1.1: Select In625 nickel-based alloy powder as the initial material. The powder type is GH3625 and the powder particle size is 45~106μm. Put the GH3625 powder into the grinding jar of the planetary ball mill at a ball-to-powder ratio of 20:1 to prepare for grinding. Step 1.2: Set the speed of the planetary ball mill to 700 rpm and the grinding time to 12 hours. Pause the cooling every 30 minutes to avoid high-temperature oxidation. Step 1.3: After 12 hours of grinding, GH3625 powder with a particle size of 45~106μm is prepared into nano-GH3625 powder with a structure of 10~50 nm. A small amount of powder is taken out and placed under TEM for characterization to ensure that the microstructure of the prepared powder is 10~50 nm.

[0043] Step S2 involves fabricating large-size nickel nanostructures using a combination of powder pressing and flat-plate resistance thermal additive manufacturing processes, the process of which is described in detail below. Figure 4 : Step 2.1: Use a powder pressing mold to press the above GH3625 nano powder into a dense nano nickel powder plate of 180mm×210mm×2mm at 500MPa, and then place the pressed nano nickel powder plate on a substrate (30CrMo steel). Step 2.2: Place the GH3625 nano nickel powder plate with dimensions of 180mm×210mm×2mm on the substrate between flat graphite electrodes with dimensions of 180mm×210mm×2mm and perform an energizing operation. The energizing parameters are current 4000A, voltage 6.5V, and load 1MPa. Utilize the resistive heating effect generated in the current loop formed by the graphite electrodes on the lower and upper surfaces to selectively melt the gaps between the nano nickel powder and the contact area between the nano nickel powder and the substrate to form a metallurgical bond, while retaining the nanostructure inside the nano nickel powder, to obtain a single-layer nano nickel component. Step 2.3: Using the above-mentioned single-layer nickel nanomaterial as a new substrate, the pre-pressed nickel nanomaterial powder plate is placed on the single-layer nickel nanomaterial using the method in Step 2.1. Then, the nickel nanomaterial powder plate placed on the single-layer nickel nanomaterial is subjected to resistance thermal additive manufacturing using Step 2.2. Steps 2.1 and 2.2 are repeated 3 times to perform multi-layer resistance thermal additive manufacturing, achieving metallurgical bonding between layers to obtain a large-size nickel nanomaterial (180mm×210mm×6mm, 4 layers).

[0044] Example 3 A method for resistive thermal additive manufacturing of large-size nano-nickel components differs from Example 1 only in the parameters of the applied voltage and pressure. Specifically, the voltage parameter is 5V, the current parameter is 2000A, the load is 1MPa, the single rolling width is 1mm, and the rolling speed is 2mm / s.

[0045] Example 4 A method for resistive thermal additive manufacturing of large-size nano-nickel components differs from Example 1 only in the parameters of the applied voltage and pressure. Specifically, the voltage parameter is 10V, the current parameter is 7000A, the load is 100MPa, the single rolling width is 20mm, and the rolling speed is 6mm / s.

[0046] Example 5 A method for resistive thermal additive manufacturing of large-size nano-nickel components differs from Example 2 only in the power-on operating parameters: the voltage parameter is 2V and the current parameter is 2000A.

[0047] Example 6 A method for resistive thermal additive manufacturing of large-size nano-nickel components differs from Example 2 only in the power-on operating parameters: the voltage parameter is 10V and the current parameter is 7000A.

[0048] Comparative Example 1 Taking traditional laser coaxial powder feeding additive manufacturing as an example, the fabrication process of micron-sized nickel metal components includes the following steps: Step 1: Select 30CrMo steel as the substrate and In625 nickel-based alloy powder as the initial material. The powder type is GH3625 and the powder particle size is 45~106μm. Step 2: Perform laser coaxial powder feeding additive printing. The laser power is 8000W, the travel speed is 20mm / s, the track spacing is 1.2mm, the powder feeding speed is 1.8g / min, the preset layer height is 1.5mm, the protective gas flow rate is 0.8L / min, the powder feeding method is coaxial ring, the protective gas is 100% argon, the additive layer overlap rate per pass is 45%, and the blank diameter is 4mm.

[0049] Step 3: Repeat step 2 to perform 30 layers and 120 passes of additive printing to produce a nickel-based alloy additive component with a height of 60mm, a length of 100mm, and a width of 150mm.

[0050] Performance testing: The tensile strength of the nickel components in the above embodiments and comparative examples was tested using the indentation method, following the standard GB / T 39635-2020. Elongation (plasticity) was also tested using the micropillar compression method (micropillars, typically 200 nm in diameter and 800 nm in height, were prepared from bulk material using focused ion beam (FIB). The micropillars were placed under a compression device, and an axial load was slowly applied. The load-displacement curves were recorded, and the elongation was calculated from the strength changes on the load-displacement curves). The test results are shown in Table 1.

[0051] Table 1

[0052] As can be seen from Table 1 above, the metallic nickel components prepared in this application exhibit significantly improved mechanical properties compared to metallic nickel components prepared by laser coaxial powder feeding additive manufacturing in the prior art. The tensile strength increases by approximately 10 times, and the elongation also shows a significant improvement, increasing by approximately 1.2 to 1.5 times. This invention fundamentally solves the problem of traditional laser / arc melting additive manufacturing technology damaging the nanostructure, leading to a significant reduction in the performance of the prepared components. Furthermore, this invention can achieve component sizes at the centimeter / decimeter level, representing a significant improvement in both component size and overall performance compared to the prior art.

[0053] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. The present invention can also be implemented in other specific ways or forms without departing from its spirit or essential characteristics. Therefore, the described embodiments should be considered illustrative rather than limiting in any respect. The scope of the present invention should be defined by the appended claims, and any variations equivalent to the intent and scope of the claims should also be included within the scope of the present invention.

Claims

1. A method for resistive thermal additive manufacturing of large-size nano-nickel components, characterized in that, Includes the following steps: Step S1, providing nano-nickel powder; Step S2: The nano-nickel powder is deposited on the substrate surface to form a nano-nickel powder layer or the nano-nickel powder is pressed into a nano-nickel powder plate and placed on the substrate surface. Step S3: The nano-nickel powder layer or the nano-nickel powder plate is subjected to resistance heating additive manufacturing. The resistance heating effect is used to selectively melt the gaps between the nano-nickel powder and the contact area between the nano-nickel powder and the substrate to form a metallurgical bond, while retaining the nanostructure inside the nano-nickel powder, to obtain a single-layer nano-nickel component. Step S4: Using the single-layer nickel nanostructure as a new substrate, repeat steps S2 and S3 to perform multilayer resistance thermal additive manufacturing until the desired large-size nickel nanostructure is obtained.

2. The resistance thermal additive manufacturing method according to claim 1, characterized in that, In step S2, the nano-nickel powder layer is laid using an electrostatic powder laying process, which specifically includes the following steps: nano-nickel powder is quantitatively conveyed through a powder feeding funnel, distributed to the substrate surface by a powder feeding roller, and then the nano-nickel powder is vibrated, leveled and initially compacted using a non-contact powder laying electrode. Finally, multi-stage rollers are used for further compaction to obtain the nano-nickel powder layer.

3. The resistance thermoforming additive manufacturing method according to claim 1, characterized in that, In step S2, the nano-nickel powder is pressed into a nano-nickel powder plate under a pressure of 0.1~3 GPa.

4. The resistance thermoforming additive manufacturing method according to claim 1, characterized in that, In step S3, the nano-nickel powder layer is subjected to resistance thermal additive manufacturing, specifically including: An electric electrode with a roller-type pressure structure is applied to the upper surface of the nano-nickel powder layer to apply current and pressure. The substrate on the lower surface serves as the other electric electrode, forming a current loop with the electric electrode on the upper surface. The resistance heating effect generated in the current loop is used to selectively melt the gaps between the nano-nickel powder and the contact area between the nano-nickel powder and the substrate to form a metallurgical bond, while retaining the nanostructure inside the nano-nickel powder, thus obtaining a single-layer nano-nickel component.

5. The resistance thermoforming additive manufacturing method according to claim 4, characterized in that, The parameters for applying power and pressure include: voltage of 5~10V, current of 2000~7000A, load of 1~100MPa, single rolling width of 1~20mm, and rolling speed of 2~6mm / s.

6. The resistance thermoforming additive manufacturing method according to claim 1, characterized in that, In step S3, the nano-nickel powder plate undergoes resistance thermal additive manufacturing, specifically including: A planar electrode is applied to the upper and lower surfaces of a nano-nickel powder plate to conduct an electric current operation. The electrode on the lower surface and the electrode on the upper surface form a current loop. The resistive heating effect generated in the current loop selectively melts the gaps between the nano-nickel powder and the contact area between the nano-nickel powder and the substrate to form a metallurgical bond, while retaining the nanostructure inside the nano-nickel powder, thus obtaining a single-layer nano-nickel component.

7. The resistance thermoforming additive manufacturing method according to claim 6, characterized in that, The voltage parameters for the power-on operation are 2~10V, the current parameters are 2000~7000A, and the load is 0~100MPa.

8. The resistance thermoforming additive manufacturing method according to claim 1, characterized in that, In step S1, the particle size of the nano-nickel powder is 10~50nm.

9. The resistance thermal additive manufacturing method according to claim 1 or 8, characterized in that, In step S1, the nano-nickel powder is prepared by the following steps: micron-sized nickel powder is ball-milled with a ball-to-material ratio of 15-20:1, a ball milling speed of 500-800 rpm, and a ball milling time of 6-15 h. The nano-nickel powder is obtained after the ball milling is completed.

10. An apparatus for resistive thermal additive manufacturing of large-size nano-nickel components, used to implement the resistive thermal additive manufacturing method of claim 1, characterized in that, The additive manufacturing apparatus includes an electrostatic powder spreading unit, a powder compaction unit, and an energized pressurization unit; The electrostatic powder spreading unit includes an insulating support, and a powder feeding funnel, a powder feeding roller, an insulator, and a non-contact powder spreading electrode disposed on the insulating support. The insulator is located in front of the non-contact powder spreading electrode and is bonded to the non-contact powder spreading electrode. The powder compaction unit includes a multi-stage roller disposed on the insulating support, and the multi-stage roller is located behind the non-contact powder spreading electrode; The energized pressurizing unit includes an energized electrode configured as a roller-type pressurizing structure, which is located behind the multi-stage rollers.

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